ppxscal/embedding_network huggingface dataset:
Mixed Covolume Methods for Elliptic Problems on Triangular Grids
Authors: So-Hsiang Chou, Do Y. Kwak, Panayot S. Vassilevski
Venue: SIAM Journal on Numerical Analysis (1998)

We consider a covolume or finite volume method for a system of first-order PDEs resulting from the mixed formulation of the variable coefficient-matrix Poisson equation with the Neumann boundary condition. The system may represent either the Darcy law and the mass conservation law in anisotropic porous media flow, or Fourier law and energy conservation. The velocity and pressure are approximated by the lowest order Raviart--Thomas space on triangles. We prove its first-order optimal rate of convergence for the approximate velocities in the $L^2$-and $H(\mbox{div};\Omega)$-norms as well as for the approximate pressures in the $L^2$-norm. Numerical experiments are included.
Efficient and cost-effective techniques for browsing and indexing large video databases
Authors: JungHwan Oh, Kien A. Hua
Venue: ACM SIGMOD Record (2000)

We present in this paper a fully automatic content-based approach to organizing and indexing video data. Our methodology involves three steps: Step 1: We segment each video into shots using a Camera-Tracking technique. This process also extracts the feature vector for each shot, which consists of two statistical variances VarBA and VarOA. These values capture how much things are changing in the background and foreground areas of the video shot. Step 2: For each video, We apply a fully automatic method to build a browsing hierarchy using the shots identified in Step 1. Step 3: Using the VarBA and VarOA values obtained in Step 1, we build an index table to support a variance-based video similarity model. That is, video scenes/shots are retrieved based on given values of VarBA and VarOA. The above three inter-related techniques offer an integrated framework for modeling, browsing, and searching large video databases. Our experimental results indicate that they have many advantages over existing methods.
Bridging physical and virtual worlds with electronic tags
Authors: Roy Want, Kenneth P. Fishkin, Anuj Gujar, Beverly L. Harrison
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems: the CHI is the limit (1999)

The role of computers in the modern office has divided our activities between virtual interactions in the realm of the computer and physical interactions with real objects within the traditional office infrastructure. This paper extends previous work that has attempted to bridge this gap, to connect physical objects with virtual representations or computational functionality, via various types of tags. We discuss a variety of scenarios we have implemented using a novel combination of inexpensive, unobtrusive and easy to use RFID tags, tag readers, portable computers and wireless networking. This novel combination demonstrates the utility of invisibly, seamlessly and portably linking physical objects to networked electronic services and actions that are naturally associated with their form.
Put that where? voice and gesture at the graphics interface
Authors: Mark Billinghurst
Venue: ACM SIGGRAPH Computer Graphics (1998)

A person stands in front of a large projection screen on which is shown a checked floor. They say, "Make a table," and a wooden table appears in the middle of the floor."On the table, place a vase," they gesture using a fist relative to palm of their other hand to show the relative location of the vase on the table. A vase appears at the correct location."Next to the table place a chair." A chair appears to the right of the table."Rotate it like this," while rotating their hand causes the chair to turn towards the table."View the scene from this direction," they say while pointing one hand towards the palm of the other. The scene rotates to match their hand orientation.In a matter of moments, a simple scene has been created using natural speech and gesture. The interface of the future? Not at all; Koons, Thorisson and Bolt demonstrated this work in 1992 [23]. Although research such as this has shown the value of combining speech and gesture at the interface, most computer graphics are still being developed with tools no more intuitive than a mouse and keyboard. This need not be the case. Current speech and gesture technologies make multimodal interfaces with combined voice and gesture input easily achievable. There are several commercial versions of continuous dictation software currently available, while tablets and pens are widely supported in graphics applications. However, having this capability doesn't mean that voice and gesture should be added to every modeling package in a haphazard manner. There are numerous issues that must be addressed in order to develop an intuitive interface that uses the strengths of both input modalities.In this article we describe motivations for adding voice and gesture to graphical applications, review previous work showing different ways these modalities may be used and outline some general interface guidelines. Finally, we give an overview of promising areas for future research. Our motivation for writing this is to spur developers to build compelling interfaces that will make speech and gesture as common on the desktop as the keyboard and mouse.
Modelling of a Utility Boiler Using Parallel Computing
Authors: P. J. Coelho, P. A. Novo, M. G. Carvalho
Venue: The Journal of Supercomputing (1999)

