The structure of pipe networks minimizing the total energy dissipation rate is studied analytically. Among all the possible pipe networks that can be built with a given total pipe volume (or pipe lateral surface area), the network which minimizes the dissipation rate is shown to be loopless. Furthermore, such an optimal network is shown to contain at most N-2 nodes in addition to the N sources ...

In some cases the optimum is the minimum of the objective function (mathematical optimum), but in other cases the optimum is given by a technical constraint (technical optimum). The present paper shows the both types in two problems. The first problem is to find the optimum dimensions of a ring-stiffened circular cylindrical shell subject to external pressure, which minimize the structural cost...

When an elastomer imbibes a solvent and swells, a force is generated if the elastomer is constrained by a hard material. The magnitude of the force depends on the geometry of the constraint, as well as on the chemistry of the elastomer and solvent. This paper models an elastomer crosslinked on the exterior surface of a metallic tubing. The elastomer then imbibes a solvent and swells. After the ...

In this paper we consider the problem of finding the densest subset subject to co-matroid constraints. We are given a monotone supermodular set function f defined over a universe U , and the density of a subset S is defined to be f(S)/|S|. This generalizes the concept of graph density. Co-matroid constraints are the following: given matroid M a set S is feasible, iff the complement of S is inde...

Let f : 2 → R+ be a monotone submodular set function, and let (X, I) be a matroid. We consider the problem maxS∈I f(S). It is known that the greedy algorithm yields a 1/2approximation [14] for this problem. For certain special cases, e.g. max|S|≤k f(S), the greedy algorithm yields a (1− 1/e)-approximation. It is known that this is optimal both in the value oracle model (where the only access to...

The P/FDM object database is based on a semantic data model in which stored data is integrated with derived data which is computed by Prolog rules retrieved from the class de-scriptors stored in the database. These rules may also be inherited. They are generated from declarative deenitions expressed in the functional data language Daplex. Other Prolog rules are generated from integrity constrai...

This paper studies optimal power allocation to minimize symbol error rate (SER) of amplify-and-forward cooperative diversity networks. First, we analytically solve optimal power allocation problem to minimize SER for three different scenarios, namely, multi-branch single-relay, single-branch multi-relay and multi-branch multi-relay cooperative diversity networks, all subject to a given total re...

an indirect tarns-log production function was employed to estimate the demand functions for such inputs as: fertilizer, seed, pesticide, water recourse and machinery as subject to budget constraint and while using data related to cotton producers in the three provinces of north khorasan, khorasane razavi, and south khorasan in 2007-8. lagrange coefficients with relation to cotton producers in t...

this paper provides an analysis of persian verbs within the framework of optimality theory. to be more specific, it mainly cocentrates on past and present stems of persian verbs. since analyzing this subject within the derivational framework would result phonological rules which are not natural, it is analysed by optimality theory which is one of the constraint-based approach. based on this, we...