Search

The author discusses the special issue of the periodical "IEEE Transactions on Microwave Theory and Techniques" which focuses on papers presented in the 2009 Radio Frequency Integrated Circuits (RFIC) Symposium held in Boston, Massachusetts in June. She reports that the acceptance rate for the papers submitted was high due to the good quality of the revised manuscripts. She explains how the reviewers for the special issue were selected.

We propose the correlated orienteering problem (COP) as a novel nonlinear extension to the classic orienteering problem (OP). With the introduction of COP,  it becomes possible to model the planning of informative tours for the persistent monitoring of a spatiotemporal field with time-invariant spatial correlations using autonomous mobile robots, in which the robots are range- or time-constrained. Our focus in this paper is QCOP, a quadratic COP  instantiation that looks at correlations between neighboring nodes in a node network. The main feature of QCOP  is a quadratic utility function capturing the said spatial correlation. We solve QCOP using mixed integer quadratic programming, with the resulting anytime algorithm capable of planning multiple disjoint tours that maximize the quadratic utility. In particular, our algorithm can quickly plan a near-optimal tour over a network with up to $150$ nodes. Beside performing extensive simulation studies to verify the algorithm's correctness and characterize its performance, we also successfully applied QCOP  to two realistic persistent monitoring tasks: 1) estimation over a synthetic spatiotemporal field and 2) estimating the temperature distribution in the state of Massachusetts in the United States. [ABSTRACT FROM AUTHOR]

The article presents an introduction to the special section related to International Conference on Software Engineering (ICSE'97), published in the August 1998 issue of the journal "IEEE Transactions on Software Engineering." Authors say that ICSE was held in Boston Massachusetts, in the week of May 17-23, 1997. The main goal of the conference was to meet needs and expectations of a large variety of attendees. The program committee of the conference was involved in a comprehensive reviewing process of papers submitted. At the end of this process, three papers were selected for publication. In the first paper, "Evaluating Testing Methods by Delivered Reliability," researchers discuss a method for evaluating the effectiveness of testing, based on a measure of the program reliability after testing. The second paper "Analyzing Partially Implemented Real-Time System," presents a technique for analyzing partially-implemented real-time systems. The third paper "Communication Metrics for Software Development," discusses results of comprehensive experiment whose goal was to evaluate the effectiveness of a set of communication metrics.

SDD-1, A System for Distributed Databases, is a distributed database system being developed by Computer Corporation of America (CCA), Cambridge, MA. SDD-1 permits data to be stored redundantly at several database sites in order to enhance the reliability and responsiveness of the system and to facilitate upward scaling of system capacity. This paper describes the method used by SDD-1 for updating data that are stored redundantly. Redundant updating can be costly because it may potentially involve extensive intercomputer communication overhead in order to lock all copies of data being updated. The method described here avoids this overhead by identifying cases in which it is not necessary to perform this global database locking. The identification of transactions that do not require global locking is based on a predefinition of transaction classes performed by the database administrator using an analysis technique described herein. The classes defined are used at run time to decide what level of synchronization is needed for a given transaction. It is important to note that this predefinition activity in no way limits the transactions that the system can accept; it merely permits more efficient execution of those types of transactions that were anticipated. [ABSTRACT FROM AUTHOR]

A microelectromechanical system (MEMS) turbocharger has been designed, fabricated, and tested as part of a Massachusetts Institute of Technology program aimed at producing a microfabricated gas turbine engine for portable power applications. A gas turbine engine requires high-speed high-efficiency turbomachinery operating at tip speeds of several hundred meters per second. This MEMS turbocharger serves to demonstrate these requirements. The turbocharger's silicon rotor, which is supported on hydrostatic gas thrust and journal bearings in a silicon stator housing, was spun to 480 000 rpm, corresponding to a tip speed of 200 m/s. This paper discusses critical fabrication processes that enabled the capabilities of this device. Operational issues and test results are also presented. The turbocharger's compressor demonstrated a pressure ratio of 1.21 at a mass flow rate of 0.13 g/s, with a combined compressor-turbine spool efficiency of 0.24. Under these conditions, the turbine produced about S W of power. Results from the simultaneous operation of a spinning rotor and burning combustor within the microscale turbocharger are also presented. Experimental results compare well with analytical models and computations. [ABSTRACT FROM AUTHOR]

