ppxscal/embedding_network huggingface dataset:
A queueing system for modeling a file sharing principle
Authors: Florian Simatos, Philippe Robert, Fabrice Guillemin
Venue: ACM SIGMETRICS Performance Evaluation Review (2008)

We investigate in this paper the performance of a simple file sharing principle. For this purpose, we consider a system composed of N peers becoming active at exponential random times; the system is initiated with only one server offering the desired file and the other peers after becoming active try to download it. Once the file has been downloaded by a peer, this one immediately becomes a server. To investigate the transient behavior of this file sharing system, we study the instant when the system shifts from a congested state where all servers available are saturated by incoming demands to a state where a growing number of servers are idle. In spite of its apparent simplicity, this queueing model (with a random number of servers) turns out to be quite difficult to analyze. A formulation in terms of an urn and ball model is proposed and corresponding scaling results are derived. These asymptotic results are then compared against simulations.
Balking and reneging in m/g/s systems exact analysis and approximations
Authors: Liqiang Liu, Vidyadhar g. Kulkarni
Venue: Probability in the Engineering and Informational Sciences (2008)

We consider the virtual queuing time (vqt, also known as work-in-system, or virtual-delay) process in an M/G/s queue with impatient customers. We focus on the vqt-based balking model and relate it to reneging behavior of impatient customers in terms of the steady-state distribution of the vqt process. We construct a single-server system, analyze its operating characteristics, and use them to approximate the multiserver system. We give both analytical results and numerical examples. We conduct simulation to assess the accuracy of the approximation.
Evasion of multiple target in three-dimensional space
Authors: T. G. Abramyants, E. P. Maslov, V. P. Yakhno
Venue: Automation and Remote Control (2008)

Consideration was given to the differential game of one pursuer against a group of one true and one false target in the three-dimensional space where the concordant targets solve the problem of evasion of the true target from being detected by the pursuer.
Analyzing DISH for multi-channel MAC protocols in wireless networks
Authors: Tie Luo, Mehul Motani, Vikram Srinivasan
Venue: Proceedings of the 9th ACM international symposium on Mobile ad hoc networking and computing (2008)

For long, node cooperation has been exploited as a data relaying mechanism. However, the wireless channel allows for much richer interaction between nodes. One such scenario is in a multi-channel environment, where transmitter-receiver pairs may make incorrect decisions (e.g., in selecting channels) but idle neighbors could help by sharing information to prevent undesirable consequences (e.g., data collisions). This represents a Distributed Information SHaring (DISH) mechanism for cooperation and suggests new ways of designing cooperative protocols. However, what is lacking is a theoretical understanding of this new notion of cooperation. In this paper, we view cooperation as a network resource and evaluate the availability of cooperation via a metric, pco, the probability of obtaining cooperation. First, we analytically evaluate pco in the context of multi-channel multi-hop wireless networks. Second, we verify our analysis via simulations and the results show that our analysis accurately characterizes the behavior of pco as a function of underlying network parameters. This step also yields important insights into DISH with respect to network dynamics. Third, we investigate the correlation between pco and network performance in terms of collision rate, packet delay, and throughput. The results indicate a near-linear relationship, which may significantly simplify performance analysis for cooperative networks and suggests that pco be used as an appropriate performance indicator itself. Throughout this work, we utilize, as appropriate, three different DISH contexts - model-based DISH, ideal DISH, and real DISH - to explore pco.
Focused prefetching: performance oriented prefetching based on commit stalls
Authors: R. Manikantan, R. Govindarajan
Venue: Proceedings of the 22nd annual international conference on Supercomputing (2008)

