DCT域数字水印算法的FPGA实现

提出一种基于DCT域的数字水印算法,并用FPGA硬件实现其中关键部分DCT变换。采用VHDL语言有效设计和实现DCT变换,分析与仿真结果表明:与软件实现相比,用FPGA实现水印算法具有高速实时处理的优点。因此,该设计是一种很有吸引力的硬件实现解决方案。     

可靠多播方案的最佳有效负载长度研究

以保证可靠分发所需总传输时间为评判标准,在考虑分组头开销的条件下,研究了基于简单反馈重传、RS码(Reed-Solomon code)和LT喷泉码技术的3种多播方案中的有效负载长度选取问题,提出了通过理论分析确定最佳有效负载长度的方法,并以仿真实验进行验证。理论分析和仿真实验表明,对于不同的分组头大小和链路误比特率,各方案的有效负载长度均具有最佳取值;链路误比特率越高,最佳有效负载长度所带来的性能增益越明显。其中,基于LT喷泉码的可靠多播方案性能最优。     

基于Web Services的管控一体化

基于Web Services的管控一体化系统,由服务实现层及应用层组成.实现层提供服务,其远程工控服务系统含监控设备和监控模块,管理系统含管理模块和数据源.应用层包括UDDI注册中心、SOAP路由器、服务组合库、实时处理系统、用户界面等.以一制造执行系统为例,采用Microsoft技术构建,其管理服务含生产计划及质量管理模块.每条生产线生产过程控制各由一个控制服务模块提供,信息实时处理器通过用户界面向管理员提供服务.     

MODEL-BASED DEVELOPMENT OF REAL-TIME SOFTWARE SYSTEM FOR ELECTRONIC UNIT PUMP SYSTEM

A real-time operating system (RTOS), also named OS, is designed based on the hardware platform of MC68376, and is implemented in the electronic control system for unit pump in diesel engine. A parallel and time-based task division method is introduced and the multi-task software architecture is built in the software system for electronic unit pump (EUP) system. The V-model software development process is used to control algorithm of each task. The simulation results of the hardware-in-the-loop simulation system (HILSS) and the engine experimental results show that the OS is an efficient real-time kernel, and can meet the real-time demands of EUP system; The built multi-task software system is real-time, determinate and reliable. V-model development is a good development process of control algorithms for EUP system, the control precision of control system can be ensured, and the development cycle and cost are also decreased.     

基于WebGIS的水文信息查询系统的设计与实现

以福建省为例,探索了WebGIS支持下的水文信息查询系统的建设,并对系统建设中的WebGIS平台选择、体系结构设计、系统开发方案配置、系统数据组织,以及系统的功能实现进行了介绍。系统的建设提高了水文、防汛等相关部门的工作效率和科学性,推动了福建省水文信息化建设的进程,拓宽了WebGIS的应用领域。     

Reliability of dynamic systems in random environment by extreme value theory

A practical method is developed for estimating the performance of highly reliable dynamic systems in random environment. The method uses concepts of univariate extreme value theory and a relatively small set of simulated samples of system states. Generalized extreme value distributions are fitted to state observations and used to extrapolate Monte Carlo estimates of reliability and failure probability beyond data. There is no need to postulate functional forms of extreme value distributions since they are selected by the estimation procedure. Our approach can be viewed as an alternative implementation of the method in [7] for estimating system reliability. Numerical examples involving Gaussian and non-Gaussian system states are used to illustrate the implementation of the proposed method and assess its accuracy.     

Balancing reduction of linear systems having multiple delays

Abstract

In this paper we apply the balancing reduction method to derive reduced‐order models for linear systems having multiple delays. The time‐domain balanced realization is achieved through computing the controllability and observability gramians in the frequency domain. With the variable transformation s = i tan(θ/2), the gramians of linear multi‐delay systems can be accurately evaluated by solving first‐order differential equations over a finite domain. The proposed approach is computationally superior to that of using the two‐dimensional realization of delay differential systems.     

选煤厂虚拟现实仿真系统的设计与实现

文章介绍了基于虚拟现实技术开发的选煤厂虚拟现实仿真系统的架构及其关键技术,详细阐述了仿真系统的实现方式。     

Reconstruction of graphs based on random walks

The analysis of complex networks is of major interest in various fields of science. In many applications we face the challenge that the exact topology of a network is unknown but we are instead given information about distances within this network. The theoretical approaches to this problem have so far been focusing on the reconstruction of graphs from shortest path distance matrices. Often, however, movements in networks do not follow shortest paths but occur in a random fashion. In these cases an appropriate distance measure can be defined as the mean length of a random walk between two nodes — a quantity known as the mean first hitting time.In this contribution we investigate whether a graph can be reconstructed from its mean first hitting time matrix and put forward an algorithm for solving this problem. A heuristic method to reduce the computational effort is described and analyzed. In the case of trees we can even give an algorithm for reconstructing graphs from incomplete random walk distance matrices.     

基于XML动态网站的架构与实现

基于XML的动态网站解决了传统的web网站的客户端无法一次传送太多数据的问题，实现了XML数据的双向传递，大大减轻了服务器的工作量，达到平衡传送与接收端工作量的目标。