The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,...The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,computing devices use the von Neumann architecture with separate computing and memory units,which exposes the shortcomings of“memory bottleneck”.Nonvolatile memristor can realize data storage and in-memory computing at the same time and promises to overcome this bottleneck.Phase-change random access memory(PCRAM)is called one of the best solutions for next generation non-volatile memory.Due to its high speed,good data retention,high density,low power consumption,PCRAM has the broad commercial prospects in the in-memory computing application.In this review,the research progress of phase-change materials and device structures for PCRAM,as well as the most critical performances for a universal memory,such as speed,capacity,and power consumption,are reviewed.By comparing the advantages and disadvantages of phase-change optical disk and PCRAM,a new concept of optoelectronic hybrid storage based on phase-change material is proposed.Furthermore,its feasibility to replace existing memory technologies as a universal memory is also discussed as well.展开更多
We numerically demonstrate a novel ultra-broadband polarization-independent metamaterial perfect absorber in the visible and near-infrared region involving the phase-change material Ge_2Sb_2Te_5(GST).The novel perfect...We numerically demonstrate a novel ultra-broadband polarization-independent metamaterial perfect absorber in the visible and near-infrared region involving the phase-change material Ge_2Sb_2Te_5(GST).The novel perfect absorber scheme consists of an array of high-index strong-absorbance GST square resonators separated from a continuous Au substrate by a low-index lossless dielectric layer(silica)and a high-index GST planar cavity.Three absorption peaks with the maximal absorbance up to 99.94% are achieved,owing to the excitation of plasmon-like dipolar or quadrupole resonances from the high-index GST resonators and cavity resonances generated by the GST planar cavity.The intensities and positions of the absorption peaks show strong dependence on structural parameters.A heat transfer model is used to investigate the temporal variation of temperature within the GST region.The results show that the temperature of amorphous GST can reach up to 433 K of the phase transition temperature from room temperature in just 0.37 ns with a relatively low incident light intensity of 1.11×10~8W∕m^2,due to the enhanced ultra-broadband light absorbance through strong plasmon resonances and cavity resonance in the absorber.The study suggests a feasible means to lower the power requirements for photonic devices based on a thermal phase change via engineering ultra-broadband light absorbers.展开更多
A tunable plasmonic perfect absorber with a tuning range of 650 nm is realized by introducing a 20 nm thick phase-change material Ge2Sb2Te5 layer into the metal–dielectric–metal configuration.The absorption at the p...A tunable plasmonic perfect absorber with a tuning range of 650 nm is realized by introducing a 20 nm thick phase-change material Ge2Sb2Te5 layer into the metal–dielectric–metal configuration.The absorption at the plasmonic resonance is kept above 0.96 across the whole tuning range.In this work we study this extraordinary optical response numerically and reveal the geometric conditions which support this phenomenon.This work shows a promising route to achieve tunable plasmonic devices for multi-band optical modulation,communication,and thermal imaging.展开更多
Regulating the indoor temperature of public transport on hot sunny days is a prime concern,as both the external and internal heat sources play an active role in heat gain.Experimental studies have been carried out on ...Regulating the indoor temperature of public transport on hot sunny days is a prime concern,as both the external and internal heat sources play an active role in heat gain.Experimental studies have been carried out on a bus model using sodium sulphate decahydrate as a phase-change material(PCM)that is placed in between the ceiling and the roof.Studies are conducted on a sunny day and also for different cases of external(300-W surface heater)and internal(25-W light bulb)heat sources.The results show that PCM,in the presence of an external heat source,can help to keep the indoor temperature lower and delay the time period for increasing the temperature by absorbing heat during the phase change.On the other hand,the presence of the internal heat source contributes to a detrimental effect on the indoor temperature,which gradually increases with the elapse of time.With the combination of the external and internal heat sources,it is found that the internal heat source plays a dominating factor to raise the indoor temperature.It is revealed from the experimental results that a 12.7-mm single layer and a single PCM are not enough to counter the internal heat of 25 W unless the thickness of the PCM layer is increased to delay the increase in the indoor temperature.An additional PCM layer with a lower melting temperature could be placed at the inner portion of the ceiling to have effective thermal-energy storage by absorbing the substantial heat gain from the internal heat sources.展开更多
