Changing safety-critical software

Changing software to implement new features, correct problems, update functions, or replace obsolete hardware components (e.g., microprocessors) is a way of life in today's industry. A systematic software change process is essential for the maintenance and reuse of safety-critical software. This paper presents activities to consider when changing software in safety-critical systems. The focus is on the aviation industry; however, the concepts are also applicable to other safety-critical domains, such as medical or nuclear     

It is software process, stupid: next millennium software qualitykey

The economic impacts of software in our economy are discussed. The current economic state has been attributed to the Information Technology which has not only generated a large number of jobs but also contributed to the productivity and quality of the operations in our digital economy. The next millennium will be digital and obviously software has a very important role to play in our personal, national, and international scenes. Software will be essential in all our products from Space Station and airplanes to automobiles, television, pagers, and cellular telephones, For any organization, for that matter, even nations to succeed in the digital millennium software will be very essential. One who develops software better, cheaper, and faster will become the leader with enormous economic advantage. The key to success in software development will depend upon the software processes used to build them. Many national and international organizations have developed models based on processes to improve quality, productivity and cycle time of software development. Software Engineering Institute's Capability Maturity Model (CMM) is one such model. CMM helps in assessing the software processes and their capabilities and continuously improve them to higher levels of maturity. Similarly, ISO 9000 and the related ISO 9001 for software quality are based on software processes. This paper will bring out the importance of software processes particularly in managing the quality of software based on national and international initiatives     

Real-time software failure characterization

A series of studies aimed at characterizing the fundamentals of the software failure process has been undertaken as part of a NASA project on the modeling of a real-time aerospace vehicle software reliability. An overview of these studies is provided, and the current study, an investigation of the reliability of aerospace vehicle guidance and control software, is examined. The study approach provides for the collection of life-cycle process data, and for the retention and evaluation of interim software life-cycle products     

TDMS for aviation software

Quality assurance and testing phase is one of the most crucial phases in the life cycle of computer software. Most aviation software, due to the possible life-threatening consequences of failures, is subjected to intense testing. Frequently, this results in generation of enormous unorganized raw data files. Such data needs to be further processed and analyzed to get a meaningful insight into potential problem areas with the software. In this paper, we present the results of our study on designing and implementing a test management system specifically designed for testing aviation software. The paper has three major contributions. First, we present a survey of existing work. Second, we discuss the design for a test data management system, TDMS. Finally, we discuss some implementation issues encountered during the TDMS development.     

Lithium-ion battery software safety protection

Production Li-ion batteries include hardware and software safety protection. The hardware protection includes PTC (positive temperature coefficient) thermistor switch, electrical circuit disconnect and rupture vent. The software protection involves a charging algorithm (charging to ultimate voltage), which is used with internal electrical circuitry (cell voltage control and equalization circuit). This paper discusses a specific charging algorithm and additional software protection features associated with hard, soft and chemical shunt recognition     

军用嵌入式软件的可靠性分析

论述了军用软件的特点,对软件可靠性的性质和特征进行了具体分析,提出了提高军用软件可靠性的方法.     

Integrating system engineering software tools

System engineering projects typically involve the use of a variety of design, analysis, simulation, and management software tools that are home-grown or commercial-off-the-shelf (COTS). Very often, these applications are hosted on dissimilar computing platforms in a network environment. An application deployed on one platform may not be easily ported to another platform, and it usually cannot be readily accessed by software on the other platform. Enhancing the inter-operation among software applications or tools will greatly increase the effectiveness of the system engineering process. The middleware technology currently being developed by the computer industry promises to provide the needed software interface for integrating tools across a heterogeneous computer network. This paper discusses the experience of applying the middleware technology to software tools used in system engineering     

软件化雷达中的频率综合器

分析了雷达系统软件化对频率综合器提出的新要求,系统地归纳和总结了现有的频率合成技术,探讨了雷达软件化过程中频率综合器的设计,并提出了一种具体实现方案.     

快速发展中的无人机有效载荷

从近几年发生的战争实践来看,无人机已成为了一种能够搭载各类监测侦察设备和武器系统的低可探测性空中平台,而且随着微电子、信息和人工智能等技术的提高,无人机种类繁多、性能各异的有效载荷已进入了一个全新的迅速发展时期     

株洲通惠进展顺利

近年来中国经济强劲增长，国内公务机市场进入了快速发展阶段。普惠加拿大公司与中航工业集团公司已有超过30年的合作经验，非常看好中国公务航空产业的持续发展。为了满足未来中国通用及公务航空高速发展的需求，更好地为在中国以及亚太地区运营的民用型PT6A和PW100发动机提供维修服务，普惠加拿大在充分分析了未来市场需求的情况下，进行了早期的市场布局，于2011年宣布成立株洲通惠航空发动机有限公司（AEMC）。     

系统化软件复用的成功因素

本文根据国外一些著名软件企业在软件复用方面的实践经验,介绍了系统化软件复用方法，并对软件复用的成功因素进行了分析和评述。     

结冰模拟软件AERO-ICE中的关键数值方法

自然积冰对于航空飞行安全造成重大隐患,飞机在穿越富含过冷水汽的云层时冰形将按一定的物理规律积聚生长。介绍了一款三维结冰数值模拟软件AERO-ICE,该软件由网格自动生成、空气流场RANS计算、水滴场欧拉方法计算、结冰热力学分析四个模块组成。在空气流场计算方面,采用SPF k-v²-ω湍流模型,该模型引入湍流非平衡特性修正,预测的带冰翼型最大升力系数和失速攻角相对SA和SST模型有显著的提高。水滴场欧拉方程由于源项较大,迭代求解时容易发散,AERO-ICE软件采用流场光顺、二阶MUSCL空间离散以及LU-SGS隐式时间推进方法改善了数值稳定性。在结冰热力学分析模块,AERO-ICE软件同时具有Messinger与Myers模型,并将Messinger模型预估的壁面温度作为Myers模型的边界条件,从而解决了Myers模型温度设置的经验性问题。AERO-ICE软件支持多块网格、多重网格加速技术与大规模并行计算,其冰形计算结果得到了初步的验证。     