Loads that miss in L1 or L2 caches and waiting for their data at the head of the ROB cause significant slow down in the form of commit stalls. We identify that most of these commit stalls are caused by a small set of loads, referred to as LIMCOS (Loads Incurring Majority of COmmit Stalls). We propose simple history-based classifiers that track commit stalls suffered by loads to help us identify this small set of loads. We study an application of these classifiers to prefetching. The classifiers are used to train the prefetcher to focus on the misses suffered by LIMCOS. This, referred to as focused prefetching, results in a 9.8% gain in IPC over naive GHB based delta correlation prefetcher along with a 20.3% reduction in memory traffic for a set of 17 memory-intensive SPEC2000 benchmarks. Another important impact of focused prefetching is a 61% improvement in the accuracy of prefetches. We demonstrate that the proposed classification criterion performs better than other existing criteria like criticality and delinquent loads. Also we show that the criterion of focusing on commit stalls is robust enough across cache levels and can be applied to any prefetcher without any modifications to the prefetcher.
A Reconfigurable Distributed Broker Infrastructure for Publish Subscribe Based MANET
Authors: Mayank Pandey, Banshi Dhar Chaudhary
Venue: Proceedings of the 2008 IEEE International Conference on Sensor Networks, Ubiquitous, and Trustworthy Computing (sutc 2008) (2008)

Publish-Subscribe communication paradigm is an attractive alternative for MANET because of its anonymous, asynchronous and decoupled behavior. A broker is a dominant component of this paradigm and its design is non-trivial in MANET due to unpredictable mobility of nodes. In this paper, we present an algorithm to establish a reconfigurable, distributed network of brokers, facilitating guaranteed communication between mobile publisher and subscriber. Our approach dynamically elects a set of brokers, such that every non-broker node has a broker in its range. These brokers subsequently establish connection with their neighbor brokers, ensuring connectivity among them. Simulation results indicate that for a given node density the number of brokers in network becomes stable after initial fluctuation. Further, number of brokers decreases with increase in node density. The results also indicate that number of brokers remain stable up to a certain mobility speed and tend to fluctuate only at very high speed.
A Framework Supporting User-Specific Services in RFID Systems
Authors: Chin-Ling Chen
Venue: Proceedings of the Fifth IEEE International Conference on Wireless, Mobile, and Ubiquitous Technology in Education (2008)

In this paper, we propose a multi-mode user agent system that integrates with Radio Frequency Identification (RFID) and kind of context we define to detect the location of the users. The users can dynamically deploy the services they want based on both active and passive identification framework. The multi-mode UA is in charge of monitoring the current location status of users and providing the possible digital services for the specified users.
Constructing an enterprise ontology for an automotive supplier
Authors: Eva Blomqvist, Annika Öhgren
Venue: Engineering Applications of Artificial Intelligence (2008)

This paper presents experiences and conclusions from ontology engineering applied in the automotive suppliers domain. The work focuses on construction of enterprise ontologies to support structuring of enterprise information and knowledge management. Two methods for ontology construction, developed by previous research activities, were used in parallel when developing an ontology for a company in automotive supplier industries. One method is automatic and the other method is a manual approach. A conclusion was that the developed ontologies complemented each other well and therefore the decision was made to merge them for use in the project. The resulting ontology will now be used in several pilot applications.
Updating the QR decomposition of block tridiagonal and block Hessenberg matrices
Authors: Martin H. Gutknecht, Thomas Schmelzer
Venue: Applied Numerical Mathematics (2008)

We present an efficient block-wise update scheme for the QR decomposition of block tridiagonal and block Hessenberg matrices. For example, such matrices come up in generalizations of the Krylov space solvers MinRes, SymmLQ, GMRes, and QMR to block methods for linear systems of equations with multiple right-hand sides. In the non-block case it is very efficient (and, in fact, standard) to use Givens rotations for these QR decompositions. Normally, the same approach is also used with column-wise updates in the block case. However, we show that, even for small block sizes, block-wise updates using (in general, complex) Householder reflections instead of Givens rotations are far more efficient in this case, in particular if the unitary transformations that incorporate the reflections determined by a whole block are computed explicitly. Naturally, the bigger the block size the bigger the savings. We discuss the somewhat complicated algorithmic details of this block-wise update, and present numerical experiments on accuracy and timing for the various options (Givens vs. Householder, block-wise vs. column-wise update, explicit vs. implicit computation of unitary transformations). Our treatment allows variable block sizes and can be adapted to block Hessenberg matrices that do not have the special structure encountered in the above mentioned block Krylov space solvers.
Icetools: A full Stokes finite element model for glaciers
Authors: A. H. Jarosch
Venue: Computers Geosciences (2008)

