ppxscal/embedding_network huggingface dataset:
Load Unbalancing to Improve Performance under Autocorrelated Traffic
Authors: Qi Zhang, Ningfang Mi, Alma Riska, Evgenia Smirni
Venue: Proceedings of the 26th IEEE International Conference on Distributed Computing Systems (2006)

Size-based policies have been shown to successfully balance load and improve performance in homogeneous cluster environments where a dispatcher assigns a job to a server strictly based on the job size. While the success of size-based policies is based on separating jobs to different servers according to their sizes by avoiding the unfavorable performance effects of having short jobs been stuck behind long jobs, we show that their effectiveness quickly deteriorates in the presence of job arrivals that are characterized by correlation in their dependence structure. We propose a new policy that still strives to separate jobs according to their sizes, but this separation is biased by the effort to reduce the performance loss due to autocorrelation. As a result, not all servers are equally utilized (i.e., the load in the system becomes unbalanced) but the performance benefits of this load unbalancing are significant. The proposed policy can be used on-line, i.e., it does not assume any knowledge neither of the correlation structure of the arrival stream, nor of the job size distribution in the system. Via detailed trace-driven simulation we quantify the performance benefits of the proposed policy and we show that it can effectively self adjust its configuration parameters to improve performance under continuously changing workload conditions.
Scaffolding learning from contrasting video cases
Authors: Anandi Nagarajan, Cindy Hmelo-Silver
Venue: Proceedings of the 7th international conference on Learning sciences (2006)

Video cases can serve as valuable instructional tools for preservice teachers by presenting examples of effective and ineffective student learning and pedagogical approaches. However, merely seeing video-cases without in-depth, interpretive analysis may not ensure learning. This study examined the effects of cognitive, metacognitive, combination, and affective questions, on preservice teachers' declarative knowledge of formative assessment, case-interpretation skills and ability to redesign formative assessments in similar and novel classroom contexts. All participants showed significant improvements from pretest to posttest on declarative knowledge and case-interpretation skills. A-priori planned contrasts revealed that the cognitive-questions group outperformed the metacognitive group on declarative knowledge whereas the metacognitive-questions group outperformed the cognitive group on video case-interpretation at posttest and transfer tasks. The results suggest practical implications for using specific scaffolding questions that are effective in improving conceptual knowledge and applied case-interpretation skills during contrasting video case analysis activities.
Loss ratio approximations in buffered systems with regulated inputs
Authors: József Bíró
Venue: Proceedings of the 1st international conference on Performance evaluation methodolgies and tools (2006)

The estimation of the expected traffic loss ratio (workload loss ratio, WLR) is a key issue in provisioning Quality of Service in packet based communication networks. The stationary (long run) loss ratio in queuing analysis is usually estimated through other assessable quantities, typically based on the approximates of the buffer overflow probability. These approaches have the drawback, that the relation between loss ratio and buffer overflow probability is often hardly quantifiable and it can in principle be arbitrary. In this paper we present novel upper approximations for workload loss ratio derived from the original definition of stationary loss ratio. These direct bounds are applicable for general service curve network elements with regulated flows acting as inputs. The performance of these bounds is systematically analyzed and compared to prior indirect (based on buffer saturation probability) loss ratio bound and its newly developed improvements. The extensive numerical investigations also exemplify that in most cases our novel direct bounds can lead to significant save in buffer requirements when guaranteeing a prescribed QoS level in terms of loss ratio.
A co-phase matrix to guide simultaneous multithreading simulation
Authors: M. Van Biesbrouck, T. Sherwood, B. Calder
Venue: Proceedings of the 2004 IEEE International Symposium on Performance Analysis of Systems and Software (2004)

Several commercial processors have architectures that include support for simultaneous multithreading (SMT), yet there is still not a validated methodology for estimating the performance of an SMT machine that does not rely on full program simulation. To create an efficient sampling approach for SMT we must determine how far to fast-forward each individual thread between samples. The fast-forwarding distance for each thread will vary according to execution phases, thread interactions and changes to the architectural configuration. We examine using individual program phase information to guide SMT simulation. This is accomplished by creating what we call a co-phase matrix. The co-phase matrix is populated by collecting samples of the programs' phase combinations, and is used to guide fastforwarding between samples. We show for 28 pairs of SPEC programs that using the co-phase matrix provides an average error rate of 4% while requiring that only 1% of the full simulation be performed. The methods are also validated using a variety of architectural configurations and four-threaded workloads.
Approximate closed-form aggregation of a fork-join structure in generalised stochastic petri nets
Authors: Nimrod Lilith, Jonathan Billington, Jörn Freiheit
Venue: Proceedings of the 1st international conference on Performance evaluation methodolgies and tools (2006)

