negligible

Establishing a Vibration Threshold Value, Which Ensures a Negligible False Alarm Rate for Each Gear in CH-53 Aircraft Using the Operational Data
$25.95
This is a NAVAL POSTGRADUATE SCHOOL MONTEREY CA report procured by the Pentagon and made available for public release. It has been reproduced in the best form available to the Pentagon. It is not spiral-bound, but rather assembled with Velobinding in a soft, white linen cover. The Storming Media report number is A465024. The abstract provided by the Pentagon follows: Rotating machinery such as gears plays an important role in control of an aircraft. The condition of this machinery is a key ingredient to both platform safety and mission success, especially in military operations. The purpose of the thesis research is to establish a vibration threshold level for each particular gear in CH-53 aircraft such that, while minimizing in-flight risk, a negligible false alarm rate is obtained. This study uses Box-Jenkins time series modeling (ARMA) with regression, Mahalanobis distance metrics, goodness-of-fit tests and the Bonferroni correction to explore the structure of the historical acquisition datasets for particular gear type and aircraft, to set vibration threshold values for "Warning" and "Alarm" situations. Although 28 datasets could not be modeled because of small sample sizes, the other 224 data sets were successfully modeled using ARMA with regression modeling technique. The Mahalanobis distance metric was then used to set a threshold value of "Warning" and "Alarm" for each gear type. These threshold values were then checked with new data and 200 outliers for "Warning" and 69 outliers for "Alarm" were detected. These outliers might be evaluated as false alarms.

Optimal management of cross-trained workers in services with negligible switching costs [An article from: European Journal of Operational Research]
$5.95
This digital document is a journal article from European Journal of Operational Research, published by Elsevier in . The article is delivered in HTML format and is available in your Amazon.com Media Library immediately after purchase. You can view it with any web browser.

Description:
In this paper we consider a retail service facility with cross-trained workers who can switch between the front room and the back room depending on the size of the queue in the front room. Two problems are presented. In the first problem, given a fixed number of cross-trained workers the objective is to find optimal switching points so that the expected customer waiting time is minimized subject to a back room service level constraint. In the second problem the number of workers is also a decision variable and the objective is to minimize it subject to both front room and back room service level constraints. The paper includes an analysis of the model and based on it several heuristics are suggested. Computational analysis with the recommended heuristics is presented and comparison to optimal solutions derived by complete enumeration shows excellent results.

Engineered Negligible Senescence
$0.99