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The current study aimed to identity the optimal low-cost stroller cooling strategies for use in hot and moderately humid summer weather. A commercially available stroller was instrumented to assess the key parameters of the thermal environment. The cooling efficacy of eight different stroller configurations was examined in a counterbalanced order across 16 hot summer days (air temperature (Ta) = 33.3 ± 4.1 °C; relative humidity = 36.7 ± 15%; black globe temperature = 43.9 ± 4.6 °C). Compared with a standard-practice stroller configuration, combining a moist muslin draping with a battery-operated clip-on fan provided optimal in-stroller cooling, reducing the end-trial air temperature by 4.7 °C and the wet bulb globe temperature (WBGT) by 1.4 °C. In contrast, in-stroller temperatures were substantially increased by draping a dry muslin (Ta = +2.6 °C; WBGT = +0.9 °C) or flannelette (Ta = +3.7 °C; WBGT = +1.4 °C) cloth over the stroller carriage. These findings provide empirical evidence which may inform guidance aimed at protecting infants during hot weather. Practitioner summary: This study examined the efficacy of traditional and novel stroller cooling strategies for use in hot and moderately humid weather. Covering the carriage with a dry muslin cloth substantially increased stroller temperatures and should be avoided. Evaporative cooling methods reduced in-stroller temperatures. A moist muslin cloth draping combined with a fan provided optimal stroller cooling. [ABSTRACT FROM AUTHOR]

In the current energy scenario, gas turbine combined cycles (GTCCs) are considered key drivers for the transition towards fossil-free energy production. However, to meet this goal, they must be able to cope with rapid changes in power request and extend their operating range beyond the limits imposed by the environmental conditions in which they operate. The European H2020 project PUMP-HEAT (Pump-Heat Project, 2021, D4. 6 - "Validation Results in Energy -Hub of MPC With Cold Thermal Storage,") aims at achieving this goal thanks to the integration of the GTCC with a heat pump (HP) and a thermal energy storage (TES). To study this setup, a dedicated cyber-physical facility was built at the University of Genova laboratories, Italy. The plant includes physical hardware, such as a 100kWel microgas turbine, (mGT), a 10 kWel HP and a 180 kWh change phase material-based TES. These real devices are up-scaled thanks to performance maps and real-time dynamic models to emulate a full-scale heavy-duty 400 MW GTCC with a cyber-physical approach. The control system determines the optimal configuration of the whole plant and the operative point of the real devices to minimize the mismatch with a real electric power demand curve. Different operative configurations are tested: one for reducing the power production of the plant below the minimum environmental load (MEL) and two for augmenting the plant maximum power under certain ambient conditions. From the analysis of these tests, it is possible to verify the effectiveness of the proposed concept and characterize the transient behavior of the real components. [ABSTRACT FROM AUTHOR]

This study compared neuromechanical characteristics of voluntary (maximum voluntary contraction (MVC) peak torque, rate of torque development (RTD), voluntary activation (VA)) and electrically stimulated contractions (peak torque, RTD) when performed under the same temperature conditions. Twelve physically active males performed two isometric MVCs of the quadriceps muscle group in an isokinetic dynamometer. The MVCs were performed after lower limb submersion for 20 min in hot (40°C) or cold (10°C) water. A control MVC was performed in ambient room temperature (17 ± 0.7°C). Electrical twitches were delivered at rest pre-MVC (Unpotentiated), during the plateau phase of the MVC (Superimposed) and post-MVC (Potentiated). Peak torque for MVC, Unpotentiated and Potentiated was recorded. RTD was calculated for the MVC (at 50, 100, 150, 200 ms and peak torque time points), Unpotentiated and Potentiated twitches, while VA (using the central activation ratio method) was calculated. There was no significant change between conditions in MVC peak torque, MVC RTD, VA and (averaged) twitch peak torque (p > 0.05). Twitch RTD for the hot condition (1025.0 ± 163.0 N·m·s−1) was significantly higher (p = 0.003) than control (872.3 ± 142.9 N·m·s−1). In conclusion, environmental temperature changes, in the range examined, do not affect the ability to generate maximum torque or any of the RTD parameters in maximum voluntary isometric contractions. In contrast, increased heat results in higher RTD in electrically stimulated contractions, most likely induced by reduced contraction time. This has practical implications for the use of electromyostimulation for injury prevention. [ABSTRACT FROM AUTHOR]

Heat dissipation has become a key issue in electronic devices with high integration and miniaturization. As an effective way of heat transfer, radiative cooling has aroused a great attention in these devices. However, heat dissipation based on radiative cooling coating is limited by the poor heat spreading and temperature nonuniformity. Herein, a synergic augment strategy of excellent thermal conduction and strong thermal emission is proposed to improve the heat dissipation and temperature uniformity of radiative cooling coating. By the strategy, a composite coating consisting of poly(vinylidene fluoride‐co‐hexafluoropropene) and graphite is designed. It is shown via experiment that heat dissipation in composite coating is enhanced by 7% during daytime. A large temperature reduction of about 15.5 °C is obtained at the surface of the heat source with a composite coating during daytime. The temperature difference of the surface for composite coating within 2 °C demonstrates that the temperature uniformity of radiative cooling coating is improved. [ABSTRACT FROM AUTHOR]

Possibilities of increasing the efficiency of technology for production of 8–16 (25) mm thick strip in strip mills having different consumer demand for hot-rolled sheet are demonstrated. Such production methods as redistribution of reductions in the roughing group stands, installation of induced cooling and heat protection screens on the intermediate roller table, rolling sheet of variable thickness ("wedgeshaped") in the finishing group of stands, make it possible to control temperature effectively both over strip length and thickness without use of external heat sources, and without loss of continuous hot rolling high productivity. [ABSTRACT FROM AUTHOR]

This paper deals with the numerical study of the combined heat and mass exchanges in the process of direct evaporative cooler, from a porous media of laminar air flow between two parallel insulated walls. The numerical model implements momentum, energy, and mass conservation equations of humid air and water flow incorporating non-Darcian model in the porous region. The finite volume method is used for the mathematical model resolution, and the velocity-pressure coupling is treated with the SIMPLE algorithm. The main objective of this study is to examine the influences of ambient conditions and the porous medium properties (porosity and porous layer thickness) on the direct evaporative cooling performance from a porous layer. The major results of this study demonstrate that the porous evaporative wall could, in a satisfying manner, reduce the bulk air temperature. The better cooling performance can be achieved for lower air mass flow at the entrance and relative humidity. Additionally, the evaporative cooler is more effective for a high porosity and a thick porous medium, with an improvement achieving 23% for high porosity. [ABSTRACT FROM AUTHOR]

