Facial recognition payment(FRP),a new method of contactless payment,has attracted considerable attention over the past few years.However,the research on this topic remains nascent.This study assessed the drivers of cu...Facial recognition payment(FRP),a new method of contactless payment,has attracted considerable attention over the past few years.However,the research on this topic remains nascent.This study assessed the drivers of customers’FRP continuance intention from the perspectives of coolness and inspiration.We use online survey data from 610 Chinese FRP customers as the basis for our conceptual model.The results show that the coolness factors of subculture,attractiveness,utility,and originality have positive and significant effects on customers’inspired-by states and that subculture and utility also promote inspired-to.Inspired-by is positively associated with inspiredto,which in turn enhances customers’FRP continuance intention.Furthermore,the relationship between inspired-to and FRP continuance intention is negatively moderated by financial risk.In addition to contributing to the literature on FRP,coolness,and customer inspiration,this study offers several suggestions for implementing and developing FRP systems.展开更多
By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,t...By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.展开更多
In this study,a Gaussian Process Regression(GPR)surrogate model coupled with a Bayesian optimization algorithm was employed for the single-objective design optimization of fan-shaped film cooling holes on a concave wa...In this study,a Gaussian Process Regression(GPR)surrogate model coupled with a Bayesian optimization algorithm was employed for the single-objective design optimization of fan-shaped film cooling holes on a concave wall.Fan-shaped holes,commonly used in gas turbines and aerospace applications,flare toward the exit to form a protective cooling film over hot surfaces,enhancing thermal protection compared to cylindrical holes.An initial hole configuration was used to improve adiabatic cooling efficiency.Design variables included the hole injection angle,forward expansion angle,lateral expansion angle,and aperture ratio,while the objective function was the average adiabatic cooling efficiency of the concave wall surface.Optimization was performed at two representative blowing ratios,M=1.0 and M=1.5,using the GPR-based surrogate model to accelerate exploration,with the Bayesian algorithm identifying optimal configurations.Results indicate that the optimized fan-shaped holes increased cooling efficiency by 15.2%and 12.3%at low and high blowing ratios,respectively.Analysis of flow and thermal fields further revealed how the optimized geometry influenced coolant distribution and heat transfer,providing insight into the mechanisms driving the improved cooling performance.展开更多
Methods allowing passive daytime radiative cooling(PDRC)to be carried out in an energy-efficient and scalable way are potentially important for various disciplines.Here,we report a sustainable strategy for scalable-de...Methods allowing passive daytime radiative cooling(PDRC)to be carried out in an energy-efficient and scalable way are potentially important for various disciplines.Here,we report a sustainable strategy for scalable-designed and color-regulating PDRC coating based on high-crystallinity photonic metamaterial(crystallinity:71.5%;enhanced assembly efficiency:72%),that is derived from the as-prepared 55 wt%solid content poly(methyl methacrylate-butyl acrylate-methacrylic acid)P(MMA-BA-MAA)monodispersed latexes(approaching theoretical limit:59 wt%).Robust meter-scale PDRC coatings are constructed by various industrial modes onto diverse surfaces,addressing bottlenecks like dull appearance,high cost,low efficiency,and hard construction.Notably,the solar reflectance,long-wave infrared emittance,and calculated theoretical cooling power of the designed PDRC coating,respectively,reach~0.94,~0.97,and~95.5 W m^(-2)under solar radiation,which can achieve an average 5.3℃ sub-ambient daytime temperature drop in the summer in Nanjing.The cooling performance,scale preparation,and cost-effectiveness of the PDRC coating have extended into leading position compared with those of state-of-the-art designs.This work provides promising route to reduce carbon emissions and energy consumption for global sustainability.展开更多
The optical tweezer experiment with neutral atoms is widely used for quantum information research.Here,we present a compact dual magneto-optical trap(MOT)setup for a two-species optical tweezer.Rubidium(Rb)atoms are d...The optical tweezer experiment with neutral atoms is widely used for quantum information research.Here,we present a compact dual magneto-optical trap(MOT)setup for a two-species optical tweezer.Rubidium(Rb)atoms are directly captured using a vapor MOT,while potassium(K)atoms are collected via a 2-stage MOT.Both the quadratic and gradient magnetic fields required for the MOT and Zeeman slower are created by permanent magnets.With the help of the Zeeman slower,the K MOT loading efficiency is enhanced by a factor of three.After the MOT stage,we apply D_(1) gray molasses to reduce the temperature of the K atoms to 9μK.Using this apparatus,both Rb and K are loaded into the optical tweezer.展开更多
Radiative cooling textiles with spectrally selective surfaces offer a promising energy-efficient approach for sub-ambient cooling of outdoor objects and individuals.However,the spectrally selective mid-infrared emissi...Radiative cooling textiles with spectrally selective surfaces offer a promising energy-efficient approach for sub-ambient cooling of outdoor objects and individuals.However,the spectrally selective mid-infrared emission of these textiles significantly hinders their efficient radiative heat exchange with self-heated objects,thereby posing a significant challenge to their versatile cooling applicability.Herein,we present a bicomponent blow spinning strategy for the production of scalable,ultra-flexible,and healable textiles featuring a tailored dual gradient in both chemical composition and fiber diameter.The gradient in the fiber diameter of this textile introduces a hierarchically porous structure across the sunlight incident area,thereby achieving a competitive solar reflectivity of 98.7%on its outer surface.Additionally,the gradient in the chemical composition of this textile contributes to the formation of Janus infrared-absorbing surfaces:The outer surface demonstrates a high mid-infrared emission,whereas the inner surface shows a broad infrared absorptivity,facilitating radiative heat exchange with underlying self-heated objects.Consequently,this textile demonstrates multi-scenario radiative cooling capabilities,enabling versatile outdoor cooling for unheated objects by 7.8℃ and self-heated objects by 13.6℃,compared to commercial sunshade fabrics.展开更多
Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strate...Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strategy.With the continuous development of radiative cooling technologies,the material selection,preparation process,structural design,and applica-tion fields have also made more diverse progress.Therefore,this review aims to systematically introduce the fundamental concepts and underlying principles of radiative cooling.A summary of the commonly used materials for radiative cooling is provided.In addition,the advanced fabrication processes and structural designs of radiative cooling materials are further explored and discussed.Subsequently,the unique functions of radiative cooling materials are highlighted to enhance their applicability and usefulness across various fields.An overview of combining radiative cooling materials with different fields is also provided.In reality,these applications hold the potential to improve thermal management across a range of fields.Finally,it summarizes the shortcomings and great potential of radiative cooling materials in various fields.It also looks forward to the future,aiming to promote the progress and widespread adoption of radiative cooling technologies.展开更多
