A new thermomechanical model of cutting applied to turning operations. Part I. Theory

In this paper, an analytical approach is used to model the thermomechanical process of chip formation in a turning operation. In order to study the effects of the cutting edge geometry, it is important to analyse its global and local effects such as the chip flow direction, the cutting forces and the temperature distribution at the rake face. To take into account the real cutting edge geometry, the engaged part in cutting of the rounded nose is decomposed into a set of cutting edge elements. Thus each elementary chip produced by a straight cutting edge element, is obtained from an oblique cutting process. The fact that the local chip flow is imposed by the global chip movement is accounted for by considering appropriate interactions between adjacent chip elements. Consequently, a modified version of the oblique cutting model of Moufki et al. [Int. J. Mech. Sci. 42 (2000) 1205; Int. J. Mach. Tools Manufact. 44 (9) (2004) 971] is developed and applied to each cutting edge element in order to obtain the cutting forces and the temperature distributions along the rake face. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening, the thermomechanical coupling and the inertia effects are taken into account in the modelling. The model can be used to predict the cutting forces, the global chip flow direction, the surface contact between chip and tool and the temperature distribution at the rake face which affects strongly the tool wear. Part II of this work consists in a parametric study where the effects of cutting conditions, cutting edge geometry, and friction at the tool–chip interface are investigated. The tendencies predicted by the model are also compared qualitatively with the experimental trends founded in the literature.     

装备绿色维修的发展方向

在以绿色为主题，以可持续发展和建设节约型社会为目标的历史时期，绿色维修已成为新的维修理念。装备绿色维修的内涵是节约资源、保护环境、提高效能、保证安全。国外以信息化为基础的装备绿色维修成为发展的主流。目前我国装备维修正朝着绿色方向发展，为实现装备的绿色维修本文提出了4点建议。     

武钢板带材生产技术与工艺装备的发展

全面分析介绍了武汉钢铁（集团）公司在板带材生产和工艺装备方面的发展、主要技术进步和所取得的成就，并提出武钢今后板带材生产技术研究的方向是实现高效、低耗、优质及清洁生产。     

基于压电晶体的高效电能转换设备设计

为了高效地利用风能和雨能，设计了通过压电传感器组件a将风或雨的能量转换为电能的装置。该装置可为负载和蓄电池供电，它的分辨力高，即使是弱风和小雨产生的微压也能进行电能转换。当压电晶体板d或e受压时，小齿轮顺时针或逆时针旋转；当压电晶体b或c受压时，液压缸伸长或收缩。在液压缸和小齿轮的作用下，压电晶体板a所在平面的法线自动调整到正好与风和雨的方向一致，从而增大了电能转化率。     

A new thermomechanical model of cutting applied to turning operations. Part II. Parametric study

In Part I of this work, Molinari and Moufki [Int. J. Mach. Tools Manufact., this issue], an analytical model of three-dimensional cutting is developed for turning processes. To analyse the influences of cutting edge geometry on the chip formation process, global effects such as the chip flow direction and the cutting forces, and local effects such as the temperature distribution and the surface contact at the rake face have been investigated. In order to accede to local parameters, the engaged part in cutting of the rounded nose is decomposed into a set of cutting edge elements. Thus each elementary chip, produced by a straight cutting edge element, is obtained from an oblique cutting process defined by the corresponding undeformed chip section and the local cutting angles. The present approach takes into account the fact that for each cutting edge element the local chip flow is imposed by the global chip movement. The material characteristics such as strain rate sensitivity, strain hardening and thermal softening, the thermomechanical coupling and the inertia effects are considered in the modelling. A detailed parametric study is provided in this paper in order to analyse the effects of cutting speed, depth of cut, feed, nose radius and cutting angles on cutting forces, global chip flow direction and temperature distribution at the rake face. The influence of friction at the tool–chip interface is also discussed.     

Gaze direction based vehicle teleoperation method with omnidirectional image stabilization and automatic body rotation control

In robot teleoperation, a robot works as a physical agent at a remote site for a robot operator. There are mainly two tasks in robot teleoperation using camera images: environment recognition using visual information and robot control according to the recognition. In this paper, we propose a gaze direction based vehicle teleoperation method with an omnidirectional image stabilization and an automatic body rotation control. In the proposed method, we manage above two tasks in the same manner that are usually treated separately. This method is an intuitive vehicle teleoperation method where an operator do not need to have concern about vehicle body orientations and can absorb differences of vehicle driving mechanisms. That is, this method frees an operator from being bothered from controlling a vehicle and the operator can concentrate on where he/she intends to go. This method mainly consists of two technologies: an omnidirectional image stabilization technology and automatic body rotation control. The conducted experiments show effectiveness of the proposed method.     

非开挖电力竣工管道铺缆回拖力测试仪

针对电力竣工管道铺设电缆时回拖力测试的需要,设计了一种铺缆回拖力测试仪,仪器由机械结构、数据处理电路及上位机软件组成。仪器随电缆从管道始端至终端拖行,期间将整个施工过程中的回拖力采集并存储起来,施工完毕后通过上位机软件将仪器内存储的数据读出,进行进一步的分析、处理及显示。仪器加工完成后进行了大量的室内外实验,实验结果显示：仪器符合实际施工测试要求。     

一种动态窗口PCA运动方向估计算法

首先针对个人航位推算系统中计步算法的阈值设定问题,提出了一种基于有限状态机的阈值自学习算法.通过该算法可以在较短的时间内(10s)获得自适应阈值,提高计步算法的准确性.然后在利用该阈值进行计步的同时,对连续步态进行分割,并以分割结果作为动态窗口进行主成分分析,可以获取目标运动的方向.此外,通过利用运动步态模型中加速度变化的规律可以有效解决180°模糊问题.实验分析结果表明,相比于固定窗口的 PCA 分析方法,基于动态窗口的 PCA 在数据处理量降低61.2%的情况下,其准确度提高了11.1%.     

基于变密度稀疏采样的微波辐射干涉测量反演成像方法

针对微波辐射干涉测量在频域中进行测量值具有低频信息较少、高频信息丰富,且低频信息和高频信息分布比较集中的特点,提出了一种基于变密度稀疏采样的微波辐射干涉测量方法.该方法将测量的频域信息进行分块,根据不同块所包含信息量的不同,利用变密度进行稀疏采样.考虑微波辐射图像本身具有的梯度稀疏性和局部光滑性特征,建立全变差正则化约束的成像模型,并采用交替迭代算法进行微波辐射图像最优重构.仿真和实验结果表明,结合变密度稀疏采样方法和交替迭代重构算法能够快速、准确地反演高分辨率微波辐射图像;在总采样率相同的情况下,该方法能够大幅度提高反演图像的分辨率,且对低采样率情况效果显著.     

一种基于目标圆的有向强栅栏构建算法

K-栅栏覆盖是有向传感器网络覆盖控制的研究热点之一。提出一种基于目标圆的分布式有向强栅栏构建方法（DBCTC）。首次构建了节点目标圆和能耗比2个模型。以节点感知区域内横坐标最大的点为圆心,以感知半径为半径的圆就是目标圆。节点的运动能耗和栅栏增益的比值就是能耗比。前一个节点根据目标圆模型选择后一个节点的最佳目标位置。从附近移动节点中选择能耗比最少的移动节点构建有向强栅栏。仿真结果证明,该栅栏构建方法比其他算法降低60%左右的能耗。