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Nowadays, searches for webpages of a person with a given name constitute a notable fraction of queries to web search engines. Such a query would normally return webpages related to several namesakes, who happened to have the queri...
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Nowadays, searches for webpages of a person with a given name constitute a notable fraction of queries to web search engines. Such a query would normally return webpages related to several namesakes, who happened to have the queried name, leaving the burden of disambiguating and collecting pages relevant to a particular person (from among the namesakes) on the user. In this article we develop a Web People Search approach that clusters webpages based on their association to different people. Our method exploits a variety of semantic information extracted from Web pages, such as named entities and hyperlinks, to disambiguate among namesakes referred to on the Web pages. We demonstrate the effectiveness of our approach by testing the efficacy of the disambiguation algorithms and its impact on person search.
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Large-area displays made up of several projectors show significant variation in color. Here, we identify different projector parameters that cause the color variation and study their effects on the luminance and chrominance charac...
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Large-area displays made up of several projectors show significant variation in color. Here, we identify different projector parameters that cause the color variation and study their effects on the luminance and chrominance characteristics of the display. This work leads to the realization that luminance varies significantly within and across projectors, while chrominance variation is relatively small, especially across projectors of same model. To address this situation, we present a method to achieve luminance matching across all pixels of a multiprojector display that results in photometrically uniform displays. We use a camera as a measurement device for this purpose. Our method comprises a one-time calibration step that generates a per channel per projector luminance attenuation map (LAM), which is then used to correct any image projected on the display at interactive rates on commodity graphics hardware. To the best of our knowledge, this is the first effort to match luminance across all the pixels of a multiprojector display.
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The authors survey a number of important research topics in ATM (asynchronous transfer mode) networks. The topics covered include mathematical modeling of various types of traffic sources, congestion-control and error-control sche...
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The authors survey a number of important research topics in ATM (asynchronous transfer mode) networks. The topics covered include mathematical modeling of various types of traffic sources, congestion-control and error-control schemes for ATM networks, and priority schemes to support multiple classes of traffic. Standard activity for ATM networks and future research problems in ATM are also presented. It is shown that the cell-arrival process for data sources can be modeled by a simple Poisson process. However, voice sources or video sources require more complex processes because of the correlation among cell arrivals. Due to the effects of high-speed channels, preventive control is more effective in ATM networks than reactive control. Due to the use of optical fibers in ATM networks, the channel error rate is very small. The effects of propagation delay and processing time become significant in such high-speed networks. These fundamental changes trigger the necessity to reexamine the error-control schemes used in existing networks. Due to the diversity of service and performance requirements, the notion of multiple traffic classes is required, and separate control mechanisms should be used according to the traffic classes. The priority scheme is shown to be an effective method to support multiple classes of traffic.
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The main contribution of this paper is the insight that the transmitters' knowledge of channel coherence intervals alone (without any knowledge of the values of channel coefficients) can be surprisingly useful in a multiuser setti...
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The main contribution of this paper is the insight that the transmitters' knowledge of channel coherence intervals alone (without any knowledge of the values of channel coefficients) can be surprisingly useful in a multiuser setting, illustrated by the idea of blind interference alignment that is introduced in this work. Specifically, we explore five network communication problems where the possibility of interference alignment, and consequently the total number of degrees of freedom (DoF) with channel uncertainty at the transmitters, are unknown. These problems share the common property that in each case the best known outer bounds are essentially robust to channel uncertainty and represent the outcome with interference alignment, but the best inner bounds-in some cases conjectured to be optimal-predict a total collapse of DoF, thus indicating the infeasibility of interference alignment under channel uncertainty at transmitters. For each of these settings we show that even with no knowledge of channel coefficient values at the transmitters, under certain heterogeneous block fading models, i.e., when certain users experience smaller coherence time/bandwidth than others, blind interference alignment can be achieved. In each case we also establish the DoF optimality of the blind interference alignment scheme.
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A planar single-layer single-feed Fabry-Pérot cavity antenna is designed and fabricated to operate at 60 GHz. The simplicity and planarity of this design is achieved by using only a laminated and commercially available dielectri...
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A planar single-layer single-feed Fabry-Pérot cavity antenna is designed and fabricated to operate at 60 GHz. The simplicity and planarity of this design is achieved by using only a laminated and commercially available dielectric slab, forming the cavity of the antenna, and by exciting the antenna through a planar feed, that is, a coplanar-waveguide-fed slot-dipole, printed directly on the ground plane of the cavity. The backward radiation because of a feeding-slot on the ground plane of the cavity is also investigated and a new closed form formula is presented. The radiation performance of the fabricated antenna is measured using an automated measurement setup built to characterise high-gain millimetre-wave antennas being probed on the opposite side of the main radiation beam.
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Traditionally, dynamic linkers merely combined previously compiled pieces of code. Faster processors are now making outright code generation at load time practical, leading to cross-platform portability at very little extra cost. ...