Detailed studies of glacier flow and deformation of ice require high-resolution numerical modeling. The model presented in this paper, icetools, solves the Stokes equation including all components of the stress tensor, termed full Stokes, with the finite element method to enable such detailed studies. Icetools is capable of running in parallel on computational clusters providing the computing power for large-scale simulations. Two different numerical tests were performed to demonstrate the capability of the model; (1) a comparison with the analytical solution for gravity driven plane flow down an inclined plane, and (2) flow over a Gaussian-shaped bed disturbance in comparison with the analytical transfer functions for this case. The second test involves time evolution of the surface geometry from an initially uniformly sloping surface. A linear rheology medium with a viscosity of 8x10^1^3Pas and a non-linear medium with Glen rheology exponent n=3 and rate factor of A=23x10^-^1^6s^-^1kPa^-^3 were studied. Both correlate well with the analytical solution and reach steady state, defined as when the maximum vertical movement drops below 5x10^-^5 times the mean ice thickness per year, after 282 years for the linear case and 135 years for the non-linear case, respectively.
Interference of neodymium magnets with cardiac pacemakers and implantable cardioverter-defibrillators: An in vitro study
Authors: Salome Ryf, Thomas Wolber, Firat Duru, Roger Luechinger
Venue: Technology and Health Care (2008)

Permanent magnets may interfere with the function of cardiac pacemakers and implantable cardioverter-defibrillators (ICDs). Neodymium-iron-boron (NdFeB) magnets have become widely available in recent years and are incorporated in various articles of daily life. We conducted an in-vitro study to evaluate the ability of NdFeB magnets for home and office use to cause interference with cardiac pacemakers and ICDs. The magnetic fields of ten NdFeB magnets of different size and shape were measured at increasing distances beginning from the surface until a field-strength (B-field) value of 0.5 mT was reached. Furthermore, for each magnet the distance was determined at which a sample pacemaker switched from magnet mode to normal mode. Depending on the size and remanence of individual magnets, a B-field value of 0.5 mT was found at distances ranging from 1.5 cm to 30 cm and a value of 1 mT at distances from 1 cm to 22 cm. The pacemaker behavior was influenced at distances from 1 cm to 24 cm. NdFeB magnets for home and office use may cause interference with cardiac pacemakers and ICDs at distances up to 24 centimeters. Patient education and product declarations should include information about the risk associated with these magnets.
A medium-grain reconfigurable architecture for DSP: VLSI design, benchmark mapping, and performance
Authors: Mitchell J. Myjak, José G. Delgado-Frias
Venue: IEEE Transactions on Very Large Scale Integration (VLSI) Systems (2008)

Reconfigurable hardware has become a well-accepted option for implementing digital signal processing (DSP). Traditional devices such as field-programmable gate arrays offer good fine-grain flexibility. More recent coarse-grain reconfigurable architectures are optimized for word-length computations. We have developed a medium-grain reconfigurable architecture that combines the advantages of both approaches. Modules such as multipliers and adders are mapped onto blocks of 4-bit cells. Each cell contains a matrix of lookup tables that either implement mathematics functions or a random-access memory. A hierarchical interconnection network supports data transfer within and between modules. We have created software tools that allow users to map algorithms onto the reconfigurable platform. This paper analyzes the implementation of several common benchmarks, ranging from floating-point arithmetic to a radix-4 fast fourier transform. The results are compared to contemporary DSP hard-ware.
Designing an Online Virtual World for Learning and Training
Authors: Dennis Cheek, Henry Kelly
Venue: Proceedings of the Fifth IEEE International Conference on Wireless, Mobile, and Ubiquitous Technology in Education (2008)

