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Hot carrier solar cells could offer a solution to achieve high efficiency solar cells. Due to the hot-phonon bottleneck in perovskites, the hot carrier lifetime could reach hundreds of ps. Such that exploring perovskites could be a good way to promote hot carrier technology. With the incorporation of large organic cations, the hot carrier lifetime can be improved. By using ultrafast transient spectroscopy, the hot carrier relaxation and extraction kinetics are measured. From the transient kinetics, 2-phenyl-acetamidine cation based perovskites exhibit the highest initial carrier temperature, longest carrier relaxation, and slowest hot carrier relaxation. Such superior behavior could be attributed to reduced electron–phonon coupling induced by lattice strain, which is a result of the large organic cation and also a possible surface electronic state change. Our discovery exhibits the potential to use large organic cations for the use of hot carrier perovskite solar cells. [ABSTRACT FROM AUTHOR]

Preparation of atomic Bose–Einstein condensate (BEC) with tunable interactions in a quasi-one-dimensional (quasi-1D) optical trap is essential for both the observation of bright matter-wave solitons and the quantum simulation based on the discrete atomic momentum states. However, the quasi-1D BEC has been obtained by a complex process, which includes the creation of a three-dimensional BEC and its adiabatic transform into a quasi-1D trap. Here, we report the direct creation of a quasi-1D BEC of 133 Cs atoms by the fast evaporative cooling of ultracold atoms prepared by the degenerated Raman sideband cooling. We produce the pure BEC of up to 5.5 × 10 4 atoms in a quasi-1D optical trap with an evaporative time of 6 s. We demonstrate the anisotropic expansion of the atomic cloud after the release from the quasi-1D trap and study the dependence of both the phase space density and the temperature on the number of atoms in the trap during the evaporative cooling. Our study facilitates the promising applications of quasi-1D interacting atomic gases. [ABSTRACT FROM AUTHOR]

Elevated air movement produced by fans can offset air-conditioning energy requirements by allowing temperature setpoints to be raised without compromising thermal comfort. These advantages are even greater in hot and humid climates that inherently have large and sustained indoor cooling requirements. Few studies have assessed the in-situ benefits of fans in actual buildings. We installed ceiling and desk fans into a Zero Energy office building (675 m2) in Singapore. Across an 11-week period, 35 occupants alternated between two conditions (no fan vs. fan): 24 °C setpoint with fans off, and 26.5 °C setpoint with fans on. When the temperature setpoint was raised and elevated air movement was provided, a 32% energy reduction was obtained. The energy savings accrued without any negative impacts occurring on thermal satisfaction. Overcooling caused by thermal preference to slightly warmer and warmer conditions was substantially reduced from 33 to 9%. No changes in perceived air-staleness or self-reported alertness and ability to concentrate occurred either, indicating parity across the no fan and fan conditions. Although occupants primarily relied on ceiling fans at the 26.5 °C setpoint, they were by default on at the beginning of each day, giving less incentive to use the desk fans. Our study took place in a high-performance Zero Energy building, whereby thermal dissatisfaction was already low (7%). Therefore, notable changes did not occur, but significant improvements to thermal comfort could still occur in buildings that are unable to maintain high levels of thermal satisfaction.

Experiments investigating the properties of deeply supercooled liquid water are needed to develop a comprehensive understanding of water's anomalous properties. One approach involves transiently heating nanoscale water films into the supercooled region for several nanoseconds at a time and then interrogating the water films after they have quenched to cryogenic temperatures. To relate the results obtained with this approach to other experiments and simulations on supercooled water, it is important to understand how closely the quenched structure tracks the (metastable) equilibrium structure of water as a function of the transient heating temperature. A key step involves quantifying the extent to which water that is transiently heated to ambient temperatures [hyperquenched water (HQW)] subsequently relaxes toward the structure of low-density amorphous (LDA) ice as it cools. We analyzed the infrared reflection–absorption spectra of LDA, HQW, and crystalline ice films to determine their complex indices of refraction. With this information, we estimate that HQW retains ∼50%–60% of a structural motif characteristic of water at high temperatures with the balance comprised of a low-temperature motif. This result, along with results from x-ray diffraction experiments on water and amorphous ices, allows one to quantify the fraction of the high-temperature motif at approximately zero pressure as a function of temperature from 150 to 350 K. [ABSTRACT FROM AUTHOR]

The phase transformation mechanism of oxide scale on the surfaces of chromium (Cr)-free carbon steel and 0.9 wt% Cr-containing steel at different coiling temperatures and cooling rates was studied using thermal simulation and electron backscattering diffraction experiments. The results showed that the eutectoid transformation of both the steel followed the “C” curve relationship. The Cr-containing steel had a larger eutectoid transformation area fraction than the Cr-free carbon steel. The nose tip temperature of the eutectoid transformation of the oxide scale on the surfaces of Cr-free carbon steel and 0.9 wt% Cr-containing steel were 420∼510 °C and 420–480 °C, respectively. For the 0.9 wt% Cr-containing steel, the proportion of Σ3 and Σ13b grain boundaries in cubic Fe3O4 increased, followed by a decrease, when the coiling temperature decreased from 610 to 410 °C. The Σ3 and Σ13b grain boundaries of the Fe3O4 low-dimensional coincident site lattice had the highest proportion for 510 °C coiling temperature. The low-dimensional coincident site lattice grain boundaries could be used to enhance crack resistance and improve the oxide scale on the steel plate surface.

The research conducted deals with the use of an aluminum heat sink, which is usually used to cool electronic cores and integrated circuits, to cool a solar cell and study the effect of microprocessors and integrated circuits on the performance and temperature of the cell. In this study, an experiment was carried out and simulated using computational fluid dynamics. The results showed that increasing the temperature of the solar cell leads to an accelerated decrease in the open circuit voltage, but when a heat sink is used, the increasing temperature of the cell is reduced more slowly over the same period. Thus, the open circuit voltage drop is reduced more slowly as well, which means the cell operates more efficiently under the same conditions. The temperatures are 290 K at the lowest point and 350 K at the highest point, which shows that heat is being dissipated from the solar cell to the heat sink. It is evident that as the heat sink's number of fins increases, the rate at which heat is transferred increases because the enhanced heat transfer that results from having more fins lowers the heat sink's temperature. These findings can help improve the efficiency of solar power generation and increase the efficiency of solar cells in converting solar energy into electrical energy.

Abstract Grinding, a critical precision machining process for difficult-to-cut alloys, has undergone continual technological advancements to improve machining efficiency. However, the sustainability of this process is gaining heightened attention due to significant challenges associated with the substantial specific grinding energy and the extensive heat generated when working with difficult-to-cut alloys, renowned for their exceptional physical and mechanical properties. In response to these challenges, the widespread application of massive coolant in manufacturing industries to dissipate grinding heat has led to complex post-cleaning and disposal processes. This, in turn, has resulted in issues such as large energy consumption, a considerable carbon footprint, and concerns related to worker health and safety, which have become the main factors that restrict the development of grinding technology. This paper provides a holistic review of sustainability in grinding difficult-to-cut alloys, encompassing current trends and future directions. The examination extends to developing grinding technologies explicitly tailored for these alloys, comprehensively evaluating their sustainability performance. Additionally, the exploration delves into innovative sustainable technologies, such as heat pipe/oscillating heat pipe grinding wheels, minimum quantity lubrication, cryogenic cooling, and others. These groundbreaking technologies aim to reduce dependence on hazardous coolants, minimizing energy and resource consumption and carbon emissions associated with coolant-related or subsequent disposal processes. The essence of these technologies lies in their potential to revolutionize traditional grinding practices, presenting environmentally friendly alternatives. Finally, future development trends and research directions are put forward to pursue the current limitation of sustainable grinding for difficult-to-cut alloys. This paper can guide future research and development efforts toward more environmentally friendly grinding operations by understanding the current state of sustainable grinding and identifying emerging trends.

