An extended basis inexact shift–invert Lanczos for the efficient solution of large-scale generalized eigenproblems

This paper proposes a technique, based on the Inexact Shift–Invert Lanczos (ISIL) method with Inexact Jacobi Orthogonal Component Correction (IJOCC) refinement, and a preconditioned conjugate-gradient (PCG) linear solver with multilevel preconditioner, for finding several eigenvalues for generalized symmetric eigenproblems. Several eigenvalues are found by constructing (with the ISIL process) an extended projection basis. Presented results of numerical experiments confirm the technique can be effectively applied to challenging, large-scale problems characterized by very dense spectra, such as resonant cavities with spatial dimensions which are large with respect to wavelengths of the resonating electromagnetic fields. It is also shown that the proposed scheme based on inexact linear solves delivers superior performance, as compared to methods which rely on exact linear solves, indicating tremendous potential of the ‘inexact solve’ concept. Finally, the scheme which generates an extended projection basis is found to provide a cost-efficient alternative to classical deflation schemes when several eigenvalues are computed.     

带式输送机垂直曲线段的优化设计

简要介绍了带式输送机的应用领域及带式输送机垂直曲线段的作用,重点对垂直凹弧段的主要参数、凹弧段半径的校核、胶带张力与凹弧曲线段半径的关系进行阐述,为合理地选用带式输送机提供了理论基础。     

输水隧洞施工盾构管片修补措施

总结了输水隧洞盾构施工过程中盾构管片存在的主要缺陷，从材料选择和修补技术方面，阐述盾构管片修补措施。研究成果可为类似工程施工提供参考。     

斜角切削切削刀具流屑平面内应力分布的实验研究(Ⅱ)

实验在经改装后的铣床上进行,以聚碳酸酯作为刀具模型材料切削铅板。由作者专门设计的切削装置与小型光弹性仪联为一体,可方便地安装在铣床上跟踪、观察和拍摄切削的全过程,对切削中受力的模型进行冻结、切片。在光弹性仪中描绘等倾线、等差线,最后应用应力分离法获得斜角切削中流屑平面内刀具前刀面上的应力分布。     

关于“逆算单元长度法”的改进

本文对原有的“逆算单元长度法”进行了适当的改进,并编制了相应的计算程序.计算表明:改进后的逆算单元长度法计算效率明显提高.同时,本文计算所得的等端弯矩作用下工字形截面和双角钢T形截面的N/N_P-M/M_P相关曲线可供设计参考,具有一定的实用价值.     

一种适宜插补的三次样条拟合方式

本文从插补和工程应用的角度出发,提出了一种实用的三次样条拟合方式。这种拟合方式较好地解决了三次样条拟合大挠度曲线出现多余拐点的问题,有着计算简单的特点。用此种拟合方式拟合了若干实例,并绘图验证了该方法。     

光弹塑性冻结切片法在金属切削研究中的应用

以具有双折射性能的聚碳酸酯作为模型材料,进行自由斜角切削。采用光弹塑性的冻结切片法,对模型切削受力后的应力干涉条纹进行冻结,然后沿流屑剖面进行切片。为进一步研究斜角切削流屑剖面内的应力分布提供直观性强的干涉条纹图案。     

Applying the Hough transform pseudo-linearity property to improve computing speed

This work describes a general method of acceleration of the convergence of the Hough transform based, on the one hand, on an improvement of the image analysis speed, and, on the other hand, on the space undersampling of the image. This method is used in image processing to extract lines, circles, ellipses or arbitrary shapes. The results presented are applied to the detection of straight-line segments and ellipses, but can be extended to any type of transform.     

符合国家标准的工程图中相交点画线算法

国家标准中,图形中心线的线型是细点画线,两条点画线相交,应是线段交接,为此提出一种算法,该算法为:任意地输入两相交点画线4个端点的坐标,根据设定的原则,计算出点画线的线段长度,绘制2条交接在线段处的点画线。该算法用于计算机绘工程图,使绘制出的工程图符合国家标准[1]。     

基于Bark小波变换参数的语音寂声/语声段检测

提出了一种基于Bark小波变换参数的语音寂声/语声段检测方法。利用Bark小波的频率分级和能量聚焦能力,提取语音信号在不同子带上的统计参数;引入基于模糊熵的参数有效性分析,获得所有子带参数中分辨能力和稳定性最大的参数作为识别参数。仿真试验证明,该方法在不同噪声条件下稳定有效;比照传统参数,该方法在准确率和鲁棒性上都有较大幅度的提升。