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Indentation behavior of a semi-infinite piezoelectric semiconductor under a rigid flat-ended cylindrical indenter

Applied Mathematics and Mechanics(English Edition) 2024年第4期45卷 649-662页

作者： Shijing GAO Lele zhang Jinxi LIU Guoquan NIE Weiqiu CHEN State Key Laboratory of Mechanical Behavior and System Safety of Traffic Engineering Structures Shijiazhuang Tiedao UniversityShijiazhuang 050043China School of Mechanical Engineering Shijiazhuang Tiedao UniversityShijiazhuang 050043China Hebei Key Laboratory for Mechanics of Intelligent Materials and Structures Department of Engineering MechanicsShijiazhuang Tiedao UniversityShijiazhuang 050043China State Key Laboratory of Computer Aided Design and Computer Graphics Key Laboratory of Soft Machines and Smart Devices of Zhejiang ProvinceDepartment of Engineering MechanicsZhejiang UniversityHangzhou 310027China

This paper theoretically studies the axisymmetric frictionless indentation of a transversely isotropic piezoelectric semiconductor(PSC)half-space subject to a rigid flatended cylindrical *** contact area and other surface of the PSC half-space are assumed to be electrically *** the Hankel integral transformation,the problem is reduced to the Fredholm integral equation of the second *** equation is solved numerically to obtain the indentation behaviors of the PSC half-space,mainly including the indentation force-depth relation and the electric potential-depth *** results show that the effect of the semiconductor property on the indentation responses is limited within a certain range of variation of the steady carrier *** dependence of indentation behavior on material properties is also analyzed by two different kinds of *** element simulations are conducted to verify the results calculated by the integral equation technique,and good agreement is demonstrated.

关键词： piezoelectric semiconductor(PSC) insulating indenter electromechanical response singular integral equation finite element simulation

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Migration Behavior of Impurity Iron in Silicon Melt Under Pulsed Electric Current

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Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 889-903页

作者： Mengcheng Zhou Yaxiong Dai Changhao Liu Shengli Ding Xinfang zhang School of Metallurgical and Ecological Engineering University of Science and Technology BeijingBeijing 100083China Guangdong Zhongnan Iron&Steel Co. Ltd.Guangdong 512123China

The impurity iron in silicon material will seriously affect the photoelectric conversion efficiency of silicon solar ***,the traditional silicon purification method has the disadvantages of long cycle,high energy consumption and serious *** this study,an efficient and green pulsed electric current purification technology is *** electromigration effect of iron elements,the current density gradient driving of iron phase,and the gravity of iron phase all affect the migration behavior of iron phase in silicon melt under pulsed electric *** of the depth of electrode insertion into the silicon melt,the solubility of iron in silicon decreases under the pulsed electric current,which helps to form the iron *** the same time,the iron phase tends to sink toward the bottom under the influence of *** the electrode is shallowly inserted,a non-uniform electric field is formed in the silicon melt,and the iron phase is mainly driven by the current density gradient to accelerate sink toward the *** the electrode is fully inserted,an approximately uniform electric field is formed in the silicon melt,and iron elements are preferentially migrated to the cathode by electromigration,forming iron phase sinking at the *** study of impurity iron migration behavior in silicon melt under pulsed electric current provides a new approach for the purification of polycrystalline silicon.

关键词： Metallurgical silicon Pulsed electric current Iron-rich phase Current density gradient Electromigration

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A dual-mode optical thermometer based on dual-excitation Bi^(3+),Sm^(3+)co-doped Y_(4)GeO_(8) phosphors

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Journal of Rare Earths 2024年第8期42卷 1437-1446,I0002页

作者： Danyu zhang Yuxuan Luo Junyu Chen Lianjie Li Hai Guo Department of Physics Zhejiang Normal UniversityJinhua321004China