The main objective of this study is to identify how climate variability and urbanization influence human comfort levels in tropical-coastal urban environments. San Juan Metro Metropolitan Area (SJMA) of the island of Puerto Rico was chosen as a reference point. A new human discomfort index (HDI) based on environmental enthalpy is defined to determine the energy required to maintain indoor human comfort levels. Regression analysis shows that both temperature and HDI are good indictors to predict total electrical energy consumption. Results showed that over the past 35 years, the average environmental enthalpy have increased, resulting in the increase of average HDI with clear bias due to urbanization. Local scale weather station data show a decreasing rate of maximum cooling per capita at -11.41 kW h/years and increasing of minimum cooling per capita of 10.64 kW h/years; however, for the whole Caribbean region, an increasing trend is observed for both minimum and maximum cooling per capita. To estimate human comfort levels under extreme heat wave events conditions, an event of 2014 was identified. The analysis is complemented by simulations from the weather forecasting system (WRF) at a resolution of 1 km, forced by data from the National Center for Environmental Prediction at 250 km spatial resolution. WRF model results were evaluated against observations showing good agreement for both temperature and relative humidity (RH) and improvements. It also shows that energy per capita in urban areas during a heat wave event can increase to 21% as compared to normal day. [ABSTRACT FROM AUTHOR]

This paper presents a three-dimensional electrothermal numerical model of the medium voltage outdoor circuit breaker. The model was validated by heat run test performed under the conditions required by IEC 62271-1 and IEC 62271-100 standards, as well as some other specific requirements related to the breaker overload under low ambient temperature conditions and natural cooling. The purpose of this study was to build a numerical model of the medium-voltage circuit breaker that could be successfully applied for the redesign of the breaker for more demanding operating conditions with minimum physical test iterations. The numerical results obtained were found to be in a good agreement with experimental values having the average discrepancy of 3 K with the maximum below 5 K on busbars. [ABSTRACT FROM AUTHOR]

Purpose: Cooling sensations elicited by mouth rinsing with L-menthol have been reported as ergogenic. Presently, responses to L-menthol mouth rinsing during intermittent sprint performance (ISP) in the heat are unknown and the impact of increased thermal perception on ISP via capsaicin has also not been quantified. This experiment aimed to identify whether eliciting cooling/warming sensations via L-menthol/capsaicin would alter ISP in the heat.Method: Fourteen participants (mass = 72 ± 9 kg, [Formula: see text] = 3.30 ± 0.90 L min-1), undertook four experimental trials, involving 40 min of ISP in hot conditions (40.2 ± 0.6 °C, 42 ± 2% R.H.) with mouth rinsing (25 mL, 6 s) at the protocol onset, and every 10 min thereafter. Cooling (0.01% L-menthol; MEN), warming (0.2% capsaicin; CAP), placebo (0.3 sham-CHO; PLA), and control (water; CON) mouth rinses were utilized. Performance was quantified via power (PP) and work done (WD) during sprints. Heart rate (HR), core (Trec) and skin (Tskin) temperature, perceived exertion (RPE), thermal sensation (Tsens), and comfort (Tcom) were measured at 10 min intervals. Sweat rate (whole-body sweat rate) was calculated from ∆mass.Result: PP reduced over time (P < 0.05); however, no change was observed between trials for PP or WD (P > 0.05). Tcom increased over time and was lower in MEN (2.7 ± 1.1; P < 0.05) with no difference between CAP (3.1 ± 1.2), PLA (3.2 ± 1.3) and CON (3.1 ± 1.3). RPE, Tsens HR, Trec, and Tskin increased over time (P < 0.05) with no between trial differences (P > 0.05).Conclusion: Despite improved thermal comfort via L-menthol, ISP did not improve. Capsaicin did not alter thermal perception or ISP. The reduction in ISP over time in hot conditions is not influenced by thermal perception. [ABSTRACT FROM AUTHOR]

A building energy simulation study is carried out to analyze the performance of a triple-hybrid single-effect vapor absorption cooling system (VACS) operated by solar, natural gas, and auxiliary electricity-based cogeneration. A high capacity small office building subjected to different climatic conditions is considered. The system is designed to continuously maintain a specified building comfort level throughout the year under diverse environmental conditions. Simulations are done at different generator temperatures to investigate the performance in terms of total annual electric energy consumption, heating energy, and the coefficient of performance (COP). The performance of the present VACS is compared with the conventional compression-based system, which demonstrates the electric energy and cost saving potentials of the proposed VACS. Simulation outcomes are well-validated against benchmark data from national renewable energy laboratory and energy conservation building code. Interestingly, it is found that beyond a certain collector area, surplus energy savings can be acquired with the present triple-hybrid VACS as compared to the compression-based cooling. Results also show that COP of the simulated system is in line with experimental values available in the literature. Finally, recommendations are given to operate the complete system on solar and biomass resources, which provide encouraging opportunity for agriculture-based countries. [ABSTRACT FROM AUTHOR]

Load-carrying capacity of weld joints could be identified by its shape and size where weld bead geometry and shape relationship parameters are of utmost importance. Heat input and preheating temperature together can control the cooling time of weld, which in turn determines the weld microstructure and its mechanical properties. To control the shape and geometry of weld bead, it is necessary to understand its relationship with cooling time. In present work, preheating temperature is used as process variable along with heat input varying parameters for understanding their effects on weld bead geometry and shape relationship parameters using submerged arc welding process on high-strength low alloy pipeline steel. The experimental investigation was then analyzed by using the mathematical modeling in context with response surface methodology. The mathematical model predicts the influential dependency of cooling time on the preheating temperature than the other weld process parameters. The associated effects in relation to the process parameters have been discussed and analyzed in the present study. [ABSTRACT FROM AUTHOR]

Highlights • A new coupled cooling method implementing a phase change chair (PCC) was proposed. • Simplified numerical models of PCC and coupled cooling system were established. • The indoor temperature could reduce by 4 °C in contrast to the case without PCC. • Conditions of achieving the optimal thermal control effects were proposed. Abstract A latent heat thermal energy storage system is a safe, stable, and reliable method of controlling the room temperature. However, this system is difficult to fit in some harsh environments such as a mine refuge chamber where the temperature is high. In this article, a new coupled cooling method implementing a phase change chair (PCC) is proposed, which is not only suitable for harsh environments, but also saves valuable living space. A new PCC model and a simplified coupled heat transfer model considering the air, surrounding rock, PCC, and heat source are established. The effects of melting temperature, latent heat, thermal conductivity, and thickness of PCC were systematically investigated. The analysis results indicated that: (i) the coupled cooling method based on the PCC could effectively control the temperature in 40 h. (ii) under the given operating conditions, the optimal melting temperature is approximately 27 °C, and the thermal conductivity of PCC is 0.6 W/m K. (iii) increasing the latent heat and the thickness of PCC has a similar effect on temperature control. For every 30 kJ/kg increase in the latent heat or 0.01 m increase in the thickness, the control time increases by 4.5 h, but the effect gradually decreases. [ABSTRACT FROM AUTHOR]