A mathematical model for the simulation of the turbulent reactive flow and heat transfer in a power station boiler has been parallelized. The mathematical model is based on the numerical solution of the governing equations for mass, momentum, energy and transport equations for the scalar quantities. The k-&epsiv; model and the conserved scalar/prescribed probability density function formalism are employed. Radiative heat transfer is calculated using the discrete ordinates method. The code has been fully parallelized using the spatial domain decomposition approach and MPI. Calculations were performed using an IBM-SP2. It is shown that the computational requirements are reduced and the parallel efficiency increases if the mean temperature and density are calculated a priori, and stored. The role of the different parts of the code on the parallel performance is discussed. A speedup of 5.9 is achieved using 8 processors.
Linear Differential Algorithm for Motion Recovery: AGeometric Approach
Authors: Yi Ma, Jana Košecká, Shankar Sastry
Venue: International Journal of Computer Vision (2000)

The aim of this paper is to explore a linear geometric algorithm for recovering the three dimensional motion of a moving camera from image velocities. Generic similarities and differences between the discrete approach and the differential approach are clearly revealed through a parallel development of an analogous motion estimation theory previously explored in Vieville, T. and Faugeras, O.D. 1995. In Proceedings of Fifth International Conference on Computer Vision, pp. 750&ndash;756&semi; Zhuang, X. and Haralick, R.M. 1984. In Proceedings of the First International Conference on Artificial Intelligence Applications, pp. 366&ndash;375. We present a precise characterization of the space of differential essential matrices, which gives rise to a novel eigenvalue-decomposition-based 3D velocity estimation algorithm from the optical flow measurements. This algorithm gives a unique solution to the motion estimation problem and serves as a differential counterpart of the well-known SVD-based 3D displacement estimation algorithm for the discrete case. Since the proposed algorithm only involves linear algebra techniques, it may be used to provide a fast initial guess for more sophisticated nonlinear algorithms (Ma et al., 1998c. Electronic Research Laboratory Memorandum, UC Berkeley, UCB/ERL(M98/37)). Extensive simulation results are presented for evaluating the performance of our algorithm in terms of bias and sensitivity of the estimates with respect to different noise levels in image velocity measurements.
Five Steps to Construct a Model of Data Allocation for Distributed Database Systems
Authors: Nadeem H. Daudpota
Venue: Journal of Intelligent Information Systems (1998)

The allocation of data to nodes in a computer communications network is a critical issue in distributed database design, specially in wide area network where optimizing the distributed queries is the main objective. Numerous models of data allocation have been presented so far (Ceri and Pelagatti, 1986; Lee et al., 1994; Apers, 1988; Mahmood et al., 1994; Theel, 1994; Saha and Mukherjee, 1994; Walfson and Jajodia, 1995), but no optimal or universally accepted algorithm exists yet, and very few algorithms have been implemented to date (Rob and Cornonel, 1993). In this paper a method to construct a model of data allocation for distributed database system has been proposed. The adopted method for the construction of the data allocation model leads to an efficient model of its kind. The proposed model not only solves distributed database design problem, but also solves distributed database maintenance problem by covering initial allocation and post allocation of the data. The efficiency of proposed model has been proved by comparing proposed model with other relevant models.
Convergence Results for the Flux Identification in a Scalar Conservation Law
Authors: François James, Mauricio Sepúlveda
Venue: SIAM Journal on Control and Optimization (1999)