The high-alloyed wrought superalloy GH4975 tends to form coarse MC carbides and eutectic(γ+γ′)phases,which adversely affect the cogging and homogenization process.To provide theoretical guidance for control of MC c...The high-alloyed wrought superalloy GH4975 tends to form coarse MC carbides and eutectic(γ+γ′)phases,which adversely affect the cogging and homogenization process.To provide theoretical guidance for control of MC carbides and eutectic(γ+γ′)formation,differential thermal analysis(DTA)was utilized to investigate the effect of cooing rate(10-90℃·min^(-1))on solidification behavior and micro-segregation of GH4975 alloy.According to the thermodynamic calculation and distribution characteristics of precipitates,the MC carbides can act as nucleation sites forγdendrites,but the nucleation ofγdendrites becomes less dependent on the MC carbide primers at higher cooling rates.As theγdendrites grow,the elements including Ti and Nb gradually accumulate in the residual liquid and leads to the formation of more MC carbides near the interdendritic region.Finally,the solidification is terminated with the formation of eutectic(γ+γ′).With an increase in cooling rate,the liquidus temperature rises,but the solidus temperature decreases,and thus the solidification range is obviously enlarged.The dendritic structure is significantly refined by the increase of cooling rate.The secondary dendrite arm spacing,λ_(2),as a function of cooling rate,T,can be expressed asλ_(2)=216.78T^(-0.42).Moreover,the increasing cooling rate weakens the back diffusion of Al,Ti,and Nb,increases the undercooling,and limits the growth of precipitates.Consequently,the sizes of MC carbides,eutectic(γ+γ′),and primaryγ′significantly decrease,but the area fraction of eutectic(γ+γ′)linerly increases as the cooling rate rises.Thus moderate cooling rate(such as 30℃·min^(-1))should be selected during the solidification process of GH4975 alloy.展开更多
The influences of silicon addition to commercially pure magnesium(CP Mg)and cooling rate during solidification on the as-cast microstructure and shear mechanical properties of Mg-Si alloys were systematically investig...The influences of silicon addition to commercially pure magnesium(CP Mg)and cooling rate during solidification on the as-cast microstructure and shear mechanical properties of Mg-Si alloys were systematically investigated.For this purpose,the Mg-0.6Si,Mg-1.34Si,and Mg-3Si(wt%)alloys were considered as hypoeutectic,eutectic,and hypereutectic alloys,respectively.By decreasing the geometrical modulus of the solidifying section(increasing cooling rate),remarkable grain refinement,refining the dendrite arm spacing(DAS),and modification of Mg_(2)Si particles were achieved.Moreover,the grain size was refined via Si addition in the hypoeutectic range,while coarsening of grain size at high Si concentrations was observed.The results of shear punch testing and hardness measurements demonstrated that the ultimate shear strength(USS)and hardness increased by increasing the cooling rate during solidification.Moreover,Si addition generally improved hardness,while the highest USS level was achieved for the eutectic alloy due to the fine grain size and strengthening effect of the eutectic constituent.However,regarding the hypereutectic Mg-3Si alloy that exhibited high hardness,the shear properties were inferior due to the detrimental effect of the primary Mg_(2)Si particles.Finally,the results were discussed with consideration of the relationship between strength and hardness,for which the critical effect of Si was clarified.展开更多
Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for...Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for mitigating the energy crisis.A comprehensive review connecting the advancements in engineered radiative cooling systems(ERCSs),encompassing material and structural design as well as thermal and energy-related applications,is currently absent.Herein,this review begins with a concise summary of the essential concepts of ERCSs,followed by an introduction to engineered materials and structures,containing nature-inspired designs,chromatic materials,meta-structural configurations,and multilayered constructions.It subsequently encapsulates the primary applications,including thermal-regulating textiles and energy-saving devices.Next,it highlights the challenges of ERCSs,including maximized thermoregulatory effects,environmental adaptability,scalability and sustainability,and interdisciplinary integration.It seeks to offer direction for forthcoming fundamental research and industrial advancement of radiative cooling systems in real-world applications.展开更多
The electrocaloric(EC)effect refers to the change in the polarization entropy and/or temperature of dielectric materials when an electric field is applied and removed.EC refrigeration has received increasing interest ...The electrocaloric(EC)effect refers to the change in the polarization entropy and/or temperature of dielectric materials when an electric field is applied and removed.EC refrigeration has received increasing interest as an alternative to conventional refrigeration technologies because it provides both high energy efficiency and zero global warming potential.In this review,we first introduce the thermodynamic fundamentals of the EC effect and the mechanism of EC refrigeration cycles.We then present recent advances in EC cooling technologies,from material improvements to device demonstrations,including a critical analysis of existing material and device characterization methodologies and a discussion of how to reliably measure the parameters of materials and devices.Finally,the current challenges and possible future prospects for EC cooling technology are outlined.展开更多
With the rapid growth of cloud computing,the number of data centers(DCs)continuously increases,leading to a high-energy consumption dilemma.Cooling,apart from IT equipment,represents the largest energy consumption in ...With the rapid growth of cloud computing,the number of data centers(DCs)continuously increases,leading to a high-energy consumption dilemma.Cooling,apart from IT equipment,represents the largest energy consumption in DCs.Passive design(PD)and active design(AD)are two important approaches in architectural design to reduce energy consumption.However,for DC cooling,few studies have summarized AD,and there are almost no studies on PD.Based on existing international research(2005-2024),this paper summarizes the current state of cooling strategies for DCs.PD encompasses floors,ceilings,and layout and zoning of racks.Additionally,other passive strategies not yet studied in DCs are critically examined.AD includes air,liquid,free,and two-phase cooling.This paper systematically compares the performance of different AD technologies on various KPIs,including energy,economic,and environmental indicators.This paper also explores the application of different cooling design strategies through best-practice examples and presents advanced algorithms for energy management in operational DCs.This study reveals that free cooling is widely employed,with Artificial Neural Networks emerging as the most popular algorithm for managing cooling energy.Finally,this paper suggests four future directions for reducing cooling energy in DCs,with a focus on the development of passive strategies.This paper provides an overview and guide to DC energy-consumption issues,emphasizes the importance of implementing passive and active design strategies to reduce DC cooling energy consumption,and provides directions and references for future energy-efficient DC designs.展开更多
