Time Delay in Rectification of Faults in Software Projects

Software reliability models, such as the Basic (i.e., Exponential) Model and the Logarithmic Poisson Model, make the idealizing assumption that when a failure occurs during a program run, the corresponding fault in the program code is corrected without any loss of time. In practice, it takes time to rectify a fault. This is perhaps one reason why, when the cumulative number of faults is computed using such a model and plotted against time, the fit with observed failure data is often not very close. In this paper, we show how the average delay to rectify a fault can be incorporated as a parameter in the Basic Model, changing the defining differential equation to a differential- difference equation. When this is solved, the time delay for which the fit with observed data is closest can be found. The delay need not be constant during the course of testing, but can change slowly with time, giving a yet closer fit. The pattern of variation during testing of the delay with time can be related both to the learning acquired by the testing team and to the difficulty level of the faults that remain to be discovered in the package. This is likely to prove useful to managers of software projects in the deployment of staff

RICIS Symposium 1992: Mission and Safety Critical Systems Research and Applications

This conference deals with computer systems which control systems whose failure to operate correctly could produce the loss of life and or property, mission and safety critical systems. Topics covered are: the work of standards groups, computer systems design and architecture, software reliability, process control systems, knowledge based expert systems, and computer and telecommunication protocols

An Examination of Significant Issues in Naval Maintenance

AbstractThis paper summarises qualitative research undertaken within the “In-Service” stage of the lifecycle of Royal Navy surface ships and submarines. Whilst In-Service, Royal Navy vessels will typically cycle through three phases, i.e. Tasking, Upkeep and Regeneration. A series of semi-structured recorded interviews conducted with key stakeholders in each phase identifies and highlights common issues encountered whilst In-Service. Having identified common issues, e.g. risk, obsolescence, manpower availability, etc. additional interviews were undertaken to triangulate the results with other safety critical companies operating and maintaining complex systems, i.e. a power company operating an advanced gas-cooled nuclear reactor, rail infrastructure and Europe's largest regional airline

System-level design and RF front-end implementation for a 3-10ghz multiband-ofdm ultrawideband receiver and built-in testing techniques for analog and rf integrated circuits

This work consists of two main parts: a) Design of a 3-10GHz UltraWideBand (UWB) Receiver and b) Built-In Testing Techniques (BIT) for Analog and RF circuits. The MultiBand OFDM (MB-OFDM) proposal for UWB communications has received significant attention for the implementation of very high data rate (up to 480Mb/s) wireless devices. A wideband LNA with a tunable notch filter, a downconversion quadrature mixer, and the overall radio system-level design are proposed for an 11-band 3.4-10.3GHz direct conversion receiver for MB-OFDM UWB implemented in a 0.25mm BiCMOS process. The packaged IC includes an RF front-end with interference rejection at 5.25GHz, a frequency synthesizer generating 11 carrier tones in quadrature with fast hopping, and a linear phase baseband section with 42dB of gain programmability. The receiver IC mounted on a FR-4 substrate provides a maximum gain of 67-78dB and NF of 5-10dB across all bands while consuming 114mA from a 2.5V supply. Two BIT techniques for analog and RF circuits are developed. The goal is to reduce the test cost by reducing the use of analog instrumentation. An integrated frequency response characterization system with a digital interface is proposed to test the magnitude and phase responses at different nodes of an analog circuit. A complete prototype in CMOS 0.35mm technology employs only 0.3mm2 of area. Its operation is demonstrated by performing frequency response measurements in a range of 1 to 130MHz on 2 analog filters integrated on the same chip. A very compact CMOS RF RMS Detector and a methodology for its use in the built-in measurement of the gain and 1dB compression point of RF circuits are proposed to address the problem of on-chip testing at RF frequencies. The proposed device generates a DC voltage proportional to the RMS voltage amplitude of an RF signal. A design in CMOS 0.35mm technology presents and input capacitance <15fF and occupies and area of 0.03mm2. The application of these two techniques in combination with a loop-back test architecture significantly enhances the testability of a wireless transceiver system

The characteristics of railway service disruption: implications for disruption management

