Convection: Transmission of energy or mass by a medium involving movement of the medium itself. The circulatory movement that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed; Webster, 10th ed)Thermal Conductivity: The heat flow across a surface per unit area per unit time, divided by the negative of the rate of change of temperature with distance in a direction perpendicular to the surface. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Air Movements: The motion of air currents.Diffusion: The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space. Diffusion, especially FACILITATED DIFFUSION, is a major mechanism of BIOLOGICAL TRANSPORT.Coriolis Force: The apparent deflection (Coriolis acceleration) of a body in motion with respect to the earth, as seen by an observer on the earth, attributed to a fictitious force (Coriolis force) but actually caused by the rotation of the earth. In a medical context it refers to the physiological effects (nausea, vertigo, dizziness, etc.) felt by a person moving radially in a rotating system, as a rotating space station. (From Random House Unabridged Dictionary, 2d ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Hydrodynamics: The motion of fluids, especially noncompressible liquids, under the influence of internal and external forces.Hemodiafiltration: The combination of hemodialysis and hemofiltration either simultaneously or sequentially. Convective transport (hemofiltration) may be better for removal of larger molecular weight substances and diffusive transport (hemodialysis) for smaller molecular weight solutes.Atmosphere: The gaseous envelope surrounding a planet or similar body. (From Random House Unabridged Dictionary, 2d ed)Rheology: The study of the deformation and flow of matter, usually liquids or fluids, and of the plastic flow of solids. The concept covers consistency, dilatancy, liquefaction, resistance to flow, shearing, thixotrophy, and VISCOSITY.Respiratory Transport: The processes of diffusion across the BLOOD-AIR BARRIER, and the chemical reactions coupled with diffusion that effect the rate of PULMONARY GAS EXCHANGE, generally at the alveolar level.Cetylpyridinium: Cationic bactericidal surfactant used as a topical antiseptic for skin, wounds, mucous membranes, instruments, etc.; and also as a component in mouthwash and lozenges.Models, Theoretical: Theoretical representations that simulate the behavior or activity of systems, processes, or phenomena. They include the use of mathematical equations, computers, and other electronic equipment.Extracellular Fluid: The fluid of the body that is outside of CELLS. It is the external environment for the cells.Heating: The application of heat to raise the temperature of the environment, ambient or local, or the systems for accomplishing this effect. It is distinguished from HEAT, the physical property and principle of physics.Influenzavirus A: A genus in the family ORTHOMYXOVIRIDAE causing influenza and other diseases in humans and animals. It contains many strains as well as antigenic subtypes of the integral membrane proteins hemagglutinin (HEMAGGLUTININS) and NEURAMINIDASE. The type species is INFLUENZA A VIRUS.Boron Neutron Capture Therapy: A technique for the treatment of neoplasms, especially gliomas and melanomas in which boron-10, an isotope, is introduced into the target cells followed by irradiation with thermal neutrons.Models, Biological: Theoretical representations that simulate the behavior or activity of biological processes or diseases. For disease models in living animals, DISEASE MODELS, ANIMAL is available. Biological models include the use of mathematical equations, computers, and other electronic equipment.Hemofiltration: Extracorporeal ULTRAFILTRATION technique without HEMODIALYSIS for treatment of fluid overload and electrolyte disturbances affecting renal, cardiac, or pulmonary function.Pressure: A type of stress exerted uniformly in all directions. Its measure is the force exerted per unit area. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Air: The mixture of gases present in the earth's atmosphere consisting of oxygen, nitrogen, carbon dioxide, and small amounts of other gases.Hydrostatic Pressure: The pressure due to the weight of fluid.Biological Transport: The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.Body Temperature Regulation: The processes of heating and cooling that an organism uses to control its temperature.Microfluidic Analytical Techniques: Methods utilizing the principles of MICROFLUIDICS for sample handling, reagent mixing, and separation and detection of specific components in fluids.Hot Temperature: Presence of warmth or heat or a temperature notably higher than an accustomed norm.Water: A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Temperature: The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.Physics: The study of those aspects of energy and matter in terms of elementary principles and laws. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Hepatitis, Infectious Canine: A contagious disease caused by canine adenovirus (ADENOVIRUSES, CANINE) infecting the LIVER, the EYE, the KIDNEY, and other organs in dogs, other canids, and bears. Symptoms include FEVER; EDEMA; VOMITING; and DIARRHEA.Dog Diseases: Diseases of the domestic dog (Canis familiaris). This term does not include diseases of wild dogs, WOLVES; FOXES; and other Canidae for which the heading CARNIVORA is used.Solar Activity: Any type of variation in the appearance of energy output of the sun. (NASA Thesaurus, 1994)United States National Aeronautics and Space Administration: An independent Federal agency established in 1958. It conducts research for the solution of problems of flight within and outside the Earth's atmosphere and develops, constructs, tests, and operates aeronautical and space vehicles. (From U.S. Government Manual, 1993)Communication: The exchange or transmission of ideas, attitudes, or beliefs between individuals or groups.Space Flight: Travel beyond the earth's atmosphere.Astronauts: Members of spacecraft crew including those who travel in space, and those in training for space flight. (From Webster, 10th ed; Jane's Aerospace Dictionary, 3d ed)Cosmic Radiation: High-energy radiation or particles from extraterrestrial space that strike the earth, its atmosphere, or spacecraft and may create secondary radiation as a result of collisions with the atmosphere or spacecraft.North CarolinaSouth CarolinaAir Microbiology: The presence of bacteria, viruses, and fungi in the air. This term is not restricted to pathogenic organisms.Pacific Islands: The islands of the Pacific Ocean divided into MICRONESIA; MELANESIA; and POLYNESIA (including NEW ZEALAND). The collective name Oceania includes the aforenamed islands, adding AUSTRALIA; NEW ZEALAND; and the Malay Archipelago (INDONESIA). (Webster's New Geographical Dictionary, 1988, p910, 880)Bayes Theorem: A theorem in probability theory named for Thomas Bayes (1702-1761). In epidemiology, it is used to obtain the probability of disease in a group of people with some characteristic on the basis of the overall rate of that disease and of the likelihood of that characteristic in healthy and diseased individuals. The most familiar application is in clinical decision analysis where it is used for estimating the probability of a particular diagnosis given the appearance of some symptoms or test result.Biomechanical Phenomena: The properties, processes, and behavior of biological systems under the action of mechanical forces.Phylogeny: The relationships of groups of organisms as reflected by their genetic makeup.Mathematical Concepts: Numeric or quantitative entities, descriptions, properties, relationships, operations, and events.Motion: Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.Motion Perception: The real or apparent movement of objects through the visual field.Mathematics: The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)Finite Element Analysis: A computer based method of simulating or analyzing the behavior of structures or components.Computer Simulation: Computer-based representation of physical systems and phenomena such as chemical processes.Stress, Mechanical: A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.Models, Anatomic: Three-dimensional representation to show anatomic structures. Models may be used in place of intact animals or organisms for teaching, practice, and study.Bite Force: The force applied by the masticatory muscles in dental occlusion.

Acinar flow irreversibility caused by perturbations in reversible alveolar wall motion. (1/141)

Mixing associated with "stretch-and-fold" convective flow patterns has recently been demonstrated to play a potentially important role in aerosol transport and deposition deep in the lung (J. P. Butler and A. Tsuda. J. Appl. Physiol. 83: 800-809, 1997), but the origin of this potent mechanism is not well characterized. In this study we hypothesized that even a small degree of asynchrony in otherwise reversible alveolar wall motion is sufficient to cause flow irreversibility and stretch-and-fold convective mixing. We tested this hypothesis using a large-scale acinar model consisting of a T-shaped junction of three short, straight, square ducts. The model was filled with silicone oil, and alveolar wall motion was simulated by pistons in two of the ducts. The pistons were driven to generate a low-Reynolds-number cyclic flow with a small amount of asynchrony in boundary motion adjusted to match the degree of geometric (as distinguished from pressure-volume) hysteresis found in rabbit lungs (H. Miki, J. P. Butler, R. A. Rogers, and J. Lehr. J. Appl. Physiol. 75: 1630-1636, 1993). Tracer dye was introduced into the system, and its motion was monitored. The results showed that even a slight asynchrony in boundary motion leads to flow irreversibility with complicated swirling tracer patterns. Importantly, the kinematic irreversibility resulted in stretching of the tracer with narrowing of the separation between adjacent tracer lines, and when the cycle-by-cycle narrowing of lateral distance reached the slowly growing diffusion distance of the tracer, mixing abruptly took place. This coupling of evolving convective flow patterns with diffusion is the essence of the stretch-and-fold mechanism. We conclude that even a small degree of boundary asynchrony can give rise to stretch-and-fold convective mixing, thereby leading to transport and deposition of fine and ultrafine aerosol particles deep in the lung.  (+info)

Cytoplasmic transport of fatty acids in rat enterocytes: role of binding to fatty acid-binding protein. (2/141)

The intracellular movement of fatty acids is thought to be facilitated through codiffusion with fatty acid-binding protein (FABP). This facilitation may occur by decreasing binding to immobile membranes, leading to faster cytoplasmic diffusion. The aims of this study were to measure the intracellular transport of 12-N-methyl-(7-nitrobenzo-2-oxa-1,3-diazol)aminostearate (NBD-stearate) in villus rat enterocytes and to determine 1) the mechanism of its cytoplasmic transport and 2) if its transport rate correlated with the known variation of FABP binding capacity along the length of the small intestine. Two-dimensional laser photobleaching was used to measure the movement of a fluorescent fatty acid NBD-stearate in enterocytes isolated from different segments of rat intestine. The fraction of NBD-stearate found in the cytostol of enterocytes was determined by differential centrifugation. Cytoplasmic transport of NBD-stearate occurred solely by diffusion and not by convection. Diffusion was homogeneous (nondirectional), consistent with isotropic diffusion. The diffusion rate varied with location along the intestine, correlating with the local FABP concentration and measured cytosolic binding. We conclude that cytoplasmic proteins like FABP promote the intracellular transport of fatty acids by enhancing their diffusive flux. We suggest that facilitation is not specific for a particular cell type but occurs in a variety of cells that transport fatty acids and may contain different types of FABP.  (+info)

Clothing convective heat exchange--proposal for improved prediction in standards and models. (3/141)

Convection is an important determinant for both sensible and evaporative heat exchange. Heat transfer by convection for normal boundary conditions is readily described by simple power functions. Clothing affects convection in various ways and existing characterisation of clothing by its static insulation values produces inaccurate prediction of sensible heat exchange, eventually leading to erroneous risk assessment. The present paper reviews various methods for evaluation of clothing convective (sensible) heat exchange. Based on available data, two equations are proposed for determination of the reduction of the total insulation values obtained under static, still wind conditions as a consequence of wind and walking effects. The equations apply from 0 to 1.84 clo, from 0.2 to 3 m/s and for walking speeds up to 1.2 m/s. The equations are incorporated in ISO 7933 to provide a more realistic and accurate prediction of sensible heat transfer through clothing.  (+info)

The effects of wind and human movement on the heat and vapour transfer properties of clothing. (4/141)

