International high technology cooperation: lessons learned

In February 1986, in response to the Nunn Amendment in the United States, a special Conference of National Armaments Directors (CNAD) examined possible ways to foster cooperative high technology research and development programs within the NATO Alliance. As a result, they established the Special Working Group on Ada Programming Support Environments (SWG APSE) to oversee the development of a multinational software development environment for developing real-time weapon systems in the Ada programming language. The Working Group also developed a requirements specification for a software development environment interface standard. The author describes the benefits and pitfalls of this joint software development. He also describes the lessons learned from such joint multinational development efforts. Further, the author describes the management issues that are unique to such an international collaborative effort and gives a frank assessment of the techniques that had helped and hindered the program's progress     

An Ada-compatible distributed database management system

Adaplex is an integrated language for programming database applications. It results from the embedding of the database sublanguage Daplex in the general-purpose programming language Ada [1]. This paper describes the design of DDM, a general-purpose distributed database management system implemented in Ada that supports the use of Adaplex as interface language. There are two novel aspects in the design of this system. First, this is the first full-scale distributed database system to support a semantically rich, functional data model. DDM goes beyond systems like Distributed INGRES and R^*(which are based on the relational technology) in providing advanced data modeling capabilities and ease of use. Second, this is the first full-function distributed DBMS designed to be compatible with the Ada programming environment. The coupling between Ada and Daplex has been achieved at the expression level which is much tighter than the statement level integration attained in previous systems. This tight coupling poses new implementation problems but also creates new opportunities for optimization. The current paper highlights the Adaplex language and discusses innovative aspects in DDM's design that are intended to meet the dual objectives of good performance and high data availability.     

Ada technology: current status and cost impact

It is noted that relatively few commercial practitioners have embraced Ada, chiefly because of the lack of efficient compilers and the high initial cost of using it. The results of efforts to address these concerns are summarized. Several Ada compilers targeted to different commercial microprocessors have been benchmarked. This benchmarking activity included obtaining the execution time as well as the memory requirements of Ada compilers and comparing them with compilers for traditional languages like Pascal. In order to determine the cost impact of using Ada, a model has been developed from first principles. The model predicts the cost of using Ada compared to other high languages encompasses the developmental phase as well as the maintenance phase. The model is further refined to include the impact of reusing software. On the basis of these data, it is concluded that Ada technology has matured enough to be used in the embedded environment and can represent a potential cost savings compared to other languages over the entire life cycle     

一种Ada并发程序的模型检测方法

提出了一种针对Ada并发程序的模型提取方法,使用模型检测工具SPIN对生成的模型进行自动化验证,发现Ada语言编写的程序中并发错误。通过实例对提取方法进行验证,实验结果表明,此方法能够成功检测出Ada并发程序中存在的错误,并给出相应的错误路径。     

Keil Cx51在激光测距机中的应用

以激光测距机技术的发展为背景,通过分析指出目前汇编语言编程已不能满足当前测距机的技术发展需求,需要采用新的编程语言对测距机进行开发,以进一步提高开发的效率。文中对Keil C语言的功能特点进行了简单的介绍,指出Keil C具有强大的功能,并结合工程实践,介绍了其对激光测距机编程的技巧及注意事项。以采用Keil C进行软硬件开发的某激光测距机终端机为例,简要介绍了Keil C开发的流程及其体现出的优点。最后对采用Keil C开发测距机的特点进行了总结,提出了采用Keil C开发激光测距机不但是可行的,而且应该加以推广。     

Partitioned k-Exclusion Real-Time Locking Protocol Motivated by Multicore Multi-GPU Systems

Graphic processing units (GPUs) have been widely recognized as cost-efficient co-processors with acceptable size, weight, and power consumption. However, adopting GPUs in real-time systems is still challenging, due to the lack in framework for real-time analysis. In order to guarantee real-time requirements while maintaining system utilization in modern heterogeneous systems, such as multicore multi-GPU systems, a novel suspension-based k-exclusion real-time locking protocol and the associated suspension-aware schedulability analysis are proposed. The proposed protocol provides a synchronization framework that enables multiple GPUs to be efficiently integrated in multicore real-time systems. Comparative evaluations show that the proposed methods improve upon the existing work in terms of schedulability.     

