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Charged torus-like black holes as heat engines

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Communications in Theoretical Physics 2021年第4期73卷 104-110页

作者： Hanwen feng Yuchen huang Wei Hong jun Tao Center for Theoretical Physics College of PhysicsSichuan UniversityChengdu610064China

We investigate the thermodynamical properties of charged torus-like black holes and take it as the working substance to study the heat *** the extended phase space,by interpreting the cosmological constant as the thermodynamic pressure,we derive the thermodynamical quantities by the first law of black hole thermodynamics and obtain the equation of ***,we calculate the efficiency of the heat engine in the Carnot cycle as well as the rectangular cycle,and investigate how the efficiency changes with respect to *** addition,to avoid a negative temperature,we emphasize that the charge of this black hole cannot be ***,we check the calculation accuracy of a benchmark scheme and discuss the upper bound and lower bound for charged torus-like black hole in the scheme.

关键词： charged torus-like black holes heat engines benchmark scheme

Multiple α sub-variants and anisotropic mechanical properties of an additively-manufactured Ti-6Al-4V alloy

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Journal of Materials Science & Technology 2021年第11期70卷 113-124页

作者： Yinling Zhang Zhuo Chen Shoujiang Qu Aihan feng Guangbao Mi jun Shen xu huang Daolun Chen School of Materials Science and Engineering Tongji UniversityShanghai 201804China Department of Mechanical and Industrial Engineering Ryerson UniversityTorontoOntario M5B 2K3Canada Aerospace Hiwing(Harbin)Titanium Industrial Co. Ltd.Harbin High Tech ZoneHarbin 150028China Shanghai Key Lab.of D&A for Metal-Functional Materials School of Materials Science&EngineeringTongji UniversityShanghai 201804China Aviation Key Laboratory of Science and Technology on Advanced Titanium Alloys AECC Beijing Institute of Aeronautical MaterialsBeijing 100095China College of Mechatronics and Control Engineering Shenzhen UniversityShenzhen 518060China

Additive manu facturing(AM)is a promising material processing method which gains significant momentum in the aerospace and biomedical ***,the anisotropy in the mechanical properties of additively-manufactured materials is still poorly *** study was aimed at elucidating crystallographic feature-anisotropy-mechanical property relationship for a Ti-6Al-4V alloy manufactured via selective electron beam melting(SEBM).Abundantαlamellae with six variants were present inside the columnar prior-βgrains with afiber texture duringβ→αphase *** sixαvariants followed the Burgers orientation relationship of{110}_(β)//{0001}_(α)and_(β)//_(α).Multiple sub-variants in eachαvariant were observed for the first *** anisotropy in the mechanical properties was mainly related to the relative amount of sixα*** the horizontally-oriented samples had a lower yield strength,they exhibited a higher ductility and longer fatigue life than the vertically-oriented *** softening occurred at higher strain amplitudes,and cyclic stabilization sustained at lower strain *** crack mainly initiated from the specimen surface at lower strain amplitudes,while multiple crack initiation tended to occur at higher strain *** propagation was characterized by fatigue striations along with some secondary cracks.

关键词： Titanium alloy 3D printing Deformation behavior Anisotropy Burgers orientation relationship

A poor performance in comprehensive geriatric assessment is associated with increased fall risk in elders with hypertension： a cross-sectional study

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Journal of Geriatric Cardiology 2015年第2期12卷 113-118页

作者： Jiao-Jiao CHU xu-Jiao CHEN Shan-Shan SHEN xue-feng ZHANG Ling-Yan CHEN jing-Mei ZHANG jing HE jun-feng ZHAO Department of Geriatrics Zhejiang Hospital Hangzhou 310013 Zhefiang Province China Fuyuan Hospital of Yiwu Yiwu 322000 Zhejiang Province China Department of Emergency Zhejiang Hospital Hangzhou 310013 Zhejiang Province China

Background Fall and serious fall injuries have become a major health concern for elders. Many factors including blood pressure and anti-hypertensive medication application were reported as hazards of fall. The purpose of this study was to determine if age related systemic functional decline related with increased fall risks in elderly patients with hypertension. Methods A total of 342 elderly hypertension patients （age 79.5 ＋ 6.7 years, male 63.8%） were recruited to the study. Comprehensive geriatric assessment （CGA）, including measurements about activity of daily living （ADL）, nutrition, cognition, depression, numbers of prescription medication and number of clinical diagnosis, was conducted to evaluate the physical and mental status of each participants. Fall risk was evaluated by Morse fall scale, Tinetti perform- ance oriented mobility assessment （POMA） and history of fall in the recent years. Participants were grouped into tertiles according to CGA score. Correlation between CGA and fall risk was analyzed through SPSS 18.0. Results Participants with higher CGA score were likely to be older, had a lower body mass index （BMI）, and a higher prevalence of cardiovascular disease, chronic obstructive pulmonary disease （COPD）, cerebrovascular disease and osteoarthropathia. Participants in higher tertile of CGA score got increased prevalence of fall risk than those in lower tertile （P 〈 0.01 T3 vs. T1, P 〈 0.01 T3 vs. T2）. Correlation analysis and regression analysis showed significant association between CGA and Morse fall scale （P 〈 0.001）, as well as CGA and POMA （P 〈 0.001）. Meanwhile, CGA components also showed co-relationships with increase fall risks. After adjusting age, BMI, benzodiazepine use, cardiovascular disease, cerebrovascular disease, COPD and osteoarthropathia, both history of fall in the recent year and rising Morse fall scale were significantly associated with ADL im- pairment （OR： 2.748, 95%CI： 1.598-4.725）, （OR： 3.310, 95%CI： 1.893-5.788）. Decreas