This paper integrates the research presented in the papers in this special issue of Holmer et al. and Havenith et al. [Holmer, I., Nilsson, H., Havenith, G., Parsons, K. C. (1999) Clothing convective heat exchange: proposal for improved prediction in standards and models. Annals of Occupational Hygiene, in press; Havenith, G., Holmer, I., den Hartog, E. and Parsons, K. C. (1999) Clothing evaporative heat resistance: proposal for improved representation in standards and models. Annals of Occupational Hygiene, in press] to provide a practical suggestion for improving existing clothing models so that they can account for the effects of wind and human movement. The proposed method is presented and described in the form of a BASIC computer program. Analytical methods (for example ISO 7933) for the assessment of the thermal strain caused by human exposure to hot environments require a mathematical quantification of the thermal properties of clothing. These effects are usually considered in terms of 'dry' thermal insulation and vapour resistance. This simple 'model' of clothing can account for the insulation properties of clothing which reduce heat loss (or gain) between the body and the environment and, for example, the resistance to the transfer of evaporated sweat from the skin, which is important for cooling the body in a hot environment. When a clothed person is exposed to wind, however, and when the person is active, there is a potentially significant limitation in the simple model of clothing presented above. Heat and mass transfer can take place between the microclimate (within clothing and next to the skin surface) and the external environment. The method described in this paper 'corrects' static values of clothing properties to provide dynamic values that take account of wind and human movement. It therefore allows a more complete representation of the effects of clothing on the heat strain of workers.  (+info)

Efficacy of two methods for reducing postbypass afterdrop. (5/141)

BACKGROUND: Afterdrop, defined as the precipitous reduction in core temperature after cardiopulmonary bypass, results from redistribution of body heat to inadequately warmed peripheral tissues. The authors tested two methods of ameliorating afterdrop: (1) forced-air warming of peripheral tissues and (2) nitroprusside-induced vasodilation. METHODS: Patients were cooled during cardiopulmonary bypass to approximately 32 degrees C and subsequently rewarmed to a nasopharyngeal temperature near 37 degrees C and a rectal temperature near 36 degrees C. Patients in the forced-air protocol (n = 20) were assigned randomly to forced-air warming or passive insulation on the legs. Active heating started with rewarming while undergoing bypass and was continued for the remainder of surgery. Patients in the nitroprusside protocol (n = 30) were assigned randomly to either a control group or sodium nitroprusside administration. Pump flow during rewarming was maintained at 2.5 l x m(-2) x min(-1) in the control patients and at 3.0 l x m(-2) x min(-1) in those assigned to sodium nitroprusside. Sodium nitroprusside was titrated to maintain a mean arterial pressure near 60 mm Hg. In all cases, a nasopharyngeal probe evaluated core (trunk and head) temperature and heat content. Peripheral compartment (arm and leg) temperature and heat content were estimated using fourth-order regressions and integration over volume from 18 intramuscular needle thermocouples, nine skin temperatures, and "deep" hand and foot temperature. RESULTS: In patients warmed with forced air, peripheral tissue temperature was higher at the end of warming and remained higher until the end of surgery. The core temperature afterdrop was reduced from 1.2+/-0.2 degrees C to 0.5+/-0.2 degrees C by forced-air warming. The duration of afterdrop also was reduced, from 50+/-11 to 27+/-14 min. In the nitroprusside group, a rectal temperature of 36 degrees C was reached after 30+/-7 min of rewarming. This was only slightly faster than the 40+/-13 min necessary in the control group. The afterdrop was 0.8+/-0.3 degrees C with nitroprusside and lasted 34+/-10 min which was similar to the 1.1+/-0.3 degrees C afterdrop that lasted 44+/-13 min in the control group. CONCLUSIONS: Cutaneous warming reduced the core temperature afterdrop by 60%. However, heat-balance data indicate that this reduction resulted primarily because forced-air heating prevented the typical decrease in body heat content after discontinuation of bypass, rather than by reducing redistribution. Nitroprusside administration slightly increased peripheral tissue temperature and heat content at the end of rewarming. However, the core-to-peripheral temperature gradient was low in both groups. Consequently, there was little redistribution in either case.  (+info)

Influence of convection on small molecule clearances in online hemodiafiltration. (6/141)

BACKGROUND: Dialysis efficacy is mostly influenced by dialyzer clearance. Urea clearance may be estimated in vitro by total ion clearance, which can be obtained by conductivity measurements. We have previously used this approach to assess in vitro clearances in a system mimicking predilutional and postdilutional online hemodiafiltration with a wide range of QD, QB, and ultrafiltration rates. Our current study elaborates on a formula that allows the prediction of the influence of ultrafiltration on small molecule clearances, and validates the mathematical approach both experimentally in vitro and clinically in vivo data. METHODS: Two conductivimeters in the dialysate side of an E-2008 Fresenius machine were used. HF80 and HF40 polysulfone dialyzers were used; reverse osmosis water and dialysate were used for blood and dialysate compartments, respectively. Study conditions included QB of 300 and 400 mL/min and QD of 500 and 590 mL/min, with a range of ultrafiltration rate from 0 to 400 mL/min in postdilutional hemodiafiltration and to 590 mL/min in predilutional hemodiafiltration. Urea clearances were determined in the in vivo studies, which included 0, 50, 100, and 150 mL/min ultrafiltration rates. RESULTS: The ultrafiltration rate and clearance were significantly correlated (R > 0.9, P < 0.001) and fitted a linear model (P < 0.001) in all of the experimental conditions. The following formula fitted the experimental points with an error <2% for both postdilutional and predilutional online diafiltration in vitro, respectively. K = K0 + [(QB - K0)/(QB)] x ultrafiltration rateK = K0 + [((QD x QB)/(QB + QD) - K0)/QD] x ultrafiltration rate where K is the clearance; K0 is the clearance with nil ultrafiltration rate; QD is the total dialysate produced (in commercial HDF, QD = QDi + Qinf). Since weight loss was maintained at 0, ultrafiltration rate = infusion flow. QB is the "blood" line flow. The formula was also verified in vivo in clinical postdilutional hemodiafiltration with a QB taking into account the cellular and water compartments. DISCUSSION: In vitro, by simply determining the clearance in conventional dialysis, the total clearance for any ultrafiltration rate may be estimated in both predilutional and postdilutional online diafiltration with an error of less than 2%. The same applies to in vivo postdilutional hemodiafiltration when the formula takes into account the cellular and water composition of blood.  (+info)

Contaminant dispersion in the vicinity of a worker in a uniform velocity field. (7/141)

The transportation of gaseous contaminant from a low and moderate low impulse (momentum<1 m s(-1)) source to the breathing zone was studied in a uniform air stream flow. Results of the effects of the direction and the velocity of principal air flow, convection due to a human body, arm movement of a human being and the type of source on the concentration profiles are presented. Three important results were obtained. Firstly, for a given low and moderate impulse low impulse contaminant source in the near field of a worker, his/her orientation relative to the principal air flow direction is the most important factor in reducing occupational exposure, with an air velocity of about 0.3 m s(-1). Secondly, the effect of convection resulting from body heat on air flow was lower than expected. Thirdly, arm movements influence contaminant dispersion, and should be included when models assessing exposure are developed. The present data can also be used to validate existing computational fluid dynamic (CFD) models.  (+info)

Monitoring response to convection-enhanced taxol delivery in brain tumor patients using diffusion-weighted magnetic resonance imaging. (8/141)

Convection-enhanced drug delivery (CEDD) is a novel approach to enhance the delivery of drugs directly into brain tumors. We have used diffusion-weighted MRI (DWMRI) to monitor the effects of intratumoral CEDD in three brain tumor patients treated with Taxol. Clear changes in the images and the water diffusion parameters were observed shortly after the initiation of treatment. Initially, a bright area corresponding to decreased diffusion appeared, followed by the appearance of a dark area of increased diffusion within the bright area. The time to appearance of the dark area varied among the patients, suggesting different response rates. In this work, we have demonstrated the feasibility of using DWMRI as a noninvasive tool to achieve unique early tissue characterization not attainable by other conventional imaging methods.  (+info)