Rail disruption management is central to operational continuity and customer satisfaction. Disruption is not a unitary phenomenon - it varies by time, cause, location and complexity of coordination. Effective, user-centred technology for rail disruption must reflect this variety. A repertory grid study was conducted to elicit disruption characteristics. Construct elicitation with a group of experts (n=7) captured 26 characteristics relevant to rail disruption. A larger group of operational staff (n=28) rated 10 types of rail incident against the 26 characteristics. The results revealed distinctions such as business impact and public perception, and the importance of management of the disruption over initial detection. There were clear differences between those events that stop the traffic, as opposed to those that only slow the traffic. The results also demonstrate the utility of repertory grid for capturing the characteristics of complex work domains

Computer Science and Technology Series : XV Argentine Congress of Computer Science. Selected papers

CACIC'09 was the fifteenth Congress in the CACIC series. It was organized by the School of Engineering of the National University of Jujuy. The Congress included 9 Workshops with 130 accepted papers, 1 main Conference, 4 invited tutorials, different meetings related with Computer Science Education (Professors, PhD students, Curricula) and an International School with 5 courses. CACIC 2009 was organized following the traditional Congress format, with 9 Workshops covering a diversity of dimensions of Computer Science Research. Each topic was supervised by a committee of three chairs of different Universities. The call for papers attracted a total of 267 submissions. An average of 2.7 review reports were collected for each paper, for a grand total of 720 review reports that involved about 300 different reviewers. A total of 130 full papers were accepted and 20 of them were selected for this book.Red de Universidades con Carreras en Informática (RedUNCI

The role of the supply chain in the elimination and reduction of construction rework and defects: an action research approach

Since 2007, Ireland has suffered a circa 80% reduction in construction output. This has resulted in bankruptcy, unemployment and bad debt. Contractors have attached greater emphasis to production efficiency and cost reduction as a means of survival. An Action Research (AR) strategy was used in this research to improve processes adopted by a SME contractor for the control of defects in its supply chain. It is conservatively estimated that rework, typically accounts for, circa 5% of total project costs. Rework is wasteful and presents an obvious target for improvement. The research reported here concerns the (first) diagnosing stage of the AR cycle only, involving: observation of fieldwork, analysis of contract documents, and semi-structured interviews with supply chain members. The results indicate potential for supply chain participants to identify root causes of defects and propose solutions, having regard to best practice to avoid re-occurrence. A lack of collaborative forums to contribute to production improvement was identified. Additionally the processes, used to collect, manage and disseminate data were unstructured and uncoordinated, indicating scope for developing more efficient methods. The research indicates good understanding of the potential benefits for supply chain collaboration but suggests that the tools and knowledge to collaborate are currently lacking in the SME sector

Detection of mine roof failure using inexpensive LiDAR technology

Slope, Roof, and mine wall stability problems are some of the main reasons for deaths at U.S. surface or underground mining. The safety instruments were not enough to prevent that failure or even predict it before it occurs. However, the cost of such a tool that can be helpful in detecting roof failures is very high and not reachable in most instances. The present study investigates the feasibility of using the M16 Leddar Evaluation Kit to detect the roof failure in mines. The M16 Leddar Evaluation kit cost is between 300$-800$, so it is the reachable price if it provides the required safety in mines. In fact, the underground mines have many openings, so the needs for instruments that can be distributed in all tunnels and safe all workers are urgent. The Leica Scan Station P40-3D Laser Scanner costs $123915.00, so in mine industry, it is not worthy to establish the mining with such high cost like that. Buying one unit of the Leica ScanStation P40-3D Laser Scanner to provide the safety and minimize the expenses in the mining industry is not a practical idea which is providing safety to some of the workers in one tunnel spot and neglect the others. Steel movement plate has been built and attached to a linear actuator that can move with a resolution around 0.00375 mm per step and stroke 50 mm in order to simulate the roof failures in mines. It is not possible to try the M16 in real mine due to the time limits and absence of not unstable mines locally, besides the intention that the author has to start with an office environment. The M16 Leddar Evaluation kit is aimed directly to movement plate and collecting the deformation derived by the actuator. The results collected has many of anomalies and irregular data that can be eliminated by doing some of the statistical identification of outliers. The results show that the M16 Leddar evaluation kit is capable of detecting the movement plate profile with a precision between 0.1 mm and 3 mm per integration period --Abstract, page iii