可用于建筑结构检测的分布式光纤形变片

本文在光时域反射计 ( OTDR)和光纤形变片的基础上 ,提出了一种分布式光纤传感器 -分布式光纤形变片 .该检测方法属于 OTDR的损耗调制法 ,即通过测量粘贴于光纤形变片上的光纤弯曲损耗来获取测量点的应变量或位移量 .作者分别在微位移架和悬臂梁进行了位移检测和应变检测 ,结果表明该分布式光纤形变片提供了一种可检测应变量与位移量的检测方法 .值得注意的是 ,该分布式光纤形变片的传感网络采用时分复用的总线拓扑 。

聚焦离子束致形变微纳加工研究进展

聚焦离子束技术(focused ion beam,FIB)由于其高精度刻蚀、定点加工、实时成像等优势,常用于精密加工、TEM制样等领域。其工作机理通常为:刻蚀、淀积与成像。而基于FIB新的加工手段正在被探索和研究,其中就包括两种聚焦离子束致形变技术,分别为聚焦离子束应力引入致形变技术(FIB-stress induced deformation,FIBSID)和聚焦离子束物质再分布致形变技术(FIB-material-redistribution induced deformation,FIB-MRD)。前者通过控制FIB辐照时离子注入与溅射之间的竞争关系实现悬臂梁的多角度弯曲,后者利用粒子与物质作用时的瑞利不稳定性构建纳米结构,在一定意义上扩充了聚焦离子束的应用范围。运用上述方法可以加工三维微纳螺旋,悬浮光滑纳米弦以及大规模阵列化纳米网孔等多样化微/纳功能构件,在微流控系统,太赫兹通信,光学天线等领域具有很强的应用前景。

大面积场发射显示器支撑方案的计算机模拟

场发射显示器 (FED)的支撑结构用来抵抗器件外部大气压对阴阳极板造成的形变影响。预先确定和优化支撑系统方案 ,对于降低大面积FED器件制造成本是十分重要的。本文通过有限元分析方法 ,对 40英寸 ,长宽比 4∶3,采用墙式支撑条和 2mm厚阴阳板的FED器件的支撑方案进行了模拟计算。通过给出 170mm支撑墙在不同摆放位置情况下的极板应力以及形变分布 ,最后确定了二种可实际用于器件的支撑方案。

直通式热轧辊流道改进

锂电池极片的辊轧是锂电池极片生产过程中不可缺少的一环,极片作为锂电池的核心部件之一,其质量会直接影响到锂电池的性能。对直通式热轧辊进行仿真模拟,分析轧辊的温度-形变特性;通过模拟,确定轧辊流道的改进方向,并对改进后轧辊进行不同配油方案下的温度-形变特性分析。结果表明:结构改进可以提高轧辊表面温度均匀性,增加轧辊表面有效长度。

Dissolved Inorganic Arsenic in the Yellow Sea and the East China Sea—Distributions and Seasonal Variations

The distributions and seasonal variations of total dissolved inorganic arsenic （TDIAs, [TDIAs] = [As^5＋]＋[As^3＋]） and arsenite （As3.） in the Yellow Sea and East China Sea are presented hero based on the observations of 9 cruises carried out in 2000 - 2003. The study area covers a broad range of hydrographic and chemical properties. The emphasis is put on a southeast transect from Changjiang Estuary to the Ryukyu Islands （i.e. PN section） in the East China Sea to discuss the impact of terrestdal input on the marginal seas of China. Arsenic species （TDlAs and arsenite） are determined by selective hydride generation - atomic fluorescence spectrometry （HG-AFS）. TDIAs concentrations were high in the coastal area of Changjiang Estuary and decreased slightly towards the shelf region. High concentratiOns of TDIAs were also existed in the near bottom layer of shelf edge of the East China Sea which indicated another source of arsenic from the incursion of Kuroshio Waters. The seasonal variations of TDIAs in the study area depend on the hydrographic stages of Changjiang and the incursion intensity of Kuroshio Waters. Arsenite showed opposite distributions with TDIAs, with higher concentrations appeared at the surface layer of shelf region, which was positive correlated with the chlorophyll a. Biological conversion of arsenate into arsenite was hypothesized for the observed distribution pattern and its seasonal variations. The stoichoimetric ratios of As to P were estimated to be about 2×10^3 at PN Section in summer. The concentrations of dissolved arsenic in the Yellow Sea and East China Sea were comparable with other areas in the world.

