ppxscal/embedding_network huggingface dataset:
Research Commentary: Technology-Mediated Learning--A Call for Greater Depth and Breadth of Research
Authors: Maryam Alavi, Dorothy E. Leidner
Venue: Information Systems Research (2001)

Universities and corporate training facilities have been investing in information technologies to improve education and training at an increasing rate during the past decade. Many new companies are emerging to provide tools and services to enable the effective design of IT-based learning solutions. Although research on technology-mediated learning has increased in recent years, it still lags behind developments in practice. This essay suggests potential research avenues in the area of technology-mediated learning. It seeks to motivate greater depth of research into the question of how technology enhances learning. This question requires an explicit consideration of relationships among technology capabilities, instructional strategy, psychological processes, and contextual factors involved in learning. The essay also recommends attention to a greater breadth of research questions, including issues of how technology-mediated learning affects program design and what structures and processes universities can employ to facilitate innovation.
Search space reduction in optical tracking
Authors: Robert van Liere, Arjen van Rhijn
Venue: Proceedings of the workshop on Virtual environments 2003 (2003)

In this paper we present a practical method for reducing the space when searching for point patterns in optically tracked virtual reality applications. The method uses a predictor to estimate the future position of a point. The key idea is to define a metric that determines the quality of the predictor, and use this metric to construct a 3D region around the predicted position of each point. The size and shape of the 3D region is based on the kinematic properties of the predicted point. The 3D region is projected into 2D to obtain the required search window.The contribution of the paper is that the search space can be reduced substantially by making use of adaptive window shapes and sizes.
Computation of few Lyapunov exponents by geodesic based algorithms
Authors: N. Del Buono, C. Elia
Venue: Future Generation Computer Systems (2003)

In this paper, we apply numerical methods based on the embedded geodesics for computing few Lyapunov exponents of a finite dimensional dynamical system. These new numerical algorithms are designed using geometric structure of the Stiefel manifold and they preserve orthogonality to machine accuracy. Numerical tests are also provided in order to show the features of our methods.
Strong tractability of multivariate integration using quasi-Monte Carlo algorithms
Authors: Xiaoqun Wang
Venue: Mathematics of Computation (2003)

We study quasi-Monte Carlo algorithms based on low discrepancy sequences for multivariate integration. We consider the problem of how the minimal number of function evaluations needed to reduce the worst-case error from its initial error by a factor of ε depends on ε-1 and the dimension s. Strong tractability means that it does not depend on s and is bounded by a polynomial in ε-1. The least possible value of the power of ε-1 is called the ε-exponent of strong tractability. Sloan and Wozniakowski established a necessary and sufficient condition of strong tractability in weighted Sobolev spaces, and showed that the ε-exponent of strong tractability is between 1 and 2. However, their proof is not constructive.In this paper we prove in a constructive way that multivariate integration in some weighted Sobolev spaces is strongly tractable with ε-exponent equal to 1, which is the best possible value under a stronger assumption than Sloan and Wozniakowski's assumption. We show that quasi-Monte Carlo algorithms using Niederreiter's (t, s)-sequences and Sobol sequences achieve the optimal convergence order O(N-1+δ) for any δ > 0 independent of the dimension with a worst case deterministic guarantee (where N is the number of function evaluations). This implies that strong tractability with the best ε-exponent can be achieved in appropriate weighted Sobolev spaces by using Niederreiter's (t,s)-sequences and Sobol sequences.
Core Problems in Knapsack Algorithms
Authors: David Pisinger
Venue: Operations Research (1999)

Since Balas and Zemel in the 1980s introduced the so-called core problem as an efficient tool for solving the Knapsack Problem, all the most successful algorithms have applied this concept. Balas and Zemel proved that if the weights in the core are uniformly distributed then there is a high probability for finding an optimal solution in the core. Items outside the core may be fathomed because of reduction rules. This paper demonstrates that generally it is not reasonable to assume a uniform distribution of the weights in the core, and it is experimentally shown that the heuristic proposed by Balas and Zemel does not find as good solutions as expected. Also, other algorithms that solve some kind of core problem may be stuck by difficult cores. This behavior has apparently not been noticed before because of unsufficient testing. Capacities leading to difficult problems are identified for several categories of instance types, and it is demonstrated that the hitherto applied test instances are easier than the average. As a consequence we propose a series of new randomly generated test instances and show how recent algorithms behave when applied to these problems.
An hybrid methodology for the modeling and the simulation of natural systems
Authors: Frederic Chiari, Marielle Delhom, Jean-François Santucci
Venue: Systems Analysis Modelling Simulation (2002)

