检索结果-南通市图书馆

维普期刊数据库

Characterization and degradation of β-Sn particles in thermal aged Pb-rich solder joint for low-temperature co-fired ceramic(LTCC) applications

在线全文

学校读者我要写书评

暂无评论

Rare Metals 2024年第10期43卷 5346-5361页

作者： Jin-Hong Liu Zhe Zhu qiang-qiang Nie Jun-Fu Liu Peng He Shu-Ye Zhang State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Anhui Key Laboratory of Microsystem East China Research Institute of Microelectronics School of Materials Science and Engineering Hefei University of Technology

High-lead solder joints are still playing an indispensable role in military and space ***, in-depth characterization of high-lead solder joints and the underlying degradation mechanisms remain unexplored. This research first performed aging tests on Sn10Pb90 solder joints, the shear strength at room and elevated temperatures gradually reduced, and the resistance increased. Here, a two-layered Ni–Sn intermetallic compound(IMC) structure was identified using transmission electron microscopy(TEM), which could be attributed to the change of Sn content in the solder. Moreover, the internal annealing twin of a Sn particle was discovered,which could be attributed to creeping induced by thermal expansion coefficient(CTE) difference between Sn and *** analysis of partial and whole annealing twins was conducted through high-resolution TEM(HRTEM).Finally, four degradation mechanisms were *** of the IMC layer would result in increased brittleness and resistivity. For particle coarsening, apart from diminishing the ductility and toughness of the solder joint, it would also accelerate the creeping rate by weakening the phase boundary strength. Regarding voids and cracks induced by phase boundary sliding, wedgeshaped cracking and pore-shaped cracking were discovered and their formation was analyzed. Most importantly, the consumption of Sn resulted in a depletion of wettable layer,leading to the formation of Pb streams and isolated IMC islands, also known as the spalling and delamination of IMCs. Pb diffusion followed a spiral path, which was mutually influenced by orientation misfit and concentration gradient. A technique to prevent cracking was *** research is expected to provide significant technical references for high-lead solder joints.

关键词： Aging Degradation mechanisms High-lead solder joints Properties TEM characterization

New direction for surgery:Super minimally invasive surgery

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2024年第12期30卷 1676-1679页

作者： En-qiang Linghu Department of Gastroenterology First Medical Center of Chinese PLA General HospitalBeijing 100853China

The top goal of modern medicine is treating disease without destroying organ structures and making patients as healthy as they were before their *** invasive surgery(MIS)has dominated the surgical realm because of its lesser ***,changes in anatomical structures of the body and reconstruction of internal organs or different organs are common after traditional surgery or MIS,decreasing the quality of life of patients ***,I propose a new treatment mode,super MIS(SMIS),which is defined as“curing a disease or lesion which used to be treated by MIS while preserving the integrity of the organs”.In this study,I describe the origin,definition,operative channels,advantages,and future perspectives of SMIS.

关键词： Super minimally invasive surgery Minimally invasive surgery Treatment mode Traditional Surgery New direction for surgery

Current understanding of ELF4 deficiency:a novel inborn error of immunity

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Pediatrics 2024年第5期20卷 444-450页

作者： Hong-qiang Du Xiao-Dong Zhao Department of Rheumatology&Immunology National Clinical Research Center for Child Health and DisordersMinistry of Education Key Laboratory of Child Development and DisordersChongqing Key Laboratory of Child Rare Diseases in Infection and ImmunityChildren’s Hospital of Chongqing Medical UniversityZhongshan Er Road 136Yuzhong DistrictChongqingChina

Background ELF4 deficiency has been recently recognized as a novel disorder within the spectrum of inborn errors of immunity(IEIs),specifically categorized as a“disease of immune dysregulation.”Cases of this condition,reported by our team and others,are very limited *** such,our current knowledge of this new disease remains *** review aims to provide a brief overview of the clinical manifestations,pathogenesis,and treatment strategies for this novel *** sources A comprehensive review was conducted after an extensive literature search in the PubMed/Medline database and websites concerning transcriptional factor ELF4 and reports concerning patients with ELF4 *** search strategy was“ELF4 OR ETS-related transcription factor Elf-4 OR EL4-like factor 4 OR myeloid Elf-1-like factor”as of the time of manuscript *** The current signature manifestations of ELF4 deficiency disorder are recurrent and prolonged oral ulcer,abdominal pain,and diarrhea in pediatric *** some cases,immunodeficiency and autoimmunity can also be *** Sanger sequencing or whole exome sequencing can be used to detect variation in ELF4 *** blotting for ELF4 expression of the patient’s cells can confirm the pathogenic effect of the *** fully confirm the pathogenicity of the variant,further functional test is strongly *** and biologics are the mainstream management of ELF4 deficiency *** Pediatric males presenting with recurring ulcerations in digestive tract epithelium with or without recurrent fever should be suspected of *** atypical presentations are prominent,variations in ELF4 gene should be carefully evaluated functionally due to the complex nature of ELF4 *** of treating DEX includes use of glucocorticoid and biologics and more precise treatment needs more patients to identify and further mechanistic study.