A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silic...A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silicon was adopted to facilitate heat transfer. Moreover, high resistance or even insulation of CPCM is capable of preventing short circuits between the cells. The heat transfer mechanism of CPCMs was determined under a scanning electron microscope. A thermogravimetric analyzer was employed to determine the thermal stability. A diff erential scanning calorimeter was used to explore the thermophysical properties of the composite samples. By comparing the results of the experiment, it was reported that under the silicon carbide content of 5%, the parameters were better than others. The phase-change enthalpy of CPCM was 199.4 J/g, the leakage rate of liquid was 4.6%, and the melting point was 53.6℃. To verify the practicality of CPCM, a three-dimensional layered battery pack model was built in the COMSOL Multiphysics software. By simulating the thermal runaway inside the battery packs of various materials, it was reported that the addition of CPCM significantly narrowed the temperature range of the battery pack from 300–370 to 303–304 K. Therefore, CPCM can eff ectively increase the rate of heat transfer to prevent the chain of thermal runaway reactions. It also enables the battery pack to run at a stable temperature.展开更多
Phase-change material(PCM)is generating widespread interest as a new candidate for artificial synapses in bioinspired computer systems.However,the amorphization process of PCM devices tends to be abrupt,unlike contin...Phase-change material(PCM)is generating widespread interest as a new candidate for artificial synapses in bioinspired computer systems.However,the amorphization process of PCM devices tends to be abrupt,unlike continuous synaptic depression.The relatively large power consumption and poor analog behavior of PCM devices greatly limit their applications.Here,we fabricate a GeTe/Sb2Te3 superlattice-like PCM device which allows a progressive RESET process.Our devices feature low-power consumption operation and potential high-density integration,which can effectively simulate biological synaptic characteristics.The programming energy can be further reduced by properly selecting the resistance range and operating method.The fabricated devices are implemented in both artificial neural networks(ANN)and convolutional neural network(CNN)simulations,demonstrating high accuracy in brain-like pattern recognition.展开更多
Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the a...Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST,the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5μm to 13μm are realized.The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband.The simulation calculation results show that the fullwidth at half-maximum(FWHM)of the focusing spot reaches the diffraction limit at each wavelength.In addition,the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°.The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces,but also provides new possibilities for the integration of optical imaging,optical coding and other related optical systems.展开更多
The photovoltaic/thermal(PV/T)system is a promising option for countering energy shortages.To improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly ...The photovoltaic/thermal(PV/T)system is a promising option for countering energy shortages.To improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly applied to construct a concentrating photovoltaic/thermal system integrated with phase-change materials(PV/T-CPCM).An open-air environment is used to analyze the effects of different parameters and the intermittent operation strategy on the system performance.The results indicate that the short-circuit current and open-circuit voltage are positively correlated with the solar irradiance,but the open-circuit voltage is negatively correlated with the temperature of the PV modules.When the solar irradiance is 500 W⋅m^(−2) and the temperature of the PV modules is 27.5℃,the short-circuit current and open-circuit voltage are 1.0 A and 44.5 V,respectively.Higher solar irradiance results in higher thermal power,whereas the thermal efficiency is under lower solar irradiance(136.2-167.1 W⋅m^(−2) is twice under higher solar irradiance(272.3-455.7 W⋅m^(−2))).In addition,a higher mass flow rate corresponds to a better cooling effect and greater pump energy consumption.When the mass flow rate increases from 0.01 to 0.02 kg⋅s^(-1),the temperature difference between the inlet and outlet decreases by 1.8℃,and the primary energy-saving efficiency decreases by 0.53%.The intermittent operation of a water pump can reduce the energy consumption of the system,and the combination of liquid cooling with PCMs provides better thermal regulation and energy-saving effects under various conditions.展开更多
