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Beneficial effects of deep cryogenic treatment on mechanical properties of additively manufactured high entropy alloy:cyclic vs single cryogenic cooling

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Journal of Materials Science & Technology 2022年第20期115卷 40-51页

作者： hongge Li wenjie Zhao Tian Chen Yongjiang huang Jianfei Sun Ping Zhu Yunzhuo Lu Alfonso h.w.ngan Daqing wei Qing Du Yongchun Zou School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Dalian Jiaotong UniversityDalian 116028China Department of Mechanical Engineering The University of Hong KongHong KongChina Center of Analysis Measurement and Computing Harbin Institute of TechnologyHarbin 150001China

Additively manufactured(AM)metallic materials commonly possess substantial tensile surface residual stress,which is detrimental to the load-bearing service ***,we demonstrated that deep cryogenic treatment(DCT)is an effective method for improving the tensile properties of CoCrFeMnNi high-entropy alloy(hEA)samples fabricated by laser melting deposition(LMD),by introducing high compressive residual stress and deformation microstructures without destroying the AM ***,carrying out the DCT in a single-step mode does not improve the residual stress gradients inherent from the LMD process,which are undesirable as the mechanical properties will not be homogeneous within the *** this work,we show that carrying out the DCT in a cyclic mode with repeated cryogenic cooling and reheating can significantly homogenize the residual stress in LMD-fabricated Co Cr Fe Mn Ni hEA,and improve tensile strength and ductility,compared with single-step DCT of the same cryogenic soaking *** cyclic DCT,the thermal stress is re-elevated to a high value at each cryogenic cooling step,leading to the formation of denser and more intersecting reinforcing crystalline defects and hcp phase transformation,compared to single-step DCT of the same total cryogenic soaking duration in which the thermal stress relaxes towards a low value over *** enhancement of defect formation in the cyclic mode of DCT also leads to more uniform residual stress distribution in the sample after the *** results here provide important insights on optimizing DCT processes for post-fabrication improvement of mechanical properties of AM metallic net shapes.

关键词： Additive manufacturing high entropy alloy Deep cryogenic treatment Residual stress Mechanical properties

Potential and policy issues for sustainable development of wind power in China

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Journal of Modern Power Systems and Clean Energy 2013年第3期1卷 204-215页

作者： Zhongfu TAN h.w.ngan Yang wU huijuan ZhANG Yihang SONG Chao YU School of Economics and Management North China Electric Power UniversityBeijingChina School of Economics and Management Shanghai University of Electric PowerShanghaiChina Department of Electrical Engineering The Hong Kong Polytechnic UniversityHong KongChina

This paper presents a macroscopic view on the prevailing policy and potential issues in respect of the sustainable wind power development in *** starts by analyzing the characteristics of wind power resources and pin-pointing the relationship between the regulatory policies and various economic,taxation,legal and grid integration attributes relating to the wind power *** it follows by analyzing the status quo and capabilities of the wind power manufacturing industry in China including its operational efficiency and grid integration *** economic and environmental benefits are estimated by relating to the associated costing analysis in respect of the major contributing factors such as manufacturing,operational and financial *** of the associated benefits analysis indicate that the use of the wind power generation helps to save a significant equivalent amount of standard coal consumption resulting to reduction of emission ***,the potential of wind power development in China is shown to be affirmative and the sustainable energy policy is effectively implemented in China.

关键词： wind power Renewable energy policy Sustainable development Energy saving Emission reduction

Effects of hydrogen charging and deformation on tensile properties of a multi-component alloy for nuclear applications

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Tungsten 2022年第3期4卷 212-218页

作者： Te Zhu Zhi-hong Zhong Koichi Sato Ya-Min Song Feng-Jiao Ye Qian-Qian wang Ye Dong Peng Zhang Run-Sheng Yu Bao-Yi wang Alfonso h.w.ngan Xing-Zhong Cao Qiu Xu Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong KongChina Institute of high Energy Physics Chinese Academy of SciencesBeijing100049China Institute for Integrated Radiation and Nuclear Science Kyoto UniversityOsaka5900494Japan School of Materials Science and Engineering Hefei University of TechnologyHefei230009China Graduate School of Science and Engineering Kagoshima UniversityKagoshima8900065Japan

In this study,the influence of hydrogen charging and deformation on the tensile behavior of a 60Fe-12Cr-10Mn-15Cu-3Mo multi-component alloy was investigated using electron microscopy and positron annihilation lifetime *** results show that hydrogen-induced vacancy clusters found in the electrochemically charged hydrogen specimens are responsible for crack *** ingress to the microstructure,hydrogen promotes the formation of cell-structured dislocations that are beneficial for the improvement of tensile *** addition,hydrogen embrittlement can be mitigated by dislocations that can hinder hydrogen mobility in the deformed specimens.