This paper focuses on the thermal and energetic behavior of a building located in the Brazilian Amazon Region, a region climatically characterized by elevated temperatures and high humidity levels, where achieving adequate thermal comfort demands a high-energy consumption due to the use of air-conditioning systems. Therefore, different energy conservation measures (ECMs) need to be evaluated to reduce the thermal load for cooling. The use of a thermal insulation material on the west wall and on the roof, and a photovoltaic (PV) system integrated as an architectural element and adapted to the roof of the building are considered. The building is simulated with the software energyplus, with its thermal behavior and energy consumption analyzed for an entire year and for a chosen design day, defined with data measured by a weather station installed close to the building. According to the evaluations carried out, it is determined that the ECMs have a direct and major influence on the reduction of the thermal load for cooling, on the reduction of the effects caused by radiation with the shading on the eaves, and the reduction of the transmittance on the surfaces that were modified in the study. In terms of energy consumption and economic feasibility, the ECMs reach an annual energy saving percentage of 74% for the building chosen as the case study, and the solutions adopted provide the return of the financial investment, proving suitable for energy saving and economically viable for regions with similar climatic characteristics. [ABSTRACT FROM AUTHOR]

Laser engineering net shaping (LENS) is one of the representative processes of directed energy deposition (DED) in which a moving heat source having high-intensity melts and fuses metal powders together to print parts. The complex and nonuniform thermal gradients during the laser heating and cooling cycles in the LENS process directly affect the microstructural characteristics, and thereby the ultimate mechanical properties of fabricated parts. Therefore, prediction of microstructure evolution during the LENS process is of paramount importance. The objective of this study is to present a thermo-microstructural model for predicting microstructure evolution during the LENS process of Ti-6Al-4V. First, a detailed transient thermal finite element (FE) model is developed and validated for a sample LENS process. Then, a density type microstructural model which enables calculation of the α-phase fractions (i.e., Widmanstätten colony and basketweave α-phase fractions), β-phase fraction, and alpha lath widths during LENS process is developed and coupled to the thermal model. The microstructural algorithm is first verified by comparing the phase fraction results with the results presented in the literature for a given thermal history data. Second, the average lath width values calculated using the model are compared with the experimentally measured counterparts, where a reasonable agreement is achieved in both cases. [ABSTRACT FROM AUTHOR]

The effect of nanoparticle coating on the performance of a miniature loop heat pipe (mLHP) is experimentally investigated for heat inputs of 20'380 W using distilled water as the working fluid. Applications include the cooling of electronic devices such as circuit breaker in low voltage switch board and insulated gate bipolar transistor. Physical vapor deposition method is used to coat the nanoparticles on the evaporator surface for different coating thicknesses of 100 nm, 200 nm, 300 nm, 400 nm, and 500 nm, respectively. An optimum filling ratio (FR) of 30% is chosen for the analysis. Experimental findings show that the nanoparticle coating gives a remarkable improvement in heat transfer of the heat pipe. An average reduction of 6.7%, 11.9%, 17.2%, and 22.6% in thermal resistance is observed with coating thicknesses of 100 nm, 200 nm, 300 nm, and 400 nm, respectively. Similarly, enhancements in evaporator heat transfer coefficients of 47%, 63.5%, 73.5%, and 86% are noted for the same coating thicknesses, respectively. Evaporator wall temperature decreased by 15.4 °C for 380 W with a coating thickness of 400 nm. The repeatability test ensures the repeatability of experiments and the stability of coatings in the long run. [ABSTRACT FROM AUTHOR]

Presented here are the results of an experimental investigation of two ultrathin miniature loop heat pipes (mLHPs) with different internal wicking structures: one with a primary wicking structure in the evaporator and a secondary wicking structure in the liquid line, and the other only with the same primary wicking structure in the evaporator, but no secondary wick. The systematic experimental investigation was conducted using natural convection as the cooling mechanism in order to study the heat transfer performance of the two mLHPs and fully examine the effects of the secondary wick. The results indicated that both of the test articles could effectively dissipate 12 W at all test orientations with a minimum total thermal resistances of 6.38 °C/W and 6.39 °C/W, respectively. However, the results indicated that the presence of the secondary wicking structure in the liquid line at low power loads resulted in more stable startup characteristics and a weaker dependence on the different orientations. Moreover, it was demonstrated that the steady-state evaporator temperatures of the test article with the secondary wicking structure in the liquid line were much lower than those observed for a 1-mm thick copper plate with the same geometric dimensions for all heat loads in the horizontal orientation, showing a higher thermal performance. [ABSTRACT FROM AUTHOR]

Most of the microstructural changes in weldment takes place during weld cooling from 800 °C to 500 °C (t8/5) specially in the heat-affected zone (HAZ). Weld strength and cracking tendency can also relate to t8/5. A generalized model using dimensional analysis has been proposed for estimation of the weld cooling time (t8/5) for variable plate thicknesses. The proposed model is based on rotatable central composite designed submerged arc welding (SAW) experiments. The model considers material properties, weld parameters, and environmental conditions for submerged arc welding. The model is validated with experimental data and cooling time observed by other researchers. The adequacy of the model was found to be 97% and able to predict cooling time for a plate thickness ranging from 8 to 41.5 mm thickness. [ABSTRACT FROM AUTHOR]

Compared with traditional speed regulation (SR) approaches like variable frequency and hydraulic coupling, magnetorheological clutch (MRC) provides a more superior solution for high-efficiency energy saving SR. However, recent developments have demonstrated that severe heating is an outstanding challenge for MRC, especially in high-power applications. Among commonly used cooling methods, liquid cooling offers a viable alternative for the problem. Aiming at pre-evaluating the cooling efficiency of a liquid-cooled MRC in high-power situations, this study introduces a heat-flow coupling simulation method. In this paper, theoretical basis for the simulation is presented first, which is followed by an illustration of the heat-flow coupling simulation. This paper details the simulation model establishment, finite element meshing (FEM), boundary conditions, and simulation parameters. After the simulations, the results concerning the steady flow field of the internal coolant, along with the steady-state temperature fields of MRC, magnetorheological (MR) fluids and the coolant are presented and discussed. Finally, several heating tests of an MRC prototype under various operation conditions are performed and the results verify the correctness and rationality of the simulation. [ABSTRACT FROM AUTHOR]

