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Formation of spheroidal microstructure in semi-solid state and thixoforming of 7075 high strength aluminum alloy

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Rare Metals 2015年第10期34卷 710-716页

作者： Chang-Peng Wang Ze-Jun Tang Hua-Sheng Mei Ling Wang Rong-Qiang Li Di-Fan Li Environmental Testing Center No. 59 Institute of China Ordnance Industry Corrosion and Protection Center University of Science and Technology Beijing Mechanical and Electrical College Nanjing University of Aeronautics & Astronautics

The effects of isothermal holding process on the microstructure evolution of semi-solid 7075 strength aluminum alloy produced by the recrystallisation and partial remelting(RAP) process were investigated. Tensile mechanical properties of as-received and thixoformed alloys at room temperature were examined. The results show that the microstructure of as-received alloy exhibits remarkable orientation along the deformation *** the increase of isothermal holding time, the solid particle grain size continuously increases and the degree of spheroidization also improves. Coalescence mechanism is dominant when reheated at 595 °C and Ostwald ripening mechanism is dominant when reheated at 615 °C in the semi-solid state. A lower coarsening rate is observed for 615 °C(coarsening rate K = 391 μm3 s-1) compared with the coarsening rate for 595 °C(coarsening rate K = 501 μm3 s-1). The RAP 7075 aluminum alloy can be successfully thixoformed and the filling of components is good after thixoforming. The thixoformed components exhibit favorite mechanical properties.

关键词： 7075 High strength aluminum alloy Spheroidal micro

An Integral Representation for the Weighted Geometric Mean and Its Applications

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Acta Mathematica Sinica,English Series 2014年第1期30卷 61-68页

作者： Feng QI Xiao Jing ZHANG Wen Hui LI School of Mathematics and Informatics He'nan Polytechnic University The 59th Middle School Luoyang Department of Mathematics School of ScienceTianjin Polytechnic University

By virtue of Cauchy’s integral formula in the theory of complex functions,the authors establish an integral representation for the weighted geometric mean,apply this newly established integral representation to show that the weighted geometric mean is a complete Bernstein function,and find a new proof of the well-known weighted arithmetic-geometric mean inequality.

关键词： Integral representation Cauchy's integral formula arithmetic mean geometric mean weighted arithmetic-geometric mean inequality complete Bernstein function new proof application

Effect of heat treatment on microstructures and mechanical properties of a bulk nanostructured Al-Zn-Mg-Cu alloy

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 672-676页

作者： Han-bin Chen Bin Yang State Key Laboratory for Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China No.59 Institute of China Ordnance Industry Chongqing 400039 China

A bulk nanostructured Al-10.0Zn-2.8Mg-1.8Cu alloy was synthesized by cryomilling first and then by spark plasma sintering （SPS）, and the effect of heat treatment on the microstructures and mechanical properties of this alloy were studied. Most MgZn2 particles with a coarse size lie on the grain boundaries of the SPS-processed sample. After solid solution and artificial aging, fine spherical-like MgZn2 particles precipitate uniformly in the grain interiors. No obvious grain growth is found after the heat treatment. A nanoindentation study indicates that no clear change is found in the Yong＇s modulus of the nanostructured alloy after the heat treatment. However, the hardness of the nanostructured alloy increases by about 33% after the heat treatment, which is attributed to the effect of precipitation-hardening.

关键词： bulk nanostructured materials Al-Zn-Mg-Cu alloy nanoindentation microstructure mechanical properties precipitation-hardening

Wellbore stability analysis to determine the safe mud weight window for sandstone layers

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Petroleum Exploration and Development 2019年第5期46卷 1031-1038页

作者： DARVISHPOUR Ayoub CHERAGHI SEIFABAD Masoud WOOD David Anthony GHORBANI Hamzeh Department of Mining Engineering Isfahan University of TechnologyIsfahan ***Iran DWA Energy Limited LincolnLN59JPUnited Kingdom Southern Oil Fields National Iranian Oil CompanyTeheran ***Iran

The wellbore stability of a vertical well through the sandstone reservoir layers of the Asmari oil-bearing formation in south-west Iran is *** safe drilling-fluid density range for maintaining wellbore stability is determined and simulated using FLAC3 D software and a finite volume model established with drilled strata geomechanical *** initiation of plastic condition is used to determine the safe mud weight window(SMWW)in specific sandstone *** effects of rock strength parameters,major stresses around the wellbore and pore pressure on the SMWW are investigated for this *** analysis reveals that a reduction in cohesion and internal friction angle values leads to a significant narrowing of the *** the other hand,the reduction of pore pressure and the ratio between maximum and minimum horizontal stresses causes the SMWW to widen *** ability to readily quantify changes in SMWW indicates that the developed model is suitable as a well planning and monitoring tool.

关键词： wellbore stability wellbore geomechanical property safe mud weight window wellbore instability risk factors drilling stress simulation

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Venture capital reputation: a blessing or a curse for entrepreneurial firm innovation--a contingent effect of industrial distance

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Frontiers of Business Research in China 2019年第2期13卷 144-168页

作者： Han Liang Gang Liu Jianling Yin Business School Renmin University of China 59 Zhongguancun Street Haidian District Beijing 100872 China

This study investigates whether venture capital reputation is a blessing or a curse for entrepreneurial firm innovation by using data from 1,553 observations of venture capital investments on entrepreneurial firms in China's New Over-the-Counter (OTC) Market. Advantages that venture capital brings to entrepreneurial firms have been widely ack no wledged in exta nt research. However, our research emphasizes the potential resource outflows rather tha n in flows when firms are embedded in a shared reputable venture capital, and finds that the curse effect of venture capital reputation on entrepreneurial firms is manifested. Furthermore, we develop the concept of venture capital ntra-industrial reputationM and "extra-industrial reputation" to give a contingent answer to the z/blessing or curse" question. The conclusions are draw n in dicating that the curse effect is contingent o n in dustrial dista nee. Venture capital intra-industrial reputation is positively linked to entrepreneurial firm innovation, whereas extra-industrial reputation exerts a strong negative impact, which is responsible for the curse effect.

