扇面形散射元构建的二维光子晶体慢光模拟研究

本文用扇面形散射元构建空气孔型光子晶体模型,构建线缺陷波导,利用平面波展开法分别模拟其TM模式下的色散曲线,并通过改变散射元参数,求得群折射率、群速度、带宽、归一化延迟带宽积和色散常数,获得群折射率较大且带宽较大的理想模型。针对散射元,整体改变波导结构,分面对面型、背对背型和旋转30o三种,对其计算结果进行比较分析。

多元多形涤纶织物染整工艺探讨

通过对多元多形涤纶织物染整工艺的试验、研究,优化了工艺,提出了主要染整工艺的技术关键。

关于四元数形式小波的研究

建立了四元数形式单小波和多小波之间的对应关系 ,从而给出了由四元数单小波构造四元正交多小波的一种方法 ,并从矢量小波的角度 。

形意浑元桩

形意浑元桩据传是形意拳习练者为提高功力而必练的功法。陈规陋习所限,非入室弟子不传,公众场所不练,宁可失传、不可乱传,从而使此功法濒临绝迹。家师张董僧先生破除陈规,本着济世于人的原则,建国初期在中国医科大学组建体疗室,用此功法治疗慢性病。经五十多年实践证明,浑元桩功治病健身,深具科学原理,对久坐办公室人员、中老年人,亚健康的群体更为实用。为使全民健身运动更广泛地开展。特献此功法于读者。

土—基础共同作用分析的有限元/无限元耦合方法模型研究

为考虑土—基础共同作用,建立了有限元/无限元耦合方法分析模型。通过对同一结构体系分别应用有限元理论和有限元/无限元耦合方法比较,研究了有限元/无限元耦合体系中有限元范围在水平与竖向区域的不同取值对计算结果的影响,从而确定了有限元区域的计算范围。结果表明,有限元/无限元耦合方法对于研究共同作用问题具有较高的精度和显著的经济性。

Effect of wire diameter compression ratio on drawing deformation of micro copper wire

A crystal plasticity finite element model was developed for the drawing deformation of pure copper micro wire,based on rate-dependent crystal plasticity theory.The impact of wire diameter compression ratio on the micro-mechanical deformation behavior during the wire drawing process was investigated.Results indicate that the internal deformation and slip of the drawn wire are unevenly distributed,forming distinct slip and non-slip zones.Additionally,horizontal strain concentration bands develop within the drawn wire.As the wire diameter compression ratio increases,the strength of the slip systems and the extent of slip zones inside the deformation zone also increase.However,the fluctuating stress state,induced by contact pressure and frictional stress,results in a rough and uneven wire surface and diminishes the stability of the drawing process.

环形狭缝腔阵列光学特性的研究

设计了一种六角密排的二维环形纳米腔阵列结构,利用时域有限差分算法对该结构的光学特性进行了探究.仿真结果表明,在线性偏振光入射时,环形腔内可以形成多重圆柱形表面等离激元谐振,谐振波长的个数和大小与环形腔的结构参数相关.根据透、反射光谱,电场矢量的模式分布及截面电荷密度的分布,谐振波长处形成圆柱形表面等离激元,谐振波长处入射光能量大部分在环形腔内损耗,此时反射率为极小值,环形腔内的电场增强效应为极大值(光强增强可达1065倍).谐振波长与环形腔的结构参数(狭缝内径、狭缝外径、膜厚、环境介质折射率、金属的材质)相关,通过调节结构参数,谐振波长在350—2000 nm范围内可调.通过对比相同结构参数的单个环形腔和环形腔阵列的仿真结果,周期排布对环形腔内的圆柱形表面等离激元吸收峰位置影响不明显.该结构反射光谱对入射光电矢量偏振方向不敏感.谐振波长的可调控性对于表面拉曼增强和表面等离激元共振传感器的设计与优化具有指导性意义,且应用于折射率传感器时灵敏度可达1850 nm/RIU.

