ppxscal/embedding_network huggingface dataset:
Design of new Daspk for Sensitivity Analysis
Authors: Shengtai Li, Linda Petzold
Venue:  (1999)

A new version of DASPK, DASPK3.0, with capability for sensitivity analysis is presented in this report. DASPK3.0 differs from the sensitivity code DASPKSO, described in {MaPe96}, in several ways. DASPK3.0 has all the features, which were not available in DASPKSO, of the previous version DASPK2.0. One of these features is an improved algorithm for calculation of consistent initial conditions for index-zero or index-one systems. DASPK3.0 also incorporates a mechanism for initialization and solution of index-2 systems. Other improvements in DASPK3.0 include a more accurate error and convergence test, particularly for the sensitivity analysis. We implemented the Krylov method for sensitivity computation with a different strategy from DASPKSO, and made it more efficient and easier for parallel computing. We also added the staggered corrector method {FeBa97} for both the direct and Krylov method. We implemented the sensitivity analysis with an internal parallel mode, which is easy to use for both serial and parallel computation with message passing interface (MPI). We also incorporated automatic differentiation into DASPK3.0 to evaluate the Jacobian matrix and sensitivity equations. The goal of our design has been to be compatible as much as possible with DASPK2.0, to minimize memory and storage requirements for sensitivity analysis, and to speed up the computation for a large number of sensitivity parameters.
The Elusive Atomic Register
Authors: Ambuj K. Singh, James H. Anderson, Mohamed G. Gouda
Venue:  (1989)

We present two constructions of a multiple-reader atomic register from single-reader atomic registers. The first is a recursive construction; a two-reader construction defines the base step, and a scheme to construct an M-reader register from (M-1)-reader registers defines the induction step. This construction, although simple to understand and verify, has exponential complexity. Our second construction is also an extension of the above two-reader construction. This construction, while more complicated, has optimal complexity; it requires O(M2+MN) atomic single-reader bits for an N-bit register.
Building Robust Distributed Applications With Reflective Transformations
Authors: Anh Nguyen-Tuong, Andrew S. Grimshaw
Venue:  (1997)

Several projects are currently underway to build the nation''s next generation computing infrastructure. These projects are sometimes called metasystems projects and seek to provide the illusion of a single, unified, virtual computing environment to end users. We expect metasystems to consist of millions of hosts and billions of objects, and on this scale, resource failures will be the norm and no longer the exception. One of the technical challenges that must be solved before such systems become usable is the widespread adoption of fault-tolerance techniques for both system level services and user applications. As part of the Legion metasystem project, we have developed an architecture for incorporating fault-tolerance techniques into user applications. Our approach is based on reflective dynamic transformation techniques that manipulate the control and data flow characteristics of an application to achieve the desired fault-tolerance policies. In this paper, we present our Reflective Graph & Event model (RGE) computation model and illustrate sample reflective transformations for incorporating exception handling and replication techniques into applications.
Granularity Issues for Solving Polynomial Systems via Globally Convergent Algorithms on a Hypercube
Authors: Donald C. S. Allison, Amal Chakraborty, Layne T. Watson
Venue:  (1988)

Polynomial systems of equations frequently arise in many applications such as solid modeling, robotics, computer vision, chemistry, chemical engineering, and mechanical engineering . Locally convergent iterative methods such as quasi-Newton methods may diverge or fail to find all meaningful solutions of a polynomial system. Recently a homotopy algorithm has been proposed for polynomial systems that is guaranteed globally convergent (always converges from an arbitrary starting point) with probability one, finds all solutions to the polynomial system, and has a large amount of inherent parallelism. There are several ways the homotopy algorithms can be decomposed to run on a hypercube. The granularity of a decomposition has a profound effect on the performance of the algorithm. The results of decompositions with two different granularities are presented. The experiments were conducted on an iPSC-16 hypercube using actual industrial problems.
FORCE-DRIVEN CONSTRAINED WIRING OPTIMIZATION
Authors: Tal Dayan, Wayne W Dai
Venue:  (1991)

We describe a practical iterative approximation algorithm that can be used for homotopic positioning of Steiner points and vias for minimization of a wiring cost in rubber-band sketches. The algorithm is based on modeling the interconnect as a physical system and iterativly finding it minimum energy state. This method has a wide range of applications including finding Steiner trees, optimization of nets with given topologies, and optimization of constrained nets. It supports multi-layer sketches with obstacles, and can be adapted to various optimization goals by changing the force function. The algorithm can be used to improved the topology or to improve the wiring for a given topology. By controlling, the force functions of the physical system, various aspect of the interconnect such as average or maximal wire length can be improved.
Affine Transformations of the Speech Space
Authors: Mylene Pijpers, Mike Alder
Venue:  (1992)