Dual-excitation and dual-emission Y_(4)GeO_(8):Bi^(3+),Sm^(3+)phosphors were manufactured by traditional solidphase sintering *** X-ray diffraction,morphology,photoluminescence,energy transfer process and temperature sensing properties of Y_(4)GeO_(8):Bi^(3+),Sm^(3+)samples were comprehensively *** Y4GeO_(8):Bi^(3+),Sm^(3+)phosphors exhibit characteristic emissions of Bi^(3+)(^(3)P_(1)→^(1)S_(0)) and Sm^(3+)(^(4)G_(5/2)→^(6)H)under both 290 and 347 nm *** fluorescence intensity ratio and Commission International de L'Eclairage coordinates modes,Y_(4)GeO_(8):Bi^(3+),Sm^(3+)samples present excellent temperature measurement *** maximum relative sensitivity(S_(r-max)) values of the former are 1.55%/K(460 K,290 nm excitation) and 0.82%/K(506 K,347 nm excitation).The S_(r-max)(x) values of the latter are 0.21 %/K(437 K,290 nm excitation) and 0.15%/K(513 K,347 nm excitation).These results illustrate that Y_(4)GeO_(8):Bi^(3+),Sm^(3+)phospho rs can be used as a candidate material for a dual-mode optical thermometer under dual-excitation.

关键词： Dual-mode optical thermometer Luminescent properties Y_(4)GeO_(8):Bi^(3+) Sm^(3+)phosphors Rare earths

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有限元法分析老年骨质疏松患者L_(3/4)椎板减压椎间融合的力学性能

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中国组织工程研究 2024年第6期28卷 847-851页

作者：张敏彭婧张强陈德旺南昌市洪都中医院江西省南昌市330000

背景:老年骨质疏松患者同时罹患高位腰椎间盘突出的发病人数逐年增加,行常规后入路椎板减压及椎间融合术后腰椎整体力学强度及邻近椎体的生物力学性能改变尚未明确。有限元分析方法以其无创、可重复性高、结果精确等优势在生物力学领域... 详细信息

背景:老年骨质疏松患者同时罹患高位腰椎间盘突出的发病人数逐年增加,行常规后入路椎板减压及椎间融合术后腰椎整体力学强度及邻近椎体的生物力学性能改变尚未明确。有限元分析方法以其无创、可重复性高、结果精确等优势在生物力学领域具有重要价值。目的:基于有限元分析方法,针对老年骨质疏松患者的特定人群,建立L_(3/4)椎板减压椎间融合的有限元模型,评估弯腰动作下骨骼内固定复合体的生物力学情况。方法:利用Mimics 21.0提取脊柱CT的DICOM数据建立腰椎(T_(12)-L_(5))三维骨性结构,导入Geomagic wrap 2017,通过重划网格、删除钉状物、剪切模型、填充空洞、探测并编辑轮廓线、构造曲面片及格栅、拟合曲面等操作建立L_(3/4)全椎板减压模型。利用Solidworks 2017构建椎弓根螺钉、连接杆、椎间融合器,将其组装于L_(3/4)全椎板减压模型,通过拉伸、等距曲面、移动与复制实体等操作建立椎间盘、关节突软骨等结构。应用ANSYS Workbench 17.0进行材料赋值、模拟脊柱韧带、网格划分、施加作用力及限定边界条件,建立完整骨质疏松性L_(3/4)椎板减压及椎间融合脊柱有限元模型。观察弯腰工况下L_(3/4)椎板减压及椎间融合全腰椎有限元模型的应力、应变及位移云图。结果与结论:(1)应力云图方面:T_(12)-L_(1)椎体平均应力值最高,L_(2)下降24%,L_(3)下降55%,L_(4-5)下降约80%;L_(4/5)关节突区域应力集中程度最高,L_(2/3)次之,L_(1/2)及T_(12)/L_(1)程度轻;螺钉与连接杆交界处应力集中明显,螺钉在椎弓根进出口处次之;(2)应变与位移云图方面:L_(4/5)及L_(2/3)关节突的应变程度最高,T_(12)/L_(1)及L_(1/2)的应变程度次之,L_(3/4)节段融合器、椎弓根螺钉及连接杆无任何可见变形;各节段椎间盘均出现较大变形;(3)提示多软件协同操作可顺利构建老年骨质疏松性L_(3/4)椎板减压及椎间融合脊柱有限元模型;老年腰椎术后患者可耐受前屈动作,证实L_(3/4)椎板减压及椎间融合能够维持脊柱形态并保证脊柱稳定性,但是需警惕胸腰椎应力性骨折及邻椎病的发生。