新型铝包覆碳纤维导线力学性能分析研究

针对特高压输电线路中导线性能及输电能力的需求,以铝包覆结构的新型碳纤维导线为研究对象,建立新型导线与传统碳纤维导线的三维物理模型,采用有限元方法进行模拟计算,并分析比较了两种导线在抗拉性能、抗压性能等方面的力学特性。对比结果表明:在径向压力或轴向拉力作用下,相较于普通碳纤维导线存在的应力集中现象,新型导线的应力分布更为均匀,且在两种典型工况下的最大应力均小于传统导线;另一方面,两种碳纤维导线在不同工况下的形变分布基本一致。综合分析表明,新型铝包覆碳纤维复合芯导线能有效提升导线的抗压能力与抗拉能力,具有良好的力学性能。

Interspecific Transition Among Caragana microphylla, C. davazamcii and C. korshinskii Along Geographic Gradient. Ⅰ. Ecological and RAPD Evidence

The former plant population survey has shown that three genetically-related species, Caraganamicrophylla Lam., C. davazamcii Sancz. and C. korshinskii Kom., form a geographical replacement series inNei Mongol Plateau. The present study on population distribution, taxonomy, morphology, development andgenetic structure demonstrated that the geographical distribution of these three species was successiveand in gradual change, thus forming a geographical cline which extended from the east to the west of NeiMongol Plateau. With an analysis of climate change over time, it was considered that the formation of thisgeographical cline was a result of plant adaptation to its natural environment.

Adiabatic shear sensitivity of ductile metal based on gradient-dependent JOHNSON-COOK model

Based on the expression proposed by WANG for the local plastic shear deformation distribution in the adiabatic shear band（ASB） using gradient-dependent plasticity,the effects of 10 parameters on the adiabatic shear sensitivity were studied.The experimental data for a flow line in the ASB obtained by LIAO and DUFFY were fitted by use of the curve-fitting least squares method and the proposed expression.The critical plastic shear strains corresponding to the onset of the ASB for Ti-6Al-4V were assessed at different assigned ASB widths.It is found that the proposed expression describes well the non-linear deformation characteristics of the flow line in the ASB.Some parameters in the JOHNSON-COOK model are back-calculated using different critical plastic shear strains.The adiabatic shear sensitivity decreases as initial static yield stress,work to heat conversion factor and strain-rate parameter decrease,which is opposite to the effects of density,heat capacity,ambient temperature and strain-hardening exponent.The present model can predict the ASB width evolution process.The predicted ASB width decreases with straining until a stable value is reached.The famous model proposed by DODD and BAI only can predict a final stable value.

Effect of surface nanocrystallization and PPEC time on complex nanocrystalline hard layer fabricated by plasma electrolysis

Size distribution of nano-carbides produced by duplex treatments of surface nanocrystallization(by surface severe plastic deformation) and plasma electrolytic carburizing on CP-Ti was investigated.Skewness and kurtosis of Gussian shape distribution curves were studied and the effect of time was determined.The usage of longer time is more suitable for achieving less size of complex nano-carbides.Surface roughness of treated samples was measured.It is observed that there is an optimum level for time on surface roughness increasing(difference between two measured data).

Numerical Modeling of Neotectonic Movements and State of Stresses in the Central Seismic Gap Region,Garhwal Himalaya

This paper presents finite element modeling （FEM） to simulate the present-day stress field and crustal deformation using NE-SW structural section in the central Seismic Gap region of the Garhwal Himalaya. Our study deals with the effect of geometrical characteristics and rock layer parameters on the upper crust. Modeling results show that two types of tectonic regimes developed in the central Seismic Gap region： the geotectonics of the northern part has been controlled by regional compression, whereas southern part is characterized by regional extension. Correspondingly, thrust faults are induced in the northern part and normal faults are extensively developed in the southern front. Those evidences noticeably indicate that the compressive tectonic environment of the Himalaya becomes change into the extensional tectonic regime in its front. The computed shear stress accumulation along the northern fiat of Main Himalayan Thrust （MHT） implies that considerable amount of interseismic stress is building up along the MHT system in the Himalaya, which ultimately release through the possible future great Himalayan earthquake （M 〉 8）. The comparison between our modeled stress field, faulting pattern and horizontal shortening rate with the distribution of the microseismic events, focal mechanism solutions, active faulting and GPS data in the central Seismic Gap region shows good agreement.

