对麦秸板弹性模量和阻尼比的动、静态法的测定与研究

弹性模量E和阻尼比ξ是衡量麦秸板材料物理力学性能的两个重要指标。由于表征动态系统的两个关键动态特征参数为阻尼比ξ和固有频率ωn,为此本文主要运用动态测试法测定麦秸板的纵向弹性模量值E及其阻尼比值ξ,并与静态法试验结果进行比较。

岩体动静参数测试及其关系研究

依据钻孔岩芯、钻孔电视录像可直观定性判定岩体质量,实施声波测井可准确测定岩体纵波速度,根据可靠的声波测试成果结合对岩芯、孔内录像的直观分析可判断易受多种因素影响的孔内岩体静弹模测试值的可靠度,从而去伪存真,建立有效的动、静参数相关式。对某工程钻孔原位测试所获岩体动、静参数的空间分布特征和相关性等的研究结果表明,岩体的动、静参数与岩体的岩性、结构面发育情况和风化程度等密切相关,其相关式不仅可将大量的声波测试成果转化为静弹性模量,为建基面确定、坝基岩体质量分级、稳定性评价及静弹模分区、应力分析和三维设计提供实用指标,还可供类似地质区域借鉴。

岩体中弹性波速度及其应用研究

从岩体弹性波的传递速度入手，分析岩体中影响弹性波速度的因素有岩体弹性波频率、视速度（除了射线方向以外的任意方向观测到的波速）、岩体中的含水量差异、岩体的结构构造等。用岩体中测得的弹性波速值对岩体的质量进行评价时必然会出现什么是岩体弹性波的真波速及如阿评价和处理测得的弹性波波速值？采用什么方法评价岩体质量？等问题。在明确视速度概念的扩展、岩体弹性波速、岩石弹性波速、岩体的完整性系数几个名词的含义基础上，建议进行岩体质量评价中，采用岩体的完整性对岩体进行结构分类，列出了岩体的完整系数与岩体结构类型、工程地质特征的对应关系。根据岩体波速与岩体力学参数的关系，给出了计算岩体的静弹模和岩体抗压强度的经验公式。

地震波测试技术在十三陵蓄能电站工程验收中的应用

介绍了地震波测试技术在钻孔中测试地层动弹模的原理、方法及效果，并计算出静弹模，为工程的质量评价和验收提供了依据。

田湾核电站基岩变形参数测试与分析

分别采用常规室内试验及现场钻孔弹模试验方法对田湾核电站基岩的静弹模进行了测试 ,扼要介绍了钻孔弹模测试原理及测试结果。经对比分析可得以下结论 :(1)现场测试结果受裂隙的影响较大 ;(2 )对于完整岩石 ,两种测试结果基本一致。

基础固结灌浆效果检测方法的应用分析

介绍了目前国内外大坝基础固结灌浆效果检测常用的方法 ,以及各种检测方法的检测原理、适用范围及优缺点。

小干沟岩体E_d、E_s相关分析与机理讨论

本文通过对小干沟水电站花岗斑岩岩体的动弹模与静弹模相关分析,找到了该地区该种岩体E_dE_s呈线性关系。经验式为:E_s=0.505E_d。并通过国内外11条相关曲线的对比,对E_d与E_s间的关系及其规律,进行了一些讨论。初步提出,今后在岩体动、静弹模的关系研究上,应将复杂的,种类繁多的岩体统一在岩体质量这一概念下来进行。本文在此以为抛砖引玉。

Firmness evaluation of melon using its vibration characteristic and finite element analysis

The “Huang gua” melons were measured for their physical properties including firmness and static elastic modulus. The vibrational characteristics of fruits and vegetables are governed by their elastic modulus (firmness), mass, and geometry. Therefore, it is possible to evaluate firmness of fruits and vegetables based on their vibrational characteristics. Analysis of the vibration responses of a fruit is suggested for measuring elastic properties (Firmness) non-destructively. The impulse response method is often used to measure firmness of fruits. The fruit was excited using three types of balls (wooden, steel and rubber) and the vibration is detected by an accelerometer. The Instron device was used to measure the static elastic modulus of the inner, middle and outer portions of melon flesh. Finite element (FE) technique was used to determine the optimum excitation location of the chosen measurement sensor and to analyze the mode shape fruits. Four types of mode shapes (torsional or flexural mode shape, first-type, second-type spherical mode and breathing mode shape) were found. Finite element simulation results agreed well with experimental results. Correlation between the firmness and resonant frequency (r2=0.91) and between the resonant frequency and stiffness factor (r2=0.74) existed. The optimum location and suitable direction for excitation and response measurement on the fruit were suggested.

A Statistical Analysis of the Modulus of Elasticity and Compressive Strength of Concrete C45/55 for Pre-stressed Precast Beams

Random behavior of concrete C45/55 XF2 used for prefabricated pre-stressed bridge beams is described on the basis of evaluating a vast set of measurements. A detailed statistical analysis is carried out on 133 test results of cylinders 150 ~ 300 mm in size. The tests have been running in laboratories of the Klokner Institute. A single worker took all specimens throughout the period, and the subsequent measurements of the static modulus of elasticity and the compressive strength of the concrete were performed. The measurements were made at the age of 28 days after specimens casting, and only one testing machine with the same capping method was used. Suitable theoretical models of division are determined on the basis of tests in good congruence, with the use of Z2 and the Bernstein criterion. A set of concrete compressive strength （carried out on 133 test results of cylinders 150 ~ 300 mm after test of static modulus of elasticity） shows relatively high skewness in this specific case. This cause that limited beta distribution is better than generally recommended theoretical distribution for strength the normal or lognormal. The modulus of elasticity is not significantly affected due to skewness because the design value is based on mean value.