Optical neural networks (ONNs), enabling low latency and high parallel data processing withoutelectromagnetic interference, have become a viable player for fast and energy-efficient processing andcalculation to meet t...Optical neural networks (ONNs), enabling low latency and high parallel data processing withoutelectromagnetic interference, have become a viable player for fast and energy-efficient processing andcalculation to meet the increasing demand for hash rate. Photonic memories employing nonvolatile phase-change materials could achieve zero static power consumption, low thermal cross talk, large-scale, andhigh-energy-efficient photonic neural networks. Nevertheless, the switching speed and dynamic energyconsumption of phase-change material-based photonic memories make them inapplicable for in situ training.Here, by integrating a patch of phase change thin film with a PIN-diode-embedded microring resonator,a bifunctional photonic memory enabling both 5-bit storage and nanoseconds volatile modulation wasdemonstrated. For the first time, a concept is presented for electrically programmable phase-changematerial-driven photonic memory integrated with nanosecond modulation to allow fast in situ training and zerostatic power consumption data processing in ONNs. ONNs with an optical convolution kernel constructedby our photonic memory theoretically achieved an accuracy of predictions higher than 95% when testedby the MNIST handwritten digit database. This provides a feasible solution to constructing large-scalenonvolatile ONNs with high-speed in situ training capability.展开更多
It is of great importance to treat a bacterial-infected wound by a smart dressing capable of delivering antibiotics in a smart manner without causing drug resistance.The construction of smart release nanocontainers re...It is of great importance to treat a bacterial-infected wound by a smart dressing capable of delivering antibiotics in a smart manner without causing drug resistance.The construction of smart release nanocontainers responsive to near-infrared(NIR)laser irradiation in an on-demand and stepwise way is a promising strategy for avoiding the emergence of multidrug-resistant bacteria.Here,we develop a hydrogel composite made of alginate and nanotubes with an efficient NIR-triggered release of rifampicin and outstanding antibacterial ability.This composite hydrogel is prepared through co-encapsulating antibacterial drug(rifampicin),NIR-absorbing dye(indocyanine green),and phase-change materials(a eutectic mixture of fatty acids)into halloysite nanotubes,followed by incorporation into alginate hydrogels,allowing the in-situ gelation at room temperature and maintaining the integrity of drug-loaded nanotubes.Among them,the eutectic mixture with a melting point of 39℃ serves as the biocompatible phase-change material to facilitate the NIR-triggered drug release.The resultant phase-change material gated-nanotubes exhibit a prominent photothermal efficiency with multistep drug release under laser irradiation.In an in vitro assay,composite hydrogel provides good antibacterial potency against Staphylococcus aureus,one of the most prevalent microorganisms of dangerous gas gangrene.A bacterial-infected rat full-thickness wound model demonstrates that the NIR-responsive composite hydrogel inhibits the bacteria colonization and suppresses the inflammatory response caused by bacteria,promoting angiogenesis and collagen deposition to accelerate wound regeneration.The NIR-responsive composite hydrogel has a great po-tential as an antibacterial wound dressing functionalized with controlled multistep treatment of the infected sites.展开更多
Recently, although renewable energy has a great development, primary source is still thermal power generation, which uses fossil fuel as the energy source. Supply and demand of fossil fuel are essential for social and...Recently, although renewable energy has a great development, primary source is still thermal power generation, which uses fossil fuel as the energy source. Supply and demand of fossil fuel are essential for social and economy development. However, development pattern that excessively relies on the natural source is impossible to provide a sustainable development way for us. As a result, we should combine renewable energy with new energy technology as the aim of economy. It means that it is urgent to exploit new energy. Meanwhile, the ratio of energy waste cannot be ignored. How to decrease energy waste is also significant. Construction sector costs a lot of energy, which is mainly used for heating and refrigeration. In the new energy generation technology, thermal energy can be transformed to electricity with combination of BIPV and thermal energy storage technology. Photovoltaic generation has a great progress in the building construction. As a result, the thermal energy storage technology becomes the key link in the production chain. In this paper, feasibility of applying phase-change material (PCM) in the thermal energy storage will be analyzed. And analysis results are provided with a relative mathematical model.展开更多
