ppxscal/embedding_network huggingface dataset:
Sparse communication networks and efficient routing in the plane (extended abstract)
Authors: Yehuda Hassin, David Peleg
Venue: Proceedings of the nineteenth annual ACM symposium on Principles of distributed computing (2000)

Traditional approaches to network design separate the issues of designing the network itself and designing its management and control subsystems. This paper proposes an approach termed routing-oriented network design, which is based on designing the network topology and its routing scheme together, attempting to optimize some of the relevant parameters of both simultaneously. This approach is explored by considering the design of communication networks supporting efficient routing in the special case of points located in the Euclidean plane. The desirable network parameters considered include low degree and small number of communication links. The desirable routing parameters considered include small routing tables, small number of hops and low routing stretch. Two rather different schemes are presented, one based on direct navigation in the plane and the other based on efficient hierarchical tree covers. On a collection of n sites with diameter D, these methods yield networks with maximum degree O(log D) (hence a total of O(n log D) communication links), coupled with routing schemes with constant routing stretch, O(log n log D) memory bits per vertex and routes with at most log n or log D hops.
MPEG-4 Video and Image Coding on Digital Signal Processors
Authors: Madhukar Budagavi, Jennifer Webb, Minhua Zhou, Jie Liang, Raj Talluri
Venue: Journal of VLSI Signal Processing Systems (1999)

The emerging MPEG-4 standard encompasses a wide variety of applications, many of which are suitable for implementation on a Digital Signal Processor (DSP). In particular, consumer products with embedded multimedia capability, such as set-top boxes and wireless communicators, are suitable for DSP-based implementation. With a programmable approach, various algorithmic tradeoffs can be made, based on processing capability. For best performance, careful attention must be paid to memory allocation, data transfer, and ordering of instructions to best match the DSP architecture. We discuss implementing simple profile MPEG-4 video on the low-power TMS320C54x, core profile on the TMS320C6x, and scalable texture profile, which could be implemented on either processor family.
Three-dimensional in vivo morphometry of trabecular bone in the OVX rat model of osteoporosis
Authors: J. H. Kinney, J. T. Ryaby, D. L. Haupt, N. E. Lane
Venue: Technology and Health Care (1998)

This paper describes the application of synchrotron radiation microtomography to osteoporosis research. By taking advantage of the high intensity, collimation, and monochromaticity of synchrotron radiation, we have been able to image the three-dimensional trabecular bone structure in living rats, thus providing serial data on the earliest architectural changes that occur with estrogen loss. Results from these in vivo animal experiments demonstrate that one of the earliest manifestations of estrogen loss, in addition to a decrease in the amount of trabecular bone, is decreased connectivity. We demonstrate that estrogen replacement therapy, when initiated soon after significant changes have occurred, restores bone mass to baseline levels but does not recover the trabecular connectivity. Even without an associated recovery in trabecular connectivity, finite element calculations on the three-dimensional images suggest that estrogen recovers the original structural modulus of elasticity. We believe the recovery of the elastic properties is due to an increase in trabecular thickness above baseline values.
An organizer for project-based learning and instruction in computer science
Authors: Zahava Scherz, Sarah Polak
Venue: ACM SIGCSE Bulletin (1999)

The computer science (CS) educational community has recently realized the potential of project-based learning (PBL) in CS education. The new CS curriculum for high school students in Israel consists of 3 to 5 courses --- one of which requires a final project instead of the traditional final examination. PBL demands many changes in students' learning habits and requires new instructional methodology. This paper presents the rational and objectives of a PBL organizer that was specifically designed for a project oriented logic programming high school course. The PBL organizer gradually supports both students and teachers in project development processes.
Wavelet Methods for Second-Order Elliptic Problems, Preconditioning, and Adaptivity
Authors: A. Cohen, R. Masson
Venue: SIAM Journal on Scientific Computing (1999)

Wavelet methods allow us to combine high-order accuracy, efficient preconditioning techniques, and adaptive approximations in order to solve efficiently elliptic operator equations. Many difficulties remain, in particular, related to the adaptation of wavelet decompositions to bounded domains with prescribed boundary conditions, leading to possibly high constants in the ${\cal O}(1)$ preconditioning. In this paper we consider the framework of conforming domain decomposition to generate our wavelet bases and second-order operators. We emphasize the choice of the wavelets near the boundary of the tensor product reference domain in order to optimize the efficiency of the diagonal preconditioning of elliptic operators. In order to improve the constants obtained by such diagonal preconditionings, we propose to take into account interactions between the scales through the computation of a sparse approximate inverse (SPAI) on a set of nonzero entries obtained from the compression of the operator itself in the wavelet basis. The efficiency of these methods is illustrated by solving elliptic second-order problems with variable or constant coefficients and homogeneous boundary conditions on a uniform discretization. Finally, we propose a coupling of the iterative solver with an adaptive space refinement technique. On the Laplacian model problem, our experiments show that this algorithm generates an optimal nonlinear approximation of the solution.
A Simple Approximation Algorithm for Two Problems in Circuit Design
Authors: Tamra Carpenter, Steven Cosares, Joseph L. Ganley, Iraj Saniee
Venue: IEEE Transactions on Computers (1998)