平面漏斗形微腔集成的高性能长波红外探测器

为实现量子阱红外光探测器件对垂直于阱结构的入射光吸收,减小模式体积,降低暗电流,提高比探测率D^(*),提高红外光探测器件性能,以10.55μm长波红外光为例,利用等离激元微腔与量子阱材料结合,形成F-P共振,增加GaAs/AlGaAs量子阱层的吸收率和器件的响应率。设计了平面漏斗形等离激元微腔集成的量子阱红外探测器(quantum well infrared photodetector,QWIP),使用基于有限元数值仿真方法对其进行分析。结果表明:平面漏斗形等离激元微腔集成的QWIP具有较小的光子模式体积和较高的局域场强,光吸收率维持在81%~89%的情况下,可以使探测材料体积减小38%~50%,获得的D^(*)比一般等离激元微腔集成的QWIP增大10%~15%。

In-situ Micro-CT analysis of deformation behavior in sandwich-structured meta-stable beta Ti−35Nb alloy

Beta Ti−35Nb sandwich-structured composites with various reinforcing layers were designed and produced using additive manufacturing(AM)to achieve a balance between light weight and high strength.The impact of reinforcing layers on the compressive deformation behavior of porous composites was investigated through micro-computed tomography(Micro-CT)and finite element method(FEM)analyses.The results indicate that the addition of reinforcement layers to sandwich structures can significantly enhance the compressive yield strength and energy absorption capacity of porous metal structures;Micro-CT in-situ observation shows that the strain of the porous structure without the reinforcing layer is concentrated in the middle region,while the strain of the porous structure with the reinforcing layer is uniformly distributed;FEM analysis reveals that the reinforcing layers can alter stress distribution and reduce stress concentration,thereby promoting uniform deformation of the porous structure.The addition of reinforcing layer increases the compressive yield strength of sandwich-structured composite materials by 124%under the condition of limited reduction of porosity,and the yield strength increases from 4.6 to 10.3 MPa.

Virtual rutting test of asphalt mixture using discrete element method

In order to investigate the permanent deformation behavior of asphalt mixtures from discontinuity, the virtual rutting test of asphalt mixtures is developed by the discrete element method （DEM）. A digital specimen generation procedure considering aggregate gradation and irregular shape is developed based on the probability theory and the Monte Carlo method. The virtual rutting test is then conducted based on the generated digital specimen. In addition, on the basis of the time-temperature superposition （TTS） principle, a calculation method is used to reduce the computation time of the virtual rutting test. The simulation results are compared with the laboratory measurements. The results show that the calculation method based on the TFS principle in the discrete element （DE） viscoelastic model can significantly reduce the computation time. The deformation law of asphalt mixtures in the virtual rutting test is similar to the laboratory measurements, and the deformation and the dynamic stability of the virtual rutting test are slightly greater than the laboratory measurements. The two-dimensional virtual rutting test can predict the permanent deformation performance of asphalt mixtures.

Discrete element and finite element coupling simulation and experiment of hot granule medium pressure forming

The granule medium of discreteness is supposed to be continuous（Drucker-Prager model） in the existing finite element simulation analysis on the hot granule medium pressure forming（HGMF） process, so the granule medium may produce tensile stress in the process of pressure-transferring and flowing, which does not coincide with the reality. The analysis method, discrete element and finite element（DE-FE） coupling simulation, is proposed to solve the problem. The material parameters of simulation model are obtained by the pressure-transfer performance test of granule medium and the hot uniaxial tensile test of sheet metal. The DE-FE coupling simulation platform is established by adopting Visual Basic language. The features in the process that AA7075-T6 conical parts are formed by the HGMF process are analyzed and verified by the process test. The studies show that the results of DE-FE coupling simulation coincide well with the test results, which provides a new analysis method to solve the mechanics problem in the coupling of discrete and continuum.

