We give improved approximation algorithms for a variety of latency minimization problems. In particular, we give a 3.591-approximation to the minimum latency problem, improving on previous algorithms by a multiplicative factor of 2. Our techniques also give similar improvements for related problems like k-traveling repairmen and its multiple depot variant. We also observe that standard techniqu...

A field study of 89 refrigerator repairmen was carried out to ascertain whether occupational exposure to fluorocarbons induces cardiac arrhythmia. The concentrations of fluorocarbons in the breathing zones and the heart activity were recorded simultaneously. Most cooling systems contained FC 12 or FC 22. The highest level recorded in one minute was 14,000 ppm and the highest time weighted level...

In this paper authors have considered a system having three units A, B1 and B2. A is controlled by a controller and B1 and B2 are independent. Two repairmen are involved in repair of the system. One of the repairmen (the first) is the foreman (boss) and the other an assistant (apprentice). Whenever any unit fails, repair is undertaken by boss. If the boss is busy in repairing and at the same ti...

Heterogeneous travelling repairmen problem with time windows (hetTRPTW) is customer oriented problem with large possibilities for practical applications in logistics area. Models and algorithms developed for solving one problem with a cumulative objective function may be, with a little effort, transformed for solving similar problem with a cumulative function. In that sense, aim of this paper i...

This paper deals with machine repair problem with balking and reneging. There is provision of mixed standby (warm and cold) components to replace the failed machines. The lifetime and repair time are assumed to have exponential distribution. Birth-death technique is suggested to obtain the queue size distribution in explicit form. A repair facility of C permanent repairmen is facilitated to rep...

We analyse the reliability (survival function) of a duplex system characterized by hot standby and sustained an auxiliary unit in cold standby. The entire is attended two heterogeneous repairmen. Our methodology based on theory sectionally holomorphic functions combined with notion dual transforms. Finally, we also study total occupational time repairman responsible for repair failed priority d...

We consider a two-unit cold standby system attended by two repairmen and subjected to a priority rule. In order to describe the random behavior of the twin system, we employ a stochastic process endowed with state probability functions satisfying coupled Hokstadtype differential equations. An explicit evaluation of the exact solution is in general quite intricate. Therefore, we propose a numeri...

In this study, stochastic modelling and analysis of a repairable 2-out-of-4 system is presented. The system under study is exposed to four types of failures and is attended by four repairmen. The failure and repair time are assumed exponentially distributed. Explicit expressions for mean time to system failure (MTSF), the steady-state availability, and busy period of repairman and profit functi...

The maintenance of large-scale systems is an important issue for logistics support planning. In this paper, we developed a Logistical Remote Association Repair Framework (LRARF) to aid repairmen in keeping the system available. LRARF includes four subsystems: smart mobile phones, a Database Management System (DBMS), a Maintenance Support Center (MSC) and wireless networks. The repairman uses sm...