双螺杆转速差决定的螺杆间隙之探讨

根据相对运动原理计算了同向旋转双螺杆因螺杆转速差决定的两螺杆之间的径向和轴向间隙,可为工程上设计这些间隙时提供参考。     

高速工具钢电化学抛光

讨论了高速工具钢（W9Mo3Cr4V）电抛光，分别研究了电流密度、抛光时间和抛光温度与粗糙度之间的关系，并应用正交实验找出了一组适舍高速工具钢电抛光的最佳工艺奈件。     

基于FPGA的高速数据转存系统

SAR雷达前端数据采集系统速度与存储系统容量的日益提高,对数据转存系统的性能提出了更高的要求以Xilinx公司Virtex-5系列FPGA为硬件平台,基于PCI—E协议与Aurora协议提出了一种高速数据转存系统解决方案．在Aurora协议基础之上,自定义了一种可靠的帧格式;利用双口RAM对数据进行缓存,以乒乓方式操作,确保了在输入、输出数据传输速率不匹配情况下数据传输的稳定性与可靠性：转存系统与PC通过PCI-E总线进行通信,命令交互采用PIO模式,图像与列表数据传输采用DMA模式．经实际测试,该方案能够满足某型号SAR雷达系统对高速数据转存的要求．     

数字式电子调速器的研究

简述了电子调速器的产生和发展、优点以及应用的领域,电子调速器的四个组成部分：控制器、执行器、执行器驱动机构和传感器,各个组成部分的作用,不同调速系统采用的不同的执行器和传感器;分述了不同的控制策略：PID控制、模糊控制、模糊PID控制和模糊自适应PID控制,以及对调速系统的调速性能和稳定性的提高;不同系统采用的不同的建模和仿真方法,提出了现阶段电子调速技术存在的几个问题：控制算法的选择、控制器的处理能力和执行器的精度;今后发展的方向：引入智能控制算法、多CPU结构体系的采用、控制器的抗干扰以及专用执行器和传感器的开发和扩展更广阔的应用领域.     

铁芯片数控横剪生产线中的速度同步控制

横剪线是变压器铁芯硅钢片生产的专用设备,可将一定宽度的硅钢卷料按照操作者预先编制的程序剪切成各种形状硅钢片料.由于整条生产线上的送料轨道较长,为了保证剪切精度,使硅钢片在导轨中能够高速平稳的传送,就需要在送料导轨上安装一台拉料电机.本文主要介绍如何使拉料电机与送料电机实现速度的匹配.     

LTE小区搜索中一种新的SSS检测算法

主要研究了SSS检测, 提出一种新的SSS检测算法。该算法首先利用滑动平均窗修正接收的PSS处估计出的信道频率响应, 并用修正后的信道频率响应对接收的SSS序列进行信道补偿; 其次, 算法对信道补偿后的序列进行实数提取操作, 消除虚部数据干扰; 最后算法联合两个连续的SSS接收序列进行检测进一步提高检测性能。TDD和FFD两种模式下的仿真结果表明：该算法可以较好地实现SSS检测且比现有几种SSS检测算法在低信噪比（SNR<0 dB）条件下具有更好的检测性能。     

Effects of carbon black on tribology of blends of poly(vinylidene fluoride) with irradiated and non-irradiated ultrahigh molecular weight polyethylene

Friction and wear resistance are two vital tribological properties of polymer-based materials but optimization of both is rarely attempted. We have investigated blends of 70 wt% poly(vinylidene fluoride) (PVDF)+30% ultra high molecular weight polyethylene, the latter either un-irradiated or else γ-irradiated. Each sample contained varying amounts of carbon black (CB) and also had a varied degree of crosslinking and irradiation dose. We have determined static and dynamic friction, scratch resistance, and sliding wear in multiple scratching tests. Effects of the irradiation dose and CB concentration have been quantified. The electric conductivity threshold is reflected in a drop of static friction; formation of a continuous phase of the lubricant affects tribology as well as electrical properties—both for irradiated and for un-irradiated samples. The scratch resistance as represented by the residual (healing) depth is affected by crosslinking, by the stage at which irradiation is applied (before or after blending) and by CB addition. Crosslinking by moderate amounts of irradiation provides shallower residual depths while higher doses cause adverse results. Similarly, the CB lubricant can either improve or worsen the scratch resistance. A combination of both approaches produces either better or else worse results than crosslinking alone. Lower friction seems accompanied by higher scratch resistance. A combination of a specific irradiation dose and an optimized CB concentration lowers the sliding wear significantly. Strain hardening in sliding wear determination takes place for all materials studied, irrespective of the extent or radiation-induced crosslinking and of the presence and concentration of carbon black.     

On adaptive sliding mode control without switching gain overestimation

This paper presents some further results on adaptive sliding mode control (ASMC) for a class of nonlinear systems with bounded uncertain parameters. Given a large initial tracking error, current ASMC design generally produces an unnecessarily large switching gain, consequently leading to a serious chattering problem or a large‐amplitude control jump for the continuous counterpart. To solve such an overadaptation problem, the switching gain adaptation mechanism is first analyzed in this paper, and the adaptation induced by the initial tracking error is suggested to be removed. Then, by exploiting the global sliding mode feature of time‐varying sliding mode control and integral sliding mode control, we present two effective methodologies for ASMC design. The proposed ASMC algorithms ensure that there is no overestimation of the switching gain and the system response is not slowed down when a small switching gain is generated. The validity of the proposed methods is verified by both theoretical analysis and simulation results. Copyright © 2012 John Wiley & Sons, Ltd.     

卧螺离心机共直流母线双电机双变频驱动

介绍了卧螺离心机差转速自动控制共直流母线变频调速系统的结构,分析了工作原理和节能效果,介绍了直流母线的两种并接方法。