The development of newer and more efficient cooling techniques to sustain the increasing power density of high-performance computing systems is becoming one of the major challenges in the development of microelectronics. In this framework, two-phase cooling is a promising solution for dissipating the greater amount of generated heat. In the present study, an experimental investigation of two-phase flow boiling in a micro-pin fin evaporator is performed. The micro-evaporator has a heated area of 1 cm2 containing 66 rows of cylindrical in-line micro-pin fins with diameter, height, and pitch of, respectively, 50 μm, 100 μm, and 91.7 μm. The working fluid is R1234ze(E) tested over a wide range of conditions: mass fluxes varying from 750 kg/m2 s to 1750 kg/m2 s and heat fluxes ranging from 20 W/cm2 to 44 W/cm2. The effects of saturation temperature on the heat transfer are investigated by testing three different outlet saturation temperatures: 25 °C, 30 °C, and 35 °C. In order to assess the thermal-hydraulic performance of the current heat sink, the total pressure drops are directly measured, while local values of heat transfer coefficient are evaluated by coupling high-speed flow visualization with infrared temperature measurements. According to the experimental results, the mass flux has the most significant impact on the heat transfer coefficient while heat flux is a less influential parameter. The vapor quality varies in a range between 0 and 0.45. The heat transfer coefficient in the subcooled region reaches a maximum value of about 12 kW/m2 K, whilst in two-phase flow it goes up to 30 kW/m2 K. [ABSTRACT FROM AUTHOR]

The performance of a novel impinging two-phase jet heat sink operating with single and multiple jets is presented and the influence of the following parameters is quantified: (i) thermal load applied on the heat sink and (ii) geometrical arrangement of the orifices (jets). The heat sink is part of a vapor compression cooling system equipped with an R-134a small-scale oil-free linear motor compressor. The evaporator and the expansion device are integrated into a single cooling unit. The expansion device can be a single orifice or an array of orifices responsible for the generation of two-phase jet(s) impinging on a surface where a concentrated heat load is applied. The analysis is based on the thermodynamic performance and steady-state heat transfer parameters associated with the impinging jet(s) for single and multiple orifice tests. The two-phase jet heat sink was capable of dissipating cooling loads of up to 160 W and 200 W from a 6.36 cm² surface for single and multiple orifice configurations, respectively. For these cases, the temperature of the impingement surface was kept below 40 °C and the average heat transfer coefficient reached values between 14,000 and 16,000 W/(m² K). [ABSTRACT FROM AUTHOR]

Heat transfer effects play a significant role in assessing the performance of automotive turbochargers. Thermal effects are becoming increasingly relevant due to reduced machine sizes and increased exhaust gas temperatures. In this work, a study of the individual energy flows is conducted by simulation of a complete turbocharger comprising compressor (dC=51mm), turbine, and bearing housing using conjugate heat transfer. Special focus is given to the analysis of the various heat flows occurring in the machine aiming to identify the major heat transfer paths and their sensitivity with respect to varying operating conditions. Cooling of the bearing housing is shown to be a powerful thermal isolator mitigating the heat transferred to the compressor by up to 60%. Moreover, the rotating speed largely dictates the amount of heat transfer in the compressor and the direction of the heat flow: Whereas at low speeds (22% of max. speed), 117W are introduced into the fluid and 338 W are being discharged from the fluid at maximum speed. At high speed operation, the heat transfer is shown to be insignificant compared to the aerodynamic work. At low speeds, however, it can reach up to 35% of the aerodynamic work. While the turbine inlet temperature largely governs the overall heat that is lost from the exhaust gas passing the turbine (from 630W at 300°C up to 3.72kW at 1050°C), only a minor effect on the compressor heat transfer is detected. [ABSTRACT FROM AUTHOR]

In order to reach the targets on emissions set by the European Commission, both new and existing buildings must reduce their fossil fuel inputs. Solar thermal cooling supplying on-site renewable heating and cooling could potentially contribute toward this goal. In this paper, a novel concept for solar thermal cooling providing efficient coproduction of cooling and heating based on sorption integrated vacuum tube collectors is proposed. A prototype collector has been constructed and tested in a solar laboratory based on a method developed specifically for sorption integrated collectors. From the test results, the key performance parameters have been determined and used to calibrate a mathematical model for trnsys environment. System simulation has been conducted to optimize the collector and sorption module configuration by performing a parametric study where different vacuum tube center-center (C-C) distances and sorption module designs are tested for a generic hotel in Ankara, Turkey. The parametric study showed that the heating and cooling output per year can be as high as 1000 kWh/m2 for solar fractions above 50%, and that the output per sorption module compared to the prototype can more than double with an optimized design. Furthermore, cooling conversion efficiencies defined as total cooling output per total solar insolation can be as high as 26% while simultaneously converting 35-40% of the incident solar energy into useful hot water. [ABSTRACT FROM AUTHOR]

Major new metropolitan centers experience challenges during management of peak electrical loads, typically occurring during extreme summer events. These peak loads expose the reliability of the electrical grid on the production and transmission side, while customers may incur considerable charges from increased metered peak demand, failing to meet demand response program obligations, or both. These challenges create a need for analytical tools that can inform building managers and utilities about near future conditions so they are better able to avoid peak demand charges and reduce building operational costs. In this article, we report on a tool and methodology to forecast peak loads at the city scale using New York City (NYC) as a test case. The city of New York experiences peak electric demand loads that reach up to 11GW during the summertime, and are projected to increase to over 12GW by 2025, as reported by the New York Independent System Operator (NYISO). The energy forecast is based on the Weather Research and Forecast (WRF) model version 3.5, coupled with a multilayer building energy model (BEM). Urban morphology parameters are assimilated from the New York Primary Land Use Tax-Lot Output (PLUTO), while the weather component of the model is initialized daily from the North American Mesoscale (NAM) model. A city-scale analysis is centered in the summer months of June-July 2015 which included an extreme heat event (i.e., heat wave). The 24-h city-scale weather and energy forecasts show good agreement with the archived data from both weather stations records and energy records by NYISO. This work also presents an exploration of space cooling savings from the use of white roofs as an application of the city-scale energy demand model. [ABSTRACT FROM AUTHOR]

