ppxscal/embedding_network huggingface dataset:
Symbol timing estimation in MIMO correlated flat-fading channels: Research Articles
Authors: Yik-Chung Wu, Erchin Serpedin
Venue: Wireless Communications Mobile Computing (2004)

In this paper, the data aided (DA) and non-data aided (NDA) maximum likelihood (ML) symbol timing estimators and their corresponding conditional Cramer&ndash;Rao bound (CCRB) and modified Cramer&ndash;Rao bound (MCRB) in multiple-input-multiple-output (MIMO) correlated flat-fading channels are derived. It is shown that the approximated ML algorithm in References [4,13] is just a special case of the DA ML estimator; while the extended squaring algorithm in Reference [14] is just a special case of the NDA ML estimator. For the DA case, the optimal orthogonal training sequences are also derived. It is found that the optimal orthogonal sequences resemble the Walsh sequences, but present different envelopes. Simulation results under different operating conditions (e.g. number of antennas and correlation between antennas) are given to assess and compare the performances of the DA and NDA ML estimators with respect to their corresponding CCRBs and MCRBs. It is found that (i) the mean square error (MSE) of the DA ML estimator is close to the CCRB and MCRB, (ii) the MSE of the NDA ML estimator is close to the CCRB but not to the MCRB, (iii) the MSEs of both DA and NDA ML estimators are approximately independent of the number of transmit antennas and are inversely proportional to the number of receive antennas, (iv) correlation between antennas has little effect on the MSEs of DA and NDA ML estimators and (v) DA ML estimator performs better than NDA ML estimator at the cost of lower transmission efficiency and higher implementation complexity. Copyright &copy; 2004 John Wiley & Sons, Ltd.
Linearity and nondeletion on monadic context-free tree grammars
Authors: Akio Fujiyoshi
Venue: Information Processing Letters (2005)

In this paper, subclasses of monadic context-free tree grammars (CFTGs) are compared. Since linear, nondeleting, monadic CFTGs generate the same class of string languages as tree adjoining grammars (TAGs), it is examined whether the restrictions of linearity and nondeletion on monadic CFTGs are necessary to generate the same class of languages.
FEC-Based Multiple Description Coding for Heterogeneous Client Bandwidths
Authors: Longshe Huo, Wen Gao, Qingming Huang, Ying Cai
Venue: Proceedings of the Third International Conference on Image and Graphics (2004)

We consider applying the FEC-based multiple description coding method for multicasting a source to a set of clients with heterogeneous access bandwidths. In the scenario where different clients access the server via separate links, we propose a procedure which refines the already computed optimal solutions for other bandwidths, using different packet lengths. Compared to the scheme that computes an optimal solution individually for each bandwidth, this procedure is quite faster and has comparable performance. In another scenario where many clients share a bottleneck link, we extend our embedded packetization framework to be available in more than two bandwidths, and propose a fast heuristic algorithm which can achieve very good performance tradeoff among all clients.
Automatic March Tests Generation for Static and Dynamic Faults in SRAMs
Authors: A. Benso, A. Bosio, S. Di Carlo, G. Di Natale, P. Prinetto
Venue: Proceedings of the 10th IEEE European Symposium on Test (2005)

New memory production modern technologies introduce new classes of faults usually referred to as Dynamic Memory Faults. Although some hand-made March Tests to deal with these new faults have been published, the problem of automatically generate March Tests for Dynamic Faults has still to be addressed. In this paper we propose a new approach to automatically generate March Tests with minimal length for both Static and Dynamic Faults. The proposed approach resorts to a formal model to represent faulty behaviors in a memory and to simplify the generation of the corresponding tests.
Mapping Security: The Corporate Security Sourcebook for Today's Global Economy
Authors: Tom Patterson, Scott Gleeson Blue
Venue:  (2004)

The Definitive Guide to Effective Security in Complex Global MarketsCompanies are global today and have complex security supply chains, out-sourced operations, and customer relationships that span the world. Today, more than ever, companies must protect themselves against unprecedented threats, understand and adhere to a global mosaic of regulations, and leverage security to enable today's business realities. In Mapping Security, global security expert Tom Patterson shows how to meet these challenges by presenting security best practices, rules, and customs for virtually every country where you do business.Writing for executives, business managers, security professionals, and consultants, Patterson offers an exceptionally thorough and authoritative briefing on today's global security realities. Using real-world examples, he shows how to change your approach to security as you move more deeply into global markets: how to resolve contradictions among the complex rules and customs you'll have to follow and how to customize security solutions for every market. Along the way, he introduces the Mapping Security Index (MSI), a powerful new metric for rapidly quantifying security risk associated with 30 key markets. Coverage includes How technology, mass globalization, and stricter accountability are forcing security to the core of the enterprise Six proven keys to defining and implementing global security strategies that work within today's budget realities Detailed country-by-country drill downs on security in Europe, the Middle East and Africa, the Americas, and the Asia-Pacific region Practical advice on what to do when laws collide Quantifying the security posture and associated risks of potential cross-border partners "On-the-ground" help: Indispensable local security resources
A framework for spatio-temporal query processing over wireless sensor networks
Authors: Alexandru Coman, Mario A. Nascimento, Jörg Sander
Venue: Proceeedings of the 1st international workshop on Data management for sensor networks: in conjunction with VLDB 2004 (2004)