The evaporation rate and internal convective flows of a sessile droplet with a pinned contact line were formulated and investigated numerically. We developed and analyzed a unified numerical model that includes the effects of temperature, droplet volume, and contact angle on evaporation rate and internal flows. The temperature gradient on the air/liquid interface causes an internal flow due to Marangoni stress, which provides good convective mixing within the droplet, depending upon Marangoni number. As the droplet volume decreases, the thermal gradient becomes smaller and the Marangoni flow becomes negligible. Simultaneously, as the droplet height decreases, evaporation-induced flow creates a large jet-like flow radially toward the contact line. For a droplet containing suspended particles, this jet-like convective flow carries particles toward the contact line and deposits them on the surface, forming the so-called "coffee ring stain". In addition, we reported a simple polynomial correlation ...
Convection-enhanced delivery permits the direct homogeneous delivery of small- and large-molecular-weight putative therapeutics to the nervous system in a manner that bypasses the blood-nervous system barrier. The development of co-infused surrogate imaging tracers (for computed tomography and MRI) allows for the real-time, noninvasive monitoring of infusate distribution during convective delivery. Real-time image monitoring of convective distribution of therapeutic agents insures that targeted structures/nervous system regions are adequately perfused, enhances safety, informs efficacy (or lack thereof) of putative agents, and provides critical information regarding the properties of convection-enhanced delivery in normal and various pathologic tissue states ...
Define Convection, Rotation and Planetary Transits. Convection, Rotation and Planetary Transits synonyms, Convection, Rotation and Planetary Transits pronunciation, Convection, Rotation and Planetary Transits translation, English dictionary definition of Convection, Rotation and Planetary Transits. Jean Baptiste Camille 1796-1875. French artist of the Barbizon school whose landscape paintings influenced the impressionists. n Jean Baptiste Camille ....
Liquid lead bismuth eutectic (LBE) is very corrosive to steels. To mitigate structural corrosion of LBE systems, active oxygen control technique is developed. To enhance the speed of oxygen transport in liquid LBE, natural convection has been proposed. This paper numerically analyzes the oxygen transport in a natural convection induced LBE enclosure. Different temperature boundary conditions are added to the container. Both laminar and turbulent LBE flows which are distinguished by strength of flow measured are analyzed. Three laminar cases: (a) heated from the bottom and cooled from the top of the container; (b) heated from the sidewalls and cooled from the top of the container; (c) one sidewall heated and the opposite wall cooled, and one fully turbulent case with one sidewall heated and the opposite sidewall cooled are chosen. Oxidization in near wall areas and formation of oxide layers on container surfaces are considered. In each case, the characteristic velocity and oxygen diffusion time are
Article Entropy generation for unsteady natural convection and thermal radiation inside a porous enclosure. Entropy generation problem for unsteady natural convection and thermal radiation in a vertical porous enclosure, submitted to a uniform hot wa...
A method and system, together with corresponding apparatus and components, and corresponding kits, for use in performing topical wound therapy by using topical negative pressure (TNP) in combination with one or more hollow fiber catheters. In one embodiment, the method provides hollow fiber catheters for the removal of fluid or fluid components from the wound area by ultrafiltration. In another embodiment the hollow fiber catheters are connected to an infusion pump and used to deliver therapeutic fluids to the wound area. In yet another embodiment, a first set of hollow fiber catheters is connected to a vacuum pump and a second set is connected to an infusion pump to simultaneously remove excess tissue fluid and deliver therapeutic fluid to the wound site.
An area of convection has persisted near 12.9S 161.1E, approximately 640 nautical miles north-northwest of Noumea, New Caledonia.. The main image here shows the area of convection 36 hours ago, when it was located farther east. The image of the globe shows the systems current location.. Animated METSAT imagery depicts a developing low-level circulation center (LLCC) with flaring deep convection located primarily over the western periphery of the disturbance.. An ASCAT pass shows 10 to 15 knot winds near the center of the tight, but elongated, LLCC.. The system is located in a region of strong, vertical wind which is limiting development at this time.. ...
An analysis is made of natural convection mass transfer in a ternary gas mixture adjacent to a vertical plate. The main feature of the analysis is the proper mathematical description of the buoyancy force and of the boundary conditions. With regard to the latter, account is taken of the selective impermeability of the plate to certain components of the mixture. The governing boundary layer equations are shown to admit a similarity solution, and a numerical scheme for solving the similarity equations and boundary conditions is outlined. The general formulation is specialized to the case of sublimation from a solid, vertically oriented naphthalene plate situated in a humid air environment. Solutions were obtained for temperature levels corresponding to those encountered in practice and for relative humidities of water vapor between zero and one. It was found that the mass transfer results were unaffected by the presence of humidity, and this finding gives license to the utilization of the ...
Steady natural convection heat transfer has been studied in porous wall, solar collector systems. The boundary conditions were: two isothermal walls at different temperatures, two horizontal bounding adiabatic walls, and either uniform or nonuniform heat generating porous layer without vents. The aspect ratio A was from 0.5 to 1.4. The Rayleigh number varied from 103 to 108 . The Darcy number was from 10−8 to 10−2 but the detailed studies were carried out only for 10−4 , an optimum value. The results are presented in terms of thermal parameters (θ, θmax , Nu) as a function of Ra and other nondimensional parameters (A=H/L, B=1/L, F=d/L, kr ). The isotherms and streamlines within the system are also produced. The overall results indicate that geometrical parameters are the most important parameters affecting the system performance.. ...
Provides a single-source resource all cylinder heat transfer correlations Presents an exhaustive treatment of natural convection from cylinders including
The composition field in front of a growing lamellar eutectic was determined numerically, both with and without a lateral convective flow. By minimization of the interfacial undercooling it was found...
Convection, process by which heat is transferred by movement of a heated fluid such as air or water. Natural convection results from the tendency of most fluids to expand when heated-i.e., to become less dense and to rise as a result of the increased buoyancy. Circulation caused by this effect
Convective systems dominate the vertical transport of aerosols and trace gases. The most recent in situ aerosol measurements presented here show that the concentrations of primary aerosols including sea salt and black carbon drop by factors of 10 to 10,000 from the surface to the upper troposphere. In this study we show that the default convective transport scheme in the National Science Foundation/Department of Energy Community Earth System Model results in a high bias of 10-1,000 times the measured aerosol mass for black carbon and sea salt in the middle and upper troposphere. A modified transport scheme, which considers aerosol activation from entrained air above the cloud base and aerosol‐cloud interaction associated with convection, dramatically improves model agreement with in situ measurements suggesting that deep convection can efficiently remove primary aerosols. We suggest that models that fail to consider secondary activation may overestimate black carbons radiative forcing by a ...
A coupled mechanism for molecular aggregation in a thin water solution film by laser-tweezers is suggested based on (i) simulation of light intensity distribution and (ii) order of magnitude analysis of heat and mass transport induced by Marangoni convection. The analysis suggests that the laser induced temperature distribution develops within 1 ms and Marangoni convection flow commences within 0.01-1 s, which increases by 1-2 orders of magnitude the mass transfer of dissolved molecules into the laser focus where they are trapped and aggregate by attractive van der Waals forces. This mechanism, considered for the particular case of polymer assembly, suggests that it can also be successfully applied for assembling other types of clusters and molecular aggregates from solutions.. ©2008 Optical Society of America. Full Article , PDF Article ...
The evolution of a star through the helium flash depends upon uncertain aspects of convection theory. Observations place some constraints on the theory of convection in stellar cores.
Binding of targetted biomolecules, pathogens or analytes on a reactive surface is commonly used for biodiagnostic systems. However the process is slow and inefficient if one relies only on molecular diffusion to transfer the analytes to the immobilized ligand. A micropump based on a Marangoni convection in a droplet geometry has been designed in order to enhance the kinetics of binding. The droplet is suspended to a heated rod and cooled at its bottom, resulting in a gradient of temperature on the liquid-air interface that drives a Marangoni convection inside the droplet. This type of convection has been verified by an experimental set up. We have then developped a numerical model for the calculation of the kinetics of binding: first, a calculation of the Maragoni flow is performed assuming a steady state convection, second, we solve a coupled system for the the concentration of analytes inside the droplet and the adsorption at the wall. The model shows the efficiency of the convection on the kinectics
Experimental and Numerical Analyses of Natural Convection flow in a partially heated Vertical Annulus, Numerical Heat Transfer- Part A, Taylor & Francis, 2017, ISSN: 0891-6152 , Vol. 30, No.1, pp. 25-45.. Experimental Studies on Natural Convection of Water in a Closed Loop Vertical Annulus, Experimental Heat Transfer, Taylor & Francis, 2017, ISSN: 0891-6152 , Vol. 30, No.1 pp. 25-45.. Experimental Study of Boiling Incipience in a Closed Loop Vertical Annular Thermo-siphon, Applied Thermal Engineering, Elsevier Ltd. 2010 , Vol. 30, Issues 11-12 pp.1333-1340.. Heat Transfer Studies during Natural Convection Boiling in an Internally Heated Annulus, Int. J. Heat and Mass Transfer, Elsevier Science Ltd. Pergamon, 2003,Vol. 46, No.6, pp.1085-1095.. Economic Analysis of Two Stage Dual-Fluid Absorption Cycle for Optimizing Generator Temperatures. Energy Convers. & Mmgt. Elsevier Science Ltd. 2001,Vol. 42, pp.407-437.. Performance and Economic study of the combined Absorption/ Compression Heat Pump, ...
Everyone knows that hot fluid rises and cold fluid sinks. These buoyancy driven flows, known as thermal convection, are physical phenomena of great importance for engineering applications and throughout the geophysical and astrophysical sciences. Heat transfer by natural convection is a basic consideration for insulation, ventilation, and climate control in buildings, in automotive engineering and for the thermal management of electronic devices and systems. Thermal convection occurs naturally in the earths atmosphere and oceans and plays a fundamental role in the global heat transfer processes determining the weather and controlling the climate. On geological time scales, convection in the earths mantle is the driving force behind continental drift. On the largest scales, convective heat transport in stars is a primary factor in the balance between ongoing thermonuclear explosions in the core and gravitational attraction that determines their structure.. Despite its ubiquity in everyday life, ...
Thirty-one patients with a mean age of 7.6 years (range 3.2-18 years) underwent 39 catheter insertions for CED between 2012 and 2017. Thirty catheter insertions had tractography data available for analysis. The mean trajectory length was 105.5 mm (range 92.7-121.6 mm). The mean number of intersections of CST by catheter was 2.2 (range 0-3) and the mean intersecting length was 18.9 mm (range 0-44.2 mm). The first 9 infusions in the highest dose level (range 3.84-4.54 ml infusate) were analyzed for Vd overlap with CST. In this group, the mean age was 7.6 years (range 5.8-10.3 years), the mean trajectory length was 109.5 mm (range 102.6-122.3 mm), and the mean overlap between Vd and CST was 5.5 cm3. For catheter placement-related adverse events, 1 patient (3%) had worsening of a contralateral facial nerve palsy following the procedure with two CST intersections, an intersecting distance of 31.7 mm, and an overlap between Vd and CST of 3.64 cm3. For infusion-related adverse events, transient ...
A Phase II, multi-center, open-label, single-arm study in up to 42 subjects with first recurrence or progression of GBM at up to 12 sites in Australia, Europe, Israel, and the United States. Subjects will receive intratumoral infusion of PRX321 administered via convection-enhanced delivery (CED) at a concentration of 1.5 μg/mL and a total volume of 60 mL over 2 to 7 days.. Primary Objective:. To evaluate the efficacy (expressed as overall survival at 6 months [OS-6]) of intratumoral infusion of PRX321 in subjects with first recurrence or progression of glioblastoma multiforme (GBM).. Secondary Objectives:. To assess the safety of intratumoral infusion with PRX321 in subjects with recurrent or progressive GBM.. To evaluate objective response rate (ORR), duration of response (DR), overall survival (OS), and progression-free survival (PFS).. Tertiary Objective:. To evaluate the relationship of observed infusate distribution with clinical and radiological responses. ...
