Sensitivity of reliability-growth models to operational profileerrors vs. testing accuracy [software testing]

This paper investigates: 1) the sensitivity of reliability-growth models to errors in the estimate of the operational profile (OP); and 2) the relation between this sensitivity and the testing accuracy for computer software. The investigation is based on the results of a case study in which several reliability-growth models are applied during the testing phase of a software system. The faults contained in the system are known in advance; this allows measurement of the software reliability-growth and comparison with the estimates provided by the models. Measurement and comparison are repeated for various OPs, thus giving information about the effect of a possible error in the estimate of the OP. The results show that: 1) the predictive accuracy of the models is not heavily affected by errors in the estimate of the OP; and 2) this relation depends on the accuracy with which the software system has been tested     

Why software fails [software failure]

Most IT experts agree that software failures occur far more often than they should despite the fact that, for the most part, they are predictable and avoidable. It is unfortunate that most organizations don't see preventing failure as an urgent matter, even though that view risks harming the organization and maybe even destroying it. Because software failure has tremendous implications for business and society, it is important to understand why this attitude persists.     

Tools for schools [mathematical software packages]

The latest math packages for engineering education offer: programming through icons; collaboration over the Internet; electronic textbooks; and free courseware on the Web. Mathematical software tools can be divided into two groups: programs that chiefly perform symbolic manipulations (also called computer algebra programs for their ability to find exact solutions to analytical expressions) and programs used primarily for large numerical calculations. But the line between these tools is blurring, for some leading vendors now produce packages that include both numerical and symbolic capabilities. The author discusses both types of program and describes some of the features and functions of the programs     

The exterminators [software bugs]

This paper describes a sound methodology developed at Praxis High Integrity Systems for detecting and exterminating bugs during all stages of a software project. To develop software, the London-based software house uses mathematically based techniques, known as formal methods, which require that programmers begin their work not by writing code but rather by stringing together special symbols that represent the program's logic. Like a mathematical theorem, these symbol strings can be checked to verify that they form logically correct statements. Once the programmer has checked that the program doesn't have logical flaws, it's a relatively simple matter to convert those symbols into programming code. With an average of less than one error in every 10,000 lines of delivered code, Praxis claims a bug rate that is at least 50 times better than the industry standard.     

Crashproof codes [flight software]

Boeing Co. and NASA have joined forces for the Active Aeroelastic Wing (AAW) Project to test the way a modified F/A-18 strike fighter uses its wings. The AAW was designed to be flexible enough to be twisted on demand in flight and it could herald nothing less than a revolution in aviation. The twisting can be used to control the plane's roll, reducing and ultimately eliminating the need for ailerons and flaps and their associated hardware. AAW-equipped planes would result to increased fuel efficiency and improved maneuverability, able to execute sharper turns at higher speeds. A special flight software was developed to keep track of the plane's speed, altitude, and attitude while monitoring the pilot's controls for commands. Based on a set of rules known as control laws, the software must then translate any commands from the pilot into movements of the aircraft's various control surfaces such as the rudders or, most significantly, the flaps that flex the AAWs. Despite its complex and critical job, the flight software is compact, consisting of only about 13,000 lines of source code written in the Ada language.     

Semantic failure [of software]

The author offers the opinion that the adoption of the terminology of hardware reliability in the context of software was a terrible, probably unavoidable, and perhaps even necessary, mistake: terrible-because the words cannot have the same meanings in both contexts; and unavoidable-because today there are few systems whose reliability can be assessed without dealing with both     

Collaboration nation [group software]

As group software assumes a major role in the workplace, will engineers stop talking to each other? Communication is the essence of collaboration, and increasingly communication about semiconductor design is happening over the Internet not only through e-mail and threaded discussion boards, but also through specially designed Web collaboration software that lets engineers work on parts of the same chip simultaneously, whether they are down the hall or across the world. The increasing use of collaborative software has raised concerns that the engineering workplace would suffer from diminished human contact, and that engineers would be transformed into zombie-like automatons, addicted to their workstations. That hasn't happened; workplace experts say that engineers rely as much as ever on face-to-face interactions.     

Open-source media [mobile multimedia software]

Multimedia is opening up a vast new frontier for software companies, thanks to the rapid growth of broadband connections to desktop computers and ever more capable cell-phones and wireless PDAs. RealNetworks is about to find out if its open-source gambit is going to pay off, as the first wave of Helix-powered hardware reaches the market. So far, only a handful of such devices have been released, including the Sony Vega television in Japan and the palmOne Treo 650 smart phone in the United States. No doubt other software vendors are watching closely; an open-source model that compels all developers to assign copyright back to the "mother ship" could soon become the preferred way to nurture communities of developers.     

Total recall [life recording software]

This paper describes a Microsoft research initiative that focuses on memory augmentation. The research is primarily based on the MyLifeBits Project of Microsoft researcher, Gordon Bell, who, for two years, collected real life data using sensors and a still camera, called SenseCam, with the aim of developing a improved means of information retrieval. With the MyLifeBits software, the SenseCam, and the low cost of memory of all kinds, the rebirth of the PC into a personal mainframe can be realized.     

The African hacker [software development]

This paper narrates the success story of Hermann Chinery-Hesse, chief of Soft Tribe Ltd. located at Ghana, West Africa. Chinery-Hesse has made a small fortune writing software, working as a systems architect, and selling computer code to hundreds of businesses in his country. Through Soft, Chinery-Hesse has also been providing training programs for the country's growing population of full-time programmers. His dream remains to expand software in Ghana, to make more money and to show the world that despite the often depressing headlines about poverty and mayhem in Africa, there are opportunities for technical talent.     

Measurements column [antenna testing]

The alignment of the mechanical axes of a compact range test positioner to the compact range wavefront is addressed. Reflection measurements are used to calibrate the range and to determine the gain of antennas. It is shown that the circular flat plate and the vertical wire are accurate electrical alignment tools for the field direction and the polarization vector. With the plate, it was possible to align the field horizontally and in the horizontal plane within 4 arc s. The polarization vector could be aligned within 7 arc s. Furthermore, the plate can be used to make an error estimate of the center section of the quiet zone, over a wide angular range, and can be used as a gain standard     

A conservative theory for long-term reliability-growth prediction[of software]

This paper describes a different approach to software reliability growth modeling which enables long-term predictions. Using relatively common assumptions, it is shown that the average value of the failure rate of the program, after a particular use-time, t, is bounded by N/(e·t), where N is the initial number of faults. This is conservative since it places a worst-case bound on the reliability rather than making a best estimate. The predictions might be relatively insensitive to assumption violations over the longer term. The theory offers the potential for making long-term software reliability growth predictions based solely on prior estimates of the number of residual faults. The predicted bound appears to agree with a wide range of industrial and experimental reliability data. Less pessimistic results can be obtained if additional assumptions are made about the failure rate distribution of faults     

An inspector calls [nondestructive testing]

Composite laminate structures offer many advantages compared with their conventional metal counterparts, but defects can be much harder to detect. In this paper, the author describes how neural networks provide the key to a new, intelligent technique for nondestructive testing     

In-circuit test fixture [PCB testing]

Deficiencies in the conventional in-circuit fixture are presented. A novel fixture is described, and quantitative comparisons are presented. Crosstalk is decreased by 60 dB, and transmission-line matching is possible