ppxscal/embedding_network huggingface dataset:
Heavy Traffic Limits for Queues with Many Deterministic Servers
Authors: Predrag Jelenković, Avishai Mandelbaum, Petar Momčilović
Venue: Queueing Systems: Theory and Applications (2004)

Consider a sequence of stationary GI/D/N queues indexed by N&uarr;&infin;, with servers' utilization 1&minus;&beta;/$\sqrt{N}$, &beta;>0. For such queues we show that the scaled waiting times $\sqrt{N}$WN converge to the (finite) supremum of a Gaussian random walk with drift &minus;&beta;. This further implies a corresponding limit for the number of customers in the system, an easily computable non-degenerate limiting delay probability in terms of Spitzer's random-walk identities, and $\sqrt{N}$ rate of convergence for the latter limit. Our asymptotic regime is important for rational dimensioning of large-scale service systems, for example telephone- or internet-based, since it achieves, simultaneously, arbitrarily high service-quality and utilization-efficiency.
Collective Endorsement and the Dissemination Problem in Malicious Environments
Authors: Subramanian Lakshmanan, Deepak J. Manohar, Mustaque Ahamad, H. Venkateswaran
Venue: Proceedings of the 2004 International Conference on Dependable Systems and Networks (2004)

We consider the problem of disseminating an updateknown to a set of servers to other servers in the system viaa gossip protocol.Some of the servers can exhibit maliciousbehavior.We require that only the updates introduced byauthorized clients are accepted by non-malicious servers.Spurious updates, in particular those generated by compromisednodes, are not accepted by non-malicious servers.We take the approach of collective endorsement where eachserver endorses an accepted update by computing a listof message authentication codes with symmetric keys allocatedto it.We use a novel key allocation scheme that allocatesa set of symmetric keys to each participating server tominimize the total number of keys.Our protocol is designed to minimize update diffusiontime.In the absence of faulty nodes, its diffusion time isO(log n), which is the best possible time achieved whennodes only suffer from benign faults.If the actual numberof Byzantine faults experienced during an update's disseminationis f, diffusion time increases to O(log n) + f.Thisis better than the latency of previously known protocols thattake O(log n) + b time, where b is the assumed thresholdthat defines the maximum number of malicious servers thatcan be tolerated rather than f, the actual number of failures.The buffer requirements and message sizes are higherin our protocol than other known protocols, thus it tradesoff memory and bandwidth resources to improve latency.
Extension of ISO 10303, the STEP Standard, for the Exchange of Procedural Shape Models
Venue: Proceedings of the Shape Modeling International 2004 (2004)

The paper describes the status of work aimed at extendingthe international standard ISO 10303 (STEP) to permitthe exchange of procedurally defined shape models betweenCAD systems. Such models are specified by the sequenceof operations used to construct them rather than by the explicitelements they contain. They have the advantage of beingeasy to edit in a receiving system, by contrast with theexplicit models that can be exchanged using current standards,which prove to be inert after transfer. The use of theproposed methodology in the exchange of realistic proceduralshape models of mechanical parts has already beendemonstrated, and a brief account is given of some of thetests that have been performed.
Partitioning crowded virtual environments
Authors: Anthony Steed, Roula Abou-Haidar
Venue: Proceedings of the ACM symposium on Virtual reality software and technology (2003)

We investigate several techniques that partition a crowded virtual environment into regions that can be managed by separate servers or mapped onto different multicast groups. When constructing a partitioning, we attempt to minimize overhead of the partitioning with respect to network management, whilst maintaining a bound on the number of entities that are mapped to any particular server or group.We compare several partitioning schemes: quad tree, k-d tree unconstrained, k-d tree constrained, and region growing. With our simulations of a crowded virtual environment modelled on a part of central London, we find that the region growing technique give the best overall results.
No Helly Theorem for Stabbing Translates by Lines in R3
Authors: Andreas Holmsen, Jiri Matousek
Venue: Discrete Computational Geometry (2004)