Wireless sensor networks consist of nodes with the ability to measure, store, and process data, as well as to communicate wirelessly with nodes located in their wireless range. Users can issue queries over the network, e.g., retrieve information from nodes within a specified region, in applications such as environmental monitoring. Since the sensors have typically only a limited power supply, energy-efficient processing of the queries over the network is an important issue. In this paper, we introduce a general framework for distributed processing of spatio-temporal queries in a sensor network that has two main phases: (1) routing the query to the spatial area specified in the query; (2) collecting and processing the information from the nodes relevant to the query. Within this framework, different algorithms can be designed independently for each of the two phases. We also propose novel algorithms for this framework, one for the first phase and two for the second phase. In an extensive experimental evaluation we study the performance of these algorithms in terms of energy consumption, under varying conditions. The results allow us to recommend the most energy efficient solution, given a network and a spatiotemporal query.
Reducing data stream sliding windows by cyclic tree-like histograms
Authors: Francesco Buccafurri, Gianluca Lax
Venue: Proceedings of the 8th European Conference on Principles and Practice of Knowledge Discovery in Databases (2004)

Data reduction is a basic step in a KDD process useful for delivering to successive stages more concise and meaningful data. When mining is applied to data streams, that are continuous data flows, the issue of suitably reducing them is highly interesting, in order to arrange effective approaches requiring multiple scans on data, that, in such a way, may be performed over one or more reduced sliding windows. A class of queries, whose importance in the context of KDD is widely accepted, corresponds to sum range queries. In this paper we propose a histogram-based technique for reducing sliding windows supporting approximate arbitrary (i.e., non biased) sum range queries. The histogram, based on a hierarchical structure (opposed to the flat structure of traditional ones), results suitable for directly supporting hierarchical queries, and, thus, drill-down and roll-up operations. In addition, the structure well supports sliding window shifting and quick query answering (both these operations are loarithmic in the sliding window size). Experimental analysis shows the superiority of our method in terms of accuracy w.r.t. the state-of-the-art approaches in the context of histogram-based sliding window reduction techniques.
A Robust Interference Model for Wireless Ad-Hoc Networks
Authors: Pascal von Rickenbach, Stefan Schmid, Roger Wattenhofer, Aaron Zollinger
Venue: Proceedings of the 19th IEEE International Parallel and Distributed Processing Symposium (IPDPS'05) - Workshop 12 - Volume 13 (2005)

Among the foremost goals of topology control in wireless ad-hoc networks is interference reduction. This paper presents a receiver-centric interference model featuring two main advantages over previous work. First, it reflects the fact that interference occurs at the intended receiver of a message. Second, the presented interference measure is robust with respect to addition or removal of single network nodes. Regarding both of these aspects our model intuitively corresponds to the behavior of interference in reality. Based on this interference model, we show that currently known topology control algorithms poorly reduce interference. Motivated by the observation that already onedimensional network instances display the intricacy of the considered problem, we continue to focus on the so-called highway model. Setting out to analyze the special case of the exponential node chain, we eventually describe an algorithm guaranteeing to achieve a ^4 \sqrt \vartriangle -approximation of the optimal connectivity-preserving topology in the general highway model.
On the Comprehension of Security Risk Scenarios
Authors: Ida Hogganvik, Ketil Stolen
Venue: Proceedings of the 13th International Workshop on Program Comprehension (2005)

Methods for security risk analysis are often based on structured brainstorming (e.g. what calls HazOp). A structured brainstorming gathers a group of different system experts and the idea is that they will find more risks as a team than one-by-one. The CORAS modelling language has been designed to support the brainstorming process and to document security risk scenarios identified during these sessions. The language is graphical, based upon the Unified Modelling Language (UML), and is recommended by OMG. This paper reports the results from two empirical experiments concerning the CORAS language. Our results show (1) many security risk analysis terms are used in the daily language and therefore well understood, but the more abstract or less frequently used terms can be a possible source for misunderstandings in a security analysis, and (2) the language's graphical icons make diagram "navigation" faster, but the diagrams are not necessarily understood more correctly than those without graphical icons.
Multivariate integration in weighted Hilbert spaces based on Walsh functions and weighted Sobolev spaces
Authors: Josef Dick, Friedrich Pillichshammer
Venue: Journal of Complexity (2005)