In this paper, we first present concepts we developed in order to define an hybrid modeling and simulation methodology dedicated to the study of natural systems.These concepts are based on the object-oriented design, artificial neural networks and the geographic information systems. Then, we outline a general framework combining these three concepts.A first application allowing the forecasting of the hydrologic behavior of watersheds is described and some results are presented and commented.
Comparison theorem for hybrid fuzzy differential equations
Authors: Abdelkrim Brania, Negash G. Medhin, M. Sambandham
Venue: Second international workshop on Intelligent systems design and application (2002)

By applying the theory of fuzzy inequalities, we develop a useful comparison theorem for hybrid fuzzy differential equations.
Simple maintenance of Beowulf clusters in an academic environment
Authors: Chrisila Pettey, Ralph Butler, Brad Rudnick, Thomas Naughton
Venue: Journal of Computing Sciences in Colleges (2002)

We present our experiences with an evolving installation system for small- to medium-sized clusters which are typically used in academic settings to support a combination of teaching and research. All of the software developed by us for this system can be stored on a single floppy disk. This is due to the fact that we assume that the user already has an open-source operating system available on CD or other such media. In order to provide a reliable, cost-effective, accessible teaching/research environment, where students are given totally free rein, including root access, this system requires the ability to be rapidly restored.
Estimation and Prediction of Time-Dependent Origin-Destination Flows with a Stochastic Mapping to Path Flows and Link Flows
Authors: K. Ashok, M. E. Ben-Akiva
Venue: Transportation Science (2002)

This paper presents a new suite of models for the estimation and prediction of time-dependent Origin-Destination (O-D) matrices. The key contribution of the proposed approach is the explicit modeling and estimation of the dynamic mapping (theassignment matrix) between time-dependent O-D flows and link volumes. The assignment matrix depends upon underlying travel times and route choice fractions in the network. Since the travel times and route choice fractions are not known with certainty, the assignment matrix is prone to error. The proposed approach provides a systematic way of modeling this uncertainty to address both theoffline andreal-time versions of the O-D estimation/prediction problem. Preliminary empirical results indicate that generalized models with a stochastic assignment matrix could provide better results compared to conventional models with a fixed matrix.
The principles of using the equigradient and reflection lines as the tools of surface continuity diagnosis
Authors: Barbara Putz
Venue: Machine Graphics Vision International Journal (2002)

The paper presents new theorems about characteristic curves on the surface used as a shape smoothness diagnosis tool. First, general principles of examination of characteristic curves, treated as contour lines of a shape function, are presented. Two subsequent sections deal with properties of two most popular characteristic curves: equigradient lines and reflection lines. The theorems presented there are a theoretical background for evaluation of the surface continuity via of examination of these type of lines.
Automorphism Partitioning with Neural Networks
Authors: Brijnesh J. Jain, Fritz Wysotzki
Venue: Neural Processing Letters (2003)

We present a neural approach for approximating the automorphism partitioning problem of a given graph. This approach combines the energy minimization process of neural networks for combinatorial optimization problems with simple group-theoretic properties. Neural networks are applied to rapidly find relevant automorphisms while group-theoretic information guides the search for these automorphisms.
The Uncapacitated Facility Location Problem with Client Matching
Authors: Éric Gourdin, Martine Labbé, Gilbert Laporte
Venue: Operations Research (2000)

TheUncapacitated Facility Location Problem with Client Matching (LCM) is an extension of theUncapacitated Facility Location Problem (UFLP), where two clients allocated to a facility can be matched. As in the UFLP, facilities can be opened at any ofm predefined locations with given fixed costs, andn clients have to be allocated to the open facilities. In classical location models, the allocation cost is the distance between a client and an open facility. In the LCM, the allocation cost is either the cost of a return trip between the facility and the client, or the length of a tour containing the facility and two clients. The similarities of the LCM with the classical UFLP and the matching problem are exploited to derive valid inequalities, optimality cuts, and polyhedral results. A greedy heuristic and a branch-and-cut algorithm are developed, and several separation procedures are described. Computational experiments confirm the efficiency of the proposed approach.
Visualization of program-execution data for deployed software
Authors: Alessandro Orso, James Jones, Mary Jean Harrold
Venue: Proceedings of the 2003 ACM symposium on Software visualization (2003)

Software products are often released with missing functionality, errors, or incompatibilities that may result in failures in the field, inferior performances, or, more generally, user dissatisfaction. In previous work, we presented the GAMMA technology, which facilitates remote analysis and measurement of deployed software and allows for gathering programexecution data from the field. When monitoring a high number of deployed instances of a software product, however, a large amount of data is collected. Such raw data are useless in the absence of a suitable data-mining and visualization technique that supports exploration and understanding of the data. In this paper, we present a new technique for collecting, storing, and visualizing program-execution data gathered from deployed instances of a software product. We also present a prototype toolset, GAMMATELLA, that implements the technique. We show how the visualization capabilities of GAMMATELLA allows for effectively investigating several kinds of execution-related information in an interactive fashion.
Nonlinear Shape Normalization Methods for Gray-Scale Handwritten Character Recognition
Authors: Sang-Yup Kim, Seong-Whan Lee
Venue: Proceedings of the 4th International Conference on Document Analysis and Recognition (1997)

