一沉池变截面池壁有限元分析

详细介绍了运用SAP2000进行有限元分析一沉池变截面池壁过程。通过对计算结果进行分析比较,最后总结变截面池壁内力变化规律。本文的计算分析方法和结论可供设计人员参考。     

DASP技术在现代测试仪器平台中的应用

本文将先进的DASP（Data Alias-free Signal Processing）抗混叠信号采样技术运用到现代测试仪器平台中。通过恰当地选取采样点位置和改进信号处理算法,解决了信号采样中以较少点重构高频信号的问题,该技术抗混叠和消除混叠频谱噪声的特点允许它能准确检测到各个不同幅度的信号。研究表明：DASP技术融入测试平台能以较低的采样率有效地提取高频信号,提高了测试精度和效率。     

变截面梁的应力计算及其分布规律研究

为了合理计算预应力混凝土变截面箱形梁的剪应力,客观反映其应力分布状况,首先推导了任意变截面梁剪应力计算的一般公式,在此基础上,考虑箱形梁的梁高、底板厚度、腹板厚度沿跨度的变化,导出了变截面箱形梁的剪应力实用计算公式。应用导出的公式,结合矩形及箱形变截面悬臂梁算例,分析了变截面梁的应力分布状况。研究结果表明,变截面梁横截面上的最大剪应力并不发生在截面重心轴处,而是在重心轴以下区域或梁底缘处;变截面箱形梁的底板受有很大剪应力作用,为了合理设计变截面箱形梁,不应采用薄底板,而且应加强其配筋及构造处理。     

Exact closed form solutions for free vibration of non-uniform annular plates

Presented herein are exact solutions for the free vibration problems of a class of annular plates with parabolically varying rigidity and for a sandwiched non-uniform annular plate. These exact solutions are useful for verifying numerical methods and algorithms.     

Series/Parallel Time-Multiplexed Switched-Capacitor Filters with Programmability Based on Non-Uniform Sampling

This paper presents an improved scheme for programmable time-multiplexed (TM) switched-capacitor (SC) filters. The proposed approach uses a novel sampling technique, which eliminates the need for resolution/area tradeoffs. The programmability of each processing channel is based on the use of non-uniform clock signals with noise-shaped sampling energy. No capacitor values are modified for programming frequency response parameters and, hence, the performance of the TM SC filter is not sacrificed for programmability. Such a sampling technique not only leads to an accurate frequency response control, but also allows the design procedures and the resulting SC circuit implementation to be simplified. A test-chip including a programmable second-order TM SC filter with a multiplexing order of four, which operates in series or in parallel mode, was fabricated in conventional CMOS technology. Measurement results demonstrate the effectiveness and versatility of the proposed technique.     

Reconstruction of Piecewise Smooth Functions from Non-uniform Grid Point Data

Spectral series expansions of piecewise smooth functions are known to yield poor results, with spurious oscillations forming near the jump discontinuities and reduced convergence throughout the interval of approximation. The spectral reprojection method, most notably the Gegenbauer reconstruction method, can restore exponential convergence to piecewise smooth function approximations from their (pseudo-)spectral coefficients. Difficulties may arise due to numerical robustness and ill-conditioning of the reprojection basis polynomials, however. This paper considers non-classical orthogonal polynomials as reprojection bases for a general order (finite or spectral) reconstruction of piecewise smooth functions. Furthermore, when the given data are discrete grid point values, the reprojection polynomials are constructed to be orthogonal in the discrete sense, rather than by the usual continuous inner product. No calculation of optimal quadrature points is therefore needed. This adaptation suggests a method to approximate piecewise smooth functions from discrete non-uniform data, and results in a one-dimensional approximation that is accurate and numerically robust.      

矩形非均匀采样算法和对数级坐标变换算法的比较分析

针对对数极坐标变换引起的图像周边模糊和图像细节丢失等现象，提出了矩形非均匀采样方法。图像中心采样区的大小可根据实际需要进行选取，对其进行均匀采样，对周边区进行分层均匀采样，随距采样中心距离的增大，采样率逐渐降低。对矩形非均匀采样、经典LPT和变参数LPT三者的运算量进行了比较，总体上说，矩形方法具有最少的运算量，而且可以克服对数极坐标变换图像的扭曲，并便于硬件实现。     

基于MATLAB的非均匀悬移质不平衡输沙计算

针对一维非均匀悬移质不平衡输沙数学模型中的明显淤积过程,应用MATLAB语言编制了计算程序,并采用泾惠渠实测水沙资料进行了算例演示。结果表明:程序计算值与实测值符合较好,模型能够满足实际工程要求。     

大型电厂的输煤栈桥可靠度分析

本文利用多点非一致激励反应普分析理论分析研究了在不同烈度下的输煤栈桥的抗震可靠度。利用响应港分析方法,假定地震过程为平稳随机过程,考虑行波效应及部分相干效应,选择合适的可靠性震害参数,按照结构可靠度分析理论的要求,计算出了结构在不同地震烈度下的失效概率,并给出了震害预测结果及建议。     

铁摩辛柯梁弯曲问题的精细积分法

Timoshenko梁弯曲问题的哈密顿对偶方程,是关于梁截面上的广义力和广义位移的一阶常微分方程组,可与现代控制理论的一些问题相比拟。由于系统矩阵具有辛矩阵的特性,数值计算具有良好的稳定性,可将Timoshenko梁弯曲问题的两端边值问题转化成初值问题,用精细积分法求得高精度的数值解。算例计算结果表明,本方法具有较高的精度和适用性,并可方便地用于变截面梁的计算。