ppxscal/embedding_network huggingface dataset:
Regularized Combined Field Integral Equations
Authors: A. Buffa, R. Hiptmair
Venue: Numerische Mathematik (2005)

Many boundary integral equations for exterior boundary value problems for the Helmholtz equation suffer from a notorious instability for wave numbers related to interior resonances. The so-called combined field integral equations are not affected. However, if the boundary &#x0393; is not smooth, the traditional combined field integral equations for the exterior Dirichlet problem do not give rise to an L2(&#x0393;)-coercive variational formulation. This foils attempts to establish asymptotic quasi-optimality of discrete solutions obtained through conforming Galerkin boundary element schemes.This article presents new combined field integral equations on two-dimensional closed surfaces that possess coercivity in canonical trace spaces. The main idea is to use suitable regularizing operators in the framework of both direct and indirect methods. This permits us to apply the classical convergence theory of conforming Galerkin methods.
Ad Hoc, self-supervising peer-to-peer search networks
Authors: Brian F. Cooper, Hector Garcia-Molina
Venue: ACM Transactions on Information Systems (TOIS) (2005)

Peer-to-peer search networks are a popular and widely deployed means of searching massively distributed digital information repositories. Unfortunately, as such networks grow, peers may become overloaded processing messages from other peers. This article examines how to reduce the load on nodes in P2P networks by allowing them to self-organize into a relatively efficient network, and then self-tune to make the network even more efficient. Two local operations used by a peer are introduced: connect(), in which the peer forms an ad hoc search or index link to another peer, and break(), in which the peer breaks a link that is producing too much load. By replacing fixed rules with dynamic local decision-making, such &ldquo;self-supervising&rdquo; networks can better adjust to network conditions. Different ways to implement connect() and break() are described, and the network structures that form under different configurations are examined. Simulation results indicate that the ad hoc networks formed using the described techniques are more efficient than popular supernode topologies for several important scenarios. Results for the fault tolerance and search latency of such ad hoc networks are also presented.
Multiple Errors Produced by Single Upsets in FPGA Configuration Memory: A Possible Solution
Authors: Matteo Sonza Reorda, Luca Sterpone, Massimo Violante
Venue: Proceedings of the 10th IEEE European Symposium on Test (2005)

The very high integration levels reached by SRAM-based Field Programmable Gate Arrays (FPGAs) lead to high occurrence rate of Single Event Upsets (SEUs) in their configuration memory, which can produce multiple errors affecting routing resources. Based on detailed analysis of this phenomenon, we devised a reliability-oriented place and route algorithm able to significantly improve the reliability of SRAM-based FPGAs with limited costs in terms of performance degradation and resource occupation. To evaluate the effectiveness of the new algorithm we performed extensive fault injection experiments.
Signed Distance Computation Using the Angle Weighted Pseudonormal
Authors: J. Andreas Baerentzen Henrik Aanaes
Venue: IEEE Transactions on Visualization and Computer Graphics (2005)

The normals of closed, smooth surfaces have long been used to determine whether a point is inside or outside such a surface. It is tempting to also use this method for polyhedra represented as triangle meshes. Unfortunately, this is not possible since, at the vertices and edges of a triangle mesh, the surface is not C^1 continuous, hence, the normal is undefined at these loci. In this paper, we undertake to show that the angle weighted pseudonormal (originally proposed by Thürmer and Wüthrich and independently by Séquin) has the important property that it allows us to discriminate between points that are inside and points that are outside a mesh, regardless of whether a mesh vertex, edge, or face is the closest feature. This inside-outside information is usually represented as the sign in the signed distance to the mesh. In effect, our result shows that this sign can be computed as an integral part of the distance computation. Moreover, it provides an additional argument in favor of the angle weighted pseudonormals being the natural extension of the face normals. Apart from the theoretical results, we also propose a simple and efficient algorithm for computing the signed distance to a closed C^0 mesh. Experiments indicate that the sign computation overhead when running this algorithm is almost negligible.
A Conversation with Peter Tippett and Steven Hofmeyr
Authors: Jim Maurer
Venue: Queue (2005)

There have always been similarities and overlap between the worlds of biology and computer science. Nowhere is this more evident than in computer security, where the basic terminology of viruses and infection is borrowed from biomedicine.
Quadratic Convergence of a Primal-Dual Interior Point Method for Degenerate Nonlinear Optimization Problems
Authors: Hiroshi Yamashita, Hiroshi Yabe
Venue: Computational Optimization and Applications (2005)

