Worcester Polytechnic Institute

About: Worcester Polytechnic Institute is a education organization based out in Worcester, Massachusetts, United States. It is known for research contribution in the topics: Computer science & Population. The organization has 6270 authors who have published 12704 publications receiving 332081 citations. The organization is also known as: WPI.

Knowledge and Control for a Mechanical Design Expert System

Abstract: M ost first-generation expert systems have been rule-based with a separate inference engine. However, a large unstructured collection of rules clearly lacks validity as a realistic model of design because reducing all knowledge to a single form does not recognize that there are many different types of knowledge used in any design problem-solving activity. Using such a collection of rules also does not recognize that design knowledge forms into clusters. Nor does it specify where or when this knowledge is to be applied, since different clusters ofknowledge may be applicable at different times. Similarly, using a single, central allpurpose inference engine ignores the richness of design problem-solving. Yet another problem is the potential for unfocused system behavior because all rules have equal status in the system and have equal potential for use. Many systems structure rules into sets. However, these sets are based on subtasks rather than on types of knowledge, 1-3 and the problem solving is still uniform, as the same inference engine acts on each rule set. Advocates of such structuring claim the subtasks can be solved linearly with no backtracking between tasks and with only minimal backtracking within tasks. Such subtask structure tells us more about the nature ofthe domain than about design, since it is clear that design decisions of any kind can often be wrong and, if so, will lead to attempts to recover from failure. The uniform rule representation and the lack of knowledge-dependent structure does not provide clear predictions about an expert's failure-recovery behavior. These problems stem mainly from a basic mismatch between the level of the tools available to build systems and the level of abstraction of the design task.

A Scalable GF(p) Elliptic Curve Processor Architecture for Programmable Hardware

Abstract: This work proposes a new elliptic curve processor architecture for the computation of point multiplication for curves defined over fields GF(p). This is a scalable architecture in terms of area and speed specially suited for memory-rich hardware platforms such a field programmable gate arrays (FPGAs). This processor uses a new type of high-radix Montgomery multiplier that relies on the precomputation of frequently used values and on the use of multiple processing engines.

Packed Tubular Reactor Modeling and Catalyst Design using Computational Fluid Dynamics

Abstract: Computational fluid dynamics (CFD) is rapidly becoming a standard tool for the analysis of chemically reacting flows. For single-phase reactors, such as stirred tanks and “empty” tubes, it is already well-established. For multiphase reactors such as fixed beds, bubble columns, trickle beds and fluidized beds, its use is relatively new, and methods are still under development. The aim of this chapter is to present the application of CFD to the simulation of three-dimensional interstitial flow in packed tubes, with and without catalytic reaction. Although the use of CFD to simulate such geometrically complex flows is too expensive and impractical currently for routine design and control of fixed-bed reactors, the real contribution of CFD in this area is to provide a more fundamental understanding of the transport and reaction phenomena in such reactors. CFD can supply the detailed three-dimensional velocity, species and temperature fields that are needed to improve engineering approaches. In particular, this chapter considers the development of CFD methods for packed tube simulation by finite element or finite volume solution of the governing partial differential equations. It discusses specific implementation problems of special relevance to packed tubes, presents the validation by experiment of CFD results, and reviews recent advances in the field in transport and reaction. Extended discussion is given of two topics: heat transfer in packed tubes and the design of catalyst particles for steam reforming.

Role of cranberry juice on molecular-scale surface characteristics and adhesion behavior of Escherichia coli.

Abstract: Cranberry juice has long been believed to benefit the prevention and treatment of urinary tract infections (UTIs). As the first step in the development of infection, bacterial adhesion is of great research interest, yet few studies have addressed molecular level adhesion in this context. P-fimbriated Escherichia coli play a major role in the development of a serious type of UTI, acute pyelonephritis. Experiments were conducted to investigate the molecular-scale effects of cranberry juice on two E. coli strains: HB101, which has no fimbriae, and the mutant HB101pDC1 which expresses P-fimbriae. Atomic force microscopy (AFM) was used to investigate both bacterial surface characteristics and adhesion forces between a probe surface (silicon nitride) and the bacteria, providing a direct evaluation of bacterial adhesion and interaction forces. Cranberry juice affected bacterial surface polymer and adhesion behavior after a short exposure period (<3 h). Cranberry juice affected the P-fimbriated bacteria by decreasing the adhesion forces between the bacterium and tip and by altering the conformation of the surface macromolecules on E. coli HB101pDC1. The equilibrium length of polymer (P-fimbriae) on this bacterium decreased from approximately 148 to approximately 48 nm upon being exposed to cranberry juice. Highly acidic conditions were not necessary for the prevention of bacterial adhesion, since neutralization of cranberry juice solutions to pH = 7.0 allowed us to observe differences in adhesion between the E. coli strains. Our results demonstrate molecular-level changes in the surfaces of P-fimbriated E. coli upon exposure to neutralized cranberry juice.