We monitor the transformation of a liquid into an amorphous solid in simulations of a glass forming liquid by measuring the variation of a structural order parameter with either changing temperature or potential energy to establish the influence of the cooling rate on amorphous solidification. We show that the latter representation, unlike the former, exhibits no significant dependence on the cooling rate. This independence extends to the limit of instantaneous quenches, which we find can accurately reproduce the solidification observed during slow cooling. We conclude that amorphous solidification is an expression of the topography of the energy landscape and present the relevant topographic measures. [ABSTRACT FROM AUTHOR]

Narrow bandgap nanocrystals (NCs) are now used as infrared light absorbers, making them competitors to epitaxially grown semiconductors. However, these two types of materials could benefit from one another. While bulk materials are more effective in transporting carriers and give a high degree of doping tunability, NCs offer a larger spectral tunability without lattice-matching constraints. Here, we investigate the potential of sensitizing InGaAs in the mid-wave infrared throughout the intraband transition of self-doped HgSe NCs. Our device geometry enables the design of a photodiode remaining mostly unreported for intraband-absorbing NCs. Finally, this strategy allows for more effective cooling and preserves the detectivity above 108 Jones up to 200 K, making it closer to cryo-free operation for mid-infrared NC-based sensors. [ABSTRACT FROM AUTHOR]

Rotating machinery like gas turbine engines consist of rotating components like gas turbine disks that are exposed to high thermal loads and stresses due to centrifugal force acting on them, and thus effective cooling is essential. The disks are additionally exposed to hot turbine gas ingress as an adverse pressure gradient is created in the stator-rotor cavity due to outward pumping of near-disk flow. Impingement of a coolant jet on such a surface can effectively provide cooling and also counter this adverse gradient. There also exists a circular relative velocity between the disk and wall-jet formed by impinging air as well as the air in the disk vicinity. Thus, the study of heat transfer under rotating conditions becomes important. With the advent of advanced manufacturing techniques, it is possible to produce disks with novel heat transfer enhancement features such as pin-fins which have not been previously explored. They create unique flow features in addition to increasing the surface area. The present study numerically investigates the heat transfer over rotating surfaces under jet impingement with square, triangular, cylindrical and dome-shaped pin-fins. This will inform the optimization of pin geometry for better heat transfer effectiveness and uniformity. Three different jet Reynolds numbers between 5000 and 18000 based on the jet diameter have been studied for three different Rotational Reynolds numbers based on the disk diameter. Transient non-conjugate heat transfer analysis was conducted, and the technique was compared with experimental results on square pin-fins and a smooth circular disk. The heat transfer enhancement greatly depends on the flow separation and pin area normal to the flow. A heat transfer enhancement of close to 2.2 was observed for triangular fins for the lowest rotation speed, for the highest rotation speed, the highest enhancement of close to 1.7 was observed in the cylindrical pins. [ABSTRACT FROM AUTHOR]

Engineering the spectral response of materials in infrared (IR) wavelength range can enable effective radiative cooling. Current configurations of IR emitters usually adopt complicated photonic designs and engineered structures because pure/singular materials such as dielectrics and polymers can hardly realize broadband and spectrally selective emissivity simultaneously. Herein, we propose single-layer silicon oxynitride (SiON) coatings with visible transparency and outstanding broadband spectral emissivity of 0.8–0.9 in the wavelength range of 8–14 μm. The single layered composite coating has a thickness below 2 μm, and its mid-IR broadband absorption characteristics can be tuned by adjusting the chemical intermixing of SiO2 and SiN as well as proportion of the Si–O and Si–N bonds during the physical and chemical vapor deposition processes, respectively. When deposited on solar reflective substrate, the composite coating with highest selective emissivity of 0.9 shows a promising net cooling power of ≥ 120 W m−2, when the ambient temperature is 27 °C. In an outdoor experiment, the selective emitter exhibits 4.5–5 °C lower temperature when compared to the ambient temperature inside the chamber, thus achieving the sub-ambient daytime cooling. Therefore, absorption bandwidth extension of single material provides a feasible cooling solution for many applications, including solar cells, and building and automobile windows. [ABSTRACT FROM AUTHOR]

Sufficiently cold-water temperatures (<7°C) are needed to elicit the sympathetic response to the cold pressor test using the hand. However, it is not known if stimulating the trigeminal nerve via face cooling, which increases both sympathetic and cardiac parasympathetic activity, also has a threshold temperature. We tested the hypothesis that peak autonomic activation during a progressive face cooling challenge would be achieved when the stimulus temperature is ≤7°C. Twelve healthy participants (age: 25 ± 3 yr, four women) completed our study. Six pliable bags, each containing water or an ice slurry (34°C, 28°C, 21°C, 14°C, 7°C, and 0°C) were applied sequentially to participants’ forehead, eyes, and cheeks for 5 min each. Mean arterial pressure (photoplethysmography; index of sympathetic activity) and heart rhythm (3-lead ECG) were averaged in 1-min increments at the end of baseline and throughout each temperature condition. Heart rate variability in the time [(root mean square of successive differences (RMSSD)] and frequency [high-frequency (HF) power] domains was used to estimate cardiac parasympathetic activity. Data are presented as the increase from baseline ± SD. Mean arterial pressure only increased from baseline in the 7°C (13.1 ± 10.3 mmHg; P = 0.018) and 0°C (25.2 ± 7.8 mmHg; P < 0.001) conditions. Only the 0°C condition increased RMSSD (160.6 ± 208.9 ms; P = 0.009) and HF power (11,450 ± 14,555 ms2; P = 0.014) from baseline. Our data indicate that peak increases in sympathetic activity during face cooling are initiated at a higher forehead skin temperature than peak increases in cardiac parasympathetic activity.NEW & NOTEWORTHY Using a progressive face cooling challenge, we demonstrated that peak sympathetic activation occurs at a higher forehead skin temperature (forehead temperature: 19°C; stimulus temperature: 7°C) than peak cardiac parasympathetic activation (forehead temperature: 11°C; stimulus temperature: 0°C). Therefore, we suggest using a sufficiently cold stimulus (∼0°C ) when using face cooling to interrogate autonomic activation to stimulate both the sympathetic and cardiac parasympathetic nervous systems. [ABSTRACT FROM AUTHOR]