The papers Speaker Normalization of static and dynamic vowel spectral features (J.A.S.A 90, July 1991 pp 67-75) and Minimum Mean-Square Error Transformations of Categorical Data to Target Positions (IEEE Trans Sig.Proc,40 Jan 1992, pp13-23) by Zahorian and Jagharghi describe an algorithm for transforming the space of speech sounds so as to improve the accuracy of classification. Classification was accomplished by both back-propagation neural nets and by a Bayesian Maximum Likelihood method on the model of each vowel class being specified by a gaussian distribution. The transformation was an affine transformation obtained by choosing ideal `target'' points for each cluster in a second space and minimising the mean square distance of the points in the speech space from the appropriate target. The speech space itself was a space of cepstral coefficients obtained from a Discrete Cosine Transform. These findings are remarkable, indeed almost unbelievable. The reason is that both the maximum likelihood classification on the gaussian model, and the Neural Net classifier are essentially affine invariant. In the case where the transform ation is invertible, this is clearly the case. When the transformation has non-trivial kernel, it may happen that the classification gets worse, but it cannot get better. A back-propagation neural net in effect classifies by dividing the space into regions by means of hyperplanes. The gaussian model does so by means of quadratic forms, with quadratic discrimination hypersurfaces. Projecting a hyperplane by any non-zero affine map which is onto the target space will usually give another hyperplane in the target space, and if the second separates points, so will the first. Conversely, if there is a solution in the target space, it can be pulled back to a solution in the domain space. It is not hard to show that similar considerations apply to the case where we use quadratic hypersurfaces. In this paper, we attempt to account for the results of Zahorian and Jagharghi by investigating vowel data. We describe a simple projection algorithm which may be applied to high dimensional data to give a view on a computer screen of the data and of transformations of it.
Observations on Hot Potato Routing
Authors: U. Feige
Venue:  (1994)

In batch routing problems, processors that are interconnected by a communication network inject packets into the network. Each packet has to be routed to its repspective destination, where at each time step, each communication link can be traversed by at most one packet. In ``hot potato'''' packet routing, packets must keep on moving until they reach their destinations, even if this means temporarily moving further away from their destinations (in contrast to ``store and forward'''' routing, where temporary storage at intermediate locations is allowed). There is experimental evidence that simple hot potato routing algorithms perform well in practice, but rigorously proving reasonably good upper bounds on their performance turns out to be a difficult task. In this paper we investigate some simple design principles for hot potato routing algorithms? The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
HIERARCHICAL RENDERING OF COMPLEX ENVIRONMENTS (Ph.D. Thesis)
Authors: Ned Greene
Venue:  (1995)

We present three related algorithms designed to accelerate rendering of very complex, densely occluded scenes composed of geometric models where surface shading is restricted to local illumination methods. The algorithms share the same basic structure, maintaining hierarchical data structures in both object space and image space to enable finding visible geometry by logarithmic search. To render a scene, the basic algorithm traverses nodes in the object-space hierarchy (an octree) in front-to-back order, testing the bounding volumes of nodes for visibility and culling hidden nodes. Thus, only visible nodes and their children in the hierarchy are visited, and only primitives in visible nodes need to be rendered. This procedure culls most hidden geometry in densely occluded scenes, but some geometry will still overlap on the screen when primitives are projected. To cull remaining hidden geometry, we perform hierarchical culling in image space, using the image-space hierarchy to maintain visibility information about previously rendered geometry. Two of the algorithms, "hierarchical z-buffer visibility" and "hierarchical polygon tiling," have exceptional performance and are appropriate for interactive applications. The hierarchical z-buffer algorithm maintains depth samples in a pyramid, permitting z-buffer depth comparisons to be performed hierarchically, which enables very rapid culling of hidden octree cubes and hidden primitives. Visible primitives are rendered with the speed of traditional incremental scan conversion. The algorithm''s hierarchical culling capabilities make it possible to compute standard z-buffer images of densely occluded scenes much faster than traditional z-buffering. Alternatively, instead of performing visibility operations by z-buffering, the second variation of the basic algorithm employs a novel polygon tiling algorithm to cull hidden octree cubes and tile potentially visible polygons. Called hierarchical polygon tiling, this method traverses scene polygons front to back and performs tiling by Warnock-style recursive subdivision of image space. Visibility information is maintained in an image-space pyramid of coverage masks, which permits subdivision to be driven very efficiently by boolean mask operations. When antialiasing is performed by oversampling and filtering, this tiling algorithm is much faster than hierarchical z-buffering. The third algorithm, "error-bounded antialiased rendering," is much slower than the other two algorithms, but is unique in its ability to produce antialiased images of guaranteed accuracy. This algorithm also culls hidden octree cubes and tiles potentially visible polygons by recursive subdivision of the image-space hierarchy. By using interval methods to control subdivision of image space, the algorithm is able to identify regions where geometry or shading is complex and do as much work as necessary within those regions to produce accurate results. Consequently, each pixel of the output ima
A Novel Storage Scheme for Parallel Jacobi Methods
Authors: Robert A. van de Geijn
Venue:  (1988)