During geothermal resource exploitation,the potential deterioration of mechanical properties in high-temperature granite subjected to cooling poses a significant safety concern.To address this,the present study invest...During geothermal resource exploitation,the potential deterioration of mechanical properties in high-temperature granite subjected to cooling poses a significant safety concern.To address this,the present study investigates the coupled thermo-mechanical behavior of granite during heating and cooling through a combination of laboratory tests and finite difference method analysis.Initial investigations involve X-ray diffraction,thermal expansion test,thermogravimetric analysis,and uniaxial compression test.Results show the significant variations of granite properties under different thermal conditions,attributed to temperature gradients,water evaporation,and mineral phase transitions.Subsequently,a model considering temperature-dependent parameters and real-time cooling rates was employed to simulate linear heating and nonlinear cooling processes.Simulation results indicate that the thermal cracking predominantly occurs during the heating stage,with tensile failure as the primary mode.Additionally,a faster real-time cooling rate at higher temperatures intensifies the thermal cracking behavior in granite.This study effectively elucidates the thermomechanical coupling behavior of granite during heating and cooling processes,providing insights into the mechanisms of mechanical property changes with rising or decreasing temperatures.展开更多
The promising prospects for all-day building thermal management are driving widespread research into spectrally selective manipulation materials.This article first summarizes the evolution path of metal reversible dep...The promising prospects for all-day building thermal management are driving widespread research into spectrally selective manipulation materials.This article first summarizes the evolution path of metal reversible deposition technology,noting its advantages of cost-effectiveness and scientific rigor.It then highlights the groundbreaking work by Wang et al.(published in ACS Energy Letters,2025,10,3231)on coupling metastructured photothermal conversion electrodes and reversible Cu deposition for all-day energy management.Finally,the commercial viability of Wang et al.'s approach for building energy saving and its potential applicability to other scenarios are elaborated.展开更多
We propose a novel cooling protocol within a triple-Laguerre-Gaussian cavity optomechanical system,which is designed to suppress the thermal vibrations of a rotating mirror to reach its quantum ground state.The system...We propose a novel cooling protocol within a triple-Laguerre-Gaussian cavity optomechanical system,which is designed to suppress the thermal vibrations of a rotating mirror to reach its quantum ground state.The system incorporates two auxiliary cavities and an atomic ensemble coupled to a Laguerre-Gaussian rotational cavity.By carefully selecting system parameters,the cooling process of the rotating mirror is significantly enhanced,while the heating process is effectively suppressed,enabling efficient ground-state cooling even in the unresolved sideband regime.Compared to previous works,our scheme reduces the stringent restrictions on auxiliary systems,making it more experimentally feasible under broader parameter conditions.These findings provide a robust approach for achieving ground-state cooling in mechanical resonators.展开更多
As an emerging thermal management strategy,dynamic radiative cooling(DRC)technology enables dynamic modulation of spectral radiation properties under varying environmental conditions through the directional design of ...As an emerging thermal management strategy,dynamic radiative cooling(DRC)technology enables dynamic modulation of spectral radiation properties under varying environmental conditions through the directional design of material spectral characteristics.However,a comprehensive review of the basic physical mechanisms of radiative heat transfer in DRC materials and various design principles involved in dynamic radiative thermal regulation is still lacking.This review systematically summarizes recent advances in this field,spanning from fundamental physical principles to intrinsic molecular and electronic mechanisms,and further to representative material systems and multi-band regulation strategies,highlighting the interdisciplinary research achievements and technological innovations.This work outlines the core mechanisms governing the regulation of different spectral bands during radiative heat transfer processes.Then,the main categories of DRC materials are systematically reviewed,including actively responsive structures,passively responsive structures,and multi-stimuli-responsive materials.Furthermore,the challenges faced by current DRC technology and future development trends are summarized and discussed,providing valuable reference and guidance for further research in this field.Although DRC technologies still face significant challenges in material stability,manufacturing processes,and system integration,the continuous advances in related areas and multifunctional materials are expected to broaden the application prospects of DRC in the future.展开更多
Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics...Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.展开更多
This article presents an adaptive intelligent control strategy applied to a lumped-parameter evaporator model,i.e.,a simplified dynamic representation treating the evaporator as a single thermal node with uniform temp...This article presents an adaptive intelligent control strategy applied to a lumped-parameter evaporator model,i.e.,a simplified dynamic representation treating the evaporator as a single thermal node with uniform temperature distribution,suitable for control design due to its balance between physical fidelity and computational simplicity.The controller uses a wavelet-based neural proportional,integral,derivative(PID)controller with IIR filtering(infinite impulse response).The dynamic model captures the essential heat and mass transfer phenomena through a nonlinear energy balance,where the cooling capacity“Qevap”is expressed as a non-linear function of the compressor frequency and the temperature difference,specifically,Q_(evap)=k_(1)u(T_(in)−T_(e))with u as compressor frequency,Te evaporator temperature,and Tin inlet fluid temperature.The operating conditions of the system,in general terms,focus on the following variables,the overall thermal capacity is 1000 J/K,typical for small-capacity heat exchangers,The mass flow is 0.05 kg/s,typical for secondary liquid cooling circuits,the overall loss coefficient of 50 W/K that corresponds to small evaporators with partial insulation,the temperatures(inlet)of 10℃and the temperature of environment of 25℃,thermal load of 200 W that corresponds to a small-scaled air conditioning applications.To handle system nonlinearities and improve control performance,aMorlet wavelet-based neural network(Wavenet)is used to dynamically adjust the PID gains online.An IIR filter is