The article presents the design of a four-way valve, implemented in SolidWorks software (SOLIDWORKS® i 3DEXPERIENCE® Works Simulation) and used for central heating installations in buildings. The project was carried out in order to examine the innovative design of the medium mixing mechanism and to conduct strength and FMEA analysis. The innovative solutions proposed by the authors in this work will allow valves of this type to meet stringent environmental standards. These standards are currently being introduced for this type of structural element of machine parts as part of the energy transformation of buildings. Potential failures occurring in individual elements of the four-way valve were also tested using Failure mode and effects analysis. In addition, strength tests were performed in SolidWorks software using static analysis, and optimization tests were performed on the refrigerant in terms of its impact on the environment. The characteristics of the tested materials in the valve design show that the best materials are brass and stainless steel. Brass has a Poisson's ratio of 0.33, a tensile strength of 478.4 MPa and a yield strength of 239.7 MPa. In turn, stainless steel is characterized by the following parameters: Poisson's ratio of 0.27, tensile strength of 685 MPa and yield strength of 292 MPa. The designed valve reduces energy consumption by 30% through a properly designed medium flow with the appropriate selection of materials. Moreover, the design reduces the thickness of the contaminant layer by 0.17 mm, with a capacity factor of −2.50% and an evaporator Δp of 3.10% (53 kPa). The performed research provides knowledge on the subject selection of appropriate material, a description of the potential failures of the structural elements of the designed four-way valve and methods of counteracting these failures. The article presents the optimization role of the tested component in the context of sustainable development. [ABSTRACT FROM AUTHOR]

Developing passive radiative cooling fabrics could effectively prevent the harmful consequences of global warming, including heat stress and other related illnesses. By enhancing the material compositions and optimizing the structural parameters of conventional fabrics, the creation of radiative cooling fabric that offers both comfort and durability holds great potential. However, the researched simulation models are over‐simplistic, rendering it challenging to precisely portray the fine fabric's structure with the low accuracy of optical properties prediction. In this work, a high‐fidelity model is developed for fabric structure, which allows for precise control of structural parameters of fiber, yarn, texture, and doping particles. Subsequently, by utilizing the FDTD Solutions software, the optical performance of the fabric model is successfully addressed. Furthermore, the coupled heat transfer equation is employed to determine the actual cooling effect of the fabric. It is observed that doping 1% TiO2 nanoparticles and increasing the number of fibers significantly enhances the solar reflectivity, resulting in a cooling effect of approximately 2 °C. To maintain the skin temperature of 34°C, the additional cooling energy required would be reduced by 36 W m−2. These findings are expected to provide crucial guidance and predictions for the development of passive radiative cooling fabrics. [ABSTRACT FROM AUTHOR]

Pesticides are used to control agricultural and industrial pests, and even combat diseases such as malaria, posing a serious threat to public health and many aspects of life. Therefore, identification, extraction, and preconcentration play a crucial role in the determination and measurement of these compounds. The cooled-heated device headspace solid-phase microextraction technique provides preconcentration of volatile and semi-volatile compounds. The aim of this research is to design and fabricate a new device for the simultaneous cooling of the fiber and evaporated sample and extracting pesticides. The innovative technique was evaluated by the extraction and gas chromatography mass spectrometry determination of chlorpyrifos, deltamethrin, fenvalerate and cypermethrin in soil samples. Optimization of the effective extraction parameters was carried out by the simplex method. Under the optimized conditions (i.e., cold and heat temperature of –10 and 70°C, water addition of 20 µL, and extraction time of 15 min), relative standard deviations of 3.94 to 6.51% were obtained of the studied compounds in five replicated analyses. The prepared fiber was stable and could be used several times without any significant change in its efficiency. [ABSTRACT FROM AUTHOR]

Background: Some people with multiple sclerosis (pwMS) avoid exercise due to overheating. Evidence from a variety of cooling treatments shows benefits for pwMS. Objective: Conduct a randomized controlled trial of antipyretic treatment before exercise in pwMS. Methods: Adults over age 18 diagnosed with relapsing–remitting MS reporting heat sensitivity during exercise were randomly assigned to one of six sequences counterbalancing aspirin, acetaminophen, placebo. At each of three study visits separated by ≥ one week, participants received 650-millograms of aspirin, acetaminophen, or placebo before completing a maximal exercise test. Primary outcomes were body temperature change and total time-to-exhaustion (TTE), secondary outcomes were physiological and patient-reported outcomes (PROs). Results: Sixty participants were enrolled and assigned to treatment sequence; 37 completed ≥ one study visit. After controlling for order effects, we found that body temperature increase was reduced after aspirin (+ 0.006 ± 0.32 degrees Fahrenheit, p < 0.001) and after acetaminophen (+ 0.31 ± 0.35; p = 0.004) compared to placebo (+ 0.68 ± 0.35). TTE after aspirin (331.6 ± 76.6 s) and acetaminophen (578.2 ± 82.1) did not differ significantly from placebo (551.0 ± 78.4; p's > 0.05). Aspirin benefited all secondary outcomes compared to placebo (all p's < 0.001); acetaminophen showed broadly consistent benefits. Conclusion: These results support antipyretic treatment as effective for reducing overheating during exercise in pwMS and failed to support antipyretics for increasing TTE in the context of a maximal exercise test. Benefits were shown for physiological markers of exercise productivity and PROs of fatigue, pain, and perceived exertion. [ABSTRACT FROM AUTHOR]

Background The aim of this study is to investigate the different approaches to thermal challenges, both cold and warm, used in dynamic infrared thermography for reconstructive surgery, and explore whether it affects the success of preoperative perforator mapping. Methods Literature was collected from Ovid Medline, Embase, PubMed, and Cochrane. The references of the full-text articles located from the original search were also appraised. Thirteen articles were extracted for the final qualitative analysis. A systematic review was then conducted following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Results Thirteen articles looked at a cold challenge, which included airflow cooling, direct contact cooling, and evaporation-based cooling. Two articles investigated warm challenges. One paper used no challenge, suggesting it unnecessary with a highly sensitive camera. All cold challenges were positively supported by a high level of flap perfusion success and/or a high level of correlation with other forms of investigation. Conclusion Cold challenges were overall superior to no challenge and warm challenges; however, this conclusion is limited by the small participant size, the possibility of detection bias, and poor methodology detailing. Airflow cooling—specifically, using a desktop fan to blow air for 2 minutes—was noted to likely cause the least discomfort due to a low cooling capacity yet simultaneously maintain effectiveness and allow for a uniform cooling application. Warm challenges showed less conclusive results and were restricted by lack of studies. This topic would benefit from larger scale studies that compare multiple approaches while using standardized equipment to eliminate confounding factors. [ABSTRACT FROM AUTHOR]

In the present work a numerical analysis is presented to identify the separate effect of cooling by radiation and convection, in evaporative meat weight loss during beef carcass cooling process. A transient heat and mass transfer model is proposed using a 3D beef side geometry. Water activity variations are incorporated in the model. Convective coefficients are obtained from correlations by considering buoyancy effect due to temperature and vapor concentration gradients, and forced air flow. For the purpose of model water mass diffusion into the carcass, a first approximation of the meat layer thickness affected by drying is obtained from an analytical analysis as a semi-infinite solid. The model is solved numerically and it is validated with experimental data from the literature. Results of heat load and weight loss are compared to models proposed by other authors. Temperature and surface water activity evolution, and temperature and water content profiles are analyzed also. Finally, a sensitivity study is carried out on the main result of the model, total evaporated mass, varying heat convection coefficient and radiative cooling. It is found that there is a convective heat transfer coefficient that maximize the evaporative losses, so it is important to operate far from this point in order to reduce the evaporated mass. Furthermore, radiation during the meat cooling process turns out to be an interesting method to rapidly cool meat without increasing the evaporated mass (radiation cooling). Results shows that combining properly the convection and radiation heat transfer, evaporation losses can be reduced. • A simplified model to predict beef side weight loss is validated. • Both natural and forced convection are relevant during meet chilling process. • An upper limit of meat thickness affected by drying is analytically estimated. • There is a convective coefficient value that maximizes weight loss. • Theoretically a reduction in evaporated mass might be achieved by radiative cooling. [ABSTRACT FROM AUTHOR]

