ppxscal/embedding_network huggingface dataset:
Dynamics of Lattice Kinks
Authors: Kevrekidis P.G., Weinstein M.I.
Venue:  (1999)

We consider a class of Hamiltonian nonlinear wave equations governing a field defined on a spatially discrete one dimensional lattice, with discreteness parameter, $d=h^{-1}$, where $h<0$ is the lattice spacing. The specific cases we consider in detail are the discrete sine-Gordon (SG) and discrete $\phi^4$ models. For finite $d$ and in the continuum limit ($d\to\infty$) these equations have static kink-like (heteroclinic) states which are stable. In contrast to the continuum case, due to the breaking of Lorentz invariance, discrete kinks cannot be ``Lorentz boosted" to obtain traveling discrete kinks. Peyrard and Kruskal pioneered the study of how a kink, initially propagating in the lattice dynamically adjusts in the absence of an available family of traveling kinks. We study in detail the final stages of the discrete kink''s evolution during which it is pinned to a specified lattice site (equilibrium position in the Peierls-Nabarro barrier). We find: (i) for $d$ sufficiently large (sufficiently small lattice spacing), the state of the system approaches an asymptotically stable ground state static kink (centered between lattice sites). (ii) for $d$ sufficiently small $d>d_*$ the static kink bifurcates to one or more time periodic states. For discrete SG and discrete $\phi^4$ we have: wobbling kinks which have the same spatial symmetry as the static kink as well as ``g-wobblers'''' and ``e-wobblers'''', which have different spatial symmetry. The large time limit of solutions with initial data near a kink is marked by damped oscillation about one of these two types of asymptotic states. In case (i) we compute the characteristics of the damped oscillation (frequency and $d$- dependent rate of decay). In case (ii) we prove the existence of, and give analytical and numerical evidence for the asymptotic stability of wobbling solutions. The mechanism for decay is the radiation of excess energy, stored in {\it internal modes}, away from the kink core to infinity. This process is studied in detail using general techniques of scattering theory and normal forms. In particular, we derive a {\it dispersive normal form}, from which one can anticipate the character of the dynamics. The methods we use are very general and are appropriate for the study of dynamical systems which may be viewed as a system of discrete oscillators ({\it e.g.} kink together with its {\it internal modes}) coupled to a field ({\it e.g.} dispersive radiation or phonons). The approach is based on and extends an approach of one of the authors (MIW) and A. Soffer in previous work. Changes in the character of the dynamics, as $d$ varies, are manifested in topological changes in the phase portrait of the normal form. These changes are due to changes in the types of resonances which occur among the discrete internal modes and the continuum radiation modes, as $d$ varies. Though derived from a time-reversible dynamical system, this normal form
A controlled experiment on inheritance depth as a cost factor for code maintenance
Authors: Lutz Prechelt, Barbara Unger, Michael Philippsen, Walter Tichy
Venue: Journal of Systems and Software (2003)

In two controlled experiments we compare the performance on code maintenance tasks for three equivalent programs with 0, 3, and 5 levels of inheritance. For the given tasks, which focus on understanding effort more than change effort, programs with less inheritance were faster to maintain. Daly et al. previously reported similar experiments on the same question with quite different results. They found that the 5-level program tended to be harder to maintain than the 0-level program, while the 3-level program was significantly easier to maintain than the 0-level program. We describe the design and setup of our experiment, the differences to the previous ones, and the results obtained. Ours and the previous experiments are different in several ways: We used a longer and more complex program, made an inheritance diagram available to the subjects, and added a second kind of maintenance task.When taken together, the previous results plus ours suggest that there is no such thing as usefulness or harmfulness of a certain inheritance depth as such. Code maintenance effort is hardly correlated with inheritance depth, but rather depends on other factors (partly related to inheritance depth). Using statistical modeling, we identify the number of relevant methods to be one such factor. We use it to build an explanation model of average code maintenance effort that is much more powerful than a model relying on inheritance depth.
Making gnutella-like P2P systems scalable
Authors: Yatin Chawathe, Sylvia Ratnasamy, Lee Breslau, Nick Lanham, Scott Shenker
Venue: Proceedings of the 2003 conference on Applications, technologies, architectures, and protocols for computer communications (2003)