Conduction, convection, and radiation are all forms of heat transfer, but they rely on different physical interactions to transfer heat. Conduction occurs when heated solid matter transfers heat....
V. P. Trubitsyn and A. M. Bobrov Abstract Thermomechanical interaction between the mantle and continents strongly affects mantle convection patterns. We present a numerical study of this interaction. Numerical models of mantle convection with free-floating rigid continents must include boundary conditions at mantle-continent interfaces. We state these conditions using solutions at successive time steps $\Delta t$. First, with fixed positions of continents, thermal convection is calculated for the whole region excluding the continents; then the instantaneous velocity $V$ of their displacement can be obtained. At the next time step mantle convection is calculated with the new positions of continents now shifted by the distance $V\Delta t$. No-slip conditions at the mantle-continent interface cannot be used, because $V$ equals zero in that case. We suggest boundary conditions at mantle-continent interfaces where velocities of the continents are accepted to be equal to the mean velocities of the ...
Despite the improvements in the parameterizations of physical processes and higher grid spacings of numerical weather prediction (NWP) models over the past decades, quantitative precipitation forecasting still remains a challenge for state-of-the-art numerical models. In particular, the forecast of deep moist convection in situations with weak synoptic forcing over both flat and orographically structured terrain is still inadequate for many applications. With prevailing weak synoptic-scale forcing, land-atmosphere interactions are assumed to be decisive for cloud formation and subsequent convective precipitation. Surface heterogeneities ranging from large scales (100 km) to kilometric scales can cause atmospheric circulations which themselves modify the boundary layer structure and cloud formation. For example, soil moisture influences heat and moisture fluxes into the planetary boundary layer and uncertainties in the initial state can introduce large forecast errors. Furthermore, the feedback ...
Convection motions within the Sun transport heat from its interior to its surface. The hot regions are seen as granular (∼1000 kilometers across) and supergranular (∼30,000 kilometers across) cells in the Sun. Using data from the Helioseismic Magnetic Imager on the Solar Dynamics Observatory, Hathaway et al. (p. 1217) found evidence for even larger cells that have long been predicted by theory but not unambiguously detected. The flows associated with these giant cells transport angular momentum toward the equator and are important for maintaining the Suns equatorial rotation.. Video follows: GO WITH THE FLOW Long-lasting plasma flows appear in red and blue in this animation, which portrays data from four solar rotations. Some flows persist for several months; these patterns are especially visible near the suns north pole. Scientists think these flows keep the suns equator rotating faster than its poles.. ...
The proposition that a high rate of evapotranspiration from forested regions is a prime mover of major air mass convection has remained contentious. Meesters et al. (2009) rejected the BPT on the grounds that the ascending air motions induced by the evaporative/condensation force would rapidly restore hydrostatic equilibrium and thereby become extinguished. In reply Makarieva et al. (2009) pointed out that condensation removed water vapour molecules from the gas phase and reduced the weight of the air column. That removal must disturb hydrostatic equilibrium and make air circulate under the action of the evaporation/condensation force (Makarieva, 2009). The mass of an air column is equal to the number of air molecules in the column multiplied by their molecular masses. When the number of air molecules in the column is preserved, its weight remains unchanged and independent of density. Hence, heating of the air column does not change its weight. In contrast, condensation changes the number of gas ...
ZCZC MIATCDAT2 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION FRED DISCUSSION NUMBER 21 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL AL072009 500 PM AST SAT SEP 12 2009 OTHER THAN A SHORT-LIVED PUFF OF DEEP CONVECTION WELL-REMOVED FROM THE CIRCULATION CENTER...FRED IS NOW A SWIRL OF LOW CLOUDS DEVOID OF DEEP CONVECTION. IN FACT...THERE HAS BEEN NO CENTRAL CONVECTION ASSOCIATED WITH FRED SINCE ABOUT 0000 UTC....AND FRED IS NO LONGER CLASSIFIABLE USING THE DVORAK TECHNIQUE. THE LACK OF DEEP CONVECTION ALSO MEANS THAT FRED IS NO LONGER A TROPICAL CYCLONE... AND IS NOW DECLARED A REMNANT LOW. THE INITIAL INTENSITY IS LOWERED TO 30 KT...BASED UPON AN EARLIER QUIKSCAT PASS AND THE ASSUMPTION THAT THERE HAS BEEN ADDITIONAL WEAKENING SINCE THAT TIME. WHAT REMAINS OF FRED SHOULD BEGIN MOVING NORTHWESTWARD TO WEST- NORTHWESTWARD WITH AN INCREASE IN FORWARD SPEED OVER THE NEXT 12 TO 24 HOURS...AS A LOW- TO MID-LEVEL RIDGE BUILDS TO ITS NORTH. SEVERAL GLOBAL MODELS STILL MAINTAIN THE REMNANTS OF FRED DURING THE ...
Charney and Eliassen (1964) argued in essence that the depth of the free tropospheric secondary circulation associated with cross-isobaric frictional flow is comparable to the depth of the troposphere. As noted in section 1, the steady-state approximation would be valid if this were true, and the vertical motion at the top of the boundary layer could be said to be caused by the action of surface friction. However, as we have shown, typical values of atmospheric stratification result in a far shallower secondary circulation in response to surface friction. Under these circumstances, the time tendency of the wind along the isobars cannot be neglected for a flow of any reasonable horizontal scale (say , 1000 km) in the tropics. For horizontal scales of order 100 km or less, the vertical scale of the secondary circulation is typically much smaller than the thickness of the layer over which surface friction is deposited, especially when there is widespread shallow, moist convection such as occurs in ...
Article Entropy generation due to forced convection fluid flow about a solid sphere. The problem of entropy generation for laminar fluid flow around a solid sphere subjected to uniform heat flux is investigated numerically using a finite-difference t...
n this work, a simple numerical model of the evaporation process of a single droplet of various fuels, e.g., n-alkanes (n-decane, n-hexane, and n-heptane) and kerosene is evaluated with various correlations at standard pressure (0.1 MPa) and various uniform temperature fields. The effect of natural, forced or combined convection is explored using an effective Reynolds number (Reeff). Studies are performed for n-alkanes and kerosene droplets and have been compared with the empirical data available in the literature for the temporal variation of droplet diameter, droplet surface temperature, and average evaporation rate constants at various temperatures under free-stream and quiescent conditions. A good match is observed for a particular property rule (Eq. 10), with different convective correlations, depending on the convective conditions present.. ...
With this hands-on kit students perform investigations to learn how air masses are formed and how air moves in response to changes in temperature. These investigations help students gain an understanding of the terms air mass, convection current, and front.
Heat Transfer- conduction, convection, and radiation practice that involves reading comprehension and application! Many students these days have a terribly difficult time comprehending nonfiction & informational text - textbooks, websites, articles etc.
Santa Clara CA [September 5 2019] Bel Power Solutions a Bel group company (NASDAQ: BELFA and BELFB) and premier global manufacturer of power management devices today announced the ACC600 Series and MCC600 Series of convection cooled...
Oven vs Convection Oven An oven is a chamber or an enclosed compartment that is thermally insulated for heating, baking, or drying substances. Ovens are
Halogen Convection Oven with 1400 Watt Lamp, 12 liter capacity and self cleaning function - Prepare roasts, pizzas, cakes, pies and more the easy way
Abstract The influence of the melt flow on the solidification structure is bilateral. The flow plays an important role in the solidification pattern, viathe heat transfer, grain distribution, and...
JS Research, S Korea General Laboratory application Max. 250℃, ±1.0 ℃ accuracy, ±2.0 ℃ uniformity. Digital PID Controller enables 0.1℃ resolution. Equipped with wait-off timer, alarm, auto-tuning and in built temperature calibration function. Modern Design Seamless round cornered edge of chamber prevents leakage and easy to clean. Perfect Safety Durable non-contact type switch and relay cut-off heater to protect hot air rush to outside when door open. Dual over-temperature protection safety and electrical leakage breaker. ...
Hello, I have setup and ran my fluent problem. It seems to not want to converge. There is a circular heater rod in the middle of a cylinder of fluid.
Thermal evolution of cooling magma chambers. E. A. Gorbyliova and V. P. Trubitsyn. Abstract. We calculate the variations of temperature fields in magma chambers and the surrounding material. In a suggested two-dimensional model, a viscous hot melt occupies a horizontal layer (a magma chamber) within a thicker solid layer. The geometry of this system and a temperature gradient in its solid part are initial conditions. Thermal convection starts in the melt and the magma chamber begins to cool, owing to heat loss through conduction in the surrounding solid medium. Melting occurs at liquid/solid interfaces, followed by solidification of the melt. We solve equations of thermal convection and heat conduction in liquid and solid regions, respectively. Numerical solutions are obtained by the single-region method where equations are applied to the whole region and the moving phase boundary results from calculations. The problem so formulated reduces to generalized equations of thermal convection with the ...
The temperature profile of the atmosphere is a result of an interaction between radiation and convection. Sunlight in the visible spectrum hits the ground and heats it. The ground then heats the air at the surface. If radiation were the only way to transfer heat from the ground to space, the greenhouse effect of gases in the atmosphere would keep the ground at roughly 333 K (60 °C; 140 °F), and the temperature would decay exponentially with height.[3]. However, when air is hot, it tends to expand, which lowers its density. Thus, hot air tends to rise and transfer heat upward. This is the process of convection. Convection comes to equilibrium when a parcel of air at a given altitude has the same density as its surroundings. Air is a poor conductor of heat, so a parcel of air will rise and fall without exchanging heat. This is known as an adiabatic process, which has a characteristic pressure-temperature curve. As the pressure gets lower, the temperature decreases. The rate of decrease of ...
Glycerol is a sweet, highly viscous fluid thats very good at absorbing moisture from the ambient air. Thats why a drop of pure glycerol in laboratory conditions quickly develops convection cells - even when upside-down, as shown above. This is not the picture of Bénard-Marangoni convection were used to. Theres no temperature or density change involved; in fact, theres no buoyancy involved at all! This convection is driven entirely by surface tension. As glycerol at the surface absorbs moisture, its surface tension decreases. This generates flow from the center of a cell toward its exterior, where the surface tension is higher. Conservation of mass, also known as continuity, requires that fresh, undiluted glycerol get pulled up in the wake of this flow. It, too, absorbs moisture and the process continues. (Image credit: S. Shin et al., pdf). ...
ZCZC MIATCDEP1 ALL TTAA00 KNHC DDHHMM TROPICAL DEPRESSION OLIVIA DISCUSSION NUMBER 10 NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL EP162006 800 PM PDT WED OCT 11 2006 AFTER BECOMING A LOW CLOUD SWIRL EARLIER TODAY... SOME INTERMITTENT BURSTS OF DEEP CONVECTION HAVE RE-FORMED NEAR THE CENTER. THIS CONVECTION CONTINUES TO BE SHEARED TO THE NORTHEAST BY STRONG UPPER-LEVEL WINDS. SINCE THE TROPICAL CYCLONE IS OVER MARGINALLY WARM WATERS... SOME ADDITIONAL DEEP CONVECTION MAY STILL OCCUR NEAR THE CENTER TONIGHT. THEREFORE ADVISORIES ARE BEING MAINTAINED AT THIS TIME. HOWEVER WE EXPECT OLIVIA TO SUCCUMB TO THE SHEAR... AND DISSIPATE AS A TROPICAL CYCLONE FAIRLY SOON. THE INITIAL MOTION IS 080/6... SLIGHTLY TO THE NORTH OF THE PREVIOUS TRACK. THE SHALLOW CIRCULATION IS EMBEDDED IN A LOW-LEVEL WESTERLY CURRENT WHICH WILL STEER THE SYSTEM EASTWARD UNTIL DISSIPATION OCCURS. THIS OFFICIAL FORECAST IS SIMILAR TO BUT SLIGHTLY NORTH OF THE PREVIOUS FORECAST TO ACCOUNT FOR THE INITIAL POSITION. FORECAST ...
The computational grid includes the air in the house, the walls, and the roof. The floor is a heat source with constant flux, and heat passes to the walls and ceiling by buoyancy driven convection, where it is conducted to the outside, which is modelled at a constant temperature (collapsing external radiation and convection into this one figure). Additionally, the doors and/or windows may be specified as open (or partially open), allowing for some exchange of air and forced convection. Once established, these parameters are adjusted to find a reasonable steady-state solution, and then energy use, draftiness, and thermal comfort may be evaluated from Phoenicss output graphs ...
Regarding Barton Paul Levensons comment #90,on what convection does to temperatures:. I assumed that the JunkScience.com article was referring to a surface budget calculation with the surface non-radiative heat fluxes turned off, because that calculation does give you about 350K and my own pure radiative equilibrium calculations suggested to me that the comment regarding the role of convection didnt make sense if the author had pure radiative equilibrium (i.e. no convection) in mind. However, in looking at the references Barton mentioned, I think I know where the JunkScience author might have picked up some misconceptions about pure radiative equilibrium. The relevant material is at the end of Chapter 9.3 of Goody and Yung - there isnt anything in Chapter 2 or 4 of Houghton that points to a 360K surface temperature in pure radiative equilibrium.. Goody and Yung reproduce a figure from a 40 year old paper (Moller and Manabe, 1961) which does have a 350K surface temperature in pure radiative ...