In this brief, we present new preprocessing techniques for electrocardiogram signals, namely, dc equalization and complexity sorting, which when applied can improve current 2-D compression algorithms. The experimental results with signals from the Massachusetts Institute of Technology - Beth Israel Hospital (MIT-BIH) database outperform the ones from many state-of-the-art schemes described in the literature. [ABSTRACT FROM AUTHOR]

The article focuses on the "International Symposium on Technology and Society," themed at Globalizing Technological Education, convened at the Worcester Polytechnic Institute (WPI) in Worcester, Massachusetts. The meeting was made possible by the dedicated work of WPI professors. Persons from a variety of nations and from disciplines that included engineering, science, policy, law and philosophy took part in this meeting. In this meeting current and future dimensions of technology practice within a global context emerged as a subject of critical examination.

Wireless channel data was collected in Cambridge, Massachusetts for diverse propagation environments over distances ranging from tens of meters to several kilometers using mobile 2.4-GHz transmitters and receivers. The 20-Mhz bandwidth signals from eight individually movable van-top antennas were Nyquist sampled simultaneously with 12-bit accuracy. Although path-loss variance for any given link length within single residential/urban neighborhoods was large, single streets typically exhibited path-loss, L(dB) = -10 log10(Pr/Pt) ≅ 10α log10 r + C, where P is the received or transmitted power, r the link-length, α the street-dependent path-loss coefficient, and C the loss incurred at street intersections. Measurements yielded α ≅ 1.5 + 3.2β±0.27 for 2 < α < 5; β is the fraction of the street length having a building gap on either side. Experiments over links as short as 100 meters indicate a 10-dB advantage in estimating path loss for this model compared to optimal linear estimators based on link length alone. Measured air-to-ground links were well modeled by α = 2 for the elevated LOS path, and by stochastic log-normal attenuation for the ground-level scattering environment. These models permit path-loss predictions based on readily accessible environmental parameters, and lead to efficient nodal placement strategies for full urban coverage. [ABSTRACT FROM AUTHOR]

Describes the design of one-kilo-ampere high temperature superconducting (HTS) leads developed by American Magnetics Inc. (AMI) and the Massachusetts Institute of Technology (MIT). Operation in the current-sharing mode; Reliance on vapor cooling; Applicability of AMI-MIT leads to liquid helium cooled superconducting magnets.

In this article, we present a feasibility analysis for performing vehicular dynamic spectrum access across vacant television channels via a queueing theory approach. In this study, we model the vacant TV channels as a multiserver, multipriority, preemptive queue. Queueing theory has been extensively employed in the open literature to model multiple access architectures as well as analyze network performance in both wired and wireless communication frameworks. On the other hand, to the best of the authors? knowledge, not many researchers have tried to resort to a queueing theory approach to analyze dynamic spectrum access networks on a system level, including the specific case of vehicular dynamic spectrum access (VDSA). Leveraging previously reported quantitative measurements obtained from a wireless spectrum measurement campaign conducted along a major interstate highway (I-90) located in Massachusetts, we modeled vacant TV channels as a multiserver queueing system in which available servers represent vacant TV channels. The servers become unavailable from the perspective of a vehicle in a time/location-varying fashion such that they represent spatially occupied TV channels. Both M/M/m and M/G/m models are employed to evaluate the probability that a vehicle finds all channels busy, as well as to derive the expected waiting times. We also consider cases where there are multiple priority classes of service requests such as a channel request by a firstresponder vehicle. [ABSTRACT FROM PUBLISHER]

There are and have been many power couples: Brad and Angelina, Bill and Hillary, Siegfried and Roy, Bogie and Bacall. ComSoc boasts its own power couple: Milica Stojanovic and Zoran Zvonar. To our knowledge, they are the first married couple to be elevated to IEEE Fellow in the same year. [ABSTRACT FROM PUBLISHER]