ppxscal/embedding_network huggingface dataset:
Note: An Upper Bound for the Diameter of a Graph
Authors: Russell Merris
Venue: SIAM Journal on Discrete Mathematics (1999)

In an article [SIAM J. Discrete Math., 7 (1994), pp. 443--457], Chung, Faber, and Manteuffel established an inequality for the diameter of a graph in terms of its Laplacian eigenvalues, one that could be stated more attractively if graphs with a given property did not exist. The purpose of this note is to exhibit graphs having that given property.
Discrete Anisotropic Curve Shortening Flow
Authors: Gerhard Dziuk
Venue: SIAM Journal on Numerical Analysis (1999)

Anisotropic curve shortening flow is a geometric evolution of a curve and is equivalent to the gradient flow of anisotropic interface energy. We develop a numerical scheme for this nonlinear and degenerate problem, which is based on the fact that the evolution problem can be written formally as a linear partial differential equation on the interface itself. The scheme requires the solution of a tridiagonal complex linear system in each time step. We prove optimal error estimates in adequate norms for the semidiscrete scheme and provide numerical test computations. The scheme can also be applied to crystalline energies.
Segmentation techniques for analysis of bone by three-dimensional computed tomographic imaging
Authors: Thomas Dufresne
Venue: Technology and Health Care (1998)

Improved methods for evaluation and quantification of the three-dimensional (3D) architecture of bone are needed in order to more fully understand the role of trabecular architecture in bone strength. Computed tomography (\muCT) is capable of examining bone at resolutions below 30 \mum (isotropic), with collection of a three-dimensional data set which can then be subjected to image analysis. In this paper, we discuss automated methods for important steps in this analysis, including methods for (1) segmenting the image into bone and background; (2) defining the volume of interest for determination of structural parameters; and (3) segmenting the bone into trabecular and cortical components. Evaluation of bone structure using these techniques provides new information about the 3D architecture of bone tissue, and may be useful for evaluation of structural changes in bone caused by aging, disease, or drug treatment.
Scheduling Distributed Real-Time Tasks with Minimum Jitter
Authors: Marco Di Natale, John A. Stankovic
Venue: IEEE Transactions on Computers (2000)

The problem of scheduling real-time tasks with minimum jitter is particularly important in many control applications; nevertheless, it has rarely been studied in the scientific literature. This paper presents a unconventional scheduling approach for distributed static systems where tasks are periodic and have arbitrary deadlines, precedence, and exclusion constraints. The solution presented in this work not only creates feasible schedules, but also minimizes jitter for periodic tasks. We present a general framework consisting of an abstract architecture model and a general programming model. We show how to design a surprisingly simple and flexible scheduling method based on simulated annealing. Experimental results demonstrate the significant improvement of our algorithm over earliest deadline first and rate monotonic algorithms.
Pseudospectral vs. Finite Difference Methods for Initial Value Problems with Discontinuous Coefficient
Authors: Erding Luo, Heinz-Otto Kreiss
Venue: SIAM Journal on Scientific Computing (1998)

An initial value problem with piecewise-constant coefficients is considered. The accuracies for both finite difference methods and the pseudospectral method are analyzed, and a modification of the initial value problem is suggested. The modified problem is shown to have the same temporal period as the original problem does, and a second-order accuracy is obtained for the pseudospectral method at integral multiples of the temporal period.
Self-tuning histograms: building histograms without looking at data
Authors: Ashraf Aboulnaga, Surajit Chaudhuri
Venue: Proceedings of the 1999 ACM SIGMOD international conference on Management of data (1999)

In this paper, we introduce self-tuning histograms. Although similar in structure to traditional histograms, these histograms infer data distributions not by examining the data or a sample thereof, but by using feedback from the query execution engine about the actual selectivity of range selection operators to progressively refine the histogram. Since the cost of building and maintaining self-tuning histograms is independent of the data size, self-tuning histograms provide a remarkably inexpensive way to construct histograms for large data sets with little up-front costs. Self-tuning histograms are particularly attractive as an alternative to multi-dimensional traditional histograms that capture dependencies between attributes but are prohibitively expensive to build and maintain. In this paper, we describe the techniques for initializing and refining self-tuning histograms. Our experimental results show that self-tuning histograms provide a low-cost alternative to traditional multi-dimensional histograms with little loss of accuracy for data distributions with low to moderate skew.
On the Theory of Complex Rays
Authors: S. J. Chapman, J. M. H. Lawry, J. R. Ockendon, R. H. Tew
Venue: SIAM Review (1999)