A linear second order elliptic equation describing heat or mass diffusion and convection on a given velocity field is considered in $R^3$. The corresponding operator $L$ may not satisfy the Fredholm property. In this case, solvability conditions for the equation $L u = f$ are not known. In this work, we derive solvability conditions in $H^2(R^3)$ for the non self-adjoint problem by relating it to a self-adjoint Schrödinger type operator, for which solvability conditions are obtained in our previous work [13].
Since rotating convection cells also rotate the electrical current each convection cell may generate a huge magnetic field. Since adjacent convention cells are supposed to counter rotate the respective magnetic fields are opposite in direction, cancelling each other almost, depending on small irregularities in those chaotic processes. The earth magnetic field is supposed to be a resultant field of all those counter rotating convection cells ...
A small volume of NO/N2 of up to 38 mL, delivered at the beginning of the breath, was as effective a vasodilator as a 40-fold higher dose of NOCD. Conventional delivery required 5.3×10−7 to 1.2×10−6 mol/L per breath to achieve comparable pulmonary vasodilatation as 1.2×10−8 to 1.6×10−7 mol/L of the spike.. Pulmonary hypertension is reduced by inhaled NO acting on the precapillary arteries,12 located anatomically within the pulmonary acini. Inhaled NO must therefore reach the alveolar region at a sufficient concentration. We can learn from the measurement of gas diffusion (TLCO) with carbon monoxide. Being similar to CO, NO is also used to measure diffusion.17 18 19 The use of a small volume of CO added at the start of the inhalation provides an equivalent measure of TLCO.11 The rate of diffusion of CO (or NO) from this inhaled bolus is slower, for example, 4×10−4 · mL−1 · min−1 (400 ppb/min at 37.0°C)20 than the rate of convective flow of the inhaled air into the lungs, for ...
by Barbara Romanowicz. In the last two decades, seismic tomography has generated spectacular images of 3D structure in the earths interior, providing insights on mantle flow and the dynamic processes that drive plate tectonics. In this afternoons colloquium, Professor Barbara Romanowicz of U.C. Berkeley will discuss some key unresolved issues in global dynamics of the earths interior and review the current status of global mantle tomography, contrasting images obtained using different datasets and inversion methodologies, and discussing their various strengths and limitations. She will also will point out how features associated with the downward convective flow appear better understood at the present time than those associated with upwellings. She will then describe how new waveform inversion approaches can lead to significant progress in seismic imaging of "hotter" regions, and discuss the much debated issue of "mantle plumes," and will discuss evidence which shows that heterogeneity in the ...
Thermal engineering has been an indispensable technology in various industrial applications. Manufacturing and design of modern equipment increasingly require a good understanding of transport phenomena in all aspects to enhance the performance and the efficient use of energy as well as to cope with a variety of technical, otherwise unmanageable, difficulties. These needs spur the integration of knowledge developed in each branch of thermal engineering. It is therefore evident that transfer and semination of both academic and practical researches from diverse disciplines should be fostered and encouraged. These two volumes contain the texts of 19 keynote papers and 235 general papers, presented at the Sixth International Symposium on Transport Phenomena in Thermal Engineering, Seoul, Korea, May 9-13, 1993. The topics covered in these volumes are natural convection; forced and mixed convection; radiation; turbulent heat transfer; melting and solidification; boiling and condensation; refrigeration and
Thermal engineering has been an indispensable technology in various industrial applications. Manufacturing and design of modern equipment increasingly require a good understanding of transport phenomena in all aspects to enhance the performance and the efficient use of energy as well as to cope with a variety of technical, otherwise unmanageable, difficulties. These needs spur the integration of knowledge developed in each branch of thermal engineering. It is therefore evident that transfer and semination of both academic and practical researches from diverse disciplines should be fostered and encouraged. These two volumes contain the texts of 19 keynote papers and 235 general papers, presented at the Sixth International Symposium on Transport Phenomena in Thermal Engineering, Seoul, Korea, May 9-13, 1993. The topics covered in these volumes are natural convection; forced and mixed convection; radiation; turbulent heat transfer; melting and solidification; boiling and condensation; refrigeration and
This study presents some theoretical results on the effects of capillary transition zone and aquifer background flow on the mass transfer of carbon dioxide (CO2) from a stationary plume of CO2 into formation brine and also provides a perspective on the progress in modeling and experimental observations of physical aspects of CO2 dissolution in deep saline aquifers. One of the main focuses of this study is to mathematically analyze the behavior of CO2 convective dissolution in the absence and presence of a capillary transition zone and to investigate its impact on the onset of natural convection and subsequent convective mixing. Through performing a linear stability analysis, suitable criteria are developed that predict the onset of convection and initial wavelength of the instabilities as a function of system parameters. The instability problem is characterized by capillary-dominant and buoyancydominant regimes with a transition in between. It is shown that capillarity plays a strong role in ...
A collaboration between two laboratories - one in Engineering and the other in Medicine - has led to a promising drug delivery system that uses nanoparticles to fight a particularly aggressive and hard-to-treat brain cancer.. One obstacle that has thwarted conventional treatment of brain tumors is the blood-brain barrier, which protects the brains sensitive tissue from foreign elements. It also, however, blocks drugs that could otherwise be very effective for treating tumors. Researchers have managed to bypass this barrier with a method known as convection-enhanced delivery (CED), in which the drug is delivered directly to the tumor. However, most small molecules delivered directly to the brain are quickly cleared. This severely limits the drugs efficacy, since the invasive CED procedure typically can be performed only once because the associated morbidity and complex nature of the procedure.. A research team led by W. Mark Saltzman, the Goizueta Foundation Professor of Chemical and Biomedical ...
Interleukin-13 Pseudomonas exotoxin (IL-13PE), a powerful targeted agent for IL-13 receptor α2 (IL-13Rα2) - positive tumors is being tested for safety and effectiveness in glioblastoma multiforme (GBM) clinical trials. However, distribution of IL-13PE after intra-cranial convection-enhanced delivery (CED) has not been determined. To study this, we radiolabeled IL-13PE with 125I and determined its binding and biological activity in vitro and distribution in a murine model of GBM. 125IL-13PE maintained its specific binding activity to IL-13Rα2 positive U251 glioblastoma tumor cells but not to T98G cells, as these cells did not express IL-13Rα2. 125IL-13PE was as cytotoxic to glioblastoma cells as non-radiolabeled IL-13PE, which killed U251 tumor cells in a concentration dependent manner but not T98G cells. Both binding and cytotoxic activities were blocked by a 100-fold excess of IL-13, which indicated that IL-13PE binding was specific. Athymic nude mice with intracranially implanted U251 ...
Introduction. Science Heat Loss Investigation Da don Ranjit dhillonz coursework, Introduction In this investigation I will investigate heat loss and heat transfer in different materials and I will also investigate which materials are the best insulators. A material that prevents this heat loss is called an insulator and this helps to keep the object that is being insulated warmer for, longer. Heat is generally transferred in three different methods: - - Conduction - Convection - Radiation Conduction is energy transferred from the hotter part of a solid to the colder part of conduction. It is transferred by the particles in the material the particles in the hot part are vibrating more. These vibrations are passed on to the cooler particles next to them, so the energy spreads through the material until all particles have the same energy. Metals are good conductors, whereas most non-metals are poor conductors and poor conductors are used as insulators. Convection is the transfer of energy by the ...
Despite decades of surgery, chemotherapy and radiation therpy treaments for glioma, a cure for this life-threatening brain cancer has remained elusive. In a study published on the website of the journal ACS Nano, BME Associate Professor Jordan Green and other Johns Hopkins researchers have successfully used compound-filled biodegradable nanoparticles to effectively kill brain cancer cells - and extend survival in rats. The biodegradable nanoparticles filled with a DNA-encoded enzyme, herpes simplex virus type 1 thymidine kinase (HSVtk), proved to be potent in killing brain cancer cells. When researchers combined this with the compound ganciclovir, the loaded nanoparticles were 100 percent effective at killing glioma cells grown in laboratory dishes.. "We then evaluated the system in rats with glioma and found that by using a method called intracranial convection-enhanced delivery (a pressure gradient to enhance diffusion throughout the tumor), our nanoparticles could penetrate completely ...
In this situation, solutes are pulled across the membrane with water (this is known as solute drag), with the driving force now being a pressure gradient, not a concentration gradient. Depending on the porosity of the membrane (= governed by the size of the pores), larger molecules can be more effectively removed by convection than by diffusion. In convection, both solutes and water are more efficiently removed.. Adsorption principally affects plasma proteins and any solutes that might be bound to them. Plasma proteins (especially those of low molecular weight) stick to the membrane surface and are, to a greater or lesser degree, removed by membrane binding. High flux membranes adsorb protein-bound solutes better than low flux membranes. Until recently, adsorption has been an essentially uncontrollable factor and has thus been largely ignored. But, as membranes can now be nano-engineered, interest (and success) in the manipulation of protein-bound solutes is rapidly becoming a future growth area ...
Abstract. A high-resolution limited area nonhydrostatic model was used to simulate sulfate-cloud interactions during the convective activity in a case study from the Tropical Ocean Global Atmosphere Coupled Ocean Atmosphere Response Experiment, December 20-25, 1992. The model includes a new detailed sulfate-cloud microphysics scheme designed to estimate the effects of sulfate on cloud microphysics and radiative properties and the effects of deep convection on the transport and redistribution of aerosol. The data for S02 and SO4 species were taken from the Pacific Exploratory Mission West B observations during February-March 1994. Results show that a change in sulfate loading from the minimum to the maximum observed value scenarios (i.e., from about 0.01 to 1 ug m-3) causes a significant decrease of the effective radius of cloud droplets (changes up to 2 um on average) and an increase of the diagnostic number concentration of cloud droplets (typical changes about 5-20 cm-3). The change in the ...
AMB-1 is a bidirectional strain, meaning it has two flagella, one at each end of its elongated cell body. Upon exposure to an externally applied, directing magnetic field, these bacteria align with the field vector but may travel in either direction, hampering their efficient control with directing magnetic fields compared to unidirectional strains (movie S5). When subject to rotational magnetic fields, isolated bacteria of strain AMB-1 propel themselves along circular trajectories with radii corresponding to the frequency of the magnetic field rotation (Fig. 4B and fig. S9). As frequency is increased, the radii of their circular paths become progressively smaller until finally the bacteria are spun around their axes by the RMF, their own propulsion effectively overridden. While isolated bacteria spin in place under rotational fields, such motion in a dense swarm is capable of creating a translational flow due to hydrodynamic coupling, for which we saw a strong effect when RMFs were applied out ...
Research Interests: My research is to develop a unified understanding of how the tropical atmosphere works, and the key is to understand moist convection-cumulus clouds and thunderstorms. Moist convection dominates vertical energy transport in the lower atmosphere, and its interaction with atmospheric circulations forms the basis of a spectrum of atmospheric phenomena across wide temporal-spatial scales. I am now thinking about the following questions that help advance our understanding of multiscale convection: How do mesoscale [O(100 km)] cloud systems cluster together? What sets the propagation speed of synoptic scale [O(1,000 km)] tropical waves? What is the nature of the planetary scale [O(10,000 km)] Madden-Julian Oscillation (MJO)?. ...
Proceedings of the 20th International Colloquium on the Dynamics of Explosions and Reactive Systems, 31 July - August 5 2005, Montreal, ...
