ppxscal/embedding_network huggingface dataset:
Three-Dimensional Image Reconstruction Procedure forFood Microstructure Evaluation
Authors: K. Ding, S. Gunasekaran
Venue: Artificial Intelligence Review (1998)

Confocal laser scanning microscopy (CLSM) is a noninvasive technique for evaluating the microstructure of foods and other materials. CLSM provides several sequential subsurface layers of two-dimensional (2-D) images. An image processing algorithm was developed to reconstruct these 2-D layers into a three-dimensional (3-D) network. Microstructure of fat globules in cheese was used as an example application. The validity of the image reconstruction algorithm was evaluated by processing several layered digital images of known shape and size. Differences between the original and reconstructed images were 2&ndash;5% in terms of object size and 1&ndash;8% in terms of shape.
An interactive learning system visualizing computer graphics algorithms
Authors: Achim W. Janser
Venue: Proceedings of the 2nd conference on Integrating technology into computer science education (1997)

At our universities the integration of computers into the classical lectures becomes more and more important, because their usage improves the quality of teaching. Our learning system is concerned with the visualization of Computer Graphics Algorithms. Such an algorithm can hardly be taught on a blackboard or an overhead, because the dynamic and the changes during its execution cannot be illustrated properly on a static display. In a learning system the algorithm can be visualized by using sample outputs that develop stepwise during the execution and by showing the most important variables with their values changing after certain commands. Our learning system is aimed to be used in addition to a classical lecture and practice.
A new approach to simultaneous buffer insertion and wire sizing
Authors: Chris C. N. Chu, D. F. Wong
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

In this paper, we present a completely new approach to the problem of delay minimization by simultaneous buffer insertion and wire sizing for a wire. We show that the problem can be formulated as a convex quadratic program, which is known to be solvable in polynomial time. Nevertheless, we explore some special properties of our problem and derive an optimal and very efficient algorithm to solve the resulting program. Given m buffers and a set of n discrete choices of wire width, the running time of our algorithm is O(mn^2) and is independent of the wire length in practice. For example, an instance of 100 buffers and 100 choices of wire width can be solved in 3 seconds. Besides, our formulation is so versatile that it is easy to consider other objectives like wire area or power dissipation, or to add constraints to the solution. Also, wire capacitance lookup tables, or very general wire capacitance models which can capture area capacitance, fringing capacitance, coupling capacitance, etc. can be used.
Hierarchical Basis Preconditioners in Three Dimensions
Authors: Maria Elizabeth G. Ong
Venue: SIAM Journal on Scientific Computing (1997)

This paper presents hierarchical basis preconditioners for symmetric positive definite linear systems arising from the finite element discretization of second-order elliptic problems in three dimensions. The problem is discretized using nodal basis functions, and the preconditioner arises from a transformation to hierarchical basis functions. For the case where tetrahedral elements and quasi-uniform refinement are used, the condition number of the linear hierarchical basis coefficient matrix $\hat{A}$ preconditioned by a coarse grid operator is $O(h^{-1} \log h^{-1})$, where $h$ is the mesh size. If additional diagonal scaling by levels is applied in the fine grid, a condition number of $O(h^{-1})$ is obtained. The same result is obtained if $\hat{A}$ is preconditioned by its block diagonal. Moreover, any other block diagonal preconditioning of $\hat{A}$ will yield a condition number that grows at least as $O(h^{-1})$. These results compare favorably with the condition number of $O(h^{-2})$ of the nodal coefficient matrix. Numerical results that illustrate the theory are provided. The sequential implementation of this preconditioner in three dimensions using tetrahedral elements takes only $4n$ operations per iteration, where $n$ is the number of unknowns.
Division-Based Analysis of Symmetry and Its Application
Authors: Shigehiro Fukushima
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1997)

