T hree patients with calcific aortic valvular disease associated with complete heart block underwent total aortic valvular replacement at Deborah Hospital. One patient had concomitant epicardial implantation of a “synchronous” ( atrial triggered) pacemaker, and two patients had pacemakers implanted prior to aortic valve surgery. Although these patients had practically identical lesions, their s...

Caching frequently accessed data items on the client side is an effective technique to improve the system performance in mobile environment. Due to cache size limitations, the choice of cache replacement techniques used to find a suitable subset of items for eviction from cache becomes important. In this paper, we propose a new cost function based cache replacement policy, Predicted Region Base...

To optimize the multimedia proxy server effectively, this paper proposes a gain-based cache replacement policy by using the multimedia proxy server gain model. The performance of the proposed gain-based policy is evaluated by simulation experiments.

The parallel machine replacement problem consists of finding a minimum cost replacement policy for a finite population of economically interdependent machines. In this paper, we formulate a stochastic version of the problem and analyze the structure of optimal policies under general classes of replacement cost functions. We prove that for problems with arbitrary cost functions, there can be opt...

In the literature on replacement/maintenance policies for systems of stochastically failing machines, it is generally assumed that the failure time parameters are known and the objective is to find a replacement policy that minimizes expected cost per unit of time. In practice, however, the variability of costs can be an important consideration. In addition, most managers would want to adapt to...

Condition-based maintenance is rapidly gaining favor as a way to prevent the failures of capital-intensive assets and to maintain them in good operating condition with minimum cost. A valuable and increasingly prevalent way to incorporate condition information into risk estimation is by the proportional hazards model (PHM), which explicitly includes both the age and the condition information in...

Caching is a key technique in mobile computing environment for improving the data retrieval performance. Due to cache size limitations, cache replacement algorithms are used to find a suitable subset of items for eviction from the cache. It has been observed that cached items in a client are related to each other and therefore replacement of a data item which is highly associated may lead to se...