incorporated to smooth the adaptive gains,improving stability and reducing oscillations.In contrast to prior wavelet-or neural-adaptive PID controllers in HVAC applications,which typically adjust gains without explicit filtering or not tailored to evaporator dynamics,this work introduces the first PID–Wavenet scheme augmented with an IIR-based stabilization layer,specifically designed to address the combined challenges of nonlinear evaporator behavior,gain oscillation,and real-time implementability.The proposed controller(PID-Wavenet+IIR)is implemented and validated inMATLAB/Simulink,demonstrating superior performance compared to a conventional PID tuned using Simulink’s auto-tuning function.Key results include a reduction in settling time from 13.3 to 8.2 s,a reduction in overshoot from 3.5%to 0.8%,a reduction in steady-state error from 0.12℃ to 0.02℃and a 13%reduction in energy overall consumption.The controller also exhibits greater robustness and adaptability under varying thermal loads.This explicit integration of wavelet-driven adaptation with IIR-filtered gain shaping constitutes the main methodological contribution and novelty of the work.These findings validate the effectiveness of the wavelet-based adaptive approach for advanced thermal management in refrigeration and HVAC systems,with potential applications in controlling variable-speed compressors,liquid chillers,and compact cooling units.展开更多
Governed by the second law of thermodynamics,waste heat generation is inevitable and has been a major source of energy loss and environmental concern in human society.Harvesting waste heat into useful energy has thus ...Governed by the second law of thermodynamics,waste heat generation is inevitable and has been a major source of energy loss and environmental concern in human society.Harvesting waste heat into useful energy has thus become a paramount priority,but has remained challenging with efficiency and cost constraints.Thermoelectric generators(TEGs),which convert heat into electricity whenever there is a temperature difference,play a crucial role in waste heat harvesting.However,sustaining the temperature difference for uninterrupted and high-power density electricity generation is a major challenge in TEGs to achieve practical applications due to the thermal equilibrium.Here,we demonstrate a diurnal waste heat harvester by integrating a high-power radiative cooling film as the cool end of TEGs to enable a large and continuous temperature difference.Significant voltage increase from 30.0 mV to 65.7 mV was achieved,leading to a dramatic power density enhancement of 4.8 times from 35.2 mW m^(-2)to 168.6 mW m^(-2).In an open zone,an ultra-high power density of 2.76 W m^(-2)was achieved at a heat source temperature of 80°C,exceeding the performance of state-of-the-art radiatively cooled TEGs.More importantly,a portable and foldable thermal energy harvesting prototype composed of 24 TEGs arranged in an array has been constructed.When attached to a hot object(e.g.a car engine hood),it can output 5 V to charge personal electronics(e.g.a cellphone),making it a promising practical device for harvesting waste heat in a wide range of outdoor applications.展开更多
To fulfill diverse performance requirements in various industrial fields,it is essential to precisely control the inclusion characteristics in 316L stainless steel(316L SS),including chemical composition,size,and quan...To fulfill diverse performance requirements in various industrial fields,it is essential to precisely control the inclusion characteristics in 316L stainless steel(316L SS),including chemical composition,size,and quantity and so on,thus ensuring the steel with high cleanliness and quality.Solidification experiments with different cooling methods were conducted using an Al_(2)O_(3)-CaO-SiO_(2)-MgO refining slag system to investigate the influence of cooling methods upon the characteristic variation and growth behavior of inclusions in 316L SS during the solidification process.Thermodynamic mechanisms underlying the inclusion composition transition during the solidification process were revealed,and a kinetic model for the prediction of the solute element segregation and the inclusion growth in the steel was developed and verified.Results indicated that a nonlinear fitting curve equation for the correlation between the average size of inclusions d and the cooling rate R_(c) was obtained,which was:d=3.728·R_(c)^(-0.134).As the cooling rate went down,Al_(2)O_(3) content in the inclusions correspondingly decreased from 69.43 to 30.54 mass%,while the SiO_(2) content increased from 14.75 to 43.8 mass%.The final inclusion size,calculated by the kinetic inclusion growth model,increased from 2.37 to 9.65μm as the cooling rate was reduced from 56.7 to 0.7 K s^(−1),which were in fair agreement with experimental results.展开更多
基金This study was supported by the National Natural Science Foundation of China(72202185,72302145)the Postdoctoral Science Foundation of China(2023M742232)the Innovation Research 2035 Pilot Plan of Southwest University(SWUPilotPlan026).
文摘Facial recognition payment(FRP),a new method of contactless payment,has attracted considerable attention over the past few years.However,the research on this topic remains nascent.This study assessed the drivers of customers’FRP continuance intention from the perspectives of coolness and inspiration.We use online survey data from 610 Chinese FRP customers as the basis for our conceptual model.The results show that the coolness factors of subculture,attractiveness,utility,and originality have positive and significant effects on customers’inspired-by states and that subculture and utility also promote inspired-to.Inspired-by is positively associated with inspiredto,which in turn enhances customers’FRP continuance intention.Furthermore,the relationship between inspired-to and FRP continuance intention is negatively moderated by financial risk.In addition to contributing to the literature on FRP,coolness,and customer inspiration,this study offers several suggestions for implementing and developing FRP systems.
基金financially supported by the Science and Technology Innovation Program of Hunan Province(2024RC3003)the Central South University Innovation-Driven Research Programme(2023CXQD012)the Initiative for Sustainable Energy for its financial support。
文摘By combining the merits of radiative cooling(RC)and evaporation cooling(EC),radiative coupled evaporative cooling(REC)has attracted considerable attention for sub-ambient cooling purposes.However,for outdoor devices,the interior heating power would increase the working temperature and fire risk,which would suppress their above-ambient heat dissipation capabilities and passive water cycle properties.In this work,we introduced a REC design based on an all-in-one photonic hydrogel for above-ambient heat dissipation and flame retardancy.Unlike conventional design RC film for heat dissipation with limited cooling power and fire risk,REC hydrogel can greatly improve the heat dissipation performance in the daytime with a high workload,indicating a 12.0℃lower temperature than the RC film under the same conditions in the outdoor experiment.In the nighttime with a low workload,RC-assisted adsorption can improve atmospheric water harvesting to ensure EC in the daytime.In addition,our REC hydrogel significantly enhanced flame retardancy by absorbing heat without a corresponding temperature rise,thus mitigating fire risks.Thus,our design shows a promising solution for the thermal management of outdoor devices,delivering outstanding performance in both heat dissipation and flame retardancy.
