In this paper, we consider retrial queueing systems with batch arrivals in which the server is subject to controllable interruptions (called vacations) and random interruptions (breakdowns). No specific assumption is taken regarding probability distributions of parametric random variables. The purpose of this work is to show effect of above mentioned parameters (in particular retrial and breakd...

A server subject to random breakdowns and repairs offers services incoming jobs whose lengths are highly variable. checkpointing policy aiming protect against possibly lengthy recovery periods is in operation. The problem of how choose a interval order optimize performance addressed by analysing general queueing model which includes breakdowns, repairs, back-ups recoveries. Exact solutions obta...

All of us agree on the benefits of computers, but we must also pay attention to the complications and problems they bring along these benefits. For instance, new physical health problems on back, hands and eyes are much discussed in the field of occupational health. Some diagnosis and treatment methods are getting standardized for computer-related problems. One more important issue is their eff...

Scintillations in solid tantalum capacitors are momentarily local breakdowns terminated by a self-healing or conversion to a high-resistive state of the manganese oxide cathode. This conversion effectively caps the defective area of the tantalum pentoxide dielectric and prevents short-circuit failures. Typically, this type of breakdown has no immediate catastrophic consequences and is often con...

When computingrecursively the members of a family of formal orthogonal polynomials, a division by zero can occur, thus producing a breakdown in the algorithm which has to be stopped. In this paper, such breakdowns are analyzed in detail and classiied. It is also showed how to avoid them in some particular cases. Applications to Pad e approximation, extrapolation methods and Lanczos method for s...

ZBIGNIEW LEYK Abstract. One of the disadvantages of Krylov subspace iterative methods is the possibility of breakdown. This occurs when it is impossible to get the next approximation of the solution to the system of linear equations Au = f . There are two di erent situations: lucky breakdown, when we have found the solution and hard breakdown, when the next Krylov subspace cannot be generated a...