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Carousel Storage Systems:

A carousel storage system is a series of bins or baskets fastened to carries that are connected together and revolve around a long, oval track system. The track system is similar to a trolley conveyor system. Its purpose is to position bins at a load/unload station at the end of the oval. The operation is similar to the powered overhead rack system used by dry cleaners to deliver finished garments to the front of the store. The typical operation of the storage carousel is mechanized rather than automated. The load/unload station is manned by a human worker who activates the powered carousel to deliver a desired bin to the station. One or more parts are removed from the bin, and the cycle is repeated. Carousel come in a variety of sizes, ranging between 10 and 100 ft in length of the oval. As the length of the carousel is increased, the storage density increases, but hte avarage transaction time (Storage or retrieval) decreases. Accordingly, the typical carousel size ranges perhaps between 30 and 50 ft to achieve a proper balance between these opposing factors. (S. A. Kumar, Production And Operations Management, p. 186)

Repeatability:

Repeatibility (reproducibility) error is caused by inability of a sensor to represent the same value under presumability identical consditions. The repeatability is expressed as a maximum difference between the output readings as determined by two calibrating cycles, unless otherwise specified. It is usually represented as % of FS:

(delta)r=delta/FS*100%

Possible sources of the repeatability error may be thermal noise, build up charge, material plasticit,etc.

(J. Fraden, Handbook of Nodern Sensors: Physics, Design, and Application, p.38)

Weibull Distribution:

This basic section present the Weibull distribution.The Weibull distribuiton is usefull in a great variety of applications, particularly as a model for product life. It also has been used as the distribution of strength of certain materials. It is named after Waloddi Weibull(1951), who popularized its use among engineers. One reason for its popularity is that it has a great variety of shapes. This makes it extremely flexible in fitting data, and it emprically fits many kinds of data.

It may be suitable for a "weakest link" type of product. In other words, if a unit consist of many parts, each with a failure time from the same distribution (bounded from below) and the unit fails with the first part failure, then the Weibull distribution mat be suitable for such units. For example, the life of a capacitor is thought to be determined by the weakest(shortest lived) portion of dielectric in it.,

(W. Nelson, Applied life data analysis, p. 36)