基金supported by the Jiangsu Association for Science and Technology,grant number SKX 0225089the National Natural Science Foundation of China,grant number 52476027.
文摘In this study,a Gaussian Process Regression(GPR)surrogate model coupled with a Bayesian optimization algorithm was employed for the single-objective design optimization of fan-shaped film cooling holes on a concave wall.Fan-shaped holes,commonly used in gas turbines and aerospace applications,flare toward the exit to form a protective cooling film over hot surfaces,enhancing thermal protection compared to cylindrical holes.An initial hole configuration was used to improve adiabatic cooling efficiency.Design variables included the hole injection angle,forward expansion angle,lateral expansion angle,and aperture ratio,while the objective function was the average adiabatic cooling efficiency of the concave wall surface.Optimization was performed at two representative blowing ratios,M=1.0 and M=1.5,using the GPR-based surrogate model to accelerate exploration,with the Bayesian algorithm identifying optimal configurations.Results indicate that the optimized fan-shaped holes increased cooling efficiency by 15.2%and 12.3%at low and high blowing ratios,respectively.Analysis of flow and thermal fields further revealed how the optimized geometry influenced coolant distribution and heat transfer,providing insight into the mechanisms driving the improved cooling performance.
基金support of the National Natural Science Foundation of China(grant 22508184 to X.Q.Y.,grant 21736006 to S.C.,and grant 22278225 to S.C.)supported by the Natural Funding Program of Jiangsu Province(grant BK20250610 to X.Q.Y.).
文摘Methods allowing passive daytime radiative cooling(PDRC)to be carried out in an energy-efficient and scalable way are potentially important for various disciplines.Here,we report a sustainable strategy for scalable-designed and color-regulating PDRC coating based on high-crystallinity photonic metamaterial(crystallinity:71.5%;enhanced assembly efficiency:72%),that is derived from the as-prepared 55 wt%solid content poly(methyl methacrylate-butyl acrylate-methacrylic acid)P(MMA-BA-MAA)monodispersed latexes(approaching theoretical limit:59 wt%).Robust meter-scale PDRC coatings are constructed by various industrial modes onto diverse surfaces,addressing bottlenecks like dull appearance,high cost,low efficiency,and hard construction.Notably,the solar reflectance,long-wave infrared emittance,and calculated theoretical cooling power of the designed PDRC coating,respectively,reach~0.94,~0.97,and~95.5 W m^(-2)under solar radiation,which can achieve an average 5.3℃ sub-ambient daytime temperature drop in the summer in Nanjing.The cooling performance,scale preparation,and cost-effectiveness of the PDRC coating have extended into leading position compared with those of state-of-the-art designs.This work provides promising route to reduce carbon emissions and energy consumption for global sustainability.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2023YFA1406703 and 2022YFA1404203)the National Natural Science Foundation of China(Grant Nos.12425408,U21A20437 and 12074337)+1 种基金the Natural Science Foundation of Zhejiang Province,China(Grant No.LR21A040002)the Fundamental Research Funds for the Central Universities(Grant No.226-2023-00131)。
文摘The optical tweezer experiment with neutral atoms is widely used for quantum information research.Here,we present a compact dual magneto-optical trap(MOT)setup for a two-species optical tweezer.Rubidium(Rb)atoms are directly captured using a vapor MOT,while potassium(K)atoms are collected via a 2-stage MOT.Both the quadratic and gradient magnetic fields required for the MOT and Zeeman slower are created by permanent magnets.With the help of the Zeeman slower,the K MOT loading efficiency is enhanced by a factor of three.After the MOT stage,we apply D_(1) gray molasses to reduce the temperature of the K atoms to 9μK.Using this apparatus,both Rb and K are loaded into the optical tweezer.
基金financial support from the National Natural Science Foundation of China(Grant No.52273067,52233006)the Fundamental Research Funds for the Central Universities(Grant No.2232023A-03)+3 种基金the Shuguang Program of Shanghai Education Development Foundation and Shanghai Municipal Education Commission(Grant No.23SG29)the Natural Science Foundation of Shanghai(Grant No.24ZR1402400)the Shanghai Scientific and Technological Innovation Project(Grant No.24520713000)Innovation Program of Shanghai Municipal Education Commission(Grant No.2021-01-07-00-03-E00108).
文摘Radiative cooling textiles with spectrally selective surfaces offer a promising energy-efficient approach for sub-ambient cooling of outdoor objects and individuals.However,the spectrally selective mid-infrared emission of these textiles significantly hinders their efficient radiative heat exchange with self-heated objects,thereby posing a significant challenge to their versatile cooling applicability.Herein,we present a bicomponent blow spinning strategy for the production of scalable,ultra-flexible,and healable textiles featuring a tailored dual gradient in both chemical composition and fiber diameter.The gradient in the fiber diameter of this textile introduces a hierarchically porous structure across the sunlight incident area,thereby achieving a competitive solar reflectivity of 98.7%on its outer surface.Additionally,the gradient in the chemical composition of this textile contributes to the formation of Janus infrared-absorbing surfaces:The outer surface demonstrates a high mid-infrared emission,whereas the inner surface shows a broad infrared absorptivity,facilitating radiative heat exchange with underlying self-heated objects.Consequently,this textile demonstrates multi-scenario radiative cooling capabilities,enabling versatile outdoor cooling for unheated objects by 7.8℃ and self-heated objects by 13.6℃,compared to commercial sunshade fabrics.
基金National Natural Science Foundation of China Excellent Youth Fund(No.52222509)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(No.52021003)+3 种基金National Key Research and Development Program of China(No.2018YFA0703300)National Natural Science Foundation of China(No.52105298)Science and Technology Development Program of Jilin Province(No.SKL202402005)"Fundamental Research Funds for the Central Universities".