A computational method, DAS, is proposed for symmetry analysis of a planar figure closed by a simply connected curve. DAS determines both the symmetric axis and the symmetric point pairs on the curve, consistently, based on the duality of two geometric plane divisions, the Delaunay triangulation and the Voronoi diagram.
Women in introductory computer science: experience at Victoria University of Wellington
Authors: Judy Brown, Peter Andreae, Robert Biddle, Ewan Tempero
Venue: ACM SIGCSE Bulletin (1997)

This paper documents efforts that the department has made to support women students between 1991 and the 1996. Our major goal has been to reduce the high withdrawal rate of women students in our entry level course in computer science. We describe the approaches that have been taken to address this concern, and present the data which has been collected to track the results of our efforts. Our data suggests that providing a gender neutral content is not enough to ensure that men and women will retain similarly. In this paper we suggest policies which we feel may be beneficial in achieving similar male and female retention rates.
Generalized Reflexive Matrices: Special Properties and Applications
Authors: Hsin-Chu Chen
Venue: SIAM Journal on Matrix Analysis and Applications (1998)

The main purpose of this paper is to introduce and exploit special properties of two special classes of rectangular matrices A and B that have the relations A = PAQ {\rm and} B = -PBQ, \qquad A, B \in {\cal C}^{n \times m}, where P and Q are two generalized reflection matrices. The matrices A (B), a generalization of reflexive (antireflexive) matrices and centrosymmetric matrices, are referred to in this paper as generalized reflexive (antireflexive) matrices.After introducing these two classes of matrices and developing general theories associated with them, we then show how to use some of the important properties to decompose linear least-squares problems whose coefficient matrices are generalized reflexive into two smaller and independent subproblems. Numerical examples are presented to demonstrate their usefulness.
A bounds inference method for vector-based memoization
Authors: Wei-Ngan Chin, Masami Hagiya
Venue: ACM SIGPLAN Notices (1997)

The dynamic-sized tabulation method can be used to eliminate redundant calls for certain classes of recursive programs. An innovative aspect of the method is the use of lambda abstractions that may subsequently be converted to bounded vectors, in order to share redundant calls via vector lookup.To facilitate this conversion to vector form, we propose a new inference method to conservatively determine the bounds for arithmetic parameters of recursive functions. Suitable techniques for inferring the safe bounds of these parameters are introduced, together with supporting transformations. The resulting method can obtain efficient vector-based programs without the need for run-time bounds checking.
The Performance of the Cedar Multistage Switching Network
Authors: Josep Torrellas, Zheng Zhang
Venue: IEEE Transactions on Parallel and Distributed Systems (1997)

While multistage switching networks for vector multiprocessors have been studied extensively, detailed evaluations of their performance are rare. Indeed, analytical models, simulations with pseudosynthetic loads, studies focused on average-value parameters, and measurements of networks disconnected from the machine, all provide limited information. In this paper, instead, we present an in-depth empirical analysis of a multistage switching network in a realistic setting: We use hardware probes to examine the performance of the omega network of the Cedar shared-memory machine executing real applications. The machine is configured with 16 vector processors.The analysis suggests that the performance of multistage switching networks is limited by traffic nonuniformities. We identify two major nonuniformities that degrade Cedar's performance and are likely to slow down other networks too. The first one is the contention caused by the return messages in a vector access as they converge from the memories to one processor port. This traffic convergence penalizes vector reads and, more importantly, causes tree saturation. The second nonuniformity is the uneven contention delays induced by a relatively fair scheme to resolve message collisions. Based on our observations, we argue that intuitive optimizations for multistage switching networks may not be the most cost-effective ones. Instead, we suggest changes to increase the network bandwidth at the root of the traffic convergence tree and to delay traffic convergence up until the final stages of the network.
Image Processing with Complex Daubechies Wavelets
Authors: Jean-Marc Lina
Venue: Journal of Mathematical Imaging and Vision (1997)