Here we study an inverse problem for a quasilinear hyperbolic equation. We start by proving the existence of solutions to the problem which is posed as the minimization of a suitable cost function. Then we use a Lagrangian formulation in order to formally compute the gradient of the cost function introducing an adjoint equation. Despite the fact that the Lagrangian formulation is formal and that the cost function is not necessarily differentiable, a viscous perturbation and a numerical approximation of the problem allow us to justify this computation. When the adjoint problem for the quasi-linear equation admits a smooth solution, then the perturbed adjoint states can be proved to converge to that very solution. The sequences of gradients for both perturbed problems are also proved to converge to the same element of the subdifferential of the cost function. We evidence these results for a large class of numerical schemes and particular cost functions which can be applied to the identification of isotherms for conservation laws modeling distillation or chromatography. They are illustrated by numerical examples.
Designing a children's digital library with and for children
Authors: Yin Leng Theng, Norliza Mohd-Nasir, Harold Thimbleby, George Buchanan, Matthew Jones
Venue: Proceedings of the fifth ACM conference on Digital libraries (2000)

This paper describes preliminary work carried out to design a children's digital library of stories and poems with and for children aged 11-14 years old. We describe our experience in engaging children as design partners, and propose a digital library environment and design features to provide an engaging, successful learning experience for children using it for collaborative writing.
The Regular Fourier Matrices and Nonuniform Fast Fourier Transforms
Authors: Nhu Nguyen, Qing Huo Liu
Venue: SIAM Journal on Scientific Computing (1999)

For any triple of positive integers (m,N,q), the matrix F(m,N,q), called the (m,N,q)-regular Fourier matrix, is defined. The regular Fourier matrices F(m,N,q) are then applied to set up new algorithms for nonuniform fast Fourier transforms. Numerical results show that the accuracies obtained by our algorithms are much better than previously reported results with the same computation complexity. The algorithms require $O(N\cdot\log_2N)$ arithmetic operations, where N is the number of data points.
Keystroke level analysis of email message organization
Authors: Olle Bälter
Venue: Proceedings of the SIGCHI conference on Human factors in computing systems (2000)

Organization of email messages takes an increasing amount of time for many email users. Research has demonstrated that users develop very different strategies to handle this organization. In this paper, the relationship between the different organization strategies and the time necessary to use a certain strategy is illustrated by a mathematical model based on keystroke-level analysis. The model estimates time usage for archiving and retrieving email messages for individual users. Besides explaining why users develop different strategies to organize email messages, the model can also be used to advise users individually when to start using folders, clean messages, learn the search functionality, and using filters to store messages. Similar models could assist evaluation of different interface designs where the number of items increase with time.
BOAT&mdash;optimistic decision tree construction
Authors: Johannes Gehrke, Venkatesh Ganti, Raghu Ramakrishnan, Wei-Yin Loh
Venue: ACM SIGMOD Record (1999)

Classification is an important data mining problem. Given a training database of records, each tagged with a class label, the goal of classification is to build a concise model that can be used to predict the class label of future, unlabeled records. A very popular class of classifiers are decision trees. All current algorithms to construct decision trees, including all main-memory algorithms, make one scan over the training database per level of the tree. We introduce a new algorithm (BOAT) for decision tree construction that improves upon earlier algorithms in both performance and functionality. BOAT constructs several levels of the tree in only two scans over the training database, resulting in an average performance gain of 300% over previous work. The key to this performance improvement is a novel optimistic approach to tree construction in which we construct an initial tree using a small subset of the data and refine it to arrive at the final tree. We guarantee that any difference with respect to the &ldquo;real&rdquo; tree (i.e., the tree that would be constructed by examining all the data in a traditional way) is detected and corrected. The correction step occasionally requires us to make additional scans over subsets of the data; typically, this situation rarely arises, and can be addressed with little added cost. Beyond offering faster tree construction, BOAT is the first scalable algorithm with the ability to incrementally update the tree with respect to both insertions and deletions over the dataset. This property is valuable in dynamic environments such as data warehouses, in which the training dataset changes over time. The BOAT update operation is much cheaper than completely rebuilding the tree, and the resulting tree is guaranteed to be identical to the tree that would be produced by a complete re-build.
Classroom Note: A Note on the Matrix Exponential
Authors: Eduardo Liz
Venue: SIAM Review (1998)