We introduce a weighted reproducing kernel Hilbert space which is based on Walsh functions. The worst-case error for integration in this space is studied, especially with regard to (t, m, s)-nets. It is found that there exists a digital (t, m, s)-net, which achieves a strong tractability worst-case error bound under certain condition on the weights.We also investigate the worst-case error of integration in weighted Sobolev spaces. As the main tool we define a digital shift invariant kernel associated to the kernel of the weighted Sobolev space. This allows us to study the mean square worst-case error of randomly digitally shifted digital (t, m, s)- nets. As this digital shift invariant kernel is almost the same as the kernel for the Hilbert space based on Walsh functions, we can derive results for the weighted Sobolev space based on the analysis of the Walsh function space. We show that there exists a (t, m, s)-net which achieves the best possible convergence order for integration in weighted Sobolev spaces and are strongly tractable under the same condition on the weights as for lattice rules.
Computer art: a personal recollection
Authors: Frieder Nake
Venue: Proceedings of the 5th conference on Creativity cognition (2005)

The story of some early computer art drawings in 1965 is told. It is a story of randomness. Computer art is viewed here as the programming of classes of aesthetic objects. In the mid 1960s, information aesthetics was a powerful and radical theory that had some influence on constructive and concrete forms of art in Europe. A connection is drawn to computer supported works by A. Michael Noll in the US, and Georg Nees in Germany. "Experiment and tendency" is identified as an important principle still valid today. The concept of the algorithmic sign appears at the horizon. Digital media are claimed to be explorations of algorithmic signs.
An adaptative mechanism for communicating with mobile objects
Authors: Denis Caromel, Fabrice Huet
Venue: Proceedings of the 1st French-speaking conference on Mobility and ubiquity computing (2004)

As middlewares are more and more spanning over larger networks, towards world-wide grid computing, communicating with mobile objects in a scalable and reliable manner becomes an important and difficult issue. This paper proposes a parametric protocol for such communications. Based on Time To Live (TTL) forwarders, and Time To Update (TTU) mobile objects, it allows to get the best of those two well-known techniques (forwarders, servers). As a parametric protocol, it can be adapted to various network conditions.
GMRES Convergence Analysis for a Convection-Diffusion Model Problem
Authors: J. Liesen, Z. Strakos
Venue: SIAM Journal on Scientific Computing (2005)

When GMRES [Y. Saad and M. H. Schultz, SIAM J. Sci. Statist. Comput.}, 7 (1986), pp. 856--869] is applied to streamline upwind Petrov--Galerkin (SUPG) discretized convection-diffusion problems, it typically exhibits an initial period of slow convergence followed by a faster decrease of the residual norm. Several approaches were made to understand this behavior. However, the existing analyses are solely based on the matrix of the discretized system and they do not take into account any influence of the right-hand side (determined by the boundary conditions and/or source term in the PDE). Therefore they cannot explain the length of the initial period of slow convergence which is right-hand side dependent.We concentrate on a frequently used model problem with Dirichlet boundary conditions and with a constant velocity field parallel to one of the axes. Instead of the eigendecomposition of the system matrix, which is ill conditioned, we use its orthogonal transformation into a block-diagonal matrix with nonsymmetric tridiagonal Toeplitz blocks and offer an explanation of GMRES convergence. We show how the initial period of slow convergence is related to the boundary conditions and address the question why the convergence in the second stage accelerates.
Communities Collaborating to Bridge the Digital Divide: The Tribal Virtual Network
Authors: Maria Williams, Vernon Lujan, Ron Solimon, Lorene Willis, Tom Kennedy, Kevin Shendo, Julie Frendle, Barbara Tracy, Sam Catanach, Jeffery Edaakie, Arlan Sando, Jacqui Velarde
Venue: Proceedings of the 2003 ACM/IEEE conference on Supercomputing (2003)

The Digital Divide has become a catch phrase and political banner that defines the divide between the "have and have-nots" of internet-based technologies. Many rural and Native American communities often have little or no access to basic Internet service, let alone high or even low bandwidth connectivity. A consortium of five tribal museums, culture centers and education programs in New Mexico have entered into a partnership to develop and implement a project that provides a solution to rural communities that lack infrastructure and connectivity. The five sites (the Pueblos of Jemez, Pojoaque, Zuni, the Indian Pueblo Culture Center, and the Jicarilla Apache Nation), located throughout northern and north central New Mexico, are using Access Grid technology that uses a low bandwidth solution (less than 1.5 megabits). The Tribal Virtual Network or TVN has been funded by a grant from the Department of Commerce. With their support and the support of the University of New Mexico's Arts of the Americas Institute the Tribal Virtual Network is exploring different ways to use AG technology to benefit their communities. Some of the initiatives include accessing long distance education and training, facilitating communication and virtual meetings, developing innovative exchange programs, and participating with other AG-enabled platforms.
Maximum-lifetime routing algorithms for networks with omnidirectional and directional antennas
Authors: Ariel Orda, Ben-Ami Yassour
Venue: Proceedings of the 6th ACM international symposium on Mobile ad hoc networking and computing (2005)

