ppxscal/embedding_network huggingface dataset:
A comparative analysis of the use of NOAA-AVHRR NDVI and FWI data for forest fire risk assessment
Authors: A. Gabban, J. San-Miguel-Ayanz, D. X. Viegas
Venue: International Journal of Remote Sensing (2008)

Fires are a major hazard to forests in the Mediterranean region, where, on average, half a million hectares of forested areas are burned every year. The assessment of fire risk is therefore at the heart of fire prevention policies in the region. The estimation of forest fire risk often involves the integration of meteorological and other fuel-related variables, leading to an index that assesses the different levels of risk. Two indices frequently used to estimate the level of fire risk are the Fire Weather Index (FWI) and the Normalized Difference Vegetation Index (NDVI). Although a correlation between the number of fires and the level of risk determined by these indices has been demonstrated in previous studies, the analyses focused on the changes in fire risk levels in areas where fires took place. The present study analyses the behaviour of the fire risk indices not only in areas where fires occurred but also in areas where fires did not take place. Specifically, the objective of this work was to compare the potential of the two indices to discriminate different levels of fire risk over large areas. Qualitative and quantitative methods were used to compare the statistical distributions of fire event frequencies with those of fire risk levels. The qualitative method highlights graphically the statistical difference between the values of the indices computed over burnt areas and the overall distribution of the values of the indices. The quantitative method, based on the use of the so-called performance index, was used to evaluate and compare numerically the potential of the indices. The analyses were performed considering very extensive datasets of fire events, satellite data and meteorological data for Spain during a 10-year period. Although the NDVI is assumed to describe the vegetation status as related to fire ignition, the results show conclusively an enhanced performance of the FWI over the NDVI in identifying areas at risk of fires.
Mathematical models of some nonlinear systems and their computer realization
Authors: V. N. Seredenko
Venue: Cybernetics and Systems Analysis (2008)

A model of an interphase layer in composite media is investigated. Functional spaces are introduced and general operator equations are constructed that include operators of interface conditions in addition to boundary conditions. Projective-iterative methods for solving operator equations in the stationary case are considered. The result of computer realization of an inhomogeneous nonlinear boundary-value problem is illustrated.
Large-scale computation of elementary flux modes with bit pattern trees
Authors: Marco Terzer, Jörg Stelling
Venue: Bioinformatics (2008)

Motivation: Elementary flux modes (EFMs)—non-decomposable minimal pathways—are commonly accepted tools for metabolic network analysis under steady state conditions. Valid states of the network are linear superpositions of elementary modes shaping a polyhedral cone (the flux cone), which is a well-studied convex set in computational geometry. Computing EFMs is thus basically equivalent to extreme ray enumeration of polyhedral cones. This is a combinatorial problem with poorly scaling algorithms, preventing the large-scale analysis of metabolic networks so far. Results: Here, we introduce new algorithmic concepts that enable large-scale computation of EFMs. Distinguishing extreme rays from normal (composite) vectors is one critical aspect of the algorithm. We present a new recursive enumeration strategy with bit pattern trees for adjacent rays—the ancestors of extreme rays—that is roughly one order of magnitude faster than previous methods. Additionally, we introduce a rank updating method that is particularly well suited for parallel computation and a residue arithmetic method for matrix rank computations, which circumvents potential numerical instability problems. Multi-core architectures of modern CPUs can be exploited for further performance improvements. The methods are applied to a central metabolism network of Escherichia coli, resulting in ≈26 Mio. EFMs. Within the top 2% modes considering biomass production, most of the gain in flux variability is achieved. In addition, we compute ≈5 Mio. EFMs for the production of non-essential amino acids for a genome-scale metabolic network of Helicobacter pylori. Only large-scale EFM analysis reveals the >85% of modes that generate several amino acids simultaneously. Availability: An implementation in Java, with integration into MATLAB and support of various input formats, including SBML, is available at http://www.csb.ethz.ch in the tools section; sources are available from the authors upon request. Contact: joerg.stelling@inf.ethz.ch Supplementary information:Supplementary data are available at Bioinformatics online.
Simulation of electromagnetic devices using coupled models
Authors: Ion Cârstea, Daniela Cârstea, Alexandru Adrian Cârstea
Venue: WSEAS Transactions on Systems and Control (2007)

