ppxscal/embedding_network huggingface dataset:
Scale-Based Description and Recognition of Planar Curves and Two-Dimensional Shapes
Authors: Farzin Mokhtarian, Alan K. Mackworth
Venue:  (1984)

The problem of finding a description for planar curves and two-dimensional shapes at varying levels of detail and matching two such descriptions is posed and solved in this paper. A number of necessary criteria are imposed on any candidate solution method. Path-based Gaussian smoothing techniques are applied to the curve to find zeroes of curvature at varying levels of detail. The result is the `generalized scale space'' image of a planar curve which is invariant under rotation, uniform scaling and translation of the curve. These properties make the scale space image suitable for matching. The matching algorithm is a modification of the uniform cost algorithm and finds the lowest cost match of contours in the scale space images. It is argued that this is preferable to matching in a stable scale of the curve because no such scale may exist for a given curve. This technique is applied to register a Landsat aerial image of the Strait of Georgia, B.C. (manually corrected for skew) to a map containing the shorelines of an overlapping area.
Adjoining to Wythoff''s Game its P-positions as Moves
Authors: A. S. Fraenkel, M. Ozery
Venue:  (1996)

A rewarding method for generating a new game G>sub<i+1>/sub< from a known game G>sub/sub< is to adjoin an appropriate subset of the P-positions (2nd player winning positions) of G>sub/sub< to G>sub<i+1>/sub< as moves. We illustrate this statement by adjoining to the generalized Wythoff Game three subsets of its P-positions as moves, resulting in three different classes of games. We analyze these classes, characterizing the P-positions of some and exhibiting equivalences between others.
Magnetohydroynamic Free Convection from a Disk Rotating in a Vertical Plane
Authors: William I. Thacker, Layne T. Watson, Kishore S. Kumar
Venue:  (1988)

The non-axisymmetric motion (produced by a buoyancy induced cross flow) of a fluid in contact with a rotating disk and in the presence of a magnetic field normal to the disk is studied. Using modern quasi- Newton techniques, B-splines, and a Galerkin approximation to the fluid motion equations, numerical solutions are obtained for a wide range of magnetic field strengths and Prandtl numbers (ratio of kinematic viscosity to thermal conductivity). Results are presented both in tabular and graphical form in terms of two non-dimensional parameters. There is excellent agreement with previous work.
Synthesizing State-Based Object Systems from LSC Specifications
Authors: D. Harel, H. Kugler
Venue:  (1999)

Live sequence charts (LSCs) have been defined recently as an extension of message sequence charts (MSCs; or their UML variant, sequence diagrams) for rich inter-object specification. One of the main additions is the notion of universal charts and hot, mandatory behavior, which, among other things, enables one to specify forbidden scenarios. LSCs are thus essentially as expressive as statecharts. This paper deals with synthesis, which is the problem of deciding, given an LSC specification, if there exists a satisfying object system and, if so, to synthesize one automatically. The synthesis problem is crucial in the development of complex systems, since sequence diagrams serve as the manifestation of use cases - whether used formally or informally - and if synthesizable they could lead directly to implementation. Synthesis is considerably harder for LSCs than for MSCs, and we tackle it by defining consistency, showing that an entire LSC specification is consistent iff it is satisfiable by a state-based object system, and then synthesizing a satisfying system as a collection of finite state machines or statecharts.
Availability and Latency of World Wide Web Information Servers
Authors: Charles L. Viles, James C. French
Venue:  (2001)

