IN-PLANE WAVE MOTION IN FINITE ELEMENT MODEL

The analysis method of lattice dynamics in classical physics is extended to study the properties of in-plane wave motion in the hybrid-mass finite element model in this paper. The dispersion equations of P and SV waves in the discrete model are first obtained by means of separating the characteristic equation of the motion equation, and then used to analyse the properties of P-and SV-homogeneous, inhomogeneous waves and other types of motion in the model. The dispersion characters, cut-off frequencies of P and SV waves, the polarization drift and appendent anisotropic property of wave motion caused by the discretization are finally discussed.

Study and application of monitoring plane displacement of a similarity model based on time-series images

In order to compensate for the deficiency of present methods of monitoring plane displacement in similarity model tests,such as inadequate real-time monitoring and more manual intervention,an effective monitoring method was proposed in this study,and the major steps of the monitoring method include:firstly,time-series images of the similarity model in the test were obtained by a camera,and secondly,measuring points marked as artificial targets were automatically tracked and recognized from time-series images.Finally,the real-time plane displacement field was calculated by the fixed magnification between objects and images under the specific conditions.And then the application device of the method was designed and tested.At the same time,a sub-pixel location method and a distortion error model were used to improve the measuring accuracy.The results indicate that this method may record the entire test,especially the detailed non-uniform deformation and sudden deformation.Compared with traditional methods this method has a number of advantages,such as greater measurement accuracy and reliability,less manual intervention,higher automation,strong practical properties,much more measurement information and so on.

The use of the greater trochanter marker in the thigh segment model:Implications for hip and knee frontal and transverse plane motion

Background:The greater trochanter marker is commonly used in 3-dimensional(3D) models;however,its influence on hip and knee kinematics during gait is unclear.Understanding the influence of the greater trochanter marker is important when quantifying frontal and transverse plane hip and knee kinematics,parameters which are particularly relevant to investigate in individuals with conditions such as patellofemoral pain,knee osteoarthritis,anterior cruciate ligament(ACL) injury,and hip pain.The aim of this study was to evaluate the effect of including the greater trochanter in the construction of the thigh segment on hip and knee kinematics during gait.Methods:3D kinematics were collected in 19 healthy subjects during walking using a surface marker system.Hip and knee angles were compared across two thigh segment definitions(with and without greater trochanter) at two time points during stance:peak knee flexion(PKF) and minimum knee flexion(Min KF).Results:Hip and knee angles differed in magnitude and direction in the transverse plane at both time points.In the thigh model with the greater trochanter the hip was more externally rotated than in the thigh model without the greater trochanter(PKF:-9.34°± 5.21° vs.1.40°± 5.22°,Min KF:-5.68°± 4.24° vs.5.01°± 4.86°;p < 0.001).In the thigh model with the greater trochanter,the knee angle was more internally rotated compared to the knee angle calculated using the thigh definition without the greater trochanter(PKF:14.67°± 6.78° vs.4.33°± 4.18°,Min KF:10.54°± 6.71° vs.-0.01°± 2.69°;p < 0.001).Small but significant differences were detected in the sagittal and frontal plane angles at both time points(p < 0.001).Conclusion:Hip and knee kinematics differed across different segment definitions including or excluding the greater trochanter marker,especially in the transverse plane.Therefore when considering whether to include the greater trochanter in the thigh segment model when using a surface markers to calculate 3D kinematics for movement assessment,it is important to have a clear understanding of the effect of different marker sets and segment models in use.

Numerical study on turbulent mixed convection in a vertical plane channel using hybrid RANS/LES and LES models

Two Delayed-Detached Eddy Simulation(DDES) models, and a Large-Eddy Simulation(LES) model are used to investigate the turbulent flows and mixed convection between a hot plate and a cold plate via the software FLUENT. The two DDES models include Production-limited DDES(PL-DDES) and Improved DDES(IDDES) models.The Wall-Adapting Local Eddy-Viscosity(WALE) model is the used LES model. The numerical computations are performed at Reynolds number Reb= 4494 and different Richardson numbers Ri = 0.025, 0.048, 0.1. The comparing data is from the Direct Numerical Simulation(DNS) at Reb= 4494 and Ri = 0.048. The comparison reveals that the two DDES models have better performance in predicting time-averaged parameters than the WALE model in the aiding flow. The best predicted time-averaged results are obtained by the PL-DDES model in the opposing flow. Furthermore, the results of different Ri obtained by the PL-DDES model agree well with the DNS data.

