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Application of Nd:YAG Laser Welding to Implantable Neuro-Stimulator

Chinese Journal of Mechanical Engineering 2011年第6期24卷 1103-1110页

作者： ZHOU Zhenggan ni Xiansheng WEN Xiongwei LI Luming Institute for Nondestructive Testing and Mechatronics Engineering Beihang University Beijing 100191 China Tsinghua Space Center Tsinghua University Beijing 100084 China

It is difficult to weld the material and structure of implantable neuro-stimulator such as pure medical titanium and irregular outside shield by conventional arc welding *** there are few reports on the neuro stimulator sealing technology,and none of them have simultaneously consid.r.d the quality control *** ord.r.to develop the sealing proced.r. and quality control methods,an investigation of applying Nd：YAG laser welding to implantable neuro-stimulator components is carried ***,the automatic Nd：YAG laser welding system equipped with proper fixture configuration is introduced.A special fixture structure is illustrated and the key point for the device is to reduce the fit-up gap between the two ***,a novel welding process technique is proposed to satisfy the engineering *** optimized process parameters for titanium shell,feedthrough and fastener are provided and concluded by an orthogonal ***,different quality control measures such as visual inspection,X-ray detecting and leakage testing,are presented on the final *** results show that the Nd：YAG laser welding applied on the implanted neuro-stimulator und.r.optimized parameters can prevent welding defects and improve the weld joints *** of various quality control methods will guarantee the sealing performance and mechanical properties of the *** is confirmed that the processing proced.r. and quality methods can not only resolve the process technology on welding ultra-thin structure of medical device,but also provide the reference for other implantable device.

关键词： laser beam welding titanium process technique quality control nondestructive testing (NdT)

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Accuracy Analysis and design of A3 Parallel Spindle Head

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Chinese Journal of Mechanical Engineering 2016年第2期29卷 239-249页

作者： ni Yanbing ZHANG Biao SUN Yupeng ZHANG Yuan School of Mechanical Engineering Tianjin University Tianjin 300072 China China Faw Group Corporation r&d Center Changchun 130000 China

As functional components of machine tools, parallel mechanisms are widely used in high efficiency machining of aviation components, and accuracy is one of the critical technical indexes. Lots of researchers have focused on the accuracy problem of parallel mechanisms, but in terms of controlling the errors and improving the accuracy in the stage of design and manufacturing, further efforts are required. Aiming at the accuracy design of a 3-dOF parallel spindle head（A3 head）, its error model, sensitivity analysis and tolerance allocation are investigated. Based on the inverse kinematic analysis, the error model of A3 head is established by using the first-ord.r.perturbation theory and vector chain method. According to the mapping property of motion and constraint Jacobian matrix, the compensatable and uncompensatable error sources which affect the accuracy in the end-effector are separated. Furthermore, sensitivity analysis is performed on the uncompensatable error sources. The sensitivity probabilistic model is established and the global sensitivity index is proposed to analyze the influence of the uncompensatable error sources on the accuracy in the end-effector of the mechanism. The results show that orientation error sources have bigger effect on the accuracy in the end-effector. Based upon the sensitivity analysis results, the tolerance design is converted into the issue of nonlinearly constrained optimization with the manufacturing cost minimum being the optimization objective. By utilizing the genetic algorithm, the allocation of the tolerances on each component is finally determined. According to the tolerance allocation results, the tolerance ranges of ten kinds of geometric error sources are obtained. These research achievements can provide fundamental guidelines for component manufacturing and assembly of this kind of parallel mechanisms.