文摘Radiative cooling passively emits heat to outer space without energy input,offering promise for energy-efficient thermal management.It is an important solution to promote the low-carbon environmental protection strategy.With the continuous development of radiative cooling technologies,the material selection,preparation process,structural design,and applica-tion fields have also made more diverse progress.Therefore,this review aims to systematically introduce the fundamental concepts and underlying principles of radiative cooling.A summary of the commonly used materials for radiative cooling is provided.In addition,the advanced fabrication processes and structural designs of radiative cooling materials are further explored and discussed.Subsequently,the unique functions of radiative cooling materials are highlighted to enhance their applicability and usefulness across various fields.An overview of combining radiative cooling materials with different fields is also provided.In reality,these applications hold the potential to improve thermal management across a range of fields.Finally,it summarizes the shortcomings and great potential of radiative cooling materials in various fields.It also looks forward to the future,aiming to promote the progress and widespread adoption of radiative cooling technologies.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.52474362,52174317 and 51904146)the General Project Funded by Liaoning Province Education Department(Grant No.JYTMS20230943)。
文摘The high-alloyed wrought superalloy GH4975 tends to form coarse MC carbides and eutectic(γ+γ′)phases,which adversely affect the cogging and homogenization process.To provide theoretical guidance for control of MC carbides and eutectic(γ+γ′)formation,differential thermal analysis(DTA)was utilized to investigate the effect of cooing rate(10-90℃·min^(-1))on solidification behavior and micro-segregation of GH4975 alloy.According to the thermodynamic calculation and distribution characteristics of precipitates,the MC carbides can act as nucleation sites forγdendrites,but the nucleation ofγdendrites becomes less dependent on the MC carbide primers at higher cooling rates.As theγdendrites grow,the elements including Ti and Nb gradually accumulate in the residual liquid and leads to the formation of more MC carbides near the interdendritic region.Finally,the solidification is terminated with the formation of eutectic(γ+γ′).With an increase in cooling rate,the liquidus temperature rises,but the solidus temperature decreases,and thus the solidification range is obviously enlarged.The dendritic structure is significantly refined by the increase of cooling rate.The secondary dendrite arm spacing,λ_(2),as a function of cooling rate,T,can be expressed asλ_(2)=216.78T^(-0.42).Moreover,the increasing cooling rate weakens the back diffusion of Al,Ti,and Nb,increases the undercooling,and limits the growth of precipitates.Consequently,the sizes of MC carbides,eutectic(γ+γ′),and primaryγ′significantly decrease,but the area fraction of eutectic(γ+γ′)linerly increases as the cooling rate rises.Thus moderate cooling rate(such as 30℃·min^(-1))should be selected during the solidification process of GH4975 alloy.
文摘The influences of silicon addition to commercially pure magnesium(CP Mg)and cooling rate during solidification on the as-cast microstructure and shear mechanical properties of Mg-Si alloys were systematically investigated.For this purpose,the Mg-0.6Si,Mg-1.34Si,and Mg-3Si(wt%)alloys were considered as hypoeutectic,eutectic,and hypereutectic alloys,respectively.By decreasing the geometrical modulus of the solidifying section(increasing cooling rate),remarkable grain refinement,refining the dendrite arm spacing(DAS),and modification of Mg_(2)Si particles were achieved.Moreover,the grain size was refined via Si addition in the hypoeutectic range,while coarsening of grain size at high Si concentrations was observed.The results of shear punch testing and hardness measurements demonstrated that the ultimate shear strength(USS)and hardness increased by increasing the cooling rate during solidification.Moreover,Si addition generally improved hardness,while the highest USS level was achieved for the eutectic alloy due to the fine grain size and strengthening effect of the eutectic constituent.However,regarding the hypereutectic Mg-3Si alloy that exhibited high hardness,the shear properties were inferior due to the detrimental effect of the primary Mg_(2)Si particles.Finally,the results were discussed with consideration of the relationship between strength and hardness,for which the critical effect of Si was clarified.
基金support from the Contract Research(“Development of Breathable Fabrics with Nano-Electrospun Membrane”,CityU ref.:9231419“Research and application of antibacterial and healing-promoting smart nanofiber dressing for children’s burn wounds”,CityU ref:PJ9240111)+1 种基金the National Natural Science Foundation of China(“Study of Multi-Responsive Shape Memory Polyurethane Nanocomposites Inspired by Natural Fibers”,Grant No.51673162)Startup Grant of CityU(“Laboratory of Wearable Materials for Healthcare”,Grant No.9380116).
文摘Radiative cooling systems(RCSs)possess the distinctive capability to dissipate heat energy via solar and thermal radiation,making them suitable for thermal regulation and energy conservation applications,essential for mitigating the energy crisis.A comprehensive review connecting the advancements in engineered radiative cooling systems(ERCSs),encompassing material and structural design as well as thermal and energy-related applications,is currently absent.Herein,this review begins with a concise summary of the essential concepts of ERCSs,followed by an introduction to engineered materials and structures,containing nature-inspired designs,chromatic materials,meta-structural configurations,and multilayered constructions.It subsequently encapsulates the primary applications,including thermal-regulating textiles and energy-saving devices.Next,it highlights the challenges of ERCSs,including maximized thermoregulatory effects,environmental adaptability,scalability and sustainability,and interdisciplinary integration.It seeks to offer direction for forthcoming fundamental research and industrial advancement of radiative cooling systems in real-world applications.
基金supported by the National Key R&D Program of China(Grant Nos.2020YFA0711500 and 2020YFA0711503)the National Natural Science Foundation of China(Grant Nos.T2488302,T2342010,52076127)+5 种基金the Natural Science Foundation of Shanghai(Grant Nos.20ZR1471700,22JC1401800,and 24Z511405472)the State Key Laboratory of Mechanical System and Vibration(Grant Nos.MSVZD202211,MSVZD202301,and MSVZD202401)Shanghai Jiao Tong University 2030 InitiativeShanghai Jiao Tong University Si Yuan Scholar Programthe Student Innovation Center and the Instrumental Analysis Center at Shanghai Jiao Tong Universitysupport by Shanghai Jiao Tong University 2030 Initiative。
文摘The electrocaloric(EC)effect refers to the change in the polarization entropy and/or temperature of dielectric materials when an electric field is applied and removed.EC refrigeration has received increasing interest as an alternative to conventional refrigeration technologies because it provides both high energy efficiency and zero global warming potential.In this review,we first introduce the thermodynamic fundamentals of the EC effect and the mechanism of EC refrigeration cycles.We then present recent advances in EC cooling technologies,from material improvements to device demonstrations,including a critical analysis of existing material and device characterization methodologies and a discussion of how to reliably measure the parameters of materials and devices.Finally,the current challenges and possible future prospects for EC cooling technology are outlined.