In this paper an aggregation technique for generalised stochastic Petri nets (GSPNs) possessing synchronised parallel structures is presented. Parallel processes featuring synchronisation constraints commonly occur in fields such as product assembly and computer process communications, however their existence in closed networks severely complicates analysis. This paper details the derivation of computationally-simple closed-form expressions which permit the aggregation of a GSPN subnet featuring a fork-join structure. The aggregation expressions presented in this paper do not require the generation of the underlying continuous time Markov chain of the original net, and do not follow an iterative procedure. The resulting aggregated GSPN accurately approximates the stationary token distribution behaviour of the original net, and this is shown by the analysis of a number of example GSPNs.
A fast algorithm for convolution integrals with space and time variant kernels
Authors: Erez Gilad, Jost von Hardenberg
Venue: Journal of Computational Physics (2006)

Mathematical models in many fields of the physical sciences involve nonlocal terms which are formally similar to convolution integrals. We show that it is possible to approximate a particular class of such integrals, which by themselves are not convolutions, as a linear combination of convolution integrals, allowing for their efficient numerical computation as an O(N log N) process.
A New Initialization Method for Constructing Centroidal Voronoi Tessellations on Surface Meshes
Authors: Masaki Moriguchi, Kokichi Sugihara
Venue: Proceedings of the 3rd International Symposium on Voronoi Diagrams in Science and Engineering (2006)

Centroidal Voronoi tessellations can be constructed using iterative improvement methods such as Lloyd's method. Using iterative improvement methods implies that the convergence speed and the quality of the results depend on the initialization methods. In this paper, we propose an efficient initialization method for constructing centroidal Voronoi tessellations on surface meshes. The proposed method tries to make initial tessellations mimic the properties of the centroidal Voronoi tessellations. We compare our method with other initialization methods: random sampling, farthest point sampling and Ward's method. The results show that our method and Ward's method have the faster convergence speed than random sampling and farthest point sampling, and create better tessellations than random sampling.
Collaborative Logistics: Developing a Framework to Evaluate Socio-Technical Issues in Logistic-Based Networks
Authors: Joseph Lyons, Jill Ritter, Krystal Thomas, Laura Militello, Patrick Vincent
Venue: Proceedings of the International Symposium on Collaborative Technologies and Systems (2006)

The concepts of collaborative logistics, logisticsbased networks, focused logistics, and distributed adaptive logistics describe a futuristic approach to logistics planning encompassing automated, adaptive technologies, and proactive human collaboration. Such an approach creates novel challenges for collaboration within socio-technical systems, which encompass the collaborative technologies, the people and machines involved in the act of collaboration, and social context of collaboration. These challenges need to be addressed by theoretical models incorporating multidisciplinary approaches to the study of collaboration. The present paper introduces a framework for collaboration which may inform the design and implementation of collaborative technologies and systems from a socio-technical perspective.
Research on Remote Heterogeneous Disaster Recovery Technology in Grid Computing Security
Authors: Ronghui Wu, Renfa Li, Fei Yu, Guangxue Yue, Jigang Wen
Venue: Proceedings of the Second International Conference on Semantics, Knowledge, and Grid (2006)

The tradition standby mechanism can't carry out the dynamic Disaster Recovery of database between distributed isomeric storage systems, accordingly, research the method of allopatric isomeric backup based on grid calculation is an important research subject. In this paper, some technique and strategy of allopatric isomeric backup in grid calculation environment are researched by comparing and analyzing the existing technique of database allopatric backup, a remote-data copy method is presented, a remote-data disaster dump system and a allopatric isomeric data Disaster Recovery tool are designed and implemented based on interlayer.
Optimal receiver design with wavelet bases
Authors: N. Erdol, Feng Bao, F. Basbug
Venue: Proceedings of the Acoustics, Speech, and Signal Processing,1994. on IEEE International Conference - Volume 04 (1994)

A generalized orthogonal series expansion should reflect the natural modes of a signal. In doing so, the transform becomes precise and useful. The most precise transform is the Karhunen-Loeve (KL) transform. The covariance function of a signal expanded in its KL basis has uncorrelated coefficients. This property can be used to derive optimal detection structures. Erdol and Bao (see Proceedings of the Asilomar Conf. on Signals, Systems and Computers, 1993) addressed the classical problem of detection of a message signal in white noise by considering a variable coefficient wavelet series expansion of the input signal. It is shown that, given the hypothesis that there exists a wavelet eigen basis of the message signal, then the optimization problem of searching for the eigen wavelet may be transformed into a search over an array of variables. These variables are shown to be the coefficients that arise in the representation of one wavelet basis in terms of another. In this paper, the structure of this array of coefficients is explored for simplifying the search space.
Using Correlation to Improve Boosting Technique: An Application for Time Series Forecasting
Authors: Luzia Vidal de Souza, Aurora T. Ramirez Pozo, Anselmo Chaves Neto
Venue: Proceedings of the 18th IEEE International Conference on Tools with Artificial Intelligence (2006)

