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Ultra-large aluminum shape casting:Opportunities and challenges

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China Foundry 2024年第5期21卷 397-408页

作者： Qi-gui Wang Andy Wang Jason Coryell Advanced Materials Technology&Virtualization GM Global Technical CenterWarrenMI USA

Ultra-large aluminum shape castings have been increasingly used in automotive vehicles,particularly in electric vehicles for light-weighting and vehicle manufacturing cost *** most of them are structural components subject to both quasi-static,dynamic and cyclic loading,the quality and quantifiable performance of the ultra-large aluminum shape castings is critical to their success in both design and *** paper briefly reviews some application examples of ultra-large aluminum castings in automotive industry and outlines their advantages and *** affecting quality,microstructure and mechanical properties of ultra-large aluminum castings are evaluated and discussed as aluminum shape casting processing is very complex and often involves many competing mechanisms,multi-physics phenomena,and potentially large uncertainties that significantly influence the casting quality and *** analysis and mechanical property assessment of an ultra-large aluminum shape casting are *** are highlighted and suggestions are made for robust design and manufacturing of ultra-large aluminum castings.

关键词： ultra-large castings aluminum light-weighting quality microstructure materials properties

Terahertz band simulations using two different radiative transfer models

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Science China Earth Sciences 2018年第10期61卷 1482-1490页

作者： Linjun PAN Daren Lü Laboratory for Middle Atmosphere and global Environment Observation Institute of Atmospheric Physics Chinese Academy of Sciences

A high-resolution dual-band terahertz(THz) radiometer was designed to measure vertical distributions of chemical elements in the middle atmosphere of the Tibetan Plateau. A forward simulation, which always should be conducted firstly for the development of a matching retrieval algorithm, has not been done before. We use two radiative transfer models, ARTS and AM, to simulate the water vapor, ozone and carbon monoxide spectra on the plateau based on the spectral design of the THz radiometer. The emission line characteristics of the three gases in this spectral band are identified. Reasons for the differences in the spectral simulations between the two models are analyzed for individual gases. The impact of several different spectral parameter settings on the simulations are evaluated through a series of sensitivity experiments. This study suggests that the ARTS is more suitable for the development of the THz radiometer retrieval algorithm. An optimal parameter setting of the ARTS for the three elements are given.

关键词： Terahertz radiation Radiometer Radiative transfer model Spectral simulation Plateau

Iceberg calving from the Antarctic Nansen Ice Shelf in April 2016 and its local impact

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Science Bulletin 2016年第15期61卷 1157-1159页

作者： Tian Li Yifan Ding Tiancheng Zhao Xiao Cheng State Key Laboratory of Remote Sensing Science College of Global Change and Earth System ScienceBeijing Normal UniversityBeijing 100875China Joint Center for global Change Studies Beijing 100875China

Owing to global warming,frequent ice shelf disintegration and rapid acceleration of inland ice flow have occurred in recent decades,which impacts the Antarctic mass balance and the global sea level[1].These events are closely linked to atmospheric and oceanic *** prolonged melt season and larger extent of melt ponds on the ice shelf surface[2],as well as enhanced basal melting caused by warmer sea water[3],will induce crevasses that

关键词：冰架南极冰山海洋环境全球变暖质量平衡浮游植物科学探险

Optimization of the pulse width and injection time in a double-pass laser amplifier

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High Power Laser Science and Engineering 2018年第4期6卷 91-97页

作者： Daewoong Park Jihoon Jeong Tae Jun Yu Department of Advanced Green Energy and Environment Handong Global University global Institute of Laser Technology Global Green Research and Development CenterHandong Global University

We have optimized the input pulse width and injection time to achieve the highest possible output pulse energy in a double-pass laser amplifier using two Nd:YAG rods. For this purpose, we have extended the Frantz–Nodvik equation by simultaneously including both spontaneous emission and pump energy variation. The effective pump energy of the flash lamp was 8.84 J for each gain medium. The energy of 1 J could be amplified to an output energy of 12.17 J with the maximum achieved extraction efficiency of 63.18% when an input pulse having a pulse width of 168 μs is sent 10 μs after the absorbed pump energy becomes the maximum value.

关键词： Frantz–Nodvik equation input pulse optimization pulse overlap pump energy variation spontaneous emission

Improving effectiveness of protection efforts in tiger source sites:Developing a framework for law enforcement monitoring using MIST

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Integrative Zoology 2010年第4期5卷 363-377页

作者： Emma J.STOKES Wildlife Conservation Society Global Conservation ProgramBronxNew YorkUSA

Wild tigers are in a critical state with an estimated population decline of more than 95%over the past *** the capacity and effectiveness of law enforcement in reducing poaching of tigers is an immediate priority to secure remaining wild populations in source *** 2008-2010,standardized patrol-based law enforcement monitoring(LEM)was established under the Tigers Forever Program across 8 key tiger sites in order to improve and evaluate law enforcement ***-based monitoring has the distinct advantage of providing regular and rapid information on illegal activities and ranger performance,although,until recently,it has received relatively little scrutiny from the conservation *** present paper outlines a framework for implementation of LEM in tiger source sites using MIST,a computerized management information system for ranger-based data *** framework addresses many of the technical,practical and institutional challenges involved in the design,implementation,sustainability and evaluation of *** of such a framework for LEM is a cost-effective strategy to improve the efficiency of law enforcement efforts,to increase the motivation of enforcement staff and to promote the accountability of law enforcement agencies in addressing threats to *** combined with independent,systematic and science-based monitoring of tigers and their prey,LEM has great potential for evaluating the effectiveness of protection-based conservation investments.