This paper provides a very simple two-approximation algorithm for two NP-hard problems that arise in electronic circuit design. To our knowledge, this is the best approximation bound known for these problems. In addition, the simplicity of the proposed algorithm makes it attractive for real-time applications for similar problems in areas such as telecommunications and parallel processing.
Automated disk drive characterization (poster session)
Authors: Jiri Schindler, Gregory R. Ganger
Venue: ACM SIGMETRICS Performance Evaluation Review (2000)

DIXtrac is a program that automatically characterizes the performance of modern disk drives. This extended abstract overviews the contents of [3], which describes and validates DIXtrac's algorithms for extracting accurate values for over 100 performance-critical parameters in 2-6 minutes without human intervention or special hardware support. The extracted data includes detailed layout and geometry information, mechanical timings, cache management policies, and command processing overheads. DIXtrac is validated by configuring a detailed disk simulator with its extracted parameters; in most cases, the resulting accuracies match those of the most accurate disk simulators reported in the literature. To date, DIXtrac has been successfully used on ten different models from four different manufacturers. A growing database of validated disk characteristics is available in DiskSim [1] format at http://www.ece.cmu.edu/~ganger/disksim/diskspecs.html.
Positive Time-Frequency Distributions via Quadratic Programming
Authors: James W. Pitton
Venue: Multidimensional Systems and Signal Processing (1998)

A new method for computing positive time-frequency distributions (TFDs) for nonstationary signals is presented. This work extends the earlier work of the author and his colleagues in computing positive TFDs [8,11]. This paper describes a general quadratic programming approach to the problem of computing these signal-dependent distributions. The method is based on an evolutionary spectrum formulation of positive TFDs. The minimization problem reduces to a linearly-constrained quadratic programming problem, for which standard solutions are widely available.
BDL: A Specialized Language for Per-Object Reactive Control
Authors: Frédéric Bertrand, Michel Augeraud
Venue: IEEE Transactions on Software Engineering (1999)

The problem of describing the concurrent behavior of objects in object-oriented languages is addressed. The approach taken is to let methods be the behavior units whose synchronization is controlled separate from their specification. Our proposal is a domain-specific language, called BDL, for expressing constraints on this control and actually implementing its enforcement. We propose a model where each object includes a so-called ¿execution controller,¿ programmed in BDL. This separates cleanly the concepts of what the methods do, the object processes, from the circumstances in which they are allowed to do it, the control. The object controller ensures that scheduling constraints between the object's methods are met. Aggregate objects can be controlled in terms of their components. This language has a convenient formal base. Thus, using BDL expressions, behavioral properties of objects or groups of interesting objects can be verified. Our approach allows, for example, deadlock detection or verification of safety properties, while maintaining a reasonable code size for the running controller.A compiler from BDL has been implemented, automatically generating controller code in an Esterel program, i.e., in a reactive programming language. From this code, the Esterel compiler, in turn, generates an automaton on which verifications are done. Then this automaton is translated into a C code to be executed. This multistage process typifies the method for successful use of a domain-specific language. This also allows high-level concurrent programming.
Minimizing Total Completion Time in a Two-Machine
Authors: J. A. Hoogeveen, T. Kawaguchi
Venue: Mathematics of Operations Research (1999)

We consider the problem of minimizing total completion time in a two-machine owshop. We present a heuristic with worst-case bound 2&#946;/(&#945; + &#946;), where &#945; and &#946; denote the minimum and maximum processing time of all operations. Furthermore, we analyze four special cases: equal processing times on the first machine, equal processing times on the second machine, processing a job on the first machine takes time no less than its processing on the second machine, and processing a job on the first machine takes time no more than its processing on the second machine. We prove that the rst special case is NP-hard in the strong sense and present an O(n log n) approximation algorithm for it with worst-case bound 4/3. We repeat the easy polynomial algorithms for the cases two and three, and show that problem four is solvable in polynomial time as well.
The nature of end-user relationships in the development of electronic commerce applications
Authors: A. C. Leonard, C. de Villiers
Venue: Proceedings of the 2000 ACM SIGCPR conference on Computer personnel research (2000)