Zirconolite (CaZrTi 2 O 7) glass-ceramic is considered as a potential stable matrix for the immobilization of Pu or minor actinides (Np, Am, Cm). In this work, the phase combination and evolution of glass (SiO 2 –Al 2 O 3 –Na 2 O–CaO–ZrO 2 –TiO 2 –B 2 O 3) with La as an actinide surrogate were investigated during the process of heating and cooling. By employing controlled cooling process, the zirconolite glass-ceramic with a controllable crystal size was successfully fabricated in borosilicate glass. The results demonstrate that heating and cooling exhibit distinct phase combinations. Both crystallization temperature and duration exert a significant influence on the composition of crystalline phases and microstructure. During the cooling of the melt, an increased degree of supercooling leads to an enhanced crystallization of zirconolite and a significant reduction in crystal size. The experimental results demonstrate that the optimal condition for preparing zirconolite glass-ceramic is held at 950 °C, for 4 h by one-step method, at which time the crystal exhibits a slender acicular morphology with a size of about 30 μm. Most of the simulated nuclides are enriched in crystals, and the rest are dissolved in glass. Zirconolite exhibits thermodynamic instability at elevated temperatures (1000 °C–1100 °C). Following the phase transformation, a proportion of Zr sequestered by titanite, while any excess Zr is either remain dissolved in the glass or gets precipitated as baddeleyite. For La, Al and other elements previously fixed in zirconolite, they are re-released to the glass and partially fixed by titanite, which may be detrimental to the long-term release behavior of the waste forms. In the aqueous durability test, both zirconolite glass-ceramic and phase transformation samples exhibited a low leaching rate, with LR Si , LR Zr , and LR La values of approximately 5 × 10−3, 4 × 10−6, and 6 × 10−6 g·m−2·d−1, respectively, after 28 days of leaching. By controlling the cooling process (one-step method), this paper provides useful information on the preparation of zirconolite glass-ceramic. [ABSTRACT FROM AUTHOR]

Hypersonic air-breathing propulsion (>Mach 5) based on scramjet offers new solutions to both the military strike platform and the civil transportation. However, the hypersonic flight seriously challenges the engine thermal protection. One of the key problems is the tricky flow and thermal behaviors of hydrocarbon fuel in regenerative cooling channels under the complex thermal boundaries and channel geometry, which may cause heat transfer deterioration and structure over-temperature. To improve the cooling design, the double-layer regenerative cooling channels are focused and compared with the traditional single-layer channels. The flow and thermal behaviors of hydrocarbon fuel under different cooling configurations are numerically studied. Cooling performance of double-layer channels is superior than single-layer channels. Tw,max falls by 295.2 K/17.7%. Gravity direction and magnitude show negligible influence on the heat transfer. Regarding channel height ratio, H1/H2 = 1.1/1 achieves optimal cooling performance in present conditions. Double-layer-channel scheme presents high practicability in scramjet cooling. [ABSTRACT FROM AUTHOR]

The impact of embedded microfluidic cooling on the performance of Ku-band gallium nitride (GaN) microwave monolithic integrated circuit (MMIC) power amplifiers (PAs) has been studied in this work. The research demonstrates that embedded cooling can substantially lower junction temperatures, mitigate the self-heating effect, and thereby improve the electrical performance of GaN MMIC PAs. Using merely 10.4 mW of pumping power (Ppump), the technology reduces the maximum junction temperature (Tj,max) from 216.7 to 147.8 °C. Furthermore, the system enhances the saturation current by 13.8%, increases output power (Pout) and gain (Gain) by 1.8 dB, elevates the power added efficiency (PAE) by 5.9%, and improves the heat flux of last gate (Qgate) to 37.3 kW/mm2 and the heat flux of MMIC (QMMIC) over 2.6 W/mm2, while reducing the thermal resistance (Rj-c) from 2.13 to 1.26 °C/W. Additionally, there is a notable improvement of the small signal gain (S21) by 2.5 dB. Therefore, the achievements in this work indicate that embedded cooling offers a powerful technique to suppress the thermal effects on GaN MMIC PAs, consequently improving their electrical performance. [ABSTRACT FROM AUTHOR]

The macrosegregation evolution kinetics of undercooled Cu60Fe40 immiscible alloy during slow cooling and rapid cooling processes were investigated by laser heating and glass fluxing techniques. The critical undercooling for the occurrence of metastable phase separation (MPS) was determined as 41 K. As the undercooling rised, MPS always occurred even if the undercooling rised to the largest value of 482 K (0.28 TL) and the nucleation temperature of primary phase was below the peritectic temperature for the first time. Meanwhile, both the phase separation time and the volume fraction of Fe-rich zone gradually increased under the two conditions. However, the phase separation time and the volume fraction of Fe-rich zone under the laser heating condition were much smaller than that under the glass fluxing state. At slight undercoolings, MPS preferentially happened at the bottom region of laser-heated sample and glass-fluxed sample, and the microstructure in other regions appeared as well-defined αFe dendrites in the (Cu) matrix phase. In highly undercooled state, macrosegregation morphologies composed of floating Fe-rich zones and sinking Cu-rich zones were preserved. The critical undercooling for the macrosegregation formation of glass-fluxed sample was relatively larger. Moreover, the Fe-rich zone completely floated to the top of glass-fluxed sample while that located in the middle region of laser-heated sample. The higher the bulk undercooling, the lower the lattice constant of (Cu) phase and the greater the lattice constant of αFe phase. The calculations and analyses of temperature field and fluid dynamics demonstrated that the difference of heat transfer mechanisms between laser-heated sample and glass-fluxed sample was responsible for the distinctions of macrosegregation evolution kinetics in the two experiments. [ABSTRACT FROM AUTHOR]

The escalating demand for electric vehicles and lithium-ion batteries underscores the critical need for diverse battery thermal management systems (BTMSs) to ensure optimal battery performance. Despite this, a comprehensive comparative analysis remains absent. This study seeks to assess and compare the thermal and hydraulic performances of three prominent BTMSs: fin cooling, intercell cooling, and PCM cooling. Simulation models were meticulously developed and experimentally validated, with each system's design parameters optimized under identical volumes to ensure equitable comparisons. In the context of fast-charging conditions, intercell cooling consistently met and even surpassed the desired target temperature, reducing the maximum temperature to 30.6°C with an increasing flow rate, while fin cooling faced challenges. Effective control of coolant temperature emerged as a critical factor for achieving optimal PCM cooling, with a potential reduction in temperature difference by 4.3 K. Despite exhibiting higher power consumption, intercell cooling demonstrated the most efficient cooling effect during fast charging. Considering the BTMS weight, fin cooling exhibited the lowest energy density, approximately half that of other methods. Addressing precooling and preheating conditions for high and low temperatures, the intercell method proved adept at meeting temperature requirements with minimal power consumption in significantly shorter durations. Conversely, the practicality of using PCM at high temperatures was deemed challenging. [ABSTRACT FROM AUTHOR]