Live soundscape composition based on synthetic emotions

We conceived Ada: Intelligent Space exhibit as an artificial organism, integrating a large number of sensory modalities, and let it interact with visitors using a multitude of effector systems. Ada used a language of sound and light to communicate its moods, emotions, and behaviors. Here we describe the mechanisms behind Ada's sound communication, its real-time performance, and its interpretation by human subjects.     

基于COM 组件的面向信号雷达测试系统软件平台设计

为解决雷达测试系统测试程序(TP)可移植性,简化测试程序流程,研究了面向信号测试、自动测试标记语言和图形化编程技术,开发了基于组件对象模型(COM)的面向信号雷达测试系统通用软件平台。该平台以图形化的开发方式,实现了面向信号的COM 组件和测试流程设计、开发与调试,主要用于雷达整机、单元和板级测试系统,加速雷达测试系统TP开发,降低TP 设计师的编程技术要求。     

基于AD9951的通用信号源设计

直接数字频率合成(DDS)是频率合成领域中的一项新技术,利用集成DDS芯片能够满足高性能信号源的设计要求。简要介绍了DDS集成芯片AD9951的基本原理及功能特性。提出了一种以AD9951为核心,利用单片机控制技术的通用信号源设计方法。给出了系统主要硬件电路的实现,并利用汇编语言开发了主控软件。实验结果表明,硬件电路结构简单,软件控制灵活,软件和硬件拓展性好,输出信号频率稳定,分辨率高。     

Design, implementation, and experiences of the OMEGA end-pointarchitecture

The OMEGA architecture provides end-to-end quality-of-service (QoS) guarantees for distributed applications. QoS parameters are translated between application and network requirements by the QoS broker, thus integrating media and network QoS management into a single entity. Admission control uses a schedulability test derived from application requirements. A novel task priority and precedence-based scheme is used to represent complex application requirements and ensure correct feasible schedules. A prototype of OMEGA has been implemented using workstations connected by a 155 Mb/s dedicated ATM local-area network (LAN). To simplify implementation, we assumed networked multimedia application with periodic media streams, specifically a master/slave telerobotics application. This application employs media with highly diverse QoS requirements (e.g., interarrival times, loss rate, and bandwidth) and therefore provides a good platform for testing how closely one can achieve QoS guarantees with workstation hosts and cell-switching. Experience with this implementation has helped to identify new challenges to extending these techniques to a larger domain of applications and systems, and suggests promising new research questions     

基于标准单元布图模式的电源线/地线网络设计、优化和验证集成工具

介绍了一个基于标准单元布图模式的电源线 /地线网络的辅助设计集成工具 .它应用了一系列高效的算法 ,为用户提供了电源线 /地线网络的设计、优化和验证的功能 .非线性优化技术、分枝定界算法和不完全乔莱斯基分解的预优共轭梯度法是该工作的三个主体部分 .用户可以选择使用非线性规划的方法或者几种分枝定界方法来满足他们对于精度和速度方面的不同需求 .实验结果表明 ,文中所提供的算法可以在很快的运行速度下实现更低的布线资源占用 .因此 ,在这些有效算法基础上实现的辅助设计工具具有处理大规模电路的能力.     

基于标准单元布图模式的电源线/地线网络设计、优化和验证集成工具

介绍了一个基于标准单元布图模式的电源线/地线网络的辅助设计集成工具.它应用了一系列高效的算法,为用户提供了电源线/地线网络的设计、优化和验证的功能.非线性优化技术、分枝定界算法和不完全乔莱斯基分解的预优共轭梯度法是该工作的三个主体部分.用户可以选择使用非线性规划的方法或者几种分枝定界方法来满足他们对于精度和速度方面的不同需求.实验结果表明,文中所提供的算法可以在很快的运行速度下实现更低的布线资源占用.因此,在这些有效算法基础上实现的辅助设计工具具有处理大规模电路的能力.     