The effectiveness of IT departments, and more specifically the developers of electronic commerce (EC) applications, and the value they are adding to their organizations in many cases are hampered by poor relationships between EC professionals and their end users. This situation impacts on EC professionals' ability to produce service and support of high quality that delivers competitive advantage for the company in the electronic commerce environment. This paper looks into the working relationship between EC developers and its end users. It describes EC-end user relationships as intriguing and complex and that these relationships should be seen and managed as multidimensional entities. Two such dimensions, namely the physical and abstract dimensions which form the basis of EC-end user relationships, enable one to fully describe the holistic nature of such relationships and encapsulate the important elements of a support-oriented organization, namely mutuality, belonging, and connection.
Interactive manipulation of rigid body simulations
Authors: Jovan Popović, Steven M. Seitz Michael Erdmann Zoran Popović Andrew Witkin
Venue: Proceedings of the 27th annual conference on Computer graphics and interactive techniques (2000)

Physical simulation of dynamic objects has become commonplace in computer graphics because it produces highly realistic animations. In this paradigm the animator provides few physical parameters such as the objects' initial positions and velocities, and the simulator automatically generates realistic motions. The resulting motion, however, is difficult to control because even a small adjustment of the input parameters can drastically affect the subsequent motion. Furthermore, the animator often wishes to change the end-result of the motion instead of the initial physical parameters. We describe a novel interactive technique for intuitive manipulation of rigid multi-body simulations. Using our system, the animator can select bodies at any time and simply drag them to desired locations. In response, the system computes the required physical parameters and simulates the resulting motion. Surface characteristics such as normals and elasticity coefficients can also be automatically adjusted to provide a greater range of feasible motions, if the animator so desires. Because the entire simulation editing process runs at interactive speeds, the animator can rapidly design complex physical animations that would be difficult to achieve with existing rigid body simulators.
AQUILA: An Equivalence Checking System for Large Sequential Designs
Authors: Shi-Yu Huang, Kwang-Ting Cheng, Kuang-Chien Chen, Forrest Brewer, Chung-Yang Huang
Venue: IEEE Transactions on Computers (2000)

In this paper, we present a practical method for verifying the functional equivalence of two synchronous sequential designs. This tool is based on our earlier framework that uses Automatic Test Pattern Generation (ATPG) techniques for verification. By exploring the structural similarity between the two designs under verification, the complexity can be reduced substantially. We enhance our framework by three innovative features. First, we develop a local BDD-based technique which constructs Binary Decision Diagram (BDD) in terms of some internal signals, for identifying equivalent signal pairs. Second, we incorporate a technique called partial justification to explore not only combinational similarity, but also sequential similarity. This is particularly important when the two designs have a different number of flip-flops. Third, we extend our gate-to-gate equivalence checker for RTL-to-gate verification. Two major issues are considered in this extension: 1) how to model and utilize the external don't care information for verification; and 2) how to extract a subset of unreachable states to speed up the verification process. Compared with existing approaches based on symbolic Finite State Machine (FSM) traversal techniques, our approach is less vulnerable to the memory explosion problem and, therefore, is more suitable for a lot of real-life designs. Experimental results of verifying designs with hundreds of flip-flops will be presented to demonstrate the effectiveness of this approach.
Query processing techniques for arrays
Authors: Arunprasad P. Marathe, Kenneth Salem
Venue: ACM SIGMOD Record (1999)

Arrays are an appropriate data model for images, gridded output from computational models, and other types of data. This paper describes an approach to array query processing. Queries are expressed in AML, a logical algebra that is easily extended with user-defined functions to support a wide variety of array operations. For example, compression, filtering, and algebraic operations on images can be described. We show how AML expressions involving such operations can be treated declaratively and subjected to useful rewrite optimizations. We also describe a plan generator that produces efficient iterator-based plans from rewritten AML expressions.
Structure Preservation for Constrained Dynamics with Super Partitioned Additive Runge--Kutta Methods
Authors: Laurent O. Jay
Venue: SIAM Journal on Scientific Computing (1998)