This manuscript addresses the futuristic energy savings by impregnating building elements with PCM formations. Two structured gypsum building walls were monitored under the transient heat mode in the conducted experim...This manuscript addresses the futuristic energy savings by impregnating building elements with PCM formations. Two structured gypsum building walls were monitored under the transient heat mode in the conducted experiments. One wall included (phase-change material) spheres, integrated into one styrofoam layer, installed at different positions, from 1 to 5, from the outside to the inside of the room. The other wall included one styrofoam insulation layer, perforated with holes, with changeable positions, from 1 to 5, from the outside to the inside of the room. The temperatures in the experiment corresponded to high summer temperatures in the tropical or subtropical zones. The obtained experimental results were further analyzed, while HVAC is off, for an indoor thermal comfort range, from 20˚C to 25˚C. This manuscript has analyzed the thermal comfort, effectiveness and optimal position of PCM spheres, incorporated in styrofoam thermal insulation, for a previously determined temperature range. The wall with integrated PCM should not be thick, (in total), but rather slender so that PCM can show its effectiveness. The farthermost position of the PCM layer should be the third because PCM combined with a lot of thermal insulation is not so effective and the thermal insulation has a buffer effect. The honeycomb or hollow-core thermal insulations should be avoided to put alone, because of natural air convection in them, which raises the heat flow. The monthly monetary saving, for a PCM-integrated wall, is calculated and amounts to 55.5 $, which shows that the integration of PCM in building walls, in hot summer locations, is very beneficial.展开更多
太阳能除冰是环境友好的新型除冰/防冰方法,然而太阳能辐射的间歇性导致光热效率降低,限制了其发展.本文以膨胀石墨为光热载体,通过真空浸渍法将相变剂与之复合,再利用聚二甲基硅氧烷(PDMS)热固定型得到光热相变复合材料,并探究了其光...太阳能除冰是环境友好的新型除冰/防冰方法,然而太阳能辐射的间歇性导致光热效率降低,限制了其发展.本文以膨胀石墨为光热载体,通过真空浸渍法将相变剂与之复合,再利用聚二甲基硅氧烷(PDMS)热固定型得到光热相变复合材料,并探究了其光热转化性能与防冰/除冰能力.结果表明复合材料不仅能实现光热转化,同时由于相变剂的作用能够进行热能的存储与释放,且表现出优越的防冰/除冰性能.在-40℃,一个太阳光强的条件下,材料表面的液滴延缓结冰时间超过2 h,在不同环境温度下表面除冰速率最高可达2.21 kg m^(-2)h^(-1).此外,此光热相变复合材料还表现出极高的可重复利用性.该材料是一类很有应用前景的高效光热防冰/除冰材料.展开更多
Compact nanophotonic elements exhibiting adaptable properties are essential components for the miniaturization of powerful optical technologies such as adaptive optics and spatial light modulators.While the larger cou...Compact nanophotonic elements exhibiting adaptable properties are essential components for the miniaturization of powerful optical technologies such as adaptive optics and spatial light modulators.While the larger counterparts typically rely on mechanical actuation,this can be undesirable in some cases on a microscopic scale due to inherent space restrictions.Here,we present a novel design concept for highly integrated active optical components that employs a combination of resonant plasmonic metasurfaces and the phase-change material Ge3Sb2Te6.In particular,we demonstrate beam switching and bifocal lensing,thus,paving the way for a plethora of active optical elements employing plasmonic metasurfaces,which follow the same design principles.展开更多
基金the National Natural Science Foundation of China(Grant Nos.21773291,61904118,and 22002102)the Natural Science Foundation of Jiangsu Province,China(Grant Nos.BK20190935 and BK20190947)+3 种基金the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(Grant Nos.19KJA210005,19KJB510012,19KJB120005,and 19KJB430034)the Fund from the Suzhou Key Laboratory for Nanophotonic and Nanoelectronic Materials and Its Devices(Grant No.SZS201812)the Science Fund from the Jiangsu Key Laboratory for Environment Functional Materialsthe State Key Laboratory of Transducer Technology,Shanghai Institute of Microsystem and Information Technology,Chinese Academy of Sciences.
文摘The era of information explosion is coming and information need to be continuously stored and randomly accessed over long-term periods,which constitute an insurmountable challenge for existing data centers.At present,computing devices use the von Neumann architecture with separate computing and memory units,which exposes the shortcomings of“memory bottleneck”.Nonvolatile memristor can realize data storage and in-memory computing at the same time and promises to overcome this bottleneck.Phase-change random access memory(PCRAM)is called one of the best solutions for next generation non-volatile memory.Due to its high speed,good data retention,high density,low power consumption,PCRAM has the broad commercial prospects in the in-memory computing application.In this review,the research progress of phase-change materials and device structures for PCRAM,as well as the most critical performances for a universal memory,such as speed,capacity,and power consumption,are reviewed.By comparing the advantages and disadvantages of phase-change optical disk and PCRAM,a new concept of optoelectronic hybrid storage based on phase-change material is proposed.Furthermore,its feasibility to replace existing memory technologies as a universal memory is also discussed as well.