Napster pioneered the idea of peer-to-peer file sharing, and supported it with a centralized file search facility. Subsequent P2P systems like Gnutella adopted decentralized search algorithms. However, Gnutella's notoriously poor scaling led some to propose distributed hash table solutions to the wide-area file search problem. Contrary to that trend, we advocate retaining Gnutella's simplicity while proposing new mechanisms that greatly improve its scalability. Building upon prior research [1, 12, 22], we propose several modifications to Gnutella's design that dynamically adapt the overlay topology and the search algorithms in order to accommodate the natural heterogeneity present in most peer-to-peer systems. We test our design through simulations and the results show three to five orders of magnitude improvement in total system capacity. We also report on a prototype implementation and its deployment on a testbed.
On duality theorems for a nondifferentiable minimax fractional programming
Authors: H. C. Lai, J. C. Lee
Venue: Journal of Computational and Applied Mathematics (2002)

The optimality conditions of [Lai et al. (J. Math. Anal. Appl. 230 (1999) 311)] can be used to construct two kinds of parameter-free dual models of nondifferentiable minimax fractional programming problems which involve pseudo-/quasi-convex functions. In this paper, the weak duality, strong duality, and strict converse duality theorems are established for the two dual models.
Evolvable Real-Time C3 Systems-II: Real-Time Infrastructure Requirements
Authors: B. Thuraisingham, A. Kanevsky, P. Krupp, A. Schafer, M. Gates, T. Wheeler, E. Bensley, R. Sigel, M. Squadrito
Venue: Proceedings of the 2nd IEEE International Conference on Engineering of Complex Computer Systems (1996)

MITRE's Evolvable Real-Time Comma& Control, and Communications (C3) project funded under the Air Force Mission Oriented Investigation and Experimentation (MOIE) program attempts to develop an approach that would enable current real-time systems to evolve into the systems of the future. The project has chosen Airborne Warning and Control System (AWACS) as an example to test the concepts and architectures to be developed In this paper we discuss the requirements for the infrastructure for next generation complex real-time command and control systems. This discussion also includes an overview of the infrastructure requirements for each of the three architectures that we have considered [BENS95]. Experimentation (MOIE) program attempts to develop an approach that would enable current real-time systems to evolve into the systems of the future. The project has chosen Airborne Warning and Control System (AWACS) as an example to test the concepts and architectures to be developed In this paper we discuss the requirements for the infrastructure for next generation complex real-time command and control systems. This discussion also includes an overview of the infrastructure requirements for each of the three architectures that we have considered [BENS95].
New Products
Venue: IEEE Pervasive Computing (2003)

It's no surprise that companies are integrating PDAs and cellular telephones; each deviceoffers functions that complement the other and many people carry and use both. This integration, although desirable, pits the small, lightweight phone's appeal against the desirability of a PDA with a large screen and qwerty keyboard. Today's integrated devices address this tension much better than earlier devices such as the Qualcomm (now Kyocera) pdQ 1900 Smartphone, which was 9.6 x 2.6 x 1.4 in. and weighed 9.8 oz. when it was introduced in 1999. In this month's column, we review four of the newest devices. Please continue to send us your comments about new and exciting products our readersmight be interested in. Our email address is pvcproducts@computer.org. Keith Farkas and Guerney Hunt 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
The Effectiveness of Loop Unrolling for Modulo Scheduling in Clustered VLIW Architectures
Authors: Jesús Sánchez, Antonio González
Venue: Proceedings of the Proceedings of the 2000 International Conference on Parallel Processing (2000)