Analyses based on Symmetric Daubechies Wavelets (SDW) lead to complex-valued multiresolution representations of real signals. After a recall of the construction of the SDW, we present some specific properties of these new types of Daubechies wavelets. We then discuss two applications in image processing: enhancement and restoration. In both cases, the efficiency of this multiscale representation relies on the information encoded in the phase of the complex wavelet coefficients.
Cubetree: organization of and bulk incremental updates on the data cube
Authors: Nick Roussopoulos
Venue: Proceedings of the 1997 ACM SIGMOD international conference on Management of data (1997)

The data cube is an aggregate operator which has been shown to be very powerful for On Line Analytical Processing (OLAP) in the context of data warehousing. It is, however, very expensive to compute, access, and maintain. In this paper we define the &ldquo;cubetree&rdquo; as a storage abstraction of the cube and realize in using packed R-trees for most efficient cube queries. We then reduce the problem of creation and maintenance of the cube to sorting and bulk incremental merge-packing of cubetrees. This merge-pack has been implemented to use separate storage for writing the updated cubetrees, therefore allowing cube queries to continue even during maintenance. Finally, we characterize the size of the delta increment for achieving good bulk update schedules for the cube. The paper includes experiments with various data sets measuring query and bulk update performance.
Coarse-Grained Parallel Algorithms for Multi-DimensionalWavelet Transforms
Authors: Linda Yang, Manavendra Misra
Venue: The Journal of Supercomputing (1998)

This paper presents parallel algorithms for computing multi-dimensional wavelet transforms on both shared memory and distributed memory machines. Traditional data partitioning methods for n-dimensional Discrete Wavelet Transforms (DWTs) call for data redistribution once a one dimensional wavelet transform is computed along each dimension. To avoid the data communication inherent in this redistribution, two new partitioning methods called CRBP (Communication Reduced Block Partitioning) and CRLP (Communication Reduced Layer Partitioning) are proposed. The efficiency of the algorithms is compared through several examples implemented on a cluster of SGI workstations. Two kinds of parallel approaches are used to compute multi-dimensional wavelet transforms on shared memory machines: homogeneous parallelism, and heterogeneous parallelism. Homogeneous parallelism uses traditional data partitioning while heterogeneous parallelism uses the CRBP approach. The effectiveness of these approaches is demonstrated through several examples implemented on an SGI Power Challenge. The paper discusses the effectiveness of each of the approaches on the two kinds of architectures.
A rejection technique for sampling from log-concave multivariate distributions
Authors: Josef Leydold
Venue: ACM Transactions on Modeling and Computer Simulation (TOMACS) (1998)

Different universal methods (also called automatic or black-box methods) have been suggested for sampling form univariate log-concave distributions. The descriptioon of a suitable universal generator for multivariate distributions in arbitrary dimensions has not been published up to now. The new algorithm is based on the method of transformed density rejection. To construct a hat function for the rejection algorithm the multivariate density is transformed by a proper transformation T into a concave function (in the case of log-concave density T(x) = log(x).) Then it is possible to construct a dominating function by taking the minimum of serveral tangent hyperplanes that are transformed back by T-1 into the original scale. The domains of different pieces of the hat function are polyhedra in the multivariate case. Although this method can be shown to work, it is too slow and complicated in higher dimensions. In this article we split the Rn into simple cones. The hat function is constructed piecewise on each of the cones by tangent hyperplanes. The resulting function is no longer continuous and the rejection constant is bounded from below but the setup and the generation remains quite fast in higher dimensions; for example, n = 8. The article describes the details of how this main idea can be used to construct algorithm TDRMV that generates random tuples from a multivariate log-concave distribution with a computable density. Although the developed algorithm is not a real black box method it is adjustable for a large class of log-concave densities.
Speeding up technology-independent timing optimization by network partitioning
Authors: Rajat Aggarwal, Rajeev Murgai, Masahiro Fujita
Venue: Proceedings of the 1997 IEEE/ACM international conference on Computer-aided design (1997)