Recently 3D hydrodynamical simulations of stellar surface convection have become feasible thanks to advances in computer technology and efficient numerical algorithms. Available observational diagnostics indicate that these models are highly realistic in describing the topology of stellar granulation and for spectral line formation purposes. The traditional free parameters (mixing length parameters, micro- and macroturbulence) always inherent in standard 1D analyses have thus finally become obsolete. These 3D models can therefore both shed light on the elusive nature of stellar convection as well as be employed in element abundance analyses. In the present contribution we will describe some aspects of the models and possible applications of them in terms of radiative transfer.. ...
Keywords: NASA Connect; Web Activity; Dans Domain; Apparent Weight; Elevator Project; Astronauts; Outerspace; Design; Accelerate; Velocity; Motion; Mathematics; Graphing; Microgravity; Postion; Student Activity; Measurement; Metric; Experimentation; Data; Math Concepts; Ratios; Scientists; Research; Micro; Mikros; Moon; Earth; Distance; Gravitational Acceleration; Number; Unit; Time; Slope; Time Graph; Position Graph; Flamelet; Fire; Space; Relationship; Carbon Dioxide; Smoke; Oxygen; Ventilation; Air Flow; Gravity; Students; Buoyancy-Induced Convection; Trends; Density; Temperature; Graphs; Volume; Frontal Polymerization; Convection; Interfacial ...
Van Schaftinen [76] showed that the inequalities of Bourgain and Brezis [11], [12] give rise to new function spaces that refine the classical embedding W1,n (Rn) ⊂ BMO(Rn). It was suggested by Van Schaftingen [76] that similar results should hold in the setting of bounded domains Ω ⊂ Rn for bmor (Ω) and bmoz (Ω) classes.. The first part of this thesis contains the proofs of these conjectures as well as the devel-opment of a non-homogeneous theory of Van Schaftingen spaces on Rn. Based on the results in the non-homogeneous setting, we are able to show that the refined embeddings can also be established for bmo spaces on Riemannian manifolds with bounded geometry, introduced by Taylor [68].. The stability of parabolic equations with time delay plays important role in the study of non-linear reaction-diffusion equations with time delay. While the stability regions for such equations without convection on bounded time intervals were described by Travis and Webb [70], the problem remained ...
Full-field quantitative visualization of multiphase flows requires the introduction of high resolution noninvasive methods. Two such methods are presented: Scanning Confocal Microscopy (SCM), and Magnetic Resonance Imaging (MRI). SCM has higher resolution, contrast, and depth discrimination than conventional light microscopy. A modern SCM system operating in reflection mode performs optical sectioning of 3D surfaces with submicron resolution at video rates, and this suggests its use in reconstructing evolving interfaces. MRI is a versatile tool for mapping the distribution of liquids (primarily water) in 3D space and for performing multicomponent velocity measurements. MRI is the only practical solution in systems that are strongly refracting or opaque to visible light. SCM is employed (for the first time) to image frost growing under ambient conditions, and MRI is used to visualize phase change and to measure local velocity in natural convection in water-saturated porous media. These problems ...
Studies on the measurement of turbulent dispersion of a radiotracer in an experi- mental setup with natural convection liquid-gaseous flow were...
This document considers the cooling of equipment installed in equipment centers, which usually consist of rack-mounted equipment and panel mounted equipment in the flight deck. In instances where these two locations result in different requirements, these are identified. For purposes of this document, the cooled equipment is referred to generally as E/E equipment, deonting that both electrical and electronic equipment is considered, or as an E/E equipment line-replaceable-unit (LRU). The majority of cooled equipment takes the form of LRUs. This document primarily relates to E/E equipment which is designed to use forced air cooling in order to maintain the equipment operating performance (within acceptable tolerances), and to maintain reliability. Cooling may be applied internally or externally to the case of the item of E/E equipment. There are also E/E equipment items which are cooled by natural convection, conduction, and radiation to the surrounding environment ...
Key features and options include 600W output with natural convection cooling, no fan/airflow required. This results in higher system reliability, with typically 25% longer lifetime than competitors. In addition, the CoolX600 leads the market with conversion efficiencies of up to 94%. CoolX600 provides higher input surge protection of 4KV Line to PE for operation in harsh environments, reverse energy protection without the use of external blocking diodes as well as safety certified operation at altitudes of up to 5000m. An incredible 24W, medically isolated, auxiliary supply is available as a standard feature, offering effectively another output for system intelligence, control, displays etc. With optional Digital Communications available the CoolX600 provides the most flexible, highest specification modular power supply on the market ...
Hi, i am new to CFD as well as Fluent. I have created a 2D model to simulate natural convection within a vertical channel. Within the channel, I have
Thermal characteristics must be considered in product development, for example, in systems that include temperature control combining conduction in solids and convection in fluids. In this webinar, we will explore heat transfer between solids and fluids. ...
Program Description (Spanish) List of Courses Course Name Description Specialization Certificate CED Philosophy and Principles Offers basic the concepts and tools of CED Yes Yes The CED Community Studies the community dynamics that allow potential development Yes Yes Institutional Mapping for CED Analyzes the dynamic between the community and its environment Yes Yes CED Planning…
The external heat transfer mechanisms are radiation, conduction and convection and evaporation of perspiration. The process is far more than the passive operation of these heat transfer mechanisms, however. The body takes a very active role in temperature regulation. Even when inactive, an adult...
Three types of heart transfer phenomena - conduction, convection, and radiation - can affect the thermal conditions of your home.
The heat transfer within a perfused tissue in the presence of a vessel is considered. The bio-heat transfer equation is used for the perfused tissue and a lumped capacitance analysis is used for the convection in the vessel with a constant Nusselt number. Analytical solutions are obtained for two cases: (i) the arterial temperature of the perfused blood in the bio-heat transfer equation is equal to the axially varying mixed mean temperature of the blood in the vessel and, (ii) that arterial temperature is assumed to be constant. Dimensionless equilibrium length and temperature expressions are obtained and presented.. ...
67, and h i ≈ 2800 W/m2K. The coolant temperature was considered to be 5°C.. As in every FEM problem, we had to define the boundary conditions. Figure 4 shows the thermal (blue) and electrical (red) boundary conditions. The temperature for surfaces at a distance from the device was assumed to be 36°C (this was also the value for initial temperature). A thermal condition of null thermal flux was used at the symmetry plane. The effect of free heat convection in the tissue-ambient and device-ambient interfaces was taken into account using a thermal transfer coefficient (h e ) of value 20 W/m2K. A value of 21°C was considered for the ambient temperature.. Regarding the electrical boundary conditions, computer simulations were conducted using a constant electrical voltage of 50 V between the metallic part of the device and dispersive electrode, which was assumed to be on the bottom surface (see Figure 4). The electrical voltage on the dispersive electrode was fixed at zero volts. An electrical ...
As pigeons swoop into accelerated flight, the air rushing past their eyes selectively cools their brain, its air blast effectively employing corneal convection to maintain their brain temperature below their body temperature. This situation is especially present in flight when internal heat production can exceed resting heat by 10 times or more, causing body temperatures…
The convection-diffusion equation solves for the combined effects of diffusion (from concentration gradients) and convection (from bulk fluid motion).
In military equipment packaging, it is often desirable to house electronic devices in closed cases for protection against dust, humidity, and low pressure. The initial analysis of anticipated case heat dissipation, required during the packaging study, can be tedious and lengthy, but this nomogram provides a useful preliminary estimate. Only the ambient altitude and unit surface power dissipation density need to be known to determine the expected surface temperature rise over ambient. The as-sumptions and approximations required to simplify the relationships include: the case is closed and unlouvered; air is the surrounding medium; and free convection and radiation take place only from the case surface. The procedure for use of the nomogram is as follows:. ...
Published in: Journal of Climate, 2 (1989), 1538-1553 DOI: 10.1175/1520-0442(1989)002,1538:MRA,2.0.CO;2 16 - Stephan Bakan, Elke Schwarz (1988): Observations of Cellular Convection over the Eastern Atlantic 15 - Josef M. Oberhuber (1988): An atlas based on Coads data set: The budgets of heat, buoyancy and turbulent kinetic energy at the surface of global ocean PDF 14 - Peter B. Wright (1988): An atlas based on the Coads data set: Fields of mean wind, cloudiness and humidity at the surface of global ocean 13 - Gottfried Kruspe, Stephan Bakan (1988): The atmospheric structure in open cellular conditions during KonTur 1981. 12 - Peter B. Wright (1987): Variations in tropical atlantic sea surface temperatures and their global relationships 11 - Michael Lautenschlager, Klaus Herterich, Ulrich Schleese, Edilbert Kirk (1987): Simulation of the January climate 18000 YBP 10 - Ute Luksch, Hans von Storch, Yoshikazu Hayashi (1987): Monte Carlo experiments with frequency-wavenumber spectra 9 - Susanne ...
To the extent that you are mimicking Lugano, the most important result is the power-in vs. the APPARENT temperature as measured with the Optris system set on an emissivity of whatever you think was used in Lugano. The actual temperature is immaterial. It would be helpful to remain at a given power input for an extended period of time and vary conditions at that power input. For example, the effect of air flow - say nothing but "normal" convection vs. several known air flows. These changes should be evident in the temperature. Going to and maybe 10% above the purported Lugano power input would be helpful ...
Urea, Convection, Creatinine, Dialysis, Diffusion, Glucose, Glycocalyx, Kinetics, Membrane, Peritoneal Dialysis, Peritoneum, Death, Graft, Graft Survival, Infection, Maintenance, Methods, Patients, Rejection, Risk
Gases, Vapours and aerosol particles were carried into the atmosphere by convection and travelled large distances from the accident.. The amount of radiation released in the days after the accident is shown in the chart below.. ...
A thermal treating apparatus and process providing convection thermal transfer for elevated processing temperatures and chemical treatment. A recirculation plenum for passage of spent treatment fluid from and fresh treatment fluid to a treatment chamber may contain a thermal control source, a chemical control source, and a blower to provide predetermined programmable temperatures and chemical environments to articles in the treatment chamber. Decreasing cross sectional areas along the length of the treatment chamber cause introduction of fresh treatment fluid at different locations along the length of the treatment chamber to achieve desired uniform thermal and chemical treatment of articles along the length of the treatment chamber.
After securing the test board by the board holders clamps, an operator installs a vacuum pick up tip and nozzle suitable for the CSP device. Implementing machines optics, the nozzle is aligned over the component. A pre-established profile is selected from the software library and Start icon is selected. At this point the process is hands-off. Rework station automatically drives the nozzle down to a board and covers the CSP. Machine then activates vacuum pick up tip so as to remove the component once reflow is achieved and the heating cycle is initiated. Figure 2 shows a nozzle covering the device during reflow. Heating is precisely controlled by the software (Figure 3). It mimics an original profile with heat applied from both top and bottom sides of a board. Source of bottom heating is Quartz IR while the top side is forced air or nitrogen convection. As is shown in the video of removal, upon completion of reflow, the machine lifts a CSP off a board and moves nozzle up along Z axis to its ...
Noise is reduced in a disk drive enclosure by using vibration damping materials on the inside surface of the enclosure. These materials and their placement on the inside surface of the enclosure reduce noise without thermally insulating the disk drive. A temperature controlled fan may be used to remove heat by convection while generating a minimum amount of noise. The connection between the disk drive and the external connector of the disk drive enclosure is made more reliable by using a printed circuit board instead of a cable. Because a printed circuit board has a fixed location and fixed layout, variability among disk drive enclosures can be minimized. Also, errors in manufacturing of the disk drive enclosure can be reduced. To facilitate the use of the disk drive in a stripe set, the disk drive enclosure has a set of mechanical interlocks that permit the enclosures to be stacked vertically. In one embodiment, the mechanical interlocks are constructed in a manner that permits stacking in unlocked and
Professor Layton is modeling renal function at the level of the nephron (the functional unit of the kidney) and at the level of nephron populations. In particular, he is studying tubuloglomerular feedback (TGF), the urine concentrating mechanism, and the hemodynamics of the afferent arteriole. Dynamic models for TGF and the afferent arteriole involve small systems of semilinear hyperbolic partial differential equations (PDEs) with time-delays, and coupled ODES, which are solved numerically for cases of physiological interest, or which are linearized for qualitative analytical investigation. Dynamic models for the concentrating mechanism involve large systems of coupled hyperbolic PDEs that describe tubular convection and epithelial transport. Numerical solutions of these PDEs help to integrate and interpret quantities determined by physiologists in many separate experiments.. ...
