基于Delphi的自定义预览报表的设计与实现

阐述了在Delphi环境下开发自定义预览报表的设计方法,即利用Delphi 提供的Quickrep和QRpreview控件,通过设定预览报表的尺寸大小和缩放比例等来生成预览报表。编程实现自定义预览报表的具体步骤包括创建预览报表、使用预览控制元件、在OnMouseDown事件中编写程序代码等。自定义预览报表改变了Delphi缺省的预览报表格式,是Delphi中实现特殊格式报表的有效补充。     

程序设计语言FORTRAN90研究与应用

ＦＯＲＴＲＡＮ９０标准较以往的版本有了重大改进,它吸收了其它编程语言（如：Ｃ及Ｐａｓｃａｌ）的优点,并创建了许多新特性。如：用简明有效的符号形式处理数组及使用用户自定义类型数据。前者使对许多数学问题处理的程序代码变得极为简单,且由于其数值的特性与计算机硬件资源匹配更好,使ＦＯＲＴＲＡＮ语言成为大型计算机理更有效的语言;后者使编程人员能够按照问题所需要的数据类型来编程。     

Secure access of resources in software‐defined networks using dynamic access control list

Software‐defined networking (SDN) creates a platform to dynamically configure the networks for on‐demand services. SDN can easily control the data plane and the control plane by implementing the decoupling concept. SDN controller will regulate the traffic flow and creates the new flow label based on the packet dump received from the OpenFlow virtual switches. SDN governs both data information and control information toward the destination based on flow label, but it does not contain security measure to restrict the malicious traffic. The malicious denial‐of‐service (DoS) attack traffic is generated inside the SDN environment; it leads to the service unavailability. This paper is mainly focused on the detection of DoS attacks and also mitigates the malicious traffic by dynamically configuring the firewall. The SDN with dynamic access control list properties is emulated by mininet, and the experimental results exemplify the service unavailable gap between acceptance and rejection ratio of the packets.     

基于数据库应用的计算逻辑的实现

在基于数据库的应用系统中,存在着许多数据间的关系,一部分可以通过数据库本身的机制来实现,如主外码引用关系,而另一部分关系是数据库无法维护的,如"进销存"计算关系,目前都是程序员编写代码去实现所需要的这部分关系,而基于代码的实现不利于计算关系的变更和扩展,需要有一种好的便于后期维护的实现方法.     

基于SCA的软件无线电SoPC设计

软件通信体系架构为实现具有开放性、标准化、模块化的通用软件无线电平台提供了规范。为了实现无线通信系统的小型化,采用软硬件协同设计的方法构建了基于SCA的软件无线电SoPC系统,该系统实现了波形组件的动态配置和部署,以及硬件组件的部分重构。同时它具有效率高,体积小,功耗低,功能强的优点,具有很好的应用前景。     

未来网络体系架构研究综述

现有互联网正面临着前所未有的挑战,包括可扩展性、安全性、管控性、移动性、内容分发能力、绿色节能等一系列问题,难以通过增量式的研究模式彻底解决。在这样的背景下,创新型的未来网络体系架构研究成为当前全球关注的热点领域。通过介绍全球在该领域的研究进展情况,阐述当前该领域主要的研究成果,总结分析该领域的研究发展趋势与核心问题,期望对国内该领域的研究起到参考和帮助。     

“软件定义网络”线上线下混合式实验教学的探索和实践

以深入理解SDN技术基本原理和解决当前网络存在的问题为出发点,结合线上线下实验资源,设计了虚拟型和实体型两大类实验项目,每类实验均有基本型和创新型。虚拟实验基本型有基于浏览器的线上和基于本地虚拟机的线下实验,创新型实验使学生掌握SDN应用开发的基本流程。实体实验基本型包括三种类型实体SDN交换机实验,创新型实验以解决网络实际问题为目标。实验结果显示,分类实验较好地满足了不同学生的实践需求。     

Partially defined computer instructions and guards

We here extend our earlier work on the theory of computer instructions to consider instructions which are only partially defined. For every such instruction, we assume that it is defined whenever a certain Boolean expression is true; we refer to such a Boolean expression as a guard, following Dijkstra. This is a special case of a more general function on the set of states of a computer, representing an expression in a programming language. Many constructs for instructions now generalize to partially defined instructions; in particular, we define the notion of conditional input and output regions, as well as the relevant region of a more general expression. Fundamental theorems about instructions generalize to theorems about guards and about partially defined instructions. We also define the parallel execution of such instructions, which is useful in validating a generalized instruction commutativity criterion.     

A time bound on the materialization of some recursively defined views

A virtual relation (or view) can be defined with a recursive Horn clause that is a function of one or more base relations. In general, the number of times such a Horn clause must be applied in order to retrieve all the tuples in the virtual relation depends on the contents of the base relations of the definition. However, there exist Horn clauses for which there is an upper bound on the number of applications necessary to form the virtual relation, independent of the contents of the base relations. Considering a restricted class of recursive Horn clauses, we give necessary and sufficient conditions for members of the class to have this bound.This research was supported by the National Science Foundation under Grant ECS-8300463.     

Programmable Adaptive Security Scanning for Networked Microgrids

Communication-dependent and software-based distributed energy resources (DERs) are extensively integrated into modern microgrids, providing extensive benefits such as increased distributed controllability, scalability, and observability. However, malicious cyber-attackers can exploit various potential vulnerabilities. In this study, a programmable adaptive security scanning (PASS) approach is presented to protect DER inverters against various power-bot attacks. Specifically, three different types of attacks, namely controller manipulation, replay, and injection attacks, are considered. This approach employs both software-defined networking technique and a novel coordinated detection method capable of enabling programmable and scalable networked microgrids (NMs) in an ultra-resilient, time-saving, and autonomous manner. The coordinated detection method efficiently identifies the location and type of power-bot attacks without disrupting normal NM operations. Extensive simulation results validate the efficacy and practicality of the PASS for securing NMs.