Anisotropic Plane Symmetric Two-Fluid Cosmological Model with Time-Varying G and A

We investigate a two-fluid anisotropic plane symmetric cosmological model with variable gravitational constant G（t） and cosmological term A（t）. In the two-fluid model, one fluid is chosen to be that of the radiation field modeling the cosmic microwave background and the other one a perfect fluid modeling the material content of the universe. Exact solutions of the field equations are obtained by using a special form for the average scale factor which corresponds to a specific time-varying deceleration parameter. The model obtained presents a cosmological scenario which describes an early acceleration and late-time deceleration. The gravitation constant increases with the cosmic time whereas the cosmological term decreases and asymptotically tends to zero. The physical and kinematical behaviors of the associated fluid parameters are discussed.

Review on dynamic analysis of road pavements under moving vehicles and plane strain conditions

This paper reviews works on the dynamic analysis of flexible and rigid pavements under moving vehicles on the basis of continuum-based plane strain models and linear theories.The purpose of this review is to provide in-formation about the existing works on the subject,critically discuss them and make suggestions for further research.The reviewed papers are presented on the basis of the various models for pavement-vehicle systems and the various methods for dynamically analyzing these systems.Flexible pavements are modeled by a homogeneous or layered half-plane with isotropic or anisotropic and linear elastic,viscoelastic or poroelastic material behavior.Rigid pavements are modeled by a beam or plate on a homogeneous or layered half-plane with material properties like the ones for flexible pavements.The vehicles are modeled as concentrated or distributed over a finite area loads moving with constant or time dependent speed.The above pavement-vehicle models are dynamically analyzed by analytical,analytical/numerical or purely numerical methods working in the time or frequency domain.Representative examples are presented to illustrate the models and methods of analysis,demonstrate their merits and assess the effects of the various parameters on pavement response.The paper closes with con-clusions and suggestions for further research in the area.The significance of this research effort has to do with the presentation of the existing literature on the subject in a critical and easy to understand way with the aid of representative examples and the identification of new research areas.

Exploration of Water Resource and Multiple Model for Water Resource Development in Karst Areas with the Preferred Plane Theory

According to the theory of preferred plane, preferred planes (faults) alwayscontrol the distribution of bedrock fissure water and hold abundant groundwater. Thus, theexploration of fissure or karst water can be converted into searching for the watery preferred plane(WPP). In the paper, the characteristic of watery preferred planes is analyzed and a series ofsuperior indices has been set up. It is introduced that WPPs are determined by the methods ofgeological analysis, superior index and complex geophysical analysis. Meanwhile, new multiple modelfor water resource development in the water-scarce areas of karst mountainous regions are advanced.

Modeling Walking with an Inverted Pendulum Not Constrained to the Sagittal Plane. Numerical Simulations and Asymptotic Expansions

Inverted pendulum models are commonly used to study the bio-mechanics of biped walkers. In its simplest form, the inverted pendulum consists of a point mass attached to two straight mass-less legs. Most works constrain the motion of the mass to the sagittal plane, i.e. the plane perpendicular to the ground that contains the direction toward the biped is walking. In this article, we remove this constrain to study the oscillations, the mass experiences in the direction perpendicular to the sagittal plane as the biped walks. While small, these lateral oscillations are unavoidable and of importance in the understanding of balance and stability of walkers, as well as walkers induced oscillations in pedestrian bridges.

Modeling of Plane Arrays Using a Variational Approach

The variational statement of synthesis problem is generalized in order to account the additional requirements to the synthesized radiation pattern (RP) and field distribution in the specified points of near zone. For this aim, the minimizing functional is supplemented by term providing the possibility to minimize the values of field in these points;creating the deep zeros in the RP for the certain angular coordinates is realized too. The approach foresees reduction of an explicit formula for field values in a near zone. The results of computational modeling testify the possibility to create zeros in the given RP and to minimize the values of field in a near zone of plane arrays in a great extent.

