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A review on different theoretical models of electrocaloric effect for refrigeration

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Frontiers in Energy 2023年第4期17卷 478-503页

作者： cancan SHAO A.A.AMIROV Houbing HUANG School of Materials Science and Engineering Beijing Institute of TechnologyBeijing100081China Advanced Research Institute of Multidisciplinary Science Beijing Institute of TechnologyBeijing100081China Amirkhanov Institute of Physics Daghestan Scientific Center Russian Academy of SciencesMakhachkala367003Russia

The performance parameters for characterizing the electrocaloric effect are isothermal entropy change and the adiabatic temperature change,*** paper reviews the electrocaloric effect of ferroelectric materials based on different theoretical ***,it provides four different calculation scales(the first-principle-based effective Hamiltonian,the Landau-Devonshire thermodynamic theory,phase-field simulation,and finite element analysis)to explain the basic theory of calculating the electrocaloric ***,it comprehensively reviews the recent progress of these methods in regulating the electrocaloric effect and the generation mechanism of the electrocaloric ***,it summarizes and anticipates the exploration of more novel electrocaloric materials based on the framework constructed by the different computational methods.

关键词： electrocaloric effect effective Hamiltonian phase-field modeling different theoretical models

An Update Review on Performance Enhancement of Refrigeration Systems Using Nano-Fluids

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Journal of Thermal Science 2022年第4期31卷 1236-1251页

作者： XING Meibo ZHANG Hongfa ZHANG cancan Beijing Engineering Research Center of Sustainable Energy and Buildings School of Environment and Energy EngineeringBeijing University of Civil Engineering and ArchitectureBeijing 100044China MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation Beijing Key Laboratory of Heat Transfer and Energy ConversionBeijing University ofTechnologyBeijing 100124China

Considering the issues of energy saving and environment protection,the performance of refrigeration systems requires to be *** recent years,nano-fluids have attracted greatly attention from the researchers due to their outstanding thermal *** this work,the published investigations on the preparation and characterization of nano-fluids have been discussed at ***,the key thermo-physical properties of nano-fluids,such as thermal conductivity,viscosity,specific heat and density have been ***,the performance enhancements in different types of refrigeration systems by using nano-fluids have been *** is concluded that nano-fluids as refrigerant,lubricant or secondary fluid have wide potential application in refrigeration systems.

关键词： nano-fluids performance enhancement nano-refrigerant nano-lubricant nano-secondary fluid refrigeration

Plasmonic metal/semiconductor hybrid nanomaterials for solar to chemical energy conversion

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Journal of Energy Chemistry 2021年第12期30卷 40-53,I0002页

作者： cancan Zhang Yuying Zhang Wei Xie Key Lab of Advanced Energy Materials Chemistry(Ministry of Education) Renewable Energy Conversion and Storage CenterCollege of ChemistryNankai UniversityTianjin 300071China School of Medicine Nankai UniversityTianjin 300071China

Plasmonic nanomaterials are sources of light,heat and electrons at nanometer *** the outstanding performance in harvesting and converting solar energy under visible light irradiation,hybrid nanomaterials with plasmonic activity have recently emerged as a new class of advanced *** of the enhanced charge-separation at hybrid interfaces,the hybrids usually exhibit higher catalytic activity compared with their monometallic ***,we review the recent progress on synthesis of plasmonic hybrid nanomaterials and their applications in photocatalysis,including H2 production,CO_(2) reduction and N2 *** hope this review will give systematic and valuable reference on plasmonic solar to chemical energy conversion.

关键词： Plasmon Hybrid nanomaterials Energy conversion

Rational design of biodegradable thermoplastic polyurethanes for tissue repair

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Bioactive Materials 2022年第9期7卷 250-271页

作者： cancan Xu Yi Hong Department of Bioengineering University of Texas at ArlingtonArlingtonTX76019USA

As a type of elastomeric polymers,non-degradable polyurethanes(PUs)have a long history of being used in clinics,whereas biodegradable PUs have been developed in recent decades,primarily for tissue repair and *** thermoplastic(linear)PUs are soft and elastic polymeric biomaterials with high mechanical strength,which mimics the mechanical properties of soft and elastic ***,biodegradable thermoplastic polyurethanes are promising scaffolding materials for soft and elastic tissue repair and ***,PUs are synthesized by linking three types of changeable blocks:diisocyanates,diols,and chain *** the combination of these three blocks can finely tailor the physio-chemical properties and generate new functional *** PUs have excellent processing flexibilities and can be fabricated into three-dimensional(3D)constructs using conventional and/or advanced technologies,which is a great advantage compared with cross-linked thermoset ***,they can be combined with biomolecules to incorporate desired bioactivities to broaden their biomedical *** this review,we comprehensively summarized the synthesis,structures,and properties of biodegradable thermoplastic PUs,and introduced their multiple applications in tissue repair and regeneration.A whole picture of their design and applications along with discussions and perspectives of future directions would provide theoretical and technical supports to inspire new PU development and novel applications.