During a 90 day period in 1994, we measured the availability and connection latency of HTTP (hypertext transfer protocol) information servers. These measurements were made from a site in the Eastern United States. The list of servers included 189 servers from Europe and 324 servers from North America. Our measurements indicate that on average, 5.0% of North American servers and 5.4% of European servers were unavailable from the measurement site on any given day. As seen from the measurement site, the day-to-day variation in availability was much greater for the European servers than for the North American servers. The measurements also show a wide variation in availability for individual information servers. For example, more than 80% of all North American servers were available at least 95% of the time, but 5% of the servers were available less than 80% of the time. The pattern of unavailability suggests a strong correlation between unavailability and geographic location. Median connection latency from the measurement site was in the 0.2 - 0.5s range to other North American sites and the 0.4 - 2.5s to European sites, depending upon the day of the week. Latencies were much more variable to Europe than to North America. The magnitude of the latencies suggest the addition of an MGET method to HTTP to help alleviate large TCP set-up times associated with the retrieval of web pages with embedded images. The data show that 97% and 99% of all successful connections from the measurement site to Europe and North America respectively were made within the first 10 s. This suggests the establishment of client-side time-out intervals much shorter than those used for normal TCP connection establishment.
On the Power of a Posteriori Error Estimation for Numerical Integration and Function Approximation
Authors: Feng Gao
Venue:  (1990)

We show that using a type of divided-difference test as an a posteriori error criterion, the solutions of a class of simple adaptive algorithms for numerical integration and function approximation such as a piecewise Newton-Cotes rule or a piecewise Lagrange interpolation, are guaranteed to have an approximation-theoretic property of near-optimality. Namely, upon successful termination of the algorithm the solution is guaranteed to be close to the solution given by the spline interpolation method on the same mesh to within any prescribed tolerance.
Open courseware and open source software
Authors: Stefan Baldi, Hauke Heier, Anett Mehler-Bicher
Venue: Communications of the ACM (2003)

Learning from experience?
OPTICAL JUKEBOX RETRIEVAL PERFORMANCE IN ELECTRONIC LIBRARIES UTILIZING CYCLIC SCHEDULING
Authors: David E. Levy, Patrick E. Mantey
Venue:  (1992)

The optical jukebox emerges as the economic choice for storing huge quantities of data objects in today''s electronic libraries. Sequential access to collections in an electronic library with a very large number of holdings significantly limits library response when requests are frequent, as found in large-scale library systems. Therefore, we consider an alternative scheduling method which takes advantage of specific user and application characteristics found in a library environment. In this paper, we address the performance benefits of cyclic scheduling of user requests in electronic libraries where retrievals are the primary tasks. An approximate model of the retrieval performance is developed in terms of average waiting times for retrieval of objects from an optical jukebox using a cyclic service strategy. This model considers variability in service and its evaluation involves an iterative approach. In addition, the goal of the approximation is motivated by providing a user-interface prompt which indicates the expected waiting times for requested documents. (not available electronically).
SCHEDULING REAL-TIME DISK TRANSFERS FOR CONTINUOUS MEDIA APPLICATIONS
Authors: Darrell D.E. Long, Madhukar N. Thakur
Venue:  (1993)

We study how continuous media data can be stored and accessed in the Swift distributed I/O architecture. We provide a scheme for scheduling real-time data transfers that satisfies the strict requirements of continuous media applications. Our scheme allows large data objects to be stored and retrieved concurrently from multiple disks so as to satisfy the high data rate requirements which are typical of real-time video and audio data. To do this, data transfer requests are split into smaller requests which are then handled by the various components of Swift. We study on-line algorithms that respond to a data request by promising to either satisfy or reject it. Each response must be made before the next request is seen by the algorithm. We discuss two different performance measures to evaluate such algorithms and show that no on-line algorithm can optimize these criteria to less than a constant fraction of the optimal. Finally, we propose an algorithm for handling such requests on-line and the related data structures.
A Multigrid Solver for the Steady State Navier-Stokes Equations Using The Pressure-Poisson Formulation
Authors: David Sidilkover, Uri M. Ascher
Venue:  (1994)