基金973 Program of China(2013CB632704)National Natural Science Foundation of China(NSFC)(11374357,11434017)
文摘We numerically demonstrate a novel ultra-broadband polarization-independent metamaterial perfect absorber in the visible and near-infrared region involving the phase-change material Ge_2Sb_2Te_5(GST).The novel perfect absorber scheme consists of an array of high-index strong-absorbance GST square resonators separated from a continuous Au substrate by a low-index lossless dielectric layer(silica)and a high-index GST planar cavity.Three absorption peaks with the maximal absorbance up to 99.94% are achieved,owing to the excitation of plasmon-like dipolar or quadrupole resonances from the high-index GST resonators and cavity resonances generated by the GST planar cavity.The intensities and positions of the absorption peaks show strong dependence on structural parameters.A heat transfer model is used to investigate the temporal variation of temperature within the GST region.The results show that the temperature of amorphous GST can reach up to 433 K of the phase transition temperature from room temperature in just 0.37 ns with a relatively low incident light intensity of 1.11×10~8W∕m^2,due to the enhanced ultra-broadband light absorbance through strong plasmon resonances and cavity resonance in the absorber.The study suggests a feasible means to lower the power requirements for photonic devices based on a thermal phase change via engineering ultra-broadband light absorbers.
基金the support from the National Research Foundation,Prime Minister’s Office,Singapore under its Competitive Research Program (CRP Award No.NRF-CRP10-2012-04)funding from the Leverhulme trust and the EPSRC Active Plasmonics Programm+1 种基金funding provided by the 973 Program of China (No.2013CBA01700)the Chinese Natural Sciences Grant (61138002 and 61307043)
文摘A tunable plasmonic perfect absorber with a tuning range of 650 nm is realized by introducing a 20 nm thick phase-change material Ge2Sb2Te5 layer into the metal–dielectric–metal configuration.The absorption at the plasmonic resonance is kept above 0.96 across the whole tuning range.In this work we study this extraordinary optical response numerically and reveal the geometric conditions which support this phenomenon.This work shows a promising route to achieve tunable plasmonic devices for multi-band optical modulation,communication,and thermal imaging.
基金supported by the Mechanical and Production Engineering Department(MPE)of Ahsanullah University of Science and Technology(AUST).
文摘Regulating the indoor temperature of public transport on hot sunny days is a prime concern,as both the external and internal heat sources play an active role in heat gain.Experimental studies have been carried out on a bus model using sodium sulphate decahydrate as a phase-change material(PCM)that is placed in between the ceiling and the roof.Studies are conducted on a sunny day and also for different cases of external(300-W surface heater)and internal(25-W light bulb)heat sources.The results show that PCM,in the presence of an external heat source,can help to keep the indoor temperature lower and delay the time period for increasing the temperature by absorbing heat during the phase change.On the other hand,the presence of the internal heat source contributes to a detrimental effect on the indoor temperature,which gradually increases with the elapse of time.With the combination of the external and internal heat sources,it is found that the internal heat source plays a dominating factor to raise the indoor temperature.It is revealed from the experimental results that a 12.7-mm single layer and a single PCM are not enough to counter the internal heat of 25 W unless the thickness of the PCM layer is increased to delay the increase in the indoor temperature.An additional PCM layer with a lower melting temperature could be placed at the inner portion of the ceiling to have effective thermal-energy storage by absorbing the substantial heat gain from the internal heat sources.