Recently studies of numerical methods for degenerate nonlinear optimization problems have been attracted much attention. Several authors have discussed convergence properties without the linear independence constraint qualification and/or the strict complementarity condition. In this paper, we are concerned with quadratic convergence property of a primal-dual interior point method, in which Newton's method is applied to the barrier KKT conditions. We assume that the second order sufficient condition and the linear independence of gradients of equality constraints hold at the solution, and that there exists a solution that satisfies the strict complementarity condition, and that multiplier iterates generated by our method for inequality constraints are uniformly bounded, which relaxes the linear independence constraint qualification. Uniform boundedness of multiplier iterates is satisfied if the Mangasarian-Fromovitz constraint qualification is assumed, for example. By using the stability theorem by Hager and Gowda (1999), and Wright (2001), the distance from the current point to the solution set is related to the residual of the KKT conditions.By controlling a barrier parameter and adopting a suitable line search procedure, we prove the quadratic convergence of the proposed algorithm.
The anatomy of a news search engine
Authors: A. Gulli
Venue: Special interest tracks and posters of the 14th international conference on World Wide Web (2005)

Today, news browsing and searching is one of the most important Internet activity. This paper introduces a general framework to build a News search engine by describing Velthune, an academic News search engine available on line.
A class of network optimization methods for planar grid generation
Authors: N. Egidi, P. Maponi
Venue: Applied Numerical Mathematics (2005)

The grid generation problem considers the question of the computation of a grid Q over a given domain Ω from the knowledge of Q on the boundary ∂Ω. It is usually given in terms of the computation of the grid vertices belonging to the interior of Ω, that in the direct optimization formulation are computed as the minimizer of a particular minimization problem. In this paper the grid generation problem is reformulated as a network optimization problem on a particular graph, that is a nonlinear minimum cost flow problem, where in place of the standard Euclidean vector norm is proposed the use of the well-known vector p-norm, where p ≥ 1. Some results coming from our numerical experience on the examples proposed in the Rogue's Gallery of Grids are reported.
Finding bugs is easy
Authors: David Hovemeyer, William Pugh
Venue: ACM SIGPLAN Notices (2004)

Many techniques have been developed over the years to automatically find bugs in software. Often, these techniques rely on formal methods and sophisticated program analysis. While these techniques are valuable, they can be difficult to apply, and they aren't always effective in finding real bugs.Bug patterns are code idioms that are often errors. We have implemented automatic detectors for a variety of bug patterns found in Java programs. In this paper, we describe how we have used bug pattern detectors to find serious bugs in several widely used Java applications and libraries. We have found that the effort required to implement a bug pattern detector tends to be low, and that even extremely simple detectors find bugs in real applications.From our experience applying bug pattern detectors to real programs, we have drawn several interesting conclusions. First, we have found that even well tested code written by experts contains a surprising number of obvious bugs. Second, Java (and similar languages) have many language features and APIs which are prone to misuse. Finally, that simple automatic techniques can be effective at countering the impact of both ordinary mistakes and misunderstood language features.
An electronic learning assistant
Authors: Vladimir Kolovski, Strahil Jordanov, John Galletly
Venue: Proceedings of the 5th international conference on Computer systems and technologies (2004)

In this paper, based on our previous work, we describe the functionality and implementation of a Semantic Web-based e-learning application - an Electronic Learning Assistant (ELA) - with focus on the RDF data model and OWL ontology of the application.
Low-overhead state-retaining elements for low-leakage MTCMOS design
Authors: Pietro Babighian, Luca Benini, Alberto Macii, Enrico Macii
Venue: Proceedings of the 15th ACM Great Lakes symposium on VLSI (2005)

Multi-threshold CMOS (MTCMOS) has shown to be a very effective technique for reducing sub-threshold leakage currents in DSM CMOS designs. Application of the MTC-MOS paradigm to sequential circuits requires the availability of data-retaining elements for storing circuit state during stand-by mode. In this paper we propose two novel circuit schemes for sequential elements featuring low leakage currents in stand-by mode and high-speed/low-dynamic power in active mode. We present post-layout simulation results obtained after parasitic extraction for delay and power of circuits built in 130nm CMOS technology. Our experiments demonstrate several advantages of the proposed schemes over the best previously published solutions.
Some observations on bitTorrent performance
Authors: Ashwin R. Bharambe, Cormac Herley, Venkata N. Padmanabhan
Venue: Proceedings of the 2005 ACM SIGMETRICS international conference on Measurement and modeling of computer systems (2005)