This note is devoted to simplifying one method to calculate the exponential of a matrix presented by I. E. Leonard in [SIAM Rev., 38 (1996), pp. 507--512].
A General Decomposition Construction for Incomplete SecretSharing Schemes
Authors: Marten Van Dijk, Wen-Ai Jackson, Keith M. Martin
Venue: Designs, Codes and Cryptography (1998)

A secret sharing scheme for an incomplete access structure (\G,\D) is a method of distributing information about a secret among a group of participants in such a way that sets of participants in \G can reconstruct the secret and sets of participants in \D can not obtain any new information about the secret. In this paper we present a more precise definition of secret sharing schemes in terms of information theory, and a new decomposition theorem. This theorem generalizes previous decomposition theorems and also works for a more general class of access structures. We demonstrate some applications of the theorem.
Computational Vision at Yale
Authors: Peter N. Belhumeur, James S. Duncan, Gregory D. Hager, Drew V. Mcdermott, A. Stephen Morse, Steven W. Zucker
Venue: International Journal of Computer Vision (1999)

We present a brief introduction to the five articles that make up this special issue: Shock Graphs and Shape Matching, The Bas-Relief Ambiguity, Incremental Focus of Attention for Robust Vision Based Tracking, What Tasks can be Performed with an Uncalibrated Stereo Vision System, and Volumetric Deformation Analysis Using Mechanics-Based Data Fusion: Application in Cardiac Motion Recovery. Tjis introduction and accompanying articles provide a by no means exhaustive, but hopefully representative sampling of the computational vision at Yale University.
Conservative visibility preprocessing using extended projections
Authors: Frédo Durand, George Drettakis, Joëlle Thollot, Claude Puech
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Visualization of very complex scenes can be significantly accelerated using occlusion culling. In this paper we present a visibility preprocessing method which efficiently computes potentially visible geometry for volumetric viewing cells. We introduce novel extended projection operators, which permits efficient and conservative occlusion culling with respect to all viewpoints within a cell, and takes into account the combined occlusion effect of multiple occluders. We use extended projection of occluders onto a set of projection planes to create extended occlusion maps; we show how to efficiently test occludees against these occlusion maps to determine occlusion with respect to the entire cell. We also present an improved projection operator for certain specific but important configurations. An important advantage of our approach is that we can re-project extended projections onto a series of projection planes (via an occlusion sweep), and accumulate occlusion information from multiple blockers. This new approach allows the creation of effective occlusion maps for previously hard-to-treat scenes such as leaves of trees in a forest. Graphics hardware is used to accelerate both the extended projection and reprojection operations. We present a complete implementation demonstrating significant speedup with respect to view-frustum culling only, without the computational overhead of on-line occlusion culling.
The Network Management Wars Have Barely Just Begun
Authors: Ronald C. Sander
Venue: International Journal of Network Management (1996)

Network management is tough. And it is going to quickly get tougher. Countless new distributed mission-critical network applications are fast approaching. The average message size will explode with imaging, virtual reality, groupware, multimedia voice, animation, BLOBs &lpar;Binary Large Objects&rpar; and CAD components. Backbone transmission capacity must increase exponentially and be available as an interchangeable commodity.
Controllable and Autonomous nD Linear Systems
Authors: Jeferry Wood Eric Rogers, David Owens
Venue: Multidimensional Systems and Signal Processing (1999)

