ppxscal/embedding_network huggingface dataset:
Individual differences in exploration using desktop VR
Authors: David Modjeska, Mark Chignell
Venue: Journal of the American Society for Information Science and Technology (2003)

With advances in computer graphics, a number of innovative approaches to information visualization have been developed (e.g., Card et al, 1991). Some of these approaches create a mapping between information and corresponding structure in a virtual world. The resulting virtual worlds can be fully three dimensional (3D) or they can be implemented as a series of 2D birds-eye "snapshots" that are traversed as if they were in 3D, using operations such as panning and zooming interactively (2.5D). This paper reports a study that contrasted 3D and 2.5D performance for people with differing levels of spatial and structure learning ability. Four data collection methods were employed: search task scoring; subjective questionnaires; navigational activity logging and analysis; and administration of tests for spatial and structure-learning abilities. Analysis of the results revealed statistically significant effects of user abilities, and information environment designs. Overall, this research did not find a performance advantage for using a 3D rather than a 2.5D virtual world. In addition, users in the lowest quartile of spatial ability had significantly lower search performance in the 3D environment. The findings suggest that individual differences in traits such as spatial ability may be important in determining the usability and acceptability of 3D environments.
A Scalable Dual-Field Elliptic Curve Cryptographic Processor
Authors: Akashi Satoh, Kohji Takano
Venue: IEEE Transactions on Computers (2003)

We propose an elliptic curve (EC) cryptographic processor architecture that can support Galois fields {\rm GF}(p) and {\rm GF}(2^n) for arbitrary prime numbers and irreducible polynomials by introducing a dual field multiplier. A Montgomery multiplier with an optimized data bus and an on-the-fly redundant binary converter boost the throughput of the EC scalar multiplication. All popular cryptographic functions such as DSA, EC-DSA, RSA, CRT, and prime generation are also supported. All commands are organized in a hierarchical structure according to their complexity. Our processor has high scalability and flexibility between speed, hardware area, and operand size. In the hardware evaluation using a 0.13-\mum CMOS standard cell library, the high-speed design using 117.5 Kgates with a 64-bit multiplier achieved operation times of 1.21 ms and 0.19 ms for a 160-bit EC scalar multiplication in {\rm GF}(p) and {\rm GF}(2^n), respectively. A compact version with an 8-bit multiplier requires only 28.3K gates and executes the operations in 7.47 ms and 2.79 ms. Not only 160-bit operations, but any bit length can be supported by any hardware configuration so long as the memory capacity is sufficient.
Genetic Mining of HTML Structures for Effective Web-Document Retrieval
Authors: Sun Kim, Byoung-Tak Zhang
Venue: Applied Intelligence (2003)

Web-documents have a number of tags indicating the structure of texts. Text segments marked by HTML tags have specific meaning which can be utilized to improve the performance of document retrieval systems. In this paper, we present a machine learning approach to mine the structure of HTML documents for effective Web-document retrieval. A genetic algorithm is described that learns the importance factors of HTML tags which are used to re-rank the documents retrieved by standard weighting schemes. The proposed method has been evaluated on artificial text sets and a large-scale TREC document collection. Experimental evidence supports that the tag weights are well trained by the proposed algorithm in accordance with the importance factors for retrieval, and indicates that the proposed approach significantly improves the performance in retrieval accuracy. In particular, the use of the document-structure mining approach tends to move relevant documents to upper ranks, which is especially important in interactive Web-information retrieval environments.
The cache behaviour of large lazy functional programs on stock hardware
Authors: Nicholas Nethercote, Alan Mycroft
Venue: ACM SIGPLAN Notices (2003)

