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Singular Values of Sums of Positive Semidefinite Matrices

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Wuhan University Journal of Natural Sciences 2020年第4期25卷 307-310页

作者： CHEN Dongjun zhang yun School of Mathematical Sciences Huaibei Normal UniversityHuaibei 235000AnhuiChina

For positive real numbers a,b,a+b≤max{a+b1/2 a1/2,b+a1/2b1/2}.In this note,we generalize this fact to matrices by proving that for positive semidefinite matrices A and B of order n,for any c∈[-1,1]and j=1,2,…,n,sj(A+B)≤sj((A⊕B)+φc(A,B))≤sj(A+|B1/2A1/2|)⊕(B+|A1/2B1/2|),where sj(X)denotes the j-th largest singular value of X andφc(A,B):=1/2((1+c)|B1/2A1/2|(1-c)A1/2B1/2(1-c)B1/2A1/2(1+c)|A1/2B1/2|).This result sharpens some known ***,some related results are established.

关键词： singular values positive semidefinite matrices majorization unitarily invariant norms

Surface-ligand protected reduction on plasmonic tuning of one-dimensional MoO_(3−x)nanobelts for solar steam generation

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Nano Research 2020年第11期13卷 3025-3032页

作者： Xindian Li Dongyang Wang yun zhang Luntao Liu Wenshou Wang National Engineering Research Center for Colloidal Materials and School of Chemistry and Chemical Engineering Shandong UniversityJinan250100China

Sub-stoichiometric MoO_(3−x)nanostructures with plasmonic absorption via creating oxygen vacancies have attracted extensive attentions for many intriguing ***,the synthesis of one-dimensional(1D)plasmonic MoO_(3−x)nanostructures with widely tunable plasmonic absorption has remained a significant challenge because of their serious morphological destruction and phase change with increasing the concentration of oxygen *** we demonstrate a surface-ligand protected reduction strategy for the synthesis of 1D MoO_(3−x)nanobelts with tunable plasmonic absorption in a wide wavelength range from 200 to 2,500 *** glycol(PEG-400)is used as both the reductant to produce oxygen vacancies and the surface protected ligands to maintain 1D morphology during the formation process of MoO_(3−x)nanobelts,enabling the widely tunable plasmonic *** to their broad plasmonic absorption and unique 1D nanostructure,we further demonstrate the application of 1D MoO_(3−x)nanobelts as photothermal film for interfacial solar *** surface-ligand protected reduction strategy provides a new avenue for the developing plasmonic semiconductor oxides with maintained particle morphology and thus enriching their wide applications.

关键词： MoO3−x nanobelts surface-ligand protected reduction oxygen vacancies plasmonic tuning interfacial water evaporation

The Shock Wave Refraction in Supersonic Planar Mixing Layers

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Chinese Physics Letters 2013年第8期30卷 103-106页

作者： zhang yun-Long WANG Bing zhang Hui-Qiang School of Aerospace Tsinghua UniversityBeijing 100084

We analyze the shock wave refraction in a spatially developing shocked mixing layer by means of direct numerical *** regular and Mach reflections can occur depending on the relative strength of the induced shock wave over the vorticity of interacting vortex in the mixing *** stronger incident shock wave frequently refracts Mach *** shock polar diagram is used to determine the shock wave refraction ***,the vortices are deformed and compressed by the shock wave,and their vorticities are *** interaction of shock wave and coherent structure can be helpful to enhance the mixing process.

关键词： process layer shock

Deformation Mechanism in Fe_(61)Mn_(18)Si_(11)Cr_(10) Medium Entropy Alloy Under Different Strain Rates

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Acta Metallurgica Sinica(English Letters) 2021年第8期34卷 1109-1119页

作者： Shaoheng Sun yun zhang Zhiyong Xue Jiankun Lin Xiaohua Chen Institute of Advanced Materials North China Electric Power UniversityBeijing 102206China Institute of Engineering Technology University of Science and Technology BeijingBeijing 100083China State Key Laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

We introduce a non-equiatomic Fe_(61)Mn_(18)Si_(11)Cr_(10) medium entropy alloy designed by subjecting it to transformation-induced plasticity upon deformation at room temperature. Microstructure characterization carried out using scanning electron microscopy(SEM), electron backscatter diffraction(EBSD), transmission electron microscopy(TEM) and X-ray diffraction(XRD) shows a homogeneous solid solution FCC + BCC structured dual phase. Investigations on the deformation substructures at specific strain levels via EBSD reveal the deformation-induced transformations of γ→α′ and γ→ ε. The strengths, particularly yield strength, of the designed alloy are found to be higher than these of the well-studied five component FeMnNiCoCr system for the introduction of the hard phase( α′-martensite). When tensile tests are performed at different strain rates of 10^(–4)s^(-1), 10^(–3)s^(-1), 10^(–2)s^(-1), the tested material exhibits a slightly negative strain rate sensitivity and work hardening rate sensitivity.