关键词： hydrogen embrittlement Dislocation cell Multi-component alloys

The quasi-Gramian solution of a non-commutative extension of the higher-order nonlinear Schr?dinger equation

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Communications in Theoretical Physics 2024年第3期76卷 51-61页

作者： h w A Riaz J Lin Department of Physics Zhejiang Normal UniversityJinhua 321004China

The nonlinear Schr?dinger(NLS)equation,which incorporates higher-order dispersive terms,is widely employed in the theoretical analysis of various physical *** this study,we explore the non-commutative extension of the higher-order NLS *** treat real or complex-valued functions,such as g_(1)=g_(1)(x,t)and g_(2)=g_(2)(x,t)as non-commutative,and employ the Lax pair associated with the evolution equation,as in the commutation *** derive the quasi-Gramian solution of the system by employing a binary Darboux *** soliton solutions are presented explicitly within the framework of *** visually understand the dynamics and solutions in the given example,we also provide simulations illustrating the associated ***,the solution can be used to study the stability of plane waves and to understand the generation of periodic patterns within the context of modulational instability.

关键词： integrable systems Darboux transformation solitons

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基于代理的电力市场仿真的实验设计方法探讨

电力系统自动化 2009年第17期33卷 56-60,85页

作者：王野平荆朝霞陈皓勇颜汉荣张尧华南理工大学电力学院广东省广州市510040 香港理工大学电机工程学系

基于代理的计算经济学已经成为电力市场研究的一种重要方法,但是,作为一种新的方法,还有许多问题没有解决,其中一个基本的问题是研究方法的问题,包括仿真实验的设计方法、仿真结果的分析方法等。文中首先给出了电力市场仿真中一些关键... 详细信息

基于代理的计算经济学已经成为电力市场研究的一种重要方法,但是,作为一种新的方法,还有许多问题没有解决,其中一个基本的问题是研究方法的问题,包括仿真实验的设计方法、仿真结果的分析方法等。文中首先给出了电力市场仿真中一些关键概念的定义,然后以电力市场研究中常用的一种代理学习算法——Roth-Erev法为例,基于一个拥有4个发电商的日前电力市场,进行了市场模型、智能代理模型、实验目的及实验方案的设计。设计了3组实验,根据前2个实验的结果,对基于代理的电力市场仿真实验轮数的设定、实验盘数的设定等问题进行了分析和讨论,最后一个实验对Roth-Erev算法中一些参数的选取问题进行了探讨,展示了其在选取时的矛盾性,并从加强学习法的机理上分析了其原因。

关键词：电力市场计算经济学仿真智能代理 Roth-Erev加强学习法

Superplasticity of fine-grained Mg-10Li alloy prepared by severe plastic deformation and understanding its deformation mechanisms

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Journal of Magnesium and Alloys 2024年第1期12卷 316-331页

作者： h.T.Jeong S.w.Lee w.J.Kim Department of Materials Science and Engineering Hongik UniversityMapo-guSangsu-dong 72-1Seoul 121-791Republic of Korea

The superplastic behavior and associated deformation mechanisms of a fine-grained Mg-10.1 Li-0.8Al-0.6Zn alloy(LAZ1011)with a grain size of 3.2μm,primarily composed of the BCCβphase and a small amount of the hCPαphase,were examined in a temperature range of 473 K to 623 *** microstructural refinement of this alloy was achieved by employing high-ratio differential speed *** best superplasticity was achieved at 523 K and at strain rates of 10^(-4)-5×10^(-4)s^(-1),where tensile elongations of 550±600%were *** the heating and holding stage of the tensile samples prior to tensile loading,a significant increase in grain size was observed at temperatures above 573 ***,it was important to consider this effect when analyzing and understanding the superplastic deformation behavior and *** the investigated strain rate range,the superplastic flow at low strain rates was governed by lattice diffusion-controlled grain boundary sliding,while at high strain rates,lattice diffusion-controlled dislocation climb creep was the rate-controlling deformation *** was concluded that solute drag creep is unlikely to *** the late stages of deformation at 523 K,it was observed that grain boundary sliding led to the agglomeration of theαphase,resulting in significant strain *** mechanism maps were constructed forβ-Mg-Li alloys in the form of 2D and 3D formats as a function of strain rate,stress,temperature,and grain size,using the constitutive equations for various deformation mechanisms derived based on the data of the current tests.

关键词： Magnesium-lithium alloy Superplasticity Severe plastic deformation Grain size Grain growth

Feasibility and safety of minimally invasive multivisceral resection for T4b rectal cancer:A 9-year review

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world Journal of Gastrointestinal Surgery 2024年第3期16卷 777-789页

作者： Kai Siang Chan Biquan Liu Ming ngan Aloysius Tan Kwang Yeong how Kar Yong wong Department of General Surgery Tan Tock Seng HospitalSingapore 308433Singapore

