18103228
In-Network Processing of Nearest Neighbor Queries for Wireless Sensor Networks
Wireless sensor networks have been widely used for civilian and military applications, such as environmental monitoring and vehicle tracking. The sensor nodes in the network have the abilities to sense, store, compute and communicate. To enable object tracking applications, spatial queries such as nearest neighbor queries are to be supported in these networks. The queries can be injected by the user at any sensor node. Due to the limited power supply for sensor nodes, energy efficiency is the major concern in query processing. Centralized data storage and query processing schemes do not favor energy efficiency. In this paper, we propose a distributed scheme called DNN for in-network processing of nearest neighbor queries. A cost model is built to analyze the performance of DNN. Experimental results show that DNN outperforms the centralized scheme significantly in terms of energy consumption and network lifetime.
17927523
An energy-efficient and access latency optimized indexing scheme for wireless data broadcast
Data broadcast is an attractive data dissemination method in mobile environments. To improve energy efficiency, existing air indexing schemes for data broadcast have focused on reducing tuning time only, i.e., the duration that a mobile client stays active in data accesses. On the other hand, existing broadcast scheduling schemes have aimed at reducing access latency through nonflat data broadcast to improve responsiveness only. Not much work has addressed the energy efficiency and responsiveness issues concurrently. This paper proposes an energy-efficient indexing scheme called MHash that optimizes tuning time and access latency in an integrated fashion. MHash reduces tuning time by means of hash-based indexing and enables nonflat data broadcast to reduce access latency. The design of hash function and the optimization of bandwidth allocation are investigated in depth to refine MHash. Experimental results show that, under skewed access distribution, MHash outperforms state-of-the-art air indexing schemes and achieves access latency close to optimal broadcast scheduling
2273900
Channel estimation and interference suppression for space-time coded systems in frequency-selective fading channels
Summary It is of great interest to provide high data rate services in wireless communication systems. In order to support such services, it is desirable to extend space-time (ST) coding, originally proposed for known, frequency-nonselective fading channels, to unknown, multipath channels. In this paper, we consider the problem of interference suppression for wireless TDMA (time division multiple access) systems equipped with multiple transmit antennas and receive antennas in frequency-selective fading channels. A novel scheme with space-time block coding based transmit diversity (STTD) is presented to estimate the multipath channel, coherently demodulate information symbols, and meanwhile suppress radio interference. The proposed scheme is simple to implement and able to mitigate interference of various origins, including intersymbol interference (ISI), cochannel interference (CCI), and others. Numerical examples are presented to illustrate the performance of the proposed estimator and detector in multipath Rayleigh-fading channels. Copyright  2002 John Wiley & Sons, Ltd.
32948109
Electronic image stabilization using multiple visual cues
Image stabilization is a key preprocessing step in dynamic image analysis and deals with the removal of unwanted image motion in a video sequence. This paper presents an integrated algorithm for the problem of image stabilization. The algorithm combines various visual cues such as points and horizon lines, and relies on an extended Kalman filter for the estimation of parameters of interest. We study both calibrated and uncalibrated stabilization cases, and consider the problem of the selection of model dynamics for the estimation of warping parameters. Experimental results from video sequences generated from off-road vehicle platforms show good performance of stabilization algorithm.
9590852
Web-based information retrieval support systems: building research tools for scientists in the new information age
The concept of Web-based information retrieval support systems (WIRSS) is introduced. The needs for WIRSS are shown by a detailed case study of existing research article indexing and citation analysis systems, such as current content, DBLP, science citation index and CiteSeer. The objective of WIRSS is to build new and effective research tools for scientists to access, explore and use information on the Web, which may lead to improved research productivity and quality.
206625201
Web Intelligence (WI)
This paper is about a new research field called Web Intelligence (WI for short). We try to explain the needs for coining the term as a sub-discipline of computer science for systematic studies on advanced Web related theories and technologies, as well as the design and implementation of Intelligent Web Information Systems (IWIS). Background information and related topics are discussed in an attempt to demonstrate why we consider WI to be a subject worthy of study and, at the same time, to establish a starting point for the further development of WI.
449421
Web-based Research Support Systems
Web-based research support systems (WRSS) are a specific type of Web-based support systems (WSS) that support research activities for scientists. They are motivated by the challenges and opportunities of the Web, as well as the needs of scientists. The recent advancements of computer and Web technologies make the implementation of WSS feasible. A general framework of WSS is presented by considering its basic issues. Within the framework, the principles and issues of WRSS are examined. From the conceptual point of view, WRSS may be considered as a new subfield of study. It focuses on a more systematic and coherent treatment of existing isolated studies of research support. From the implementation point of view, WRSS are based on assembling, integration, and adaptation of existing computer technology and information systems for the purpose of research support. The results of WRSS may lead to new and viable research tools.