With the evolution of technology, the maintenance of sophisticated systems is of concern for system engineers and system designers. The maintenance cost of the system depends in general on the replacement and repair policies. The system replacement may be in a strictly periodic fashion or on a random basis depending upon the maintenance policy. At failure, the repair of the system may be perfor...

In this paper we study the steady state availability of main k-out-of-n: F and secondary subsystems having general repair time distribution. When more than k units of main subsystem fail, then the main subsystem shuts off the secondary subsystem. The life time distributions of the main units and that of secondary subsystem are exponentially distributed. A repair facility having single repairman...

celiac artery aneurysm is a rare visceral aneurysm, comparising only 4 % of them. in this article, an innovative surgical method is presented for the treatment o f such aneurysms. a 53 year old female referred to our center with epigastric pain and a mass in the region, which was diagnosed as a case of celiac artery aneurysm by using different imaging techniques. during the operation, according...

generally, the failure rate and the repair time of system components are constant parameters in reliability assessment of electric distribution systems. a failure of component is resulted from failing in the operation or overloading. in addition, there exist cases where, the repair times of components are small and tolerable from customer point of view. thus, tolerable repair times may be overl...

treacher collin’s syndrome (tcs) is a rare inherited condition characterized by bilateral and symmetric abnormalities of structures within the first and second bronchial arches. patients with tcs present a serious problem to anesthetists maintaining their airway as upper airway obstruction and difficult tracheal intubation due to severe facial deformity. because of retrognathia, airway manageme...

introduction: pilonidal sinus is a common disease in sacrococcygeal area, which mostly caught young people and cause disability, which needs complete rest at home and taking off from work. although the surgical treatment of this problem goes back to the last century, still optimal treatment is a controversy. recent studies have raised different surgical approaches, so that there is no general a...

This paper deals with bi-level control policy and queuing analysis of a machine repair problem. The model is developed by incorporating mixed standbys (cold and warm), reneging, set up and vacation time. The repair facility consists of two heterogeneous repairmen in the system. The life and repair time of the failed units and also their set up times are assumed to be exponentially distributed. ...

The machine repair problem with spares and additional repairman is analyzed. The interfailure and repair times of the units are general identical and independently distributed. The failure and repair rates are assumed to be state dependent. Using diffusion approximation technique, we obtain the queue size distribution under steady state. The average number of failed units, average number of ope...