Numerical analysis of coupled finite element with element-free Galerkin in sheet flexible-die forming

A numerical method for coupled deformation between sheet metal and flexible-die was proposed. Based on the updated Lagrangian （UL） formulation, the elastoplastic deformation of sheet metal was analyzed with finite element method （FEM） and the bulk deformation of flexible-die was analyzed with element-free Galerkin method （EFGM）. The frictional contact between sheet metal and flexible-die was treated by the penalty function method. The sheet elastic flexible-die bulging process was analyzed with the FEM-EFGM program for coupled deformation between sheet metal and bulk flexible-die, called CDSB-FEM-EFGM for short. Compared with finite element code DEFORM-2D and experiment results, the CDSB-FEM-EFGM program is feasible. This method provides a suitable numerical method to analyze sheet flexible-die forming.

Equal channel angular extrusion of NiTi shape memory alloy tube

As a new attempt, equal channel angular extrusion （ECAE） of nickel-titanium shape memory alloy （NiTi SMA） tube was investigated by means of process experiment, finite element method （FEM） and microscopy. NiTi SMA tube with the steel core in it was inserted into the steel can during ECAE of NiTi SMA tube. Based on rigid-viscoplastic FEM, multiple coupled boundary conditions and multiple constitutive models were used for finite element simulation of ECAE of NiTi SMA tube, where the effective stress field, the effective strain field and the velocity field were obtained. Finite element simulation results are in good accordance with the experimental ones. Finite element simulation results reveal that the velocity field shows the minimum value in the corner of NiTi SMA tube, where severe shear deformation occurs. Microstructural observation results reveal that severe plastic deformation leads to a certain grain orientation as well as occurrence of substructures in the grain interior and dynamic recovery occurs during ECAE of NiTi SMA tube. ECAE of NiTi SMA tube provides a new approach to manufacturing ultrafine-grained NiTi SMA tube.

原型理论对发展二语词汇习得策略的启发

NanJiang修正了Levelt话语生成模型,并且将之运用于二语习得中词汇习得的过程,本文试图利用认知语言学中的原型理论对该模型进行进一步修正,以期得到一个适合描述二语词汇习得过程的动态模型.

Grain statistics effect on deformation behavior in asymmetric rolling of pure copper foil by crystal plasticity finite element model

The grain statistics effect was investigated through asymmetric rolling of pure copper foil by a realistic polycrystalline aggregates model and crystal plasticity element finite model.A polycrystalline aggregate model was generated and a crystal plasticity-based finite element model was developed for each grain and the specimen as a whole.The crystal plasticity model itself is rate dependent and accounts for local dissipative hardening effects and the original orientation of each grain was generated based on the orientation distribution function（ODF）.The deformation behaviors,including inhomogeneous material flow,decrease of contact press and roll force with the increase of grain size for the constant size of specimens,were studied.It is revealed that when the specimens are composed of only a few grains across thickness,the grains with different sizes,shapes and orientations are unevenly distributed in the specimen and each grain plays a significant role in micro-scale plastic deformation and leads to inhomogeneous deformation and the scatter of experimental and simulation results.The slip system activity was examined and the predicted results are consistent with the surface layer model.The slip band is strictly influenced by the misorientation of neighbor grain with consideration of slip system activity.Furthermore,it is found that the decrease of roll force and the most active of slip system in surface grains are caused by the increase of free surface grain effect when the grain size is increased.The results of the physical experiment and simulation provide a basic understanding of micro-scaled plastic deformation behavior in asymmetric foil rolling.

Sheet Metal Forming Simulation and Its Application in Stamping Process of Automobile Panels

The paper starts with a brief overview to the necessity of sheet metal forming simulation and the complexity of automobile panel forming, then leads to finite element analysis (FEA) which is a powerful simulation tool for analyzing complex three-dimensional sheet metal forming problems. The theory and features of the dynamic explicit finite element methods are introduced and the available various commercial finite element method codes used for sheet metal forming simulation in the world are discussed,and the civil and international status quo of automobile panel simulation as well. The front door outer panel of one certain new automobile is regarded as one example that the dynamic explicit FEM code Dynaform is used for the simulation of the front door outer panel forming process. Process defects such as ruptures are predicted. The improving methods can be given according to the simulation results. Foreground of sheet metal forming simulation is outlined.