关键词： Venture capital reputation Intra-industrial reputation Extra-industrial reputation Curse effect Entrepreneurial firm innovation Industrial distance

The End of Western Marxism?On the Unravelling of an Ideological Structure

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Fudan Journal of the Humanities and Social Sciences 2023年第2期16卷 123-143页

作者： Roland Boer School of Philosophy Renmin University of China59 Zhongguancun StreetHaidian DistrictBeijing100872China

This study examines the proposition that the ideological structure of“Western Marxism”began to unravel after 1989 and the end of the Cold War,and that it is now largely falling *** argument proceeds in three steps,the first of which is an overview of Western Marxism’s ideological *** second step analyses a number of deeply critical assessments of Western Marxism from within the contexts of the few countries of the world that make up the“West.”The fact that these critical and often polemical studies are appearing indicates the breakdown of Western Marxism’s former *** third step deals with more constructive material,including the Western“recovery”of Engels,and especially the dialectics of nature,as well as the impact of the major achievements in the theory and practice of Marxism from developing countries,in the context of socialism in power.

关键词： Western Marxism Ideological structure Cold War context Criticism Recovering the full Marxist tradition

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口述史在国内外护理领域的应用进展

军事护理 2024年第4期41卷 88-90页

作者：吴燕铭毛娅赵丹王方星周雨欣王巧红曹慧丽杨辉山西医科大学护理学院山西太原030001 上海交通大学医学院附属仁济医院护理部上海200127 苏州大学苏州医学院护理学院江苏苏州215006 伦敦国王学院西西里桑德斯研究所伦敦SE59PJ

口述史(oral history)亦称口述历史,是一种将“看”与“听”融合,采用一定的工具,通过访谈和收集实物等方式获取人们的记忆、感受和经验,分析对历史有意义的内容,丰富历史内涵的史学研究方法[1]。口述史不仅是个人生平阅历、历史经验和... 详细信息

口述史(oral history)亦称口述历史,是一种将“看”与“听”融合,采用一定的工具,通过访谈和收集实物等方式获取人们的记忆、感受和经验,分析对历史有意义的内容,丰富历史内涵的史学研究方法[1]。口述史不仅是个人生平阅历、历史经验和感情世界的记录,也是一定时期历史事件的生动记录[2]。在护理史研究中,口述史既能弥补历史断层,也可补充或重现文献史料[3]。同时,作为一种动态的历史教育方法,口述史能在护理发展与社会文明进程的互动中,激发护士对护理的觉醒与思考,让其深刻地认识护理专业的底蕴与价值,凝聚与塑造护士的职业认同,提升人文关怀的素养[4]。本文通过对口述史的起源和发展、特点与优势、实施步骤及其在护理领域的应用进行综述,旨在强化护理研究者对口述史的认识,以期为我国开展护理口述史相关研究提供借鉴。

关键词：口述史国外护理国内护理

A Truncated Marxism:On the Ideological Structure of Western Marxism

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Fudan Journal of the Humanities and Social Sciences 2023年第2期16卷 145-170页

作者： Roland Boer School of Philosophy Renmin University of China59 Zhongguancun StreetHaidian DistrictBeijing100872China

This study presents an overview of the ideological framework of“Western Marxism.”This framework has a number of components,which are described in terms of a series of reductions,determinations,and the suspicions entertained by Western *** result was a truncated type of Marxism that cut itself off from the Marxist–Leninist *** did so by reducing Marxism to the works of Marx alone and calling this“historical materialism,”which entailed a rejection of Engels’s significant contributions in history,science,and theory,and thus entailed a rejection of the subsequent developments of *** Western Marxism has been primarily promoted by“freelance intellectuals”with virtually no connection to Workers’or Communist Parties and was determined by an assumed ideological position before a proletarian revolution,was shaped by Western liberalism and imperialism,and has been constantly tempted into religiously inspired utopian versions of *** deep suspicions of the state and national liberation,of science and technology,and of the importance of productive forces,this Western Marxism was always hoping for the ideal revolution(or even better,a peaceful transition)that would very quickly produce a utopian socialist society organised only by the people and without a *** ideological framework also entailed a dismissal of the actual experience in developing countries of successful proletarian revolutions and the construction of socialism.

关键词： Western Marxism Ideological structure Reductions Determinations Suspicions

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钢质焊接药筒长贮性能研究

兵工学报 2004年第1期25卷 26-29页

作者：罗天元张伦武中国兵器工业第59研究所

钢质焊接药筒的大量使用 ,其长贮性能引起人们广泛关注。通过其典型自然环境下的贮存和户外暴露试验 ,以及实验室条件下的光老化、热老化、盐雾试验、应力腐蚀试验等 ,研究了其腐蚀、焊缝应力腐蚀与电偶腐蚀、表面防蚀工艺等。得出了钢... 详细信息

钢质焊接药筒的大量使用 ,其长贮性能引起人们广泛关注。通过其典型自然环境下的贮存和户外暴露试验 ,以及实验室条件下的光老化、热老化、盐雾试验、应力腐蚀试验等 ,研究了其腐蚀、焊缝应力腐蚀与电偶腐蚀、表面防蚀工艺等。得出了钢质焊接药筒在长贮条件下对应力腐蚀、电偶腐蚀等局部腐蚀不敏感 ,药筒制造工艺、涂装工艺合理。

关键词：钢质药筒长贮性能焊接金属材料腐蚀