基金supported by the National Key Research and Development Projects(No.2018YFC0808600)。
文摘A lithium-ion battery thermal management system has always been a hot spot in the battery industry. In this study, a novel high-thermal-conductivity composite phase-change material(CPCM) made by paraffin wax and silicon was adopted to facilitate heat transfer. Moreover, high resistance or even insulation of CPCM is capable of preventing short circuits between the cells. The heat transfer mechanism of CPCMs was determined under a scanning electron microscope. A thermogravimetric analyzer was employed to determine the thermal stability. A diff erential scanning calorimeter was used to explore the thermophysical properties of the composite samples. By comparing the results of the experiment, it was reported that under the silicon carbide content of 5%, the parameters were better than others. The phase-change enthalpy of CPCM was 199.4 J/g, the leakage rate of liquid was 4.6%, and the melting point was 53.6℃. To verify the practicality of CPCM, a three-dimensional layered battery pack model was built in the COMSOL Multiphysics software. By simulating the thermal runaway inside the battery packs of various materials, it was reported that the addition of CPCM significantly narrowed the temperature range of the battery pack from 300–370 to 303–304 K. Therefore, CPCM can eff ectively increase the rate of heat transfer to prevent the chain of thermal runaway reactions. It also enables the battery pack to run at a stable temperature.
基金Project supported by the National Science and Technology Major Project of China(Grant No.2017ZX02301007-002)the National Key R&D Plan of China(Grant No.2017YFB0701701)the National Natural Science Foundation of China(Grant Nos.61774068 and 51772113).The authors acknowledge the support from Hubei Key Laboratory of Advanced Memories&Hubei Engineering Research Center on Microelectronics.
文摘Phase-change material(PCM)is generating widespread interest as a new candidate for artificial synapses in bioinspired computer systems.However,the amorphization process of PCM devices tends to be abrupt,unlike continuous synaptic depression.The relatively large power consumption and poor analog behavior of PCM devices greatly limit their applications.Here,we fabricate a GeTe/Sb2Te3 superlattice-like PCM device which allows a progressive RESET process.Our devices feature low-power consumption operation and potential high-density integration,which can effectively simulate biological synaptic characteristics.The programming energy can be further reduced by properly selecting the resistance range and operating method.The fabricated devices are implemented in both artificial neural networks(ANN)and convolutional neural network(CNN)simulations,demonstrating high accuracy in brain-like pattern recognition.
基金Project supported by the Natural Science Foundation of Shaanxi Province,China(Grant No.2021JM466)
文摘Based on the phase-change material Ge_(2)Sb_(2)Te_(5)(GST),achromatic metasurface optical device in the longer-infrared wavelength is designed.With the combination of the linear phase gradient GST nanopillar and the adjustment of the crystalline fraction m value of GST,the polarization insensitive achromic metalenses and beam deflector metasurface within the longer-infrared wavelength 9.5μm to 13μm are realized.The design results show that the achromatic metalenses can be focused on the same focal plane within the working waveband.The simulation calculation results show that the fullwidth at half-maximum(FWHM)of the focusing spot reaches the diffraction limit at each wavelength.In addition,the same method is also used to design a broadband achromatic beam deflector metasurface with the same deflection angle of 19°.The method proposed in this article not only provides new ideas for the design of achromatic metasurfaces,but also provides new possibilities for the integration of optical imaging,optical coding and other related optical systems.
基金supported by the Hebei Province Postdoctoral Merit Funding Program(Grant No.:B2022005004)the Science and Tech-nology Nova Plan of Hebei University of Technology(Grant No.:JBKYXX2207)+2 种基金the National Natural Science Foundation of China(Grant No.:51978231)the S&T Program of Hebei(Project No.:216Z4502G)the Natural Science Foundation of Hebei Province(Grant No.:E2020202196).
文摘The photovoltaic/thermal(PV/T)system is a promising option for countering energy shortages.To improve the performance of PV/T systems,compound parabolic concentrators(CPCs)and phase-change materials(PCMs)were jointly applied to construct a concentrating photovoltaic/thermal system integrated with phase-change materials(PV/T-CPCM).An open-air environment is used to analyze the effects of different parameters and the intermittent operation strategy on the system performance.The results indicate that the short-circuit current and open-circuit voltage are positively correlated with the solar irradiance,but the open-circuit voltage is negatively correlated with the temperature of the PV modules.When the solar irradiance is 500 W⋅m^(−2) and the temperature of the PV modules is 27.5℃,the short-circuit current and open-circuit voltage are 1.0 A and 44.5 V,respectively.Higher solar irradiance results in higher thermal power,whereas the thermal efficiency is under lower solar irradiance(136.2-167.1 W⋅m^(−2) is twice under higher solar irradiance(272.3-455.7 W⋅m^(−2))).In addition,a higher mass flow rate corresponds to a better cooling effect and greater pump energy consumption.When the mass flow rate increases from 0.01 to 0.02 kg⋅s^(-1),the temperature difference between the inlet and outlet decreases by 1.8℃,and the primary energy-saving efficiency decreases by 0.53%.The intermittent operation of a water pump can reduce the energy consumption of the system,and the combination of liquid cooling with PCMs provides better thermal regulation and energy-saving effects under various conditions.