关键词： Medium entropy alloy Dual phase Transformation-induced plasticity(TRIP)effect Strain rate

Search for d-MPs without duplicates in two-terminal multistate networks based on MPs

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Journal of Systems Engineering and Electronics 2022年第6期33卷 1332-1341页

作者： XU Bei FANG Yining BAI Guanghan zhang yun’an TAO Junyong Laboratory of Science and Technology on Integrated Logistics Support College of Intelligent Sciences and TechnologyNational University of Defense TechnologyChangsha 410073China School of General Aviation Nanchang Hangkong UniversityNanchang 330063China

The reliability evaluation of a multistate network is primarily based on d-minimal paths/cuts(d-MPs/d-MCs).However,being a nondeterminism polynomial hard(NP-hard)problem,searching for all d-MPs is a rather challenging *** existing implicit enumeration algorithms based on minimal paths(MPs),duplicate d-MP candidates may be *** extra step is needed to locate and remove these duplicate d-MP candidates,which costs significant computational *** paper proposes an efficient method to prevent the generation of duplicate d-MP candidates for implicit enumeration algorithms for ***,the mechanism of generating duplicate d-MP candidates in the implicit enumeration algorithms is ***,a direct and efficient avoiding-duplicates method is ***,an improved algorithm is developed,followed by complexity analysis and illustrative *** on the computational experiments comparing with two existing algorithms,it is found that the proposed method can significantly improve the efficiency of generating d-MPs for a particular demand level d.

关键词： reliability multistate network d-minimal path(d-MP) duplicate

DEM simulations of tote blenders for enhanced axial mixing efficiency

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Particuology 2021年第2期19卷 199-208页

作者： Fuhai Yu Zhihao Yao Guojie Chen yun zhang Yang Zheng Department of Chemistry and Chemical Engineering Jining UniversityQufu 273155China College of Chemical Engineering and Safety Binzhou UniversityBinzhou 256603China College of Horticulture and Plant Protection Yangzhou UniversityYangzhou 225009China

The mixing performance of a multi-bladed tote blender is investigated using a graphics processing unit-based discrete element method *** positioning,dimensions,and applicability of the baffles are systematically studied according to the axial mixing *** results indicate that the novel inclined multi-bladed baffles can break the symmetrical axial granular flow and introduce a more efficient convective flow into the granular mixing in the axial direction of the tote *** to the joint effects of convective mixing and asymmetrical granular flow,the axial mixing efficiency is increased by a factor of nearly *** importantly,the novel baffle placement approach exhibits excellent applicability to different operating conditions,particle shapes,and blender ***,the inclined baffles can prevent the segregation caused by shape discrepancies and improve the mixing homogeneity in the steady *** novel baffle design is promising for applications in more complex industrial blenders for achieving a high axial mixing efficiency.

关键词： Discrete element method(DEM) Tote blender Axial mixing efficiency Inclined baffles Non-spherical particles

2019 New Year Address of Zoological Research

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Zoological Research 2019年第1期40卷 1-2页

作者： yun zhang Yong-Gang Yao Kunming Institute of Zoology Chinese Academy of Sciences

At the beginning of this new year full of exciting prospects and potential,we would first like to share our exciting news that Zoological Research (ZR)is now covered by Science Citation Index Expanded (SCI-E),with full coverage to be backdated to issue 1 in *** encouraging progress demonstrates that ZR has taken a critical step on the journey to becoming one of the top journals in the field.

关键词： beginning Address exciting prospects

Role of Microalloyed Y and Gd in Improving the Corrosion Resistance of Rolled Mg-3Al-1Zn Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第6期35卷 941-947页

作者： Panpan Wang Haitao Jiang Yujiao Wang yun zhang Jingchao Tao Shanghai Key Laboratory of Materials Laser Processing and Modification and National Engineering Research Center of Light Alloy Net FormingSchool of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Institute of Engineering Technology University of Science and TechnologyBeijingBeijing 100083China

The corrosion performances of rolled AZ31 alloy with addition of Y and Gd were comparatively investigated. The corrosion rates of AZ31 alloy modified with Y and Gd were 3.3 and 3.7 mm/y immersing for 24 h in 3.5 wt% NaCl solution, respectively, which were much lower than that of AZ31 alloy(23.6 mm/y). The remarkable improvement in corrosion performance by adding Y or Gd was ascribed to preferentially form less noble Al_(2)Y or Al_(6)GdMn_(6) and more protective corrosion product layer, resulting in the reduction in H_(2) evolution rate and the enhancement of passivity.

关键词： AZ31 alloy Second phases Volta potential diff erence Y Gd

Failure analysis of unmanned autonomous swarm considering cascading effects

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Journal of Systems Engineering and Electronics 2022年第3期33卷 759-770页

作者： XU Bei BAI Guanghan zhang yun’an FANG Yining TAO Junyong Laboratory of Science and Technology on Integrated Logistics Support College of Intelligent Sciences and TechnologyNational University of Defense TechnologyChangsha 410073China School of General Aviation Nanchang Hangkong UniversityNanchang 330063China

In this paper, we focus on the failure analysis of unmanned autonomous swarm(UAS) considering cascading effects. A framework of failure analysis for UAS is *** by the framework, the failure analysis of UAS with crash fault agents is performed. Resilience is used to analyze the processes of cascading failure and self-repair of UAS. Through simulation studies, we reveal the pivotal relationship between resilience, the swarm size, and the percentage of failed *** simulation results show that the swarm size does not affect the cascading failure process but has much influence on the process of self-repair and the final performance of the *** results also reveal a tipping point exists in the swarm. Meanwhile, we get a counter-intuitive result that larger-scale UAS loses more resilience in the case of a small percentage of failed individuals, suggesting that the increasing swarm size does not necessarily lead to high resilience. It is also found that the temporal degree failure strategy performs much more harmfully to the resilience of swarm systems than the random failure. Our work can provide new insights into the mechanisms of swarm collapse, help build more robust UAS, and develop more efficient failure or protection strategies.

关键词： unmanned autonomous swarm(UAS) failures analy-sis cascading failure resilience