Time series forecasting has been widely used to support decision making, in this context a highly accurate prediction is essential to ensure the quality of the decisions. Ensembles of machines currently receive a lot of attention; they combine predictions from different forecasting methods as a procedure to improve the accuracy. This paper explores Genetic Programming and Boosting technique to obtain an ensemble of regressors and proposes a new formula for the final hypothesis. This new formula is based on the correlation coefficient instead of the geometric median used by the boosting algorithm. To validate this method, experiments were performed, the mean squared error (MSE) has been used to compare the accuracy of the proposed method against the results obtained by GP, GP using a Boosting technique and the traditional statistical methodology (ARMA). The results show advantages in the use of the proposed approach.
Numerical methods for the estimation of multifractal singularity spectra on sampled data: a comparative study
Authors: Antonio Turiel, Conrad J. Pérez-Vicente, Jacopo Grazzini
Venue: Journal of Computational Physics (2006)

Physical variables in scale invariant systems often show chaotic, turbulent-like behavior, commonly associated to the existence of an underlying fractal or multifractal structure. However, the assessment of multifractality over experimental, discretized data requires of appropriate methods and to establish criteria to measure the confidence degree on the estimates. In this paper we have evaluated the quality of different techniques used for multifractal analysis. We have tested four different techniques: the moment (M) method, the wavelet transform modulus maxima (WTMM) method, the gradient modulus wavelet projection (GMWP) method and the gradient histogram (GH) method, which are used to estimate the singularity spectra of multifractal signals. The test consists in analyzing synthetic multifractal 1D signals with given multifractal spectrum. We have compared the results, studying the sensibility of each method to the length of the series, size of the ensemble and type of spectrum. Our results show that GMWP method is the one attaining the best performance, providing reliable estimates which can be improved when the statistics is increased. All the other methods are affected by problems such as the linearization of the right tail of the spectrum, and some of them are very demanding in data.
In this work, we propose two translations: one from extended
Authors: Karine Altisen, Franck Cassez, Stavros Tripakis
Venue: Proceedings of the Sixth International Conference on Application of Concurrency to System Design (2006)

We study the monitoring and fault-diagnosis problems for dense-time real-time systems, where observers (monitors and diagnosers) have access to digital rather than analog clocks. Analog clocks are infinitely-precise, thus, not implementable. We show how, given a specification modeled as a timed automaton and a timed automaton model of the digital clock, a sound and optimal (i.e., as precise as possible) digital-clock monitor can be synthesized. We also show how, given plant and digital clock modeled as timed automata, we can check existence of a digital-clock diagnoser and, if one exists, how to synthesize it. Finally, we consider the problem of existence of digital-clock diagnosers where the digital clock is unknown. We show that there are cases where a digital clock, no matter how precise, does not exist, even though the system is diagnosable with analog clocks. Finally, we provide a sufficient condition for digital-clock diagnosability.
Computational balance in real-time cyclic spectral analysis
Authors: R. S. Roberts
Venue: Proceedings of the Acoustics, Speech, and Signal Processing,1994. on IEEE International Conference - Volume 04 (1994)

Real-time cyclic spectral analysis is useful in many applications, but is difficult to achieve because of its computational complexity. This paper studies the distribution of complex multipliers in multiprocessor cyclic spectrum analyzers, with the objective of obtaining computational balance. Computationally balanced implementations efficiently use hardware so that computational bottlenecks are reduced and a smooth flow of data between computational sections of the analyzer is maintained. Tables are presented that give the number of complex multipliers required in each section of the analyzer to obtain computational balance. 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
Taking Sensor Networks from the Lab to the Jungle
Authors: Andrew S. Tanenbaum, Chandana Gamage, Bruno Crispo
Venue: Computer (2006)

Researchers must address the systems aspects of wireless sensor networks.
Specifying Agent Support for Collaboration
Authors: Igor Hawryszkiewycz
Venue: Proceedings of the International Symposium on Collaborative Technologies and Systems (2006)

Adoption of leading edge collaborative technologies requires considerable facilitation. There are two options to provide such support. The most common is by special human coordination roles. Another is by software agents. The paper describes a method to provide facilitation using software agents. It emphasizes the need to develop reusable agents and proposes an ontology as a basis for discovering such reusable agents. It then describes a framework for developing agents with increasing collaborative capabilities and describes a prototype implementation.
Optimization of airport taxiways using fast time simulation
Authors: John Podlena, Keith Joshi
Venue: Proceedings of the 37th conference on Winter simulation (2005)