关键词： ELF4 transcription factor Immune dysregulation Inborn errors of immunity Mechanism Recurrent infections

Effect of MgO-Cr_(2.O_(3) and Mg0-MgAl_(2.0_(4)-based refractories on refractory-steel interface reaction and cleanliness of pipeline steel

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 Iron and Steel Research International 2024年第4期31卷 849-860页

作者： Guang-mei Yang Cheng Yuan Chang Liu qiang Wang Guang-qiang Li Yong-shun Zou Ao Huang The State Key Laboratory of Refractories and Metallurgy Wuhan University of Science and TechnologyWuhan 430081HubeiChina Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education Wuhan University of Science and TechnologyWuhan 430081HubeiChina

The interaction of MgO-MgAl_(2.O_(4)-based and MgO-Cr_(2.O_(3)-based refractories with X70 molten steel was studied by immersion experiments at 1560℃.The effects of immersion time(30 and 60 min)on the contents of total oxygen(TO),Al,Nb,Si,Mn,and Cr as well as the composition,number density,and size distribution of inclusions in the molten steel were *** influence of the penetration and erosion degree of the molten steel to the refractory on the steel-refractory interface layer was *** results show that,at 1560℃,the MgO-MgAl_(2.O_(4)-based refractory can better control the contents of TO and the composition of molten steel compared with the MgO-Cr_(2.O_(3)-based *** TO content is only 16×10^(-4) wt.%in the molten steel after reacted with the Mg0-MgAl_(2.O_(4)-based refractory at the end point of refining,4 accounting for 11.5%of that reacted with the MgO-Cr_(2.O_(3)-based refractory(139×10^(-4) wt.%).The number density of inclusions is only 14 mm^(-2.,and the average size ofinclusions is only 1.31μm,with thelargest proportion of inclusions in 1-2.m(70%).The Al_(2.O_(3)-MnS-CaO complex inclusions in the original steel changed to complex inclusions dominated by Cr-Nb-Mn-S-O and ***_(2.O_(3),corresponding to the MgO-Cr_(2.O_(3)-based and MgO-MgAl_(2.O_(4)-based refractories,*** ***_(2.O_(3) layer was formed at the reaction interface between MgO-MgAl_(2.O_(4)-based refractory and molten steel,which is helpful to restrict the erosion of refractories and the pollution of molten *** damage mechanism of the MgO-Cr_(2.O_(3)-based refractory is mainly permeation and chemical reaction,while the damage of the MgO-MgAl_(2.O_(4)-based refractory is mainlyscouring erosion.

关键词： MgO-Cr_(2.O_(3)-based refractory MgO-MgAl O_(4)-based refractory Nonmetallic inclusion Erosion interface layer Steel penetration

Approximate contact solutions for non-axisymmetric homogeneous and power-law graded elastic bodies:A practical tool for design engineers and tribologists

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Friction 2024年第2期12卷 340-355页

作者： Valentin L.POPOV qiang LI Emanuel WILLERT Institute of Mechanics Technische Universität BerlinBerlin 10623Germany

In two recent papers,approximate solutions for compact non-axisymmetric contact problems of homogeneous and power-law graded elastic bodies have been suggested,which provide explicit analytical relations for the force–approach relation,the size and the shape of the contact area,as well as for the pressure distribution *** solutions were derived for profiles,which only slightly deviate from the axisymmetric *** the present paper,they undergo an extensive testing and validation by comparison of solutions with a great variety of profile shapes with numerical solutions obtained by the fast Fourier transform(FFT)-assisted boundary element method(BEM).Examples are given with quite significant deviations from axial symmetry and show surprisingly good agreement with numerical solutions.

关键词： normal contact non-axisymmetric indenter extremal principle generalized method of dimensionality reduction(MDR) functional elastic grading

One more step to realistic CO_(2. reduction reactions——geometric structures evolutions at gas-solid interface

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Rare Metals 2024年第2期43卷 849-852页

作者： Ya-qiang Xie Xin Yu Ting Wang College of the Environment and Ecology Xiamen UniversityXiamen361102China

A rational design of copper(Cu)nanocatalyst is critical to the efficient carbon dioxide(CO_(2.)conversion toward C1/C2.chemical ***,the lack of actual information on the vicinal Cu interfaces hinders the intrinsic activitystructure correlation *** with atomic-scale in situ characterizations(AP-STM and synchrotron-based AP-XPS),Park and co-workers study and identify the adsorbate-driven morphological evolution of Cu nanoclusters on the Cu(997)surface,providing real-space evidence for the critical role of vicinal structures on Cu *** observed surface roughening trends caused by dissociated atomic oxygen and CO adsorbates subsequently affect the result of successive catalytic reactions to produce critical intermediates,such as carbonate and formate,during the CO_(2.reduction reaction.