A major problem in wireless networks is how to route either broadcast, unicast or multicast traffic so as to maximize the lifetime, i.e., the time until the battery of a transmitting node drains out. Focusing on the fundamental single-session problem, our solution approach is based on the employment of multi-topology routing schemes. Such a scheme consists of a set of routing topologies, which are employed sequentially, for some prescribed duration times.First, we consider the standard wireless environment of multiple recipients, which correspond to omnidirectional antennas. For the cases of either single-topology schemes or unicast sessions, we establish optimal solutions of polynomial complexity. For the general (multi-topology) cases of broadcast and multicast, which are NP-hard, we derive a novel heuristic scheme, and demonstrate its efficiency by way of simulations.We then consider an alternative, single-recipient wireless environment, which corresponds to the important case of directional antennas. While the employment of directional antennas is known to posses significant advantages over the traditional omnidirectional transmission, the problem of lifetime maximization under this environment has received only limited attention.We demonstrate that the change from the traditional (multiple-recipients) environment to the single-recipient environment is of major significance in terms of computational complexity and produces an interesting twist of difficulty: namely, for the standard model, the single-topology broadcast problem is computationally solvable and the multi-topology problem is NP-hard, while the opposite holds for the single-recipient model. Finally, we discuss the extension of our results to the case of multiple sessions.
Fundamental Limits in the Rendering of Virtual Haptic Textures
Authors: Gianni Campion, Vincent Hayward
Venue: Proceedings of the First Joint Eurohaptics Conference and Symposium on Haptic Interfaces for Virtual Environment and Teleoperator Systems (2005)

We discuss the properties of force-feedback haptic simulation systems that fundamentally limit the re-creation of periodic gratings, and hence, of any texture. These include sampling rate, device resolution, and structural dynamics. Basic sampling limitations are analyzed in terms of the Nyquist and the Courant conditions. The analysis proposes that noise due to sampling and other sources injected in the system may prevent it to achieve acceptable performance in most operating conditions, unless special precautions such as the use of a reconstruction filter, make the closed-loop more robust to noise. The structural response of a PHANTOM 1.0A device was such that no such filter could be found, and the system introduced heavy distortion in gratings as coarse as 10 mm. The Pantograph Mark-II device having more favorable structural properties could reliably create gratings between 1 and 10 mm.
Recognition of Partially Occluded Objects Using Perfect Hashing: An Efficient and Robust Approach
Authors: R. Dinesh, D. S. Guru
Venue: Proceedings of the 2nd Canadian conference on Computer and Robot Vision (2005)

This paper presents a novel method for recognizing partially occluded objects. The proposed method uses corner points and their spatial relationship perceived through the application of Triangular Spatial Relationship (TSR) by considering three consecutive corner points at a time. The perceived TSR among corner points are used to create a model object-base using the technique of perfect hashing. The matched sequence is preserved in a two-dimensional matrix called status matrix. Experimental results, on real images of varying complexity of a reasonably large database of objects have established the robustness of the method.
Reformulation descent applied to circle packing problems
Authors: Nenad Mladenović, Frank Plastria, Dragan Urošević
Venue: Computers and Operations Research (2005)

Several years ago classical Euclidean geometry problems of densest packing of circles in the plane have been formulated as nonconvex optimization problems, allowing to find heuristic solutions by using any available NLP solver. In this paper we try to improve this procedure. The faster NLP solvers use first order information only, so stop in a stationary point. A simple switch from Cartesian coordinates to polar or vice versa, may destroy this stationarity and allow the solver to descend further. Such formulation switches may of course be iterated. For densest packing of equal circles into a unit circle, this simple feature turns out to yield results close to the best known, while beating second order methods by a time-factor well over 100.This technique is formalized as a general reformulation descent (RD) heuristic, which iterates among several formulations of the same problem until local searches obtain no further improvement. We also briefly discuss how RD might be used within other metaheuristic schemes.
SOAT: a semi-automatic domain ontology acquisition tool from Chinese corpus
Authors: Shih-Hung WU, Wen-Lian HSU
Venue: Proceedings of the 19th international conference on Computational linguistics - Volume 2 (2002)

In this paper, we focus on the domain ontology acquisition from Chinese corpus by extracting rules designed for Chinese phrases. These rules are noun sequences with part-of-speech tags. Experiments show that this process can construct domain ontology prototypes efficiently and effectively.