文摘With the rapid growth of cloud computing,the number of data centers(DCs)continuously increases,leading to a high-energy consumption dilemma.Cooling,apart from IT equipment,represents the largest energy consumption in DCs.Passive design(PD)and active design(AD)are two important approaches in architectural design to reduce energy consumption.However,for DC cooling,few studies have summarized AD,and there are almost no studies on PD.Based on existing international research(2005-2024),this paper summarizes the current state of cooling strategies for DCs.PD encompasses floors,ceilings,and layout and zoning of racks.Additionally,other passive strategies not yet studied in DCs are critically examined.AD includes air,liquid,free,and two-phase cooling.This paper systematically compares the performance of different AD technologies on various KPIs,including energy,economic,and environmental indicators.This paper also explores the application of different cooling design strategies through best-practice examples and presents advanced algorithms for energy management in operational DCs.This study reveals that free cooling is widely employed,with Artificial Neural Networks emerging as the most popular algorithm for managing cooling energy.Finally,this paper suggests four future directions for reducing cooling energy in DCs,with a focus on the development of passive strategies.This paper provides an overview and guide to DC energy-consumption issues,emphasizes the importance of implementing passive and active design strategies to reduce DC cooling energy consumption,and provides directions and references for future energy-efficient DC designs.
基金National Natural Science Foundation of China,Grant/Award Number:52104120Hunan Provincial Key Laboratory of Key Technology on Hydropower Development,Grant/Award Number:PKLHD202303。
文摘During geothermal resource exploitation,the potential deterioration of mechanical properties in high-temperature granite subjected to cooling poses a significant safety concern.To address this,the present study investigates the coupled thermo-mechanical behavior of granite during heating and cooling through a combination of laboratory tests and finite difference method analysis.Initial investigations involve X-ray diffraction,thermal expansion test,thermogravimetric analysis,and uniaxial compression test.Results show the significant variations of granite properties under different thermal conditions,attributed to temperature gradients,water evaporation,and mineral phase transitions.Subsequently,a model considering temperature-dependent parameters and real-time cooling rates was employed to simulate linear heating and nonlinear cooling processes.Simulation results indicate that the thermal cracking predominantly occurs during the heating stage,with tensile failure as the primary mode.Additionally,a faster real-time cooling rate at higher temperatures intensifies the thermal cracking behavior in granite.This study effectively elucidates the thermomechanical coupling behavior of granite during heating and cooling processes,providing insights into the mechanisms of mechanical property changes with rising or decreasing temperatures.
基金supported by grants from the National Natural Science Foundation of China(no.62175248,U24A2061)Shanghai Science and Technology Funds(no.23ZR1481900,25ZR1401373)Science Foundation for Youth Scholar of State Key Laboratory of High Performance Ceramics and Superfine Microstructures(no.SKL202202).
文摘The promising prospects for all-day building thermal management are driving widespread research into spectrally selective manipulation materials.This article first summarizes the evolution path of metal reversible deposition technology,noting its advantages of cost-effectiveness and scientific rigor.It then highlights the groundbreaking work by Wang et al.(published in ACS Energy Letters,2025,10,3231)on coupling metastructured photothermal conversion electrodes and reversible Cu deposition for all-day energy management.Finally,the commercial viability of Wang et al.'s approach for building energy saving and its potential applicability to other scenarios are elaborated.
基金Project supported by the National Natural Science Foundation of China(Grant No.62471180)。
文摘We propose a novel cooling protocol within a triple-Laguerre-Gaussian cavity optomechanical system,which is designed to suppress the thermal vibrations of a rotating mirror to reach its quantum ground state.The system incorporates two auxiliary cavities and an atomic ensemble coupled to a Laguerre-Gaussian rotational cavity.By carefully selecting system parameters,the cooling process of the rotating mirror is significantly enhanced,while the heating process is effectively suppressed,enabling efficient ground-state cooling even in the unresolved sideband regime.Compared to previous works,our scheme reduces the stringent restrictions on auxiliary systems,making it more experimentally feasible under broader parameter conditions.These findings provide a robust approach for achieving ground-state cooling in mechanical resonators.
基金supported by the Taishan Scholars of Shandong Province(tsqn202408151)the National Natural Science Foundation of China(Grant Nos.52476067,52306078,and 52576053).
文摘As an emerging thermal management strategy,dynamic radiative cooling(DRC)technology enables dynamic modulation of spectral radiation properties under varying environmental conditions through the directional design of material spectral characteristics.However,a comprehensive review of the basic physical mechanisms of radiative heat transfer in DRC materials and various design principles involved in dynamic radiative thermal regulation is still lacking.This review systematically summarizes recent advances in this field,spanning from fundamental physical principles to intrinsic molecular and electronic mechanisms,and further to representative material systems and multi-band regulation strategies,highlighting the interdisciplinary research achievements and technological innovations.This work outlines the core mechanisms governing the regulation of different spectral bands during radiative heat transfer processes.Then,the main categories of DRC materials are systematically reviewed,including actively responsive structures,passively responsive structures,and multi-stimuli-responsive materials.Furthermore,the challenges faced by current DRC technology and future development trends are summarized and discussed,providing valuable reference and guidance for further research in this field.Although DRC technologies still face significant challenges in material stability,manufacturing processes,and system integration,the continuous advances in related areas and multifunctional materials are expected to broaden the application prospects of DRC in the future.
基金supported by National Natural Science Foundation of China(61921002 and 92163204)。
文摘Van der Waals(vdW)heterostructures have attracted much attention due to their distinctive optical,electrical,and thermal properties,demonstrating promising potential in areas such as photocatalysis,ultrafast photonics,and free electron radiation devices.Particularly,they are promising platforms for studying thermionic emission.It is illustrated that using vdW heterostructure-based thermionic emission can enhance heat transfer in vacuum devices.As a proof of concept,the approach is demonstrated to offer a promising solution for the long-standing overheating issue in X-ray tubes.Specifically,it is shown that the saturated target temperature of a 2000 W X-ray tube can be reduced from around 1200℃ to 490℃.Additionally,it is also demonstrated that by reducing the height of the Schottky barrier formed in the vdW heterostructures,the thermionic cooling performance can be enhanced.The findings pave the way for the development of high-power X-ray tubes.