飞机维修思想的发展和应用

预防为主的维修思想 早期飞机由于发动机剩余功率较小,飞机的重量受限,航空技术装备不可能采用过多的余度,任何产品出了故障都有可能直接影响飞行安全.基于这种可靠性与安全性紧密联系,要求把维修工作放到故障发生的前面,进而广泛地采用预防性维修措施,即按固定时间进行翻修或报废."预防为主"的维修思想便在此背景下产生.     

机载探测系统的最新发展

现代战争战场环境日益复杂和严酷,它对各类军用飞机平台的目标探测、瞄准能力提出了更高的要求。随着探测器技术的进步和网络的不断扩展,出现了集红外/光电摄像机和激光器为一体的新一代轻型机载探测系统,装备这种系统的飞行平台也从单一的战术系统变为一种战略资源     

The conundrum of software estimation models

There are many sophisticated models and methods for estimating the size, cost, and schedule of software projects. However, the ability to accurately estimate software cost, size, or schedule is still dubious. In general, the predictive accuracy of models for estimating software development cost and schedule has not been shown to be better than “within 25 percent of actual cost or schedule, about one half of the time”, especially for Department of Defense software efforts. The same is true for software size estimating models and methods, although there are some studies that have shown superior results. For software support (or maintenance) cost estimation, no model has been demonstrated to be accurate. This paper presents a summary of efforts performed to date which demonstrate the accuracy (or lack thereof) of software models. The results of several studies in the areas of software development cost and schedule estimation, size estimation, and support cost estimation are presented to show what these models can and cannot do. Some ideas for improvement are also presented, including the results of some studies which may lead to a resolution of the accuracy conundrum which currently exists     

An alternative to traditional software rehosting

This paper describes one alternative to rehosting TPS software to newer computer platforms. It describes the solution that Southwest Research Institute (SwRI) used to solve a problem with re-engineering legacy software into a modern object-oriented language. The advantages gained by this method are more advanced instruction to the operator (such as pictures and movies), flexible reporting scheme to diagnose system problems, and ease of software maintenance. This solution uses commercially available products including National Instruments/spl trade/ TestStand/spl trade/ and LabVIEW/spl trade/ and Microsoft/spl reg/ Visual Basic/spl reg/. The system is a four-tiered architecture to drive all test execution. The user interface is written in Visual Basic and allows the user to interact with the test execution when needed. This user interface in turn calls tests that are written in TestStand, and finally the individual tests call driver functions written in LabVIEW. A database serves as a repository for all test results, displays, and test limits. The use of this database allows for easy querying of measurement data to analyze trends in failures that help diagnose specific problems. By using this database, all test limits and test displays are contained in one central location that enables engineers to change these displays and limits on the fly without needing to change or even understand any test code. One other benefit of this data containment is that all Government classified data is separated out of the code and stored as one file, instead of in various locations as it was in the original source code.     

Model-based robustness testing for avionics-embedded software

Robustness testing for safety-critical embedded software is still a challenge in its nascent stages. In this paper, we propose a practical methodology and implement an environment by employing model-based robustness testing for embedded software systems. It is a system-level black-box testing approach in which the fault behaviors of embedded software is triggered with the aid of modelbased fault injection by the support of an executable model-driven hardware-in-loop (HIL) testing environment. The prototype implementation of the robustness testing environment based on the proposed approach is experimentally discussed and illustrated by industrial case studies based on several avionics-embedded software systems. The results show that our proposed and implemented robustness testing method and environment are effective to find more bugs, and reduce burdens of testing engineers to enhance efficiency of testing tasks, especially for testing complex embedded systems.     

向多元化发展的空空导弹

随着战术技术性能的不断改进,空空导弹在未来战争中发挥的作用也更趋于多元化.多用途空空导弹既可以完成视距内空战任务,也可以完成超视距空战任务;既可以进行空对空作战,也可以稍加改进执行空对地作战和地对空作战任务,从而提高了武器效能,也大大简化了地面支援和后勤保障要求.     

Developing better artificial bones

Researchers at the Center for Commercial Applications of Combustion in Space at the Colorado School of Mines are preparing the Space-DRUMS (Dynamically Responding Ultrasonic Matrix Systems) materials processing facility for transport to the International Space Station. The Space-DRUMS uses acoustic pressure beams to maintain the position of a suspended liquid or solid. Space-DRUMS will be used to extend experiments with tricalcium phosphate in the development of artificial bone material.     

面向人机交互式软件的测试模型建模方法

从测试用例自动生成和自动执行的角度来探讨如何对人机交互软件建立测试模型。采用UML活动图模型来描述软件的人机交互过程。为了能够从活动图模型中生成一组确定的可执行的测试用例，给出了一组规则来细化基于活动图的测试模型所表达的语义，同时也对活动图做了一些扩展，以支持基于模型的测试用例自动生成及其自动执行。给出的建模方法，能够减少某些冗余的测试用例。