Technology-independent timing optimization is an important problem in logic synthesis. Although many promising techniques have been proposed in the past, unfortunately they are quite slow and thus impractical for large networks. In this paper, we propose DEPART, a delay-based partitioner-cum-optimizer, which purports to solve this problem. Given a combinational logic network that is to be optimized for timing, DEPART divides it into sub-networks using timing information and a constraint on the maximum number of gates allowed in a single sub-network. These sub-networks are then dispatched, one by one, to a standard timing optimizer. The optimized sub-networks are re-glued, generating an optimized network. The challenge is how to partition the original network into sub-networks so that the final solution quality after partitioning and optimization is comparable to that from the timing optimizer. We propose a partitioning technique that is timing-driven and is simple yet effective. We compare DEPART with speed_up, a state-of-the-art timing optimization tool, and with various partitioning techniques such as min-cut based and region growing, on a suite of large industrial and ISCAS circuits. On more than half of the benchmarks, DEPART yields run-time improvements of 20 to 450 times over a normal invocation of speed_up (the overall average improvement being 8 times), without compromising the solution quality much. Min-cut and region growing partitioning schemes, not being timing-driven, perform poorly in terms of the final circuit delay.
Kruppa's Equations Derived from the Fundamental Matrix
Authors: Richard I. Hartley
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1997)

The purpose of this note is to give a specific form for Kruppa's equations in terms of the Fundamental matrix. Kruppa's equations can be written explicitly in terms of the singular value decomposition (SVD) of the fundamental matrix.
Versatile integrity and security environment (VISE) for computer systems
Authors: Charles G. Limoges, Ruth R. Nelson, John H. Heimann, David S. Becker
Venue: Proceedings of the 1994 workshop on New security paradigms (1994)

We have developed a model of security and integrity for computer systems, the Versatile Integrity and Security Environment (VISE), which describes the basic functionality of these systems and which addresses data confidentiality and correctness of processing. It has yielded significant insight into secure application-oriented systems and is applicable to both Department of Defense and commercial requirements. Based on our model, we have developed an implementation framework which provides for enforcement of flexible access controls that are easily defined and tailored to meet a variety of requirements. This paper examines the integrity problem, discusses the general ideas behind VISE, illustrates the requirements of the framework, and demonstrates how the framework meets a general need for secure, high-integrity processing systems.
A Characterization of Distance-Regular Graphs with DiameterThree
Authors: Edwin R. Van Dam, Willem H. Haemers
Venue: Journal of Algebraic Combinatorics: An International Journal (1997)

We characterize the distance-regular graphs with diameter three by giving an expression for the number of vertices at distance two from each given vertex, in terms of the spectrum of the graph.
A survey of approximately optimal solutions to some covering and packing problems
Authors: Vangelis T. Paschos
Venue: ACM Computing Surveys (CSUR) (1997)

We survey approximation algorithms for some well-known and very natural combinatorial optimization problems, the minimum set covering, the minimum vertex covering, the maximum set packing, and maximum independent set problems; we discuss their approximation performance and their complexity. For already known results, any time we have conceived simpler proofs than those already published, we give these proofs, and, for the rest, we cite the simpler published ones. Finally, we discuss how one can relate the approximability behavior (from both a positive and a negative point of view) of vertex covering to the approximability behavior of a restricted class of independent set problems.
Adaptive Wavelet Methods for Hyperbolic PDEs
Authors: Mats Holmström, Johan Waldén
Venue: Journal of Scientific Computing (1998)

We analyze how to solve hyperbolic PDEs with compactly supported orthonormal wavelets adaptively. We use thresholded wavelet expansions of signals and operators. A tree structure is used to represent the signal, and a multidimensional analogue of the fast wavelet transform is used to expand the operators. We solve the advection equation and Burgers' equation on a periodic domain.
High Linearity BiCMOS Multiplier/Transconductor Structures
Authors: Nabil I. Khachab, Abdul-Aziz Al-Saqer, Joji G. Varghese
Venue: Analog Integrated Circuits and Signal Processing (1998)