Lazy functional programs behave differently from imperative programs and these differences extend to cache behaviour. We use hardware counters and a simple yet accurate execution cost model to analyse some large Haskell programs on the x86 architecture. The programs do not interact well with modern processors---L2 cache data miss stalls and branch misprediction stalls account for up to 60% and 32% of execution time respectively. Moreover, the program code exhibits little exploitable instruction-level parallelism.We then use simulation to pinpoint cache misses at the instruction level. With this information we apply prefetching to minimise the cost of write misses, speeding up Haskell programs by up to 22%. We conclude with more ideas for changing the Glasgow Haskell Compiler and its garbage collector to improve the cache performance of large programs.
Analysis of coupled oceanographic and acoustic solition simulations in the Yellow Sea: a search for solition-induced resonances
Authors: S. A. Chin-Bing, A. Warn-Varnas, D. B. King, K. G. Lamb, M. Teixeira, J. A. Hawkins
Venue: Mathematics and Computers in Simulation (2003)

The area south of the Shandong peninsula has been of great interest to both oceanographers and underwater acousticians due to the measurements of Zhou et al. [J. Acoust. Soc. Am. 90 (1991) 2042]. Over a period of years, in the summer, they observed anomalous losses in shallow water acoustic signals. They attributed the losses to acoustic mode conversions produced by solitary internal waves (solitons). Their hypothesis remains unsubstantiated due to a scarcity of oceanographic measurements in this area. In this simulation study the non-hydrostatic, 2.5-dimensional Lamb model was used to generate solitons in an adjacent, deeper area than that examined by Zhou et al. [J. Acoust. Soc. Am. 90 (1991) 2042]. Topographic variations and semi-diurnal tidal strength magnitudes were obtained from digital atlases and published data. For summer conditions, the Lamb model simulations showed that the existing semi-diurnal tidal flow over the topographic variations could lead to the formulation of internal bores and solitons. SAR observations of solitons near this region were used to select parameters and initialize the Lamb model. The resulting soliton simulations were comparable to the two-dimensional surface spectra seen in the SAR data. Soliton amplitudes of 2-7 m were indicated. Acoustic studies were made using the highly accurate finite element parabolic equation (FEPE) acoustic model applied to the initial soliton state data generated by the Lamb model. Mode decomposition of the acoustic fields in the deeper region showed that the mode conversions necessary for anomalous signal losses were present. These findings are consistent with the soliton hypothesis made by Zhou et al.
Supply-Chain Management for Recoverable Manufacturing Systems
Authors: V. Daniel R. Guide, Vaidyanathan Jayaraman, Rajesh Srivastava, W. C. Benton
Venue: Interfaces (2000)

Recoverable manufacturing systems minimize the environmental impact of industry by reusing materials, reducing energy use, and reducing the need to landfill industrial products. These systems are widespread in the United States and are profitable, in addition to contributing to sustainable development. However, the management of supply-chain activities can differ greatly from management activities in traditional manufacturing supply chains. Seven complicating characteristics increase uncertainty. Managers must take actions to reduce uncertainty in the timing and quantity of returns, balance return rates with demand rates, and make material recovery more predictable. Managers must also plan for the collection of products from end-users. The use of information systems with new production-planning and control techniques makes management of these activities more predictable.
Markov chain Monte Carlo exact inference for binomial and multinomial logistic regression models
Authors: Jonathan J. Forster, John W. Mcdonald, Peter W. F. Smith
Venue: Statistics and Computing (2003)

We develop Metropolis-Hastings algorithms for exact conditional inference, including goodness-of-fit tests, confidence intervals and residual analysis, for binomial and multinomial logistic regression models. We present examples where the exact results, obtained by enumeration, are available for comparison. We also present examples where Monte Carlo methods provide the only feasible approach for exact inference.
Hensel lifting and bivariate polynomial factorisation over finite fields
Authors: Shuhong Gao, Alan G. B. Lauder
Venue: Mathematics of Computation (2002)

This paper presents an average time analysis of a Hensel lifting based factorisation algorithm for bivariate polynomials over finite fields. It is shown that the average running time is almost linear in the input size. This explains why the Hensel lifting technique is fast in practice for most polynomials.
Parallel implementation of the split-step and the pseudospectral methods for solving higher KdV equation
Authors: Jinhua Guo, Thiab R. Taha
Venue: Mathematics and Computers in Simulation (2003)

