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64
Constructing Internet Coordinate System Based on Delay Measurement
, 2003
"... In this paper, we consider the problem of how to represent the locations of Internet hosts in a Cartesian coordinate system to facilitate estimate of the network distance between two arbitrary Internet hosts. We envision an infrastructure that consists of beacon nodes and provides the service of est ..."
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Cited by 112 (3 self)
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In this paper, we consider the problem of how to represent the locations of Internet hosts in a Cartesian coordinate system to facilitate estimate of the network distance between two arbitrary Internet hosts. We envision an infrastructure that consists of beacon nodes and provides the service of estimating network distance between two hosts without direct delay measurement. We show that the principal component analysis (PCA) technique can e#ectively extract topological information from delay measurements between beacon hosts. Based on PCA, we devise a transformation method that projects the distance data space into a new coordinate system of (much) smaller dimensions. The transformation retains as much topological information as possible and yet enables end hosts to easily determine their locations in the coordinate system. The resulting new coordinate system is termed as the Internet Coordinate System (ICS). As compared to existing work (e.g., IDMaps [1] and GNP [2]), ICS incurs smaller computation overhead in calculating the coordinates of hosts and smaller measurement overhead (required for end hosts to measure their distances to beacon hosts). Finally, we show via experimentation with reallife data sets that ICS is robust and accurate, regardless of the number of beacon nodes (as long as it exceeds certain threshold) and the complexity of network topology.
kPlane Clustering
 Journal of Global Optimization
, 2000
"... A finite new algorithm is proposed for clustering m given points in ndimensional real space into k clusters by generating k planes that constitute a local solution to the nonconvex problem of minimizing the sum of squares of the 2norm distances between each point and a nearest plane. The key to th ..."
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Cited by 42 (3 self)
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A finite new algorithm is proposed for clustering m given points in ndimensional real space into k clusters by generating k planes that constitute a local solution to the nonconvex problem of minimizing the sum of squares of the 2norm distances between each point and a nearest plane. The key to the algorithm lies in a formulation that generates a plane in ndimensional space that minimizes the sum of the squares of the 2norm distances to each of m1 given points in the space. The plane is generated by an eigenvector corresponding to a smallest eigenvalue of an n \Theta n simple matrix derived from the m1 points. The algorithm was tested on the publicly available Wisconsin Breast Prognosis Cancer database to generate well separated patient survival curves. In contrast, the kmean algorithm did not generate such wellseparated survival curves. 1 Introduction There are many approaches to clustering such as statistical [2, 9, 6], machine learning [7, 8] and mathematical programming [15...
The CMU Reconfigurable Modular Manipulator System
 TECHNICAL REPORT
, 1988
"... Modular manipulator designs have long been b een considered for use as research tools, and as the basis for easily
modified industrial manipulators. In these manipulators the links and joints are discrete and modular components
that can be assembled into a desired manipulator configuration. As ha ..."
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Cited by 39 (13 self)
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Modular manipulator designs have long been b een considered for use as research tools, and as the basis for easily
modified industrial manipulators. In these manipulators the links and joints are discrete and modular components
that can be assembled into a desired manipulator configuration. As hardware advances have made actual modular
manipulators practical, various capabilities of such manipulators have gained interest. Particularly desirable is the
ability to rapidly reconfigure such a manipulator, in order to custom tailor i t to specific tasks. T i reconfiguration
hs
greatly enhances the capability of a given amount of manipulator hardware. This paper discusses the development of
a prototype modular manipulator and the implementation of a configuration independent manipulator kinematics
algorithm used for path planning in the prototype.
Multiresolution Histograms and their Use for Recognition
 IEEE transactions on Pattern Analysis and Machine Intelligence
, 2004
"... Abstract—The histogram of image intensities is used extensively for recognition and for retrieval of images and video from visual databases. A single image histogram, however, suffers from the inability to encode spatial image variation. An obvious way to extend this feature is to compute the histog ..."
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Cited by 39 (0 self)
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Abstract—The histogram of image intensities is used extensively for recognition and for retrieval of images and video from visual databases. A single image histogram, however, suffers from the inability to encode spatial image variation. An obvious way to extend this feature is to compute the histograms of multiple resolutions of an image to form a multiresolution histogram. The multiresolution histogram shares many desirable properties with the plain histogram including that they are both fast to compute, space efficient, invariant to rigid motions, and robust to noise. In addition, the multiresolution histogram directly encodes spatial information. We describe a simple yet novel matching algorithm based on the multiresolution histogram that uses the differences between histograms of consecutive image resolutions. We evaluate it against five widely used image features. We show that with our simple feature we achieve or exceed the performance obtained with more complicated features. Further, we show our algorithm to be the most efficient and robust.
Numerical Methods for Simultaneous Diagonalization
 SIAM J. Matrix Anal. Applicat
, 1993
"... We present a Jacobilike algorithm for simultaneous diagonalization of commuting pairs of complex normal matrices by unitary similarity transformations. The algorithm uses a sequence of similarity transformations by elementary complex rotations to drive the offdiagonal entries to zero. We show th ..."
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Cited by 38 (0 self)
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We present a Jacobilike algorithm for simultaneous diagonalization of commuting pairs of complex normal matrices by unitary similarity transformations. The algorithm uses a sequence of similarity transformations by elementary complex rotations to drive the offdiagonal entries to zero. We show that its asymptotic convergence rate is quadratic and that it is numerically stable. It preserves the special structure of real matrices, quaternion matrices and real symmetric matrices.
Note On The Location Of Optimal Classifiers In NDimensional ROC Space
, 1999
"... The comparative study of classifier performance is a worthwhile concern in Machine Learning. Empirical comparisons typically examine unbiased estimates of predictive accuracy of different algorithms  the assumption being that the classifier with the highest accuracy would be the "optimal" choice o ..."