In this paper, we present a simulation-based study of BitTorrent. Our results confirm that BitTorrent performs near-optimally in terms of uplink bandwidth utilization and download time, except under certain extreme conditions. On fairness, however, our work shows that low bandwidth peers systematically download more than they upload to the network when high bandwidth peers are present. We find that the rate-based tit-for-tat policy is not effective in preventing unfairness. We show how simple changes to the tracker and a stricter, block-based tit-for-tat policy, greatly improves fairness, while maintaining high utilization.
TAG: a Tiny AGgregation service for Ad-Hoc sensor networks
Authors: Samuel Madden, Michael J. Franklin, Joseph M. Hellerstein, Wei Hong
Venue: Proceedings of the 5th symposium on Operating systems design and implementationDue to copyright restrictions we are not able to make the PDFs for this conference available for downloading (2002)

We present the Tiny AGgregation (TAG) service for aggregation in low-power, distributed, wireless environments. TAG allows users to express simple, declarative queries and have them distributed and executed efficiently in networks of low-power, wireless sensors. We discuss various generic properties of aggregates, and show how those properties affect the performance of our in network approach. We include a performance study demonstrating the advantages of our approach over traditional centralized, out-of-network methods, and discuss a variety of optimizations for improving the performance and fault-tolerance of the basic solution.
Crystal ball: predicting end-user experience with a digital media adapter
Authors: Cory J. Booth, Paul Sorenson
Venue: CHI '05 extended abstracts on Human factors in computing systems (2005)

Computers are moving out of the home office and into other areas of the home. The problem today is not whether the technology that enables this transition is available, but whether people can use the technology as it is presented today. Unfortunately, for the average user, the initial experience of setting up and using some of the newest and most interesting digital home devices is challenging, at best, and impossible for many. This paper describes a unique research technique that has been used to create tools that predict the end-users' experience when setting up and using a variety of products (Lind & Michalak, 2001; Lind & Michalak, 2002). Most recently, we applied this approach to a new category of products called "Digital Media Adapters" (DMAs). As with its predecessors, this tool not only allows the prediction of an end-users' experience but provides guidance on how to improve their experience.
Managing Flexible Capacity in a Make-to-Order Environment
Authors: Ebru K. Bish, Ana Muriel, Stephan Biller
Venue: Management Science (2005)

Flexible capacity has been shown to be very effective to hedge against forecast errors at the investment stage. In a make-to-order environment, this flexibility can also be used to hedge against variability in customer orders in the short term. For that purpose, production levels must be adjusted each period to match current demands, to give priority to the higher margin product, or to satisfy the closest customer. However, this will result in swings in production, inducing larger order variability at upstream suppliers and significantly higher component inventory levels at the manufacturer. Through a stylized two-plant, two-product capacitated manufacturing setting, we show that the performance of the system depends heavily on the allocation mechanism used to assign products to the available capacity. Although managers would be inclined to give priority to higher-margin products or to satisfy customers from their closest production site, these practices lead to greater swings in production, result in higher operational costs, and may reduce profits.
Periodic Linear Programming with applications to real-time scheduling
Authors: K. Subramani
Venue: Mathematical Structures in Computer Science (2005)

In this paper we introduce a new mathematical modelling technique called Periodic Linear Programming; the periodic properties of Periodic Linear Programs (PLPs) permit the specification of inter-period constraints in embedded systems, in a straightforward and natural manner. We analyse PLPs in which the relationship between program variables is restricted to the class of difference constraints. Our analysis establishes that such PLPs can be reduced to simple linear programs, and hence decided in polynomial time. The class of difference constraints is extremely important from the perspective of embedded systems design, in that it permits the specification of complex timing constraints in real-time specification languages. A PLP can be thought of as a finite-description tool that represents infinite-state systems; although we use this tool purely for the purpose of modelling real-time scheduling problems, PLPs also find applications in other areas, such as concurrency design. In studying this programming paradigm, we develop novel techniques that, to the best of our knowledge, are not part of the literature. We build on the PLP structure to introduce a generalisation called Periodic Quantified Linear Programming; this programming paradigm permits the specification and analysis of uncertainty in the parameters of a PLP. Consequently, a Periodic Quantified Linear Program (PQLP) is the natural modelling tool to capture the requirements of periodic, embedded systems that are characterised by uncertainty in the execution times of processes, periodicity and relative timing constraints. In this paper, we use the PQLP structure to model and solve the periodic version of the zero-clairvoyant scheduling problem. Modelling uncertainty in the problem description is a typical technique used to incorporate a measure of fault-tolerance in the specification.
Distributed system diagnosis of byzantine failures in partially connected multicomputer systems
Authors: V. Yu. Grishin, A. V. Lobanov, V. G. Sirenko
Venue: Automation and Remote Control (2005)

