Optimal Server Acquisition in Open Queueing Networks

Several production and flexible manufacturing systems can naturally be modelled using queueing networks. In this paper, we consider the problem of acquiring servers for the nodes of an open queueing network, so as to optimize the steady-state mean virtual system parameters subject to a budget constraint. A partial enumeration scheme and a heuristic method have been proposed to solve this problem. Empirical results based on randomly generated test problems are used to identify a class of problems for which the heuristic performs well.     

Efficient light harvesting and energy transfer in organic-inorganic hybrid multichromophoric materials

Thin films of silica hybrid materials consisting of two to three covalently bound organic chromophores at different ratios were conveniently synthesized and fabricated. The photophysical properties of these materials have been studied. The fluorescence spectra reveal complete fluorescence resonance energy transfer (FRET) from donor to acceptor, and the light-harvesting ability of these hybrid materials increases with increasing the molar fraction of donor chromophore. In a three-chromophore system, the energy is transferred from 300 to 530 nm successfully. Time-resolved fluorescence experiments are employed to elucidate the average rates and efficiencies (84-97%) of energy transfer in these organic/inorganic hybrid systems. The hybrid materials have been shown to provide antenna effect to facilitate energy transfer and light harvesting.     

Synthesis and photophysical studies of siloxane-tethered cyclophanes

Novel siloxane tethered para divinylarene cyclophanes, containing phenyl, biphenyl and naphthalene rings as the aromatic nuclei, were prepared by the hydrolytic condensation of the corresponding bis{[dimethyl(i-propoxy)silyl]vinyl}arenes under basic conditions.The photophysics of the cyclophanes were investigated using UV and fluorescence spectroscopy.     

On the efficacy of distributed simplex algorithms for linear programming

We consider the use of distributed computation to solve general unstructured linear programs by the inherently serial approach of the simplex method. Timing models for the distributed algorithms are presented to predict results which are then verified empirically. Our results contribute to the identification of all viable exploitations of distributed computing which is likely to become a prevalent environment.Dedicated to Professor George B. Dantzig on the occasion of his eightieth birthday.     

On the rigidity of polynorbornenes with dipolar pendant groups

A range of polynorbornenes (PNBs) with fused dipolar pendant groups at C-5,6 positions was synthesized by ring-opening metathesis polymerization catalyzed by a ruthenium carbene complex (Grubbs I). Photophysical studies, EFISH measurements, and atomic force microscopy images have been used to investigate the structures and morphology of these polymers. These results suggest that the polymers may adopt rigid rod-like structures. The presence of the double bonds in PNBs appeared to be indispensable for the rigidity of the polymers. Interaction between unsaturated pendant groups may result in coherent alignment leading to a rod-like structure.     

Norbornadiene as an efficient hydrogen scavenger for the palladium-catalyzed conversion of hydrosilanes to alkoxysilanes

A palladium-catalyzed mild and efficient method for the alcoholysis of hydrosilanes containing a C=C bond in the presence of norbornadiene (NBD) is reported. The highly strained NBD acts as a hydrogen scavenger, which abstracts the hydrogen produced during the process, protecting the C=C bond from being hydrogenated.     

Designing specific inhibitors against dihydrofolate reductase of W. bancrofti towards drug discovery for lymphatic filariasis

Structural Chemistry - Lymphatic filariasis (LF) is one among the leading neglected diseases caused by mosquitoe-borne parasite Wuchereria bancrofti to humans. Though drugs are available for the...     

Solution processable phosphorescent dendrimers based on cyclic phosphazenes for use in organic light emitting diodes (OLEDs)

A novel solution processable phosphorescent dendrimer based on cyclic phosphazene (CP) cores has been prepared and used as emissive layers in simple OLED architectures, providing efficiencies of 24.0 cd A(-1) and 16.7 lm W(-1).     

Decomposition of linear programs using parallel computation

This paper describes DECOMPAR: an implementation of the Dantzig-Wolfe decomposition algorithm for block-angular linear programs using parallel processing of the subproblems. The software is based on a robust experimental code for LP decomposition and runs on the CRYSTAL multicomputer at the University of Wisconsin-Madison. Initial computational experience is reported. Promising directions in future development of this approach are discussed.Research supported in part by the Office of Naval Research under grant N00014-87-K-0163.     

A model for standardizing human decisions concerning service-contracts management

Increased expectations of today’s customers are causing businesses to offer a variety of warranty contracts for their products. Because of the intense customer contact that takes place during the process of supporting a contract, the planning for contracts has to not only contend with the unpredictable and low demands of the service parts, but must also rely on human decision-making concerning a number of subjective factors. These subjective factors, which are related to the customer, the contract and the contracted product, have seldom been considered in the literature on inventory planning. Moreover, the evaluation of subjective factors often becomes non-standardized and non-coordinated among the geographically dispersed decision-makers of an organization, as was the situation with a Fortune 100 company’s case that motivated this paper. We propose a combination of a heuristic procedure along with the Analytical Hierarchy Process technique that has not been applied in the inventory-planning setting. We also demonstrate how a Web-based information system can be used to standardize the decision process, and discuss the implications of the system on the motivational case. Computational results are also provided to show the effectiveness of the heuristics.