This study offers a comprehensive assessment of the thermodynamic performance of a novel solar-based multigeneration system, which caters to the energy needs of a sustainable community by producing electricity, cooling, heating, and freshwater. The solar-based multigeneration system is comprised of four main components: the thermal subsystem of the parabolic trough collector (PTC) employing CO2 as a heat transfer fluid, a single-effect absorption refrigeration cycle (ARC), a supercritical CO2 (S-CO2) cycle, and an adsorption desalination (AD) cycle with heat recovery employing aluminum fumarate metal-organic framework (MOF) adsorbent material. A comprehensive parametric study was performed on the proposed solar-based multigeneration system by varying key parameters to evaluate its performance. It is found that the thermal and exergy efficiencies of a PTC were evaluated to be 68.35% and 29.88%, respectively, at a fixed inlet temperature of 225 °C and solar irradiation of 850 W/m² and also a slight reduction in the ARC cycle when examining the variation in the thermal and exergetic COPs for the generator temperature. Additionally, the thermal and exergy efficiencies of electricity, cooling, and heating were determined to be 20.41% and 21.93%, 41.34% and 3.51%, and 7.14% and 3.07%, respectively, at the operating condition. The maximum specific daily water production (SDWP) value of 12.91 m³/ton/day and a gain output ratio (GOR) of 0.64 were obtained under steady operating conditions in the AD cycle. [ABSTRACT FROM AUTHOR]

The layout of multiple natural draft dry cooling towers could have a significant influence on the performance of the cooling system in concentrated solar power (CSP) plants; however, this has never been quantified. Hence, this work used computational fluid dynamics (CFD) modeling to analyze the cooling capacity of two short natural draft dry cooling towers (NDDCTs) on a common site for a range of tower spacings, wind-speeds, and wind incidence angles. The results show that the cooling performance of the towers is a strong function of tower spacing and their orientation with respect to the wind direction. It was found that when the wind came at a 90-deg wind incidence angle (i.e., normal to a line drawn between the two towers), their cooling capacity was improved at tower spacings of less than 1.8 tower diameters (1.8D), though for the other tower spacings, there was no interaction between the towers. However, with the wind at 45 deg to the towers, the flow around the towers resulted in a decrease in their cooling capacity at tower spacings of 1.8D and 2.6D. Most interestingly, it was found that orienting the towers in line with the prevailing wind direction delivered improvements in the cooling capacity of up to 30%. This is due to the windward tower acting as a passive windbreak. Hence, as CSP plant capacity is increased, and additional cooling towers are required, these should be placed close to any existing tower and oriented along the line of the prevailing winds. [ABSTRACT FROM AUTHOR]

The issues of the environmental evolution of the western sector of the Khanka valley and the evolution of Lake Khanka are considered for the maxima of the last glaciation and Late Pleistocene lacustrine transgression. The lithological indicators and results of diatom analysis of lacustrine sediments of Lake Khanka indicate two sedimentation conditions over the period of 24.0–19.0 cal ka BP: an oligotrophic–mesotrophic moderately swampy shallow reservoir with an unstable level and a relatively deep lake. The maximum of the transgression occurred at ~19.6 cal ka BP, when the lake level was 1.5–2.0 m higher than at present for the first time. Four phases of the vegetation evolution in the western sector of the Khanka valley are distinguished: I, birch–larch mari with alder and frigid shrubs (23.8–22.8 cal ka BP); II, dark coniferous taiga with dwarf pine and a small amount of broad-leaved trees (22.8–20.6 cal ka BP); III, spruce forests with dwarf pine, fir, larch, and rare oak (20.6–20.1 cal ka BP); and IV, light birch forests and larch mari with frigid shrubs (20.1–19.0 cal ka BP). Two cooling phases are registered at the Khanka valley (~24.0 cal ka BP (cooling maximum) and 20.6 cal ka BP) and one warming phase (∼22.8 cal ka BP), which are correlated with the detailed global Greenland glacier records. The driest periods occurred at 21.7–21.2 cal ka BP. The quantitative characteristics of climate events are reconstructed from modern plant analogs. [ABSTRACT FROM AUTHOR]

A field campaign in a valley near Seefeld, Austria, well known for the frequent occurrence of cold‐air pools, was conducted to identify the processes leading to the formation and erosion of the cold‐air pool. Here, we focus on a case study in January 2020 that featured cold‐air pool formation interrupted by a wind disturbance. Simulations with the Weather Research and Forecasting model were performed at a horizontal grid spacing of 40 m and compared with measurement results. The model was able to reproduce the intense cooling in the beginning of the night and the cold‐air pool erosion in the middle of the night caused by the wind disturbance, but stronger winds than observed prevented the cold‐air pool from fully re‐establishing in the model after the disturbance. The dominant cooling processes were long‐wave radiative heat loss and turbulent exchange, both of which are parametrized and cool the air locally. Advection was the most important warming contribution during the cold‐air pool disturbances, especially its cross‐valley and vertical components. Owing to numerical constraints and the shallow nature of the cold‐air pool, its extent was limited to the lowest model level. Further improvements to the cold‐air pool's representation in the model would require a finer grid resolution. [ABSTRACT FROM AUTHOR]

The benefits of cold have long been recognized in sport and medicine. However, it also brings costs, which have more rarely been investigated, notably in terms of sensorimotor control. We hypothesized that, in addition to peripheral effects, cold slows down the processing of proprioceptive cues, which has an impact on both feedback and feedforward control. We therefore compared the performances of participants whose right arm had been immersed in either cold water (arm temperature: 14°C) or lukewarm water (arm temperature: 34°C). In experiment 1, we administered a Fitts's pointing task and performed a kinematic analysis to determine whether sensorimotor control processes were affected by the cold. Results revealed 1) modifications in late kinematic parameters, suggesting changes in the use of proprioceptive feedback, and 2) modifications in early kinematic parameters, suggesting changes in action representations and/or feedforward processes. To explore our hypothesis further, we ran a second experiment in which no physical movement was involved, and thus no peripheral effects. Participants were administrated a hand laterality task, known to involve implicit motor imagery and assess the internal representation of the hand. They were shown left- and right-hand images randomly displayed in different orientations in the picture plane and had to identify as quickly and as accurately as possible whether each image was of the left hand or the right hand. Results revealed slower responses and more errors when participants had to mentally rotate the cooled hand in the extreme orientation of 160°, further suggesting the impact of cold on action representations. NEW & NOTEWORTHY: We investigated how arm cooling modulates sensorimotor representations and sensorimotor control. Arm cooling induced changes in early kinematic parameters of pointing, suggesting an impact on feedforward processes or hand representation. Arm cooling induced changes in late kinematic parameters of pointing, suggesting an impact on feedback processes. Arm cooling also affected performance on a hand laterality task, suggesting that action representations were modified. [ABSTRACT FROM AUTHOR]

Today, when heating or cooling processes are carried out, environmentally harmful refrigerants are used. The Counterflow Ranque-Hilsch Vortex Tube (CFRHVT) consists of a simple tube. In RHVT, the heating and cooling process is done with the help of a pressurized fluid, causing little harm to the environment. In this study, 2, 3, 4, 5 and 6 orifice nozzles made of polyamide and brass materials were used in all experiments. At the same time, data were taken with air and oxygen gases as pressurized fluids during the experiments, and at every 0.5 bar, variables between 1.5bar and 7 bar. With the results obtained in the experiments, predictions were made with Support vector machines (SVM), Gaussian process regression (GPR), Linear regression (LR), Ensemble of Tree (ET) and Regression Trees (RT) models from machine learning methods. Five-fold analyses were performed with the k-fold cross-validation method for the validation processes as a result of the investigation. They obtained the best estimation result with the GSR method with 0.99 in the comparisons made with pressured fluids, oxygen and air, and polyamide and brass as the materials. The results show that the cost of experimental setup can be reduced and significant time savings can be achieved using machine learning. [ABSTRACT FROM AUTHOR]