Numerical simulations show that higher order KdV equation under certain conditions has a self-focusing singularity, which means that the solution of the equation blows up in finite time. In this paper, two numerical schemes: the split-step Fourier transform and the pseudospectral methods are used to investigate this self-focusing singularity problem. Parallel algorithms for the proposed schemes are designed and implemented. FFTW-MPI algorithm designed by Matteo Frigo and Steven Johnson is used for parallel implementation of the discrete Fourier transform (DFT). The parallel algorithms are implemented on an SGI Origin 2000 multiprocessor computer and experiments show that a considerable speedup is attained.
Multivariate Standardized Time Series for Steady-State Simulation Output Analysis
Authors: David F. Muñoz, Peter W. Glynn
Venue: Operations Research (2001)

The theory of standardized time series, initially proposed to estimate a single steady-state mean from the output of a simulation, is extended to the case where more than one steady-state mean is to be estimated simultaneously. Under mild assumptions on the stochastic process representing the output of the simulation, namely a functional central limit theorem, we obtain asymptotically valid confidence regions for a (multivariate) steady-state mean based on multivariate standardized time series. We provide examples of multivariate standardized time series, including the multivariate versions of the batch means method and Schruben's standardized sum process. Large-sample properties of confidence regions obtained from multivariate standardized time series are discussed. We show that, as in the univariate case, the asymptotic expected volume of confidence regions produced by standardized time series procedures is larger than that obtained from a consistent estimation procedure. We present and discuss experimental results that illustrate our theory.
Program slicing for codesign
Authors: Jeffry T Russell
Venue: Proceedings of the tenth international symposium on Hardware/software codesign (2002)

Program slicing is a software analysis technique that computes the set of operations in a program that may affect the computation at a particular operation. Interprocedural slicing techniques have separately addressed concurrent programs and hardware description languages. However, application of slicing to codesign of embedded systems requires dependence analysis across the hardware-software interface.We extend program slicing for a codesign environment. Hardware-software interactions common in component-based systems are mapped to previously introduced dependences, including the interference and signal dependences. We introduce a novel access dependence that models a memory access side effect that results in activation of a process. A slicing algorithm that incorporates this variety of dependences is described.
A methodology to improve object oriented database systems with fuzzy types
Authors: Nicolás Marín, Olga Pons, Ignacio J. Blanco, María Amparo Vila
Venue: Technologies for constructing intelligent systems: Tasks (2002)

Fuzzy Types are a desirable feature that an Object Oriented Database System (OODB) must have in order to deal with vague structures. This kind of types are defined by means of different levels of precision or amplitude where properties are ordered according to their relationship with the concept represented by the type. The implementation of this new tool can be made building a new layer on an existing OODB, avoiding the development of a whole system which incorporates fuzzy types as an intrinsic characteristic. In this paper, we explain how the typical classes of an OODB can be used in order to represent a fuzzy type. New mechanisms of instantiation and inheritance are also modeled using this approach.
A Conceptual Model and Algebra for On-Line Analytical Processing in Decision Support Databases
Authors: Helen Thomas, Anindya Datta
Venue: Information Systems Research (2001)

Data warehousing and On-Line Analytical Processing (OLAP) are two of the most significant new technologies in the business data processing arena. A data warehouse, or decision support database, can be defined as a "very large" repository of historical data pertaining to an organization. OLAP refers to the technique of performing complex analysis over the information stored in a data warehouse. The complexity of queries required to support OLAP applications makes it difficult to implement using standard relational database technology. Moreover, currently there is no standard conceptual model for OLAP. There clearly is a need for such a model and an algebra as evidenced by the numerous SQL extensions offered by many vendors of OLAP products. In this paper we address this issue by proposing a model of a data cube and an algebra to support OLAP operations on this cube. The model we present is simple and intuitive, and the algebra provides a means to concisely express complex OLAP queries.
Asynchronous 2-D discrete cosine transform core processor
Authors: Bret Stott, Dave Johnson, Venkatesh Akella
Venue: Proceedings of the 1995 International Conference on Computer Design: VLSI in Computers and Processors (1995)