Python语言的Web开发应用分析

随着人工智能时代的到来,计算机编程成为引领科技改革的主要力量,Python语言作为计算机编程技术的佼佼者,在Web开发领域有着得天独厚的优势。Python是一种通用型、解释型语言,自身带有庞大的标准库,可操作性比较强,可以快速设计出计算机程序,有效提升程序设计效率。程序员可以利用Python语言来开发Web,利用Python脚本来运行程序,利用标准库快速进行数据分析和整理,提升程序计算效率,利用Python语法结构来构建Web架构,让Web运行更加流畅,进一步推广Python编程技术。     

计算经济模式下的动态网格资源调度算法研究

在计算经济模式下，为调节网格资源供需分配提出了一个基于用户服务需求的计算经济框架。这个框架通过经济学驱动截止期和预算约束根据用户的需求，分配资源到应用任务。提出了一种基于计算经济的网格资源动态调度算法，主要针对网格资源由于计算能力不同而花费代价不同而提出，利用启发式搜索技术，综合考虑了任务的截止期、预算约束、最早可能执行时间等不同因素，通过一个新的资源分配策略实现了时间一代价的最优化．提高了资源调度的成功率。     

X3D: Extensible 3D Graphics Standard [Standards in a Nutshell]

Extensible 3D (X3D) is the open standard for Web-delivered three-dimensional (3D) graphics. It specifies a declarative geometry definition language, a run-time engine, and an application programming interface (API) that provide an interactive, animated, real-time environment for 3D graphics. The X3D specification documents are freely available, the standard can be used without paying any royalties, and numerous implementations are available.     

Energy efficient semi-partitioned scheduling for embedded multiprocessor streaming systems

In this paper, we study the problem of energy minimization when mapping streaming applications with throughput constraints to homogeneous multiprocessor systems in which voltage and frequency scaling is supported with a discrete set of operating voltage/frequency modes. We propose a soft real-time semi-partitioned scheduling algorithm which allows an even distribution of the utilization of tasks among the available processors. In turn, this enables processors to run at a lower frequency, which yields to lower energy consumption. We show on a set of real-life applications that our semi-partitioned scheduling approach achieves significant energy savings compared to a purely partitioned scheduling approach and an existing semi-partitioned one, EDF-os, on average by 36 % (and up to 64 %) when using the lowest frequency which guarantees schedulability and is supported by the system. By using a periodic frequency switching scheme that preserves schedulability, instead of this lowest supported fixed frequency, we obtain an additional energy saving up to 18 %. Although the throughput of applications is unchanged by the proposed semi-partitioned approach, the mentioned energy savings come at the cost of increased memory requirements and latency of applications.     

A language for compositional specification and verification offinite state hardware controllers

The authors consider the state machine language (SML) for describing complex finite state hardware controllers. It provides many of the standard control structures found in modern programming languages. The state tables produced by the SML compiler can be used as input to a temporal logic model checker that can automatically determine whether a specification in the logic CTL is satisfied. The authors describe extensions to SML for the design of modular controllers. These extensions allow a compositional approach to model checking which can substantially reduce its complexity. To demonstrate these methods, the authors discuss the specification and verification of a simple central-processing-unit (CPU) controller     

Schedulability analysis of real-time traffic in WorldFIP networks: an integrated approach

The WorldFIP protocol is one of the profiles that constitute the European fieldbus standard EN-50170. It is particularly well suited to be used in distributed computer-controlled systems where a set of process variables must be shared among network devices. To cope with the real-time requirements of such systems, the protocol provides communication services based on the exchange of periodic and aperiodic identified variables. The periodic exchanges have the highest priority and are executed at run time according to a cyclic schedule. Therefore, the respective schedulability can be determined at pre-run-time when building the schedule table. Concerning the aperiodic exchanges, the situation is different since their priority is lower and they are bandied according to a first-come-first-served policy. In this paper, a response-time-based schedulability analysis for the real-time traffic is presented. Such analysis considers both types of traffic in an integrated way, according to their priorities. Furthermore, a fixed-priorities-based policy is also used to schedule the periodic traffic. The proposed analysis represents an improvement relative to previous work and it can be evaluated online as part of a traffic online admission control. This feature is of particular importance when a planning scheduler is used, instead of the typical offline static scheduler, to allow online changes to the set of periodic process variables.     

物联网硬实时控制系统中可调度性分析方法的研究

建立了具有反馈型和非反馈型任务的物联网硬实时控制系统——混合控制任务系统(hybrid controlling task system,HCTS)的任务模型,以全面准确地描述系统中不同任务的结构、交互模式和运行特征,并提出了一种新的响应时间分析方法,用于验证系统是否满足实时性要求.实验结果表明,HCTS中的任务具有较小的平均最差情况下的响应时间,但是在反馈次数较多的情况下对任务的实时性具有不利影响,从而为HCTS的优化提供了支持.