Context: The National Athletic Trainers' Association and the American College of Sports Medicine have recommended removing American football uniforms from athletes with exertional heat stroke before cold-water immersion (CWI) based on the assumption that the uniform impedes rectal temperature (Trec) cooling. Few experimental data exist to verify or disprove this assumption and the recommendations. Objectives: To compare CWI durations, Trec cooling rates, thermal sensation, intensity of environmental symptoms, and onset of shivering when hyperthermic participants wore football uniforms during CWI or removed the uniforms immediately before CWI. Design: Crossover study. Setting: Laboratory. Patients or Other Participants: Eighteen hydrated, physically active men (age = 22 ± 2 years, height=182.5 ± 6.1 cm, mass = 85.4 ± 13.4 kg, body fat = 11% ± 5%, body surface area = 2.1 ± 0.2 m²) volunteered. Intervention(s): On 2 days, participants exercised in the heat (approximately 40°C, approximately 40% relative humidity) while wearing a full American football uniform (shoes; crew socks; undergarments; shorts; game pants; undershirt; shoulder pads; jersey; helmet; and padding over the thighs, knees, hips, and tailbone [PADS]) until Trec reached 39.5°C. Next, participants immersed themselves in water that was approximately 10°C while wearing either undergarments, shorts, and crew socks (NOpads) or PADS without shoes until Trec reached 38°C. Main Outcome Measure(s): The CWI duration (minutes) and Trec cooling rates (°C/min). Results: Participants had similar exercise times (NOpads = 40.8 ± 4.9 minutes, PADS = 43.2 ± 4.1 minutes; t17 = 2.0, P = .10), hypohydration levels (NOpads = 1.5% ± 0.3%, PADS = 1.6% ± 0.4%; t17 = 1.3, P = .22), and thermal-sensation ratings (NOpads = 7.2 ± 0.3, PADS = 7.1 ± 0.5; P > .05) before CWI. The CWI duration (median [interquartile range]; NOpads = 6.0 [5.4] minutes, PADS = 7.3 [9.8] minutes; z = 2.3, P = .01) and Trec cooling rates (NOpads = 0.28°C/min ± 0.14°C/min, PADS = 0.21°C/min ±0.11°C/min; t17 = 2.2, P = .02) differed between uniform conditions. Conclusions: Whereas participants cooled faster in NOpads, we still considered the PADS cooling rate to be acceptable (ie, .0.16°C/min). Therefore, if clinicians experience difficulty removing PADS or CWI treatment is delayed, they may immerse fully equipped hyperthermic football players in CWI and maintain acceptable Trec cooling rates. Otherwise, PADS should be removed preimmersion to ensure faster body core temperature cooling.) cooling. Few experimental data exist to verify or disprove this assumption and the recommendations. Objectives: To compare CWI durations, Trec cooling rates, thermal sensation, intensity of environmental symptoms, and onset of shivering when hyperthermic participants wore football uniforms during CWI or removed the uniforms immediately before CWI. Design: Crossover study. Setting: Laboratory. Patients or Other Participants: Eighteen hydrated, physically active men (age = 22 ± 2 years, height=182.5 ± 6.1 cm, mass = 85.4 ± 13.4 kg, body fat = 11% ± 5%, body surface area = 2.1 ± 0.2 m²) volunteered. Intervention(s): On 2 days, participants exercised in the heat (approximately 40°C, approximately 40% relative humidity) while wearing a full American football uniform (shoes; crew socks; undergarments; shorts; game pants; undershirt; shoulder pads; jersey; helmet; and padding over the thighs, knees, hips, and tailbone [PADS]) until Trec reached 39.5°C. Next, participants immersed themselves in water that was approximately 10°C while wearing either undergarments, shorts, and crew socks (NOpads) or PADS without shoes until Trec reached 38°C. Main Outcome Measure(s): The CWI duration (minutes) and Trec cooling rates (°C/min). Results: Participants had similar exercise times (NOpads = 40.8 ± 4.9 minutes, PADS = 43.2 ± 4.1 minutes; t17 = 2.0, P = .10), hypohydration levels (NOpads = 1.5% ± 0.3%, PADS = 1.6% ± 0.4%; t17 = 1.3, P = .22), and thermal-sensation ratings (NOpads = 7.2 ± 0.3, PADS = 7.1 ± 0.5; P > .05) before CWI. The CWI duration (median [interquartile range]; NOpads = 6.0 [5.4] minutes, PADS = 7.3 [9.8] minutes; z = 2.3, P = .01) and Trec cooling rates (NOpads = 0.28°C/min ± 0.14°C/min, PADS = 0.21°C/min ±0.11°C/min; t17 = 2.2, P = .02) differed between uniform conditions. Conclusions: Whereas participants cooled faster in NOpads, we still considered the PADS cooling rate to be acceptable (ie, .0.16°C/min). Therefore, if clinicians experience difficulty removing PADS or CWI treatment is delayed, they may immerse fully equipped hyperthermic football players in CWI and maintain acceptable Trec cooling rates. Otherwise, PADS should be removed preimmersion to ensure faster body core temperature cooling. [ABSTRACT FROM AUTHOR]

Exercising in the heat induces thermoregulatory and other physiological strain that can lead to impairments in endurance exercise capacity. The purpose of this consensus statement is to provide up-to-date recommendations to optimize performance during sporting activities undertaken in hot ambient conditions. The most important intervention one can adopt to reduce physiological strain and optimize performance is to heat acclimatize. Heat acclimatization should comprise repeated exercise-heat exposures over 1-2 weeks. In addition, athletes should initiate competition and training in a euhydrated state and minimize dehydration during exercise. Following the development of commercial cooling systems (e.g., cooling vest), athletes can implement cooling strategies to facilitate heat loss or increase heat storage capacity before training or competing in the heat. Moreover, event organizers should plan for large shaded areas, along with cooling and rehydration facilities, and schedule events in accordance with minimizing the health risks of athletes, especially in mass participation events and during the first hot days of the year. Following the recent examples of the 2008 Olympics and the 2014 FIFA World Cup, sport governing bodies should consider allowing additional (or longer) recovery periods between and during events for hydration and body cooling opportunities when competitions are held in the heat. [ABSTRACT FROM AUTHOR]