关键词：腰椎模型骨质疏松椎板减压椎间融合有限元模型生物力学

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Highly Flexible Graphene-Film-Based Rectenna for Wireless Energy Harvesting

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Energy & Environmental Materials 2024年第2期7卷 320-325页

作者： jingwei zhang Yuchao Wang Rongguo Song Zongkui Kou Daping He Hubei Engineering Research Center of RF-Microwave Technology and Application School of ScienceWuhan University of TechnologyWuhan 430070China Sanya Science and Education Innovation Park of Wuhan University of Technology Sanya 572000China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China

Herein,we report the design,fabrication,and performance of two wireless energy harvesting devices based on highly flexible graphene macroscopic films(FGMFs).We first demonstrate that benefiting from the high conductivity of up to 1×10^(6)S m^(-1)and good resistive stability of FGMFs even under extensive bending,the FGMFs-based rectifying circuit(GRC)exhibits good flexibility and RF-to-DC efficiency of 53%at 2.1 ***,we further expand the application of FGMFs to a flexible wideband monopole rectenna and a 2.45 GHz wearable rectenna for harvesting wireless *** wideband rectenna at various bending conditions produces a maximum conversion efficiency of 52%,46%,and 44%at the 5th Generation(5G)2.1 GHz,Industrial Long-Term Evolution(LTE)2.3 GHz,and Scientific Medical(ISM)2.45 GHz,respectively.A 2.45 GHz GRC is optimized and integrated with an AMC-backed wearable *** proposed 2.45 GHz wearable rectenna shows a maximum conversion efficiency of 55.7%.All the results indicate that the highly flexible graphene-film-based rectennas have great potential as a wireless power supplier for smart Internet of Things(loT)applications.

关键词： flexible rectennas highly flexible graphene-based films wireless energy harvesting

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Resource-saving scheduling scheme for centralized target tracking in multiple radar system under automatic blanket jamming

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Chinese Journal of Aeronautics 2024年第5期37卷 349-362页

作者： Zhengjie LI Yujie WEI Junwei XIE Haowei zhang Yu TIAN Air and Missile Defense College Air Force Engineering UniversityXi’an 710051China Air Force Xi’an Flying College Xi’an 710300China Air and Missile Defense Institute Air Force Research InstituteBeijing 100085China School of Economics and Management Beihang UniversityBeijing 100191China

This paper investigates the problem of Joint Radar Node Selection and Power Allocation(JRNSPA)in the Multiple Radar System(MRS)in the blanket jamming *** radar node independently tracks moving target and subsequently transmits the raw observation data to the fusion center,which formulates a centralized tracking network *** order to establish a practical blanket jamming environment,we suppose that each target carries the self-defense jammer which automatically implements blanket jamming to the radar nodes that exceed the preset interception ***,the Predicted Conditional Cramer-Rao Lower Bound(PC-CRLB)is derived and utilized as the tracking accuracy *** at ensuring both the tracking performance and the Low Probability of Intercept(LPI)performance,the resource-saving scheduling model is formulated to minimize the transmit power consumption while meeting the requirements of tracking ***,the Modified Zoutendijk Method Of Feasible Directions(MZMFD)-based two-stage solution technique is adopted to solve the formulated non-convex optimization *** results show the effectiveness of the proposed JRNSPA scheme.

