ppxscal/embedding_network huggingface dataset:
Projection method III: spatial discretization on the staggered grid
Authors: E. Weinan, Jian-Guo Liu
Venue: Mathematics of Computation (2002)

In E & Liu (SIAM J Numer. Anal., 1995), we studied convergence and the structure of the error for several projection methods when the spatial variable was kept continuous (we call this the semi-discrete case). In this paper, we address similar questions for the fully discrete case when the spatial variables are discretized using a staggered grid. We prove that the numerical solution in velocity has full accuracy up to the boundary, despite the fact that there are numerical boundary layers present in the semi-discrete solutions.
A load curve based fuzzy modeling technique for short-term load forecasting
Authors: S. E. Papadakis, J. B. Theocharis, A. G. Bakirtzis
Venue: Fuzzy Sets and Systems (2003)

A modeling method is suggested in this paper that permits building fuzzy models for short-term load forecasting (STLF). The model building process is divided in three parts: (a) the structure identification based on a fuzzy C-regression method, (b) selection of the proper model inputs which is achieved using a genetic algorithm based selection mechanism, and (c) fine tuning by means of a hybrid genetic/least squares algorithm. To obtain simple and efficient models we employ two descriptions for the load curves (LC's), namely, the feature description for the premise part and the cubic B-spline curve for the consequent part of the rules. The simulation results demonstrate that the suggested model exhibits very good forecast capabilities. The suggested model is favorably compared with the ANN model in terms of prediction accuracy, robustness and model complexity.
Fuzzy Variable Structure Control of a Class of Nonlinear Sampled-Data Systems
Authors: Mehmet Önder Efe
Venue: Journal of Dynamical and Control Systems (2003)

A novel approach to the fuzzy variable structure control is presented. The method is applicable to a class of discrete-time multi-input, multi-output systems. The controller for each subsystem is a two-input single-output fuzzy inference system partitioning the input space. The scheme presented analytically demonstrates that an appropriate tuning of the defuzzifier parameters can drive the plant to the desired sliding regime. The analysis begins with the extraction of the equivalent measure of the applied control signal, and continues with the proof of convergence claims for the discrete time sliding mode control. The method discussed has been applied to a double pendulum system, whose dynamics is assumed to be unknown, and the mathematical claims of the paper have been justified through a series of simulations. The results observed strongly recommend the use of the algorithm in the cases where the tracking precision and robustness against disturbances are sought.
A perspective on how ATM lost control
Authors: Simon Crosby, Sean Rooney, Rebecca Isaacs, Herbert Bos
Venue: ACM SIGCOMM Computer Communication Review (2002)

Contrary to the initial high expectations, ATM failed to become the universal network technology covering all services and running from the desktop to the backbone. This paper tries to identify the technological problems that contributed to this failure.
Diversity and the information technology workforce: an examination of student perceptions
Authors: A. Woszczynski, C. Beise, M. Myers, J. Moody
Venue: Proceedings of the 2003 SIGMIS conference on Computer personnel research: Freedom in Philadelphia--leveraging differences and diversity in the IT workforce (2003)

Most IT professionals would agree that diversity in IT leads to positive outcomes. However, few studies have empirically tested differences in diversity perceptions among groups. This research-in-progress develops a survey to test perceptions in four diversity categories: gender, ethnicity, age, and disability. Currently, we have begun collecting data from students in three universities. Upon completion of data collection, we plan to validate the survey instrument using factor analysis. Then we will test a series of directional hypotheses theorizing differences in diversity perceptions among groups. We will use multivariate analysis of variance (MANOVA) to analyze group differences and possible interaction effects. Upon completion of the study, we anticipate empirically validating a survey instrument to be used in future diversity studies, while also providing support for differences in diversity perceptions between the groups analyzed.
Relationality in Organizational Research: Exploring The Space Between
Authors: Hilary Bradbury, Benyamin M. Bergmann Lichtenstein
Venue: Organization Science (2000)

Relationships and interactions should be an important focus of attention in organizational scholarship. In contrast to traditional research approaches that focus on independent, discrete entities, methodologies oriented torelational concerns in organizations allow researchers to study the intersubjective and interdependent nature of organizational life. In addition to providing historical and philosophical bases for a perspective which emphasizes relationality, we review the growing number of methods that capture relational aspects of organizational life. Examples include network analysis, and "complexity" modeling, correspondence analysis and participatory research, case study methods, the learning history approach, psychometrics, and action inquiry. Our goal is to establish a "palette" of methodological choices for the researcher interested in operationalizing a relational perspective within organizational research/practice.
Modeling for environmental impacts using experimental data
Authors: S. M. Pandit, J. W. Sutherland, G. A. Bekkala
Venue: Development and application of computer techniques to environmental studies (2002)