The article surveys the application of complex-ray theory to the scalar Helmholtz equation in two dimensions.The first objective is to motivate a framework within which complex rays may be used to make predictions about wavefields in a wide variety of geometrical configurations. A crucial ingredient in this framework is the role played by Sp{} in determining the regions of existence of complex rays. The identification of the Stokes surfaces emerges as a key step in the approximation procedure, and this leads to the consideration of the many characterizations of Stokes surfaces, including the adaptation and application of recent developments in exponential asymptotics to the complex Wentzel--Kramers--Brilbuin expansion of these wavefields.Examples are given for several cases of physical importance.
Simple Algorithms for Routing on Butterfly Networks with Bounded Queues
Authors: Bruce M. Maggs, Ramesh K. Sitaraman
Venue: SIAM Journal on Computing (1999)

This paper examines several simple algorithms for routing packets on butterfly networks with bounded queues. We show that for any greedy queuing protocol, a routing problem in which each of the N inputs sends a packet to a randomly chosen output requires O(log N) steps, with high probability, provided that the queue size is a sufficiently large, but fixed, constant. We also show that for any deterministic nonpredictive queuing protocol, there exists a permutation that requires $\Omega(N/q \log N)$ time to route, where q is the maximum queue size. We present a new algorithm for routing log N packets from each input to randomly chosen outputs on a butterfly with bounded-size queues in O(log N) steps, with high probability. The algorithm is simpler than the previous algorithms of Ranade and Pippenger because it does not use ghost messages, it does not compare the ranks or destinations of packets as they pass through switches, and it cannot deadlock. Finally, using Valiant's idea of random intermediate destinations, we generalize a result of Koch's by showing that if each wire can support $q$ messages, then for any permutation, the expected number of messages that succeed in locking down paths from their origins to their destinations in back-to-back butterflies is $\Omega(N/(\log N)^{1/q})$. The analysis also applies to store-and-forward algorithms that drop packets if they attempt to enter full queues.
Network management using expert diagnostics
Authors: Wayne Fuller
Venue: International Journal of Network Management (1999)

Networks have become a key component of the corporate infrastructure. Managing the networks, which often carry a diverse set of information &lpar;e.g. voice, data, video&rpar; over a diverse set of media &lpar;e.g. wire, cable, RF&rpar; with a mixture of owned and leased transmission assets that are often geographically distributed and run a diverse set of protocols, is a major challenge. One of the most promising techniques applies expert system approaches to the management of networks. Copyright &copy; 1999 John Wiley Sons, Ltd.
Simultaneous reference allocation in code generation for dual data memory bank ASIPs
Authors: Ashok Sudarsanam, Sharad Malik
Venue: ACM Transactions on Design Automation of Electronic Systems (TODAES) (2000)

We address the problem of code generation for DSP systems on a chip. In such systems, the amount of silicon devoted of program ROM is limited, so application software must be sufficiently dense. Additionally, the software must be written so as to meet various high-performance constraints, which may include hard real-time constraints. Unfortunately, current compiler technology is unable to generate high-quality code for DSPs, whose architectures are highly irregular. Thus, designers often resort to programming application software in assembly&mdash;a time-consuming task. In this paper, we focus on providing support for architectural feature of DSPs that makes code generation difficult, namely multiple data memory banks. This feature increases memory bandwith by permitting multiple data memory accesses to occur in parallel when the referenced variables belong to different data memory banks and the registers involved conform to a strict set of conditions. We present an algorithm that attempst to maximize the benefit of this architectural feature. While previous approaches have decoupled the phases of register allocation and memory bank assignment, thereby compromising code quality, our algorithm performs these two phases simultaneously. Experimental results demonstrate that our algorithm not only generates high-quality compiled code, but also improves the quality of completely-referenced code.
Diluting ACID
Authors: Tim Kempster, Colin Stirling, Peter Thanisch
Venue: ACM SIGMOD Record (1999)

Several DBMS vendors have implemented the ANSI standard SQL isolation levels for transaction processing. This has created a gap between database practice and textbook accounts of transaction processing which simply equate isolation with serializability. We extend the notion of conflict to cover lower isolation levels and we present improved characterisations of classes of schedules achieving these levels.
Control of the Stochastic Burgers Model of Turbulence
Authors: Giuseppe Da Prato, Arnaud Debussche
Venue: SIAM Journal on Control and Optimization (1999)

We consider a control problem for a stochastic Burgers equation. This problem is motivated by a model from the control of Turbulence (see [Choi et al., J. Fluid Mech., 253 (1993), pp. 509--543]). We study a sequence of approximated Hamilton--Jacobi equations by using dynamic programming.
A Modular Analog NLMS Structure for Adaptive Filtering
Authors: Luis Niño-de-Rivera, Hector Perez-Meana, Edgar Sanchez-Sinencio
Venue: Analog Integrated Circuits and Signal Processing (1999)