Clustered organizations are becoming a common trend in the design of VLIW architectures. In this work, we propose a novel modulo scheduling approach for such architectures. The proposed technique performs the cluster assignment and the instruction scheduling in a single pass, which is shown to be more effective than doing first the assignment and later the scheduling. We also show that loop unrolling significantly enhances the performance of the proposed scheduler, especially when the communication channel among clusters is the main performance bottleneck. By selectively unrolling some loops, we can obtain the best performance with the minimum increase in code size. Performance evaluation for the SPECfp95 shows that the clustered architecture achieves about the same IPC (Instructions Per Cycle) as a unified architecture with the same resources. Moreover, when the cycle time is taken into account, a 4-cluster configuration is 3.6 times faster than the unified architecture.
Budget constrained location problem with opening and closing of facilities
Authors: Qian Wang, Rajan Batta, Joyendu Bhadury, Christopher M. Rump
Venue: Computers and Operations Research (2003)

In this paper, we study a budget constrained location problem in which we simultaneously consider opening some new facilities and closing some existing facilities. Motivations for this problem stem from applications where, due to a change in the distribution of customer demand, the existing facility system no longer provides adequate service. The objective is to minimize the total weighted travel distance for customers subject to a constraint on the budget for opening and/or closing facilities and a constraint on the total number of open facilities desired. For this problem, we develop a mathematical programming model and examine its theoretical properties. We then develop three heuristic algorithms (greedy interchange, tabu search and Lagrangian relaxation approximation) for this NP-hard problem. Computational testing of these algorithms includes an analysis of the sensitivity of the solution to the budget and the desired number of facilities. The intended application in this testing is that of locating/relocating bank branches in a large-size town such as in our data set from Amherst, New York. We also discuss the situation where operating costs are part of the objective function.
Constraint Satifaction Using Constraint Logic Programming
Authors: Pascal Van Hentenryck, Helmut Simonis, Mehmet Dincbas
Venue:  (1991)

Constraint logic programming is a new class of declarative programming languages whose primitive operations are based on constraints (e.g. constraint solving and constraint entailment). CLP languages naturally combine constraint propagation with nondeterministic choices. As a consequence, they are particularly appropriate for solving a variety of combinatorial search problems (using the global search paradigm) with a short development time and an efficiency comparable to procedural tools (using the same approach). In this paper, we describe how the CLP language {\em cc(FD)}, a successor of CHIP using consistency techniques over finite domains, can be used to solve two practical applications: test-pattern generation and car-sequencing. For both applications, we present the $cc(FD)$ program, describe how constraint solving is performed, report experimental results, and compare the approach with existing tools.
Final Cut Pro 3: The Complete Reference
Authors: Richard H. Schrand, Jackson West
Venue:  (2002)

:Get more out of Final Cut Pro 3 -- the most powerful audio/video-editing tool on the market -- with this one-stop reference and tutorial. Written by a broadcast industry expert and award-winning producer, this comprehensive resource provides you with a unique hands-on approach to improving and expanding your editing and production skills. Information-packed and logically organized, this guide teaches video projects step-by-step through the entire process -- from pre- to post-production -- and offers you professional insider tips along the way. Learn to generate special effects, manage multiple projects, use tools to merge footage sequences -- and more. Now you can bring your vision to life on screen!
Plane graphs with straight edges whose bounded faces are acute triangles
Authors: H. Maehara
Venue: Journal of Combinatorial Theory Series B (2003)

Let Tn denote a graph obtained as a triangulation of an n-gon in the plane. A cycle of Tn is called an enclosing cycle if at least one vertex lies inside the cycle. It is proved that a Tn admits a straight-line embedding in the plane whose bounded faces are all acute triangles if and only if Tn has no enclosing cycle of length ≤4. Those Tn that admit straight-line embeddings in the plane without obtuse triangle are also characterized.
High-level Architectural Simulation of the Torus Routing Chip
Authors: Lasse Natvig
Venue: Proceedings of the 1997 IEEE International Verilog HDL Conference (IVC '97) (1997)