基金supported by the National Key Research and Development Program of China (2019YFB2203002 and 2021YFB2801300)National Natural Science Foundation of China (62105287, 91950204, and 61975179)Zhejiang Provincial Natural Science Foundation (LD22F040002)
文摘Optical neural networks (ONNs), enabling low latency and high parallel data processing withoutelectromagnetic interference, have become a viable player for fast and energy-efficient processing andcalculation to meet the increasing demand for hash rate. Photonic memories employing nonvolatile phase-change materials could achieve zero static power consumption, low thermal cross talk, large-scale, andhigh-energy-efficient photonic neural networks. Nevertheless, the switching speed and dynamic energyconsumption of phase-change material-based photonic memories make them inapplicable for in situ training.Here, by integrating a patch of phase change thin film with a PIN-diode-embedded microring resonator,a bifunctional photonic memory enabling both 5-bit storage and nanoseconds volatile modulation wasdemonstrated. For the first time, a concept is presented for electrically programmable phase-changematerial-driven photonic memory integrated with nanosecond modulation to allow fast in situ training and zerostatic power consumption data processing in ONNs. ONNs with an optical convolution kernel constructedby our photonic memory theoretically achieved an accuracy of predictions higher than 95% when testedby the MNIST handwritten digit database. This provides a feasible solution to constructing large-scalenonvolatile ONNs with high-speed in situ training capability.
基金National Natural Science Foundation of China(Grant No.82002049 and 52073014,to J.X.)Key Program of Beijing Natural Science Foundation(Z200025)+1 种基金Fundamental Research Funds for the Central Universities(buctrc202020)YL thanks support by T.Pipes Nano Microsystem Endowment,Louisiana Tech University,USA.
文摘It is of great importance to treat a bacterial-infected wound by a smart dressing capable of delivering antibiotics in a smart manner without causing drug resistance.The construction of smart release nanocontainers responsive to near-infrared(NIR)laser irradiation in an on-demand and stepwise way is a promising strategy for avoiding the emergence of multidrug-resistant bacteria.Here,we develop a hydrogel composite made of alginate and nanotubes with an efficient NIR-triggered release of rifampicin and outstanding antibacterial ability.This composite hydrogel is prepared through co-encapsulating antibacterial drug(rifampicin),NIR-absorbing dye(indocyanine green),and phase-change materials(a eutectic mixture of fatty acids)into halloysite nanotubes,followed by incorporation into alginate hydrogels,allowing the in-situ gelation at room temperature and maintaining the integrity of drug-loaded nanotubes.Among them,the eutectic mixture with a melting point of 39℃ serves as the biocompatible phase-change material to facilitate the NIR-triggered drug release.The resultant phase-change material gated-nanotubes exhibit a prominent photothermal efficiency with multistep drug release under laser irradiation.In an in vitro assay,composite hydrogel provides good antibacterial potency against Staphylococcus aureus,one of the most prevalent microorganisms of dangerous gas gangrene.A bacterial-infected rat full-thickness wound model demonstrates that the NIR-responsive composite hydrogel inhibits the bacteria colonization and suppresses the inflammatory response caused by bacteria,promoting angiogenesis and collagen deposition to accelerate wound regeneration.The NIR-responsive composite hydrogel has a great po-tential as an antibacterial wound dressing functionalized with controlled multistep treatment of the infected sites.
