Implicit a posteriori error estimators are developed for elliptic boundary value problems. Local problems are formulated for the error and the corresponding Neumann type boundary conditions are approximated using a new family of gradient averaging procedure. The convergence properties of the implicit error estimator are discussed independently from that of the residual type error estimators, wh...

The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Summary: Techniques developed for hardware reliability and safety do not work on software-intensive systems; software does not satisfy the assumptions underlying these techniques. The new problems and why the current approaches are not effective for complex, software-intensive ...

Industry is increasingly adopting software and system safety standards that mandate the use of hazard logs in the development and operation of safety critical systems. Hazard logs are used to record and track the results of hazard analysis and risk assessment throughout the lifecycle of the system. Even relatively simple systems give rise to large amounts of information and the need for tools t...

Background and Objectives: Patient Safety Culture is increasingly recognized as an essential driver of patient safety. To establish patient safety culture, firstly the current status of the construct should be assessed. Valid assessment of patient safety culture is contingent on the availability of appropriate measurement tools. Hospital Survey on Patient Safety Culture (HSOPS) developed by th...

Implicit a posteriori error estimators are developed for elliptic boundary value problems. Local problems are formulated for the error and the corresponding Neumann type boundary conditions are approximated using a new family of gradient averaging procedure. The convergence properties of the implicit error estimator are discussed independently from that of the residual type error estimators, wh...

We consider the problem of allocating production capacity among multiple items, assuming that a fixed proportion of overall capacity can be dedicated exclusively to the production of each item. Given a capacity allocation, production of each item follows a base-stock policy, i.e., each demand triggers a replenishment order to restore safety stocks to target levels. We present procedures for cho...

We show that the norm of the commutator defines “almost a metric” on the quotient space of commuting matrices, in the sense that it is a semi-metric satisfying the triangle inequality asymptotically for large matrices drawn from a “good” distribution. We provide theoretical analysis of this results for several distributions of matrices, and show numerical experiments confirming this observation.

FUNCTION Mass/energy flow and balance GENERAL FUNCTION Flow and storage of heat, etc. PHYSICAL FUNCTION States of components what? what? what? what? what?

In this note we consider a fluid flow, single part-type, single unreliable machine production system with a bounded backlog/inventory space. We prove that, as in the unbounded case, the problem of minimizing an infinite horizon average demand loss/backlog/surplus cost is solved by a hedging point policy. An implicit equation is given, whose structure easily allows to numerically evaluate the op...