In this paper, we propose nonlinear shape normalization methods for gray-scale handwritten characters in order to minimize the loss of information caused by binarization and compensate for the shape distortions of characters. Two-dimensional linear interpolation technique has been extended to nonlinear space and the extended interpolation technique has been adopted in the proposed methods to enhance the quality of normalized images.In order to verify the efficiency of the proposed methods, the recognition rate, the processing time and the computational complexity of the proposed algorithms have been considered. The experimental results indicate that the proposed methods are efficient not only to compensate for the shape distortions of handwritten characters but also to maintain the information of gray-scale input characters.
Who Links to Whom: Mining Linkage between Web Sites
Authors: Krishna Bharat, Bay-Wei Chang, Monika Rauch Henzinger, Matthias Ruhl
Venue: Proceedings of the 2001 IEEE International Conference on Data Mining (2001)

Previous studies of the web graph structure have focused on the graph structure at the level of individual pages. In actuality the web is a hierarchically nested graph, with domains, hosts and web sites introducing intermediate levels of affiliation and administrativecontrol. To better understand the growth of the web we need to understand its macro-structure, in terms of the linkage between web sites. In this paper e approximate this by studying the graph of the linkage between hosts on the web. This as done based on snapshots of the web taken by Google in Oct 1999,Aug 2000 and Jun 2001.The connectivity between hosts is represented by a directed graph, with hosts as nodes and weighted edges representingthe count of hyperlinks between pages on the corresponding hosts. We demonstrate how such a "hostgraph" an be used to study connectivity properties of hosts and domains over time, anddiscuss a modified "copy model" too explain observed link eight distributions as a function of subgraph size. We discuss changes in the web over time in the size and connectivity of web sites and country domains. We also describe a data mining application of the hostgraph: a related host finding algorithm which achieves a precision of 0.65 at rank 3.
Internet path characterization using common internet tools
Authors: Dulal C. Kar
Venue: Journal of Computing Sciences in Colleges (2003)

Ping and traceroute are two popular Internet tools that allow network administrators and users to detect problems on the Internet. The most popular use of ping is to find out whether a host on a network is online or not. However, the most popular use of traceroute is to identify routers along an Internet path. Each tool has many other uses often ignored by common users. This work describes how to use these tools to find the bandwidth of an Internet link, discover the path MTU (Maximum Transmission Unit), identify the bottleneck link in a path, and detect and measure upstream and downstream bandwidths of an asymmetric link. By conducting such experiments, students in networking courses can obtain a good insight of an Internet path and be interested in in-depth research and further study in computer networking.
Experiences with predicting resource performance on-line in computational grid settings
Authors: Rich Wolski
Venue: ACM SIGMETRICS Performance Evaluation Review (2003)

In this paper, we describe methods for predicting the performance of Computational Grid resources (machines, networks, storage systems, etc.) using computationally inexpensive statistical techniques. The predictions generated in this manner are intended to support adaptive application scheduling in Grid settings, and on-line fault detection. Wedescribe a mixture-of-experts approach to non-parametric, univariate time-series forecasting, and detail the effectiveness of the approach using example data gathered from "production" (i.e. non-experimental) Computational Grid installations.
Enforcing behavior with contracts
Authors: Ralph-Johan Back, Joakim von Wright
Venue: Programming methodology (2003)

Contracts have been introduced earlier as a way of modeling a collection of agents that work within the limits set by the contract. We have analyzed the question of when an agent or a coalition of agents can reach a stated goal, despite potentially hostile behavior by the other agents. In this paper, we extend the model so that we can also study whether a coalition of agents can enforce a certain temporal behavior when executing a contract. We show how to reduce this question to the question of whether a given goal can be achieved. We introduce a generalization of the action system notation that allows both angelic and demonic scheduling of actions. This allows us to model concurrent systems and interactive systems in the same framework, and show that one can be seen as the dual of the other. We analyze enforcement of temporal behavior in the case of action systems, and show that these provide for simpler proof obligations than what we get in the general case. Finally, we give three illustrative examples of how to model and analyze interactive and concurrent systems with this approach.
A Decade of Hardware/Software Codesign
Authors: Wayne Wolf
Venue: Computer (2003)