For each $n>2$ we construct a convex body $K\subset {\Bbb R}^3$ and a finite family ${\cal F}$ of disjoint translates of $K$ such that any $n-1$ members ${\cal F}$ admit a line transversal, but ${\cal F}$ has no line transversal.
Promoter Recognition for E. coli DNA Segments by Independent Component Analysis
Authors: Yasuo Matsuyama, Ryo Kawamura
Venue: Proceedings of the 2004 IEEE Computational Systems Bioinformatics Conference (2004)

A new method for E. coli DNA segment classification on promoters and non-promoters is presented. The algorithm is based on the Independent Component Analysis (ICA). Since the DNA segments are composed of discrete symbols, this paper contains two major steps: (1) Position-dependent transformation of DNA segments to real number sequences, and (2) Applications of the ICA to the E. coli promoter recognition. These steps are related to each other. Therefore, algorithmic explanations are given in detail while referring mutually. The automatic precision of 93.7% is obtained. Since the presented method allows threshold adjustments, twilight-zone data can be further cross-checked individually so that false negatives are reduced.
Sweepers: Swept User-Defined Tools for Modeling by Deformation
Venue: Proceedings of the Shape Modeling International 2004 (2004)

We present sweepers, a new class of space deformationssuitable for interactive virtual sculpture. The artistdescribes a basic deformation as a path through which atool is moved. Our tools are simply shapes, subsets of 3Dspace. So we can use shapes already created as customizedtools tomakemore complex shapes or to simplify themodelingprocess.When a tool is moved it causes a deformation of theworking shape along the path of the tool. This is in accordancewith a clay modeling metaphor and easy to understandand predict.More complicated deformations areachieved by using several tools simultaneously in the sameregion.It is desirable that deformations for modeling areýfoldover-freeý, that is parts of deformed space cannotoverlap so that the deformations are reversible. Thereare good intuitive reasons to believe that our deformationsare foldover-free but we have not yet completed aproof.We have an efficient formulation for a single tool followinga simple path (translation, scaling or rotation) andwe can demonstrate the effects of multiple tools used simultaneously.For representing shapes,we present amesh refinementand decimation algorithm that takes advantage of the definitionof our deformations. The prototype implementationdescribed has been used to create a variety of modelsquickly and conveniently.
Symbolic Model Checking the Knowledge of the Dining Cryptographers
Authors: Ron van der Meyden, Kaile Su
Venue: Proceedings of the 17th IEEE workshop on Computer Security Foundations (2004)

This paper describes the application of symbolic techniques(in particular, OBDD's) to model checking specificationsin the logic of knowledge for an agent operating withsynchronous perfect recall in an environment of which it hasincomplete knowledge. It discusses the application of thesetechiques to the verification of a security protocol: Chaum'sDining Cryptographers protocol, which provides a mechanismfor anonymous broadcast.
A Trade-off Oriented Placement Tool
Authors: Huaiyu Xu, Maogang Wang, Bo-Kyung Choi, Majid Sarrafzadeh
Venue: Proceedings of the 2003 IEEE/ACM international conference on Computer-aided design (2003)

High quality placement results are always produced at the cost ofsignificant runtimes. In this paper, we study the trade-offbetween the overall quality and the runtime for standard-cellplacement problems. We implemented and studied a class ofschemes to achieve the runtime vs. quality trade-off. Wedeveloped a new trade-off oriented placement tool (TOOP)which is controlled by decision trees. TOOP can adjust itselfbased on user's requests and netlist properties. Compared toCadence QPlace, even the fastest mode of TOOP (lowest quality)can produce placements with similar or better layout. TOOP alsoshows much stronger ability to produce routable placement whencompared to Capo.
Trust Negotiations: Concepts, Systems, and Languages
Authors: Elisa Bertino, Elena Ferrari, Anna Squicciarini
Venue: Computing in Science and Engineering (2004)

Trust negotiation is a promising approach for establishing trust in open systems like the Internet, where sensitive interactions may often occur among entities with no prior knowledge of each other. In this article, the authors present a model for trust negotiation systems, and delineate the desiderata that ideal trust negotiation systems should satisfy. In defining trust negotiation requirements, they consider two different issues, policy language requirements and system requirements. They then survey the most interesting proposals that have been presented so far and evaluate them with respect to the identified requirements. Finally, we outline future research directions and identify the open issues that still have to be explored.
Merging R-trees
Authors: Vasilis Vasaitis, Alexandros Nanopoulos, Panayiotis Bozanis
Venue: Proceedings of the 16th International Conference on Scientific and Statistical Database Management (2004)