BACKGROUND Colorectal cancer is the third most common cancer and the second highest cause of cancer-related mortality *** 5%-10%of patients are diagnosed with locally advanced rectal cancer(LARC)on *** LARC invading into other structures(i.e.T4b),multivisceral resection(MVR)and/or pelvic ex-enteration(PE)remains the only potential curative surgical *** and/or PE is a major and complex surgery with high post-operative *** invasive surgery(MIS)has been shown to improve short-term post-operative outcomes in other gastrointestinal malignancies,but there is little evi-dence on its use in MVR,especially so for robotic *** is a single-center retrospective cohort study from 1st January 2015 to 31st March *** criteria were patients diagnosed with cT4b rectal cancer and underwent MVR,or stage 4 disease with resectable systemic ***-tients who underwent curative MVR for locally recurrent rectal cancer,or me-tachronous rectal cancer were also *** criteria were patients with systemic metastases with non-resectable *** patients planned for elective surgery were enrolled into the standard enhanced recovery after surgery pathway with standard peri-operative management for colorectal *** sur-gery was defined based on technical difficulty of surgery(*** PE,bladder-sparing prostatectomy,pelvic lymph node dissection or need for flap creation).Our primary outcomes were the margin status,and complication ***-gorical values were described as percentages and analysed by the chi-square *** variables were expressed as median(range)and analysed by Mann-whitney U *** overall survival(OS)and recurrence-free survival(RFS)were analysed using Kaplan-Meier estimates with life table ***-rank test was performed to determine statistical significance between cumulative *** significance was defined as Pwith li

关键词： Laparoscopy Minimally invasive surgical procedures Multivisceral resection Pelvic Exenteration Rectal neoplasms Robotic surgical procedures

Microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with different prestrain levels

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Journal of Materials Science & Technology 2024年第4期171卷 80-93页

作者： Y.h.Zhang h.Li Z.w.Yang X.Liu Q.F.Gu State Key Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi Key Laboratory of high-Performance Precision Forming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(SMA)is a promising material in the aerospace field due to its wide transformation *** application of shape memory effect depends on multistep thermomechan-ical loading,viz.,low-temperature deformation and subsequent heating to ***-temperature deformation prestrain plays a pivotal role in shape memory properties tailoring of SMA ***,microstructure evolution and deformation mechanisms of Ni_(47)Ti_(44)Nb_(9)SMA subjected to vari-ous prestrain levels are still *** this end,microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subjected to multistep thermomechanical loading with prestrain levels of 8%-16%at-28℃(M_(s)+30℃)were *** results demonstrate that the stress-strain curve of the specimen exhibits four distinct stages at a maximal prestrain of 16%.whereas stageⅡand stageⅢend at prestrains of∼8%and∼12%,*** stageⅡ,the stress-induced martensitic transformation is accompanied by the dislocation slip of the NiTi matrix andβ-Nb *** stageⅢ,in addition to the higher density of dislocations and further growth of stress-induced martensite variants(SIMVs),(001)compound twins are introduced as a result of the(001)deformation twinning in stress-induced ***{20-1}martensite twins are gradually introduced in stageⅣ.Correspondingly,after subsequent unloading and heating,a higher density of{114}austenite twins form in the specimen with a larger prestrain of 16%.with increasing prestrain from 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases first and then ***ε_(re)^(T)obtains a maximum of 7.03%at 10%prestrain and de-creases to 6.17%at 16%*** increase ofε_(re)^(T)can be attributed to the formation of new SIMVs,the further growth of existing SIMVs,and the recoverable(001)compound *** the decrease ofε_(re)^(T)is mainly associated with the irrecoverable strain by{20−1}martensite *** effe

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy wide transformation hysteresis Thermomechanical loading Microstructure evolution Shape memory behaviors Stress-induced martensitic transformation Deformation twinning

Rational design of AgGaS/ZnS/ZnS quantum dots with a near-unity photoluminescence quantum yield via double shelling scheme

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Journal of Materials Science & Technology 2024年第2期169卷 235-242页

作者： h.X.Lu h.Liu Z.Z.Fu Y.Y.Chen h.Q.Dai Z.hu w.L.Zhang R.Q.Guo Institute for Electric Light Sources School of Information Science and TechnologyFudan UniversityShanghai 200433China Institute of Future Lighting Academy for Engineering and TechnologyFudan UniversityShanghai 200433China Yiwu Research Institute of Fudan University YiwuZhejiang 322000China Zhongshan-Fudan Joint Innovation Center Zhongshan 528437China

In this study,a two-step method was used to synthesize highly luminescent AgGaS/ZnS/ZnS quantum dots(QDs).In the first step,an inner ZnS shell was formed via a one-pot method,which resulted in a smaller lattice mismatch between the AgGaS core and the outer ZnS shell,thereby facilitating the formation of a thick outer *** the two-step shelling process,the synthesized AgGaS/ZnS/ZnS QDs showed an excellent photoluminescence quantum yield(PLQY)of 96.4%with a peak wavelength of 508 nm,repre-senting the highest PLQY reported thus far for AgGaS ***,the effect of halogen ions in Zn precursors on the shelling process was *** was proposed that the capacity of halogen ions to coordinate with the QDs influenced the balance between Zn cation diffusion and ZnS shelling ***,the ZnS shelling reaction was dominant when ZnCl_(2)was employed,while Zn cation diffusion was the dominant process under the I^(−)-rich *** work provides insights into the interfacial restructuring during the ZnS shelling and offers a clear map for the tailored synthesis of core/shell QDs.

关键词： AgGaS Quantum dots Photoluminescence Core/shell Alloyed core/shell interface