CAD技术在模具制造中的应用

作为一种高附加值和高技术密集型产业,模具工业已成为当今工业发展的基础.而模具工业发展的关键主要依靠先进技术的应用,本文在介绍了模具制造技术的性质和特点的同时,试析现代模具设计、制造中应用的各种先进制造及CAD技术的应用,揭示了当前模具制造领域的发展方向.     

探析计算机在医院工作的应用

随着计算机信息技术的发展以及计算机的普及,其给社会各领域都带来了很大影响,计算机在医院中也得到了广泛的应用。现代计算机在医院工作中的应用主要集中于医院信息系统的建立,其包括计算机医学图像管理系统、计算机监护分析系统、计算机病历管理系统、计算机医疗仪器管理系统等,计算机在医院的应用还有更加广阔的前景,数字化医院是计算机在医院中未来应用的发展趋势。     

A two-stage hardware scheduler combining greedy and optimal scheduling

Greedy scheduling heuristics provide a low complexity and scalable albeit particularly sub-optimal strategy for hardware-based crossbar schedulers. In contrast, the maximum matching algorithm for Bipartite graphs can be used to provide optimal scheduling for crossbar-based interconnection networks with a significant complexity and scalability cost. In this paper, we show how maximum matching can be reformulated in terms of Boolean operations rather than the more traditional formulations. By leveraging the inherent parallelism available in custom hardware design, we reformulate maximum matching in terms of Boolean operations rather than matrix computations and introduce three maximum matching implementations in hardware. Specifically, we examine a Pure Logic Scheduler with three dimensions of parallelism, a Matrix Scheduler with two dimensions of parallelism and a Vector Scheduler with one dimension of parallelism. These designs reduce the algorithmic complexity for an N×N$N\times N$ network from O(N³)$O\left(N^3\right)$ to O(1)$O\left(1\right)$, O(K)$O\left(K\right)$, and O(KN)$O\left(KN\right)$, respectively, where K$K$ is the number of optimization steps. While an optimal scheduling algorithm requires K=2N−1$K=2N-1$ steps, by starting with our hardware-based greedy strategy to generate an initial schedule, our simulation results show that the maximum matching scheduler can achieve 99% of the optimal schedule when K=9$K=9$. We examine hardware and time complexity of these architectures for crossbar sizes of up to N=1024$N=1024$. Using FPGA synthesis results, we show that a greedy schedule for crossbars, ranging from 8×8 to 256×256, can be optimized in less than 20 ns per optimization step. For crossbars reaching 1024×1024 the scheduling can be completed in approximately 10 μs with current technology and could reach under 90 ns with future technologies.     

Extended stochastic gradient identification algorithms for Hammerstein–Wiener ARMAX systems

An extended stochastic gradient algorithm is developed to estimate the parameters of Hammerstein–Wiener ARMAX models. The basic idea is to replace the unmeasurable noise terms in the information vector of the pseudo-linear regression identification model with the corresponding noise estimates which are computed by the obtained parameter estimates. The obtained parameter estimates of the identification model include the product terms of the parameters of the original systems. Two methods of separating the parameter estimates of the original parameters from the product terms are discussed: the average method and the singular value decomposition method. To improve the identification accuracy, an extended stochastic gradient algorithm with a forgetting factor is presented. The simulation results indicate that the parameter estimation errors become small by introducing the forgetting factor.     

基于MVC架构的网络设计研究

随着互联网和商业软件的发展,基于网络的应用系统越来越多,MVC架构能有效的缩短开发成本和开发时间,该文主要介绍MVC架构的几种主要模式,根据网络应用系统的特点．介绍如何在网络应用系统中实现MVC架构。     

Tuning On-Air Signatures for Balancing Performance and Confidentiality

In this paper, we investigate the trade off between performance and confidentiality in signature-based air indexing schemes for wireless data broadcast. Two metrics, namely, false drop probability and false guess probability, are defined to quantify the filtering efficiency and confidentiality loss of a signature scheme. Our analysis reveals that false drop probability and false guess probability share a similar trend as the tuning parameters of a signature scheme change and it is impossible to achieve a low false drop probability and a high false guess probability simultaneously. In order to balance the performance and confidentiality, we perform an analysis to provide a guidance for parameter settings of the signature schemes to meet different system requirements. In addition, we propose the jump pointer technique and the XOR signature scheme to further improve the performance and confidentiality. A comprehensive simulation has been conducted to validate our findings.     

多工作模式产品配色意象的灰色评价方法

针对产品开发过程中的色彩规划问题,考虑多工作模式产品的配色特征,构建一种多工作模式产品的配色意象评价模型.基于灰色关联分析法建立产品方案色彩与意象之间的关联模型,运用灰色聚类法判断产品配色方案的意象值;将产品各工作模式下的配色意象同时作为评价属性并赋予相应的权值,进行综合评价.文中方法兼顾了多工作模式产品色彩面积的可变性和消费者主观意象的不确定性,将多工作模式产品的配色意象评价方法置于灵活、直观的框架中.最后以工程机械产品为应用实例,证明该方法较单属性评价方法更为贴近消费者的主观意象.     

一个新的基于权限的委托模型CPPBDM

基于权限的委托模型PBDM实现了权限的委托,其实现方法是将角色进行划分,使组织的角色继承关系变得复杂,模型的实现和管理变得烦琐.为此,提出对PBDM进行改进的基于权限划分的新模型CPPBDM,模型引入新的角色间关系:委托继承、激活指派;新模型能够实现基于权限的委托与角色代理,简化了模型的实现与管理.     

一种空间自适应正则化MAP超分辨率重建算法

提出一种简单、通用的基于正则化技术的自适应MAP超分辨率重建算法。与以往算法不同,该方法引入了局部空间自适应正则化参数,弥补了传统算法对图像自身的局部特性缺乏考虑的不足。算法通过迭代的方式,利用中间重建结果不断对正则化参数进行更新,并最终得到重建图像。实验结果表明,该方法可以根据不同图像序列的特点以及图像的局部灰度特性,自适应地确定相应的正则化参数,并找到最优解,有效地保护了高分辨率图像的细节信息。     

利用POMDP模型来增强分布式系统的生存性

针对分布式系统存在的状态信息不完全问题,引入部分可观察的马尔可夫决策过程(POMDP)模型到生存控制系统中.在该控制系统的构造过程中,结合前瞻的思想,提出一种简易、有效的搜索算法(NSL算法)来作出决策,从而在一定程度上弥补了现有生存控制系统的不足,提高了分布式系统的可生存性.