This paper proposes a modular Analog Adaptive filter (AAF) algorithm, in which the coefficient adaptation is carried out by using a time varying step size analog normalized LMS (NLMS) algorithm, which is implemented as an external analog structure. The proposed time varying step size is estimated by using the first element of the crosscorrelation vector between the output error and reference signal, and the first element of the crosscorrelation vector between the output error and the adaptive filter output signal, respectively. Proposed algorithm reduces distortion when additive noise power increases or DC offsets are present, without significatively decreasing the convergence rate nor increasing the complexity of the conventional NLMS algorithms. Simulation results show that proposed algorithm improves the performance of AAF when DC offsets are present. The proposed VLSI structure for the time varying step size normalized NLMS algorithm has, potentially, a very small size and faster convergence rates than its digital counterparts. It is suitable for general purpose applications or oriented filtering solution such as echo cancellation and equalization in cellular telephony in which high performance, low power consumption, fast convergence rates and small size adaptive digital filters (ADF) are required. The convergence performance of analog adaptive filters using integrators like first order low pass filter is analyzed.
Hardware spatial forwarding for widely shared data
Authors: Marius Pirvu, Laxmi Bhuyan
Venue: Proceedings of the 14th international conference on Supercomputing (2000)

Applications with widely shared data do not perform well on cc-NUMA multiprocessors due to the hot-spots they create in the system. In this paper we address this problem by enhancing the memory controller with a forwarding mechanism capable of hiding the read latency of widely shared data, while potentially decreasing the memory and network contention. Based on the influx of requests, the memory anticipates the next read references and forwards the data in advance to the processors. To identify the set of processors the data is to be forwarded to we use a heuristic based on the spatial locality of memory blocks. To increase the forwarding effectiveness and minimize the number of messages, we incorporate simple filters combined with a feedback mechanism. We also show that further improvements are possible using a combined software-prefetching/hardware-forwarding approach. Our experimental results obtained with a detailed execution driven simulator with ILP processors show significant improvements in execution time (up to 37%).
Issues and challenges in developing embedded software for information appliances and telecommunication terminals
Authors: In Ryu
Venue: Proceedings of the ACM SIGPLAN 1999 workshop on Languages, compilers, and tools for embedded systems (1999)

Information appliances are emerging in the consumer electronics market with the convergence of disparate technologies including internet access, wireless connectivity, digital audio/video support, and platform independent middleware services. This presents a great deal of new challenges to developers in the consumer electronics industry due to extremely diverse hardware components and increased software complexity.This presentation will raise a variety of technical issues we have encountered during the development of various commercial products such as digital TVs, web video phones, wireless handsets, and CDMA terminals. We will discuss in detail about proliferation of the types of consumer devices, diversity in hardware and component software technologies, and newly emerging data storage technologies for embedded systems. We will also touch upon other essential issues for embedded systems development such as quality assurance, fault isolation, power management, and optimal system design based on functional partitioning.
The Geometry of Fractional Stable Matchings and its Applications
Authors: Chung-Piaw Teo, Jay Sethuraman
Venue: Mathematics of Operations Research (1998)

We study the classical stable marriage and stable roommates problems using a polyhedral approach. We propose a new LP formulation for the stable roommates problem, which has a feasible solution if and only if the underlying roommates problem has a stable matching. Furthermore, for certain special weight functions on the edges, we construct a 2-approximation algorithm for the optimal stable roommates problem. Our technique exploits features of the geometry of fractional solutions of this formulation. For the stable marriage problem, we show that a related geometry allows us to express any fractional solution in the stable marriage polytope as a convex combination of stable marriage solutions. This also leads to a genuinely simple proof of the integrality of the stable marriage polytope.
Exploring the boundaries of successful GSS application: supporting inter-organizational policy networks
Authors: Gert-Jan de Vreede, Hans de Bruijn
Venue: ACM SIGMIS Database (1999)

Technologies used to support group work are based on, and contain underlying assumptions regarding, how people work together. The appropriateness of such assumptions is an important factor in determining the successful employment of the technology. This paper uses an action research approach to explore the boundaries of effective GSS application by challenging the basic assumptions built into GSS. This exploration is carried out in the context of a particular arena in which groups have to interact to reach a certain goal: inter-organizational policy networks. From nine cases it appears that GSS are most effective in the orientation phase of inter-organizational policy making, while GSS should be avoided during the separation phase where winners and losers can be identified. During the package deal phase of an inter-organizational policy making process, GSS may have added value to offer, but the technology should be employed with caution. These findings are consistent with various experimental studies that found that GSS application is more successful for creativity tasks than for preference tasks and mixed motive tasks.
SQL: 1999, formerly known as SQL3
Authors: Andrew Eisenberg, Jim Melton
Venue: ACM SIGMOD Record (1999)