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Traditionally, dynamic linkers merely combined previously compiled pieces of code. Faster processors are now making outright code generation at load time practical, leading to cross-platform portability at very little extra cost. While the central idea behind dynamic linking is quite straightforward, it can be implemented through a surprising variety of strategies. The author contrasts three simple dynamic linking schemes with two much more elaborate strategies. The latter represent a workload shift from the compiler to the dynamic linker, just as dynamic linking itself represents a shift that moves the functions of a separate linker into the loader. Because the new techniques promise the profound additional benefit of cross-platform portability, they will most likely displace the currently popular linking-loader approach.
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CSCW and groupware emerged in the 1980s from shared interests among product developers and researchers in diverse fields. Today, it must overcome the difficulties of multidisciplinary interaction. This article describes the people...
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CSCW and groupware emerged in the 1980s from shared interests among product developers and researchers in diverse fields. Today, it must overcome the difficulties of multidisciplinary interaction. This article describes the people and the work found under the CSCW umbrella. Issues considered include: research and design areas, software development, office automation, small-group versus systems approach, US and European differences; and the history of groupware.
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Suppose you're a member of a few development teams, working with people who are geographically dispersed. You're using distributed groupware to work with your team mates. How do you decide when to work on a project and when to ign...
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Suppose you're a member of a few development teams, working with people who are geographically dispersed. You're using distributed groupware to work with your team mates. How do you decide when to work on a project and when to ignore requests to work on a project, when there are enough users on the groupware system to bother using it, who is available to answer a question, and which applications should get the most real estate on your screen? To help answer these questions, distributed groupware systems must indicate something about the social world they represent-who is on the system and what they are doing. User interfaces for groupware (or computer supported cooperative work (CSCW) applications) must therefore convey social information. It's energizing to know, for example, that your team mates are busy working away on a project. And it's nice to know when your friends or colleagues are available on a chat system. You might not need to know the semantics of the messages or documents involved, just that some activity is occurring. This is true for systems used by work groups as well as those used by an organization or a community of users. We think such social indicators should be a standard part of the CSCW user interface. On the basis of social psychology theory, we believe that a class of social indicator, which we call social activity indicators, is a simple, powerful way to improve user-interface functionality. Furthermore, social activity indicators are easy to build.
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Recent advances in neurophysiology have led to the development of complex dynamical models that describe the connections and causal interactions between different regions of the brain. These models are able to accurately mimic the...
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Recent advances in neurophysiology have led to the development of complex dynamical models that describe the connections and causal interactions between different regions of the brain. These models are able to accurately mimic the event-related potentials observed by EEG/MEG measurement systems, and are considered to be key components for understanding brain functionality. In this paper, we focus on a class of nonlinear dynamic causal models (DCM) that are described by a set of connectivity parameters. In practice, the DCM parameters are inferred using data obtained by an EEG or MEG sensor array in response to a certain event or stimulus, and then used to analyze the strength and direction of the causal interactions between different brain regions. The usefulness of these parameters in this process will depend on how accurately they can be estimated, which in turn will depend on noise, the sampling rate, number of data samples collected, the accuracy of the source localization and reconstruction steps, etc. The goals of this paper are to present several algorithms for DCM parameter estimation, derive Cramér-Rao performance bounds for the estimates, and compare the accuracy of the algorithms against the theoretical performance limits under a variety of circumstances. The influence of noise and sampling rate will be explicitly investigated.
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We present a statistical optimization framework for solving the end-to-end problem of multiple antenna transmission of progressive images over noisy channels. Such channels exhibit temporally correlated loss characteristics and ar...
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We present a statistical optimization framework for solving the end-to-end problem of multiple antenna transmission of progressive images over noisy channels. Such channels exhibit temporally correlated loss characteristics and are associated with wireless communication links. In our study, we protect the progressive bitstream associated with an image source utilizing a family of rate compatible punctured Reed-Solomon (RS) product codes along with receiver feedback. We consider the impacts of transmission bit errors as well as packet erasures. To cope with the impact of random bit errors, we formulate an optimization problem aimed at minimizing the end-to-end expected distortion of a reconstructed image subject to rate and efficiency constraints. In order to eliminate the impact of packet erasures, we propose utilizing an algorithm that is capable of statistically guaranteeing the delivery of a number of packet sets associated with a progressive bitstream. Our experiments capture the effects of embedding multiple antennas in the transmission of progressive images over wireless tandem channels. Under identical power constraints, our results show that increasing the number of antennas on either transmitting or receiving sides improves the quality of a reconstructed image. Further, the use of receive diversity used in conjunction with simple communication coding schemes such as maximum ration combining (MRC) yields more improvements than the use of transmit diversity used in conjunction with comparable communication coding schemes such as space-time block code (STBC). Finally, the use of receiver feedback can further improve the quality of an image reconstructed in the absence of feedback.
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