关键词： Multiple Radar System(MRS) Centralized target tracking Resource scheduling Blanket jamming Low Probability of Intercept(LPI)

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Cooperative decision-making algorithm with efficient convergence for UCAV formation in beyond-visual-range air combat based on multi-agent reinforcement learning

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Chinese Journal of Aeronautics 2024年第8期37卷 311-328页

作者： Yaoming ZHOU Fan YANG Chaoyue zhang Shida LI Yongchao WANG School of Aeronautic Science and Engineering Beihang UniversityBeijing 100191China Key Laboratory of Industrial Control Technology Institute of Cyber-Systems and ControlZhejiang UniversityHangzhou 310027China

Highly intelligent Unmanned Combat Aerial Vehicle(UCAV)formation is expected to bring out strengths in Beyond-Visual-Range(BVR)air *** Multi-Agent Reinforcement Learning(MARL)shows outstanding performance in cooperative decision-making,it is challenging for existing MARL algorithms to quickly converge to an optimal strategy for UCAV formation in BVR air combat where confrontation is complicated and reward is extremely sparse and *** to solve this problem,this paper proposes an Advantage Highlight Multi-Agent Proximal Policy Optimization(AHMAPPO)***,at every step,the AHMAPPO records the degree to which the best formation exceeds the average of formations in parallel environments and carries out additional advantage sampling according to ***,the sampling result is introduced into the updating process of the actor network to improve its optimization ***,the simulation results reveal that compared with some state-of-the-art MARL algorithms,the AHMAPPO can obtain a more excellent strategy utilizing fewer sample episodes in the UCAV formation BVR air combat simulation environment built in this paper,which can reflect the critical features of BVR air *** AHMAPPO can significantly increase the convergence efficiency of the strategy for UCAV formation in BVR air combat,with a maximum increase of 81.5%relative to other algorithms.

关键词： Unmanned combat aerial vehicle(UCAV)formation Decision-making Beyond-visual-range(BVR)air combat Advantage highlight Multi-agent reinforcement learning(MARL)

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Dissolution behavior of Al_(2)O_(3)inclusions into CaO-MgO-SiO_(2)-Al_(2)O_(3)-TiO_(2)system ladle slags

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International Journal of Minerals,Metallurgy and Materials 2024年第5期31卷 977-987页

作者： Zhiyin Deng Xiaomeng zhang Guangyu Hao Chunxin Wei Miaoyong Zhu Key Laboratory for Ecological Metallurgy of Multimetallic Mineral(Ministry of Education) Northeastern UniversityShenyang 110819China School of Metallurgy Northeastern UniversityShenyang 110819China TBEA Shenyang Transformer Group Co. Ltd.Shenyang 110141China Angang Steel Co. Ltd.Anshan 114021China

To investigate the dissolution behaviors of Al_(2)O_(3)inclusions in CaO-5wt%MgO-SiO_(2)-30wt%Al_(2)O_(3)-TiO_(2)system ladle slags,confocal scanning laser microscopy was conducted on the slags with different TiO_(2)contents(0-10wt%),and scanning electron microscopy was performed to study the interfacial reaction between Al_(2)O_(3)and this slag *** results disclose that the dissolution of Al_(2)O_(3)inclusions does not result in the formation of new phases at the boundary between the slag and the *** TiO_(2)-bearing and TiO_(2)-free ladle slags,there is no difference in the dissolution mechanism of Al_(2)O_(3)inclusions at steelmaking *** layer diffusion is found as the controlling step of the dissolution of Al_(2)O_(3),and the diffusion coefficient is in the range of 4.18×10^(-10)to 2.18×10^(-9)m^(2)/s at 1450-1500℃.Compared with the solubility of Al_(2)O_(3)in the slags,slag viscosity and temperature play a more profound role in the dissolution of Al_(2)O_(3)inclusions.A lower viscosity and a lower melting point of the slags are beneficial for the *** addition of TiO_(2)(e.g.,5wt%)in ladle slags can enhance the dissolution of Al_(2)O_(3)inclusions because of the low viscosity and melting point of the slags,while excessive addition of TiO_(2)(e.g.,10wt%)shows the opposite trend.

