单侧摩擦接触约束夹杂物与平面波的动力相互作用——时域边界元分析

应用时域边界元法研究了瞬态平面波对单侧摩擦约束夹杂物的散射问题 .假设界面摩擦遵守库仑定理 .当入射波足够强时界面会出现局部分离和滑移 .由于边界上的区域 (分离区、滑移区和粘着区)是未知的 ,所以该问题实际上是个复杂的边界非线性问题 .为了确定未知区域 ,该文发展了一种有效的迭代技术 .作为算例 。

物系约束下的加速度关联特征解析

物系约束下的加速度关联问题是竞赛或北清校考的常见问题.对于加速度在法线方向是否具有相同的分量,很多学生容易因思维定势做出错误判断,得出错误结论.现针对此类问题,本文尝试通过一道具体连接体问题的求解,从不同角度分析得出加速度相关问题的解决方案,以期帮助学生进一步阐述物系约束下的加速度关联特征.

基于物方几何约束的多视匹配算法研究

影像匹配是航空影像数据自动空三处理的关键技术之一。为充分利用三线阵影像信息及纹理信息,文中针对ADS40影像采用一种利用像方和物方信息进行约束的多视匹配方法,此算法能同时处理3张及3张以上的影像,大大加快匹配效率,为自动空三提供有效的连接点及为提取DSM提供高精度密集匹配点。

附加物方长度约束的三维坐标交会测量

大型粒子加速器等精密工程在加工制造及设备安装等方面对空间三维坐标精度提出了极高的要求,在利用多路绝对激光测距仪进行多边交会测量空间点三维坐标的基础上,在物方(目标点所在物体)上附加高精度长度约束以进一步提高点位精度。以多路绝对激光测距仪的高精度绝对测距性能为基础,通过已建立的三维测边网及免自标定的激光多边交会测量平差模型,得到高精度的目标点空间三维坐标。在此基础上,附加涵盖目标点信息的物方长度约束,建立对应的附有条件的参数平差模型,进行平差解算。实验分析表明,在多边交会测量基础上附加物方长度约束,可提高物方目标点坐标的精度,在8 m×3.5 m×2.5 m的整体实验范围内,点位精度最高提升0.74μm,较原精度提升27.0%。该方法可操作性强,可用于现代装备制造业中高精度大尺寸坐标测量。

一车多件货物装载布局优化模型与算法

以三维多层货物装载布局问题为研究对象,结合货物运输安全特征,综合考虑装载货物合重心、总重量、总体积、车辆边界及货物之间不干涉等约束因子,以最大化承载车辆标记载重量和有效容积综合利用率为优化目标,建立一车多件货物装载布局优化模型。为保证货物布局的平整性和平衡性,提出基于人工装载经验的s中心骨架、带已布物群约束的布局、形状相似的概念,采用空间合并、融合、小块预留技术,在构造待布空间的匹配货物集、中心骨架及其移动策略的基础上设计一车多件货物装载布局优化算法。实例表明:所提出的模型和算法能快速制定合理的三维多层货物装载布局方案,有效运用承载车辆,满足货物运输安全的要求。

聚乙烯薄膜对可燃气云爆炸影响的实验研究与数值模拟

聚乙烯薄膜作为约束物 ,对可燃气云爆炸有着重要的影响 .采用 7 8%的乙炔 /空气混合气进行了实验研究 ,薄膜厚度分别为 0 0 2、 0 0 4mm和 0 0 6mm ,层数为 1～ 4层 .结果显示 ,当采用单层厚度 0 0 2mm的薄膜时 ,半径 0 5m的半球形气云爆炸可产生 2 4 10kPa的最大超压 ;厚度 0 0 6mm时 ,最大超压达到 3 6 4 2kPa ;薄膜层数为 4层时 ,最大超压上升到 13 12 5kPa .建立了描述气云爆炸的理论模型 ,模型考虑了薄膜强度、层数对爆炸的影响 ,采用SIMPLE算法进行了数值求解 .计算结果与实验值相比较 ,最大相对偏差 14 8% ,平均相对偏差 4 73% .提出的方法对有弱约束物存在时 ,气云爆炸的灾害预测具有重要的指导意义 .

