Prediction intervals for reliability growth models with small sample sizes

Engineers and practitioners contribute to society through their ability to apply basic scientific principles to real problems in an effective and efficient manner. They must collect data to test their products every day as part of the design and testing process and also after the product or process has been rolled out to monitor its effectiveness. Model building, data collection, data analysis and data interpretation form the core of sound engineering practice.After the data has been gathered the engineer must be able to sift them and interpret them correctly so that meaning can be exposed from a mass of undifferentiated numbers or facts. To do this he or she must be familiar with the fundamental concepts of correlation, uncertainty, variability and risk in the face of uncertainty. In today's global and highly competitive environment, continuous improvement in the processes and products of any field of engineering is essential for survival. Many organisations have shown that the first step to continuous improvement is to integrate the widespread use of statistics and basic data analysis into the manufacturing development process as well as into the day-to-day business decisions taken in regard to engineering processes.The Springer Handbook of Engineering Statistics gathers together the full range of statistical techniques required by engineers from all fields to gain sensible statistical feedback on how their processes or products are functioning and to give them realistic predictions of how these could be improved

A Model for Quality Optimization in Software Design Processes

The main objective of software engineers is to design and implement systems that implement all functional and non-functional requirements. Unfortunately, it is very difficult or even generally impossible to deliver a software system that satisfies all the requirements. Even more seriously, failures in fulfilling requirements are generally detected after the realization of software systems. This is because design decisions are mostly taken based on estimations, which can turn out to be wrong at a later stage in the design process. Switching to different design alternatives at a later stage can be very difficult since this may demand drastic changes in design and also may increase project time and costs. In this paper a model is proposed for modeling and tracing design processes with respect to the selected design alternatives. Based on the model, two algorithmic definitions of design strategies are given, which enable software engineers to optimize design decisions with respect to quality and resource constraints

Inverse-Compton Emission from Clusters of Galaxies: Predictions for ASTRO-H

The intra-cluster medium of several galaxy clusters hosts large-scale regions of diffuse synchrotron radio emission, known as radio halos and relics, which demonstrate the presence of magnetic fields and relativistic electrons in clusters. These relativistic electrons should also emit X-rays through inverse-Compton scattering off of cosmic microwave background photons. The detection of such a non-thermal X-ray component, together with the radio measurement, would permit to clearly separate the magnetic field from the relativistic electron distribution as the inverse-Compton emission is independent from the magnetic field in the cluster. However, non-thermal X-rays have not been conclusively detected from any cluster of galaxies so far. In this paper, for the first time, we model the synchrotron and inverse-Compton emission of all clusters hosting radio halos and relics for which the spectral index can be determined. We provide constraints on the volume-average magnetic field by comparing with current X-ray measurements. We then estimate the maximum volume-average magnetic field that will allow the detection of inverse-Compton hard X-rays by the ASTRO-H satellite. We found that several clusters are good targets for ASTRO-H to detect their inverse-Compton emission, in particular that corresponding to radio relics, and propose a list of promising targets for which ASTRO-H can test $\ge1$~$\mu$G magnetic fields. We conclude that future hard X-ray observations by the already-operating NuSTAR and the soon-to-be-launched ASTRO-H definitely have the potential to shed light on the long-sought non-thermal hard-X-ray emission in clusters of galaxies.Comment: 28 pages, 5 figures, 9 Tables. Accepted by A&

Predicting Cost/Reliability/Maintainability of Advanced General Aviation Avionics Equipment

A methodology is provided for assisting NASA in estimating the cost, reliability, and maintenance (CRM) requirements for general avionics equipment operating in the 1980's. Practical problems of predicting these factors are examined. The usefulness and short comings of different approaches for modeling coast and reliability estimates are discussed together with special problems caused by the lack of historical data on the cost of maintaining general aviation avionics. Suggestions are offered on how NASA might proceed in assessing cost reliability CRM implications in the absence of reliable generalized predictive models

The Human Element of Decision Making in Systems Engineers: A Focus on Optimism

Biases continue to be an important aspect of human judgment and decision making because they can lead to unfavorable outcomes. Optimism bias is one type of bias that is often overlooked because of its association with good health and positive outcomes. However, the existence of optimism bias in human judgment can be very damaging especially when it distorts a person’s view of future events. In order to better understand optimism bias we explore the benefits and downsides of optimism as well as some empirically-based origins of both optimism and pessimism. This provides a backdrop for a methodology for quantifying optimism and pessimism using the Brier score developed for calibrating weather reporters and a discussion about how sports bookies make well-calibrated decisions. Results are explored from an optimism survey given to a cohort of eighty systems engineers, which ultimately portray the degree to which optimism bias influences decision making in large projects. Further exploration of the key differences in optimism across professions helps distinguish motivational factors and characteristics of well-calibrated professions. We also present results from a calibration exercise, designed to infer if such activities can be adopted to assist systems engineering estimation. Finally, we provide prescriptive advice on how individual decision makers can better manage their optimism and become more realistic

The prospect of using LES and DES in engineering design, and the research required to get there

In this paper we try to look into the future to divine how large eddy and detached eddy simulations (LES and DES, respectively) will be used in the engineering design process about 20-30 years from now. Some key challenges specific to the engineering design process are identified, and some of the critical outstanding problems and promising research directions are discussed.Comment: accepted for publication in the Royal Society Philosophical Transactions