Online virtual worlds are being rapidly adopted for entertainment, commerce, and social networking purposes. This paper describes the efforts and challenges of using these platforms for learning and training purposes.
A set of novel correlation tests for nonlinear system variables
Authors: L. F. Zhang, Q. M. Zhu, A. Longden
Venue: International Journal of Systems Science (2007)

A set of novel correlation tests using omni-directional cross-correlation functions (ODCCFs), which are based on the first order cross-correlation functions (CCF), are proposed in the present study to comprehensively detect nonlinear relationships between variables. Then the ODCCFs are combined into a set of concise formulations to provide better illustration of detected correlations and reduce the number of correlation plots. Compared to the other approaches, the new methodology brings much more power in detection of nonlinear correlations. The efficiency and effectiveness of the new algorithm are demonstrated through simulation studies and comparisons with other linear and nonlinear correlation tests. The results can be widely applied in many relevant fields.
Relations of attribute reduction between object and property oriented concept lattices
Authors: Xia Wang, Wenxiu Zhang
Venue: Knowledge-Based Systems (2008)

As one of the basic problems of knowledge discovery and data analysis, knowledge reduction can make the discovery of implicit knowledge in data easier and the representation simpler. In this paper, relations of attribute reduction between object and property oriented formal concept lattices are discussed. And beautiful results are obtained that attribute reducts and attribute characteristics in the two concept lattices are the same based on new approaches to attribute reduction by means of irreducible elements. It turns out to be meaningful and effective in dealing with knowledge reduction, as attribute reducts and attribute characteristics in the object and property oriented formal concept lattices can be acquainted by only investigating one of the two concept lattices.
Multi-hop clustering based on neighborhood benchmark in mobile ad-hoc networks
Authors: Stephen S. Yau, Wei Gao
Venue: Mobile Networks and Applications (2007)

Large-scale mobile ad-hoc networks require flexible and stable clustered network structure for efficient data collection and dissemination. In this paper, a technique is presented to construct multi-hop clusters with balanced sizes, based on the neighborhood benchmark (NB) to quantify the connectivity and link stability of mobile nodes. By exploiting autonomous clusterhead selection and a specialized handshake process with the clusterheads, the nodes with highest NB scores are selected as clusterheads and all the clusters constructed are connected. The deviation of cluster sizes is kept small using a partial probability-based approach. Our technique generates highly stable multi-hop clusters with low overhead, and provides the flexibility of controlling the cluster radius adaptively for various network applications.
Design of a DICOM image-based program for estimating patient exposure dose in computed tomography
Authors: Shuji Yamamoto, Tetsuya Horiuchi, Junko Sekiguchi, Shigeo Wada, Mitsuru Komizu, Takami Yamaguchi
Venue: Technology and Health Care (2007)

During the past decade, there has been a notable worldwide increase in the number of computed tomographic (CT) examinations. Since the radiation exposure to the patient during CT examinations is relatively high, it is important to optimize the dose so that it is set as low as possible but remains consistent with the required diagnostic image quality. Therefore we have developed a Digital Imaging and Communications in Medicine (DICOM) image-based program that calculates organ dose and effective dose values corresponding to tube current modulation. The values for primary radiation were derived from manufacturer specifications with international recommendations and from reference values (ICRP publication 60). Based on these values, organ doses can be computed by the program for arbitrary scan protocols in conventional and in spiral CT. In contrast to similar programs for CT dose assessment, our developed program can perform automatic extraction of the scan protocols from the DICOM tag. Users can easily reproduce and recalculate values by loading DICOM data without the requirement for time-consuming work. Additionally, further extensions are planned to our developed software.
The online Prize-Collecting Traveling Salesman Problem
Authors: Giorgio Ausiello, Vincenzo Bonifaci, Luigi Laura
Venue: Information Processing Letters (2008)