3D electrical resistivity inversion using prior spatial shape constraints

To minimize the number of solutions in 3D resistivity inversion, an inherent problem in inversion, the amount of data considered have to be large and prior constraints need to be applied. Geological and geophysical data regarding the extent of a geological anomaly are important prior information. We propose the use of shape constraints in 3D electrical resistivity inversion, Three weighted orthogonal vectors （a normal and two tangent vectors） were used to control the resistivity differences at the boundaries of the anomaly. The spatial shape of the anomaly and the constraints on the boundaries of the anomaly are thus established. We incorporated the spatial shape constraints in the objective function of the 3D resistivity inversion and constructed the 3D resistivity inversion equation with spatial shape constraints. Subsequently, we used numerical modeling based on prior spatial shape data to constrain the direction vectors and weights of the 3D resistivity inversion. We established a reasonable range between the direction vectors and weights, and verified the feasibility and effectiveness of using spatial shape prior constraints in reducing excessive structures and the number of solutions. We applied the prior spatially shape-constrained inversion method to locate the aquifer at the Guangzhou subway. The spatial shape constraints were taken from ground penetrating radar data. The inversion results for the location and shape of the aquifer agree well with drilling data, and the number of inversion solutions is significantly reduced.

多台激光跟踪仪联合动态位姿测量精度评定方法研究

多台激光跟踪仪组网联合动态测量具有测量范围大、测量精度高、采样频率高的优点,在工业大尺寸动态位姿测量领域具有广泛的应用前景。目前激光跟踪仪动态测量精度评定主要针对单台激光跟踪仪,无法满足多台激光跟踪仪动态位姿测量精度评定的要求。文中提出基于物方先验约束条件的动态位姿测量精度评定方法,通过空间圆轨迹发生器和铟钢四面体,提供刚性约束条件和动态测量基准,实现对不同运动速度、不同采样频率的位姿测量精度进行评定。测试数据分析表明,基于物方先验约束条件的动态位姿测量精度评定方法能够有效的实现对测量精度的评定。

Binding Energy of Excitons in a Quantum Ring

The binding energy of excitons confined to a quantum ring under the influence of perpendicular homogeneous magnetic field is calculated as a function of the ring radius. Calculations are made by using the method of exact diagonalization within the effective-mass approximation. The feature of binding energy of the ground state as a function of the ring radius for several values of the magnetic field has been revealed. The interesting feature of our study is that, in a quantum ring, the geometric structure of exeitons may reveal transition.

Dynamical Model of QCD Vacuum and Quark Confinement

The phase transition of a simple local gauge model is investigated in terms of the Nambu–Jona-Lasinio mechanism and it is pointed out that the physical vacuum of QCD is bound state of quark-antiquark pairs which can be viewed, generally, as a nearly perfect color dia-electric medium. An important relation between the vacuum expectation value of gauge fields and scalar fields is also derived by solving the Euler equation for the gauge fields. Based on this relation the gauge potential is given which can be used to explain the asymptotic behavior and confinement of quarks in a hadron, and at the same time the Yukawa potential of strong interaction can be given too.

Vibration Spectra of Quasi-confined Optical Phonon Modes in an Asymmetric Wurtzite AlxGa1-xN/GaN/AlyGa1-yN Quantum Well

Based on the dielectric continuum model and Loudon＇s uniaxial crystal model, the properties of the quasi. confined （QC） optical phonon dispersions and the electron-QC phonons coupling functions in an asymmetric wurtzite quantum well （QW） are deduced via the method of electrostatic .potential expanding. The present theoretical scheme can naturally reduce to the results in symmetric wurtzite QW once a set of symmetric structural parameters are chosen. Numerical calculations on an asymmetric AlN/GaN/AIo,15 Gao.85N Wurtzite Q W are performed. A detailed comparison with the symmetric wurtzite QW was also performed. The results show that the structural asymmetry of wurtzite QW changes greatly the dispersion frequencies and the electrostatic potential distributions of the QC optical phonon modes.