The present study investigates the impact of integrating mould vibration with the vibration-assisted cooling slope (VCS) process on the microstructural and mechanical properties of A392 alloy and the optimization of process parameters. The optimization is done by considering process parameters such as slope length (300 mm, 400 mm, 500 mm, 600 mm and 700 mm), pouring temperature (680 °C, 690 °C, 700 °C, 710 °C and 720 °C), slope vibration (0 Hz, 15 Hz, 30 Hz, 45 Hz and 60 Hz), mould vibration (0 Hz, 15 Hz, 30 Hz, 45 Hz and 60 Hz) and slope angle (15°, 30°, 45°, 55° and 60°), using the multi-objective method (Taguchi-based grey relational analysis). The output responses (mechanical and microstructural properties) were converted into single objective responses as grey relational grades, and the obtained grades were analysed using Taguchi and ANOVA (analysis of variance). The results revealed that the integration of mould vibration with the vibration-assisted cooling slope process (VCS) improved the microstructure homogeneity and mechanical properties of the A392 alloy. It was observed that the optimum parameters for the VCS-integrated mould vibration process were a slope length of 600 mm, pouring temperature of 700 °C, slope vibration of 45 Hz, mould vibration of 30 Hz and slope angle of 45°. The confirmation test was done with optimum values. The optimization of process parameters resulted in the further enhancement of the properties. The results are very close to the predicted value with a difference of 9%. The findings of this study could provide valuable insights for optimizing the vibration-assisted cooling slope process (VCS) integrated with mould vibration for A392 alloy and similar materials. [ABSTRACT FROM AUTHOR]

In this paper, the experimental results of the thermal sub-system of a reliable and cost-effective polygeneration solar system are presented. This polygeneration system produces heating, cooling, and electricity from solar energy, which is used in an existing test building. Heat is generated in four evacuated tube solar collectors (ETCs). The heat may be used for space cooling through a variable geometry ejector (VGE) heat pump. In order to reduce the mismatches between generation and consumption, two thermal storage tanks were added. The performance of a new thermal storage, with 400 L, able to store both sensible and latent heat, was tested. The heating performances of the test building were assessed. Ejector cycle tests were also performed, and the variation of the cooling coefficient of performance (COP) was calculated for different flow rates. For heating, the results showed that the heat storage was capable of heating the test building for 8 h, with temperatures between 22 °C and 26 °C. All results showed that this polygeneration prototype could be capable of meeting the heating and cooling needs when applied to a real building. [ABSTRACT FROM AUTHOR]

Film cooling technology is of great significance to enhance the performance of aero-engines and extend service life. With the increasing requirements for film cooling efficiency, researchers and engineers have carried out a lot of work on the precision and digital measurement of cooling holes. Based on the above, this paper outlines the importance and principles of film cooling technology and reviews the evolution of cooling holes. Also, this paper details the traditional measurement methods of the cooling hole used in current engineering scenarios with their limitations and categorizes digital measurement methods into five main types, including probing measurement technology, optical measurement technology, infrared imaging technology, computer tomography (CT) scanning technology, and composite measurement technology. The five types of methods and integrated automated measurement platforms are also analyzed. Finally, through a generalize and analysis of cooling hole measurement methods, this paper points out technical challenges and future trends, providing a reference and guidance for forward researches. [ABSTRACT FROM AUTHOR]

This paper presents the design and evaluation of a prototype thermally active student desk (TASD) for personalized cooling retrofits using computational fluid dynamics (CFD) and field experiments. The study first developed an initial conceptual design for a TASD prototype made to esthetically match the desks in an architecture studio in a historic building that is frequently subject to comfort complaints. CFD simulations were used to validate the conceptual design and determine some component and system features. Four functional prototype TASDs for cooling were constructed and tested in the studio space with university students while the rest of the building was maintained at an extended temperature set point. CFD simulations predicted that the percent people of dissatisfied (PPD) would be ≤6% under all simulated scenarios. Surveys of 11 occupants who used the TASD revealed PPD of 9% (1/11), while PPD was 14% (17/120) among participants seated elsewhere in the building. The mean level of satisfaction (LOS) was similar among the two groups and thermal sensation vote (TSV) was slightly lower for the TASD users. This study demonstrates how a personalized conditioning system could be designed and integrated into the existing esthetics of buildings to provide cooling retrofits and potentially save energy. [ABSTRACT FROM AUTHOR]

In the present study, the axial behaviour of lightweight geopolymer concrete-infilled encased circular steel columns (LWGFST) under the effect of fire loading—rapid cooling was investigated. A total of 12 columns (600 mm height and 114 mm outer diameter) were cast. The shapes for encased steel sections adopted were circular, square and I section. Six columns were subjected to axial loading; the remaining six were fire-loaded (ISO834), suddenly cooled, and subjected to compression. Numerical analysis for columns was achieved through ANSYS workbench. The study examined the effect of the cross-section of encased steel, section steel ratio, and sudden cooling on failure pattern, ductility, and load–deflection behaviour. The LWGFST columns with circular and I section as encasement showed enhanced performance even after being subjected to fire loading followed by sudden cooling. Design equations were used to check the strength ratio for columns with I-section encasement, and the predictions corroborated with the experimental values for unaffected columns. In contrast, the predictions underestimated the confinement effect for fire-affected and suddenly cooled columns. [ABSTRACT FROM AUTHOR]

• To improve data center performance, it must be efficiently cooled. • This paper undertakes a detailed examination of the most recent cooling optimization techniques. • Several methods are discussed like regular air conditioning, free cooling, and liquid cooling. • An assessment of overhead and underfloor air delivery technologies is presented. • The effects of baffles, variable airflow control, and server placement are investigated. In order to increase data centers' efficiency and performance, a proper cooling system should be applied. This article provides a comprehensive assessment which explores current cooling optimization technologies for data centers. Standard traditional technologies like air conditioning, free cooling, and liquid cooling are investigated. Their limitations as well as proposed improvements are thoroughly discussed. The article also delves into underfloor and overhead air supply technologies, presenting their advantages and drawbacks. The review introduces novel approaches at the rack level cooling, including baffles, variable airflow management, and optimal server placement. Key findings stress the efficacy of optimized airflow systems and innovative rack-level cooling, underlining their role in reducing energy consumption and enhancing overall performance. Notably, potential energy savings of up to 67.2 % compared to traditional methods are demonstrated. The adoption of advanced cooling technologies, such as direct and indirect natural cooling, liquid-cooling cold plates, submersion, heat pipe, and thermosiphon-based cooling, exhibits promising energy efficiency gains and reduced Power Usage Effectiveness (PUE) values. Research into content-specific efficiency enhancements, adaptable energy-saving tactics, and all-encompassing server power consumption models is necessary. To work toward future sustainable, energy-efficient data centers, researchers should investigate how CRACs and server fans interact, find ways to integrate thermal and power management, and how artificial intelligence can be used to cool servers in an eco-friendly way. [ABSTRACT FROM AUTHOR]

