S7-400PLC在有色金属板带轧机控制系统中的应用

介绍由西门子ST-400PLC组成的有色金属板带轧机计算机控制系统.详述了自动化l级系统、自动化2级系统、通讯网络特点及控制系统的功能.     

面向高质量加工的NURBS曲线插补算法

通过分析数控系统加工时常用的插补算法的特点,提出一种基于NURBS曲线的插补算法.该算法包括速度规划和实时插补两部分:速度规划部分考虑了工件加工时允许的最大轮廓误差,以保证高速运行过程中加速度的连续,使机床运行平稳,避免产生大的冲击;实时插补部分应用弦截法计算插补参数,能将实时插补产生的速度波动控制到理想水平,进一步减小了机床震颤.仿真实验结果表明,文中算法能够减小机床振动,实现高质量加工.     

视觉P300脑机接口中的SOA扰动现象

异步操控性是脑机接口走向实际应用的关键技术之一.其关键点在于寻找一种可有效区分脑机接口工作状态和空闲状态的指标.建立了针对P300脑机接口的刺激起始异步(SOA)扰动模型,在仿真实验和实测数据中观察到SOA扰动谱线,并根据所提出的模型给出了合理解释.研究了SOA扰动的频域特性,结果表明,当SOA位于220 ms附近时,SOA扰动的强度最大,而当SOA低于150 ms时,SOA扰动强度将急剧减小.同时SOA扰动所具有的锁相性使得可以通过时域相干平均法进一步提高信噪比.SOA扰动可作为脑机接口处于工作状态的标志,为异步脑机接口的实现提供了一种新的研究思路.     

多变量分支混沌签名体制

针对量子计算机对现有密码算法的威胁,结合多变量公钥体制和混沌系统,提出一种能抵抗量子算法的分支密码体制。体制的中心映射有两个分支,分支一使用传统多变量公钥密码体制,分支二使用混沌密码体制,将两分支的输出结果相加,最后通过仿射变换将中心映射进行隐藏。利用分支结构提高计算效率,利用混沌系统克服传统多变量公钥密码体制的缺点以增强安全性,适用于各类设备进行签名运算。     

针对发音质量评测的声学模型优化算法

在发音质量评测研究中,传统仅用发音标准的数据进行声学建模,难以描述实际测试面临的非标准发音,使得训练与测试的失配在所难免。针对上述问题,该文提出一种利用覆盖各种发音的数据,根据最小化机器分与人工分均方误差准则进行声学模型优化的算法。实验在普通话水平考试现场3 685份数据(其中498份测试,3 187份训练)上进行。实验表明采用优化算法得到的针对发音质量的评测声学模型相比传统建模方式得到的声学模型有显著的优势。     

基于遗传算法的数值优化约束问题的研究

针对数值优化约束中出现的大规模、多峰多态函数,含离散变量等情况下的全局优化问题,采用常规的优化方法,收敛速度较慢,求得全局极值的概率较低.提出用遗传算法的数值优化约束问题解决,通过数值仿真实验结果表明,该算法性能优于现有其它算法,它不仅可以处理线性等式约束,而且还可以处理非线性等式约束,同时提高了收敛速度和解的精度,是高效稳健的智能算法,具有很高的全局寻优能力和很快的收敛速度,对求解复杂多峰多态函数的优化约束问题具有可行性和有效性.     

计算机网络工程全面信息化管理探索

随着世界现代文明的发展和技术的日新月异,计算机网络信息管理技术在提高企业及政府部门办事效率的应用方面,表现出越发重要且不可替代的作用。通过简单介绍计算机网络工程全面信息化管理的相关概念及其重要性和现实意义,深度剖析计算机网络工程全面信息化管理在当前社会应用中的优势与困难,并提出对策和相关建议。     

计算机监控系统在张河湾水电站的应用

论述了张河湾水电站计算机监控系统的结构配置和功能特点。该系统实现了对张河湾水电站生产过程的实时监测、控制、保护、调节、数据采集,以及运行参数自动记录等功能,实现了电站＂无人值班＂或＂少人值守＂的运行管理模式。     

Practice and carryover effects when using small interaction devices

The use of interaction devices in modern work often challenges the human motor system, especially when these devices introduce unfamiliar transformations to the user. In this paper we evaluated expert performance and skill differences between experts and novices when using small motion- and force-controlled interaction devices (touchpad and mini-joystick) in an applied text-editing task. Firstly, experts performed better with their familiar input device than with an unfamiliar one. Particularly touchpad experts operating the unfamiliar mini-joystick showed highly asymmetric carryover costs. Results showed that the efficient performance of experts depended on domain-specific skills, which were not transferable. Secondly, with considerable practice (more than observed for simple and short tasks) novices were brought up to higher levels of performance. The motion-transformation between hand and cursor action was easier in understanding and application than the force-transformation. Thus, the touchpad was used more efficiently than the mini-joystick. In conclusion, practice effects found so far are considerably underestimated when it comes to an applied task. The results give reason to develop and implement skill-sensitive training procedures, since the acquisition of domain-specific skills is critical for expert performance. As a consequence, training procedures might be essential for complex applications and/or unfamiliar device transformations.     

Light scattering from anisotropic, randomly rough, perfectly conducting surfaces

An approach is introduced for performing rigorous numerical simulations of electromagnetic wave scattering from randomly rough, perfectly conducting surfaces. It is based on a surface integral technique, and consists of determining the unknown electric surface current densities from which the electromagnetic field everywhere can be determined. The method is used to study the scattering of a p-polarized beam from an anisotropic Gaussian, randomly rough, perfectly conducting surface. It is demonstrated that the surface anisotropy gives rise to interesting and pronounced signatures in the angular intensity distribution of the scattered light. The origins of these features are discussed.