VD-120t精炼炉真空罐盖结构分析及优化设计

真空罐盖是VD精炼炉的重要组成部分。利用Workbench完成VD-120 t精炼炉真空罐盖三维有限元结构分析;进行了真空罐盖不同加强筋结构的形变及应力分析、结构优化设计,并分析得到减小罐盖形变、应力的方法。

Longitudinal crack on slab surface at straightening stage during continuous casting using finite element method

Deformation behavior of slab at the straightening stage during continuous casting was simulated by the explicit dynamic finite element method,and the stress distribution along the width direction of the slab and its change regularity at slab center during continuous casting were obtained.The influence of distribution and change of stress on the propagation of longitudinal cracks on slab surface was discussed.The results show that the tensional stress appears on slab surface at the inner arc side and the compressive stress appears on slab surface at the outer arc side at stages 6-8 in straightening zone during continuous casting.Longitudinal cracks generally appear on slab top surface and do not appear on slab bottom surface,which are also observed in industry.

Tuning optical properties of ITO films grown by rf sputtering:Effects of oblique angle deposition and thermal annealing

Indium tin oxide(ITO)thin films were prepared using the technique of rf-sputtering with oblique angle deposition(OAD).The films were as-deposited and thermally treated at 250℃.The combination of substrate inclination and annealing was used for modifying morphological and structural properties that lead to changes of the optical properties.The resulting films show morphology of tilted nanocolumn,fissures among columns,and structural changes.The as-deposited films are structurally disordered with an amorphous component and the annealed films are crystallized and more ordered and the film diffractograms correspond to the cubic structure of In2O3.The refractive index could be modified up to 0.3 in as-deposited films and up to 0.15 in annealed films as functions of the inclination angle of the nanocolumns.Similarly,the band gap energy increases up to about 0.4 eV due to the reduction of the microstrain distribution.It is found that the microstrain distribution,which is related to lattice distortions,defects and the presence of fissures in the films,is the main feature that can be engineered through morphological modifications for achieving the adjustment of the optical properties.

Analysis of the dialectical relation between top coal caving and coal-gas outbtu rst

According to the different engineering mechanical states of top coal caving andnormal stoping of gaseous loose thick coal seams,the dialectical relation between thiscaving method and dynamic disasters was analyzed by simulating the change of stressstates in the process of top coal initial caving with different mining and caving ratios basedon the ANSYS10.0.The variation of elastic energy and methane expansion energy duringfirst top coal caving was analyzed by first weighting and periodic weighting and combiningwith coal stress and deformation distribution of top coal normal stoping as well as positiveand negative examples in top coal caving of outburst coal seam.The research shows thatthe outburst risk increases along with the increase of the caving ratio in the initial miningstage.In the period of normal stoping,when the mining and caving ratio is smaller than1:3 and hard and massive overlying strata do not exist (periodic weighting is not obvious),it is beneficial to control ground stress leading type outburst.Thus,it is unreasonable toprohibit top coal caving in dangerous and outburst prone areas.

Three dimensional finite element study on torsion extrusion processing of 1050 aluminum alloy

The capability of the torsion extrusion （TE） process as a severe plastic deformation （SPD） method was compared with the conventional forward extrusion （FE） process. The TE and FE processes were successfully performed on AA1050 alloy samples at room temperature. To simulate the above mentioned processes, finite element analysis was carried out using the commercial elasto-plastic finite element analysis ABAQUS/Explicit Simulation. It is shown that load requirement for the TE process is lower than that for the FE process. The equivalent plastic strain calculated by the FEA proved that higher values of strain are imposed to the sample in the TE process. The strain distribution for the TE sample at the final stage of extrusion shows smoother strain gradient in comparison with the one produced by the FE process.

Strain analysis of buried steel pipelines across strike-slip faults

Existing analytical methods of buried steel pipelines subjected to active strike-slip faults depended on a number of simplifications.To study the failure mechanism more accurately,a refined strain analytical methodology was proposed,taking the nonlinear characteristics of soil-pipeline interaction and pipe steel into account.Based on the elastic-beam and beam-on-elastic-foundation theories,the position of pipe potential destruction and the strain and deformation distributions along the pipeline were derived.Compared with existing analytical methods and three-dimensional nonlinear finite element analysis,the maximum axial total strains of pipe from the analytical methodology presented are in good agreement with the finite element results at small and intermediate fault movements and become gradually more conservative at large fault displacements.The position of pipe potential failure and the deformation distribution along the pipeline are fairly consistent with the finite element results.