关键词： Biodegradable polyurethane Thermoplastic Elastic Synthesis Tissue repair

Spatio-temporal differentiation of spring phenology in China driven by temperatures and photoperiod from 1979 to 2018

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Science China Earth Sciences 2020年第10期63卷 1485-1498页

作者： Xiaojing WU Changxiu CHENG cancan QIAO Changqing SONG State Key Laboratory of Earth Surface Processes and Resource Ecology Beijing Normal UniversityBeijing 100875China Key Laboratory of Environmental Change and Natural Disaster Beijing Normal UniversityBeijing 100875China Faculty of Geographical Science Beijing Normal UniversityBeijing 100875China Center for Geodata and Analysis Beijing Normal UniversityBeijing 100875China

Large amounts of data accumulated in ecology and related environmental sciences arouses urgent need to explore useful patterns and information in *** we propose coclustering-based methods and a temperatures-photoperiod driven phenological model to explore spatio-temporal differentiation in long-term spring phenology in ***,we created the first bloom date(FBD)dataset in China from 1979 to 2018 using the extended spring indices and China Meteorological Forcing *** we analyzed the dataset using Bregman block average co-clustering algorithm with I-divergence(BBAC_I)and kmeans *** analysis delineated the spatially-continuous phenoregions in China for the first *** showed three spatial patterns of FBD in China and their temporal dynamics for 40 years(1979–2018).More specifically,overall late spring onsets occur in 1979–1996,in which areas located in Jiangxi,northern Xinjiang and middle Inner Mongolia experienced constant changing spring *** increasingly earlier spring onsets occur in 1997–2012,in which areas located in Fujian,Hunan and eastern Heilongjiang experienced the most variable spring *** early spring onsets over China occur after *** also showed 15 temporal patterns of spring phenology over the study period and their spatial delineation in *** specifically,most areas in China have the same FBD category for 40 years while northern Guizhou,Hunan and southern Hubei have the same category in 1979–1997 and then fluctuate between different ***,our results have certain directive significance on the design of existing observational sites in Chinese Phenological Network.

关键词： First bloom date Co-clustering Big data Spatio-temporal differentiation Temperatures-photoperiod driven phenological model

Enhanced dechlorination of 2,4-dichlorophenol by recoverable Ni/Fe–Fe_3O_4 nanocomposites

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Journal of Environmental Sciences 2016年第10期28卷 92-101页

作者： cancan Xu Rui Liu Lvjun Chen Jialu Tang Zhejiang Provincial Key Laboratory of Water Science and Technology Department of Environment Yangtze Delta Region Institute of Tsinghua University School of Environment Tsinghua University

Ni/Fe-Fe3O4 nanocomposites were synthesized for dechlorination of 2,4-dichlorophenol （2,4-DCP）. The effects of the Ni content in Ni/Fe-Fe3O4 nanocomposites, solution pH, and common dissolved ions on the dechlorination efficiency were investigated, in addition to the reusability of the nanocomposites. The results showed that increasing content of Ni in Ni/Fe-FesO4 nanocomposites, from 1 to 5 wt.%, greatly increased the dechlorination efficiency; the Ni/Fe-Fe3O4 nanocomposites had much higher dechlorination efficiency than bare Ni/Fe nanoparticles. Ni content of S wt.% and initial pH below 6.0 was found to be the optimal conditions for the catalytic dechlorination of 2,4-DCP. Both 2,4-DCP and the intermediate product 2-chlorophenol （2-CP） were completely removed, and the concentra- tion of the final product phenol was close to the theoretical phenol production from complete dechlorination of 20 mg/L of 2,4-DCP, after 3 hr reaction at initial pH value of 6.0, 3 g/L Ni/Fe-Fe3O4, S wt.% Ni content in the composite, and temperature of 22℃ 2,4-DCP dechlorination was enhanced by C1- and inhibited by NO3- and SO42-. The nanocomposites were easily separated from the solution by an applied magnetic field. When the catalyst was reused, the removal efficiency of 2,4-DCP was almost 100% for the first seven uses, and gradually decreased to 75% in cycles 8-10. Therefore, the Ni/Fe-Fe3O4 nanocomposites can be considered as a potentially effective tool for remediation of Pollution bv 2.4-DCP.