关键词： reaction critical rational

维普期刊数据库

Micromechanics of Thermal Conductive Composites:Review,Developments and Applications

在线全文

学校读者我要写书评

暂无评论

Acta Mechanica Solida Sinica 2024年第2期37卷 215-237页

作者： Guannan Wang Yulin Huang Mengyuan Gao qiang Chen Department of Civil Engineering Zhejiang UniversityHangzhou310058China Center for Balance Architecture Zhejiang UniversityHangzhou310007China School of Mechanical Engineering Xi’an Jiaotong UniversityXi’an710049China

Micromechanics investigations of composites with fiber-shaped reinforcement are extensively applied in the engineering design and theoretical analysis of thermal composites in the aerospace engineering and high-tech *** this paper,a critical review of various classical micromechanics approaches is provided based on the classification framework and the development of micromechanics *** numerical micromechanics tools have been developed to overcome limitations through exactly/approximately solving the internal governing equations of *** connections and limitations of those models are also investigated and discussed,based on which three recently developed numerical or semi-analytical models are explained,including finite-element micromechanics,finite-volume direct averaging micromechanics,and locally exact homogenization theory,as well as machine learning *** it is almost inevitable to mention the interfacial effects on thermal behavior of fibrous composites,we review the new mathematical relations that interrupt the original continuity conditions due to the existence of interphase/interface within unit *** speaking,the interphase/interface is demonstrated to play a significant role in influencing the effective coefficients and localized thermal *** present work also briefly reviews the application of micromechanics tools in emerging engineered woven composites,natural fibrous composites,and ablative thermal protection *** is demonstrated that sophisticated micromechanics tools are always demanded for investigating the effective and localized responses of thermal fibrous composites.

关键词： Micromechanics models Thermal fibrous composites Microstructural detail-free models Semi-analytical and numerical methods Interfacial effects Woven composites Natural composites

Finite-Time Stabilization for Constrained Discrete-time Systems by Using Model Predictive Control

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

IEEE/CAA Journal of Automatica Sinica 2024年第7期11卷 1656-1666页

作者： Bing Zhu Xiaozhuoer Yuan Li Dai Zhiwen qiang IEEE the Seventh Research Division Beihang UniversityBeijing 100191China the School of Automation Beijing Institute of TechnologyBeijing 100081China

In this paper, a model predictive control(MPC)framework is proposed for finite-time stabilization of linear and nonlinear discrete-time systems subject to state and control constraints. The proposed MPC framework guarantees the finite-time convergence property by assigning the control horizon equal to the dimension of the overall system, and only penalizing the terminal cost in the optimization, where the stage costs are not penalized explicitly. A terminal inequality constraint is added to guarantee the feasibility and stability of the closed-loop *** feasibility can be improved via augmentation. The finite-time convergence of the proposed MPC is proved theoretically,and is supported by simulation examples.

关键词： Constraints deadbeat control finite-time stabilization model predictive control(MPC)

维普期刊数据库

The Sequential Pricing of Ride-Hailing System with Rental Service in the Context of Fleet Electrification

在线全文

学校读者我要写书评

暂无评论

Journal of Systems Science and Systems Engineering 2024年第1期33卷 77-105页

作者： Yaoyao Ku Peng Wu qiang Ren Yiqing Wang Business School Sichuan UniversityChengdu610065China

Surging demand and reduced capacity in the ride-hailing industry have prompted numerous ride-hailing platforms to build their own car-rental services catering to drivers who do not possess private vehicles. However, the trade-off between the ride-hailing service and the car-rental service is an important issue that is still unclear in theory. Moreover, ride-hailing platforms are transitioning towards all-electric fleets in the context of Carbon Neutrality goals and government regulations. This paper considers a ride-hailing system comprising a monopolist ride-hailing platform, an electric vehicle (EV) rental firm, and a gasoline vehicle (GV) rental firm. Furthermore, we build a stylized model to study the sequential pricing of the system. The equilibrium outcomes show the significant impact of the ride-hailing platform’s decision to continue or withdraw offering EV rental services on EV and GV drivers’ net earnings, rental prices, and wages. The ride-hailing platform providing EV rental services increases EV drivers’ net earnings but decreases the GV driver wages and rental prices. However, the EV rental service offered by the ride-hailing platform does not necessarily lead to an increased total profit for the system. The improved profitability of the system by the ride-hailing platform providing EV rental services is contingent upon lower rider prices and higher fuel costs. The ride-hailing platform’s EV rental services provision also effectively fosters the ride-hailing fleet’s electrification. Furthermore, as the number of riders increases, the ride-hailing platform should reduce the commission rate for EV drivers to maintain competitiveness and profitability.

关键词： Ride-hailing system car rental fleet electrification sequential pricing differential wage scheme