This paper provides an approximate analytic solution method for evaluating the performance of concurrency control protocols developed for real-time database systems (RTDBSs). Transactions processed in a RTDBS are associated with timing constraints typically in the form of deadlines. The primary consideration in developing a RTDBS concurrency control protocol is the fact that satisfaction of the...

A method is proposed to determine the phase-volume fractions in tomographic representations of two-phase systems. The method is applicable in cases where no independent mean values for the phase-characteristic property (a) are available, such as in standard X-ray computed tomography (CT) using a polychromatic source. The proposed procedure is based on ®tting a sum of three parametric expression...

A safe and deadlock free lock policy is introduced, called pre-analysis locking. Pre-analysis locking is based on an efficient geometric algorithm which inserts lock and unlock operations into the transactions. Pre-analysis locking is the first safe and deadlock free general locking policy which is not a variant of two-phase locking. It is an approach conceptually different from policies follow...

An approach to support activities in collaborative databases is proposed. This approach merges exible transaction models from collaborative environments and semantics based cor-rectness criteria. A model is rst presented which incorporates the notion of collaboration in the context of transactions. A protocol is then developed based on this model for eecient management of collaborative activiti...

This paper investigates the integrated optimization of production, distribution and inventory decisions related to supplying multiple retailers from a central production facility. A single-item uncapacitated lot-sizing problem is defined for optimizing production decisions and inventory management. The optimization of daily distribution is modeled as a traveling salesman problem or a vehicle ro...

a r t i c l e i n f o a b s t r a c t The level-set method is a popular interface tracking method in two-phase flow simulations. An often-cited reason for using it is that the method naturally handles topological changes in the interface, e.g. merging drops, due to the implicit formulation. It is also said that the interface curvature and normal vectors are easily calculated. This last point is...

The two-phase issue in the O(n) non-linear σ-model: a Monte-Carlo study Our paper [1] has motivated a comment [2] by A. Patrascioiu and E. Seiler which we reply in this note. The remarks in [2] concern three statements that the authors select from our paper: i) " The results for O(8) support the asymptotic freedom scenario ". The authors in [2] recall that at small˜β ≡ β/N the 1/N expansion is ...

Due to the unpredictability of mobile network, it is difficult to meet transaction deadlines in a mobile distributed real-time database system (MDRDTBS). We propose the idea of transaction shipping to reduce the overheads in processing a transaction over mobile network and in resolving priority inversion. We consider a distributed lock-based real-time protocol, the Distributed High Priority Two...

In this paper we derive rates of convergence for regularizations of the multidimensional two-phase Stefan problem and use the regularized problems to define backward-difference in time and C° piecewise-linear in space Galerkin approximations. We find an L2 rate of convergence of order \^ in the e-regularization and an L rate of convergence of order (h2/e + Ai/ \6F) in the Galerkin estimates whi...

To operate effectively in complex environments learning agents have to selectively ignore irrelevant details by forming useful abstractions. In this paper we outline a formulation of abstraction for reinforcement learning approaches to stochastic decision problems by extending one of the recent minimization models, known as ǫ-reduction. The technique presented here extends ǫ-reduction to SMDPs ...