Summary Understanding the temperature dynamics of rivers is critical for their management and for ecological and biogeochemical aquatic processes. In proglacial rivers, there is typically a paucity of thermal observations which in turn limits the understanding of these sensitive and evolving environments. Here we collected ground-based thermal images, with approximately meter resolution and imaged every half hour for 24 h, of a proglacial river and 2 km 2 of its floodplain and interpret the observations using a numerical energy balance model. The images revealed the longitudinal thermal pattern of the Urbach River in Switzerland – there was gradual cooling in the upstream half of the study section and then warming in the remaining downstream portion. This pattern persisted through the diurnal warming and cooling cycle. The spatio-temporal thermal pattern was explained by a model that included distributed thermal inputs of cooler water in the upstream half coming from alluvial fans and warmer water in the downstream half running off steep cliffs that warm snowmelt. The warm inputs from the cliffs were confirmed by the thermal imaging. These data and the associated modeling illustrated that distributed inflows can overwhelm the influence of atmospheric fluxes, and that their knowledge is critical for understanding stream temperatures. The combination of modeling and detailed time-lapse thermal imaging allowed for identification and quantification of processes critical to in-stream temperature dynamics in a proglacial river. [ABSTRACT FROM AUTHOR]

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The article discusses research investigating the relationship between heat extraction from the palm, work volume, and strength training responses to resistive exercise. Topics include an overview of the study's experimental design, results of core temperature and work volume measurements, and the study's conclusion regarding the effects of palm cooling on work volume and the link between core temperature and fatigue onset during resistive exercise.

The article discusses research which was conducted to compare pulmonary artery blood temperature (via thermistor in a pulmonary artery catheter) with intestinal temperature during whole body heat stress followed by whole body cooling in healthy humans. Researchers evaluated eight subjects They found that in subjects who were subjected to heat stress and whole body cooling early temperature changes in the intestine appeared to be less than temperature changes which were seen in pulmonary artery blood.

Abstract: Design of an effective cooling system in polymer electrolyte membrane fuel cells (PEMFCs) is vital for the heat management and overall performance of stacks. Depending on the stack size and application, either air or water-cooling can be used to extract excess heat and maintain the desired temperature distribution throughout the stack. A computational model previously assembled by the authors has been used to design cooling plates for a typical air-cooled stack configuration. The aim of these designs was to minimise temperature differences between cells, and dissipate heat from the stack. Three different cooling plate designs are analysed both computationally and experimentally within stacks containing electrically heated pads in place of active MEAs. Good agreement was achieved between the model and experiment, and results showed that implementing a cooling plate is an effective way to balance temperature variation within a stack and minimise thermal issues. It was found that the temperature variation may be minimised by implementing plates with wider cooling channels. As a result, more air may be forced through the channels with less resistance, which minimises the power required by the air blower, and hence the parasitic load on the system. [Copyright &y& Elsevier]

Objectives: Endoscopic microlaryngeal laser surgery performed with general anesthesia through a laryngoscope speculum generates heat that accumulates at the distal lumen, creating an "oven" effect and potentially causing bystander thermal damage to nontarget tissue such as the contralateral vocal fold. We report the effects of cooling on air and tissue temperatures that occurred during simulated laryngeal laser surgery with KTP and thulium lasers in an ex vivo calf model. Methods: Ten fresh excised calf larynges were studied at room temperature. Laser energy was applied to one vocal fold for 2 minutes, with or without cooling, while temperatures were monitored with sensors placed within the glottal lumen or inserted superficially into the contralateral vocal fold. A pulsed KTP laser (525 mJ) was used for 5 larynges, and a thulium laser (7 W, continuous) was used for the other 5 larynges. Results: Heating was slightly greater for the KTP laser than for the thulium laser with use of these parameters. The lumen temperatures for both lasers increased an average of 13.2° C without cooling, but only 6.7° C with cooling (p < 0.05). The contralateral vocal fold (subepithelial space) temperature increased an average of 6.8° C without cooling, but only 4.2° C with cooling (p> 0.05). Conclusions: Cooling with room-temperature air during laryngeal laser surgery reduces luminal air and contralateral vocal fold temperatures. This effect is believed to be due to elimination of the plume of steam and smoke that significantly heats surrounding structures. [ABSTRACT FROM AUTHOR]

This paper presents an analysis of thermal dynamics in multicore systems, focusing on time response to heat generated in a single core and its connection with very large scale integration (VLSI) design principles. For the purpose of this paper, a point heating time (PHT) concept is introduced. PHT is a value that describes the time of temperature growth to its limited value. The PHT value is used for estimating the thermal capabilities of multicore systems. The physical properties of VLSI systems are taken into account for determining easy-to-apply rules of thermal dynamic response in common chip designs. The authors compare PHT in different physical conditions and its value versus displacement of the active thermal module away from the center position on the chip. An equation derived from analytical assumptions is the basis for asynchronous control of core activity toward minimizing its peak temperature. Final analysis leads to the conclusion that the paper can be used as a supplementary guide in VLSI chip development for better thermally optimized multicore chips. [ABSTRACT FROM PUBLISHER]

This study tested a new portable cooling device for fire fighting recovery. Participants (N = 8) walked and did arm curls (time-weighted VO2: 1.6 L· min-1 on a treadmill for 40 min in a heated chamber (wet bulb globe temperature: 33.7°C; relative humidity: 40-45%) while wearing firefighter turn-out gear and self-contained breathing apparatus (SCBA). Immediately on finishing exercise, participants recovered for 40 min with either a hand-cooling device or seated passive recovery at an ambient temperature of 22°C, 35% RH in a repeated-measures counterbalanced design. The cooling device had little impact on recovery during the first 30 min; however, compared with passive cooling, the cooling device resulted in significantly lower rectal temperature (Tre) during the last 10 min. Relative to starting Tre of the recovery period, ΔTre at 35 min had fallen 0.51 ± 0.19°C (passive) and 0.76 ± 0.30°C (active) (p = 0.03); and at 40 min ΔTre had fallen 0.63 ± 0.17°C (passive) and 0.88 ± 0.31°C (active) (p = 0.03). Cooling capacity of the device calculated from ΔTre over the whole recovery period averaged about 144% of passive. Reductions in heat storage enhance worker safety and performance in hot environments. [ABSTRACT FROM AUTHOR]