中低温岩浆热液型金矿床找矿预测地质模型

我国金矿资源对外依存度长期居高不下,立足国内,寻找并探明一批大型金矿床是一项迫在眉睫的重大任务。中低温岩浆热液型金矿床是我国金的最主要来源,如何寻找其隐伏矿和深部矿成为当前矿产勘查研究的热点。本文以勘查区找矿预测理论为指导,以中低温岩浆热液型金矿床为研究对象,总结了中低温岩浆热液型金矿床地质特征,构建了以成矿地质体、成矿构造和成矿结构面特征和成矿作用特征标志为核心内容的找矿预测地质模型,为该类型金矿床找矿预测提供了新的思路,指导隐伏矿和深部矿金资源勘查取得突破。中低温岩浆热液型金矿床分为中温岩浆热液型金矿床和低温岩浆热液型金矿床两个亚类,广泛发育于陆块区和造山带中,赋矿围岩多种多样,成矿时代广泛,主要集中在中生代。本文厘定了中低温岩浆热液型金矿床成矿地质体为中酸性侵入体,与矿床(体)呈现出空间上相依(1~5km)、时间上相近(10Myr)、成因上相关的内在成生联系和时空配置关系。成矿构造属褶皱、断裂、岩浆侵入复合构造系统;成矿结构面主要有断裂、硅钙面、岩溶构造及岩体侵入接触带、爆破角砾岩体及水压裂隙等;矿化样式受成矿结构面控制,大致可分为四个类型:层状、脉状、块状及其组合而成的复合型。中温岩浆热液型金矿床成矿作用早阶段温度可达450℃左右,形成强度不等的钾长石化、钠长石化或铁白云石化;主成矿阶段成矿温度250℃左右,蚀变主要为硅化、绢云母化、伊利石化,Au和Ag共伴生,同时伴生少量Pb、Zn、Cu等,主要金属矿物为黄铁矿,次为黄铜矿、磁黄铁矿、方铅矿和闪锌矿;而低温岩浆热液型金矿床成矿作用主阶段温度低于250℃,Au和As、Sb共伴生,Ag含量低,常见毒砂和辉锑矿等矿物,成矿作用早阶段蚀变则主要为硅化,有的为次生石英岩化。金的沉淀富集机制包括流体的沸腾、混合和交代等机制。成矿作用中心位于岩体外接触带2~3km和接触带之内,由浅部到深部形成“上脉下层”的二元结构模式,脉状矿体具有侧伏延深规律,在此基础上构建了找矿预测地质模型。在该模型指导下,我们重新厘定了我国重要成矿区带金矿床类型,在深部发现新的矿体样式,拓宽了深部找矿空间,提升了我国重要成矿区带成矿规律的认识水平,带动了我国重要成矿区带金矿找矿新突破。

基于X-Plane的某巡飞弹快速原型及一体化建模

针对巡飞弹前期设计验证过程中,数学建模及气动参数分析方法研发难道大、周期长等问题,提出采用X-Plane的快速原型及一体化建模方法。分析巡飞弹的特点并总结了各类仿真方法的运行机制,分析了X-Plane的原理;通过机体建模实现了巡飞弹不依赖于数学模型及气动参数的快速原型搭建,改进了翼型及桨叶设计,实现了特殊控制(混控、伞降及折叠翼);通过软件在回路仿真方法验证了飞行器设计及控制器性能。研究成果表明:该方法能够实现各类飞行器前期快速原型设计及验证,具有研发周期短,可视化效果好等特点,对飞行器设计及控制算法研究人员均有借鉴意义。

HYPERSTATIC STRUCTURE MAPPING MODEL BUILDING AND OPTIMIZING DESIGN

Hyperstatic structure plane model being built by structural mechanics is studied. Space model precisely reflected in real stress of the structure is built by finite element method （FEM） analysis commerce software. Mapping model of complex structure system is set up, with convenient calculation just as in plane model and comprehensive information as in space model. Plane model and space model are calculated under the same working condition. Plane model modular construction inner force is considered as input data; Space model modular construction inner force is considered as output data. Thus specimen is built on input data and output dam. Character and affiliation are extracted through training specimen, with the employment of nonlinear mapping capability of the artificial neural network. Mapping model with interpolation and extrpolation is gained, laying the foundation for optimum design. The steel structure of high-layer parking system （SSHLPS） is calculated as an instance. A three-layer back-propagation （BP） net including one hidden layer is constructed with nine input nodes and eight output nodes for a five-layer SSHLPS. The three-layer structure optimization result through the mapping model interpolation contrasts with integrity re-analysis, and seven layers structure through the mapping model extrpulation contrasts with integrity re-analysis. Any layer SSHLPS among 1-8 can be calculated with much accuracy. Amount of calculation can also be reduced if it is appfied into the same topological structure, with reduced distortion and assured precision.

Similarity model tests of movement and deformation of coal-rock mass below stopes

For a study of the movement and deformation of coal-rock mass and low protected seams below a stope,as well as for fracture developments and rules of evolution of permeability,we designed a plane strain model test stand to carry out model tests of similar materials in order to improve the effect of gas drainage from low protected seams and to measure the movement and deformation of coal-rock mass using a method of non-contact close-range photogrammetry.Our results show that 1) using paraffin melting to take the place of coal seam mining can satisfy the mining conditions of a protective seam;2) coal-rock mass under goafs has an upward movement after the protective seam has been mined,causing floor heaving;3) low protected seams become swollen and deformed,providing a good pressure-relief effect and causing the coal-rock mass under both sides of coal pillars to become deformed by compression and 4) the evolution of permeability of low protected seams follows the way of initial values→a slight decrease→a great increase→stability→final decrease.Simultaneously,the coefficient of air permeability increased at a decreasing rate with an increase in interlayer spacing.