The theory of multidimensional systems suffers in certain areas from a lack of development of fundamental concepts. Using the behavioural approach, the study of linear shift-invariant nD systems can be encompassed within the well-established framework of commutative algebra, as previously shown by Oberst. We consider here the discrete case. In this paper, we take two basic properties of discrete nD systems, controllability and autonomy, and show that they have simple algebraic characterizations. We make several non-trivial generalizations of previous results for the 2D case. In particular we analyse the controllable--autonomous decomposition and the controllable subsystem of autoregressive systems. We also show that a controllable nD subsystem of (k^q)^{(\Ints^n)} is precisely one which is minimal in its transfer class.
Fully-Depleted SOI CMOS Technology for Low-Voltage Low-Power Mixed Digital/Analog/Microwave Circuits
Authors: D. Flandre, J. P. Colinge, J. Chen, D. De Ceuster, J. P. Eggermont, L. Ferreira, B. Gentinne, P. G. A. Jespers, A. Viviani, R. Gillon, J. P. Raskin, A. Vander Vorst, D. Vanhoenacker-Janvier, F. Silveira
Venue: Analog Integrated Circuits and Signal Processing (1999)

This paper demonstrates that fully-depleted (FD) silicon-on-insulator (SOI) technology offers unique opportunities in the field of low-voltage, low-power CMOS circuits. Beside the well-known reduction of parasitic capacitances due to dielectric isolation, FD SOI MOSFETs indeed exhibit near-ideal body factor, subthreshold slope and current drive. These assets are both theoretically and experimentally investigated. Original circuit studies then show how a basic FD SOI CMOS process allows for the mixed fabrication and operation under low supply voltage of analog, digital and microwave components with properties significantly superior to those obtained on bulk CMOS. Experimental circuit realizations support the analysis.
Interconnect parasitic extraction in the digital IC design methodology
Authors: Mattan Kamon, Steve McCormick, Ken Sheperd
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

Accurate interconnect analysis has become essential not only for post-layout verification but also for synthesis. This tutorial explores interconnect analysis and extraction methodology on three levels: coarse extraction to guide synthesis, detailed extraction for full-chip analysis, and full 3D analysis for critical nets. We will also describe the electrical issues caused by parasitics and how they have, and will be, influenced by changing technology. The importance of model order reduction will be described as well as methodologies at the synthesis stage for avoiding parasitic problems.
ADEPT: an agent-based approach to business process management
Authors: N. R. Jennings, T. J. Norman, P. Faratin
Venue: ACM SIGMOD Record (1998)

Successful companies organise and run their business activities in an efficient manner. Core activities are completed on time and within specified resource constraints. However to stay competitive in today's markets, companies need to continually improve their efficiency &mdash; business activities need to be completed more quickly, to higher quality and at lower cost. To this end, there is an increasing awareness of the benefits and potential competitive advantage that well designed business process management systems can provide. In this paper we argue the case for an agent-based approach: showing how agent technology can improve efficiency by ensuring that business activities are better scheduled, executed, monitored, and coordinated.
Analyses, Development, and Applications of TLS Algorithms in Frequency Domain System Identification
Authors: Rik Pintelon, Patrick Guillaume, Gerd Vandersteen, Yves Rolain
Venue: SIAM Journal on Matrix Analysis and Applications (1998)

This paper gives an overview of frequency domain total least squares (TLS) estimators for rational transfer function models of linear time-invariant multivariable systems. The statistical performance of the different approaches are analyzed through their equivalent cost functions. Both generalized and bootstrapped total least squares (GTLS and BTLS) methods require the exact knowledge of the noise covariance matrix. The paper also studies the asymptotic (the number of data points going to infinity) behavior of the GTLS and BTLS estimators when the exact noise covariance matrix is replaced by the sample noise covariance matrix obtained from a (small) number of independent data sets. Even if only two independent repeated observations are available, it is shown that the estimates are still strongly consistent without any increase in the asymptotic uncertainty.