R-trees, since their introduction in 1984, have beenproven to be one of the most well-behaved practical datastructures for accommodating dynamic massive sets of geometricobjects and conducting a diverse set of queries onsuch data-sets in real-world applications. In this paper weintroduce a new technique for merging two R-trees into anew one of very good quality. Our method avoids boththe employment of bulk insertions and the solution of bulk-loading,from scratch, the new tree using the data of theoriginal trees. Additionally, unlike previous approaches,it does not make any assumptions about data-set distributions.Experimental results provide evidence on the runtimeefficiency of our method and illustrate the good query performanceof the produced indices.
Comparative Analysis of Gene Sets in the Gene Ontology Space under the Multiple Hypothesis Testing Framework
Authors: Sheng Zhong, Lu Tian, Cheng Li, Kai-Florian Storch, Wing H. Wong
Venue: Proceedings of the 2004 IEEE Computational Systems Bioinformatics Conference (2004)

The Gene Ontology (GO) resource can be used as a powerful tool to uncover the properties shared among, and specific to, a list of genes produced by high-throughput functional genomics studies, such as microarray studies. In the comparative analysis of several gene lists, researchers maybe interested in knowing which GO terms are enriched in one list of genes but relatively depleted in another. Statistical tests such as Fisherýs exact test or Chi-square test can be performed to search for such GO terms. However, because multiple GO terms are tested simultaneously, individual p-values from individual tests do not serve as good indicators for picking GO terms. Furthermore, these multiple tests are highly correlated, usual multiple testing procedures that work under an independence assumption are not applicable. In this paper we introduce a procedure, based on False Discovery Rate (FDR), to treat this correlated multiple testing problem. This procedure calculates a moderately conserved estimator of q-value for every GO term. We identify the GO terms with q-values that satisfy a desired level as the significant GO terms. This procedure has been implemented into the GoSurfer software. GoSurfer is a windows based graphical data mining tool. It is freely available at http://www.gosurfer.org
Clusters for nothing and nodes for free
Authors: Alexander Perry, Hoke Trammell, David Haynes
Venue: Linux Journal (2004)

The processing power you need for big nightly jobs is all around you, and the desktop users won't miss it.
Tools for devising cellular automata in the hyperbolic 3D space
Authors: Maurice Margenstern, Gencho Skordev
Venue: Fundamenta Informaticae (2003)

The study of cellular automata (CA) on tilings of hyperbolic plane was initiated in [13]. Appropriate tools were developed which allow linear algorithms to implement cellular automata on the tiling of the hyperbolic plane with the regular rectangular pentagon.In this paper we tackle the problem of devising similar tools in the case of the 3D hyperbolic space. The tools are given for the rectangular dodecahedral tiling of the 3D hyperbolic space. We give an algorithm which computes all needed information from the number of a cell. The algorithm is cubic in time and quadratic in space.
Real-time rendering of woven clothes
Authors: Neeharika Adabala, Nadia Magnenat-Thalmann, Guangzheng Fei
Venue: Proceedings of the ACM symposium on Virtual reality software and technology (2003)

Virtual environments containing humans moving and performing actions in real time are ubiquitous in computer graphics applications. Such characters are often clothed in woven fabrics. This paper presents a technique for visualizing woven clothes in real time, while optimizing the realistic appearance. The proposed approach supports rendering of complex weave patterns by adopting Weaving Information File (WIF), a standard from textile Computer Aided Design (CAD) for representing the grammar of weaving. We develop a realistic rendering scheme by combining the grammar representation obtained from the WIF with a procedural thread texture, a suitable cloth Bi-directional Reflectance Distribution Function (BRDF) and horizon maps. We employ the multi-texturing approach to meet the real time constraint. Thus our approach to visualizing woven clothes begins from weaving grammar specifications and converts them into textures that can be applied on clothes. We demonstrate the versatility of the proposed approach with examples.
Beyond formal learning: informal community eLearning
Authors: John Cook, Matt Smith
Venue: Computers Education (2004)

