A Simple Empirical Method for Predicting Library Circulations
Recent work has demonstrated that stochastic models, incorporating a time parameter, have great potential value for library management in predicting future use of library materials, particularly in the presence of ageing of materials. In this paper a simple empirical Bayes method is presented which avoids the analytic complexity of earlier models and which may therefore be more attractive to the library manager. In particular, the ‘prediction profile’ is advocated as a useful additon to the manager's toolbox.
Predicting Book Use for Oo-site Storage
We explore various methods for predicting library book use. Accurate prediction is invaluable when choosing titles to be stored in an o -site location. Previous researchers in this area concluded that previous use information provides by far the most reliable predictor of future use. Because of the computerization of library data, it is now possible not only to reproduce these earlier experiments with a more substantial data set, but also to compare their algorithms with more sophisticated decision methods. We have found that while previous use is indeed an excellent predictor of future use, it can be improved upon by combining previous use information with bibliographic information in a technique that can be customized for individual collections. This has immediate application for libraries that are short on storage space and wish to identify low-demand titles to move to remote storage. For instance, simulations show that the best prediction method we develop, when used as the o -site storage selection method for the Harvard College Library, would have generated only a fth as many o -site accesses as compared to a method based on previous use. 1
Effects of reservoir volume on performance of pulse tube cooler.
A pulse tube cooler has the advantages of long-life and low-vibration over conventional cryocoolers such as G-M and Stirling coolers because of the absence of moving parts at low temperature. On the other hand, the combination of a reservoir and orifice is indispensable to optimize the performance of pulse tube coolers. In order to make the pulse tube cooler compact for practical applications, the volume of reservoir should be minimized. This paper analyzes the effects of the reservoir volume on the thermodynamic performance of various components in a simple orifice and a double-inlet pulse tube cooler by combining a linearized model with a thermodynamic analysis. Expressions of entropy production for those components are presented. The results show that the reservoir volume has a significant influence on the entropy production in the various components when the reservoir to pulse tube volume ratio is smaller than about 5. The ratio is important to determine the minimum reservoir volume for a pulse tube cooler. Optimum settings for a double-inlet pulse tube cooler are also discussed.