Existing methods that assess the environmental impact often mandate an in depth understanding of the process or product mechanics. To overcome the complexity, the approach presented in this paper extracts the environmental impacts of a bench-top apparatus using Data Dependent Systems (DDS) methodology. The focus is on experimental evaluation of the environmental impacts of a bench-top heat exchanger system which simulates an industrial drying process. Collected measurements are used to develop DDS models from which an environmental profile is established for the heat exchanger. Results from the heat exchanger study provide insight into how the environmental impact of the industrial drying process may be reduced. Statistical design of experiments determines the significance of design variables. The process is quantified using characteristic roots of the DDS models providing natural frequencies and damping ratios, and these are subsequently associated with the environmental performance. Typical examples of DDS models are presented and their association with the environmental impact is demonstrated.
A Class of Label-Correcting Methods for the K Shortest Paths Problem
Authors: Francesca Guerriero, Roberto Musmanno, Valerio Lacagnina, Antonio Pecorella
Venue: Operations Research (2001)

In this paper we deal with the problem of finding the firstK shortest paths from a single origin node to all other nodes of a directed graph. In particular, we define the necessary and sufficient conditions for a set of distance label vectors, on the basis of which we propose a class of methods which can be viewed as an extension of the generic label-correcting method for solving the classical single-origin all-destinations shortest path problem. The data structure used is characterized by a set ofK lists of candidate nodes, and the proposed methods differ in the strategy used to select the node to be extracted at each iteration. The computational results show that: 1. some label-correcting methods are generally much faster than the double sweep method of Shier (1979); 2. the most efficient node selection strategies, used for solving the classical single-origin all-destinations shortest path problem, have proved to be effective also in the case of theK shortest paths.
Massive arrays of idle disks for storage archives
Authors: Dennis Colarelli, Dirk Grunwald
Venue: Proceedings of the 2002 ACM/IEEE conference on Supercomputing (2002)

The declining costs of commodity disk drives is rapidly changing the economics of deploying large amounts of online or near-line storage. Conventional mass storage systems use either high performance RAID clusters, automated tape libraries or a combination of tape and disk. In this paper, we analyze an alternative design using massive arrays of idle disks, or MAID. We argue that this storage organization provides storage densities matching or exceeding those of tape libraries with performance similar to disk arrays. Moreover, we show that with effective power management of individual drives, this performance can be achieved using a very small power budget. In particular, we show that our power management strategy can result in the performance comparable to an always-on RAID system while using 1/15th the power of such a RAID system.
Forecasting transformed series
Authors: C. W. J. Granger, P. Newbold
Venue: Essays in econometrics: Spectral analysis, seasonality, nonlinearity, methodology, and forecasting (2001)

Suppose that a forecasting model is available for the process Xt but that interest centres on the instantaneous transformation Yt = T(Xt). On the assumption that Xt is Gaussian and stationary, or can be reduced to stationarity by differencing, this paper examines the autocovariance structure of and methods for forecasting the transformed series. The development employs the Hermite polynomial expansion, thus allowing results to be derived for a very general class of instantaneous transformations.
SEOF: An Adaptable Object Prefetch Policy for Object-Oriented Database Systems
Authors: Jung-Ho Ahn, Hyoung-Joo Kim
Venue: Proceedings of the Thirteenth International Conference on Data Engineering (1997)

The performance of object access can be drastically improved by efficient object prefetch. In this paper we present a new object prefetch policy, Selective Eager Object Fetch(SEOF) which prefetches objects only from selected candidate pages without using any high level object semantics. Our policy considers both the correlations and the frequencies of fetching objects. Unlike existing prefetch policies, this policy utilizes the memory and the swap space of clients efficiently without resource exhaustion. Furthermore, the proposed policy has good adaptability to both the effectiveness of clustering and database size. We show the performance of the proposed policy through experiments over various multi-client system configurations.
Intelligent support framework of group decision making for complex business systems
Authors: Charu Chandra, Alexander V. Smirnov
Venue: Decision making support systems: achievements, trends and challenges for (2002)

As firms compete in global markets, they design and implement complex business systems, such as Supply Chain, Virtual Enterprise, Web-Based Enterprise, Production Network, e-Business, and e-Manufacturing. Common traits of these systems are (i) co-operation to implement shared goals, (ii) global distributed product development and manufacturing, and (iii) co-ordination of strategies and communication of information, among enterprise partners.Information in this complex business system can be shared via the Internet, Intranet, and Extranet. One of the goals of Internet-Based Management (e-management) is to facilitate transfer and sharing of data and knowledge in the context of business collaborations. It offers the platform for design and modeling of diverse implementation strategies related to the type of agreement, optimisation criteria, decision mode, organisation structures, information sharing mechanisms, and business policies for this system."A General Framework of E-Management" that integrates (i) intelligent information support, (ii) group-decision making, and (iii) agreement modeling for a complex business system is proposed. A generic methodology, of e-management information support based on "Ontology-Driven Knowledge Management" and "Multi and Intelligent Agents Technologies" for distributed decision making in scalable business systems is described. It is based on the premise that knowledge management should emphasize synergistic use of knowledge from multiple sources.
"Of course it's true; I saw it on the Internet!": critical thinking in the Internet era
Authors: Leah Graham, Panagiotis Takis Metaxas
Venue: Communications of the ACM (2003)