关键词： law enforcement monitoring MIST protected areas protection tigers

Microstructure and mechanical properties of lost foam cast 356 alloys

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China Foundry 2015年第3期12卷 214-221页

作者： Qi-gui Wang Materials Technology Global Powertrain Engineering General Motors Company

Microstructure and mechanical properties of lost foam cast aluminum alloys have been investigated in both primary A356(0.13% Fe) and secondary 356(0.47%). As expected, secondary 356 shows much higher content of Fe-rich intermetallic phases, and in particular the porosity in comparison with primary A356. The average area percent and size(length) of Fe-rich intermetallics change from about 0.5% and 6 μm in A356 to 2% and 25 μm in 356 alloy. The average area percent and maximum size of porosity also increase from about 0.4% and 420 μm to 1.4% and 600 μm, respectively. As a result, tensile ductility decreases about 60% and ultimate tensile strength declines about 8%. Lower fatigue strength was also experienced in the secondary 356 alloy. Low cycle fatigue(LCF) strength decreased from 187 MPa in A356 to 159 MPa in 356 and high cycle fatigue(HCF) strength also declined slightly from 68 MPa to 64 MPa.

关键词： lost foam casting aluminum alloys microstructure mechanical properties fatigue Weibull linear elastic fracture mechanics 356 alloy

Lessons from International Students’ Reaction to the 2011 Great East Japan Earthquake:The Case of the School of Engineering at Tohoku University

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International Journal of Disaster Risk Science 2013年第3期4卷 137-149页

作者： Oscar A.Gómez Graduate School of global Studies Doshisha UniversityKyoto 602-0898Japan

The objective of this study is to document the reaction of international students to the 11 March 2011 emergency in order to inform and improve disaster management strategies, both public and institutional. The study is based mainly on a questionnaire survey carried out in August 2011 and follow-up interviews with students and other stakeholders. It describes the background of Tohoku University’s School of Engineering and covers six different stages in the evolution of the emergency:(1) immediate response;(2) taking shelter in Sendai;(3) life in the city during the aftermath;(4) sheltering outside Sendai;(5) coming back;plus(6) an overview of the experience. Major findings include: the process of evacuation and safety confirmation was successful, yet the subsequent phases(2 and 3) went on mostly unmanaged;students relied mostly on secondary sources of information to make decisions, mainly family and friends of the same nationality, most of whom probably were not better informed than the students themselves. Based on the findings, suggestions for future disaster planning are advanced, as well as a discussion on the challenges of information provision during crisis.

关键词： disaster mostly Great

The Effect of Transient Eddy on Interannual Meridional Displacement of Summer East Asian Subtropical Jet

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Advances in Atmospheric Sciences 2012年第3期29卷 484-492页

作者：向洋杨修群 Institute for Climate and global Change Research School of Atmospheric Sciences Nanjing University

Using ERA-40 reanalysis daily data for the period 1958-2002, this study investigated the effect of tran- sient eddy （TE） on the interannual meridional displacement of summer East Asian subtropical jet （EASJ） by conducting a detailed dynamical diagnosis. The summer EASJ axis features a significant interannual coherent meridional displacement. Associated with such a meridional displacement, the TE vorticity forcing anomalies are characterized by a meridional dipole pattern asymmetric about the climatological EASJ axis. The TE vorticity forcing anomalies yield barotropic zonal wind tendencies with a phase meridionally lead- ing the zonal wind anomalies, suggesting that they act to reinforce further meridional displacement of the EASJ and favor a positive feedback in the TE and time-mean flow interaction. However, The TE thermal forcing anomalies induce baroclinic zonal wind tendencies that reduce the vertical shear of zonal wind and atmospheric baroclinicity and eventually suppress the TE activity, favoring a negative feedback in the TE and time-mean flow interaction. Although the two types of TE forcing tend to have opposite feedback roles, the TE vorticity forcing appears to be dominant in the TE effect on the time-mean flow.

关键词： East Asian subtropical jet transient eddy vorticity forcing transient eddy thermal forcing

Securing a future for wild Indochinese tigers:Transforming tiger vacuums into tiger source sites

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Integrative Zoology 2010年第4期5卷 324-334页

作者： Antony J.LYNAM Wildlife Conservation Society Global Conservation ProgramBronx New YorkUSA

A century ago,tigers(Panthera tigris Linnaeus,1758)were so common in parts of Southeast Asia as to be considered pests,and governments sponsored their *** loss and fragmentation,market-driven poaching and loss of prey have since led to the disappearance of Indochinese tigers from most their former *** 15 years of dedicated tiger conservation funding,national estimates of Indochinese tiger subpopulations can at best only be roughly *** future for the subspecies appears grim unless very focused efforts can be applied to stabilize and recover *** a regional scale,the 2 proposed subspecies Panthera tigris corbetti and *** jacksoni are effectively managed as separate conservation *** where to place conservation efforts should consider the vulnerability(likelihood of extinction)and irreplaceability(likelihood that an area contributes uniquely to regional conservation)of tiger *** 1 site in Thailand supporting10000 km^(2))block of dry forest habitat available in the region.A reintroduction program is the only option to recover tigers there.

关键词： conservation priorities Indochinese tigers irreplaceability threats vulnerability