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Cited by 33 (1 self)
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The comparative study of classifier performance is a worthwhile concern in Machine Learning. Empirical comparisons typically examine unbiased estimates of predictive accuracy of different algorithms  the assumption being that the classifier with the highest accuracy would be the "optimal" choice of classifier for the problem. The qualification on optimality is needed here, as choice is restricted to the classifiers being compared, and the estimates are typically subject to sampling errors. Comparisons based on predictive accuracy overlook two important practical concerns, namely (a) class distributions cannot be specified precisely. Distribution of classes in the training set are thus rarely matched exactly on new data; and (b) that the costs of different types of errors may be unequal. Using techniques developed in signal detection, Provost and Fawcett describe an elegant method for the comparative assessment of binary classifiers that takes these considerations into account. Thei...
DiscreteTime Analysis of Adaptive Rate Control Mechanisms
 In Proc. 5th Int. Conference on Data and Communications
, 1994
"... We analyze the performance of a generic feedback flow control mechanism which captures the properties of several such mechanisms recently proposed in the literature. These mechanisms dynamically regulate the rate of data flow into a network based on feedback information about the network state. They ..."
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Cited by 25 (4 self)
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We analyze the performance of a generic feedback flow control mechanism which captures the properties of several such mechanisms recently proposed in the literature. These mechanisms dynamically regulate the rate of data flow into a network based on feedback information about the network state. They are used in a variety of networks and they have been advocated for upcoming highspeed networks. However, they are difficult to model realistically. In this paper, we present a stochastic discretetime approach that yields models which are realistic and yet tractable and computationally easy to solve. For our generic mechanism, the feedback consists of an exponentially averaged estimate of the bottleneck service rate and queue size. We obtain a model described by nonlinear stochastic difference equations. We find the conditions under which these equations converge to a steadystate and we characterize the speed of convergence to steadystate. We then consider a linearized version of the mo...
Multiple Description Decoding of Overcomplete Expansions Using Projections onto Convex Sets
 In Proceedings of Data Compression Conference
, 1999
"... This paper presents a POCSbased algorithm for consistent reconstruction of a signal x 2 R K from any subset of quantized coefficients y 2 R N in an N \Theta K overcomplete frame expansion y = Fx, N = 2K. By choosing the frame operator F to be the concatenation of two K \Theta K invertible tr ..."
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Cited by 20 (0 self)
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This paper presents a POCSbased algorithm for consistent reconstruction of a signal x 2 R K from any subset of quantized coefficients y 2 R N in an N \Theta K overcomplete frame expansion y = Fx, N = 2K. By choosing the frame operator F to be the concatenation of two K \Theta K invertible transforms, the projections may be computed in R K using only the transforms and their inverses, rather than in the larger space R N using the pseudoinverse as proposed in earlier work. This enables practical reconstructions from overcomplete frame expansions based on wavelet, subband, or lapped transforms of an entire image, which has heretofore not been possible. 1 Introduction Multiple description (MD) source coding is the problem of encoding a single source fX i g into N separate binary descriptions at rates R 1 ; : : : ; RN bits per symbol such that any subset S of the descriptions may be received and together decoded to an expected distortion D S commensurate with the total b...
Average Profile Of The LempelZiv Parsing Scheme For A Markovian Source
 Algorithmica
, 1998
"... For a Markovian source, we analyze the LempelZiv parsing scheme that partitions sequences into phrases such that a new phrase is the shortest phrase not seen in the past. We consider three models: In the Markov Independent model, several sequences are generated independently by Markovian sources, ..."
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Cited by 17 (11 self)
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For a Markovian source, we analyze the LempelZiv parsing scheme that partitions sequences into phrases such that a new phrase is the shortest phrase not seen in the past. We consider three models: In the Markov Independent model, several sequences are generated independently by Markovian sources, and the ith phrase is the shortest prefix of the ith sequence that was not seen before as a phrase (i.e., a prefix of previous (i \Gamma 1) sequences). In the other two models, only a single sequence is generated by a Markovian source. In the second model, for which we coin the name GilbertKadota model, a fixed number of phrases is generated according to the LempelZiv algorithm, thus producing a sequence of a variable (random) length. In the last model, known also as the LempelZiv model, a string of fixed length is partitioned into a variable (random) number of phrases. These three models can be efficiently represented and analyzed by digital search trees that are of interest to other al...
A sensing chair using pressure distribution sensors
 IEEE/ASME TRANSACTIONS ON MECHATRONICS
, 2001
"... One challenge in multimodal interface research is the lack of robust subsystems that support multimodal interactions. By focusing on a chair—an object that is involved in virtually all human–computer interactions, the sensing chair project enables an ordinary office chair to become aware of its occ ..."
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Cited by 17 (1 self)
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One challenge in multimodal interface research is the lack of robust subsystems that support multimodal interactions. By focusing on a chair—an object that is involved in virtually all human–computer interactions, the sensing chair project enables an ordinary office chair to become aware of its occupant’s actions and needs. Surfacemounted pressure distribution sensors are placed over the seatpan and backrest of the chair for real time capturing of contact information between the chair and its occupant. Given the similarity between a pressure distribution map and a grayscale image, pattern recognition techniques commonly used in computer and robot vision, such as principal components analysis, have been successfully applied to solving the problem of sitting posture classification. The current static posture classification system operates in real time with an overall classification accuracy of 96 % and 79 % for familiar (people it had felt before) and unfamiliar users, respectively. Future work is aimed at a dynamic posture tracking system that continuously tracks not only steadystate (static) but transitional (dynamic) sitting postures. Results reported here form important stepping stones toward an intelligent chair that can find applications in many areas including multimodal interfaces, intelligent environment, and safety of automobile operations.