A new wide-input range BiCMOS analog multiplier is proposed based on the triode and saturation region operation of the MOS transistors. The new circuit can also be reconfigured to operate as a versatile Operational Transconductance Amplifier, OTA, with independent current bias control for N stages. The novel design involves the use of attenuators at the input stage to boost the input linear range. It also utilizes a high output impedance subtractor setup at the output stage to obtain a single-ended output. The new circuit is characterized by its large input range, its high linearity and ability to operate at low voltages as well as high frequencies. HSPICE simulation results of the circuit, using the MOSIS 2 &micro;m process parameters, resulted in an input range of &plusmn;4 V (&plusmn;5 V supply), &plusmn;1.9 V (&plusmn;3 V supply) and &plusmn;1 V (&plusmn;2 V supply), with linearity error less than 0.5%. It&rsquo;s usages in certain analog signal processing applications are also discussed.
Integrating Ada with existing systems: the ATACC experience
Authors: James Ware
Venue: Proceedings of the conference on TRI-ADA '90 (1990)

Designed around existing hardware and software, the Advanced Tactical Air Command Central (ATACC), which updates Marine Corps aviation commanders' command/control capabilities, provides insight into both management and technical challenges of integrating Ada.
Clausal Discovery
Authors: Luc De Raedt, Luc Dehaspe
Venue: Machine Learning (1997)

The clausal discovery engine claudien is presented. CLAUDIEN is an inductive logic programming engine that fits in the descriptive data mining paradigm. CLAUDIEN addresses characteristic induction from interpretations, a task which is related to existing formalisations of induction in logic. In characteristic induction from interpretations, the regularities are represented by clausal theories, and the data using Herbrand interpretations. Because CLAUDIEN uses clausal logic to represent hypotheses, the regularities induced typically involve multiple relations or predicates. CLAUDIEN also employs a novel declarative bias mechanism to define the set of clauses that may appear in a hypothesis.
Dynamic communication models in embedded system co-simulation
Authors: Ken Hines, Gaetano Borriello
Venue: Proceedings of the 34th annual Design Automation Conference (1997)

Many co-simulation techniques either suffer from poor performancewhen simulating communications intensive systems, or theyrepresent communications with a uniformly low level of detail.This paper presents a technique which allows communication tobe represented at multiple levels of detail and which gives a designerthe ability to dynamically choose the appropriate level fordifferent parts of the system. This paper also presents a tool whichuses this technique and experiments which show relative simulationspeedups.
Integrated enterprise modeling: method and tool
Authors: Kai Mertins, Roland Jochem
Venue: ACM SIGGROUP Bulletin (1997)

Success is not a static figure; it has to be constantly secured anew. The adaptability to changing competitive requirements is becoming a crucial factor of performance. The company of the future needs to be oriented towards integrated and model-based planning to allow open, flexible and changeable structures and business processes. This paper introduces a model-based method and a tool to adapt the necessary strategies and measures purposefully and continuously to the changing market requirements within the framework of corporate planning.
Dummynet: a simple approach to the evaluation of network protocols
Authors: Luigi Rizzo
Venue: ACM SIGCOMM Computer Communication Review (1997)

Network protocols are usually tested in operational networks or in simulated environments. With the former approach it is not easy to set and control the various operational parameters such as bandwidth, delays, queue sizes. Simulators are easier to control, but they are often only an approximate model of the desired setting, especially for what regards the various traffic generators (both producers and consumers) and their interaction with the protocol itself.In this paper we show how a simple, yet flexible and accurate network simulator - dummynet - can be built with minimal modifications to an existing protocol stack, allowing experiments to be run on a standalone system. dummynet works by intercepting communications of the protocol layer under test and simulating the effects of finite queues, bandwidth limitations and communication delays. It runs in a fully operational system, hence allowing the use of real traffic generators and protocol implementations, while solving the problem of simulating unusual environments. With our tool, doing experiments with network protocols is as simple as running the desired set of applications on a workstation.A FreeBSD implementation of dummynet, targeted to TCP, is available from the author. This implementation is highly portable and compatible with other BSD-derived systems, and takes less than 300 lines of kernel code.