For several years now, you've been hearing and reading about an emerging standard that everybody has been calling SQL3. Intended as a major enhancement of the current second generation SQL standard, commonly called SQL-92 because of the year it was published, SQL3 was originally planned to be issued in about 1996&hellip;but things didn't go as planned. As you may be aware, SQL3 has been characterized as &ldquo;object-oriented SQL&rdquo; and is the foundation for several object-relational database management systems (including Oracle's ORACLE8, Informix' Universal Server, IBM's DB2 Universal Database, and Cloudscape's Cloudscape, among others). This is widely viewed as a &ldquo;good thing&rdquo;, but it has had a downside, too: it took nearly 7 years to develop, instead of the planned 3 or 4. As we shall show, SQL:1999 is much more than merely SQL-92 plus object technology. It involves additional features that we consider to fall into SQL's relational heritage, as well as a total restructuring of the standards documents themselves with an eye towards more effective standards progression in the future.
Fuzzy Relative Position Between Objects in Image Processing: A Morphological Approach
Authors: Isabelle Bloch
Venue: IEEE Transactions on Pattern Analysis and Machine Intelligence (1999)

In order to cope with the ambiguity of spatial relative position concepts, we propose a new definition of the relative position between two objects in a fuzzy set framework. This definition is based on a morphological and fuzzy pattern-matching approach, and consists of comparing an object to a fuzzy landscape representing the degree of satisfaction of a directional relationship to a reference object. It has good formal properties, it is flexible, it fits the intuition, and it can be used for structural pattern recognition under imprecision. Moreover, it also applies in 3D and for fuzzy objects issued from images.
RecPlay: a fully integrated practical record/replay system
Authors: Michiel Ronsse, Koen De Bosschere
Venue: ACM Transactions on Computer Systems (TOCS) (1999)

This article presents a practical solution for the cyclic debugging of nondeterministic parallel programs. The solution consists of a combination of record/replay with automatic on-the-fly data race detection. This combination enables us to limit the record phase to the more efficient recording of the synchronization operations, while deferring the time-consuming data race detection to the replay phase. As the record phase is highly efficient, there is no need to switch it off, hereby eliminating the possibility of Heisenbugs because tracing can be left on all the time. This article describes an implementation of the tools needed to support RecPlay.
Lower bound on latency for VLIW ASIP datapaths
Authors: Margarida F. Jacome, Gustavo de Veciana
Venue: Proceedings of the 1999 IEEE/ACM international conference on Computer-aided design (1999)

Traditional lower bound estimates on latency for dataflow graphs assume no data transfer delays. While such approaches can generate tight lower bounds for datapaths with a centralized register file, the results may be uninformative for datapaths with distributed register file structures that are characteristic of VLIW ASIPs. In this paper we propose a latency bound that accounts for such data transfer delays. The novelty of our approach lies in constructing the &ldquo;window dependency graph&rdquo; and bounds associated with the problem which capture delay penalties due to operation serialization and/or data moves among distributed register files. Through a set of benchmark examples, we show that the bound is competitive with state-of-the-art approaches. Moreover, our experiments show that the approach can aid an iterative improvement algorithm in determining good functional unit assignments &mdash; a key step in code generation for VLIW ASIPs.
Supporting collaborative field operations with personal information processing systems
Authors: Stephanie Guerlain, Jim Lee, Troy Kopischke, Tom Romanko, Peter Reutiman, Scott Nelson
Venue: Mobile Networks and Applications (1999)

This paper describes a two-year research project to develop a personal information processing system (PIPS) solution for the roving industrial field operator. Our PIPS system comprises (1) an RF network to deliver wireless digital information, (2) a wearable computer for delivering web-based information (the hardware is a two-piece system composed of a belt-worn NetPC attached via a curly cable to a handheld unit with a mouse/display device combination), and (3) software applications that provide added value in the field. Unique challenges in designing such a system for this environment include providing: (1) good RF coverage in an environment with many metal structures; (2) an intrinsically safe, lightweight, low-cost hardware system; and (3) software that is compatible with the wearable system and supports collaboration in the field.
A Unified Theory of Uncalibrated Stereo for Both Perspective and Affine Cameras
Authors: Zhengyou Zhang, Gang Xu
Venue: Journal of Mathematical Imaging and Vision (1998)

This paper addresses the recovery of structure and motion from uncalibrated images of a scene under full perspective or under affine projection. Particular emphasis is placed on the configuration of two views, while the extension to $N$ views is given in Appendix. A unified expression of the fundamental matrix is derived which is valid for any projection model without lens distortion (including full perspective and affine camera). Affine reconstruction is considered as a special projective reconstruction. The theory is elaborated in a way such that everyone having knowledge of linear algebra can understand the discussion without difficulty. A new technique for affine reconstruction is developed, which consists in first estimating the affine epipolar geometry and then performing a triangulation for each point match with respect to an implicit common affine basis.