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Experimental and finite element analysis on determining the fatigue life of pb-free solder joint(sn-0.5Cu-3Bi-1Ag)used in electronic packages under harmonic loads

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International Journal of Modeling, simulation, and scientific Computing 2020年第3期11卷 60-67页

作者： Jayesh s jacob Elias Department of Mechanical Engineering school of Engineering Cochin University of Science and Technology KochiKerala-682022India

Electronic packages that are used these days are exposed to different types of vibration loadings in their usage *** vibration exposure can be categorized as harmonic and random *** reliability assessment of modern electronic systems is considered,vibration loading has an important role to *** of the biggest challenges facing today is the accurate and rapid assessment of fatigue life under the vibration *** solder joints were made of lead-tin *** to many environment legislations and rules,lead is prohibited as an ingredient in the solder *** reason for the prohibition of the usage of the lead is that it poisons the *** this study,sn-0.5Cu-3Bi-1Ag is used as the lead-free solder *** life prediction of electronic package containing sAC405 is conducted with the aid of vibration testing and Finite element analysis under harmonic vibration loading.A specially designed Plastic Ball Grid Array Package(PBGA)component is mounted on Printed Circuit Board(PCB).It is taken as a test vehicle for the vibration *** test vehicle is excited by a sinusoidal *** frequency of this excitation equals the fundamental frequency of the test vehicle and it is continued till the component *** the solder balls are very small for direct measurement,Finite Element analysis(FEA)is used for noting down the *** stress versus failures cycles(s-N)curve is made by relating both the stresses on the solder balls obtained and the number of failure cycles from vibration *** fatigue life of the component can be estimated from the generated s-N *** is analyzed that the methodology is effective in predicting the component’s ***,the reliability of electronic package can be improved.

关键词： PCB lead free solder joint FEA PBGA s-N curve

Management of symptomatic ureteric stumps laparoscopically

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Asian Journal of Andrology 2001年第2期3卷 147-150页

作者： A.M.Khan s.jacob Department of surgery King George Hospital Ilford Essex IG1 2HL UKDepartment of Surgery King George Hospital Ilford Essex IG1 2HL UK

Aim: To study the advantage of excision of the distal symptomatic ureteric stumps with the retroperitoneal laparo-scopic approach. Methods: Four patients who had failed to settle their symptoms with the initial conservative man-agement were included in the study. All underwent excision of the distal symptomatic ureteric stumps with the retroperi-toneal laparoscopic approach and then received prophylactic antibiotics. Results: We have achieved better resultsthan those reported in the literature in terms of operating time (mean 1 h 45 min), blood loss ( stopera-tive recovery (within 12 h) and hospital stay ( sion; Retroperitoneal laparoscopic excision is asafe, simple and effective method in the management of symptomatic ureteric stumps.

关键词： ureter laparoscopy retroperitoneal space

Water yield and biomass production for on a eucalypt-dominated Mediterranean catchment under different climate scenarios

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Journal of Forestry Research 2023年第5期34卷 1263-1278页

作者： Joao Rocha Ana Quintela Dalila serpa Jan jacob Keizer sérgio Fabres RAIZ-Forest and Paper Research Institute Quinta de S.FranciscoRua JoséEstevao(EN 230-1)3800–783 EixoAveiroPortugal Department of Environment and Planning Centre of Environmental and Marine Studies(CESAM)University of AveiroCampus Universitário de Santiago3810–193 AveiroPortugal

Worldwide,forests are vital in the regulation of the water cycle regulation and in water balance *** of ecohydrological responses of production forests is essential to support management strategies,especially where water is already *** climatological patterns are expected to impact thermopluviometric regimes,water cycle components,hydrological responses,and plant physiology,evapotranspiration rates,crop productivity and land management *** work(1)assessed the impacts of different predicted climate conditions on water yield;(2)inferred the impacts of climate change on biomass production on eucalypt-to-eucalypt succes *** this end,the widely accepted soil and Water Assessment Tool(sWAT)was run with the RCA,HIRHAM5 and RACMO climate models for two emission scenarios(RCP 4.5 and8.5).Three 12-year periods were considered to simulate tree growth under coppice *** results revealed an overall reduction in streamflow and water yield in the catchment in line with the projected reduction in total annual ***,HIRHAM5 and RACMO models forecast a slight shift in seasonal streamflow of up to 2 months(for2024-2048)in line with the projected increase in precipitation from May to *** biomass production,the extreme climate model(RCA)and severe emis sion scenario(RCP 8.5)predicted a decrease up to 46%.However,in the less extreme and more-correlated(with actual catchment climate conditions)climate models(RACMO and HIRHAM5)and in the less extreme emission scenario(RCP 4.5),biomass production increased(up to 20%),and the growth cycle was slightly *** was proven to be a valuable tool to assess climate change impacts on a eucalypt-dominated catchment and is a suitable decision-support tool for forest managers.