This work presents numerical algorithms for simulation of distributed-parameter systems with direct applications in electrical engineering. The algorithms are developed in the context of the finite element method. Many works in the professional literature present coupled models for the electromagnetic devices and this work is toward this direction with emphasis on the development of efficient algorithms in numerical computation of the coupled models. Our work describes the solution of coupled electromagnetic and heat dissipation problems in two dimensions and cylindrical-coordinates system for devices with cylindrical symmetry. The purpose of the work is to define both conventional algorithms and parallel algorithms for coupled problems in context of the finite element method. The mathematical models for electromagnetic field are based on potential formulations. Some numerical results are presented.
hRESTS: An HTML Microformat for Describing RESTful Web Services
Authors: Jacek Kopecký, Karthik Gomadam, Tomas Vitvar
Venue: Proceedings of the 2008 IEEE/WIC/ACM International Conference on Web Intelligence and Intelligent Agent Technology - Volume 01 (2008)

The Web 2.0 wave brings, among other aspects, the Programmable Web:increasing numbers of Web sites provide machine-oriented APIs and Web services. However, most APIs are only described with text in HTML documents. The lack of machine-readable API descriptions affects the feasibility of tool support for developers who use these services. We propose a microformat called hRESTS (HTML for RESTful Services) for machine-readable descriptions of Web APIs, backed by a simple service model. The hRESTS microformat describes main aspects of services, such as operations, inputs and outputs. We also present two extensions of hRESTS:SA-REST, which captures the facets of public APIs important for mashup developers, and MicroWSMO, which provides support for semantic automation.
Distance-2 Self-stabilizing Algorithm for a b-Coloring of Graphs
Authors: Lyes Dekar, Hamamache Kheddouci
Venue: Proceedings of the 10th International Symposium on Stabilization, Safety, and Security of Distributed Systems (2008)

A b-coloring of a graph G is a proper k-coloring of G such that for each color i, 1 &le; i &le; k, at least one vertex colored with i is adjacent to every color j, with 1 &le; j &ne; i &le; k. This kind of coloring is useful to decompose any system into communities, where each community contains a vertex adjacent to all the other communities. This kind of organization can provide improving in many fields, especially in the data clustering. In this paper we propose a new self-stabilizing algorithm for finding a b-coloring of arbitrary undirected connected graphs. Because the characteristics of the b-coloring problem, the proposed self-stabilizing algorithm use a distance-2 knowledge.
Frequency characteristics of the one-layer anisotropic magnetoresistive sensitive nanoelements
Authors: S. I. Kasatkin, D. V. Vagin, P. A. Polyakov, O. P. Polyakov
Venue: Automation and Remote Control (2008)

The high-frequency characteristics of the one-layer anisotropic magnetoresistive strip--the magnetosensitive nanoelement of the magnetic field sensor--were analyzed on the basis of the Landau-Livshits-Hilbert equation. The results of this study were shown to coincide completely with the linear microwave theory. The strip frequency characteristics were analyzed for low-anisotropy and high-anisotropy FeNiCo ferromagnetic films of various thickness, strip width, easy magnetization direction, and fixed external magnetic field.
Towards an information model of consistency maintenance in distributed interactive applications
Authors: Xin Zhang, Tomás E. Ward, Séamus McLoone
Venue: International Journal of Computer Games Technology (2008)

A novel framework to model and explore predictive contract mechanisms in distributed interactive applications (DIAs) using information theory is proposed. In our model, the entity state update scheme is modelled as an information generation, encoding, and reconstruction process. Such a perspective facilitates a quantitative measurement of state fidelity loss as a result of the distribution protocol. Results from an experimental study on a first-person shooter game are used to illustrate the utility of this measurement process. We contend that our proposed model is a starting point to reframe and analyse consistency maintenance in DIAs as a problem in distributed interactive media compression.
Animating skin with wrinkles using curvature evolution and energy minimization
Authors: Suresh Kumar Lodha
Venue:  (2008)

Modeling and animating skin with wrinkles is very important for character animation in films and games. To model wrinkles, it is important to consider all aspects that influence the formation of wrinkles such as skin texture and physiology, mathematics of elasticity, geometry and the associated physics behind the wrinkling phenomenon, and integrate these techniques efficiently. A number of previous approaches, including physically-based modeling, geometric wrinkling, texture or bump mapping, have tried to model skin with wrinkles; however, realistic and computationally efficient modeling of skin with wrinkles remain a challenge. In this dissertation, we propose an integrated physiology and physically-based geometric model of skin that allows dynamic formation of wrinkles suitable for animation. The physics of wrinkling involves the study of large deformations of naturally thin elastic sheets and is governed by a set of nonlinear partial differential equations that are very difficult to solve. Instead, we model the wrinkling of skin as curvature-driven evolution of one-dimensional profile curves (sampled from the skin mesh through intersections with a cutting plane) that allows for singularities. Skin elasticity is captured using an energy functional defined by skin stretching, bending, interacting with underlying components, and constrained by self-collisions. The proposed solution determines skin motion by seeking its minimal energy configuration; fast convergence of the numerical solution is ensured through a good initial estimate formulated using careful placement of joint vertices. The regularity of skin deformation allows us to dynamically reconstruct the 2D skin mesh from the 1D profile curve animations. This two-step approach is computationally lightweight. Our energy minimization solutions converge in quick time without the use of any special purpose hardware. Our model sizes are compact and storage-efficient since the wrinkles are generated on-the-fly through a parameterized subdivision of the wrinkles triangles during animation. These parameterizations are intuitive and allow the animator to control the width and depth of the wrinkles as well as the height of the folds surrounding the wrinkles. Our approach allows realistic skin animation by supporting automatic generation of wrinkles and smooth motion of skin joints. We have implemented the proposed modeling and animation system for skin with dynamic wrinkling in C++ which allows a user to control the parametrizations, extract profile curves, identify the anchors, and define association between profile curve and skin mesh vertices automatically. We have applied our system to animate skin on the human finger with wrinkles.
Motion Planning for Haptic Guidance
Authors: Jan Rosell, Carlos Vázquez, Alexander Pérez, Pedro Iñiguez
Venue: Journal of Intelligent and Robotic Systems (2008)