The goal of the study described in this paper was to gain an improved understanding of the social context of UK online centres and issues around the creation and exchange of knowledge within and between online community centres. Grounded theory and a pilot study were used to guide our research. The key findings of our research were (i) an elucidation of the goals that drive individuals to improve or share knowledge with others and (ii) the high level concept categories of life-cycles provided us with the basis for a model which characterises formation of, and participation in, informal learning communities. Indeed, the high level concept categories that emerged as strongly supported in our analysis point to the need for interdisciplinary theorising in this area. In this paper, we will: (a) give a summary of what we mean by informal community eLearning, (b) illustrate the key issues with results from a study of UK online centres, and (c) make recommendations for future theorising and research directions.
Blind Channel Estimation in Multicode CDMA Using Multiantenna Receiver
Authors: Maarit Melvasalo, Visa Koivunen
Venue: Wireless Personal Communications: An International Journal (2004)

In this paper blind channel estimation methods for long code CDMA system with multicode transmission are proposed. By allocating multiple codes, higher data rates may be provided to a user. Blind channel estimation allows reducing pilot signaling. Hence, higher effective data rates may be achieved and larger sample support may be obtained by using both the information symbols and known pilot symbols for channel estimation. Algorithms are extended to multi-antenna receiver which further improves the performance. The performance of the algorithms is studied in extensive simulations using WCDMA system model. The effects of code selection, interference and noise, number of antennas, antenna correlation are considered using frequency selective channel models. The proposed methods are more robust in the face of interference and code selection than the well-known subspace method in \cite{WF99}. The computational complexity is lower as well.
Plumber
Venue: ACM SIGGRAPH 2003 video review on Animation theater program: part 1 - Volume 145 (2003)

Mario is determined to fix his leaky tap. All shots of Mario involve dynamically-simulated clothing, and every frame has been rendered with a mix of traditional/advanced lighting techniques and global photon mapping. Copyright held by creator.
Memory Ordering: A Value-Based Approach
Authors: Harold W. Cain, Mikko H. Lipasti
Venue: Proceedings of the 31st annual international symposium on Computer architecture (2004)

Conventional out-of-order processors employ a multi-ported,fully-associative load queue to guarantee correctmemory reference order both within a single thread of executionand across threads in a multiprocessor system. Asimprovements in process technology and pipelining lead tohigher clock frequencies, scaling this complex structure toaccommodate a larger number of in-flight loads becomesdifficult if not impossible. Furthermore, each access to thiscomplex structure consumes excessive amounts of energy.In this paper, we solve the associative load queue scalabilityproblem by completely eliminating the associative loadqueue. Instead, data dependences and memory consistencyconstraints are enforced by simply re-executing loadinstructions in program order prior to retirement. Usingheuristics to filter the set of loads that must be re-executed,we show that our replay-based mechanism enables a simple,scalable, and energy-efficient FIFO load queue designwith no associative lookup functionality, while sacrificingonly a negligible amount of performance and cache bandwidth.
The integration of an interior-point cutting plane method within a branch-and-price algorithm
Authors: Samir Elhedhli, Jean-Louis Goffin
Venue: Mathematical Programming: Series A and B (2004)

This paper presents a novel integration of interior point cutting plane methods within branch-and-price algorithms. Unlike the classical method, columns are generated at a &#x2018;&#x2018;central&#x2019;&#x2019; dual solution by applying the analytic centre cutting plane method (ACCPM) on the dual of the full master problem. First, we introduce some modifications to ACCPM. We propose a new procedure to recover primal feasibility after adding cuts and use, for the first time, a dual Newton&#x2019;s method to calculate the new analytic centre after branching. Second, we discuss the integration of ACCPM within the branch-and-price algorithm. We detail the use of ACCPM as the search goes deep in the branch and bound tree, making full utilization of past information as a warm start. We exploit dual information from ACCPM to generate incumbent feasible solutions and to guide branching. Finally, the overall approach is implemented and tested for the bin-packing problem and the capacitated facility location problem with single sourcing. We compare against Cplex-MIP 7.5 as well as a classical branch-and-price algorithm.
Stability-based validation of clustering solutions
Authors: Tilman Lange, Volker Roth, Mikio L. Braun, Joachim M. Buhmann
Venue: Neural Computation (2004)

