The operational semantics of user-defined relationships in object oriented database systems

In semantic data models, abstract relationship (e.g. generalization, aggregation, etc.) semantics are defined, specifying how insertion, deletion and modification operations made at a higher level of abstraction can affect the objects abstracted over and vice versa. These semantics, also known as structural constraints, are expressed through so-called update rules. This perspective has been somewhat lost in most object-oriented systems, where user-defined relationships are supported as simple pointers and their semantics are embedded, distributed and replicated within the operations accessing these pointers. This paper inherits and extends the treatment of relationships found in semantic data models to behavioural object-oriented models by presenting an approach to uniformly capture the update rules for user-defined relationships. The stress is not on supporting relationships as first-class objects, but on describing their update rules (or operational semantics) through a set of constructors namely, reaction, anticipation, delegation and exception. The approach has been borne out by an implementation in an active object-oriented database system.     

多站远程无线控制信号系统通信软件的开发

多站远程无线控制系统是以计算机为中心控制 ,用多个信号源作为下位机通过无线模块进行通信 ,文中介绍了通过无线数传模块实现无线通讯以及ActiveX控件的使用方法 ,提出了使系统应用程序更安全可靠 ,效率更高 ,维护更加方便的几种措施。     

柯伐镀金盖板电化学腐蚀的剖析及其防腐措施

对半导体器件封装的气密性失效进行了研究。发现，柯伐镀金盖板遭致电化学腐蚀是导致气密性失效的主要原因。对电解液的形成和电化学腐蚀机理进行了深入的分析。提出了防止腐蚀，提高器件气密可靠性的思路和方法。     

基于COM＋技术的Web服务封装研究

早期的信息管理系统都是用于实现企业特定的业务功能而建立的,包括对企业生产、供应、销售以及客户服务等的控制和管理。企业按照职能部门建立了各种企业信息系统,这些信息管理系统被其所在部门所使用,并在实际的工作生产中发挥了巨大作用。该文从整体考虑各个企业信息管理系统,并根据具体业务的需求对这些系统进行统一编排,通过一个合适的集成平台把现有企业信息管理系统进行有机的整合起来,使各＂信息孤岛＂联系起来。     

基于MPC850 VxWorks系统的BSP设计

首先介绍嵌入式系统VxWorks及其启动过程;分析了基于MPC 850最小系统的硬件和BSP的执行流程;重点研究了MPC850BSP的设计与应用程序加载,包括其硬件驱动程序的设计、应用程序加载、建立调试环境和target server的配置等;基于MPC850系统的Vxworks BSP调试平台的实现,对Vxworks上层应用软件和底层硬件驱动的并行开发有着很重要的意义。     

单周期控制Boost—PFC基于Saber的设计与仿真

单周期控制策略简单可靠,动态响应速度快,能很好地抑制输入电压扰动和负载突变。本文阐述了单周期控制Boost—PFC的工作原理,对单周期控制Boost—PFC进行了基于Saber软件的CAD设计和仿真。仿真结果表明,单周期控制适用干Boost变换器,能够实现功率因数校正。     

移动终端智能应答系统的实现

本系统针对当前移动手机用户在不方便接听、不愿意接听电话例如在开会、开车等各种各样的情形下．通过委婉的方式表达个人处境,达到礼貌告知对方的目的而开发的智能应答系统。业务的基本模式就是捕获到用户忙的事件,如果可能还需要区分是用户通话忙还是拒接忙,然后通过USSD向被叫推送一个提示如何回复用户的操作菜单,最后通过被叫用户的选择,给主叫用户一个答复,例如一个预定义的短信、IVR放音、转接语音信箱等多种方式。     

企业信息安全事件控制方案研究

结合企业信息突发事件应急响应的实际情况,分析了目前常见的信息安全事件,提出了在事件控制中采用的关键技术及有效的防范措施。     

Evaluating a color-based active basis model for object recognition

Wu and coworkers introduced an active basis model (ABM) for object recognition in 2010, in which the learning algorithm tends to sketch edges in textures. A grey-value local power spectrum was used to find a common template and deformable templates from a set of training images and to detect an object in new images by template matching. In this paper, we propose a color-based active basis model (color-based ABM for short), which incorporates color information. We adopt the framework of Wu et al. in the learning, detection, and classification of the color-based ABM. However, in order to improve the performance in object recognition, we modify the framework of Wu et al. by using different color-based features in both the learning and template matching algorithms. In this color-based ABM approach, two types of learning (i.e., supervised learning and unsupervised learning) are also explored. Moreover, the usefulness of the color-based ABM for practical object recognition in computer vision applications is demonstrated and its significant improvement in recognizing objects is reported.     

A framework for avoiding steganography usage over HTTP

Steganographic techniques allow users to covertly transmit information, hiding the existence of the communication itself. These can be used in several scenarios ranging from evading censorship to discreetly extracting sensitive information from an organization. In this paper, we consider the problem of using steganography through a widely used network protocol (i.e. HTTP). We analyze the steganographic possibilities of HTTP, and propose an active warden model to hinder the usage of covert communication channels. Our framework is meant to be useful in many scenarios. It could be employed to ensure that malicious insiders are not able to use steganography to leak information outside an organization. Furthermore, our model could be used by web servers administrators to ensure that their services are not being abused, for example, as anonymous steganographic mailboxes. Our experiments show that steganographic contents can be successfully eliminated, but that dealing with high payload carriers such as large images may introduce notable delays in the communication process.