关键词： Climate scenarios Forested catchments Forest ecohydrological modelling Eucalypt biomass production sWAT model

sulfurized-polyacrylonitrile in lithium-sulfur batteries:Interactions between undercoordinated carbons and polymer structure under low lithiation

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Journal of Energy Chemistry 2022年第3期31卷 587-596,I0016页

作者： samuel Bertolini Timo jacob Institute of Electrochemistry Ulm UniversityAlbert-Einstein-Allee 4789081 UlmGermany Helmholtz-Institute Ulm(HIU) Electrochemical Energy StorageHelmholtzstr.1189081 UlmGermany Karlsruhe Institute of Technology(KIT) P.O.Box 364076021 KarlsruheGermany

Lithium-sulfur battery(LsB)represents an important candidate to be used in energy storage applications,due to its high specific ***-polyacrylonitrile(sPAN)is a candidate as a host material in LsB to replace graphite,due to its ability to chemisorb polysulfides(Pss).The sulfur chains attached to the polymer can reversibly form Li2s,and sPAN indicates to have a good cyclability and better performance than graphite,thus,sPAN acts partially as an active and also as a host *** this study,we investigated the capacity of the solvent or the sPAN to lose a hydrogen atom from the backbone,to predict possible anodic reactions between solvent and host *** simulation suggests that the photophilic salts may preferentially react with the solvent,and possibly building a cathode electrolyte interphase(CEI).We observed that an undercoordinated carbon(C_(uc))can be thermodynamically created,due to *** Cuccan react with the solvent on the polymer backbone through different mechanisms,however,the simulations indicated that the reaction should be affected by the interaction between the solvent and C_(uc),according to sPAN’s ***,C_(uc)reacts with long sulfur chains attached to sPAN,capturing sulfur and forming a C-s bond.A sulfur chain from one sPAN can connect to another polymer backbone,however,this process is affected by lithiation and ***,this work also investigates the formation of interconnected sPAN structures and the multiple C_(uc)effects.

关键词： Density functional theory Ab initio molecular dynamics Lithium-sulfur batteries sulfurized-polyacrylonitrile

The Mathematical Theory of Multifocal Lenses(Dedicated to Professor Haim Brezis on the occasion of his 70th birthday)

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Chinese Annals of Mathematics,series B 2017年第2期38卷 647-660页

作者： jacob RUBINsTEIN department of mathematics TechnionHaifa 32000Israel

This paper presents the fundamental optical concepts of designing multifocal ophthalmic lenses and the mathematical methods associated with them. In particular, it is shown that the design methodology is heavily based on differential geometric ideas such as Willmore surfaces. A key role is played by Hamilton's eikonal functions. It is shown that these functions capture all the information on the local blur and distortion created by the lenses. Along the way, formulas for computing the eikonal functions are derived. Finally,the author lists a few intriguing mathematical problems and novel concepts in optics as future projects.

关键词： Optical design, Differential geometry, Eikonal functions,Multifocal lenses

Mixed mode properties of CNT reinforced composites using Arcan test rig

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Frontiers of structural and Civil Engineering 2015年第4期9卷 397-404页

作者： jacob MUTHU DsT-NRF Centre of Excellence in strong Materials and RP/Composite Facility School of Mechanical Industrial and AeronauticalEngineering University of the Witwatersrand Johannesburg South Africa

Composite materials reinforced with carbon nanotubes were mechanical tested using Arcan test rig under Mode-I, Mode-II and mixed mode loading conditions to obtain their fracture properties. The butterfly composite specimens were fabricated with 0.02, 0.05 and 0.1 wt % CNTs. The polyester/CNT composite was fabricated using VRTM (Vacuum Resin Transfer Molding) where the CNTs were first functionalised to reach an optimum properties. Arcan test rig was designed and fabricated to work with the shimadzu testing machine. The results show that the functionalised CNTs have improved the fracture behavior by acting as bridge between the cracked face. In addition, the fracture properties were not improved for the higher weight fraction of 0.1 wt% CNTs.

关键词： CNT composites Arcan test rig stress intensity factor

Hydration lubrication

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Friction 2013年第1期1卷 1-23页

作者： jacob KLEIN Department of Materials&Interfaces Weizmann Institute of ScienceRehovot76100Israel

The hydration lubrication paradigm,whereby hydration layers are both strongly held by the charges they surround,and so can support large pressures without being squeezed out,and at the same time remain very rapidly relaxing and so have a fluid response to shear,provides a framework for understanding,controlling,and designing very efficient boundary lubrication systems in aqueous and biological *** review discusses the properties of confined water,which-unlike organic solvents-retains its fluidity down to molecularly thin *** then describes lubrication by hydrated ions trapped between charged surfaces,and by other hydrated boundary species including charged and zwitterionic polymer brushes,surfactant monolayers,liposomes,and biological macromolecules implicated in synovial joint ***,challenges and prospects for future development of this new boundary lubrication approach are considered.

关键词： hydration lubrication biolubrication boundary lubrication liposomes polymer brushes hydration repulsion hydration layers

Properties of the secondary Hochschild Homology

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Algebra Colloquium 2018年第2期25卷 225-242页

作者： jacob Laubacher Department of Mathematics St. Norbert College De Pere Wisconsin 54115 USA

In this paper we study properties of the secondary Hochschild homology of the triple （A, B, ε） with coefficients in M. We establish a type of Morita equivalence between two triples and show that H.（（A,B,ε）; M） is invariant under this equivalence. We also prove the existence of an exact sequence which connects the usual and the secondary Hochschild homologies in low dimension~ allowing one to perform easy computations. The functoriality of H.（（A, B, ε）; M） is also discussed.

关键词： Hochschild homology Morita equivalence

symmetry breaking in thermal photonics

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Light(science & Applications) 2022年第12期11卷 2835-2836页

作者： Xueji Wang Zubin jacob Birck Nanotechnology Center Elmore Family School of Electrical and Computer EngineeringPurdue UniversityWest LafayetteIN 47907USA

Engineering symmetries in nanostructures and metasurfaces provides a new paradigm to control incoherent heat radiation for applications in energy conversion,thermal sources,infrared imaging,and radiative cooling.

关键词： thermal breaking radiative