Wind-induced responses of super-large cooling towers

Traditional gust load factor(GLF)method,inertial wind load(IWL)method and tri-component method(LRC+IWL)cannot accurately analyze the wind-induced responses of super-large cooling towers,so the real combination formulas of fluctuating wind-induced responses and equivalent static wind loads(ESWLSs)were derived based on structural dynamics and random vibration theory.The consistent coupled method(CCM)was presented to compensate the coupled term between background and resonant response.Taking the super-large cooling tower(H=215 m)of nuclear power plant in Jiangxi Province,China,which is the highest and largest in China,as the example,based on modified equivalent beam-net design method,the aero-elastic model for simultaneous pressure and vibration measurement of super-large cooling tower is firstly carried out.Then,combining wind tunnel test and CCM,the effects of self-excited force on the surface pressures and wind-induced responses are discussed,and the wind-induced response characteristics of background component,resonant component,coupled term between background and resonant response,fluctuating responses,and wind vibration coefficients are discussed.It can be concluded that wind-induced response mechanism must be understood to direct the wind resistant design for super-large cooling towers.

Static-deformation based fault diagnosis for damping spring of large vibrating screen

Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS.

Static Stability Analysis of a Single Planar Object Grasped by a.Multifingered Hand

In this study, the static stability of the grasp of a single planar object is analyzed using the potential energy method. In previous papers, we considered cases in which individual fingers were replaced by a multidimensional translational spring model, in which each finger is constructed with prismatic joints. Human hands and the most developed mechanical hands are constructed with revolute joints. In this paper, the effects of fingertip rotation and a revolute joint spring model are investigated. A grasp stiffness matrix is analytically derived by considering not only frictional rolling contact but also frictionless sliding contact. The difl＇erence between the frictional stiffness matrix and the frictionless one is analytically obtained. The effect of local curvature at contact points is analytically derived. The grasp displacement directions affected by the change in curvature and the contact condition are also obtained. The derived stiffness matrix of the revolute joint model is compared with that of the prismatic joint model, and then the stiffness relation is clarified. The gravity effect of the object is also considered. The effectiveness of our method is demonstrated through numerical examples. The stability is evaluated by the eigenvalues of the grasp stiffness matrix, and the grasp displacement direction is obtained by the corresponding eigenvectors. The effect of joint angle is also discussed.

Macro Model Study for Nonlinear Spring of Tense Torsion Bar in Gap-Closing Type Electrostatic Micromirror

Nonlinear spring characteristics of the tense torsion bar in the gap-closing type electrostatic micromirror are examined. The macro model is introduced for the experimental study. The tension applied in the torsion bar is well controlled using the electromagnetic attraction. This controllability is suited for clearing the nonlinear nature. The tension is confirmed to have the effect to widen the controllable angle range of the mirror suppressing the pull-in. The pull-in angle is observed to increases to about 74% of the mechanical limit angle at the tension of 0,96 N. This is significantly larger than 44% of the case with the linear spring. The larger resonant frequency is maintained. The hardening of the spring can keep the balance with the electrostatic force over the limit of the linear spring. The observed features are explained reasonably with the combination of twisting and bending displacements of the torsion bar.

Higher Order Multipole Potentials and Electrostatic Screening Effects on Cohesive Energy and Bulk Modulus of Metallic Nanoparticles

Higher order rnultipole potentials and electrostatic screening effects are introduced to incorporate the dan gling bonds on the surface of a metallic nanopaticle and to modify the coulornb like potential energy terms, respectively. The total interaction energy function for any rnetallic nanoparticle is represented in terms of two- and three-body potentials. The two-body part is described by dipole-dipole interaction potential, and in the three-body part, triple-dipole （DDD） and dipole-dipole-quadrupole （DDQ） terrns are included. The size-dependent cohesive energy and bulk modulus are observed to decrease with decreasing sizes, a result which is in good agreement with the experimental values of Mo and W nanoparticles.

A method for static aeroelastic analysis based on the high-order panel method and modal method

A method for static aeroelastic analysis based on the high-order panel method and modal method is presented. The static aeroelastic characteristics of flexible wings are investigated using this method. Three-dimensional aerodynamic models of flexible wings are constructed based on the geometry of wing configuration, and the modal method is adopted to achieve the fluid-structure coupling. The static aeroelastic characteristics of the AGARD445.6 wing and a low-aspect-ratio wing are investigated in this study. The influences of elastic structural deformation on aerodynamic forces are studied with an emphasis analyzing the aerodynamic coefficients, wing root loads, structural deformation and pressure distribution of different sections, and results are compared with the results from wind-tunnel tests and the elastic results based on experimental aerodynamic forces. It is concluded that aerodynamic forces can be accurately calculated with the high-order panel method. The method presented in this study is feasible, credible and efficient. Comprehensive static aeroelastic characteristics can be provided by the method for early phases of aircraft design.

The Micro-foundations of the Environmental Kuznets Curve

This paper presents a simple and straight-forward static model of the micro-foundations of the environmental Kuznets curve, in which the relationship between income and pollution depends on the relative magnitudes of the diminishing income-compensated price elasticity of environmental amenity and increasing marginal propensity to earn environmental amenity out of non-environment income. The smaller the income-compensated price elasticity and the larger the marginal propensity to earn out of non-environment income, the earlier the turning point emerges. This key feature of our model generalizes the specific features of many existing models and generates many of their implications.