We define the characteristic temperature TC of a material by using the behaviour of the specific heat in the vicinity of this temperature: Cp,N(T ) = f(1 - (T/TC),p,N ) for T < TC and Cp,N(T ) = g((T/TC) - 1,p,N ) for T > TC where p is the external pressure and N is the number of particles. The characteristic temperature TC = TC ( p, N ) can e.g. be identified with the transition temperature in the case of continuous phase transitions or with one of the two characteristic temperatures [image omitted] (on heating) and [image omitted] (on cooling) in the case of discontinuous phase transitions. Using the idea of the characteristic temperature, we present a new method on how to calculate the Gibbs potential G = G(T, p, N) in the vicinity of the characteristic temperature, without it being a necessity to know the explicite expressions for f and g. This general and uniform approach allows to derive many thermodynamical relations connecting measurable quantities at the characterisic point as e.g. Clausius-Clapeyron equation and its analogs, valid for discontinuous phase transitions and 15 relations valid for both continuous and discontinuous phase transitions, 6 of them are new. As a special case of these latter relations, we find six relations valid for continuous phase transitions (Ehrenfest equation and its analogs). The derived relations result exclusively from the definition of the characteristic point and are independent from the underlying microscopical mechanism leading to phase transitions (as e.g. solid-liquid, liquid-vapour, magnetic, ferroelectric, structural and superconducting transitions) and therefore, they are generally valid. These relations can be very important for material science. Using some of them it is possible to predict (without performing additional experiments) whether the transition or characteristic temperature TC of a given material sample will increase or decrease under doping (injection) or applied pressure. Similar 24 thermodynamical relations can also be found with ease for systems described by the Helmholtz potential F = F(T,V, N ). [ABSTRACT FROM AUTHOR]

In this study, the feasibility of a newly developed interstitial cooling device inserted into the neck muscle and placed on the surface of the common carotid artery is evaluated. A combination of vascular model and continuum model is developed to simulate the temperature fields in both the neck and brain regions. Parametric studies are conducted to test the sensitivity of various factors on the temperature distribution. It has been shown that the length of the device, temperature of the device, and the tissue gap between the device and the blood vessel are the dominant factors that determine the effectiveness of this cooling approach. Under the current design parameters, the device is capable of inducing a temperature drop of 2.8°C along the common carotid artery and it results in a total of 90 W of heat carried away from the arterial blood. Although the degree of the cooling in the arterial blood is inversely proportional to the blood flow rate of the arteries, the total heat loss from the arterial blood does not vary significantly if the blood flow rate changes during the cooling. After the cold arterial blood is supplied to the brain hemisphere, temperature reduction in the brain tissue is almost uniform and up to 3.1°C temperature drop is achieved within 1 hour. In addition to the possible benefits of brain hypothermia for stroke or head injury patients, the device has the potential to control fever as well as to improve patients’ outcome during open neck and head surgery. [ABSTRACT FROM AUTHOR]

Recent hybrid electric vehicles (HEVs) are provided with a motor cooling structure that uses lubricatory automatic transmission fluid (ATF) in the motor to improve cooling performance, as the authors of this present paper proposed previously. We closely analyzed the heat flow in a motor that used ATF for cooling, by measuring temperature at many points in the motor and evaluating a section of the motor under operating conditions, and successfully established that ATF improves motor cooling performance. [ABSTRACT FROM AUTHOR]

Data from three micronetworks with eddy correlation data and three additional micronetworks without eddy correlation data are analyzed to study the spatial variability of surface air temperature in complex terrain. A simple similarity relationship is constructed to relate the spatial variation of air temperature along the slope to the thermal forcing and mixing. Mixing is not included in present empirical formulations of the surface air temperature distribution in complex terrain. The development of surface temperature gradients along the slope, resulting from surface heating or cooling, is bounded by a maximum (or saturated) value, where a further increase of temperature gradients is restricted by redistribution of heat by thermally driven slope circulations. Although much of the spatial variation of the surface air temperature is governed by complex three-dimensionality and surface vegetation, a relatively simple relationship is able to account for much of the diurnal and day-to-day variation of the spatial distribution of air temperature. This relationship requires information on the surface heat flux and friction velocity over a reference surface. Required generalizations of the relationship are outlined before it can be applied to an arbitrary site. [ABSTRACT FROM AUTHOR]

Abstract: During a wheel slide the frictional heat generated at the contact interface causes intense heating of the adjacent wheel material. If this material exceeds the austenitising temperature and then cools quickly enough, it can transform into martensite, which may ultimately crack and cause wheel failure. A knowledge of the distribution of the heat partitioned into the wheel and the rail and the resulting temperature fields is critical to developing designs to minimize these deleterious effects. A number of theoretical solutions have appeared in the literature to model the thermal aspects of this phenomenon. The objective of this investigation was to examine the limitations of these solutions by comparing them to the results of a finite element analysis that does not incorporate many of the simplifying assumptions on which these solutions are based. It was found that these simplified solutions can produce unrealistic results under some circumstances. [Copyright &y& Elsevier]

A simple method is developed for predicting discrete heat source temperatures on a finite convectively cooled substrate. The method is based on the principle of superposition using a single source solution for the mean or maximum contact temperature of an eccentric uniform heat source on a rectangular substrate. By means of influence coefficients, the effect of neighboring source strength and location may be assessed. It is shown that the influence coefficients represent localized thermal resistances, which must be weighted according to source strength. For a system of N heat sources, there exists N effects of source strength and position on any one heat source. This includes a self effect (source of interest) and N — 1 influence effects (neighboring sources). The method is developed for isotropic, orthotropic, and compound systems. Convection in the source plane is addressed for isotropic and orthotropic systems. Expressions are developed for both mean and centroidal temperature. [ABSTRACT FROM AUTHOR]

This paper presents a coupled method that determines the interface temperatures by filling and cooling analyses simultaneously to simulate the mold and part temperature distributions for injection molding. The mold temperature is assumed to be changing and is calculated with melt together at the filling stage instead of keeping constants as is usually done in conventional methods. The mold temperature is first determined with a 3-D finite element method by specifying the heat-flow rate at the interface between mold and part. Then the finite difference approach is employed to solve the melt thermal problem to get melt temperature distributions inside the cavity and the heat-flow rate at the interface. The under-relax scheme is used to correct the boundary condition and to resolve both mold and melt thermal problems until the solutions are convergent. This method can simulate transient and multicycle problems with more complex process conditions. The simulated results agree with experimental data. [ABSTRACT FROM AUTHOR]

The counter-intuitive properties of quantum mechanics have the potential to revolutionize information processing by enabling the development of efficient algorithms with no known classical counterparts. Harnessing this power requires the development of a set of building blocks, one of which is a method to initialize the set of quantum bits (qubits) to a known state. Additionally, fresh ancillary qubits must be available during the course of computation to achieve fault tolerance. In any physical system used to implement quantum computation, one must therefore be able to selectively and dynamically remove entropy from the part of the system that is to be mapped to qubits. One such method is an ‘open-system’ cooling protocol in which a subset of qubits can be brought into contact with an external system of large heat capacity. Theoretical efforts have led to an implementation-independent cooling procedure, namely heat-bath algorithmic cooling. These efforts have culminated with the proposal of an optimal algorithm, the partner-pairing algorithm, which was used to compute the physical limits of heat-bath algorithmic cooling. Here we report the experimental realization of multi-step cooling of a quantum system via heat-bath algorithmic cooling. The experiment was carried out using nuclear magnetic resonance of a solid-state ensemble three-qubit system. We demonstrate the repeated repolarization of a particular qubit to an effective spin-bath temperature, and alternating logical operations within the three-qubit subspace to ultimately cool a second qubit below this temperature. Demonstration of the control necessary for these operations represents an important step forward in the manipulation of solid-state nuclear magnetic resonance qubits. [ABSTRACT FROM AUTHOR]

