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: Population & Data envelopment analysis. The organization has 6270 authors who have published 12704 publications receiving 332081 citations. The organization is also known as: WPI.

Propagation dynamics of optical vortices

Abstract: Optical vortices in linear and nonlinear media may exhibit propagation dynamics similar to hydrodynamic vortex phenomena. Analytical and numerical methods are used to describe and investigate the interaction between vortices and the background field. We demonstrate that optical vortices that have quasi-point core functions, such as optical vortex solitons, may orbit one another at rates that are orders of magnitude larger than those with nonlocalized cores.

Privacy-preserving multi-keyword text search in the cloud supporting similarity-based ranking

Abstract: With the increasing popularity of cloud computing, huge amount of documents are outsourced to the cloud for reduced management cost and ease of access. Although encryption helps protecting user data confidentiality, it leaves the well-functioning yet practically-efficient secure search functions over encrypted data a challenging problem. In this paper, we present a privacy-preserving multi-keyword text search (MTS) scheme with similarity-based ranking to address this problem. To support multi-keyword search and search result ranking, we propose to build the search index based on term frequency and the vector space model with cosine similarity measure to achieve higher search result accuracy. To improve the search efficiency, we propose a tree-based index structure and various adaption methods for multi-dimensional (MD) algorithm so that the practical search efficiency is much better than that of linear search. To further enhance the search privacy, we propose two secure index schemes to meet the stringent privacy requirements under strong threat models, i.e., known ciphertext model and known background model. Finally, we demonstrate the effectiveness and efficiency of the proposed schemes through extensive experimental evaluation.

Generation Y, web design, and eye tracking

Abstract: Generation Y (age 18-31) is a very large and economically powerful generation, containing eighty-two million people and spending $200 billion annually It is not surprising that companies are interested in gaining the patronage of this group, particularly via the web Surprisingly, very little research into making web pages appealing to this important demographic has been done This paper addresses this need through two separate studies The first, an online survey, provides evidence that our proposed score for predicting the visual appeal of web pages reflects the self report measure of what pages Generation Y likes To refine these findings, an eye tracking study is conducted using the pages that were most and least liked in Study I Participants' eye movement is tracked while browsing these pages, providing evidence of what attracts their attention The results of these two studies suggest that Generation Y may prefer pages that include a main large image, images of celebrities, little text, and a search feature This research has important implications

Production of renewable jet fuel range alkanes and commodity chemicals from integrated catalytic processing of biomass

Abstract: This article presents results from experimental studies and techno-economic analysis of a catalytic process for the conversion of whole biomass into drop-in aviation fuels with maximal carbon yields. The combined research areas highlighted include biomass pretreatment, carbohydrate hydrolysis and dehydration, and catalytic upgrading of platform chemicals. The technology centers on first producing furfural and levulinic acid from five- and six-carbon sugars present in hardwoods and subsequently upgrading these two platforms into a mixture of branched, linear, and cyclic alkanes of molecular weight ranges appropriate for use in the aviation sector. Maximum selectivities observed in laboratory studies suggest that, with efficient interstage separations and product recovery, hemicellulose sugars can be incorporated into aviation fuels at roughly 80% carbon yield, while carbon yields to aviation fuels from cellulose-based sugars are on the order of 50%. The use of lignocellulose-derived feedstocks rather than commercially sourced model compounds in process integration provided important insights into the effects of impurity carryover and additionally highlights the need for stable catalytic materials for aqueous phase processing, efficient interstage separations, and intensified processing strategies. In its current state, the proposed technology is expected to deliver jet fuel-range liquid hydrocarbons for a minimum selling price of $4.75 per gallon assuming nth commercial plant that produces 38 million gallons liquid fuels per year with a net present value of the 20 year biorefinery set to zero. Future improvements in this technology, including replacing precious metal catalysts by base metal catalysts and improving the recyclability of water streams, can reduce this cost to $2.88 per gallon.