Study on the Morphological Differences of Four Carp Populations

[Objective] The aim was to discuss the morphological differences of four carp populations.[Method] Based on traditional morphological data（including countable and measurable characters） and framework data,the morphological differences and phylogenesis of Yellow River carp population（YR）,wild four-naris carp population（WF）,farmed four-naris carp population（FF） and carp population from Suzhou section of Wusong River（WR） were studied by means of multivariate analysis.[Result] There was no significant difference（P〉0.05） in countable characters among four carp populations.Discriminant analysis showed the discriminating accuracy of YR,WF,FF and WR population were 87.5%,78.1%,73.5% and 96.8% respectively,and the synthetic discriminating accuracy of four populations was up to 83.7%.In addition,cluster analysis revealed that YR population and WF population clustered together,while FF population and WR population clustered together.Principal component analysis indicated that the morphological differences among four populations mainly came from the head,tail and vertical axis of fish.[Conclusion] The study could provide theoretical foundations for the purification and rejuvenation of rare four-naris carp.

Identification of processing window for extrusion of large thick-walled Inconel 625 alloy pipes using response surface methodology

Identifying suitable processing window is necessary but difficult for achieving favorable microstructure and performance in extrusion of large thick-walled pipe with difficult-to-deform Inconel 625 alloy. In this work, a method was established for identifying the extrusion process window considering temperature control using response surface methodology. Firstly, the response surface models, which correlate temperature rise and peak temperature to key extrusion parameters, have been developed by orthogonal regression based on finite element calculated data. Secondly, the coupled effects of the key extrusion parameters on the temperature rise and peak temperature have been disclosed based on the regression models. Lastly, suitable extrusion processing windows, which are described by contour map of peak temperature in the space of extrusion speed and initial billet temperature, have been established for different extrusion ratios. Using the identified process window, a suitable combination of the key extrusion parameters can be determined conveniently and quickly.

Effects of Feed Fermentation on Chemical Fractionation of Trace Elements in Feed and Pig Manure and Skatole Content in Pig Manure

[Objective] This study aimed to promote the combination of cultivation and livestock farming, and to explore an environment-protecting farming style. [Method]The effects of anaerobically fermented complete compound sow feed, added with Lactobacillus and Bacillus subtilis, on the chemical fractionation of copper, iron, zinc and manganese in feed and pig manure and skatole content in pig manure were investigated. [Result] Compared with those in the non-fermented feed, in the fermented feed and pig manure, the acetic acid-extractable copper, iron, zinc and manganese contents increased significantly（P0.05）, the reduced copper and iron contents increased significantly（P 0.05）, the oxidized copper and iron contents reduced significantly（P0.05）, and the residual copper contents remained unchangeable（P0.05）. The pH value of fermented feed decreased significantly（P0.05）, and that of pig manure increased significantly（P0.05）. The skatole content in pig manure decreased significantly（P 0.01）. The Lactobacillus abundance and amylase and cellulase activity increased significantly（P 0.05）. [Conclusion] The fermentation of feed changed the chemical fractionation of copper, iron, zinc and manganese in feed and pig manure, and reduced the manure odor.

Flexible-die forming process with solid granule medium on sheet metal

Certain non-metallic granules （NMG） were selected as the research object. It was proposed to conduct the volume compression experiments as well as those on the NMG physical properties at high stress levels. Then, not only the volume compression ratio curve but also the extended Drucker-Prager linear model were obtained. In addition, through the friction strength tests, parameters of the Mohr-Coulomb model were gained, which proved in basic agreement with those of the extended Drucker-Prager linear model. Additionally, curves of the friction coefficients between the NMG and the sheet metal trader different pressures were also obtained. Based on the material performance experiments, numerical analysis in respect of flexible-die forming process with solid granule medium （SGM） was conducted. The die and device for experiments of solid granule medium forming （SGMF） on sheet metal were designed and manufactured. Typical parabolic parts were successfully trial-produced. The tests and simulation results show that the sheet formability is significantly improved for the extraordinary friction performance during interaction between the SGM and the sheet metal surface. The process control and die structure are simple, and the shaped work-pieces enjoy many advantages, such as satisfactory surface quality and favorable die fitability, which offers a brand-new method and means for processing and preparation of sheet metals.