This paper presents an efficient multigrid solver for steady-state Navier-Stokes equations in 2D on non-staggered grids. The pressure Poisson equation formulation is used, together with a finite volume discretization. A discretization of the boundary conditions for pressure and velocities is presented. An efficient multigrid algorithm for solving the resulting discrete equations is then developed. The issue of the numerical treatment of advection is also addressed: a family of stable and accurate difference schemes for the advection-dominated flow are presented. This family includes also second order accurate schemes.
Extensible File Systems (ELFS): An Object-Oriented Approach to High Performance File I/O
Authors: John F. Karpovich, Andrew S. Grimshaw, James C. French
Venue:  (1994)

As CPU performance has rapidly improved, increased pressure has been placed on the performance of accessing external data in order to keep up with demand. Increasingly often the I/O subsystem and related software is unable to meet this demand and valuable CPU resources are left underutilized while users are forced to wait longer than necessary for results. This problem is especially acute for many scientific applications which use large data sets and require high performance. This paper presents our experiences with working to alleviate an I/O bottleneck in radio astronomy applications at the National Radio Astronomy Observatory (NRAO). We first present our model, the ExtensibLe File Systems model (ELFS), for improving both the performance of data access and the usability of access software. We then present the current situation at NRAO, our solution, performance results and our plans for future work.
On the Construction of Pseudo-Random Permutations: Luby-Rackoff Revisited
Authors: M. Naor, O. Reingold
Venue:  (1996)

Luby and Rackoff showed a method for constructing a pseudo-random permutation from a pseudo-random function. The method is based on composing four (or three for weakened security) so called Feistel permutations each of which requires the evaluation of a pseudo-random function. We reduce somewhat the complexity of the construction and simplify its proof of security by showing that two Feistel permutations are sufficient together with initial and final pair-wise independent permutations. The revised construction and proof provide a framework in which similar constructions may be brought up and their security can be easily proved. We demonstrate this by presenting some additional adjustments of the construction that achieve the following: Reduce the success probability of the adversary. Provide a construction of pseudo-random permutations with large input size using pseudo-random functions with small input size. Provide a construction of a pseudo-random permutation using a single pseudo-random function.
Trajectory Generation Implemented as a Non-linearFilter
Authors: Lloyd John E.
Venue:  (1998)

A primary purpose of robotic trajectory generation is to produce a timed path which is sufficiently well behaved that it can be tracked by a manipulator. However, the creation of good paths becomes somewhat problematic in situations where a manipulator is required to follow a target whose position is varying erratically (for instance, if the target is specified using a position sensor held in an operator''s hand). This paper presents a simple solution for such situations, in which the ``trajectory generator'''' is implemented as a non-linear filter which tries to bring its output (manipulator setpoints) to the input (target position) as quickly as possible, subject to constraints on velocity and acceleration. The solution to this problem in one dimension is quite easy. For multiple dimensions, the problem can be handled by applying one-dimensional solutions to a pair of appropriately chosen coordinate axes. An interesting feature of the approach is that it can handle spatial rotations as well as vector quantities.
Comparative Evaluation of the Multi-Class PNN and ART2 Neural Networks for Classification of Infrared Ship Images: A Preliminary Study
Authors: Anthony Zaknich, Chris deSilva
Venue:  (1991)

Abstract unavailable.
Validation of Expert System Performance
Authors: Robert M. O''Keefe, Osman Balci, Eric P. Smith
Venue:  (1986)

Most definitions of an expert system include some reference to the ability of the system to perform at a level close to human expert performance. Yet the validation of expert systems, that is, the testing of systems so as to ascertain that they achieve an acceptable level of performance, has (with a few exceptions) been ad-hoc, informal, and in some cases of dubious value. This paper attempts to establish validation as an important concern in expert systems research and development. The problems in validating an expert system are discussed, and a number of methods for validating expert systems, both qualitative and quantitative, are presented.
The Complexity of Regular Expressions with Goto and Boolean Variables
Authors: Karl Abrahamson
Venue:  (1982)