关键词： Comprehensive geriatric assessment Elderly patient Fall risk Hypertension

Application of split Hopkinson tension bar technique to the study of dynamic fracture properties of materials

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Acta Mechanica Sinica 2012年第2期28卷 424-431页

作者： Ze-Jian xu Yu-Long Li feng-Lei huang State Key Laboratory of Explosion Science and Technology Beijing Institute of Technology100081 BeijingChina School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China

A novel approach is proposed in determining dy- namic fracture toughness （DFT） of high strength steel, using the split Hopkinson tension bar （SHTB） apparatus, com- bined with a hybrid experimental-numerical method. The center-cracked tension specimen is connected between the bars with a specially designed fixture device. The fracture initiation time is measured by the strain gage method, and dynamic stress intensity factors （DSIF） are obtained with the aid of 3D finite element analysis （FEA）. In this approach, the dimensions of the specimen are not restricted by the connec- tion strength or the stress-state equilibrium conditions, and hence plane strain state can be attained conveniently at the crack tip. Through comparison between the obtained results and those in open publication, it is concluded that the ex- perimental data are valid, and the method proposed here is reliable. The validity of the obtained DFT is checked with the ASTM criteria, and fracture surfaces are examined at the end of paper.

关键词： Split Hopkinson tension bar Dynamic fracture toughness Hybrid experimental-numerical method High loading rate Failure mode

Influence of fruit maturity and lactic fermentation on physicochemical properties,phenolics,volatiles,and sensory of mulberry juice

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Food Bioscience 2022年第4期48卷 357-367页

作者： Kunhua Wang jing Qi Yu Jin feng Li jun Wang Huaide xu College of Food Science and Engineering Northwest A&F UniversityYangling712100China

Mulberry fruits harvested at commercial ripeness were sorted into five maturity groups(S1-S5)according to their density,and their juices were separately fermented at 37◦C for 36 h using Lactobacillus plantarum strain *** physicochemical properties,phenolic profile,antioxidant activity,flavor profile,and sensory characteristics of mulberry juice(MJ)were then *** findings revealed that MJs were suitable matrices for LP-01 growth,particularly for MJ-S5 with a high content of phenolics,glucose,and fructose,with more than 12 log CFU/mL of viable counts and 19.64 mg/mL of lactic acid at the end of *** acid bacteria(LAB)fermentation dramatically increased total phenolics,total flavonoids,and antioxidant capacities,while promoting anthocyanin transformation of ***,cyanidin-3-O-glucoside(C3G)was significantly decreased by LAB fermentation and negatively correlated with caffeic and chlorogenic acid contents(p<0.05).Lp-01 fermentation enhanced the total aroma content and complexity of flavor,specifically in MJ-S5 which resulted in the total aroma content increased by 54.96 mg/L and 11 new flavor volatiles ***,MJ-S3 fermentation product was the most attractive for *** results will be valuable in controlling of mulberries product quality precisely.

关键词： Morus nigra Maturity stages Lactic fermentation Physicochemical property Flavor volatiles Sensory evaluation

High-temperature friction behavior of amorphous carbon coating in glass molding process

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Friction 2021年第6期9卷 1648-1659页

作者： Kangsen LI Gang xu Xiaobin WEN jun ZHOU feng GONG Guangdong Provincial Key Laboratory of Micro/Nano Optomechatronics Engineering College of Mechatronics and Control EngineeringShenzhen UniversityShenzhen 518060China Shenzhen Kingmag Precision Techonology Co.LTD. Shenzhen 518172China

In the glass molding process,the sticking reaction and fatigue wear between the glass and mold hinder the service life and functional application of the mold at the elevated *** improve the chemical inertness and anti-friction properties of the mold,an amorphous carbon coating was synthesized on the tungsten carbide-cobalt(WC–8Co)substrate by magnetron *** friction behavior between the glass and carbon coating has a significant influence on the functional protection and service life of the ***,the glass ring compression tests were conducted to measure the friction coefficient and friction force of the contact interface between the glass and amorphous carbon coating at the high ***,the detailed characterization of the amorphous carbon coating was performed to study the microstructure evolution and surface topography of the amorphous carbon coating during glass molding process by scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS),Ramon spectroscopy,and atomic force microscope(AFM).The results showed that the amorphous carbon coating exhibited excellent thermal stability,but weak shear friction *** friction coefficient between the glass and coating depended on the ***,the service life of the coating was governed by the friction force of the contact interface,processing conditions,and composition *** work provides a better understanding of the application of carbon coatings in the glass molding.

