检索结果-南通市图书馆

An Extended Two-Step Method for Inverse Eigenvalue Problems with Multiple Eigenvalues

在线全文

学校读者我要写书评

暂无评论

Numerical Mathematics(Theory,Methods and Applications) 2023年第4期16卷 968-992页

作者： Yue Wang weiping shen School of Mathematical Sciences Zhejiang Normal UniversityJinhuaP.R.China

In recent years,numerical solutions of the inverse eigenvalue problems with multiple eigenvalues have attracted the attention of some researchers,and there have been a few algorithms with quadratic *** propose here an extended two-step method for solving the inverse eigenvalue problems with multiple *** appropriate assumptions,the convergence analysis of the extended method is presented and the cubic root-convergence rate is *** experiments are provided to confirm the theoretical results and comparisons with the inexact Cayley transform method are *** extended method and convergence result in the present paper may enrich the results of numerical solutions of the inverse eigenvalue problems with multiple eigenvalues.

关键词： Inverse eigenvalue problems extended two-step method cubic root-convergence

Thermoelectric properties of p-type (Bi_(0.15)Sb_(0.85))_2Te_3-PbTe graded thermoelectric materials with different barriers

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2005年第4期12卷 347-350页

作者： Guiying Xu Yanping Gao Changchun Ge weiping shen Laboratory of Special Ceramics and Powder Metallurgy University of Science and Technology Beijing Beijing 100083 China

The p-type （Bi0.15Sb0.85）2Te3 and PbTe are typical thermoelectric materials used for low and middle temperature range and functional graded materials （FGM） is an inevitable way to widen the working temperature range. Here two segments graded thermoelectric materials （GTM） consisting of （Bi0.15Sb0.85）2Te3, PbTe and different barriers were fabricated by the common hot pressure method. Metals Fe, Mg and Ni were used as barriers between the two segments. The diffusion of different barriers between the barriers and bases were analyzed by electron microprobe analysis （EMA）. The phase and crystal structures were determined by X-ray diffraction analysis （XRD）. The thermoelectric properties were measured at 303 K along the direction parallel to the pressing direction. The results show that the compositional diffusion occurs when there is no barrier at the interface of the two segments, and the diffusion of Pb is most obvious; as the barrier material, the diffusion of metals Fe, Mg and Ni between different bases is not very obvious, and the thermoelectric properties of GTM is much better than that of the original segment.

关键词： thermoelectric parameter graded materials barrier

Comparative study of β-Si_3N_4 powders prepared by SHS sintered by spark plasma sintering and hot pressing

在线全文

学校读者我要写书评

暂无评论

Journal of University of Science and Technology Beijing 2007年第3期14卷 271-275页

作者： Ling Bai Xiaodong Mao weiping shen Changchun Ge Laboratory of Special Ceramics and Powder Metallurgy University of Science and Technology Beijing Beijing 100083 China

β-Si3N4 powders prepared by self-propagating high-temperature synthesis （SHS） with additions of Y2O3 and Al2O3 were sintered by spark plasma sintering （SPS）. The densification, microstructure, and mechanical properties of Si3N4 ceramics prepared using this method were compared with those obtained by hot pressing process. Well densified Si3N4 ceramics with finer and homogeneous microstructure and better mechanical properties were obtained in the case of the SPS technique at 200°C lower than that of hot pressing. The microhardness is 15.72 GPa, the bending strength is 716.46 MPa, and the fracture toughness is 7.03 MPa·m1/2.

关键词： self-propagating high-temperature synthesis (SHS) hot pressing spark plasma sintering (SPS) silicon nitride mechanicalproperties

ANTIPLANE CIRCULAR INCLUSION WITH A CURVED CRACK CROSSING THE BOUNDARY

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2000年第3期13卷 271-276页

作者： Lu Jianfei Wang Jianhua shen weiping Shanghai Jiao Tong Univ Civil Engn & Mech Coll Shanghai 200030 Peoples R China

The weakly singular integral equation sued to solve the problem ofthe curved crack crossing the boundary of the antiplane circularinclusion is presented. Using the principal part analysis method ofthe Cauchy type integral equation, the singular stress index at theintersection and the singular stress of angular Regions near theintersection are obtained. By using the singular stress obtained, thestress intensity factor at The intersection is defined. After thenumerical solution of the integral equation, the stress intensityfactors at The end points of the crack and intersection areobtainable.

关键词： antiplane circular inclusion curved crack stress intensity factor

Bonding Interface of W-CuCrZr Explosively Welded Composite Plates for Plasma Facing Components

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2014年第12期30卷 1230-1234页

作者： Congxiao Sun Shuming Wang Wenhao Guo weiping shen Changchun Ge Department of Materials Science and Engineering University of Science & Technology Beijing

In order to realize the effective jointing of tungsten and Cu Cr Zr alloys manufactured for plasma facing components（PFCs）, explosive welding is employed for its some unique advantages. Different welding characteristics were investigated in this study. The interfacial waveform of the welded plates changed periodically from flat-wavelet to a large wave and finally to a stable wave, which began with the detonation point. The bonding strength of the specimens is higher than 32.9 MPa. Welding hardening and the formation of microcracks occurred at the interface zone. The results demonstrate that the joining reliabilities need to be improved in order to meet the need of applications involving the use of explosive welding to fabricate tungsten-based PFCs.