Students use the Net as a primary source of information, usually with little or no regard as to the accuracy of that information.
The Preferential Bidding System at Air Canada
Authors: Michel Gamache, Francois Soumis, Daniel Villeneuve, Jacques Desrosiers, Eric Gelinas
Venue: Transportation Science (1998)

This paper describes the Preferential Bidding Problem solved in the airline industry to construct personalized monthly schedules for pilots and officers. This problem consists in assigning to crew members pairings, days off, annual leaves, training periods, etc., while considering a set of weighted bids that reflect individual preferences. This assignment must be done under strict seniority restrictions: the construction of a maximum-score schedule for a particular crew member must never be done at the expense of a more senior employee. This research and development project has resulted in the Preferential Bidding System that has been used at Air Canada since May 1995. The solution process is summarized as follows. For each employee, from the most senior to the most junior, a so-called residual problem is solved: given an employee and a set of unassigned pairings, the solution to an integer linear program determines the employee's maximum-score schedule while taking into account all the remaining employees. The residual problem is solved by column generation embedded in a branch-and-bound tree. Integer solutions are obtained by using very efficient cutting planes, without which it would have been impossible to solve some of these residual problems.
The algorithms course: teaching recent advances in the state of the art
Authors: W. Douglas Maurer
Venue: Journal of Computing Sciences in Colleges (2002)

Many proofs of properties of algorithms may be simplified by the use of the method of indicator random variables. In addition, the relative speed of competing algorithms for the minimum-spanning-tree prob-lem, and also for the problem of finding shortest paths in a graph, is affected by the development of a data structure called the Fibonacci heap. These are just the most important of the recent advances in the state of the art of analyzing algorithms which, in our opinion, need to be taught as part of the algorithms course. We provide here a large number of updated methods which we have recently used in returning to teaching this course after a hiatus of many years.
Investigating open source software and educational robotics
Authors: Keith J. O'Hara, Jennifer S. Kay
Venue: Journal of Computing Sciences in Colleges (2003)

We investigate the role of open source software in the learning, teaching, utilization, and development of educational robotics and its corresponding core technologies. First, we present a survey of current open source solutions for the LEGO® MindStormsTM Robotics Invention SystemTM. Next, we discuss the role of open source software in the development of two undergraduate robotics projects.
Matrix Sensitivity Analysis From An Interior Solution of a Linear Program
Authors: Harvey J. Greenberg
Venue: INFORMS Journal on Computing (1999)

This article considers the effect of changing matrix coefficients in a linear program after we have obtained an interior solution. Changes are restricted to where there remains an optimal solution to the perturbed problem (called "admissible"). Mills' minimax theorem provides one approach and has been used for similar sensitivity analysis from a basic optimum. Here we consider the effect on the optimal partition and how the analysis results relate to the classical approach that uses a basic solution.
A Dialogue Process for Choosing Value-Creating Strategies
Authors: Samuel E. Bodily, Michael S. Allen
Venue: Interfaces (1999)

A decision process has proven effective in three activities thatare key to value creation: choosing an excellent strategy, actually bringing about change, and operating effectively with the new strategy. The dialogue is between a decision board and the strategy team as they work through six steps of a decision process. This process is focused on alternatives and implementation and is founded in decision analysis. Strategy frame-works and structuring tools are key to assessing the business situation. Risk and value trade-offs are made explicit, leading to concrete proposals to add value and reduce risk. Explicit plans for action are developed as the strategic alternative is chosen. Companies have developed strategy insights using this process, as we illustrate with examples from the pharmaceutical industry.
On the attractivity of a class of homogeneous dynamic economic systems
Authors: Weiye Li, Marek Rychlik, Ferenc Szidarovszky, Carl Chiarella
Venue: Nonlinear Analysis: Theory, Methods Applications (2003)

The attractivity properties of the set of equilibria of a special class of homogeneous dynamic economic systems are examined. The nonlinearity of the models and the presence of eigenvalues with zero real parts make the application of the classical theory impossible. Some principles of the modern theory of dynamical systems and invariant manifolds are applied, and the local attractivity of the set of equilibria is verified under mild conditions. As an application, special labor-managed oligopolies are investigated.
The Poisson equation for image texture modelling
Authors: Huawu Deng, Kap Luk Chan, Jun Liu
Venue: Pattern Recognition Letters (2003)