The term hardware/software codesign, coined about 10 years ago, describes a confluence of problems in integrated circuit design. By the 1990s, it became clear that microprocessor-based systems would be an important design discipline for IC designers as well. Large 16- and 32-bit microprocessors had already been used in board-level designs, and Moore's law ensured that chips would soon be large enough to include both a CPU and other subsystems. Multiple disciplines inform hardwood/ software codesign. Computer architecture tells us about the performance and energy consumption of single CPUs and multiprocessors. Real-time system theory helps analyze the deadline-driven performance of embedded systems. Computer-aided design assists hardware cost evaluation and design-space exploration.
Satellite imagery for studying the UHI as an aid in urban planning
Authors: A. Tal
Venue: Development and application of computer techniques to environmental studies (2002)

The Urban Heat Island (UHI) arises from the essence of urban development i.e the substitution of natural surfaces with vegetative cover, with surfaces of asphalt, concrete and other heat absorbing materials. The thermal image of Tel Aviv-Jaffa, from LANDSAT satellites' thermal band, displays features of cooler and warmer areas, very similar in their distribution over the 11 years and over different seasons studied in this work. From many UHI studies, it is apparent that surface temperatures are influenced by: building density, construction materials, inter-building land-use ( including parking lots), vegetation, directions of main streets with relation to the dominant breeze direction, obstacles to the breeze, human activities - e.g. transportation, industry. Over 50 locations representing the hotter and cooler parts of the city were chosen to investigate this thermal pattern. With cooperation of the Tel Aviv-Jaffa Municipality's GIS unit, tree density, building density and parking lot maps were produced from the relevant data layers . Hand-held camera ground photography was also taken for most of the chosen locations around the city. The determining factor for lower surface temperatures appears to be trees. Even in more densly built areas, trees in inter-building spaces are responsible for reduction of surface temperatures. Furthermore, in some less dense parts of the city with few inter-building trees, the surface temperatures are high. The hottest locations are in general open spaces of bare ground or asphalt covered parking lots or built areas without trees. Tel Aviv-Jaffa is hot and rainless at least 8 months of the year. Therefore, in order to improve the climatic quality of the city and to reduce the use of energy for cooling, it is recommended to aforest the city.An ongoing study for the Ministry of Housing, to be completed during the first quarter of 2002 is a studying of the UHI of 4 other cities in Israel: Beer-Sheva, Haifa, Jerusalem and Natanya - cities in different geographical regions, the objective being to provide government level decision makers with a basis for guidelines for UHI considering urban planning policy.
Global existence for a vector-valued nonlinear heat equation
Authors: Mohammed Aassila
Venue: Nonlinear Analysis: Theory, Methods Applications (2003)

In this paper, we are concerned with the global existence, the uniqueness, the nonnegativity of classical solutions of a semilinear parabolic coupled system.
The advanced encryption standard
Authors: William Stallings
Venue: Cryptologia (2002)

In this paper, we describe the Advanced Encryption Standard (AES), which has been approved after an international competition by the National Institute of Standards and Technology.
Contractions of angles in symmetric cones
Authors: Khalid Koufany
Venue: Publications of the Research Institute for Mathematical Sciences (2002)

For a symmetric cone Ω we compute its Riemannian distance in terms of the singular values of a generalized cross-ratio and prove that the semigroup of the compressions of Ω decreases the compounds distance.
Large-Scale Integer Programs in Image Analysis
Authors: Geir Dahl, Geir Storvik, Alice Fadnes
Venue: Operations Research (2002)

An important problem in image analysis is to segment an image into regions with different class labels. This is relevant in applications in medicine and cartography. In a proper statistical framework this problem may be viewed as a discrete optimization problem. We present two integer linear programming formulations of the problem and study some properties of these models and associated polytopes. Different algorithms for solving these problems are suggested and compared on some realistic data. In particular, a Lagrangian algorithm is shown to have a very promising performance. The algorithm is based on the technique of cost splitting and uses the fact that certain relaxed problems may be solved as shortest path problems.
Admissible minimax estimators of a mean vector of scale mixtures of multivariate normal distributions
Authors: Yuzo Maruyama
Venue: Journal of Multivariate Analysis (2003)

The problem of estimating a mean vector of scale mixtures of multivariate normal distributions with the quadratic loss function is considered. For a certain class of these distributions, which includes at least multivariate-t distributions, admissible minimax estimators are given.
An abstract representation of geometric knowledge for object classification
Authors: Enver Sangineto
Venue: Pattern Recognition Letters (2003)

We propose a new approach to object classification based on the idea of geometric abstraction. A class of objects is described by means of a model which specifies the shape invariants common to all the members of the class. A model is a list of geometric constraints fixing the ranges in which local shape features can vary. We also propose an efficient algorithm for constraint satisfaction and we show the computational and descriptive advantages of our proposal with respect to other classification approaches based on average prototype models.