A statistical index of growth condition in an aquaculture experiment

A simple statistical index, for evaluating the condition of growth in an aquaculture experiment and indicating the extent of effect of any plausible rival hypothesis, is presented.

A method for identifying scope and assumptions in developing and selecting methods and tools

This technical report describes a practical method consisting of a checklist and a supporting techniques for those planning or just starting to develop or select design tools and methods. The method helps to summarize and illustrate the envisaged tool or method by identifying its scope and the underlying assumptions. The resulting tool or method description clarifies the problem that is addressed, the approach and the possible implications, and can thus be used by a variety of people involved in assessing a tool or method in an early stage. For the developers themselves the method reveals how realistic the envisaged method or tool is, and whether the scope has to be narrowed.

Statistical gear health analysis which is robust to fluctuating loads and operating speeds

Condition-based maintenance is concerned with the collection and interpretation of data to support maintenance decisions. The non-intrusive nature of vibration data enables the monitoring of enclosed systems such as gearboxes. It remains a significant challenge to analyze vibration data that are generated under fluctuating operating conditions. This is especially true for situations where relatively little prior knowledge regarding the specific gearbox is available. It is therefore investigated how an adaptive time series model, which is based on Bayesian model selection, may be used to remove the non-fault related components in the structural response of a gear assembly to obtain a residual signal which is robust to fluctuating operating conditions. A statistical framework is subsequently proposed which may be used to interpret the structure of the residual signal in order to facilitate an intuitive understanding of the condition of the gear system. The proposed methodology is investigated on both simulated and experimental data from a single stage gearbox. © 2011 Elsevier Ltd. All rights reserved.