关键词： Explosive welding W-CuCrZr Interfacial waveform Plasma facing components Bonding strength

The Impacts and Implications of the COVID-19 Pandemic on the Global Response to Climate Change

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Urban and Environmental Studies 2021年第2期9卷 6-20页

作者： CHEN Ying shen weiping Research Institute for Ecological Civilization Chinese Academy of Social Sciences University of Chinese Academy of Social Sciences

The coronavirus disease(COVlD-19) pandemic has posed the most severe impact on the global economy and society since World War Ⅱ.The pandemic has brought into focus how climate change is related with virus transmission and health,and has made the global transition toward low-carbon development more difficult and challenged the implementation of the Paris *** the pandemic has significantly reduced carbon emissions and improved the environmental quality in the short term,it is still an unwanted event in the process of pursuing sustainable development;although objectively the pandemic has weakened countries ’ efforts in terms of policies and actions to address climate change,the restructuring of global value chains in the post-COVlD era has also brought new opportunities for a transition toward green and low-carbon development;although the pandemic has warned people of how important resilient governance and international cooperation is to addressing the crisis,the global climate governance process has come to a complete standstill since the outbreak of COVID-19,attenuating the mutual trust among countries and disabling the leadership in climate *** pandemic is a preview of the climate crisis,and it is important to learn from it for a better *** quickly contained the pandemic within the country,actively resumed work and production,and gained a first-mover advantage in economic *** should maintain strategic focus when pursuing ecological development,enhance the resilience of the socio-economic system,seize the opportunity of transitioning toward low-carbon development by turning the crisis into opportunities,and promote high-quality development within the country while fully engaging in global climate governance to seek ecological progress with other countries.

关键词： The COVID-19 pandemic climate change low-carbon transition climate governance.

THE INTERACTION BETWEEN MULTIPLE CURVED RIGID LINE AND ANTIPLANE CIRCULAR INCLUSION

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2000年第2期13卷 119-124页

作者： Lu Jianfei Zhang Xiaofang Wang Jianhua shen weiping Dept.of Civil Eng.and Mechanics Shanghai Jiaotong Univ.Shanghai 200030China Dept.of Physics and Mathematics Jiangshu University of Science and TechnologyZhengjiang 212013China

The interaction between multiple curved rigid line and circular inclusion in antiplane loading condition is considered in this paper. By utilizing the point force elementary solutions and taking density function of traction difference along curved rigid lines, a group of weakly singular integral equations with logarithmic kernels can be obtained. After the numerical solution of the integral equations, the discrete values of density functions of traction difference are obtainable. So the stress singularity coefficient at rigid line tips can be calculated, and two numerical examples are given.

关键词： antiplane curved rigid line circular inclusion stress singularity coefficient

Densification,microstructure,and fracture behavior of TiC/Si_3N_4 composites by spark plasma sintering

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2008年第3期27卷 315-319页

作者： BAI Ling GE Changchun shen weiping MAO Xiaodong ZHANG Ke Laboratory of Special Ceramics and Powder Metallurgy University of Science and Technology Beijing Beijing 100083 China

TiC/Si3N4 composites were prepared using the β-Si3N4 powder synthesized by self-propagating high-temperature synthesis （SHS） and 35 wt.% TiC by spark plasma sintering. Y2O3 and Al2O3 were added as sintering additives. The almost full sintered density and the highest fracture toughness （8.48 MPa·m1/2） values of Si3N4-based ceramics could be achieved at 1550℃. No interfacial interactions were noticeable between TiC and Si3N4. The toughening mechanisms in TiC/Si3N4 composites were attributed to crack deflection, microcrack toughening, and crack impedance by the periodic compressive stress in the Si3N4 matrix. However, increasing microcracks easily led to excessive connection of microcracks, which would not be beneficial to the strength.

关键词： silicon nitride titanium carbide spark plasma sintering (SPS) microstructure fracture behavior

Effects of Recycled Aggregate Content on Pervious Concrete Performance

在线全文

学校读者我要写书评

暂无评论

Journal of Renewable Materials 2020年第12期8卷 1711-1727页

作者： Lei Guo Zi Guan Lixia Guo weiping shen Zhilong Xue Pingping Chen Mingru Li School of Water Conservancy North China University of Water Resources and Electric PowerZhengzhou450046China Henan Water Valley Research Institute Zhengzhou450046China Henan Key Laboratory of Water Environment Simulation and Treatment Zhengzhou450002China

A recycled aggregate(RA)was prepared by crushing and sieving demolished discarded concrete pavements and was subsequently tested and analyzed to determine its various physical *** this basis,pervious concrete(PC)mix proportions were *** RA particles with sizes of 5–10 and 10–20 mm were *** specimens were prepared with a water–cement ratio of 0.3,an aggregate–cement ratio of 4.5,the substitute rates of RA with 0,25%,50%,75%and a single-/double-gap-graded RA mix(mass ratio of particles with sizes of 5–10 mm to particles with sizes of 10–20 mm:1:1,1:2,2:1,2:3 and 3:2).Various properties of the RA-containing PC(RPC)were determined by analyzing the compressive strength,splitting tensile strength,effective porosity,permeation coefficient and impact and abrasion resistance of the *** results showed the following:The density of the RPC decreased with an increasing RA replacement *** density of the RPC prepared with a double-gapgraded RA mix was lower than that prepared with a single-gap-graded RA(particle size:10–20 mm)*** permeation coefficient of the RPC increased with increasing *** splitting tensile strength of the RPC was positively correlated with its compressive *** compressive strength of the RPC decreased with increasing *** regression analysis showed that the impact and abrasion resistance of the RPC increased with increasing compressive *** addition,all of the RPC specimens met the strength and permeation require*** study can provide theoretical support for the application of RPC.

关键词： Recycled aggregate recycled pervious concrete strength permeability wear resistance mix proportion