A novel storage scheme is presented that allows efficient parallel implementation of the Jacobi method for symmetric matrices by taking advantage of symmetry. For a fixed number of processors, efficiency approaches 100% as the size of the problem is increased.
Exploiting Spectral, Spatial and Semantic Constraints in the Segmentation of Landsat Images
Authors: Dale Starr, Alan K. Mackworth
Venue:  (1978)

A critique of traditional classification techniques for LANDSAT images and consideration of some scene analysis techniques, exploiting spatial organization and meaning, lead to a new approach to computer programs for LANDSAT image understanding. To justify this approach, a program that combines modified maximum likelihood techniques with interpretation-controlled region merging methods to interpret forest cover in LANDSAT images is described. For comparison purposes, a pure supervised classifier using the same data made 43% more errors and produced a segmentation twice as complex.
3-D to 2-D Pose Determination with Regions
Authors: D. Jacobs, R. Basri
Venue:  (1999)

This paper presents a novel approach to parts-based object recognition in the presence of occlusion. We focus on the problem of determining the pose of a 3-D object from a single 2-D image when convex parts of the object have been matched to corresponding regions in the image. We consider three types of occlusions: self-occlusion, occlusions whose locus is identified in the image, and completely arbitrary occlusions. We show that in the first two cases this is a convex optimization problem, derive efficient algorithms, and characterize their performance. For the last case, we prove that the problem of finding valid poses is computationally hard, but provide an efficient, approximate algorithm. This work generalizes our previous work on region-based object recognition, which focused on the case of planar models.
A STUDY OF THE RELIABILITY OF HOSTS ON THE INTERNET (Masters Thesis)
Venue:  (1993)

This thesis is a study of the failure statistics of hosts on the Internet. To cross-verify our estimates of failure rates, we measure three different kinds of observations about hosts on the Internet - the time interval between failure, the number of failures in a certain time interval, and the length of time a host has been up at an arbitrary instant of time. These observations are made on different samples of hosts on the Internet. We present statistical results that allow us to derive estimates about the failure statistics of the population from these three different types of observations. The estimates from the three experiments are slightly different but comparable, providing three independent sources of evidence about the failure statistics of hosts on the Internet. We also attempt to explain the observations by modeling the statistical process with two distributions - the exponential and Weibull distribution. The observed data are explained well (in a statistical sense) by both models, but the Weibull model fits the observed sample better. We believe this to be evidence that the failure rates of hosts on the Internet are nearly constant, but with a high initial value that quickly decreases to a constant as the machine continues to run. The ACM Portal is published by the Association for Computing Machinery. Copyright © 2010 ACM, Inc. Terms of Usage Privacy Policy Code of Ethics Contact Us Useful downloads: Adobe Acrobat QuickTime Windows Media Player Real Player
Analysis of Function Component Complexity for Hypercube HomotopyAlgorithms
Authors: Amal Chakraborty, Donald C. S. Allison, Calvin J. Ribbens, Layne T. Watson
Venue:  (1990)

Probability-one homotopy algorithms are a class of methods for solving nonlinear systems of equations that globally convergent from an arbitrary starting point with probability one. The essence of these homotopy algorithms is the construction of a homotopy map p-sub a and the subsequent tracking of a smooth curve y in the zero set p-sub a to the -1 (0) of p-sub a. Tracking the zero curve y requires repeated evaluation of the map p-sub a, its n x (v + 1) Jacobian matrix Dp-sub a and numerical linear algebra for calculating the kernel of Dp-sub a. This paper analyzes parallel homotopy algorithms on a hypercube, considering the numerical algebra, several communications topologies and problem decomposition strategies, functions component complexity, problem size, and the effect of different component complexity distributions. These parameters interact in complicated ways, but some general principles can be inferred based on empirical results.
Finding the story: broader applicability of semantics and discourse for hypermedia generation
Authors: Lloyd Rutledge, Martin Alberink, Rogier Brussee, Stanislav Pokraev, William van Dieten, Mettina Veenstra
Venue: Proceedings of the fourteenth ACM conference on Hypertext and hypermedia (2003)