Modeling and optimization of bulk SiGe thin-film coolers are described. Thin-film coolers can provide large cooling power densities compared to commercial thermoeleclrics. Thin-film SiGe coolers have been demonstrated with maximum cooling of 4°C at room temperature and with cooling power density exceeding 500 W/cm². Important parameters in the design of such coolers are investigated theoretically and are compared with experimental data. Thermoelectric cooling, joule heating, and heat conduction are included in the model as well as non-ideal effects such as contact resistance, geometrical effects, and three-dimensional thermal and electrical spreading resistance of the substrate. Simulations exhibit good agreement with experimental results for bulk Si and SiGe thin-film coolers. It turned out that in many spot cooling applications using two n- and p-elements electrically in series and thermally in parallel does not give significant improvement over single leg elements. This is in contrast to conventional thermoelectric modules and is due to the aspect ratio and special geometry of thin film coolers. With optimization of SiGe thin-film cooler, simulations predict it can provide over 16°C with cooling power density of over 2000 W/cm². [ABSTRACT FROM AUTHOR]

The trend towards increasing heat flux at the chip and module level in computers is continuing. This trend coupled with the desire to increase performance by reducing chip operating temperatures presents a further challenge to thermal engineers. This paper will provide an assessment of the potential for module cooling enhancement with thermoelectric coolers. A brief background discussion of thermoelectric cooling is provided citing some of the early history of thermoelectrics as well as more recent developments from the literature. An example analyzing cooling enhancement of a multichip module package with a thermoelectric cooler is discussed. The analysis utilizes closed form equations incorporating both thermoelectric cooler parameters and package level thermal resistances to relate allowable module power to chip temperature. Comparisons are made of allowable module power with and without thermoelectric coolers based upon either air or water module level cooling. These results show that conventional thermoelectric coolers are inadequate to meet the requirements. Consideration is then given to improvements in allowable module power that might be obtained through increases in the thermoelectric figure of merit ZT or miniaturization of the thermoelectric elements. [ABSTRACT FROM AUTHOR]

The deformation of material and friction between the roll and deforming material contact region produce a large amount of heat. This heat energy is conducted toward the roll and the workpiece (strip). A well-designed cooling system is needed to control the material properties and grain structure of the rolled product. Therefore, complete knowledge of the temperature distribution in both the roll and strip is necessary to design an efficient cooling system to control the material properties. In this work, both the roll and strip have been modeled as a coupled heat transfer problem to predict the temperature distribution. Using a finite-volume approach, the governing differential equations as well as the boundary conditions are discretized, which are then solved numerically to predict the temperature distributions. The stability of the solution was examined by changing the grid sizes in the bite region; in addition, the numerical results are validated against published work in the literature for certain special operating conditions. The impact of roll speed and heat transfer coefficient on the distribution of heat flow in both the roll and workpiece are demonstrated through the temperature contour plots. [ABSTRACT FROM AUTHOR]

Magnesium/calcium data from Southern Ocean planktonic foraminifera demonstrate that high-latitude (∼55°S) southwest Pacific sea surface temperatures (SSTs) cooled 6° to 7°C during the middle Miocene climate transition (14.2 to 13.8 million years ago). Stepwise surface cooling is paced by eccentricity forcing and precedes Antarctic cryosphere expansion by ∼60 thousand years, suggesting the involvement of additional feedbacks during this interval of inferred low-atmospheric partial pressure of CO[sub 2] (pCO[sub 2]). Comparing SSTs and global carbon cycling proxies challenges the notion that episodic pCO[sub 2] drawdown drove this major Cenozoic climate transition. SST, salinity, and ice-volume trends suggest instead that orbitally paced ocean circulation changes altered meridional heat/vapor transport, triggering ice growth and global cooling. [ABSTRACT FROM AUTHOR]

The structural, thermal and magnetic properties of the perovskite-type alkaline-earth manganites of the series Sr1-xCaxMnO3-δ (0⩽x⩽1) were investigated. SrMnO3-δ forms a hexagonal perovskite lattice and shows a first-order transformation to a highly defective cubic high-temperature modification. By substituting Ca for Sr (x>0.25) the hexagonal perovskite is suppressed and a cubic (or orthorhombic) lattice becomes stabilized for all temperatures. For x=0.5 and 0.75 cubic perovskites with a large nonstoichiometry (e.g., δ=0.25 for x=0.5) are obtained at 1400 °C. The defective perovskites are prepared by either quenching from high temperature or by cooling in an inert atmosphere. The oxygen vacancies are easily filled by subsequent reoxidation at low temperature (400–600 °C) and stoichiometric samples are obtained. Orthorhombic perovskites are formed at T⩽1200 °C with the nonstoichiometry δ increasing with increasing temperature (e.g., δ=0.06 at 1000 °C and δ=0.14 at 1200 °C for x=0.5). Slow cooling in air results in almost complete reoxidation (δ=0). CaMnO3-δ is an orthorhombic perovskite with a large range of nonstoichiometry (0⩽δ⩽0.30). The cubic to hexagonal phase transformation of the Sr-rich samples is accompanied by a large expansion of the lattice that is reduced by Ca substitution. The Ca/Sr-manganites are antiferromagnets with TN of 170 K for x=0.5 and δ=0.02 and 120 K for x=1 and δ=0.05. [Copyright &y& Elsevier]

Computers are rapidly becoming faster and more versatile, and as a result, high-powered integrated circuits have been produced in order to meet this need. However, these high-speed circuits are expected to generate heat fluxes that exceed the circuit's allowable operating temperature, and so an innovative cooling device is needed to solve this problem. Microchannel heat sinks were introduced in the early 1980s to be used as a means of cooling integrated circuits. Since then, many studies have been conducted in the field of these microchannel heat sinks. Earlier research used mainly single-phase coolants in their heat sinks, but two-phase coolants are now the focus of more recent research. The purpose of this article is to present a state-of-the art literature review of the progress of research in the field of microchannel heat sinks. This literature will focus mainly on the most recent research, starting with the latter half of the 1990s. [ABSTRACT FROM AUTHOR]