关键词： Ni/Fe-Fe3O4 nanocomposites2 4-DichlorophenolCatalytic dechlorinationRecoverableCommon dissolved ions

Neural Networks Combined with Importance Sampling Techniques for Reliability Evaluation of Explosive Initiating Device

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Chinese Journal of Aeronautics 2012年第2期25卷 208-215页

作者： GONG Qi ZHANG Jianguo TAN Chunlin WANG cancan Reliability System Engineering Institute Beihang Universitys Beij ing 100191 China Beijing lnstitute of Spacecraft System Engineering Beijing 100081 China

Concerning the issue of high-dimensions and low-failure probabilities including implicit and highly nonlinear limit state function, reliability analysis based on the directional importance sampling in combination with the radial basis function （RBF） neural network is used, and the RBF neural network based on first-order reliability method （FORM） is to approximate the unknown implicit limit state functions and calculate the most probable point （MPP） with iterative algorithm. For good efficiency, based on the ideas that directional sampling reduces dimensionality and importance sampling focuses on the domain contributing to failure probability, the joint probability density function of importance sampling is constructed, and the sampling center is moved to MPP to ensure that more random sample points draw belong to the failure domain and the simulation efficiency is improved. Then the numerical example of initiating explosive devices for rocket booster explosive bolts demonstrates the applicability, versatility and accuracy of the approach compared with other reliability simulation algorithm.

关键词： neural networks importance sampling explosive initiating device reliability nonlinearity

Significant reduction in friction and wear of a high-entropy alloy via the formation of self-organized nanolayered structure

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Journal of Materials Science & Technology 2021年第14期73卷 1-8页

作者： Lu Yang Zhuo Cheng Weiwei Zhu cancan Zhao Fuzeng Ren Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Institute of Applied Physics and Materials Engineering Faculty of Science&TechnologyUniversity of MacaoMacaoChina

Sliding wear-induced nanolayering and its positive impact on wear resistance have been observed in conventional binary alloys with a matrix of high stacking fault energy(SFE),but this concept has never been reported in high-entropy alloys(HEAs)with low ***,we design and fabricate a(CoCrFeNi)_(90)Ag_(10)HEA,consisting of a face-center-cubic(fcc)CoCrFeNi HEA matrix with low SFE and uniformly dispersed Ag *** comparison with CoCrFeNi,a significant reduction in friction and wear was found in(CoCrFeNi)_(90)Ag_(10)HEA through the spontaneous formation of nanolayered subsurface microstructure during *** finding suggests a novel approach for designing HEAs that can achieve low friction and wear.

关键词： High-entropy alloy Sliding wear Nanolayering

Spontaneous escape behavior of silver from graphite-like carbon coating and its inhibition mechanism

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Journal of Materials Science & Technology 2017年第11期33卷 1402-1408页

作者： Wenting Shao Xinyu Zhang Bailing Jiang cancan Liu Hongtao Li College of Materials Science and Engineering Nanjing Tech University College of Materials Science and Engineering Xi'an University of Technology

A series of silver-doped graphite-like carbon coatings was prepared on the surface of aluminum alloy using the magnetron sputtering method. The spontaneous escape behavior and inhibition mechanism of silver from graphite-like carbon coating were studied. The results showed that when the sample prepared with a 0.01-A current on the silver target was placed in an atmospheric environment for 0.5 h, an apparent silver escape phenomenon could be observed. However, the silver escape phenomenon was not observed for samples prepared with a 0.05-A current on the silver target if the sample was retained in a 10^（-1） Pa vacuum environment, even after 48 h. Compared with the sample placed in the atmospheric environment immediately after an ion plating process, the silver escape time lagged for 6 h. Nanometer-thick pure carbon coating coverage could effectively suppress silver escape. When the coating thickness reached700 nm, permanent retention of silver could be achieved in the silver-doped graphite-like carbon *** the silver residue content in the graphite-like carbon coating increased from 2.27 at.% to 5.35 at.%, the interfacial contact resistance of the coating decreased from 51mΩcm^2 to 6 mΩcm^2.

关键词： Silver Graphite-like carbon coating Spontaneous escape mechanism Inhibition mechanism Interfacial contact resistance