预应力混凝土连续梁桥振动特性变异及舒适度评价

由于预应力损失、混凝土收缩徐变、超载等原因,预应力混凝土桥梁出现了较强的振动。本文通过对福建省福州市闽江三桥全桥环境振动试验和正常运营条件下24小时的监测,研究预应力混凝土连续梁桥的动力特性及其变异和振动舒适度,结果表明:在较为稳定的风和温湿度环境下,固有频率在一天内的最大变化为3.06%,模态阻尼比的最大变化为37.93%,舒适度的狄克曼指标降到“能忍受短时间振动”的区域。     

实时子结构实验Chang算法的稳定性和精度

与慢速拟动力子结构实验相比,实时子结构实验的优点在于它能真实地反映速度相关型试件的特性。实时子结构实验的逐步积分算法通常借用拟动力算法,但是目前液压伺服作动器很难实现速度反馈控制,因而试件速度不能实现原算法的假定值,这样一来算法的稳定性和计算精度将发生改变。台湾学者S.Y.Chang提出一种无条件稳定的显式拟动力算法,本文分析了这种方法应用于实时子结构实验时的稳定性和计算精度。研究发现在实时子结构实验中该方法由无条件稳定变成了有条件稳定的,精度也发生了改变。     

Mechanical compression release device in steel bracing system for retrofitting RC frames

1 Introduction Braced steel frames are commonly used to resist seismic loads. Their seismic behavior was extensively studied during the past decades (Bertero et al.., 1989; Roeder, 1989; Jain, 1978). Their design is governed by the buckling behavior of the bracing members (ASCE, 1994,2002; CSA, 1994). To prevent or delay the seismic buckling of compressive members in concentrically braced frames in steel structures, a great number of methods have been proposed. These include the use of sp…     

半参数模型统计诊断与粗差检验(英文)

This paper systematically studies the statistical diagnosis and hypothesis testing for the semiparametric linear regression model according to the theories and methods of the statistical diagnosis and hypothesis testing for parametric regression model.Several diagnostic measures and the methods for gross error testing are derived.Especially,the global and local influence analysis of the gross error on the parameter X and the nonparameter s are discussed in detail;at the same time,the paper proves that the d...     

Coupled finite‐element simulation of injection well testing in unconsolidated oil sands reservoir

This paper presents a finite‐element (FE) model for simulating injection well testing in unconsolidated oil sands reservoir. In injection well testing, the bottom‐hole pressure (BHP) is monitored during the injection and shut‐in period. The flow characteristics of a reservoir can be determined from transient BHP data using conventional reservoir or well‐testing analysis. However, conventional reservoir or well‐testing analysis does not consider geomechanics coupling effects. This simplified assumption has limitations when applied to unconsolidated (uncemented) oil sands reservoirs because oil sands deform and dilate subjected to pressure variation. In addition, hydraulic fracturing may occur in unconsolidated oil sands when high water injection rate is used. This research is motivated in numerical modeling of injection well testing in unconsolidated oil sands reservoir considering the geomechanics coupling effects including hydraulic fracturing. To simulate the strong anisotropy in mechanical and hydraulic behaviour of unconsolidated oil sands induced by fluid injection in injection well testing, a nonlinear stress‐dependent poro‐elasto‐plastic constitutive model together with a strain‐induced anisotropic permeability model are formulated and implemented into a 3D FE simulator. The 3D FE model is used to history match the BHP response measured from an injection well in an oil sands reservoir. Copyright © 2013 John Wiley & Sons, Ltd.     

纵观近代岩矿测试分析技术

本文就近代岩矿测试分析技术作了较为全面的介绍。文章指出，地矿部从８０年代起，由于引进了大批现代先进仪器设备，使岩矿测试分析技术出现了崭新面貌，形成为多学科相结合的新格局，从而促进地质科学在理论上和实践上均取得显著进步，在某些学科领域已发生了根本性变化，并为地质或其它市场提供了大量信息，为促进科技成果转化为生产力作出了巨大贡献。纵观近代岩矿测试分析技术，文章提出了多机联用、整体分析和拓宽测试分析领域的建议，以更好地为祖国经济主战场服务。     

高精度锥体棱镜的“自差法”检测技术

本文提出一种采用“自差法”检测高精度锥体棱镜的新方法，阐述检测原理与装置，建立检测角度和面形误差的定量判据，并给出一个实例说明其应用。实践表明，“自差法”检测技术对于产品质量的控制，具有快速准确和简便实用等特点。     

转矩转速传感器及其在钻机功率测试中的应用

介绍了一种用于钻机功率测试的转矩转速传感器，论述了该类传感器的基本工作原理、标定装置、校验方法以及测试系统的组成等问题。     

An analysis of coal bump liability in a bump prone mine

Summary This paper presents an analysis of causes of bump in a deep coal mine. The analysis consists of in-mine measurement determination, analysis of physical and mechanical properties of mine materials and simulation of mine layout and mining sequence. Major factors contributing to the causes of bump have been reviewed and those that are related to this case have been identified and simulated analytically using a three-dimensional finite element method.     

Complex behaviour of a coal sample in a large scalein situ compression test

Summary A large scalein situ compression test of a laminated coal cube is described. The cube was uniformly loaded by a system of hydraulic jacks supplied simultaneously from one pump. At the same time both load and deformations were controlled. Deformations were measured by 60 longitudinal gauges located at the side surface of the cube in the regular net. Due to the heterogeneity of the rock the readings showed scatter. As a first approximation, the scattered data were fitted to the plane using the least square method. Orientations of the planes were analysed and show permanent relative movement between adjacent lamina indicating complex behaviour of the cube under loading. Detailed analysis of this behaviour indicated that the cube was subjected to both bending and twisting.