Regular expressions can be extended by adding gotos and Boolean variables. Although such extensions do not increase the class of expressible languages, they do permit shorter expressions for some languages. The output space complexity of eliminating Boolean variables is shown to be double exponential. The complexity of eliminating a single goto from a regular expression is shown to be \( \Omega (n \log n) \), a surprising result considering that $n$ gotos can be eliminated in single exponential space.
Evaluation of Active Disks for Large Decision Support Databases
Authors: Mustafa Uysal, Anurag Acharya, Joel Saltz
Venue:  (1999)

Growth and usage trends for large decision support databases indicate that there is a need for architectures that scale the processing power as the dataset grows. To meet this need, several researchers have recently proposed Active Disk architectures which integrate substantial processing power and memory into disk units. In this paper, we evaluate Active Disks for decision support databases. First, we compare the performance of Active Disks with that of existing scalable server architectures: SMP-based conventional disk farms and commodity clusters of PCs. Second, we evaluate the impact of several design choices on the performance of Active Disks. We focus on the performance impact of interconnect bandwidth, amount of disk memory, disk-to-disk communication architecture and the host processor speed on decision support workloads. Our results show that for identical disks, number of processors and I/O interconnect, Active Disks provide better price/performance than both SMP-based conventional disk farms and commodity clusters. Experiments evaluating the impact of design alternatives in Active Disk architectures indicate that: (1) for configurations up to 64 disks, a dual fibre channel arbitrated loop interconnect is sufficient even for the most communication-intensive decision support tasks; (2) most decision support tasks do not require a large amount of memory; (3) direct disk-to-disk communication is necessary for achieving good performance on tasks that repartition all (or a large fraction of) their dataset; and (4) the host processor is rarely a bottleneck for configurations up to 128 disks.
Alternate distribution strategies for digital music
Authors: G. Prem Premkumar
Venue: Communications of the ACM (2003)

Digitization of music has created opportunities to reengineer the supply chain and improve its efficiency.<br><br>But how will it play out?
Sorting by Short Block-Moves
Authors: Heath Lenwood S., Vergara John Paul C.
Venue:  (1998)

Sorting permutations by operations such as reversals and block-moves has received much interest because of its applications in computational biology, particularly in the study of genome rearrangements. A short block-move is an operation on a permutation that moves an element at most two positions away from its original position. This paper investigates the problem of finding a minimum-length sorting sequence of short block-moves for a given permutation. A 4/3-approximation algorithm for this problem is presented. Exact polynomial-time algorithms are presented for woven bitonic permutations and woven double-strip permutations. A linear-time maximum matching algorithm for a special class of grid graphs is also discovered that improves the time complexity of one of these exact algorithms.
Smart Integration: A Test Case Study
Authors: M. J. Zemerly, E. Papaefstathiou, T. J. Atherton, Darren J. Kerbyson, Graham R. Nudd
Venue:  (1993)

This study is concerned with characterisation of a parallel algorithm, namely partial 1D FFT on a parallel system (2 x T800). Analytical expressions for the "execution time" for a single processor and 2 processors are discussed and used to obtain a performance measure (execution time) for the application at hand.
Data mining for human resource information systems
Authors: Lori K. Long, Marvin D. Troutt
Venue: Data mining: opportunities and challenges (2003)

This chapter focuses on the potential contributions that Data Mining (DM) could make within the Human Resource (HR) function in organizations. We first provide a basic introduction to DM techniques and processes and a survey of the literature on the steps involved in successfully mining this information. We also discuss the importance of data warehousing and datamart considerations. An examination of the contrast between DM and more routine statistical studies is given, and the value of HR information to support a firm's competitive position and organizational decision-making is considered. Examples of potential applications are outlined in terms of data that is ordinarily captured in HR information systems.
Time-Space Tradeoffs for Branching Programs Contrasted With Those for Straight-Line Programs
Authors: Karl Abrahamson
Venue:  (1987)