For the most general, so-called byzantine, failures that lie in an arbitrary, "malevolent" behavior of the faulty computer, a method of distributed system diagnosis was proposed. It is applicable to the partially connected multicomputer systems featuring certain structural characteristics and enables the system to detect and identify the manifested failures on its own without an outside aid.
Web log mining with adaptive support thresholds
Authors: Jian-Chih Ou, Chang-Hung Lee, Ming-Syan Chen
Venue: Special interest tracks and posters of the 14th international conference on World Wide Web (2005)

With the fast increase in Web activities, Web data mining has recently become an important research topic. However, most previous studies of mining path traversal patterns are based on the model of a uniform support threshold without taking into consideration such important factors as the length of a pattern, the positions of Web pages, and the importance of a particular pattern, etc. In view of this, we study and apply the Markov chain model to provide the determination of support threshold of Web documents. Furthermore, by properly employing some techniques devised for joining reference sequences, a new mining procedure of Web traversal patterns is proposed in this paper.
Improved range image segmentation by analyzing surface fit patterns
Authors: Jaesik Min, Kevin W. Bowyer
Venue: Computer Vision and Image Understanding (2005)

We propose a new approach to range image segmentation of planar and curved surface scenes. Our method is mainly an extended design of an existing algorithm, which was guided by a framework of performance evaluation. We choose the range segmentation algorithm developed by Jiang and Bunke as our baseline algorithm, which is last and has shown relatively high performance in several experimental performance evaluation studies. We analyze the types of errors made by the algorithm, propose design modifications to decrease the error rate, and experimentally verify that the new approach achieves statistically significant performance improvement. Whereas the baseline algorithm applies the edge-linking uniformly to all edge pixels to segment a region, the modified algorithm selects high potential edge areas in the region by analyzing the surface fit pattern and gives priority of edge-linking to those areas. The contributions of this work are (1) an improved algorithm for segmentation of range images of both planar and curved surface scenes, and (2) a demonstration of using empirical performance evaluation to guide algorithm design and modification to achieve better performance.
The G4-FET: a universal and programmable logic gate
Authors: A. Fijany, F. Vatan, M. Mojarradi, B. Toomarian, B. Blalock, K. Akarvardar, S. Cristoloveanu, P. Gentil
Venue: Proceedings of the 15th ACM Great Lakes symposium on VLSI (2005)

The G4-FET, a four-gate transistor compatible with standard silicon-on-insulator (SOI) CMOS technology, provides unique opportunities as a logic device. Combining both JFET- and MOSFET-like actions within one transistor body, the G4-FET offers two side (lateral) junction-based gates, a top MOS gate, and a MOS back gate that is activated by SOI substrate biasing. The G4-FET's conduction characteristics are controlled by the combined interaction of these four gates. In this paper, the G4-FET is demonstrated as a logic device, resulting in a universal and programmable logic gate that can lead to the design of more efficient logic circuits. As an example, we present a new full adder design based on the G4-FET that is significantly more efficient than conventional designs.
Speed and Search: Designing Organizations for Turbulence and Complexity
Authors: Nicolaj Siggelkow, Jan W. Rivkin
Venue: Organization Science (2005)

We use an innovative technique to examine an enduring but recently neglected question: How do environmental turbulence and complexity affect the appropriate formal design of organizations? We construct an agent-based simulation in which multidepartment firms with different designs face environments whose turbulence and complexity we control. The model's results produce two sets of testable hypotheses. One set pinpoints formal designs that cope well with three different environments: turbulent settings, in which firms must improve their performance speedily; complex environments, in which firms must search broadly; and settings with both turbulence and complexity, in which firms must balance speed and search. The results shed new light on longstanding notions such as equifinality. The other set of hypotheses argues that the impact of individual design elements on speed and search often depends delicately on specific powers granted to department heads, creating effects that run contrary to conventional wisdom and intuition. Ample processing power at the bottom of a firm, for instance, can slow down the improvement and narrow the search of the firm as a whole. Differences arise between our results and conventional wisdom when conventional thinking fails to account for the powers of department heads--powers to withhold information about departmental options, to control decision-making agendas, to veto firmwide alternatives, and to take unilateral action. Our results suggest how future empirical studies of organizational design might be fruitfully coupled with rigorous agent-based modeling efforts.