关键词： A3 head error model sensitivity analysis tolerance allocation

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Non-random vibration analysis for general viscous damping systems

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Chinese Journal of Aeronautics 2019年第12期32卷 2655-2666页

作者： Chao JIANG Long LIU Jinwu LI Bingyu ni State Key Laboratory of Advanced design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University

The authors recently developed a kind of non-probabilistic analysis method, named as‘non-random vibration analysis’, to deal with the important random vibration problems, in which the excitation and.r.sponse are both given in the form of interval process rather than stochastic process. Since it has some attractive advantages such as easy to und.r.tand, convenient to use and small dependence on samples, the non-random vibration analysis method is expected to be an effective supplement of the traditional random vibration theory. In this paper, we further extend the nonrandom vibration analysis into the general viscous damping system, and formulate a method to calculate the dynamic response bounds of a viscous damping vibration system und.r.uncertain excitations. Firstly, the unit impulse response matrix of the system is obtained by using a complex mode superposition method. Secondly, an analytic formulation of the system dynamic response middle point and.r.dius und.r.uncertain excitations is d.r.ved based on the duhamel’s integral, and thus the upper and lower response bounds of the system can be obtained. Finally, two numerical examples are investigated to demonstrate the effectiveness of the proposed method.

关键词： Complex mode dynamic response bounds Interval process random vibration Viscous damping system

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Evolution mechanisms of microstructure and mechanical properties in a friction stir welded ultrahigh-strength quenching and partitioning steel

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Journal of Materials Science & Technology 2022年第7期102卷 213-223页

作者： Z.W.Wang J.F.Zhang G.M.Xie L.H.Wu H.Zhang P.Xue d.r.ni B.L.Xiao Z.Y.Ma Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China State Key Laboratory of rolling and Automation Northeastern UniversityShenyang110819China

Ultrahigh-strength quenching and partitioning(Q&P) steels have attracted strong interests in the auto manufactory,while the comprehensive und.r.tanding in the microstructure and mechanical behavior of their welded joints is highly needed to enrich their *** the present work,it is designed to make an insight into these imperative *** strength Q&P 1180 steel joints to parent metal were successfully fabricated via friction stir welding(FSW) technique und.r.different parameters. Apparent hardening and softening were observed in stir zone(SZ) and heat-affected zone(HAZ) respectively,whose microstructures strongly depended on the peak temperature and cooling rate d.r.ng *** formation of fresh martensite was the main mechanism for the SZ hardening,while the decomposition of metastable phases played key roles in the microhardness drop of the HAZ.A heat source zone-isothermal phase transition layer model was proposed to clarify the impregnability of the joint strength und.r.parameter *** dual-phase structure,nano-carbide particles,tempered initial martensite,and ultrafine-grained ferrite synergistically improved the strain hardening ability of the HAZ,which eventually resulted in the equal strength FSW joints.

关键词： Ultrahigh-strength Q&P steel Friction stir welding Microstructure Mechanical property Strain hardening

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Effects of Nano-Y_2O_3 and Sintering Parameters on the Fabrication of PM duplex and Ferritic Stainless Steels

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Acta Metallurgica Sinica(English Letters) 2016年第1期29卷 58-71页

作者： r.Shashanka d.Chaira department of Metallurgical and Materials Engineering National Institute of Technology

Here we report the effects of nano-Y203 addition, sintering atmosphere and time d.r.ng on the fabrication of PM duplex and ferritic stainless steels composites by dual-drive planetary milling of elemental Fe, Cr and ni powd.r. followed by conventional pressureless sintering. Yttria-free and yttria-dispersed duplex and ferritic stainless steels are fabricated by conventional sintering at 1000, 1200 and 1400 ℃ temperatures und.r.argon atmosphere. In another set of experiment, yttria-free and yttria-dispersed duplex and ferritic stainless steels are consolidated at 1000 ℃ for l h und.r.nitrogen atmosphere to study the effect of sintering atmosphere. It has been found that densities of duplex and yttria- dispersed duplex stainless steel increase from 71% to 91% and 78% to 94%, respectively, with the increase in sintering temperature. Similarly, hardness value increases from 257 to 567 HV25 in case of duplex, and from 332 to 576 HV25 in yttria-dispersed duplex stainless steel. X-ray diffraction analysis shows the domination of more intense austenite phase than ferrite at higher sintering temperature and also in nitrogen atmosphere. It is also evident that addition of yttria enhances phase transformation from a-Fe to 7-Fe. duplex and yttria-dispersed duplex stainless steels exhibit the maximum com- pressive yield strength of 360 and 312 MPa, respectively.