Environmental Integration of Small Hydropower Development

On the basis of cooperative research with European professionals, problems relating to environmental and ecological protection were discussed while small hydropower development in China currently was introduced in this paper. Guidelines of small hydropower development dealing with environmental protection were sug- gested hereby. Various specific technical environmental solutions focusing on small hydropower development applied in European and other developed countries were also introduced in this paper. Main environmental solutions are discussed as follows： integrated design should be advocated during plan/design stage,＂ ecohydraulic engineering and its utilization in SHP design and construction; effective technical approaches to relieve and eliminate the impact of river interception and fix the reasonable minimum biological flow; environment-friendly mitigation and compensation measures for high/low-head hydropower schemes applied in diversion works, intake, nature-like fish-passes, penstock and powerhouse design; study and application of the new technology, material and equipments; launching renovation of environmental protection in existing stations; emphasiz- ing public participation and their acceptability for the SHP environment; coordinated inter-disciplinary study at national level, etc. Two case studies in Sweden and Australia are given here.

The Effect of Discharge Power on the Atmospheric Pressure Non-equilibrium Ar/O_2/TiCl_4 Plasma Deposition of TiO_2 Film

Deposition of TiO2 film from atmospheric pressure non- equilibrium Ar/O2/TiCl4 plasma was done to study the effect of discharge power during the film deposition process in this paper. TiO2 films with kinds of morphologies and controlled crystallization were deposited from mixtures of TiCl4 and O2 on quartz substrate by one step process. Scanning electron microscope （SEM） and transmission electron microscope （TEM） were used to analyze the morphology and crystallization of the deposited TiO2 films. It was found that the discharge power played a key role in the morphology and crystallization of the deposited TiO2 film whether the flow of TiCl4was large or small. When the flow of TiCl4 was large, the deposited TiO2 film was amorphous particles at low discharge power and was multi-crystalline at high discharge power. When the flow of TiCl4 was small, the deposited TiO2 film became more compact and the crystallization was enhanced as the discharge power increased. The dependence of the discharge current and the applied voltage with the discharge power indicated that it was a glow discharge. The gas temperature which increases with the discharge power is one of the main causes that affect the morphology and crystallization of the deposited film.

Study Under AC Stimulation on Excitement Properties of Weighted Small-World Biological Neural Networks with Side-Restrain Mechanism

In this paper, we propose a new model of weighted small-world biological neural networks based on biophysical Hodgkin-Huxley neurons with side-restrain mechanism. Then we study excitement properties of the model under alternating current （AC） stimulation. The study shows that the excitement properties in the networks are preferably consistent with the behavior properties of a brain nervous system under different AC stimuli, such as refractory period and the brain neural excitement response induced by different intensities of noise and coupling. The results of the study have reference worthiness for the brain nerve electrophysiology and epistemological science.

Statistical Study on Cement-Soil Mixture Strength

This paper presents an investigation on strength of cement deep mixing （CDM） mixture. Four typical works of offshore or land-based projects are introduced. With samples from these projects and laboratory tests, statistical analysis is made on the increment law of the strength of cement-soil mixture with different amount of cement, and strengths under different working conditions are compared. It is found that the amount of cement in the cement-soil mixture is closely related to the unconfined compressive strength of the mixture. At the age of 90 d,the unconfined compressive strength of the cement-soil mixture increased by 0.054 MPa—0.124 MPa with each cement increasing 10 kg/m3 in the cement-soil mixture, averagely increased by 0.085 MPa, while that at the age of 120 d increased by 1100 in comparison.The quality of the cement-soil mixture should be comprehensively evaluated in accordance with the trimmed average of strength, coefficient of variation and rock quality designation （RQD） indicators of sampling ratio.