The Poisson equation is a class of partial differential equations which describe a steady-state temperature distribution in a bounded object. This paper applies this equation to the modelling of image textures by constructing specific heat source functions and boundary conditions. The heat source function can be considered as an image transform function such that a set of texture features at different frequencies and orientations can be extracted from the transformed image, in conjunction with using a Gabor wavelet filer bank. Better performance of image texture retrieval by these features is achieved than using the features extracted directly from the original image texture.
OPC-SMS: a wireless gateway to OPC-based data sources
Authors: Vassilis Kapsalis, Stavros Koubias, George Papadopoulos
Venue: Computer Standards Interfaces (2002)

This paper describes OPC-SMS gateway, a platform that integrates IP networks with the Short Message Service (SMS), in order to deliver an integrated service for access to data sources conforming to Object Linking and Embedding for Process Control (OPC) standard specifications, through SMS-enabled mobile devices. The gateway supports pull and push services in order to support both request-based and alarm/scheduled-based notifications, respectively. The proposed architecture is based entirely on the ubiquitous HyperText Transport Protocol (HTTP), Simple Object Access Protocol (SOAP), Extensible Markup Language (XML) protocols, and the Global System for Mobile communication (GSM) network and thus exploits the network infrastructure already in place. The capability of accessing different types of OPC data sources (real-time and historical) by any SMS-enabled device consists of a highly flexible service, supporting mobility and event-based notification. A pilot implementation of our approach has been tested in a large-scale installation for accessing OPC data sources of several automation subsystems in a hospital.
A Stochastic Modeling Approach to Real-Time Prediction of Queue Overflows
Authors: Jiuh-Biing Sheu
Venue: Transportation Science (2003)

Queue overflow is a critical issue in developing queue prediction technologies for applications in Advanced Transportation Management System (ATMS). Conventional queue prediction methods, however, are limited to incident-free queue length prediction where traffic arrivals can be readily obtained using detectors. Despite the problems posed by queue overflow, studies addressing queue-overflow issues, or for predicting queue overflows beyond detectors, appear inadequate. This paper describes an advanced methodology which uses a stochastic system modeling approach and random processes for predicting queue lengths beyond detectors in real time. Lane changing is taken into account in developing the queue-overflow prediction model because lane changing accompanies queue overflow in most cases. A discrete-time, nonlinear stochastic system is specified for modeling the queues and lane changes beyond detectors during queue-overflow occurrence. The noise terms of the recursive equations of the model account for the effects of queues and a variety of arriving volumes on vehicular lane-changing maneuvers during queue-overflow occurrence. The unknown traffic arrivals beyond detectors are predicted employing random processes. In addition, a recursive estimation algorithm for predicting real-time queue overflows is developed utilizing the extended Kalman filtering technique. Preliminary test results indicate that the proposed methodology is promising for real-time prediction of queue overflows. The predicted queue overflows can be used not only in understanding the phenomenon of lane traffic patterns during queue-overflow occurrence, but also in developing related advanced technologies such as real-time road traffic congestion control and management systems.
An Efficient Algorithm for Solving An Air Traffic Management Model of the National Airspace System
Authors: E. Andrew Boyd, Rusty Burlingame, Kenneth Lindsay
Venue: INFORMS Journal on Computing (1998)

Growth in traffic and changes in traffic patterns have caused an increase in the congestion and delay in the National Airspace System. Air traffic delay is very costly to the airlines, and minimizing this delay has been a subject of research for over a decade. A large integer programming model developed at the MITRE Corporation for minimizing air traffic delay is presented. Solving problem instances arising from this model involves the use of preprocessing, constraint strengthening, and a carefully designed computer implementation. Results are presented, demonstrating that the model can be solved to provable optimality in real time for problem instances involving over 1 million binary variables.
A Hybrid Exact Algorithm for the TSPTW
Authors: Filippo Focacci, Andrea Lodi, Michela Milano
Venue: INFORMS Journal on Computing (2002)

TheTraveling Salesman Problem with Time Windows (TSPTW) is the problem of finding a minimum-cost path visiting a set of cities exactly once, where each city must be visited within a specific time window. We propose a hybrid approach for solving the TSPTW that merges Constraint Programming propagation algorithms for the feasibility viewpoint (find a path), and Operations Research techniques for coping with the optimization perspective (find the best path). We show with extensive computational results that the synergy between Operations Research optimization techniques embedded in global constraints, and Constraint Programming constraint solving techniques, makes the resulting framework effective in the TSPTW context also if these results are compared with state-of-the-art algorithms from the literature.