This article surveys the application of gamma processes in maintenance. Since the introduction of the gamma process in the area of reliability in 1975, it has been increasingly used to model stochastic deterioration for optimising maintenance. Because gamma processes are well suited for modelling the temporal variability of deterioration, they have proven to be useful in determining optimal ins...

In this study, we demonstrate near-0.1 V minimum operating voltage of a low-variability Silicon on Thin Buried Oxide (SOTB) process for one million logic gates on silicon. Low process variability is required to obtain higher energy efficiency during ultra-low-voltage operation with steeper subthreshold slope transistors. In this study, we verify the decrease in operating voltage of logic circui...

Excessive variation in a manufacturing process is one of the major causes of a high defect rate and poor product quality. Therefore, quick detection of changes, especially increases in process variability, is essential for quality control. In modern manufacturing environments, most of the quality characteristics that have to be closely monitored are multivariate by the nature of the application...

Nonparametric control charts are presented in order to figure out the problem of detecting changes in the process median (or mean)‎, ‎or changes in the variability process where there is limited knowledge regarding the underlying process‎. ‎When observations are reported imprecise‎, ‎then it is impossible to use classical nonparametric control charts‎. ‎This paper is devoted to the problem of c...

The heavy metal concentration of sewage sludge increased during composting for cadmium, chromium, lead and zinc and decreased for copper and nickel. Cadmium and lead were the most variable of the metals, copper and zinc the least. Variability within a batch was small (variation of 4-12%). Variability attributable to batch-to-batch differences was generally larger (variation of 4-37%). The varia...

With the increasing size and complexity of software systems also the amount of software variability grows. In this paper we present decision models as a means of dealing with software variability and views on decision models that are supposed to make the large amount of variability manageable. Also some mechanisms for supporting the process of decision modelling and resolving decision models ar...

Business Process Models are a relevant input for the development of information systems. Since processes are performed in increasingly dynamic business environments, the processes are required to be flexible and dynamic as well, adapting to environmental changes. Thus, it is essential to properly represent variability in Business Process Models. Moreover, in order to allow for adaptive and auto...

Statistical techniques are effective and powerful means of quantifying the variability of processes, analyzing this variability with reference to product requirements, and eliminating this variability in product manufacturing. Many process capability indices have been effectively and widely used to determine whether the quality of a process meets preset targets. However, conventional process ca...

Improving technologies create a “buy or wait?” dilemma. In this paper, we consider repeat purchases when the consumer faces an infinite stream of new technologies. We develop a probabilistic model and focus on the role of “more variability” on the process of technological innovation. Similar to real options models, we find that variability in the technological process increases value for the co...

Vacuum-assisted resin transfer molding (VARTM) has the potential advantages of relatively low cost processing with sufficiently high volume fractions of reinforcement and can be readily applied to large-scale structures. However, for many aircraft applications, VARTM does not currently provide sufficient repeatability or control of variability. Such variability is commonly observed when process...