Data clustering describes a set of frequently employed techniques in exploratory data analysis to extract "natural" group structure in data. Such groupings need to be validated to separate the signal in the data from spurious structure. In this context, finding an appropriate number of clusters is a particularly important model selection question. We introduce a measure of cluster stability to assess the validity of a cluster model. This stability measure quantifies the reproducibility of clustering solutions on a second sample, and it can be interpreted as a classification risk with regard to class labels produced by a clustering algorithm. The preferred number of clusters is determined by minimizing this classification risk as a function of the number of clusters. Convincing results are achieved on simulated as well as gene expression data sets. Comparisons to other methods demonstrate the competitive performance of our method and its suitability as a general validation tool for clustering solutions in real-world problems.
Generalization Error Bounds for Threshold Decision Lists
Authors: Martin Anthony
Venue: The Journal of Machine Learning Research (2004)

In this paper we consider the generalization accuracy of classification methods based on the iterative use of linear classifiers. The resulting classifiers, which we call threshold decision lists act as follows. Some points of the data set to be classified are given a particular classification according to a linear threshold function (or hyperplane). These are then removed from consideration, and the procedure is iterated until all points are classified. Geometrically, we can imagine that at each stage, points of the same classification are successively chopped off from the data set by a hyperplane. We analyse theoretically the generalization properties of data classification techniques that are based on the use of threshold decision lists and on the special subclass of multilevel threshold functions. We present bounds on the generalization error in a standard probabilistic learning framework. The primary focus in this paper is on obtaining generalization error bounds that depend on the levels of separation---or margins---achieved by the successive linear classifiers. We also improve and extend previously published theoretical bounds on the generalization ability of perceptron decision trees.
Nature and location of interface traps in RF LDMOS due to hot carriers
Authors: T. Nigam, A. Shibib, S. Xu, H. Safar, L. Steinberg
Venue: Microelectronic Engineering (2004)

In this paper, the nature and location of hot carrier induced defects is studied for N-channel LDMOS (Laterally Diffused MOS) transistors. These devices are used in wireless base stations and typically operate under high drain bias of 25-30 V, making them highly susceptible to hot carrier injection. In this work, the improvement in hot carrier induced degradation by means of a dummy gate is presented. Using the charge pumping technique, it is demonstrated that, (1) significant electron trapping in the LDD region occurs for devices without a dummy gate in contrast to devices with a dummy gate. (2) For devices with a dummy gate interface traps are preferentially generated in the LDD region.
Ontology Based Interactive Graphic Environment for Product Presentation
Authors: Ioannis Tsampoulatidis, Georgios Nikolakis, Dimitrios Tzovaras, Michael G. Strintzis
Venue: Proceedings of the Computer Graphics International (2004)

This paper proposes an innovative environment forpresenting products through the Internet using modernvisualization techniques and providing high level ofinteraction with the user. The environment consists ofthree main modules, namely a) the scene-authoringtool, b) the interactive scene-viewer and c) theassembly-demonstration tool. These modules arebound together with the utilization of a robustontology-based knowledge management system.
The approximate inverse in action III: 3D-Doppler tomography
Authors: Andreas Rieder, Thomas Schuster
Venue: Numerische Mathematik (2004)

The approximate inverse is a powerful tool for solving first kind operator equations in a stable way. Its abstract convergence and stability theory developed in our articles [SIAM J. Numer. Anal., 37, 1909-1929,2000] and [Math. Comp., 72, 1399-1415, 2003] is applied to the reconstruction problem of 3D-vector field tomography resulting in a reconstruction algorithm of filtered backprojection type. For an analytically computed reconstruction filter (reconstruction kernel) convergence with rates as well as the regularization property are established.