This paper establishes time-space tradeoffs for some algebraic problems in the branching program model, including convolution of vectors, matrix multiplication, matrix inversion, computing the product of three matrices and computing $PAQ$ where $P$ and $Q$ are permutation matrices. While some of the results agree well with known results for straight- line programs, one of them (for matrix multiplication) surprisingly is stronger, and one (for computing $PAQ$) is necessarily weaker. Some of the tradeoffs are proved for expected time and space, where all inputs are equally likely.
A CLASS OF SYNCHRONIZATION OPERATIONS THAT PERMIT EFFICIENT RACE DETECTION
Authors: David P. Helmbold, Charles E. McDowell
Venue:  (1993)

We present an efficient algorithm for ``precisely'''' determining the possible alternate orderings of events from a program trace for a class of synchronization operations. The class includes, post and wait without clear, a restricted form of semaphores, and message passing where the sender names the receiver. The ordering information is precise in that a race detection system could be built using the ordering information such that if the program does not contain any data races for a given input, no races will be reported, and if the the program does contain data races, at least one of those races will be reported.
Time Dependent Rate-Based Modeling for Trace Data
Authors: Anup Mathur, Marc Abrams
Venue:  (1995)

This paper introduces a novel technique to construct an empirical model fitting time-varying (transient) trace data. The trace is a categorical or numerical time-series. The modeling technique described in this paper first builds a Mass Evolution Graph (MEG) from the trace data. Linear regression is then used to construct a time-dependent probability mass function (pmf) for each state in the trace data.
The Bit Complexity of Randomized Leader Election on a Ring
Authors: Karl Abrahamson, Andrew Adler, Rachel Gelbart, Lisa Higham, David G. Kirkpatrick
Venue:  (1986)

The inherent bit complexity of leader election on asynchronous unidirectional rings of processors is examined under various assumptions about global knowledge of the ring. If processors have unique identities with a maximum of $m$ bits, then the expected number of communication bits sufficient to elect a leader with probability 1, on a ring of (unknown) size $n$ is $O(nm)$. If the ring size is known to within a multiple of 2, then the expected number of communication bits sufficient to elect a leader with probability 1 is $O(n \log n)$. These upper bounds are complemented by lower bounds on the communication complexity of a related problem called solitude verification that reduces to leader election in $O(n)$ bits. If processors have unique identities chosen from a sufficiently large universe of size $s$, then the average, over all choices of identities, of the communication complexity of verifying solitude is $\Omega (n \log s)$ bits. When the ring size is known only approximately, then $\Omega (n \log n)$ bits are required for solitude verification. The lower bounds address the complexity of certifying solitude. This is modelled by tbe best case behaviour of non-deterministic solitude verification algorithms.
IUHM: a hypermedia-based model for integrating open services, data and metadata
Authors: Marc Nanard, Jocelyne Nanard, Peter King
Venue: Proceedings of the fourteenth ACM conference on Hypertext and hypermedia (2003)

This paper discusses a new hypermedia-based model known as IUHM (Information Unit Hypermedia Model). IUHM emerged as a result of the development of the OPALES system, a collaborative environment for exploring and indexing video archives in a digital library. A basic design requirement of OPALES is that it must permit and support the integration of new services throughout its life cycle. Thus, IUHM depends heavily upon the notions of extensibility and openness.Support for openness, extensibility and late binding of services is provided in the IUHM model by a single reflexive mechanism. This uniform mechanism is used for describing all relationships between arbitrary system entities, including services, data and metadata. The mechanism in question consists of a generic, computable hypertext structure with typed links, known as the Information Unit (IU), and is the minimal structural scheme to which all encapsulated entities comply.We describe and justify the design of the Information Unit, as well as the semantics of its four link types, namely role, type, owner, relative. We further describe the minimal kernel of the runtime layer responsible for the dynamic behaviour specified by the IUHM compliant hypertext network. We discuss the mechanisms involved in the dynamic binding of services and service composition. We illustrate these notions by real-world examples of the integration of metadata services within the OPALES system.