基于VHDL的数字密码锁设计

本文主要介绍运用VHDL技术设计数字密码锁的方法。本设计采用自顶向下的数字系统设计方法,将数字密码锁系统分解为若干子系统,并且进一步细划为若干模块,然后用硬件描述语言VHDL来设计这些模块,并且分别进行软件和硬件的仿真。仿真结果表明:该数字密码锁能够校验3位十进制数密码,且可以预置密码,显示输入密码,具有输入错误指示,解码有效指示等相应的状态指示。该密码锁体积小,功耗低,操作简单,不怕掉电,维护和升级都十分方便,具有较好的应用前景。     

VHDL语言在现代数字系统中的应用

介绍了VHDL硬件描述语言在一个简单数字系统设计中的具体应用过程，论述了VHDL语言在基本结构和基本特征以及在现代数字系统中的重要地位和作用。     

用VHDL实现虚拟数字集成电路的故障检测

介绍以AlteraCPLD系列FLEX10K器件为虚拟载体,在Windows95／98下借助Delphi5．0实现人机交互界面,借助PC机的控制离线完成对常用TTL74和54系列、CMOS4000和4500系列、常用RAM、EPROM、部分CPU接口芯征的故障检测的VHDL设计原理和实现方法。     

Modeling and design of networked control systems using a stochastic switching systems approach

A networked control system (NCS) is a control system in which plants, sensors, controllers, and actuators are connected through communication networks. In this paper, we consider NCSs modeled by stochastic switching systems, and propose a new method for modeling and optimal control. First, a recursive representation of the expected value of the state is proposed. Next, after an over‐approximation of this recursive representation is derived, the optimal control problem is reduced to a linear programming problem. Finally, the effectiveness of the proposed method is shown by a numerical example. The proposed method provides us an easy‐to‐use control method for NCSs. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Fault tolerant digital systems

Two common dependability measures of fault-tolerant systems, availability and reliability, are defined, and the design of a reliable system is described. The first step is the incoming inspection of components to remove weak or defective components prior to assembly into subsystems. The next step is to use fault-avoidance techniques. Examples are careful signal routing, shielding, cabinet grounding, and inline static filters to increase the signal-to-noise ratio, limiting the fanout of gates to a small number to reduce the dissipation of power, and minimization of human errors through such measures as labeling and documentation. Another technique for increasing reliability is the use of a fault-tolerant design. Three approaches are examined: (1) fault-detection techniques (duplication, coding techniques, the check sum method, watchdog timers and timeouts, and consistency and capability checking); (2) fault-masking techniques (triple modular redundancy and error-correcting codes); (3) dynamic redundancy techniques. System diagnosis and the application of fault-tolerant systems are also discussed     

Efficient and realistic statistical worst case delay computation using VHDL

A method for worst case path-delay estimation in complex digital circuits is presented. It has been named Statistical Static Timing Analysis Using a Standard Logic Simulator (SSTA for SLog). It enables acceleration of algorithmically simple but computationally expensive and time-consuming Monte-Carlo simulations. The technique deals with fabrication-dependent delay variations of a particular technology. It applies a realistic rise/fall delay model with fanout dependent delays based on technology and implementation data.     

Modeling real-time balancing power demands in wind power systems using stochastic differential equations

The inclusion of wind power into power systems has a significant impact on the demand for real-time balancing power due to the stochastic nature of wind power production. The overall aim of this paper is to present probabilistic models of the impact of large-scale integration of wind power on the continuous demand in MW for real-time balancing power. This is important not only for system operators, but also for producers and consumers since they in most systems through various market solutions provide balancing power.     

Utility experience with digital excitation systems

Ontario Hydro, a Canadian utility with an installed capacity of over 30000 MW, has utilized static excitation systems on a large number of generators, ranging from 3 MVA to 1100 MVA in size, since the early 1960's. Ontario Hydro has always attempted to take advantage of excitation system control as a means of eliminating or reducing stability constraints on their operation. The advent of digital excitation systems offered us the opportunity to work with manufacturers to incorporate special features or controls which had previously required complex additional hardware. This paper discusses the authors' experience with these systems, from 1988 to date, as well as providing a list of items which merit consideration by utilities and manufacturers as they move toward the second generation of digitally-implemented systems     

Real-time digital simulation of power electronics systems with Neutral Point Piloted multilevel inverter using FPGA

Most of actual real time simulation platforms have practically about ten microseconds as minimum calculation time step, mainly due to computation limits such as processing speed, architecture adequacy and modeling complexities. Therefore, simulation of fast switching converters’ instantaneous models requires smaller computing time step. The approach presented in this paper proposes an answer to such limited modeling accuracies and computational bandwidth of the currently available digital simulators.As an example, the authors present a low cost, flexible and high performance FPGA-based real-time digital simulator for a complete complex power system with Neutral Point Piloted (NPP) three-level inverter. The proposed real-time simulator can model accurately and efficiently the complete power system, reducing costs, physical space and avoiding any damage to the actual equipment in the case of any dysfunction of the digital controller prototype. The converter model is computed at a small fixed time step as low as 100 ns. Such a computation time step allows high precision account of the gating signals and thus avoids averaging methods and event compensations. Moreover, a novel high performance model of the NPP three-level inverter has also been proposed for FPGA implementation. The proposed FPGA-based simulator models the environment of the NPP converter: the dc link, the RLE load and the digital controller and gating signals. FPGA-based real time simulation results are presented and compared with offline results obtained using PLECS software. They validate the efficiency and accuracy of the modeling for the proposed high performance FPGA-based real-time simulation approach. This paper also introduces new potential FPGA-based applications such as low cost real time simulator for power systems by developing a library of flexible and portable models for power converters, electrical machines and drives.     