To lend additional insight into the reality of self-timed design, this paper proposes a large-scale, application specific, asynchronous design-a CCITT compatible asynchronous DCT/IDCT processor. The prototype DCT/IDCT processor uses two-phase transition signaling and a bounded delay approach to implement a modified version of Sutherland's micropipeline. The layout of the core processor was designed using standard cell and custom techniques to integrate 150,000 transistors in a 2 /spl mu/ SCMOS technology. This investigation presents the prototype DCT/IDCT processor design and the resulting measures of speed, power, and area.
Planar C2 cubic spline interpolation under geometric boundary conditions
Authors: A. I. Ginnis, P. D. Kaklis
Venue: Computer Aided Geometric Design (2002)

This paper deals with the problem of C2 cubic spline interpolation under geometric boundary conditions, that is, fixing the unit-tangent vector and the curvature at the end points of a planar point-set. The solvability of the resulting non-linear problem, which is equivalent to a quadratic system with respect to the lengths of the boundary tangent vectors, is exhaustively studied, leading to necessary and sufficient conditions for all possible boundary-data configurations. A robust scheme for the numerical solution of the quadratic system is presented, and the use of the new boundary conditions is illustrated in the context of three examples.
A single-element extension of antimatroids
Authors: Masataka Nakamura
Venue: Discrete Applied Mathematics (2002)

An antimatroid is a family of sets which is accessible, closed under union, and includes an empty set. A number of examples of antimatroids arise from various kinds of shellings and searches on combinatorial objects, such as, edge/node shelling of trees, poset shelling, node-search on graphs, etc. (Discrete Math. 78 (1989) 223; Geom. Dedicata 19 (1985) 247; Greedoids, Springer, Berlin, 1980) [1-3]. We introduce a one-element extension of antimatroids, called a lifting, and the converse operation, called a reduction. It is shown that a family of sets is an antimatroid if and only if it is constructed by applying lifting repeatedly to a trivial lattice. Furthermore, we introduce two specific types of liftings, 1-lifting and 2-lifting, and show that a family of sets is an antimatroid of poset shelling if and only if it is constructed from a trivial lattice by repeating 1-lifting. Similarly, an antimatroid of edge-shelling of a tree is shown to be constructed by repeating 2-lifting, and vice versa.
On the linear independence measure of logarithms of rational numbers
Authors: Qiang Wu
Venue: Mathematics of Computation (2003)

In this paper we give a general theorem on the linear independence measure of logarithms of rational numbers and, in particular, the linear independence measure of 1, log 2, log 3, log 5 and of 1, log 2, log 3, log 5, log 7. We also give a method to search for polynomials of smallest norm on a real interval [a,b] which may be suitable for computing or improving the linear independence measure of logarithms of rational numbers.
Talking with Erol Gelenbe
Authors: Ubiquity staff
Venue: Ubiquity (2002)

An international perspective on ubiquitous computing and university education.
Preprocessing of intractable problems
Authors: Marco Cadoli, Francesco M. Donini, Paolo Liberatore, Marco Schaerf
Venue: Information and Computation (2002)