Distribution of mineral species in different coal seams of Talcher coalfield and its transformation behavior at varying temperatures

Mineral phase characterization and thorough understanding of its transformation behavior during combustion are imperative to know the potential utilization of coal in the thermal industries. The primary objective of this work is to analyze the quality of Indian Coals and obtain their mineral species-specific information at different depths. The samples were obtained from Talcher Coalfield, Odisha, India. Coal from four seam sections in the Talcher coalfield, India are mainly high ash coal （〉50 %） and volatile matter deceases along with the seam depth. XRD results show that the major mineral phases present in the coal are quartz and kaolinite. Siderite, illite, and anatase were found in minor quantities. It has been observed that the clay minerals （kaolinite, silimanite, illite） decompose at higher temperature and traces of dolomite, mullite, hematite etc. are formed during the process of combustion. Among the four seams （M2, M12, M24 and M43） studied, ash of M43 has high A1203%, TIO2% and K20% content and low SIO2%, CaO% and MgO% content. High acid- to-base ratios contributed to high ash fusion temperatures （IDT 〉 1500 ℃） and low slagging potential of the coals studied. Relatively low fouling index （〈0.3） was estimated for all the coal seams studied. Furthermore, thermodynamic modeling software, FactSage, have been used to envision the mineral phase transformations that take place between 800 and 1500℃ during coal combustion.

Age, Growth and Distribution of the Antarctic Fish Chaenocephalus Aceratus Based on Otoliths

The Chaenocephalus aceratus were sampled in summers between 1979 and 1990. Their otoliths show pattern of daily microincrements as otoliths of similar species--Pseudochaenichthys georgianus and fishes both temperate and tropical waters. Changes of the microincrements growth pattern and otolith shape are described in relation to larval, hatching and metamorphosis stages have similar patterns for Ps. georgianus and Charnpsocephalus gunnari, reflecting similar habitats in their early life. Width of larvae-postlarvae daily increments are： （1.0-1.6）×10-3 SSI, （1.8-2.8）×10-3 SG1 and （1.5-2.4）×10-3 ANI. They were search and chosen automatically from density profiles of otolith tissues. Tissues were prepared by new saving time and materials way--one time up to 40 ones per microscopic glass. Age of fish estimated from microincrements was alike to that inferred from the body length distribution, otoliths mass （age （years） = 140.82 OM （g） ＋ 0.8546） and otolith shape changes--large in length and surface on medial plane. Those parameters create age groups of close neighbours. They have different environments. C. aceratus due to its adaptation to cold water, attain rapidly large body according to a growth equation： Lt= 75.1 ×10-3 （1-e-0.26（t-0.51）. Among large fishes there were only females.

Spatial acoustic emission evolution of red sandstone during multi-stage triaxial deformation

Multi-stage triaxial compression tests for cylindrical red sandstone specimens(diameter of 50 mm,height of 100 mm) were carried out with a rock mechanics testing system and spatial acoustic emission(AE) locations were obtained by adopting an AE monitoring system.Based on spatial AE distribution evolution of red sandstone during multi-stage triaxial deformation,the relation between spatial AE events and triaxial deformation of red sandstone was analyzed.The results show that before peak strength,the spatial AE events are not active and distribute stochastically in the specimen,while after peak strength,the spatial AE events are very active and focus on a local region beyond final microscopic failure plane.During multi-stage triaxial deformation with five different confining pressures,the spatial AE distribution evolution in the red sandstone was obtained.The obtained spatial AE locations of red sandstone at the final confining pressure agree very well with the ultimate failure experimental mode.Finally,the influence of confining pressure on the spatial AE evolution characteristics of red sandstone during triaxial deformation was discussed.The AE behavior of red sandstone during multi-stage triaxial deformation is interpreted in the light of the Kaiser effect,which has a significant meaning for predicting the unstable failure of engineering rock mass.

FE-based coupling simulation of Ti60 alloy in isothermal upsetting process

A constitutive equation was proposed to describe the effect of grain size on the deformation behavior.And a coupling simulation of deformation with heat transfer and microstructure was carried out in isothermal upsetting process of Ti60 alloy.The effects of processing parameters on the equivalent strain,the equivalent stress,the temperature rise and the grain size distribution in isothermal upsetting process of Ti60 alloy were analyzed.It is concluded that the uniformity of equivalent strain and equivalent stress increases with the increase of deformation temperature.However,the temperature rise and the grain size decreases with the increase of deformation temperature.The non-uniformity of equivalent strain,equivalent stress,temperature field and grain size increases with the increase of height reduction.And the calculated grain size using simulation is in good agreement with the experimental one.