With an increasing demand for throughput experienced by many large airports, airport authorities are frequently looking at ground infrastructure changes to increase both airport capacity and safety while reducing delays. One such infrastructure change involves the building of new aircraft taxiways to alleviate existing or possible bottlenecks, or to open up new paths for taxiing aircraft to ground destinations such as runways and terminal gates. With a commonly limited budget for such infrastructure changes, simulation provides a vital tool for the investigation of the location of such taxiways on an airport layout and the resulting efficiency gains to be expected. This paper details a proposed system for the automated optimization of taxiway placement using a fast time simulator (the Total Airspace and Airport Modeler).
A multiscale V-P discretization for flow problems
Authors: Leo G. Rebholz
Venue: Applied Mathematics and Computation (2006)

This paper gives a comprehensive numerical analysis of a multiscale method for equilibrium Navier Stokes equations. The method includes pressure regularization and eddy viscosity stabilizations both acting only on the finest scales. This method allows for equal order velocity-pressure spaces as well as the linear constant pair and the usual (Pk, Pk-1) pair. We show the method is optimal in a natural energy norm for all of these pairs of spaces, and provide guidance in choosing the regularization parameters.
How Open is e-Science?
Authors: Paul A. David, Matthijs den Besten, Ralph Schroeder
Venue: Proceedings of the Second IEEE International Conference on e-Science and Grid Computing (2006)

This paper examines various aspects of "openness" in research, and seeks to gauge the degree to which escience is congruent with "open science." Norms and practices of openness, arguably, have been vital for the work of modern scientific communities, but concerns about the growth of stronger technical and institutional restraints on access to research tools, data and information recently have attracted increased notice -- in part because of their implications for the effective utilization of advanced digital infrastructures and information technologies in research collaborations. Our discussion clarifies the conceptual distinctions between e-science and open science, and reports findings from a preliminary look at practices in U.K. e-science projects. Both parts serve to underscore the point that it is unwarranted to presume that the development of e-science necessarily promotes global open science collaboration. A programme of further empirical studies is outlined, aimed at establishing where, when, and to what extent "openness" and" eness" in scientific and engineering research may be expected to advance hand-in-hand.
Global bifurcations and chaos in polynomial dynamical systems
Authors: V. A. Gaiko
Venue: Proceedings of the 2003 International Conference on Physics and Control - Volume 2 (2003)

Polynomial dynamical systems are considered. First of all, we study global bifurcations of multiple limit cycles in two-dimensional systems developing a new approach to Hilbert's Sixteenth Problem on the maximum number and relative position of limit cycles. The problem has not been solved completely even for the simplest nonlinear case: for the case of quadratic systems, and we suggest a program solving this problem in the quadratic case. This approach can be applied also to the study of arbitrary polynomial systems and to the global qualitative analysis of higher-dimensional dynamical systems. In particular, we discuss how to apply the obtained results for the construction of a three-dimensional system with a "strange attractor" on the base of a planar quadratic system with two unstable foci and an invariant straight line. This study could give us a chaos birth bifurcation in the polynomial dynamical systems. 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
A neuroimaging pilot study of task loading and executive function using a virtual apartment
Authors: Stephen Baumann
Venue: Presence: Teleoperators and Virtual Environments (2005)

Frontal-lobe injuries often adversely affect cognitive functions such as planning and decision making. These are known as executive functions, and they reside largely in the frontal lobes of the brain. In preparation for studies of patients with cognitive deficits, including a large study of Vietnam veterans with frontal-lobe injuries, 3 normal subjects participated in a functional magnetic resonance imaging (FMRI) pilot study of cognitive function while using an interactive virtual apartment constructed with computer-game development software. At least 1 day prior to the FMRI scan, subjects were given a passive tour of multiple environments within a virtual world and then allowed to practice navigating through the world using a joystick and touch pad. Within a week they returned for the FMRI study, in which they were given 2 minutes on each of 5-7 contiguous runs to perform tasks within the virtual apartment that were designed to be increasingly difficult (i.e., task loading). For example, in one of the least difficult runs, they were asked to navigate through a small apartment of 5 rooms and to turn on all of the light switches. In the last and potentially most difficult run, they were asked to find and open all of the closets (4) in the apartment and mentally categorize and count the number of items within the closets. After the data were detrended and filtered, the effects of task performance on brain-activation patterns were computed. There was a statistically significant correlation between subjective rating of task difficulty and pixel intensity in the anterior frontal lobes compatible with highly significant bilateral activation when the more difficult tasks were compared to the less difficult tasks. This study illustrates how virtual environments can be used for more naturalistic studies of executive function, and it provides normative data for later comparison with head-injured patients.