Molecular Characterization and Expression and DNA Methylation Analyses of a Galectin-Related Protein Gene from Cynoglossus semilaevis

Galectins, a family of β-galactoside-binding proteins, participate in both innate immunity and adaptive immunity. This study identified one novel galectin-related protein from half-smooth tongue sole Cynoglossus semilaevis, which was designated as CsGRP. The full-length cDNA of its encoding gene was 785 bp in length with a 528 bp open reading frame encoding a putative protein of 176 amino acids. The deduced CsGRP contained a putative 131-aa galactoside-binding lectin domain and 3 critical residues responsible for carbohydrate binding （R93, W109 and R114）. Genomic structural analysis revealed that CsGRP consisted of five exons and four intzons. CsGRP showed 68% similarity with Poecilia latipinna GRP and 67% similarity wih Stegastes partitus GRP. CsGRP showed the highest expression level in liver, although its expression was detected in all tested tissues. When challenged with Vibrio harveyi, the expression of CsGRP was significantly down-regulated in liver （P〈 0.05）. In addition, we found that in spleen and kidney of C. semilaevis, the CpG island of CsGRP showed significantly higher （P 〈 0.05） methylation level in disease-resistant family of C. semilaevis （DR-Cs） than in disease-susceptible ones （DS-Cs）. Our results suggested that CsGRP may play important roles in the immune response of C. semilaevis. Moreover, DNA methylation patterns provided valuable data for understanding the relationship between epigenetic regulation and immunity, which would assist the animal genetic research and improve the animal breeding in the future.

对取消保值储蓄和降低存贷款利率问题的探讨

取消保值储蓄,降低存贷款利率,这两大措施的出台,无疑将对我国的经济生活产生重要影响.保值储蓄作为特殊时期的一种特殊措施是必要的、可取的,但作为一项长期政策来运用,有悖于市场经济的发展方向,保值储蓄主要解决部分存款负利率问题,利率杠杆是一种方便、灵活、有效的调节手段,它不但能解决保值补贴率所带来的直接效果,而且使利率杠杆的效率本身能得到充分发挥、利率市场化是金融改革的方向和必然归宿.

Bearing capacity of concrete filled bidirectional FRP tube subjected to axial compression

External confinement by fiber reinforced polymer (FRP) is an efficient technique to increase the bearing capacity and ductility of concrete. To better study the mechanical behavior of bidirectional FRP confined concrete, the yield criterion of bidirectional FRP is presented based on the static equilibrium condition in this paper, and a model for calculating the bearing capacity of bidirectional FRP confined concrete is established. The model can capture the character of bidirectional FRP confined concrete. Effects of the confinement effect coefficient, the unconfined concrete strength and the material properties of FRP on bearing capacity are analyzed. Results show that each parameter has different effects on the bearing capacity of bidirectional FRP confined concrete.

地质找矿勘查技术创新研究

针对现阶段我国地质找矿勘查技术的应用现状,进行有效分析,并简要介绍了地质找矿勘查技术原理、地质找矿勘查技术的应用原则,如创新性原则、以人为本原则、科学规划原则等,提出地质找矿勘查技术创新要点,希望能够给相关人员提供良好帮助。

Theoretical study on constitutive relationship of fiber reinforced polymer confined concrete

We proposed a bilinearity constitutive curve model of fiber reinforced polymer(FRP) confined concrete which includes a parabola in the first stage and a straight line in the second stage. The FRP-confined concrete has powerful confinement status and weak confinement status leading to different equations of parabola. We analyzed the impacts of factors such as confinement ratio and restrain stiffness on confined concrete compressive strength,ultimate strain and other control parameters through finite element analysis. The results show that the confinement ratio determines the confinement status,and the increase of the confinement ratio has a limited capacity to increase the compressive strength. The deformation of confined concrete is influenced by restrain stiffness. The stronger the restrain stiffness is,the less the lateral deformation is and the greater ultimate axial strain will be. The consideration of equivalent section coefficient kse is needed in the non-circular section confined concrete. We analyzed the results and proposed boundary values of strong and weak confinement styles,a peak/inflection point stress and strain model,and a compressive strength and ultimate strain model.