Preconditioned variational methods on rotated finite difference discretisation

Due to their rapid convergence properties, recent focus on iterative methods in the solution of linear system has seen a flourish on the use of gradient techniques which are primarily based on global minimisation of the residual vectors. In this paper, we conduct an experimental study to investigate the performance of several preconditioned gradient or variational techniques to solve a system arising from the so-called rotated (skewed) finite difference discretisation in the solution of elliptic partial differential equations (PDEs). The preconditioned iterative methods consist of variational accelerators, namely the steepest descent and conjugate gradient methods, applied to a special matrix ‘splitting’ preconditioned system. Several numerical results are presented and discussed.     

Convergence of a parallel jacobi-type method

A relaxed Jacobi-type iterative scheme is presented for solving linear algebraic systems. The method possesses a high level of parallelism and can be implemented on a multiprocessor system with or without synchronisation. The convergence region of the relaxation parameter is determined under the condition that the Jacobi iteration matrix possesses real eigenvalues. However, when the method is applied to consistently ordered systems, it is preferrable to let the parameter equal to unity and use Conjugate Gradient methods [3] to further increase the convergence rate.     

A Low‐Memory,Straightforward and Fast Bilateral Filter Through Subsampling in Spatial Domain

In this work we present a new algorithm for accelerating the colour bilateral filter based on a subsampling strategy working in the spatial domain. The base idea is to use a suitable subset of samples of the entire kernel in order to obtain a good estimation of the exact filter values. The main advantages of the proposed approach are that it has an excellent trade‐off between visual quality and speed‐up, a very low memory overhead is required and it is straightforward to implement on the GPU allowing real‐time filtering. We show different applications of the proposed filter, in particular efficient cross‐bilateral filtering, real‐time edge‐aware image editing and fast video denoising. We compare our method against the state of the art in terms of image quality, time performance and memory usage.     

A study of hand grip pressure distribution and EMG of finger flexor muscles under dynamic loads

A matrix of miniature and flexible pressure sensors is proposed to measure the grip pressure distribution (GPD) at the hand-handle interface of a vibrating handle. The GPD was acquired under static and dynamic loads for various levels of grip forces and magnitudes of vibration at different discrete frequencies in the 20–1000 Hz range. The EMG of finger flexor muscles was acquired using the silver-silver chloride surface electrodes under different static and dynamic loads. The measured data was analysed to study the influence of grip force, and magnitude and frequency characteristics of handle vibration on: (i) the local concentration of forces at the hand-handle interface; and (ii) the electrical activity of the finger flexor muscles. The results of the study revealed high interface pressure near the tips of index and middle fingers, and base of the thumb under static grip conditions. This concentration of high pressure shifted towards the middle of the fingers under dynamic loads, irrespective of the grip force, excitation frequency, and acceleration levels. The electrical activity of the finger flexor muscles increased considerably with the grip force under static as well as dynamic loads. The electrical activity under dynamic loads was observed to be 1·5–6·0 times higher than that under the static loads.     

对提高学术讲座质量和水平的几点思考

文章对如何提高学术讲座质量和水平进行了思考及研究，认为令人满意的学术讲座需要具备有一定理论深度和创新的中心观点，要有好的结构设置和逻辑结构，同时在讲座过程中要运用多种表现手段。     

恰希玛核电站二期工程核岛基坑降水与回灌技术

恰希玛核电站二期工程核岛基坑降水与回灌，没有可供参考的先例。本文阐述了降水与回灌所经历的过程、改进措施以及最后取得的成果，总结了与回灌技术相关的经验教训，为类似的大型工程提供借鉴。     

Analysis of singular stress fields at multi‐material corners under thermal loading

The scaled boundary finite‐element method is extended to the modelling of thermal stresses. The particular solution for the non‐homogeneous term caused by thermal loading is expressed as integrals in the radial direction, which are evaluated analytically for temperature changes varying as power functions of the radial coordinate. When applied to model a multi‐material corner, only the boundary of the problem domain is discretized. The boundary conditions on the straight material interfaces and the side‐faces forming the corner are satisfied analytically without discretization. The stress field is expressed semi‐analytically as a series solution. The stress distribution along the radial direction, including both the real and complex power singularity and the power‐logarithmic singularity, is represented analytically. The stress intensity factors are determined directly from their definitions in stresses. No knowledge on asymptotic expansions is required. Numerical examples are calculated to evaluate the accuracy of the scaled boundary finite‐element method. Copyright © 2005 John Wiley & Sons, Ltd.     

大容量快速开断装置

分析了传统的断路保护器在短路故障保护中的缺陷,介绍了大容量快速开关装置(简称FSR)的基本工作原理,以及FSR在多种保护线路中的联接方式和使用效果。     

关于连锁企业配送中心建设的思考

针对国内连锁企业配送中心的发展现状,提出诸如树立正确的配送中心观、政府引导、软件和硬件建设等方面的建议,以构建现代化的连锁企业配送中心,促进我国连锁企业的健康发展。     

浅谈新世纪分析化学发展的一些看法

从分析化学的研究对象、发展规律入手,展望新世纪分析化学更加辉煌的发展。