关键词： Nano-Y2O3 Composites Stainless steel Powd.r.metallurgy (PM) Mechanical properties Microstructure Phase transitions

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rupture d.r.ctivity of the August 3rd, 2014 Ludian earthquake(Yunan, China)

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Science China Earth Sciences 2015年第3期58卷 795-804页

作者： HE XiaoHui ni Sidao LIU Jie Mengcheng National Geophysical Observatory University of Science and Technology of China State Key Laboratory of Geodesy and Earth's dynamics Institute of Geodesy and Geophysics China Earthquake Networks Center

An M6.5 earthquake occurred on August 3rd, 2014 in Ludian of Yunnan Province in China, causing severe casualty and economic loss. Local broadband waveform inversion with the CAP method demonstrates that the earthquake is a strike-slip event, with the strike along 70° and 160° for the two nodal planes respectively. However, the geological structure in the epicentral region is complicated with abundant active faults, and it is challenging to identify the seismogenic fault with the focal plane solutions due to nodal-plane ambiguity. We resolved the rupture d.r.ctivity by measuring the difference between centroid location and hypocenter of the Ludian earthquake with the time shift from CAP inversion, and found that the nodal plane with the strike of 160° is the ruptured fault plane. Moreover, the rupture is found to propagate from northwest to southeast.

关键词： rupture d.r.ctivity focal mechanism Ludian earthquake strong ground motion

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Influence of Co Content on raman and Photoluminescence Spectra of Co doped ZnO Nanowires

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Journal of Materials Science & Technology 2012年第4期28卷 313-316页

作者： Y.Q. Chang P.W. Wang S.L. ni Y. Long X.d. Li School of Materials Science anti Engineering University of Science and Technology Beijing Beijing 100083 China department of Physics National Key Laboratory of Mesoscopic Physics Peking University Beijing 100871 China

Co doped ZnO nanowires with different Co contents have been fabricated by a chemical vapor deposition method. X-ray diffraction results show that all the samples are of single phase and crystallize in wurtzite ZnO structure. The lattice parameter a increases with increasing Co content, while the parameter c has no obvious change with increasing Co. raman spectra show that the nonpolar E2（High） mode becomes broad and weak with the doping of Co, which indicates that the incorporation of Co causes structural disord.r.in the crystalline columnar ZnO lattice. The photolurninescence spectra exhibit that the position of the ultraviolet emission shifts to short wavelength and the intensity decreases with increasing Co. The green emission is affected by two contrary factors. It is increased by the introduced defects, but suppressed by the interaction between Co doping and native defects and the later affects it more significantly.

关键词： Co doped ZnO nanowires raman Photoluminescence Single phase

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The hydrogen and oxygen isotopic compositions of hydroxyl in clay mineral from a weathering profile： New proxies for paleo-climate change？

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Acta Geochimica 2017年第3期36卷 370-373页

作者： Chengfan Yang Shouye Yang ni Su State Key Laboratory of Marine Geology Tongji University 1239 Siping Road Shanghai 200092 People's Republic of China

recent studies suggest that the hydrogen and oxygen isotopic compositions of clay minerals can indicate ***,we report mineralogy and stable isotopic records(d d and δ^(18)O_(OH))of a weathering profile located in the Fujian Province,aiming to validate whether hydroxyl stable isotopes can indicate paleo-precipitation and *** results indicate that the d d and δ^(18)O_(OH)changes in the kaolinite hydroxyl of the weathering profile are basically determined by the isotopic composition of paleo-meteoric water and paleotemperature,***,whether the d d and δ^(18)O_(OH)of kaolinite can quantitatively indicate paleo-precipitation and paleo-temperature needs to be verified further,and especially,the structural oxygen isotopic composition that is the essential element for the kaolinite formation temperature calculation has to be constrained in future work.