If pure hydrogen is used as a fuel in high-temperature fuel cells, waste heat must be removed by air cooling, which requires increased power consumption for supplying excess air. This study presents a hydrogen-fed solid oxide fuel cell (SOFC) that uses water instead of air for stack cooling and improved system performance. A novel SOFC system with energy cascade utilization is also proposed using cooling water as the working fluid for a steam turbine. Water cooling for the SOFC stack cooling reduced the stack power and efficiency but significantly reduced the power consumption for supplying excess air by more than 60%. Under ambient SOFC operating pressure, the net power and efficiency of the proposed system were increased by 25.6% and 12.2%p compared to the air-cooled system, respectively. At an SOFC operating pressure of 1000 kPa, the proposed hybrid system with energy cascade utilization achieved improvements of 10.2% in net power and 7.5%p in net efficiency, leading to efficiency higher than 73%. This study is significant in that it proposes a novel high-efficiency SOFC system with energy cascade utilization by using two-phase water as a cooling medium and working fluid of steam turbine. [ABSTRACT FROM AUTHOR]

This study aims to verify the effectiveness of the 250 HP class compressor system to which the integrated hybrid air-foil magnetic thrust bearing (i-HFMTB) proposed in (Ha et al., 2023, "Integrated Hybrid Air Foil-Magnetic Thrust Bearing (i-HFMTB) Part I: Preliminary Experimental Test for Rotordynamic Parameter Identification and Behavior With PD Control," ASME Paper No. GT2023-102860) [1] is applied, and the vibration and instability problems of air-foil journal bearing (AFJB) occurring in the rigid mode are controlled by i-HFMTB. The compressor rotor is supported by two AFJB (journal diameter = 60 mm) and an i-HFMTB, and the length and mass of the rotor are 550 mm and 15.24 kg, respectively. i-HFMTB has a structure in which air-foil thrust bearing (AFTB) pads are inserted into eight slotted active magnetic thrust bearings (AMTB), and PD control (proportional gain: 4000; differential gain: 10) is applied. The operating area was identified through AFJB's dynamic coefficients and rotordynamic analysis. As a result, in the experiment with the 250 HP compressor system supported only by two AFJB, sub- and super-synchronous vibrations were generated owing to the AFJB's insufficient load capacity and damping in the rigid mode (7000 rpm) region, and this instability did not disappear even upon increasing the speed to 15,000 rpm. However, when i-HFMTB was turned on in rigid mode, it was confirmed that the sub- and super-synchronous vibrations were significantly reduced. The thrust collar tilt angle was calculated through orbit trajectory analysis of the impeller and cooling side, and it was confirmed that the tilt angle of the thrust collar was reduced during i-HFMTB operation. [ABSTRACT FROM AUTHOR]

Highlights: Engineering MXene into electrospun nanofibers can effectively enhance its thermal emissivity and conductance, and the unidirectional water transport of the wettability-gradient-induced-diode (WGID) membrane displayed diode-like properties with wettability gradient by tailoring the water contact angle of each single layer. The WGID membrane could achieve a cooling temperature of 1.5 °C in the "dry" state, and 7.1 °C in the "wet" state, with high emissivity of 96.40% in the MIR range, superior thermal conductivity of 0.3349 W m−1 K−1. Zero-energy-consumption for personal cooling management via multiple heat dissipation pathways, including thermal radiation, conduction, and evaporation. Thermoregulatory textiles, leveraging high-emissivity structural materials, have arisen as a promising candidate for personal cooling management; however, their advancement has been hindered by the underperformed water moisture transportation capacity, which impacts on their thermophysiological comfort. Herein, we designed a wettability-gradient-induced-diode (WGID) membrane achieving by MXene-engineered electrospun technology, which could facilitate heat dissipation and moisture-wicking transportation. As a result, the obtained WGID membrane could obtain a cooling temperature of 1.5 °C in the "dry" state, and 7.1 °C in the "wet" state, which was ascribed to its high emissivity of 96.40% in the MIR range, superior thermal conductivity of 0.3349 W m−1 K−1 (based on radiation- and conduction-controlled mechanisms), and unidirectional moisture transportation property. The proposed design offers an approach for meticulously engineering electrospun membranes with enhanced heat dissipation and moisture transportation, thereby paving the way for developing more efficient and comfortable thermoregulatory textiles in a high-humidity microenvironment. [ABSTRACT FROM AUTHOR]

Highlights: A lamellar-structured fluorinated cellulose nanofiber aerogel film is prepared by filtration-induced delaminated gelation and ambient drying. The aerogel film demonstrates exceptional mechanical flexibility and resistance to complex deformations. The aerogel film displays low thermal conductivity, high visible-light transmittance and superior selective infrared emissivity, rendering it high solar-thermal regulatory cooling performance. The demand for highly porous yet transparent aerogels with mechanical flexibility and solar-thermal dual-regulation for energy-saving windows is significant but challenging. Herein, a delaminated aerogel film (DAF) is fabricated through filtration-induced delaminated gelation and ambient drying. The delaminated gelation process involves the assembly of fluorinated cellulose nanofiber (FCNF) at the solid–liquid interface between the filter and the filtrate during filtration, resulting in the formation of lamellar FCNF hydrogels with strong intra-plane and weak interlayer hydrogen bonding. By exchanging the solvents from water to hexane, the hydrogen bonding in the FCNF hydrogel is further enhanced, enabling the formation of the DAF with intra-layer mesopores upon ambient drying. The resulting aerogel film is lightweight and ultra-flexible, which possesses desirable properties of high visible-light transmittance (91.0%), low thermal conductivity (33 mW m−1 K−1), and high atmospheric-window emissivity (90.1%). Furthermore, the DAF exhibits reduced surface energy and exceptional hydrophobicity due to the presence of fluorine-containing groups, enhancing its durability and UV resistance. Consequently, the DAF has demonstrated its potential as solar-thermal regulatory cooling window materials capable of simultaneously providing indoor lighting, thermal insulation, and daytime radiative cooling under direct sunlight. Significantly, the enclosed space protected by the DAF exhibits a temperature reduction of 2.6 °C compared to that shielded by conventional architectural glass. [ABSTRACT FROM AUTHOR]

Evaporative cooling stands as the prevailing method for achieving ultracold temperatures in atomic systems. Current schemes of evaporation selectively remove the hotter atoms near the edge of the trap, as the hotter and colder atoms are distributed in different spatial regions of the trapping potential. However, a long-standing goal is to directly remove the higher momentum atoms, irrespective of their spatial distribution. For this purpose, we demonstrate collisional cooling for a 6Li Fermi gas through inelastic three-body recombination near a narrow Feshbach resonance. Such three-body recombination can induce either heating or cooling effects, and the decay of the quasi-bound Feshbach molecule stirs the hotter atoms away from the trapping potential. When the threshold energy of the Feshbach molecule exceeds the atom's average kinetic energy of 3/2kBT, the cooling effect becomes more pronounced. Finally, we observe strong temperature dependence in this collisional cooling process, with greater efficiency achieved at lower temperatures. Evaporative cooling is the prevailing method for achieving ultracold temperatures in atomic systems, but the schemes to remove hotter atoms are limited by the spatial profile of the trapping potential. To overcome this limitation, the authors demonstrate a three-body recombination-based collisional cooling scheme for selective removal of hotter atoms. [ABSTRACT FROM AUTHOR]