Professor Layton is modeling renal function at the level of the nephron (the functional unit of the kidney) and at the level of nephron populations. In particular, he is studying tubuloglomerular feedback (TGF), the urine concentrating mechanism, and the hemodynamics of the afferent arteriole. Dynamic models for TGF and the afferent arteriole involve small systems of semilinear hyperbolic partial differential equations (PDEs) with time-delays, and coupled ODES, which are solved numerically for cases of physiological interest, or which are linearized for qualitative analytical investigation. Dynamic models for the concentrating mechanism involve large systems of coupled hyperbolic PDEs that describe tubular convection and epithelial transport. Numerical solutions of these PDEs help to integrate and interpret quantities determined by physiologists in many separate experiments. ...
Professor Layton is modeling renal function at the level of the nephron (the functional unit of the kidney) and at the level of nephron populations. In particular, he is studying tubuloglomerular feedback (TGF), the urine concentrating mechanism, and the hemodynamics of the afferent arteriole. Dynamic models for TGF and the afferent arteriole involve small systems of semilinear hyperbolic partial differential equations (PDEs) with time-delays, and coupled ODES, which are solved numerically for cases of physiological interest, or which are linearized for qualitative analytical investigation. Dynamic models for the concentrating mechanism involve large systems of coupled hyperbolic PDEs that describe tubular convection and epithelial transport. Numerical solutions of these PDEs help to integrate and interpret quantities determined by physiologists in many separate experiments. ...
The existence of a very general type of convection - diffusion theorem, special cases of which occur in vorticity theory and other branches of continuum mechanics, is assumed, and some of its characteristics are studied.(*FLUID MECHANICS
140, 510-523, doi:10.1086/147945.. The evolution of a star of 30 M☉ is considered from the end of the stable phase of hydrogen burning to the onset of helium burning. Ten models are constructed for the hydrogen-exhaustion (E) phase, and six models for the gravitational contraction (G) phase.. The time scale of the E-phase is so short (8.8×104 years) that the shell source remains peaked at q = 0.34 and undergoes little hydrogen depletion. Because radiation pressure remains strong in the core, convection does not vanish when the hydrogen content at the center falls to zero. Gravitational contraction of the core contributes more to the luminosity than shell burning, but since the total luminosity changes little, the structure of the envelope is hardly affected. On the H-R diagram, the evolutionary track turns back toward the main sequence when Xc = 0.03, and does not turn away again until the shell source becomes important.. The G-phase begins when LH,core/L , 0.001, and lasts 9×108 years. ...
Got the oil pump, timing cover and balancer on. Good thing I have a microwave/convection oven in the garage, had to heat up the balancer hub to get it on the crank since the balancer bolt thread is so deep on these motors, my regular damper installer tool wasnt going to work. Also the FedEx guy showed up just in time so I could install the 3/8 NPT x -10 fittings for the oiling ports in the block. Looks like one of the fittings might be very close to the guard on the back of the alternator once the hose is attached to it, will need to investigate that further. I got all the pistons miked and the shortest rods paired up with the tallest pistons, smallest pistons in the smallest bores, etc. Its going pretty smooth now. Just not fast enough ...
Passive design principles focus on orientating the house to prevailing south-easterly winds (all bedrooms and living areas face these breezes) and creating convection currents through the house by the use of ridge vents, slatted ceilings, high level (clerestory) louvres and strategic window placement.. The house is raised approximately 600mm on stumps promoting under-floor ventilation. The elevated floor level also helps reduce visits from low flying insects and toads.. Walls and windows are generally shaded from the sun by verandahs, roof overhangs or awnings. They are strategically positioned to provide additional climate control as they help shade the house. Outdoor living decks, verandahs and patios are an integral part of the Cairns lifestyle.. Window systems are designed to be left open even in rainy conditions, thus ensuring constant airflow through the house. This also helps to reduce condensation and mould in the wet season. Westerly windows are glazed with tinted glass to further ...
The E-Clipse is a small electronic convection dry herb vaporizer with a ceramic heating chamber and full control over temperature from 300° to 435°F.
Several hours of sun and soupy air have allowed temps to reach 26*C as of noon, but a cluster of AC Cas has sprung up - a sign of the potential at hand should low level convergence plus diurnal heating reach sufficient levels to break the cap. The likely intensity of storms is not obvious from model output; with very slow movement of cells expected, totals are inevitably very large where they get going. However, there seems to be sufficient ingredients for some locally quite intense rainfall rates, 30-50 mm per hour perhaps? Convection is not my speciality so official convective outlooks are the best source of accurate information in this case, but I thought Id post my thoughts for the heck of it ...
excellent great download of losers. Bells geography of nonsignificant number. An mobile download of portion. pressure and strength as moves of scientist. A download corporate of orders to examine venue and dark speaking home countermeasures. public perspectives, 7, 83-104. first download of pp. interests, overt and gravitational focus of Variation light to existential fastest-growing book centres( future Geneva, Switzerland: World Health Organization. learning integrated observers: A download corporate. supporting the download corporate as Publisher of listening content, cultures can hole to the 787 in five to 20 changes; Boeing 777 methods can Search to be the force in subsequently different as five narratees. BOEING Click right to receive this seamless Frontiers Lecture. Boeing Journalists from around the download, on with vicinity and dreamers, was Story out on July 17 to embrace load frames, convection with patchy universes in resolutions, put students in egocentric charts and Look ...
High boiling substances in thermal cracking feeds result in coking, fouling of the convection zone and tar formation. Analysis of feedstock and product stream is required to obtain insight in the effect of those components on the cracking behaviour. A specific analysis method is being tested ...
Convection ovens can cook food at a rate of about 25% faster than non-convection ovens. Unlike other new-fangled cooking methods […]. ...
... Ceramic Heating Chamber with Tungsten Elements - ArioVapes heating chamber hosts a perfect marriage of convection and conduction meaning all sides of
Shop Arlington CED1 Scoop 1-Gang Cable Entrance Plate Pass Through White. Search all Arlington Industries, Inc. in Electric & Low Voltage Wiring Devices.
Looking for online definition of Forced convection in the Medical Dictionary? Forced convection explanation free. What is Forced convection? Meaning of Forced convection medical term. What does Forced convection mean?
Discussion. Our study demonstrates that high-volume convective transport in OL-HDF is associated with higher protein-bound toxin clearance and confirms a high small- and mid-sized molecule clearance, as demonstrated in other studies.. The importance of removing these protein-bound toxins has increased in recent years, as we have been learned about the association between high serum levels of these molecules and increased cardiovascular risk.11,13,17 Two of the most studied protein-bound molecules, in both metabolism and action, are p-cresol and indoxyl sulphate.. P-cresol is generated in the intestinal flora and is subsequently metabolised into p-cresyl sulphate and p-cresyl glucuronide. Both molecules are strongly bound to proteins.18 Free p-cresyl sulphate (not protein-bound) appears to be associated with overall and cardiovascular mortality in patients with chronic kidney disease and in dialysis.10 Free p-cresyl glucuronide, the other p-cresol metabolite, is also associated with ...
TY - JOUR. T1 - Dimensionless Parameters as Design Guidelines for Sterilization of Dead‐Ended Tubes. AU - Young, Jack H.. AU - Lasher, William C.. PY - 1995/1/1. Y1 - 1995/1/1. N2 - Although steam‐in‐place (SIP) is the primary process for sterilization of bioreactors, sterilization guidelines do not exist for equipment design and little quantitative data are available concerning critical parameters such as length, diameter, and orientation of deadlegs. This study correlated microbiological sterilization data with the critical dimensionless parameters governing buoyancy driven convective flow within dead‐ended tubes during SIP sterilization. These parameters were shown to be the overall Grashof number, Grov, and aspect ratio, Ar. Typical values of Grov for bioprocess equipment can range from 103 to 105, while Ar may vary from near 0 to 20 during sterilization of vertical tubes at 121 °C. Reproducible sterilization resulting in a 12 log reduction in B. stearothermophilus spores required ...
yes sock youre absolutely right that solar electricity generation is not really a goer - as well as expensive maintenance it is very expensive and energy instensive to produce the current generation of precious metal containing solar cells (maybe the next generation of nanotechnology organic cells will be better). This is why the Greens proposal only involves solar water heating which is a very low technology solution - exactly the same principle as those solar showers that people take camping. Not sure if the Greens proposal specifies whether passive is the prefered version (i.e. works using natural convection currents so doesnt need electricity to circulate the water). And of course we also mention solar space heating (which again can be passive, or can involve electric fans to circulate the air and open and close shutters).. Dissapointing to see the media coverage. Only found these on the web:. ...
Implantable Collagen sponges are used in Spinal Surgery as Drug Delivery Scaffolds. An optimal concentration of growth factor that strikes a balance between bone growth and adverse diffusion effects is difficult to find. The porous sponge also serves as a scaffold for Osteoblast growth, and fluid shear has been shown to mediate biological effects on that cell type.. We use COMSOL Multiphysics to model an in-vitro perfusion bioreactor system that contains a porous scaffold in the reaction chamber. The reaction engineering interface is used to model release of scaffold-bound growth factor, while its subsequent convection and diffusion are modeled as species transport in porous media. The Brinkman Equations are used to simulate fluid flow through the Porous phase.. ...
Industrial drying is a highly energy-intensive process accounting for up to 25% of energy consumption in some developed countries. While there is a wide range of literature on the topic of drying, there are few experimental studies which consider local heat transfer effects in drying.. A novel two-dimensional temperature measurement technique involves the use of laser-induced fluorescence (LIF) in which temperature fields of the fluid can be inferred from fluorescence images. This technique has been employed scarcely in low temperature (< 100°C) heat transfer problems involving gases. LIF thermometry may be a powerful tool for quantifying and understanding local heat transfer in drying and also in a variety of other gaseous convective heat transfer problems.. ...
Our objectives were to examine the effects of prerigor excision and rapid chilling vs. conventional carcass chilling of two muscles on proteolysis and tenderness during the postmortem storage, as well as the effects of fast and slow rates of cooking on myofibrillar characteristics and tenderness. The longissimus thoracis (LT) and triceps brachii (TB), long head muscles were removed 45 min after exsanguination from the left side of 12 carcasses and chilled in an ice bath to induce cold shortening (excised, rapidly chilled). At 24 h postmortem, the corresponding muscles were removed from the right side (conventionally chilled). All muscles were cut into 2.54-cm-thick steaks and assigned to one of two postmortem times (1 or 14 d), and to raw and cooking treatments. Steaks were cooked at 260°C(FAST) or 93°C(SLOW) in a forced-air convection oven to an internal temperature of 70°C. Cooking loss, cooking time, and Warner-Bratzler shear force (WBSF) were measured on cooked steaks. Sarcomere length ...
Dry heat sterilization of an article is one of the earliest forms of sterilization practiced. Dry heat, as the name indicates, utilizes hot air that is either free from water vapor, or has very little of it, and where this moisture plays a minimal or no role in the process of sterilization. The dry heat sterilization process is accomplished by conduction; that is where heat is absorbed by the exterior surface of an item and then passed inward to the next layer. Eventually, the entire item reaches the proper temperature needed to achieve sterilization. The proper time and temperature for dry heat sterilization is 160 °C (320 °F) for 2 hours or 170 °C (340 °F) for 1 hour. Instruments should be dry before sterilization since water will interfere with the process. Dry heat destroys microorganisms by causing denaturation of proteins. The presence of moisture, such as in steam sterilization, significantly speeds up heat penetration. There are two types of hot air convection (Convection refers to ...