This paper presents a simulation model of the Torus Routing Chip (TRC) written in Verilog. The model represents the functional behaviour of the routing chip down to the flit (byte) level. The TRCs are self-timed and intercon-nected in a 4 by 4 torus (mesh with wrap-around) having unidirectional channels along the x and y-dimension. To avoid deadlock situations, the TRC implements two virtual channels on every physical channel. The model is presented in a top down manner with emphasis on the modelling of the packet routing algorithm, asynchronous channels, control-led access to shared resources and the increased complexity caused by virtual channels. The testing of the model as well as experience from using Verilog to develop a high-level architectural simulation is discussed.
On the Effectiveness of Dynamic Page Placement
Authors: A M Holliday
Venue:  (1989)

An important issue in NonUniform memory Access, NUMA, multiprocessors is the extent to which dynamic placement of pages can improve performance. We argue that empirical results concerning reference patterns imply that much of the proper page placement can be done initially (and statically). Consequently, intelligent intelligent initial placement causes a significant limit on the additional improvement due to dynamic placement. We quantify this limitation in the case of NUMA machines with two levels of memory access times such as the BBN Butterfly GP1000. This result implies that useful comparisons of dynamic placement policies have to assume intelligent initial placement policies.
Performance and Reliability Analysis Using Directed Acyclic Graphs
Authors: A R Sahner, S K Trivedi
Venue:  (1985)

A graph-based modeling technique has been developed for the stochastic analysis of systems containing concurrency. The basis of the technique is the use of directed acyclic graphs. These graphs represent event-precedence networks where activities may occur serially, probabilistically, or concurrently. When a set of activities occurs concurrently, the condition for the set of activities to complete is that a specified number of the activities must complete. This includes the special cases that one or all of the activities must complete. The cumulative distribution function associated with an activity is assumed to have exponential polynomial form. Further generality is obtained by allowing these distributions to have a mass at the origin and/or at infinity. The distribution function for the time taken to complete the entire graph is computed symbolically in the time parameter $t$. The technique allows two or more graphs to be combined hierarchically. Applications of the technique to the evaluation of concurrent program execution time and to the reliability analysis of fault-tolerant systems are discussed.
Generalizations of suffix arrays to multi-dimensional matrices
Authors: Dong Kyue Kim, Yoo Ah Kim, Kunsoo Park
Venue: Theoretical Computer Science (2003)

We propose multi-dimensional index data structures that generalize suffix arrays to square matrices and cubic matrices. Giancarlo proposed a two-dimensional index data structure, the Lsuffix tree, that generalizes suffix trees to square matrices. However, the construction algorithm for Lsuffix trees maintains complicated data structures and uses a large amount of space. We present simple construction algorithms for multi-dimensional suffix arrays by applying a new partitioning technique to lexicographic sorting. Our contributions are the first efficient algorithms for constructing two-dimensional and three-dimensional suffix arrays directly.
An Integrated Post-locking, Multi-Versioning, and Transformation Scheme for Consistency Maintenance in Real-Time Group Editors
Authors: Liyin Xue, Kang Zhang, Chengzheng Sun
Venue: Proceedings of the Fifth International Symposium on Autonomous Decentralized Systems (2001)

Intention preservation is an important aspect of consistency maintenance in distributed group editors. In this paper, we first introduce a classification framework for various kinds of intentions, then propose an integrated post-locking, multi-versioning, and transformation scheme (LOVOT) for intention preservation. With this scheme, individual users' compatible intentions are preserved by operational transformation, individuals' conflicting intentions are preserved by multi-versioning, and the preservation of a syntactically and semantically consistent group intention is facilitated by post-locking. An algorithm for preserving individual users' intentions is discussed in details. The integrated scheme is fully distributed, highly responsive, non-blocking, and capable of avoiding locking overhead.
Constructing automated protocol testing oracles to accommodate specification nondeterminism
Authors: J. J. Li, Hong Liu, R. E. Seviora
Venue: Proceedings of the 6th International Conference on Computer Communications and Networks (1997)