关键词： inclusions dissolution ladle refining slag titanium dioxide confocal scanning laser microscopy

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Straw return decreases polycyclic aromatic hydrocarbon (PAH) accumulation in winter wheat and human health risk by enhancing PAH dissipation in rhizosphere soil

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Pedosphere 2024年第4期34卷 699-708页

作者： Jun CAI He zhang Xiangyao WU Yifan LIU Yunmei WU Jinfeng WANG Chuangye zhang Benhua SUN Fuyong WU College of Natural Resources and Environment Northwest A&F UniversityYangling 712100China Key Laboratory of Plant Nutrition and the Agri-environment in Northwest China Ministry of AgricultureYangling 712100China

Straw return in situ,a common agronomic measure in China,has been widely used not only to increase crop yields and improve soil nutrients but also to remove polycyclic aromatic hydrocarbons(PAHs)from agricultural ***,the safety risks of food crops(i.e.,human health risk of wheat grains)grown in PAHs-contaminated agricultural soils amended with crop straw remain uncertain.A pot experiment was conducted in a PAHs-contaminated agricultural soil cultivated with winter wheat under different ratios of corn straw addition(0%(control,CK),1%,2.5%,and 5%,weight/weight).Results showed that corn straw addition significantly(P<0.05)decreased PAH concentrations in rhizosphere soil,roots,straws,and grains by 48.32%–50.01%,11.85%–42.67%,9.78%–28.03%,and 14.16%–31.67%,respectively,compared with CK,whereas the transfer factors of PAHs from roots to straws were significantly(P<0.05)increased.A correlation heatmap showed that PAH concentrations in roots,straws,and grains were positively(P<0.01)correlated with those in rhizosphere *** indicated that corn straw decreased PAH accumulation in winter wheat due to the increase of PAH dissipation in the rhizosphere soil,although it enhanced PAH transfer in winter *** incremental lifetime cancer risk(ILCR)model indicated that corn straw significantly(P<0.05)decreased the human health risk of winter wheat grains by 29.73%–45.05%.Overall,corn straw apparently reduced PAH accumulation in winter wheat,ecological risk,and human health risk via enhancing PAH dissipation in the rhizosphere *** findings provide an important scientific basis and theoretical guidance for agricultural safety production.

关键词： corn straw addition ecological risk food crops incremental lifetime cancer risk transfer factor

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Subsoil tillage enhances wheat productivity,soil organic carbon and available nutrient status in dryland fields

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Journal of Integrative Agriculture 2024年第1期23卷 251-266页

作者： Qiuyan Yan Linjia Wu Fei Dong Shuangdui Yan Feng Li Yaqin Jia Jiancheng zhang Ruifu zhang Xiao Huang Institute of Wheat Research Shanxi Agricultural UniversityLinfen 041000China State Key Laboratory of Sustainable Dryland Agriculture(in preparation) Shanxi Agricultural UniversityTaiyuan 030031China College of Resources and Environment Shanxi Agricultural UniversityTaigu 030801China Jiangsu Key Lab and Engineering Center for Solid Organic Waste Utilization National Engineering Research Center for Organicbased FertilizersNanjing Agricultural UniversityNanjing 210095China

Tillage practices during the fallow period benefit water storage and yield in dryland wheat ***,there is currently no clarity on the responses of soil organic carbon(SOC),total nitrogen(TN),and available nutrients to tillage practices within the growing *** study evaluated the effects of three tillage practices(NT,no tillage;SS,subsoil tillage;DT,deep tillage)over five years on soil physicochemical *** samples at harvest stage from the fifth year were analyzed to determine the soil aggregate and aggregate-associated C and N *** results indicated that SS and DT improved grain yield,straw biomass and straw carbon return of wheat compared with *** contrast to DT and NT,SS favored SOC and TN concentrations and stocks by increasing the soil organic carbon sequestration rate(SOCSR)and soil nitrogen sequestration rate(TNSR)in the 0-40 cm *** SOC levels under SS and NT were associated with greater aggregate-associated C fractions,while TN was positively associated with soluble organic nitrogen(SON).Compared with DT,the NT and SS treatments improved soil available nutrients in the 0-20 cm *** findings suggest that SS is an excellent practice for increasing soil carbon,nitrogen and nutrient availability in dryland wheat fields in North China.

关键词： tillage dryland wheat fields soil aggregate size soil nutrients soil carbon and nitrogen fractions

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