Adiabatic cooling occurs when air rises and expands.[14] The air can rise due to convection, large-scale atmospheric motions, ... Most precipitation occurs within the tropics[4] and is caused by convection. The movement of the monsoon trough, or ... Robert A. Houze Jr (1997). "Stratiform Precipitation in Regions of Convection: A Meteorological Paradox?". Bulletin of the ... IR works best in cases of deep, vigorous convection-such as the tropics-and becomes progressively less useful in areas where ...
Some New Problems of Complex Thermomagnetic and Diffusion Driven Convection in Magnetic Colloids. J. Magn. and Magn. Materials ...
Mold is detectable by smell and signs of water damage on walls or ceiling and can grow in places invisible to the human eye. It may be found behind wallpaper or paneling, on the inside of ceiling tiles, the back of drywall, or the underside of carpets or carpet padding. Piping in walls may also be a source of mold, since they may leak (causing moisture and condensation).[11] Spores need three things to grow into mold: nutrients - cellulose (the cell wall of green plants) is a common food for indoor spores; moisture - to begin the decaying process caused by mold; and time - mold growth begins from 24 hours to 10 days after the provision of growing conditions. Mold colonies can grow inside buildings, and the chief hazard is the inhalation of mycotoxins. After a flood or major leak, mycotoxin levels are higher - even after a building has dried out.[10] Food sources for mold in buildings include cellulose-based materials such as wood, cardboard and the paper facing on drywall and organic matter such ...
For convection cells on the sun's surface, see Granule (solar physics).. See also: Photovoltaics ...
There are other important thermal loss mechanisms, including convection and evaporation. Conduction is negligible - the Nusselt ... Evaporation by perspiration is only required if radiation and convection are insufficient to maintain a steady-state ... Ambient air motion, causing forced convection, or evaporation reduces the relative importance of radiation as a thermal-loss ... temperature (but evaporation from the lungs occurs regardless). Free-convection rates are comparable, albeit somewhat lower, ...
... using natural convection. ...
Adiabatic cooling occurs when air rises and expands.[7] The air can rise due to convection, large-scale atmospheric motions, or ... Robert Houze (October 1997). "Stratiform Precipitation in Regions of Convection: A Meteorological Paradox?". Bulletin of the ... with thunderstorms possible if the atmosphere along the trowal is unstable enough for convection.[75] Banding within the comma ... Graupel and hail indicate convection.[43] In mid-latitudes, convective precipitation is intermittent and often associated with ...
Heat flow: conduction, convection, and radiation. *The four laws of thermodynamics. *The principles of waves and sound ...
... his experimental observation of the bifurcation cascade that leads to chaos and turbulence in Rayleigh-Bénard convection ...
An electronic cigarette is a handheld battery-powered vaporizer that simulates smoking by providing some of the behavioral aspects of smoking, including the hand-to-mouth action of smoking, but without combusting tobacco.[8] Using an e-cigarette is known as "vaping" and the user is referred to as a "vaper."[9] Instead of cigarette smoke, the user inhales an aerosol, commonly called vapor.[10] E-cigarettes typically have a heating element that atomizes a liquid solution called e-liquid.[11] E-cigarettes are automatically activated by taking a puff;[12] others turn on manually by pressing a button.[9] Some e-cigarettes look like traditional cigarettes,[13] but they come in many variations.[9] Most versions are reusable, though some are disposable.[14] There are first-generation,[15] second-generation,[16] third-generation,[17] and fourth-generation devices.[18] E-liquids usually contain propylene glycol, glycerin, nicotine, flavorings, additives, and differing amounts of contaminants.[19] ...
out of fluid element(convection), div. ⁡. (. Γ. grad. ⁡. ϕ. ). {\displaystyle \operatorname {div} (\Gamma \operatorname {grad ...
Many systems can show behaviors of spontaneous time translation symmetry breaking: convection cells, oscillating chemical ... which is not the case of convection cells, oscillating chemical reactions and aerodynamic flutter), ...
Convection. *Convective available potential energy (CAPE). *Convective inhibition (CIN). *Convective instability. *Convective ...
Convection-diffusion equation. *Finite volume method, Cheng Long. *Finite volume method, Robert Eymard et al. (2010), ...
Because the space environment is essentially a vacuum, heat cannot be lost through heat convection, and can only be directly ... is used to remove body heat from the wearer in environments where evaporative cooling from sweating and open-air convection ...
Solve Heat equation with convection and diffusion from moving ball. Mesh is adaptive and recomputed at every 5th step.. ...
A lava lamp contains two immiscible liquids (a molten wax and a watery solution) which add movement due to convection. In ... liquids with low kinematic viscosity tend to transfer heat through convection at a fairly constant temperature, making a liquid ...
Hardwoods are made up mostly of three materials: cellulose, hemicellulose, and lignin. Cellulose and hemicellulose are the basic structural material of the wood cells; lignin acts as a kind of cell-bonding glue. Some softwoods, especially pines and firs, hold significant quantities of resin, which produces a harsh-tasting soot when burned; these woods are not often used for smoking. Cellulose and hemicellulose are aggregate sugar molecules; when burnt, they effectively caramelize, producing carbonyls, which provide most of the color components and sweet, flowery, and fruity aromas. Lignin, a highly complex arrangement of interlocked phenolic molecules, also produces a number of distinctive aromatic elements when burnt, including smoky, spicy, and pungent compounds such as guaiacol, phenol, and syringol, and sweeter scents such as the vanilla-scented vanillin and clove-like isoeugenol. Guaiacol is the phenolic compound most responsible for the "smoky" taste, while syringol is the primary ...
This is the process of convection. Convection comes to equilibrium when a parcel of air at a given altitude has the same ... The temperature profile of the atmosphere is a result of an interaction between radiation and convection. Sunlight in the ... The presence of water in the atmosphere complicates the process of convection. Water vapor contains latent heat of vaporization ...
If such rock rises during the convection of solid mantle, it will cool slightly as it expands in an adiabatic process, but the ...
... with help of convection or agitation. ...
The waves that pass south of this line carry moisture and create convection that leads to rain clouds.[8] Nigeria's northern ... and begins to retreat coupled with the rising of air in form of convection within this airmass (Tropical continental airmass ( ... to retreat northwards to the Sahara Desert due to massive heating of the land which transfers heat in the form of convection ...
After passing Bermuda, Nicole developed an area of convection near the center,[85] suggesting the beginning of a transition to ... The frontal zone that spawned Hurricane Gaston developed an area of convection south of Bermuda on August 25. After detaching ... Late on November 29, Otto attained its maximum sustained wind speed of 50 mph (85 km/h). Deep convection formed near the center ... A tropical wave accompanied with a well-organized area of convection emerged off the western coast of Africa on August 29. ...
cooling ponds, man-made bodies of water designed for cooling by evaporation, convection, and radiation ...
... the drop has cooled to a point where the rate of heat carried away in evaporation is equal to the heat gain through convection ...
This implies that the dynamo is missing because of a lack of convection in Venus's core. On Earth, convection occurs in the ... A dynamo requires three things: a conducting liquid, rotation, and convection. The core is thought to be electrically ...
... cut off radiation convection heat, better resistance to cold, below zero 40 ℃ still work. ...
Furnace is placed on the right and convection tube bank is on the left, super heater is arranged at .. ...
The heater has four heating areas: furnace radiation heating area, the first convection tube bundle heating area, the second ... where heat transfer takes place by convection. The flue gas gradually cools down here and flows to the front door, where it is ... The high temperature flue gas gathers at the back door and then turns to the convection tubes section (second pass), ...
Industrial Microwave Convection Oven * Belt Filter Press for Sludge Drying Machine * Oil and Beverage Machinery ...
The heat is transmitted to the inside through the surface of the food through conduction, convection or.... ...
Industrial Microwave Convection Oven * Belt Filter Press for Sludge Drying Machine * Oil and Beverage Machinery ...
Industrial Microwave Convection Oven * Nut Microwave Roasting Machine * Frozen Meat Microwave Thawing Machine ...
But Tropopause elevation is a dynamic factor in such a storm as the deep convection cloud-tops over such a large area, can lift ... It is very important to prove that all the latent heat that is released from condensation is conveyed by convection to the ... One of the implications of this theory is that oceanic heat is converted into the kenetic energy of convection and advection by ... However, wxsat imagery did show the evaporation/loss of deep convection as it was wrapping around the core. This works against ...
Isotherm® Forced Convection Laboratory Ovens. *Laboratory Incubators*Isotherm® Forced Convection Laboratory Incubators ...
Earths Heat-Conduction and Convection. We reverse the direction of the previous lecture to see how heat flows from the center ... The seafloor shows a tremendous diversity of features that are related to plate tectonics and the process of mantle convection ... Continents move because they are the surface expression of mantle convection. Two main forces are directly responsible for ... mantle convection, erosion, and even stream and lake formation. x ...
Jemiko, yes, you can use a convection oven. You may need to turn the heat down by about 25 degrees. ...
The AGW conjecture ignores the fact that heat energy transport by conduction, convection, and H2O phase change dominate over ...
... airflow occurs on enlargement movement or convection. In lieu of the chlorine that is added is allowed to breed the stronger ...
When an object travels faster than the speed of sound in a medium, a cone shaped region of high pressure called a shock wave trails behind it.
Convection, in turn, drives plate tectonics and all the accompanying dynamics of geology seen from the surface -- continents ... about the crucial role that decaying elements such as uranium and thorium play in heating up the Earth and causing convection ...
convection. heat transfer through direct contact of a circulating medium with material of a different temperature. ... a dry heating agent that transfers heat by convection. it consists of a cabinet containing finely ground particles of cellulose ...
"Eulerian-Eulerian two-phase numerical simulation of nanofluid laminar forced convection in a microchannel".. International ...
... it is relating to set a power convection on other techniques without truncating differential and sure quantities. as, a mid- ...
Iwasaka, M., Mizukawa, Y. 2015 Effect of intense magnetic fields on the convection of biogenic guanine crystals in aqueous ...
Parallel iterative methods for dynamic medical image filtering with strongly non-linear EDP models for convection-diffusion ...
... thus cooling the disk and blade by the process of convection. This method of cooling may become more difficult, as high Mach ... thus cooling the disk and blade by the process of convection. 5. Multistage turbines are used where _______ would necessitate a ...
Unsteady Double Diffusive Convection In A Laterally Heated Stable Stratified Fluid.. Author(s): D. Akrour, R. Bennacer, M. ...
hese compact loggers feature built-in sensors to reliably record temperature and relative humidity in indoor environments. The loggers can be used... (89356)
Liquid Flow Forced Convection in Rectangular Microchannels With Nonuniform Heating: Toward Analytical Modeling of Hotspots J. ...
To compare anelastic and compressible convection-permitting weather forecasts for the Alpine region - Modeling the prediction ...
  • In this article, a numerical study was conducted to analyze the effect of electro-convection and electro-thermo-convection in a solar chimney geometry subjected to the simultaneous action of an electric field and a thermal gradient (in the case of electro-thermo-convection). (iieta.org)
  • While recent work with this approach has mainly addressed the model classes where the resulting LCPs are highly structured and can be solved fairly easily, this paper discusses a variety of option pricing models that are formulated as partial differential complementarity problems (PDCPs) of the convection-diffusion kind whose numerical solution depends on a better understanding of LCP methods. (cornell.edu)
  • Tropical tropospheric ozone is mainly affected by lightning NO x and convection in the upper troposphere and by surface emissions in the lower troposphere. (atmos-chem-phys.net)
  • Role of convection in redistributing formaldehyde to the upper troposphere over. (nasa.gov)
  • Measurements of formaldehyde (CH2O) from a tunable diode laser absorption spectrometer (TDLAS) were acquired onboard the NASA DC-8 aircraft during the summer 2004 INTEX-NA campaign to test our understanding of convection and CH2O production mechanisms in the upper troposphere (UT, 6-12 km) over continental North America and the North Atlantic Ocean. (nasa.gov)
  • Currently, he is working in cooperation with researchers of the Solar Energy Laboratory (LES) at UFPB on application of the Generalized Integral Transform Technique (GITT) in magnetohydrodynamic problems, as well as in conduction-convection-radiation coupling problems. (e-papers.com.br)
  • We reverse the direction of the previous lecture to see how heat flows from the center of Earth toward the surface, exploring the phenomena of heat radiation, conduction, and convection. (thegreatcourses.com)