In order to understand the energy-saving system of building cooling and heating integration, the author proposes a research on an energy-saving system of building cooling and heating integration based on building information modelling (BIM) technology. The author first analyzed the energy-saving performance of the system by establishing models for each module based on meteorological data simulated on the DeST software platform. Secondly, in order to analyze the energy consumption of the integrated system, it is necessary to establish a residential building model, and select the building model in the cold winter and hot summer areas of a city for analysis. The results show that due to the system's heat storage function, there is no need to consume electricity in spring and autumn. Compared to the electric heating hot water mode, the integrated system can save 1198.85 kWh of electricity in non-cooling and heating seasons, with a 100% energy-saving rate. Compared to not using an integrated system, it can achieve an energy-saving rate of 81.9% throughout the entire refrigeration and heating season, with significant energy-saving effects. The integrated heating, cooling and hot water system of BIM technology adopts the technology of cool storage and heat storage coupled with solar energy and heat pump technology. The system has simple structure, obvious energy-saving effect, good environmental protection, and can adapt to various climates throughout the year. The introduction of underfloor heating also increases the comfort of buildings and residences. [ABSTRACT FROM AUTHOR]

Current work delves into enhancing the productivity of a photovoltaic (PV) unit by incorporating a thermoelectric generator (TEG). The cooling mechanism employs a triangular-shaped duct with a ferrofluid, and magnetic force is employed to augment the cooling efficiency. Additionally, the model accounts for the impact of dust on the system's productivity. The efficiency components, namely ηth (thermal), ηTE (thermoelectric), and ηPV (electrical PV), have been evaluated across different ranges of ϕ (nanoparticle concentration), Ha (Hartmann number), and Vin (inlet velocity). These results have been obtained through rigorous numerical simulations, with a comprehensive validation test to ensure their accuracy and reliability. When accounting for the presence of dust particles, we observe a reduction in ηth, ηTE, and ηPV by approximately 3.98, 6.96, and 9.46%, respectively. Conversely, in the presence of dust, as Ha is increased, we note a notable enhancement in ηth, ηTE, and ηPV, showing an increase of around 6.68, 19.16, and 0.69% respectively. It is worth mentioning that the increase in ηPV's enhancement diminishes by about 4.12% under the influence of dust. When Vin is set at 0.078, we observe significant enhancements in ηth, ηTE, and ηPV, amounting to approximately 7.29, 20.25, and 0.72%, respectively, as Ha increases. However, it is worth noting that the influence of Ha on both ηth and ηTE diminishes, showing a decrease of about 8.25 and 4.48%, respectively, when Vin is set to 0.17 m/s. On the other hand, an increase in Vin leads to an intensified effect on ηth, ηTE, and ηPV, with enhancements of around 10.19, 29.14, and 1%, respectively, under the condition of Ha = 0. Furthermore, with the rise of Ha, the influence of Vin on ηPV experiences an increment of about 0.5%, while its impact on ηth diminishes by approximately 6%. Introducing nanoparticles can bolster the thermal characteristics of the ferrofluid, leading to significant enhancements in performance, particularly in ηTE. However, it is worth noting that the improvements in ηth, ηTE, and ηPV due to the addition of nanoparticles decrease by about 13.37, 9.91, and 4.78%, respectively, with the increase of Vin, especially in the absence of Ha. Additionally, the uniformity experiences substantial improvements of approximately 22.54 and 31.25% with the augmentation of Ha, observed at Vin values of 0.078 and 0.17, respectively. [ABSTRACT FROM AUTHOR]

Low-mass planets migrate in the type-I regime. In the inviscid limit, the contrast between the vortensity trapped inside the planet's corotating region and the background disc vortensity leads to a dynamical corotation torque, which is thought to slow down inward migration. We investigate the effect of radiative cooling on low-mass planet migration using inviscid 2D hydrodynamical simulations. We find that cooling induces a baroclinic forcing on material U-turning near the planet, resulting in vortensity growth in the corotating region, which in turn weakens the dynamical corotation torque and leads to 2–3× faster inward migration. This mechanism is most efficient when cooling acts on a time-scale similar to the U-turn time of material inside the corotating region, but is none the less relevant for a substantial radial range in a typical disc (R ∼ 5–50 au). As the planet migrates inwards, the contrast between the vortensity inside and outside the corotating region increases and partially regulates the effect of baroclinic forcing. As a secondary effect, we show that radiative damping can further weaken the vortensity barrier created by the planet's spiral shocks, supporting inward migration. Finally, we highlight that a self-consistent treatment of radiative diffusion as opposed to local cooling is critical in order to avoid overestimating the vortensity growth and the resulting migration rate. [ABSTRACT FROM AUTHOR]

In this study, the whisker structure of a harbor seal is applied to the lip and the trailing edge of a turbine cooling blade with a pressure-side cutback. Four cases are studied in this article, including a prototype, a whisker trailing edge, a PP (The lip's peak and the trailing edge's peak are designed at the same blade height) case, and a PV (The lip's peak and the trailing edge's valley are designed at the same blade height) case. The DDES method is used to simulate the flow and thermal mixing process in the cascade. The coolant mass flow ratios ( c m ) of 0.5% and 1% at an outlet Mach number of 0.9 are simulated. The PP case can achieve the best aerodynamic performance, which reduces the thermodynamic energy loss coefficient of the prototype by 0.98% and 0.99% at c m = 0.5% and c m = 1%, respectively. The PP case and the PV case increase the lowest spanwise average adiabatic film cooling effectiveness on the cutback surface from 0.5 to 0.7 at c m = 0.5%. The film cooling effectiveness of the PP case and the PV case can remain close to 1 over the entire cutback surface at c m = 1%. The PP case transforms the trailing edge shedding vortices on the pressure side into hairpin vortices. The whisker lip suppresses the lip vortex and alters the closed separation bubble on the cutback surface, causing the coolant to converge toward Section 1. The convergence of coolant is more helpful for the PP case to control the pressure side shedding vortex, resulting in a lower thermodynamic energy loss. [ABSTRACT FROM AUTHOR]

Highlights: This review delves into the intricate relationship between thermal models, function-oriented design principles, and practical applications in personal radiative thermal management (PRTM). It provides an in-depth discussion on design strategies for radiative cooling, heating, and dual-mode modulating textiles, offering practical insights for application. It offers a thorough examination of the prospects and challenges of PRTM textiles, proposing potential solutions and future directions for the field. Maintaining thermal comfort within the human body is crucial for optimal health and overall well-being. By merely broadening the set-point of indoor temperatures, we could significantly slash energy usage in building heating, ventilation, and air-conditioning systems. In recent years, there has been a surge in advancements in personal thermal management (PTM), aiming to regulate heat and moisture transfer within our immediate surroundings, clothing, and skin. The advent of PTM is driven by the rapid development in nano/micro-materials and energy science and engineering. An emerging research area in PTM is personal radiative thermal management (PRTM), which demonstrates immense potential with its high radiative heat transfer efficiency and ease of regulation. However, it is less taken into account in traditional textiles, and there currently lies a gap in our knowledge and understanding of PRTM. In this review, we aim to present a thorough analysis of advanced textile materials and technologies for PRTM. Specifically, we will introduce and discuss the underlying radiation heat transfer mechanisms, fabrication methods of textiles, and various indoor/outdoor applications in light of their different regulation functionalities, including radiative cooling, radiative heating, and dual-mode thermoregulation. Furthermore, we will shine a light on the current hurdles, propose potential strategies, and delve into future technology trends for PRTM with an emphasis on functionalities and applications. [ABSTRACT FROM AUTHOR]