We study the online version of the Prize-Collecting Traveling Salesman Problem (PCTSP), a generalization of the Traveling Salesman Problem (TSP). In the TSP, the salesman has to visit a set of cities while minimizing the length of the overall tour. In the PCTSP, each city has a given weight and penalty, and the goal is to collect a given quota of the weights of the cities while minimizing the length of the tour plus the penalties of the cities not in the tour. In the online version, cities are disclosed over time. We give a 7/3-competitive algorithm for the problem, which compares with a lower bound of 2 on the competitive ratio of any deterministic algorithm. We also show how our approach can be combined with an approximation algorithm in order to obtain an O(1)-competitive algorithm that runs in polynomial time.
A Comprehensive Approach for Context-dependent Privacy Management
Authors: Elke Franz, Christin Groba, Thomas Springer, Mike Bergmann
Venue: Proceedings of the 2008 Third International Conference on Availability, Reliability and Security (2008)

Disclosing personal and contextual information enables a widespread use of services in the internet in a comfortable working environment adapted to individual user needs and preferences. On the other hand, information disclosure raises serious privacy issues. In this paper, we propose a novel integrated approach for achieving a good balance between convenience and privacy. We integrate Privacy-Enhancing Identity Management (PIM) with extended role-based access control mechanisms (RBAC) in an extended concept and architecture. In combination, both mechanism enable a fine grained control of what private and contextual information is disclosed to whom in what situation. We have implemented a Privacy-Enhanced Adaptive Communicator application (PEAC) to validate our approach.
Approximation through multicommodity flow
Authors: P. Klein, A. Agrawal, R. Ravi
Venue: Proceedings of the 31st Annual Symposium on Foundations of Computer Science (1990)

The first approximate max-flow-min-cut theorem for general multicommodity flow is proved. It is used to obtain approximation algorithms for minimum deletion of clauses of a 2-CNF identical to formula, via minimization problems, and other problems. Also presented are approximation algorithms for chordalization of a graph and for register sufficiency that are based on undirected and directed node separators.
Enhancing text clustering by leveraging Wikipedia semantics
Authors: Jian Hu, Lujun Fang, Yang Cao, Hua-Jun Zeng, Hua Li, Qiang Yang, Zheng Chen
Venue: Proceedings of the 31st annual international ACM SIGIR conference on Research and development in information retrieval (2008)

Most traditional text clustering methods are based on "bag of words" (BOW) representation based on frequency statistics in a set of documents. BOW, however, ignores the important information on the semantic relationships between key terms. To overcome this problem, several methods have been proposed to enrich text representation with external resource in the past, such as WordNet. However, many of these approaches suffer from some limitations: 1) WordNet has limited coverage and has a lack of effective word-sense disambiguation ability; 2) Most of the text representation enrichment strategies, which append or replace document terms with their hypernym and synonym, are overly simple. In this paper, to overcome these deficiencies, we first propose a way to build a concept thesaurus based on the semantic relations (synonym, hypernym, and associative relation) extracted from Wikipedia. Then, we develop a unified framework to leverage these semantic relations in order to enhance traditional content similarity measure for text clustering. The experimental results on Reuters and OHSUMED datasets show that with the help of Wikipedia thesaurus, the clustering performance of our method is improved as compared to previous methods. In addition, with the optimized weights for hypernym, synonym, and associative concepts that are tuned with the help of a few labeled data users provided, the clustering performance can be further improved.
Web knowledge extraction for improving search
Authors: Katsumi Tanaka
Venue: Proceedings of the 2nd international conference on Ubiquitous information management and communication (2008)

In this paper, we describe the extraction of Web knowledge from Web search engines and their usage for improving conventional Web search, such as supporting user's recall of vocabulary (query keywords), evaluation (quality, trustworthiness etc.) of search results, and re-ranking of search results. The extraction is based on the ideas of the "structural term co-occurrence" relationships and aggregating social annotation information, which can be easily computed by conventional Web search engines. Also, we describe a database interface to extract knowledge from Web search engines, which wraps accesses to Web search engines as virtual relational tables.