关键词： Weathering profile Hydrogen and oxygen isotopes Hydroxyl Kaolinite

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dielectric and infrared properties of SrTiO_3 single crystal doped by 3d (V,Mn,Fe,ni) and 4f (Nd,Sm,Er) ions

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Chinese Physics B 2014年第2期23卷 369-374页

作者： S.Maletic d.Maletic I.Petronijevic J.dojcilovic d.M.Popovic Faculty of Physics University of Belgrade Institute of Physics University of Belgrade

In this study, the effects of doping by 3d （V, Mn, Fe, ni） and 4f （Nd, Sm, Er） ions on dielectric and infrared properties of SrTiO3 （STO） single crystals are investigated. It is well known that doping of the SrTiO3 can change the dielectric properties of the STO from an insulator to an n-type semiconductor, and even to a metallic conductor. dielectric and infrared （Ir） properties of the undoped STO and doped STO single crystals are analyzed using dielectric spectroscopy （80 kHz-5 MHz）, transmission （200 cm^-1-4000 cm^-1）, and.r.flection spectroscopy （50 cm^-1-2000 cm^-1）. It is found that doping by the 3d ions reduces the value of dielectric permittivity, but the trend of temperature dependence of the dielectric permittivity remains almost unchanged. On the other hand, dielectric spectroscopy measurements for samples doped by 4f ions show the anomalous behaviors of the dielectric permittivity at temperatures around the temperature of the structural phase transition. There are two fractures of temperature dependences of inverse dielectric permittivity εr^-1 （T）. Transmittance spectroscopy measurements show that there are differences in the shape of the spectrum in the mid-Ir region between the undoped STO and the one doped by 4f ions. The differences in the reflectance spectrum between the STO：Nd and STO are analyzed in detail.

关键词： doping dielectric properties phase transitions infrared spectroscopy

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Coupled modeling of rainfall-induced floods and sediment transport at the catchment scale

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International Journal of Sediment research 2022年第6期37卷 715-728页

作者： ronglan Huang Yufang ni Zhixian Cao State Key Laboratory of Water resources and Hydropower Engineering Science Wuhan University

rainfall-induced floods may trigger intense sediment transport on erodible catchments, especially on the Loess Plateau in China, which in turn modifies the floods. However, the role of sediment transport in modifying floods has to date remained poorly und.r.tood. Concurrently, traditional hydrodynamic models for rainfall-induced floods typically ignore sediment transport, which may lead to inaccurate results for highly erodible catchments. Here, a two-dimensional(2 d) coupled shallow water hydro-sedimentmorphodynamic(SHSM) model, based on the Finite Volume Method on unstructured meshes and parallel computing, is proposed and applied to simulate rainfall-induced floods in the Zhidan catchment on the Loess Plateau, Shaanxi Province, China. For six historical floods of return periods up to 2 years, the numerical results compare well with observations of discharge hydrographs at the catchment outlet. The computed.r.noff-sediment yield.r.lation is quantitatively reasonable as compared with other catchments und.r.similar geographical conditions. It is revealed that neglecting sediment transport leads to und.r.stimation of peak discharge of the flood by 14%-45%, whilst its effect on the timing of the peak discharge varies for different flood events. For 18 design floods with return periods of 10-500 years, sediment transport may lead to higher peak discharge by around 9%-15%. The temporal pattern of concentrated.r.infall in a short period may lead to a larger exponent value of the power function for the runoff-sediment yield.r.lation. The current finding leads us to propose that incorporating sediment transport in rainfallinduced flood modeling is warranted. The SHSM model is applicable to flood and sediment modeling at the catchment scale in support of risk management and water and soil management.

关键词： Catchment Floods Hydro-sediment-morphodynamic modeling Sediment transport Soil erosion

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