ELASTIC-PLASTIC CRACK GROWTH ON PLANE STRAIN BIMATERIAL INTERFACE

Finite element computations are carried out to simulate plane strain crack growth on a bimaterial interface under the assumption of small scale yielding.The modified Guron constitutive equation and the element vanish technique introduced by Tvergaard et al.are used to model the final formation of an open crack.It is found from the calculation that the critical fracture toughness for crack growth is much low- er in bimaterials than that in homogeneous material.The critical fracture toughness is strongly dependent on material properties of the bimaterial pair and the mixed mode of remote loads.The interface crack grows in the more compliant(lower hardening)material or in the weaker(lower yield strength)material.In Mode-Ⅰ loading,the crack grows zigzag along the interface.

2D Plane辅助NURBS建模在轨道列车中的应用

NURBS是一种计算机辅助设计中表达曲线曲面的方式,也是Rhino软件的核心功能。本文以轨道列车模型为例,使用2D Plane辅助NURBS三维建模方法快速创建轨道列车三维模型,通过实操分析NURBS方法搭配2D Plane在轨道列车建模中的技巧,为NURBS方法在工业设计领域同类产品建模中的应用提供参考。

The Ratcheting Behaviour of Stainless Steel Pressurized Piping Elbows Subjected to Dynamic Out-of-Plane Moments

In this paper the ratcheting behavior of four pairs of stainless steel elbows is studied under conditions of steady internal pressure and dynamic conditions that induced out-of-plane external moments at frequencies typical of seismic excitations. The finite element analysis with the nonlinear kinematic hardening model has been used to evaluate ratcheting behavior of the piping elbows under mentioned loading condition. Material parameters have been obtained from several stabilized cycles of specimens that are subjected to symmetric strain cycles. The direction of maximum strain is at about 45° between the hoop and axial directions. The results show that the direction of highest ratcheting is along the hoop direction rather than the direction of maximum principal strain. Also, the initial rate of ratcheting is large and then it decreases with the increasing cycles. Also, the FE method gives over estimated values compared with the experimental data.

单镜头倾斜摄影测量技术的应用及精度分析

针对5镜头无人机摄影测量技术在水利工程中的限制,提出一种单镜头无人机采用5航线倾斜测量法,对水利工程进行多角度拍摄,快速建立水利工程实景三维模型的方法。通过对三维模型的平面精度、高度精度进行误差分析,证明消费级无人机在多航线飞行方案下建立的水利工程实景三维模型满足现行《水利水电工程测量规范》和《三维地理信息模型数据产品规范》。

考虑超临界CO_(2)损伤的椭球形三维裂缝计算新模型

目前超临界CO_(2)压裂研究成果多集中于室内岩石损伤机理和劣化力学参数测试,对压裂形成的三维裂缝形态研究较少。为刻画超临界CO_(2)压裂过程的裂缝形态展布,基于Griffith断裂力学理论,建立了平面应变条件下椭球形裂缝扩展的三维计算新模型;结合前人室内测试结果,回归了岩石弹性力学参数与超临界CO_(2)多浸泡因素关联式,讨论了超临界CO_(2)压力、温度、施工排量、初始弹性模量、初始泊松比、缝内净压力、储层厚度等参数对裂缝扩展形态的影响。结果表明:针对上下存在水层的目的层采用超临界CO_(2)压裂时更应采取控缝高的措施;针对低渗储层,可优先考虑超临界CO_(2)压裂;超临界CO_(2)压裂工艺更适用于最小水平主应力大的储层;超临界CO_(2)压裂时,有助于低排量下获得相同的平均缝宽。研究成果对非常规油气水平井超临界CO_(2)压裂裂缝参数优化具有重要意义。

A NEW ENGINEERING CALCULATING MODEL FOR A LINEAR INCLUSION AND ITS APPLICATIONS

By using the hypothesis of the deformation of the straight bar and beam in mechanics of materials,a new engineering calculating model for a linear inclusion in plane is presented.Through the Kelvin's solution of a concentrated force,the inclusion problem is reduced to solving a set of uncoupled singular integral equations which can be solved by the numerical method of singular integral equation.Based on these results,several applicable examples including an inclusion-crack problem are calculated and the results are quite satisfactory.

基于服装造型设计的变形与转换探究

文章通过借助众多创新、前沿的服装造型设计实例为依据,从服装外形方面出发,对服装造型的内部构造及外部轮廓的变形与转换原理进行深入探究。以平面裁剪为视角,结合具体案例分析对服装版型的变换与解构,并针对设计师在规则与不规则的几何服装造型中的廓型转换与结构工艺进行探讨,探究在人-服装-环境概念下,设计师如何通过改变服装基础结构向功能性方向变换,增加服装的附加价值。通过梳理服装造型变换所包含的各种设计形态,详尽剖析各种变形手法,预见服装产业的造型设计发展方向。