Haptic devices allow a user to feel either reaction forces from virtual interactions or reaction forces reflected from a remote site during a bilateral teleoperation task. Also, guiding forces can be exerted to train the user in the performance of a virtual task or to assist him/her to safely teleoperate a robot. The generation of guiding forces relies on the existence of a motion plan that provides the direction to be followed to reach the goal from any free configuration of the configuration space ( ${\mathcal C}$ -space). This paper proposes a method to obtain such a plan that interleaves a sampling-based exploration of ${\mathcal C}$ -space with an efficient computation of harmonic functions. A deterministic sampling sequence (with a bias based on harmonic function values) is used to obtain a hierarchical cell decomposition model of ${\mathcal C}$ -space. A harmonic function is iteratively computed over the partially known model using a novel approach. The harmonic function is the navigation function used as motion plan. The approach has been implemented in a planner (called the Kautham planner) that, given an initial and a goal configuration, provides: (a) a channel of cells connecting the cell that contains the initial configuration with the cell that contains the goal configuration; (b) two harmonic functions over the whole ${\mathcal C}$ -space, one that guides motions towards the channel and another that guides motions within the channel towards the goal; and (c) a path computed over a roadmap built with the free samples of the channel. The harmonic functions and the solution path are then used to generate the guiding forces for the haptic device. The planning approach is illustrated with examples on 2D and 3D workspaces.
CollaboraTV: making television viewing social again
Authors: Mukesh Nathan, Chris Harrison, Svetlana Yarosh, Loren Terveen, Larry Stead, Brian Amento
Venue: Proceeding of the 1st international conference on Designing interactive user experiences for TV and video (2008)

With the advent of video-on-demand services and digital video recorders, the way in which we consume media is undergoing a fundamental change. People today are less likely to watch shows at the same time, let alone the same place. As a result, television viewing, which was once a social activity, has been reduced to a passive and isolated experience. To study this issue, we developed a system called CollaboraTV and demonstrated its ability to support the communal viewing experience through a month-long field study. Our study shows that users understand and appreciate the utility of asynchronous interaction, are enthusiastic about CollaboraTV's engaging social communication primitives and value implicit show recommendations from friends. Our results both provide a compelling demonstration of a social television system and raise new challenges for social television communication modalities.
A new approach to evaluating novel recommendations
Authors: Òscar Celma, Perfecto Herrera
Venue: Proceedings of the 2008 ACM conference on Recommender systems (2008)

This paper presents two methods, named Item- and User-centric, to evaluate the quality of novel recommendations. The former method focuses on analyzing the item-based recommendation network. The aim is to detect whether the network topology has any pathology that hinders novel recommendations. The latter, user-centric evaluation, aims at measuring users' perceived quality of novel, previously unknown, recommendations. The results of the experiments, done in the music recommendation context, show that last.fm social recommender, based on collaborative filtering, is prone to popularity bias. This has direct consequences on the topology of the item-based recommendation network. Pure audio content-based methods (CB) are not affected by popularity. However, a user-centric experiment done with 288 subjects shows that even though a social-based approach recommends less novel items than our CB, users' perceived quality is better than those recommended by a pure CB method.
Adapting information retrieval systems to user queries
Authors: Giridhar Kumaran, James Allan
Venue: Information Processing and Management: an International Journal (2008)

