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.

Computer aided fixture design: Recent research and trends

Abstract: Widely used in manufacturing, fixtures have a direct impact upon product manufacturing quality, productivity and cost, so much attention has already been paid to the research of computer aided fixture design (CAFD) and many achievements in this field have been reported. In this paper, a literature survey of computer aided fixture design and automation over the past decade is proposed. First, an introduction is given on the fixture applications in industry. Then, significant works done in the CAFD field, including their approaches, requirements and working principles are discussed. Finally, some prospective research trends are also discussed.

Evaluation of Rejuvenator's Effectiveness with Conventional Mix Testing for 100% Reclaimed Asphalt Pavement Mixtures:

Abstract: This paper presents research evaluating the effectiveness of rejuvenators for production of very high (40% to 100%) reclaimed asphalt pavement (RAP) content mixtures. Nine differently originated softening agents were tested; these included plant oils, waste-derived oils, engineered products, and traditional and nontraditional refinery base oils. Two different dosages of the agents were added to binder extracted from RAP to evaluate their softening potential through testing of kinematic viscosity and penetration at two different temperatures. At 25°C the softening efficiency varied by a factor of 12 between the most and least effective rejuvenators. Consistency results at different temperatures were used to express temperature susceptibility by means of penetration index (PI), penetration-viscosity number, and bitumen test data chart of the softened binders. The PI results varied measurably depending on the rejuvenator and supported the low-temperature mixture test results, showing that PI may be a good an...

LEDS: Providing Location-Aware End-to-End Data Security in Wireless Sensor Networks

Abstract: Providing desirable data security, that is, confidentiality, authenticity, and availability, in wireless sensor networks (WSNs) is challenging, as a WSN usually consists of a large number of resource constraint sensor nodes that are generally deployed in unattended/hostile environments and, hence, are exposed to many types of severe insider attacks due to node compromise. Existing security designs mostly provide a hop-by-hop security paradigm and thus are vulnerable to such attacks. Furthermore, existing security designs are also vulnerable to many types of denial of service (DoS) attacks, such as report disruption attacks and selective forwarding attacks and thus put data availability at stake. In this paper, we seek to overcome these vulnerabilities for large-scale static WSNs. We come up with a location-aware end-to-end security framework in which secret keys are bound to geographic locations and each node stores a few keys based on its own location. This location-aware property effectively limits the impact of compromised nodes only to their vicinity without affecting end-to-end data security. The proposed multifunctional key management framework assures both node-to-sink and node-to-node authentication along the report forwarding routes. Moreover, the proposed data delivery approach guarantees efficient en-route bogus data filtering and is highly robust against DoS attacks. The evaluation demonstrates that the proposed design is highly resilient against an increasing number of compromised nodes and effective in energy savings.

Bandgap narrowing in moderately to heavily doped silicon

Abstract: A model of bandgap reduction in silicon through the stored electrostatic energy of majority-minority carrier pairs is developed and compared with experimental results in the doping range from 3 × 1017to 1.5 × 1020/cm3at room temperature. An analytic expression for the bandgap reduction in nondegenerate material is obtained \delta\epsilon _{g} = 3q^{2}/(16\pi \epsilon) \cdot (q^{2}n/\epsilon kT)1/2having a square-root dependence on the majority carrier concentration. At room temperature this becomes \delta\epsilon _{g} = 22.5 (n/10^{18})^{1/2} meV. In degenerate material, the bandgap reduction is independent of temperature, following the relationship \delta \epsilon _{g} = 162 (n/10^{20})^{1/6} meV. The experimental data at room temperature are in excellent agreement with this theory. Plots of bandgap narrowing as a function of doping level are presented for a number of temperatures.