文摘This article presents an adaptive intelligent control strategy applied to a lumped-parameter evaporator model,i.e.,a simplified dynamic representation treating the evaporator as a single thermal node with uniform temperature distribution,suitable for control design due to its balance between physical fidelity and computational simplicity.The controller uses a wavelet-based neural proportional,integral,derivative(PID)controller with IIR filtering(infinite impulse response).The dynamic model captures the essential heat and mass transfer phenomena through a nonlinear energy balance,where the cooling capacity“Qevap”is expressed as a non-linear function of the compressor frequency and the temperature difference,specifically,Q_(evap)=k_(1)u(T_(in)−T_(e))with u as compressor frequency,Te evaporator temperature,and Tin inlet fluid temperature.The operating conditions of the system,in general terms,focus on the following variables,the overall thermal capacity is 1000 J/K,typical for small-capacity heat exchangers,The mass flow is 0.05 kg/s,typical for secondary liquid cooling circuits,the overall loss coefficient of 50 W/K that corresponds to small evaporators with partial insulation,the temperatures(inlet)of 10℃and the temperature of environment of 25℃,thermal load of 200 W that corresponds to a small-scaled air conditioning applications.To handle system nonlinearities and improve control performance,aMorlet wavelet-based neural network(Wavenet)is used to dynamically adjust the PID gains online.An IIR filter is incorporated to smooth the adaptive gains,improving stability and reducing oscillations.In contrast to prior wavelet-or neural-adaptive PID controllers in HVAC applications,which typically adjust gains without explicit filtering or not tailored to evaporator dynamics,this work introduces the first PID–Wavenet scheme augmented with an IIR-based stabilization layer,specifically designed to address the combined challenges of nonlinear evaporator behavior,gain oscillation,and real-time implementability.The proposed controller(PID-Wavenet+IIR)is implemented and validated inMATLAB/Simulink,demonstrating superior performance compared to a conventional PID tuned using Simulink’s auto-tuning function.Key results include a reduction in settling time from 13.3 to 8.2 s,a reduction in overshoot from 3.5%to 0.8%,a reduction in steady-state error from 0.12℃ to 0.02℃and a 13%reduction in energy overall consumption.The controller also exhibits greater robustness and adaptability under varying thermal loads.This explicit integration of wavelet-driven adaptation with IIR-filtered gain shaping constitutes the main methodological contribution and novelty of the work.These findings validate the effectiveness of the wavelet-based adaptive approach for advanced thermal management in refrigeration and HVAC systems,with potential applications in controlling variable-speed compressors,liquid chillers,and compact cooling units.
基金support from the Key Research and Development Program of Shandong Province(No.2022SFGC0501)Shenzhen Science and Technology Program(International Cooperation Research)(No.GJHZ20240218113407015)+9 种基金Shenzhen Fundamental Research Program(Natural Science Foundation)(No.JCYJ20240813175900001)support from the Australian Research Council through the Discovery Project scheme(Grant No.DP190103186,DP220100603)support through the Future Fellowship scheme(Grant No.FT210100806)Discovery Project scheme(Grant No.DP250100980)Linkage Project scheme(LP210200345)the Industrial Transformation Research Hubs(Grant No.IH240100009)support through the Future Fellowship scheme(Grant No.FT220100559)Linkage Projects(Grant No.LP210100467)support through the Discovery Early Career Researcher Award scheme(DE230100383)support from the Natural Science Foundation of Shandong Province(Grant No.ZR2021ME162).
文摘Governed by the second law of thermodynamics,waste heat generation is inevitable and has been a major source of energy loss and environmental concern in human society.Harvesting waste heat into useful energy has thus become a paramount priority,but has remained challenging with efficiency and cost constraints.Thermoelectric generators(TEGs),which convert heat into electricity whenever there is a temperature difference,play a crucial role in waste heat harvesting.However,sustaining the temperature difference for uninterrupted and high-power density electricity generation is a major challenge in TEGs to achieve practical applications due to the thermal equilibrium.Here,we demonstrate a diurnal waste heat harvester by integrating a high-power radiative cooling film as the cool end of TEGs to enable a large and continuous temperature difference.Significant voltage increase from 30.0 mV to 65.7 mV was achieved,leading to a dramatic power density enhancement of 4.8 times from 35.2 mW m^(-2)to 168.6 mW m^(-2).In an open zone,an ultra-high power density of 2.76 W m^(-2)was achieved at a heat source temperature of 80°C,exceeding the performance of state-of-the-art radiatively cooled TEGs.More importantly,a portable and foldable thermal energy harvesting prototype composed of 24 TEGs arranged in an array has been constructed.When attached to a hot object(e.g.a car engine hood),it can output 5 V to charge personal electronics(e.g.a cellphone),making it a promising practical device for harvesting waste heat in a wide range of outdoor applications.
基金financial support from the National Natural Science Foundation of China(No.52374342)the Science and Technology Program of Guangxi Province(Guike ZY23055009).
文摘To fulfill diverse performance requirements in various industrial fields,it is essential to precisely control the inclusion characteristics in 316L stainless steel(316L SS),including chemical composition,size,and quantity and so on,thus ensuring the steel with high cleanliness and quality.Solidification experiments with different cooling methods were conducted using an Al_(2)O_(3)-CaO-SiO_(2)-MgO refining slag system to investigate the influence of cooling methods upon the characteristic variation and growth behavior of inclusions in 316L SS during the solidification process.Thermodynamic mechanisms underlying the inclusion composition transition during the solidification process were revealed,and a kinetic model for the prediction of the solute element segregation and the inclusion growth in the steel was developed and verified.Results indicated that a nonlinear fitting curve equation for the correlation between the average size of inclusions d and the cooling rate R_(c) was obtained,which was:d=3.728·R_(c)^(-0.134).As the cooling rate went down,Al_(2)O_(3) content in the inclusions correspondingly decreased from 69.43 to 30.54 mass%,while the SiO_(2) content increased from 14.75 to 43.8 mass%.The final inclusion size,calculated by the kinetic inclusion growth model,increased from 2.37 to 9.65μm as the cooling rate was reduced from 56.7 to 0.7 K s^(−1),which were in fair agreement with experimental results.