数字系统结构性可测性设计

在高科技领域对数字系统工作的可靠性要求越来越高,因此数字系统的可测试性变得极为重要.要提高数字系统的可测性,解决这一问题的有效办法是从数字系统设计上着手,目前较好的办法是采用结构性可测性设计,而结构性可测性设计中电平灵敏扫描设计法使用较为普遍,也很实用.本文就电平灵敏扫描设计法进行探索.     

Hardware-software complex for testing digital control systems

In this issue a complex for the development and testing digital control systems based on real-time modeling is described. The inclusion of this complex into the production process allows for R&;D, testing, and debugging costs.     

Modeling of electrostatic-based pesticide spray systems

A microscopic model for the electrostatic spraying system is presented to investigate the effect of the voltage applied to the induction nozzle on the droplet's charge, mobility, and charge-to-mass ratio. The variation of these parameters along the jet was also included. The model also lays particular emphasis on the effect of the applied voltage on the spray current and the charge density at the nozzle. A macroscopic model for the electrostatic spraying system is also presented. The objective of the model was to study the spatial distribution of the droplet charge density, transit time, and trajectory in the region between the nozzle and the target in terms of the flow velocity of the spray and the space-charge-produced electric field. On the macroscopic scale, both the droplet charge density and the spray current increase with the voltage applied to the charging electrode. With the decrease of the spray flow velocity, the space-charge-produced electric field becomes dominant and tends to: contract the droplet trajectories toward the axis of the spray system, and hence enhance the droplet deposition efficiency; and decrease the charge density at the target with the possibility of minimizing back-ionization. On the microscopic scale, induction charging eliminates the ion current from the current to the target and the associated back-ionization. The calculated droplet charge and charge-to-mass ratio which increase with the voltage applied to the charging electrode, agreed with the values reported previously     

非线性系统的模糊输入多采样率数字控制

针对非线性系统的模糊多采样率数字控制问题,基于T-s模糊模型和离散模糊基函数值,建立了被控对象的输入多采样率数字控制系统模型.采用PDC控制原理,提出了一种新的模糊多采样率数字控制方法,给出了控制器设计算法,并通过求解带有线性矩阵不等式(LMI)约束的凸优化问题来获得控制器的参数.倒立摆控制器设计实例证明了设计方法是有效、可行的.     

数字化变电站自动化系统中以太网交换机的选择

以太网交换机是数字化变电站自动化系统中的关键性部件,它的性能和可靠性直接影响到变电站自动化系统的功能,但在实际的变电站自动化工程中,对以太网交换机的选用却往往重视不够。该文提出了在变电站自动化系统中的以太网交换机与继电保护设备是同等重要的观点,并从抗电磁干扰、环境温度、实时性和可靠性等方面分析了对在变电站自动化系统中使用的以太网交换机的要求,提出了对以太网交换机的选择建议,期望能够引起变电站自动化系统工程人员的重视,从而提高变电站自动化系统的可靠性。     

A modified sensitivity measure for linear digital systems

In this paper a new sensitivity measure for state space systems is proposed. This new measure is a modified form of Tavsanoglu and Thiele's measure but has three advantages: (1) it is more precise than Tavsanoglu and Thiele's measure when the parameters of the state space realizations contain 0 and ±1; (2) it can be used to explain why the sparse Schur and Hessenberg realizations can give better actual sensitivity performance than the corresponding fully parametrized optimal realizations; (3) it is identical with the global round-off noise gain G = tr(QW) + y obtained by Hwang under a dynamic constraint.     

Teaching digital systems in the South Africa context

This paper describes the structure of digital and computer system curricula at a university in South Africa and shows how programmable logic is successfully applied in an environment where ASIC designs are not yet feasible. Programmable logic is used in the courses for rapid prototyping of much more complex digital structures, much quicker and easier, than in the past. VHDL is used to describe digital and computer structures at algorithmic level. Stellenbosch University is the first university in Africa to introduce these concepts in engineering courses     

数字基带传输系统的研究与设计

本文介绍了设计高性能的数字基带传输系统的基本要求,重点分析如何采用数字滤波技术改善数字基带传输系统的性能,并提供了相关数字滤波器的数学模型与仿真。该仿真结果及结论对数字基带传输系统的模型设计与参数分析有着重要参考价值。     

Optical amplifier performance in digital optical communication systems

Contents  Optical amplifiers are important building blocks in nowaday's optical communication system. Their noise behavior differs considerably from that of electrical amplifiers. Theory is reviewed and supplemented by examples that allow to estimate the performance of optical transmission systems. In particular, a correct optical noise figure definition is explained. Received: 19 June 2000     

VHDL语言在电子设计自动化中的应用

介绍了VHDL语言及其基本特点和VHDL强大的仿真工具Active-VHDL，并结合例子描述了VHDL语言在数字电路设计仿真调试阶段所起的重要作用，仿真通过之后需要进行综合才能完成设计工作。结合使用VHDL的仿真和综合工具进行电子设计自动化设计的实际芯片取得了令人满意的结果。