The large number of test inputs and outputs usually involved in testing of protocols makes automated output checking necessary. An automated oracle in the test environment achieves this automation. It is imperative that the oracle should be tolerant of nondeterminism in the specifications. This paper presents an and-state method to accommodate specification nondeterminism in automated protocol resting oracles. The and-state method generates concurrent system states when encountering nondeterminism. The and-state method reduces the computational cost of an oracle by avoiding running n concurrent copies of the system to generate all n possible behaviors caused by nondeterminism. We illustrate the and-state method using example specifications given in the Specification and Description Language (SDL). We applied this method to an automated oracle of a small protocol in a network system consisting of 60 nodes. The experimental results show that this oracle facilitates random testing of the protocol.
Teach Yourself Access 2002, 2 edition
Authors: Moira Stephen
Venue:  (2003)

:Time is precious, especially when people are learning software on the job! In Teach Yourself Access 2002, the author leads readers through one of the most popular database programs today. Updated to reflect software changes, this book includes practical examples and user-friendly language that speed learning and productivity. Included are timesaving shortcuts and helpful on-screen illustrations. 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
Modeling and Analysis of Fault-Tolerant Multiple Processor Systems
Authors: Kishor Trivedi, Robert Geist
Venue:  (1985)

We present the key issues and some of the solutions in the modeling and analysis of fault-tolerant multiple processor systems. Performance modeling, reliability modeling and the combined evaluation of performance and reliability are discussed. A simple example is used to illustrate these models. Important references are given for further study.
Experimentation in CPU Control with Real-Time Java
Authors: Gerasimos Xydas, Jerome Tassel
Venue: Proceedings of the Third IEEE International Symposium on Object-Oriented Real-Time Distributed Computing (2000)

In order to achieve end-to-end QoS provision, QoS control must be offered in all layers of the Internet stack, including sending and receiving end-hosts. New emerging IETF protocols deal with network QoS, but end-system resource control is also required to achieve end-to-end QoS.Multimedia networked applications have streams with time critical constraints, thus the performance of the involved elements during the delivery of such stream must be predictable and controllable. Furthermore, applications are written without resource sharing in mind, while code mobility prevents from a-priori knowledge of the target execution environment in order to set exact time needs. The portability of real-time code is subject to the ability to adapt to the run-time execution environment, which in turn has to be shielded from possible "bad-code" in a guest application.In this work, we deal with a CPU manager (namely QoS Animator) that facilitates portable real-time code written in Java language. QoS Animator extends traditional Java facilities for real-time applications by controlling CPU resources based on a two-level Rate Monotonic (RM) simulation. Furthermore, as the target execution environment is unknown during development, QoS Animator calculates the execution time of tasks during runtime, while preventing tasks from overusing the CPU.To enhance the real-time facilities of a widely used OS (Windows NT), the prototype makes use of a Low Frequency Filter, which accommodates time delays caused by unscheduled asynchronous events. The results of the experiments show that using this QoS manager the soft real-time constraints of some Java tasks can be met. QoS Animator offers a simple API that allows applications to use cross platform attributes in order to include time critical sections in their code.
Three-dimensional medical image segmentation using a graph-theoretic energy-minimisation approach
Authors: Brian Parker
Venue: Proceedings of the Pan-Sydney area workshop on Visual information processing - Volume 11 (2001)

A new graph algorithm for multiscale segmentation of three-dimensional medical data sets is presented. It is a three-dimensional generalisation of an existing two-dimensional Mumford-Shah region-merging segmentation algorithm. The Mumford-Shah functional formulation leads to improved segmentation results compared to alternative approaches; the graph theoretic approach yields improved performance and simplified data structures; and the automated stopping estimation allows a fully non-supervised algorithm with no tuning parameters required (except for an optional parameter to select the depth of segmentation).