Generating hypermedia presentations requires processing constituent material into coherent, unified presentations. One large challenge is creating a generic process for producing hypermedia presentations from the semantics of potentially unfamiliar domains. The resulting presentations must both respect the underlying semantics and appear as coherent, plausible and, if possible, pleasant to the user. Among the related unsolved problems is the inclusion of discourse knowledge in the generation process. One potential approach is generating a discourse structure derived from generic processing of the underlying domain semantics, transforming this to a structured progression and then using this to steer the choice of hypermedia communicative devices used to convey the actual information in the resulting presentation.This paper presents the results of the first phase of the Topia project, which explored this approach. These results include an architecture for this more domain-independent processing of semantics and discourse into hypermedia presentations. We demonstrate this architecture with an implementation using Web standards and freely available technologies.
Performance of Some Local Area Network Technologies
Authors: Samuel T. Chanson, A. Kumar, A. Nadkarni
Venue:  (1982)

This paper classifies local area network (LAN) technologies according to their topology and access method. The characteristics of the popular LAN technologies (namely Ring/Token passing, Ring/Message slots and Bus/Contention) are discussed. Analytic models are developed to estimate the mean packet delay time of each technology as a function of the network loading for various packet sizes and number of active stations. It is found that in the case of slotted rings (but not the other two technologies) an optimal value of the number of active stations exists which minimizes the mean delay time at all load levels given a packet arrival rate. The LAN technologies are compared with regard to their performance, reliability, availability, maintainability, extensibility, fairness and complexity. .br It is hoped that potential users may be able to select the appropriate technology for their intended applications based or their specific performance requirements and operation environment. As well, LAN designers may benefit from the insight provided with the analysis.
Supersonic Flows of Dense Gases in Cascade Configurations
Authors: J. F. Monaco, Mark S. Cramer, Layne T. Watson
Venue:  (1995)

We examine the steady, inviscid, supersonic flow of Bethe-Zel''dovich-Thompson (BZT) fluids in two-dimensional cascade configurations. Bethe-Zel''dovich-Thompson fluids are single-phase gases having specific heats so large that the fundamental derivative of gasdynamics is negative over a finite range of pressures and temperatures. The equation of state is the well-known Martin-Hou equation, and the numerical scheme is the explicit predictor-corrector method of MacCormack. Numerical comparisons between BZT fluids and lighter fluids such as steam are presented. It was found that the natural dynamics of BZT fluids can result in significant reductions in the adverse pressure gradients associated with the collision of compression waves with neighboring turbine blades. A numerical example of an entirely isentropic supersonic cascade flow is also presented.
A Framework for Precise, Reusable Task Abstractions
Authors: H. R Hartson, Kevin A. Mayo
Venue:  (1994)

This paper is about modeling human-computer interaction for better understanding of interaction, leading to better designs and design representations. We argue for a structured approach to task abstractions that includes semantics, as well as a framework and vocabulary for abstraction. Our approach imposes a notational consistency that aids designer-implementer communication. Including semantic considerations allows designers to specify interaction so that implementers can properly support the connection between illusion and reality.
Some Experiments on the Sorting by Reversals Method
Authors: Lenwood S. Heath, John P Vergara
Venue:  (1995)

Sorting by reversals is the problem of finding the minimum number of reversals required to sort a permutation pi. The problem is significant with respect to the study of genome rearrangements and phylogeny reconstruction. This paper presents a programming framework for performing experiments on the problem. Several conjectures concerning optimal sorting sequences are tested using this framework.
Fixed-Priority Scheduling of Periodic Tasks on Multiprocessor Systems
Authors: Yingfeng Oh, Sang H. Son
Venue:  (1995)

Consider the problem of periodic task scheduling, in which we seek to minimize the total number of processors required to execute a set of tasks such that task deadlines are guaranteed by the Rate-Monotonic (or RM) algorithm on each processor. This problem was first investigated by Dhall and Liu, and the previous lowest bound for the problem was 2.0. In this paper, an improved solution is given by designing a new algorithm for it. The algorithm, called RM-First-Fit-Decreasing-Utilization (or RM-FFDU), is shown to have a worst-case tight bound of 5/3 = 1.66..., the lowest upper bound ever derived for the scheduling problem. Simulation studies show that on the average, the new algorithm performs consistently better than those in the literature.