Some computationally hard problems, e.g., deduction in logical knowledge bases- are such that part of an instance is known well before the rest of it, and remains the same for several subsequent instances of the problem. In these cases, it is useful to preprocess off-line this known part so as to simplify the remaining on-line problem. In this paper we investigate such a technique in the context of intractable, i.e., NP-hard, problems. Recent results in the literature show that not all NP-hard problems behave in the same way: for some of them preprocessing yields polynomial-time on-line simplified problems (we call them compilable), while for other ones their compilability implies some consequences that are considered unlikely. Our primary goal is to provide a sound methodology that can be used to either prove or disprove that a problem is compilable. To this end, we define new models of computation, complexity classes, and reductions. We find complete problems for such classes, "completeness" meaning they are "the less likely to be compilable." We also investigate preprocessing that does not yield polynomial-time on-line algorithms, but generically "decreases" complexity. This leads us to define "hierarchies of compilability," that are the analog of the polynomial hierarchy. A detailed comparison of our framework to the idea of "parameterized tractability" shows the differences between the two approaches.
Computing the nonnull asymptotic variance and the asymptotic relative efficiency of Spearman's rank correlation
Authors: Craig B. Borkowf
Venue: Computational Statistics Data Analysis (2002)

Over the past century, Spearman's rank correlation, ρs, has become one of the most commonly used nonparametric statistics, yet much remains unknown about its finite and asymptotic behavior. This paper presents a method for computing the asymptotic variance of the point estimate, ρs, in terms of expectations of the joint and marginal distribution functions, for any underlying bivariate distribution that satisfies minimal regularity conditions. Also presented are numerical results for certain bivariate distributions of interest in order to demonstrate that distributions with similar values of Pearson's or Spearman's correlations can yield surprisingly different values for the asymptotic variance of ρs. In particular, these results emphasize that one should not use certain standard procedures for hypothesis testing and confidence interval construction that assume bivariate normality without first checking this distributional assumption. Finally, these numerical results are used to compute the asymptotic relative efficiency of Spearman's rank correlation compared to Pearson's correlation.
The Social Capital of French and American Managers
Authors: Ronald S. Burt, Robin M. Hogarth, Claude Michaud
Venue: Organization Science (2000)

Accumulating empirical evidence on American managers shows that social-capital effects on performance are a function of the information and control benefits of bridging structural holes--the disconnections between nonredundant contacts in a network. Is that network form of social capital unique to Americans? France seemed to us a productive site for comparative research because the image from past research is that French managers are more regulated than Americans; more regulated by bureaucratic authority and more regulated by peer pressure, with both amplified by the greater reliance in France on internal labor markets. People comfortable with knowing their place in a chain of bureaucratic control could be uncomfortable with the negotiated control exercised by network entrepreneurs, so the positive association between structural holes and performance in the United States could be negligible or even reversed for French managers.We use network and performance data on two study populations of senior managers, one in France and one in the United States, to describe social capital similarities and differences between the populations. The network form of social capital is similar in the two populations: More successful French managers, like Americans, tend to have networks rich in structural holes. The French and American managers make similar distinctions between kinds of relationships. Relations that bridge structural holes are similarly detached from routine work activities for the French and the Americans. The interesting difference is that social capital develops differently in the two populations. The French managers operate with a less porous social boundary around their firm and associate negative emotions with bridge relations. Reinforcing Aix-en-Provence observations on the significance of adult education for Franco-German differences in organization, we find that exposure to peers in other firms via executive education is for our French managers the only factor positively associated with the social capital of bridge relationships.
Control flow analysis of mobile ambients with security boundaries
Authors: Chiara Braghin, Agostino Cortesi, Riccardo Focardi
Venue: Proceedings of the IFIP TC6/WG6.1 Fifth International Conference on Formal Methods for Open Object-Based Distributed Systems V (2002)

A multilevel security policy is considered in the scenario of mobile systems, and modeled within "pure" Mobile Ambients calculus, in which no communication channels are present and the only possible actions are represented by the moves performed by mobile processes. The information flow property of interest is defined in terms of the possibility for a confidential ambient/data to move outside a security boundary. In a previous paper, we gave a very simple syntactic property that is sufficient to imply the absence of unwanted information flows. In this paper, a control flow analysis is defined, as a refinement of the Hansen-Jensen-Nielsons's CFA, that allows to capture boundary crossings with better accuracy.