Users enter queries that are short as well as long. The aim of this work is to evaluate techniques that can enable information retrieval (IR) systems to automatically adapt to perform better on such queries. By adaptation we refer to (1) modifications to the queries via user interaction, and (2) detecting that the original query is not a good candidate for modification. We show that the former has the potential to improve mean average precision (MAP) of long and short queries by 40% and 30% respectively, and that simple user interaction can help towards this goal. We observed that after inspecting the options presented to them, users frequently did not select any. We present techniques in this paper to determine beforehand the utility of user interaction to avoid this waste of time and effort. We show that our techniques can provide IR systems with the ability to detect and avoid interaction for unpromising queries without a significant drop in overall performance.
Doloto: code splitting for network-bound web 2.0 applications
Authors: Benjamin Livshits, Emre Kiciman
Venue: Proceedings of the 16th ACM SIGSOFT International Symposium on Foundations of software engineering (2008)

Modern Web 2.0 applications, such as GMail, Live Maps, Face-book and many others, use a combination of Dynamic HTML, JavaScript and other Web browser technologies commonly referred to as AJAX to push application execution to the client web browser. This improves the responsiveness of these network-bound applications, but the shift of application execution from a back-end server to the client also often dramatically increases the amount of code that must first be downloaded to the browser. This creates an unfortunate Catch-22: to create responsive distributed Web 2.0 applications developers move code to the client, but for an application to be responsive, the code must first be transferred there, which takes time. In this paper, we present Doloto, an optimization tool for Web 2.0 applications. Doloto analyzes application workloads and automatically rewrites the existing application code to introduce dynamic code loading. After being processed by Doloto, an application will initially transfer only the portion of code necessary for application initialization. The rest of the application's code is replaced by short stubs---their actual implementations are transfered lazily in the background or, at the latest, on-demand on first execution of a particular application feature. Moreover, code that is rarely executed is rarely downloaded to the user browser. Because Doloto significantly speeds up the application startup and since subsequent code download is interleaved with application execution, applications rewritten with Doloto appear much more responsive to the end-user. To demonstrate the effectiveness of Doloto in practice, we have performed experiments on five large widely-used Web 2.0 applications. Doloto reduces the size of application code download by hundreds of kilobytes or as much as 50% of the original download size. The time to download and begin interacting with large applications is reduced by 20--40% depending on the application and wide-area network conditions. Doloto especially shines on wireless and mobile connections, which are becoming increasingly important in today's computing environments.
Avoiding monotony: improving the diversity of recommendation lists
Authors: Mi Zhang, Neil Hurley
Venue: Proceedings of the 2008 ACM conference on Recommender systems (2008)

The primary premise upon which top-N recommender systems operate is that similar users are likely to have similar tastes with regard to their product choices. For this reason, recommender algorithms depend deeply on similarity metrics to build the recommendation lists for end-users. However, it has been noted that the products offered on recommendation lists are often too similar to each other and attention has been paid towards the goal of improving diversity to avoid monotonous recommendations. Noting that the retrieval of a set of items matching a user query is a common problem across many applications of information retrieval, we model the competing goals of maximizing the diversity of the retrieved list while maintaining adequate similarity to the user query as a binary optimization problem. We explore a solution strategy to this optimization problem by relaxing it to a trust-region problem.This leads to a parameterized eigenvalue problem whose solution is finally quantized to the required binary solution. We apply this approach to the top-N prediction problem, evaluate the system performance on the Movielens dataset and compare it with a standard item-based top-N algorithm. A new evaluation metric ItemNovelty is proposed in this work. Improvements on both diversity and accuracy are obtained compared to the benchmark algorithm.
Mining non-redundant high order correlations in binary data
Authors: Xiang Zhang, Feng Pan, Wei Wang, Andrew Nobel
Venue: Proceedings of the VLDB Endowment (2008)

Many approaches have been proposed to find correlations in binary data. Usually, these methods focus on pair-wise correlations. In biology applications, it is important to find correlations that involve more than just two features. Moreover, a set of strongly correlated features should be non-redundant in the sense that the correlation is strong only when all the interacting features are considered together. Removing any feature will greatly reduce the correlation. In this paper, we explore the problem of finding non-redundant high order correlations in binary data. The high order correlations are formalized using multi-information, a generalization of pairwise mutual information. To reduce the redundancy, we require any subset of a strongly correlated feature subset to be weakly correlated. Such feature subsets are referred to as Non-redundant Interacting Feature Subsets (NIFS). Finding all NIFSs is computationally challenging, because in addition to enumerating feature combinations, we also need to check all their subsets for redundancy. We study several properties of NIFSs and show that these properties are useful in developing efficient algorithms. We further develop two sets of upper and lower bounds on the correlations, which can be incorporated in the algorithm to prune the search space. A simple and effective pruning strategy based on pair-wise mutual information is also developed to further prune the search space. The efficiency and effectiveness of our approach are demonstrated through extensive experiments on synthetic and real-life datasets.