A broad class of partitioned differential equations with possible algebraic constraints is considered, including Hamiltonian and mechanical systems with holonomic constraints. For mechanical systems a formulation eliminating the Coriolis forces and closely related to the Euler--Lagrange equations is presented. A new class of integrators is defined: the super partitioned additive Runge--Kutta (SPARK) methods. This class is based on the partitioning of the system into different variables and on the splitting of the differential equations into different terms. A linear stability and convergence analysis of these methods is given. SPARK methods allowing the direct preservation of certain properties are characterized. Different structures and invariants are considered: the manifold of constraints, symplecticness, reversibility, contractivity, dilatation, energy, momentum, and quadratic invariants. With respect to linear stability and structure-preservation, the class of s-stage Lobatto IIIA-B-C-C* SPARK methods is of special interest. Controllable numerical damping can be introduced by the use of additional parameters. Some issues related to the implementation of a reversible variable stepsize strategy are discussed.
Three-Dimensional Human Body Model Acquisition from Multiple Views
Authors: Ioannis A. Kakadiaris, Dimitri Metaxas
Venue: International Journal of Computer Vision (1998)

We present a novel approach to the three-dimensional human body model acquisition from three mutually orthogonal views. Our technique is based on the spatiotemporal analysis of the deforming apparent contour of a human moving according to a protocol of movements. For generality and robustness our technique does not use a prior model of the human body and a prior body part segmentation is not assumed. Therefore, our technique applies to humans of any anthropometric dimension. To parameterize and segment over time a deforming apparent contour, we introduce a new shape representation technique based on primitive composition. The composed deformable model allows us to represent large local deformations and their evolution in a compact and intuitive way. In addition, this representation allows us to hypothesize an underlying part structure and test this hypothesis against the relative motion (due to forces exerted from the image data) of the defining primitives of the composed model. Furthermore, we develop a Human Body Part Decomposition Algorithm (HBPDA) that recovers all the body parts of a subject by monitoring the changes over time to the shape of the deforming silhouette. In addition, we modularize the process of simultaneous two-dimensional part determination and shape estimation by employing the Supervisory Control Theory of Discrete Event Systems. Finally, we present a novel algorithm which selectively integrates the (segmented by the HBPDA) apparent contours from three mutually orthogonal viewpoints to obtain a three-dimensional model of the subject&lsquo;s body parts. The effectiveness of the approach is demonstrated through a series of experiments where a subject performs a set of movements according to a protocol that reveals the structure of the human body.
New algorithms for the duplication-loss model
Authors: M. T. Hallett, J. Lagergren
Venue: Proceedings of the fourth annual international conference on Computational molecular biology (2000)

We consider the problem of constructing a species tree given a number of gene trees. In the frameworks introduced by Goodman et al. [3], Page [10], and Guig&oacute;, Muchnik, and Smith [5] this is formulated as an optimization problem; namely, that of finding the species tree requiring the minimum number of duplications and/ or losses in order to explain the gene trees. In this paper, we introduce the WIDTH k DUPLICATION-LOSS and WIDTH k DUPLICATION problems. A gene tree has width k w.r.t. a species tree, if the species tree can be reconciled with the gene tree using at most k simultaneously active copies of the gene along its branches. We explain w.r.t. to the underlying biological model, why this width is typically very small in comparison to the total number of duplications and losses. We show polynomial time algorithms for finding optimal species trees having bounded width w.r.t. at least one of the input gene trees. Furthermore, we present the first algorithm for input gene trees that are unrooted. Lastly, we apply our algorithms to a dataset from [5] and show a species tree requiring significantly fewer duplications and fewer duplications/losses than the trees given in the original paper.
Element-by-Element Parallel Computation of Incompressible Navier--Stokes Equations in Three Dimensions
Authors: Tony W. H. Sheu, Morten M. T. Wang, S. F. Tsai
Venue: SIAM Journal on Scientific Computing (1999)

Development of a stable finite element model for solving steady incompressible viscous fluid flows in three dimensions is the main theme of the present study. For stability reasons, weighting functions are designed in favor of field variables on the upstream side. For accuracy reasons, it is required that weighting functions be equipped with the streamline operator so that false diffusion errors can be largely suppressed. In the steady-state analysis of Navier--Stokes equations, we adopt the mixed formulation to preserve mass conservation on quadratic elements which accommodate the Ladyzhenskaya--Babuska--Brezzi (LBB) stability condition. To resolve difficulties arising from asymmetry and indefiniteness in the resulting large-size matrix equations, we abandon the elimination-like solution solver because the storage demand exceeds the ability of our hardware to solve for three-dimensional problems. A modern iteration solver, known as the biconjugate gradiant stabilized (BICGSTAB) solution solver, is thus implemented in an element-by-element fashion to effectively alleviate the problem. For performance reasons, the finite element code developed here should be implemented in a hardware environment which is suited to the use of an iterative solver. To this end, our analysis is implemented in shared memory parallel architectures, CRAY C-90 and J-90. We benchmark the parallel computing performance through a lid-driven cavity flow problem and a problem amenable to analytic solution.