关键词： glass molding process high temperature friction behavior amorphous carbon coating

Numerical simulation and cause analysis of persistent summer drought during the 1920s in eastern China

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Science China Earth Sciences 2022年第5期65卷 966-982页

作者： Meng LUO Jinming feng Zhongfeng xu jun WANG Li DAN Yunnan Climate Center Kunming 650034China Key Lab of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

In the late 1920’s,a mega-drought in China resulted in widespread crop failure and *** evidence suggests that this drought belonged to a dry period ranging from approximately 1922 to *** understand the characteristics and the cause of this persistent drought period,we combined various data,including observations,tree ring proxy data,reanalysis data,simulation results of the Fifth Phase of the Coupled Model Intercomparison Project and numerical downscaling *** results show that during 1922-1932,most regions in eastern China suffered from a persistent drought that lasted for six years,and the maximum negative precipitation anomaly reached−1.5 times the standard *** its spatial coverage,duration,and strength,the 1920s drought was unique for the 20th *** 1920s drought was primarily caused by internal *** easterlies in lower latitudes,strong monsoon circulation,and abnormally high geopotential heights at middle and upper levels were responsible for the 1920s drought conditions in eastern China;these drought conditions could be further attributed to the joint impact of the Atlantic Multidecadal Oscillation,Pacific Decadal Oscillation and Indian Ocean Basin Mode.

关键词： Drought 1920s Eastern China East Asia Summer Monsoon Regional Climate Model Atlantic Multidecadal Oscillation Pacific Decadal Oscillation Indian Ocean Basin Mode

Performance Analysis of a Combined Absorption Refrigeration-Liquid Desiccant Dehumidification THIC System Driven by Low-Grade Heat Source

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Journal of Thermal Science 2020年第5期29卷 1193-1205页

作者： xu Cong SUI jun DAI Yuze LIU feng LIU Hao Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Traditional condensing air-conditioning systems consume large amounts of energy in hot and humid areas,and it is difficult to achieve simultaneous control of temperature and humidity.A combined absorption refrigeration(AR)and liquid desiccant dehumidification(LDD)air-conditioning system based on cascade utilization of low-grade heat source is *** system can realize independent control of temperature and humidity and carry out profound recovery of low-grade heat *** the design conditions,the heat utilization rate C reaches 21.05%,which is 2.73 times that of the conventional absorption refrigeration reference system.A parametric sensitivity analysis is performed to optimize the *** C increases from 9.79%to 18.55%and the coefficient of performance C O P t increases from 0.33 to 0.35 with an increase in chilled water temperature from 7°C to 15°*** an increase in regenerant solution temperature from 60°C to 70°C,the C achieves the optimal value of 21.05%at 68°C.C decreases from 21.05%to 15.05%as the concentration of the regenerant solution increases from 36%to 40%.Under variable environmental temperature and humidity,the C the proposed system changes within a small range and stays much higher than that of the reference system with the same quality heat source,which indicates that the proposed system has a better adaptability to changing environmental parameters.

关键词： temperature and humidity independent control(THIC) low-grade heat source cascade utilization heat utilization rate

Electrocatalysis induced reconstruction of RuNiPO for highly efficient hydrogen evolution reaction

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Journal of Energy Chemistry 2023年第12期87卷 24-31,I0003页

作者： junhui Hu Bai xu Jiabin xu Shuo Li Zhonghu Liu Cheng Lu Yong feng Kun feng jun Zhong Institute of Functional Nano and Soft Materials Laboratory(FUNSOM) Jiangsu Key Laboratory of Advanced Negative Carbon TechnologiesSoochow UniversitySuzhou 215123JiangsuChina Department of Chemistry University of Western OntarioLondonOntario N6A 5B7Canada

Reconstruction during the catalytic process has been considered to play a key role for the *** we report a RuNiPO based catalyst for efficient alkaline hydrogen evolution reaction(HER),which can benefit from a long-term reconstruction during HER for 10 h to continuously increase the *** final catalyst(e-RuNiPO)shows a huge morphology change from bulk sphere to highly exposed layered structure in the electrocatalysis process,and exhibits an interesting electronic structure modification with the electron transfer from Ru to Ni for better interfacial interaction and quick charge *** to the favorable morphology with more exposed active sites and the optimized electronic structure,the final catalyst can achieve an outstanding performance with only an overpotential of 15 mV at 10 mA cm^(-2)(with a good stability more than 100 h),even outperforming the performance of benchmark 20 wt%Pt/C catalyst(18 mV at 10 mA cm^(-2))by using a much lower Ru content.

关键词： Electrocatalyst Electrochemical reconstruction Hydrogen evolution reaction X-ray absorption spectroscopy