文摘Recently, although renewable energy has a great development, primary source is still thermal power generation, which uses fossil fuel as the energy source. Supply and demand of fossil fuel are essential for social and economy development. However, development pattern that excessively relies on the natural source is impossible to provide a sustainable development way for us. As a result, we should combine renewable energy with new energy technology as the aim of economy. It means that it is urgent to exploit new energy. Meanwhile, the ratio of energy waste cannot be ignored. How to decrease energy waste is also significant. Construction sector costs a lot of energy, which is mainly used for heating and refrigeration. In the new energy generation technology, thermal energy can be transformed to electricity with combination of BIPV and thermal energy storage technology. Photovoltaic generation has a great progress in the building construction. As a result, the thermal energy storage technology becomes the key link in the production chain. In this paper, feasibility of applying phase-change material (PCM) in the thermal energy storage will be analyzed. And analysis results are provided with a relative mathematical model.
文摘This manuscript addresses the futuristic energy savings by impregnating building elements with PCM formations. Two structured gypsum building walls were monitored under the transient heat mode in the conducted experiments. One wall included (phase-change material) spheres, integrated into one styrofoam layer, installed at different positions, from 1 to 5, from the outside to the inside of the room. The other wall included one styrofoam insulation layer, perforated with holes, with changeable positions, from 1 to 5, from the outside to the inside of the room. The temperatures in the experiment corresponded to high summer temperatures in the tropical or subtropical zones. The obtained experimental results were further analyzed, while HVAC is off, for an indoor thermal comfort range, from 20˚C to 25˚C. This manuscript has analyzed the thermal comfort, effectiveness and optimal position of PCM spheres, incorporated in styrofoam thermal insulation, for a previously determined temperature range. The wall with integrated PCM should not be thick, (in total), but rather slender so that PCM can show its effectiveness. The farthermost position of the PCM layer should be the third because PCM combined with a lot of thermal insulation is not so effective and the thermal insulation has a buffer effect. The honeycomb or hollow-core thermal insulations should be avoided to put alone, because of natural air convection in them, which raises the heat flow. The monthly monetary saving, for a PCM-integrated wall, is calculated and amounts to 55.5 $, which shows that the integration of PCM in building walls, in hot summer locations, is very beneficial.
基金financially supported by the National Natural Science Foundation of China (21875261, 51925307 and 21733010)the National Key Research and Development Program of China (2020YFE0100300 and 2018YFA0208502)+1 种基金the Key Research Program of Frontier Sciences, Chinese Academy of Sciences (ZDBS-LYSLH031)the Youth Innovation Promotion Association of the Chinese Academy of Sciences (2018044)。
文摘太阳能除冰是环境友好的新型除冰/防冰方法,然而太阳能辐射的间歇性导致光热效率降低,限制了其发展.本文以膨胀石墨为光热载体,通过真空浸渍法将相变剂与之复合,再利用聚二甲基硅氧烷(PDMS)热固定型得到光热相变复合材料,并探究了其光热转化性能与防冰/除冰能力.结果表明复合材料不仅能实现光热转化,同时由于相变剂的作用能够进行热能的存储与释放,且表现出优越的防冰/除冰性能.在-40℃,一个太阳光强的条件下,材料表面的液滴延缓结冰时间超过2 h,在不同环境温度下表面除冰速率最高可达2.21 kg m^(-2)h^(-1).此外,此光热相变复合材料还表现出极高的可重复利用性.该材料是一类很有应用前景的高效光热防冰/除冰材料.
基金support by the ERC Advanced Grant(COMPLEXPLAS)BMBF(13N9048 and 13N10146)+3 种基金the Baden Württemberg Stiftung(Internationale Spitzenforschung II)DFG(SPP1391,FOR730 and GI 269/11-1)SFB 917(Resistive Nanoswitches)support by the Carl-Zeiss-Stiftung。
文摘Compact nanophotonic elements exhibiting adaptable properties are essential components for the miniaturization of powerful optical technologies such as adaptive optics and spatial light modulators.While the larger counterparts typically rely on mechanical actuation,this can be undesirable in some cases on a microscopic scale due to inherent space restrictions.Here,we present a novel design concept for highly integrated active optical components that employs a combination of resonant plasmonic metasurfaces and the phase-change material Ge3Sb2Te6.In particular,we demonstrate beam switching and bifocal lensing,thus,paving the way for a plethora of active optical elements employing plasmonic metasurfaces,which follow the same design principles.
