Parallel Implementation of a Low Order Algorithm for Dynamics of Multibody Systems on a Distributed Memory Computing System

In this paper, a new hybrid parallelisable low order algorithm, developed by the authors for multibody dynamics analysis, is implemented numerically on a distributed memory parallel computing system. The presented implementation can currently accommodate the general spatial motion of chain systems, but key issues for its extension to general tree and closed loop systems are discussed. Explicit algebraic constraints are used to increase coarse grain parallelism, and to study the influence of the dimension of system constraint load equations on the computational efficiency of the algorithm for real parallel implementation using the Message Passing Interface (MPI). The equation formulation parallelism and linear system solution strategies which are used to reduce communication overhead are addressed. Numerical results indicate that the algorithm is scalable, that significant speed-up can be obtained, and that a quasi-logarithmic relation exists between time needed for a function call and numbers of processors used. This result agrees well with theoretical performance predictions. Numerical comparisons with results obtained from independently developed analysis codes have validated the correctness of the new hybrid parallelisable low order algorithm, and demonstrated certain computational advantages.     

New driving scheme for intelligent power‐efficient high‐voltage display drivers

Abstract— A new bistable‐display driver is presented. The innovation in the developed driver is the addition of a new logical block that calculates the most energy‐efficient driving waveforms. In this paper, the algorithms being applied to the row and column waveforms in order to reduce the power consumption are discussed. Some theoretical as well as experimental results are shown, proving a reduction in the power consumption by about 50%. The proposed algorithms are especially important for battery‐powered applications.     

Three-dimensional spinal motion and risk of low back injury during sheep shearing

Sheep shearers are known to work in sustained flexed postures and have a high prevalence of low back pain (LBP). As sustained posture and spinal movement asymmetry under substantial loads are known risk factors for back injury our aim was to describe the 3D spinal movement of shearers while working. We hypothesised that thoraco-lumbar and lumbo-sacral movement would be tri-axial, asymmetric, and task specific. Sufficient retro-reflective markers were placed on the trunk of 12 shearers to define thoraco-lumbar and lumbo-sacral 3D motion during three tasks. Thoraco-lumbar movement consistently involved flexion, left lateral flexion, and right rotation. Lumbo-sacral movement consistently involved right lateral flexion in flexion with minimal rotation. Shearers therefore work in sustained spinal flexion where concurrent, asymmetric spinal movements into both lateral flexion and rotation occur. These asymmetric movements combined with repetitive loading may be risk factors leading to the high incidence of LBP in this occupational group.     

一种基于区间约束的折半查找算法

针对变化范围很大而又相对稳定的查找对象,给出一种基于区间约束的折半查找算法。当后一个查找对象在前一个查找对象附近时,在最坏状态和平均状态下,该算法与标准的折半查找算法比较,其查找长度元旦显著减少,而且代价很小。此算法适合用于类似过程控制中的对低频信号的实时查有处理,并在国家级新产品WPJ－3微机频率事故记录装置和WQP－4微机频率继电器中得到了成功的应用。     

湿敏电阻器本体电阻对线性度的影响

通过理论推导 ,获知了湿敏电阻器的感湿特性曲线与拟合直线之间的偏差随其本体电阻的变化关系。由此可知 ,当感湿特性曲线位于电阻 -湿度平面上某个确定的区域内时 ,可通过增加本体电阻以改善线性度 ;而位于该区域外时 ,应减小本体电阻。     

高分子电容式湿度变送器温度补偿方法

提出一种新的高分子电容式湿度变送器温度补偿方法。实验结果表明 ,利用温度特性各异的高分子电容式湿敏元件互补进行温度补偿 ,可有效地减少温度系数和非线性误差、提高高分子电容式湿度变送器的准确度     

A low-power wireless video sensor node for distributed object detection

In this paper we propose MicrelEye, a wireless video node for cooperative distributed video processing applications that involve image classification. The node is equipped with a low-cost VGA CMOS image sensor, a reconfigurable processing engine (FPGA, Microcontroller, SRAM) and a Bluetooth 100-m transceiver. It has a size of few cubic centimeters and its typical power consumption is approximately ten times less than that of typical commercial DSP-based solutions. As regards classification, a highly optimized hardware-oriented support vector machine-like (SVM-like) algorithm called ERSVM is proposed and implemented. We describe our hardware and software architecture, its performance and power characteristics. The case study considered in this paper is people detection. The obtained results suggest that the present technology allows for the design of simple intelligent video nodes capable of performing classification tasks locally.

一种低比特率下的快速SAR图像压缩方法*

提出了一种低比特率的快速压缩方法,通过基于小波的降采样增强像素间的相关,继而使用小波包分解降采样后的图像并使用基于零块的方法对系数进行编码。实验结果表明用该方法进行压缩能够得到优于JPEG2000的主观效果,对边缘保持更好,并且计算量小,适合实时实现。     

石墨粒度对低炭镁炭砖性能的影响

以电熔镁砂和4种粒度(≤0.149mm、 ≤0.074mm、≤0.044mm和≤0.01mm)的天然鳞片 石墨为主原料,在石墨含量为4%的条件下,研究了 石墨粒度对低炭镁炭砖的物理性能、抗氧化性和热震 稳定性的影响。结果表明:用细石墨取代较粗石墨 (粒度≤0.149mm)制成的镁炭砖,其物理性能、抗氧 化性和热震稳定性都有了明显的改善,且都以加入粒 度≤0.074mm石墨的效果最好。其原因是细石墨的 加入改善了镁炭砖的基质结构。石　墨     

湿度扩散诱发的节理岩体时效变形特性研究

湿度对岩体结构性能的影响显著,不仅造成岩体物理力学性能弱化,还在一定程度上产生湿涨变形,进而改变岩体的应力状态,大大增强岩体的时效变形特性。为了分析节理岩体在高湿度环境下的时效变形,采用湿度-应力-损伤耦合数值模型对水敏感岩体隧洞开挖后的变形量、围岩内的湿度扩散,以及应力演化进行了数值分析。通过对单组和2组节理岩体的变形、应力、湿度扩散的分析,揭示了节理弱面对湿度扩散和岩体变形的强化作用。开挖隧洞拱顶和底板变形量的分析结果表明高湿度环境是水敏感岩体隧洞产生底鼓的重要原因之一。湿度扩散引起隧洞顶部和底部围岩产生大量破坏,致使相应部位的位移量陡增。此外,单组节理对岩体的湿度扩散的方向起到明显的导向作用,而多组相互斜交的节理则在一定程度上削弱了湿度扩散的各向异性。