Interrelation of the Cyclic and Weight Structure of Codes over <Emphasis Type="Italic">GF</Emphasis>(<Emphasis Type="Italic">q</Emphasis>) and Proportionality Classes

To determine the weight structure of cyclic codes, we establish an interrelation of the cyclic structure of a code and classes of proportional elements.__________Translated from Problemy Peredachi Informatsii, No. 2, 2005, pp. 68–71.Original Russian Text Copyright © 2005 by Mullayeva.     

Design of Digital State <Emphasis Type="Italic">H</Emphasis><Subscript>∞</Subscript>-Controllers of the MIMO Systems with Prescribed Precision

For the linear MIMO plants subject to polyharmonic perturbations, a method of designing digital state controllers was developed with regard for the requirements on limitedness of the control actions in the stable state as well as on limitedness of the controlled variables. A notion of radius of the stable state of a closed-loop system was introduced, and the problem of using the full state vector to design a discrete controller providing the desired radius was formulated. Its necessary and sufficient solvability conditions were obtained using the procedure of H _∞-optimization by selecting the weight matrices of the discrete Lur’e-Riccati equation.__________Translated from Avtomatika i Telemekhanika, No. 8, 2005, pp. 46–51.Original Russian Text Copyright © 2005 by Chestnov.     

Extension of the <Emphasis Type="Italic">S</Emphasis>-procedure and analysis of the multidimensional control systems using linear matrix inequalities

Consideration was given to a generalization of the so-called S-procedure in the problem of sign-definiteness of the quadratic form under quadratic constraints. Application of the algebraic criterion obtained to analysis of the multidimensional control system was discussed. The results were formulated in terms of solvability of the linear matrix inequalities.This work was supported by the Russian Foundation for Basic Research, project no. 04-01-00391a, and the Complex Program of the Presidium of the Russian Academy of Sciences, project no. 19-1.5.Translated from Avtomatika i Telemekhanika, No. 1, 2005, pp. 37–48.Original Russian Text Copyright © 2005 by Rapoport.     

Extensions of fuzzy hyperideals in <Emphasis Type="Italic">H</Emphasis><Subscript><Emphasis Type="Italic">V</Emphasis></Subscript>-semigroups

The object of the present paper is the investigation and study of (fuzzy) hyperideals in H _v - semigroups. Regular equivalence relations play in H _v - semigroup theory a role analogous to congruences in semigroup theory, so we introduce fuzzy regular equivalence relations on H _v -semigroups and then we study fuzzy Rees regular relations on H _v -semigroups. Using this ideas, we establish a relation between fuzzy hyperideal of an H _v -semigroup H and fuzzy hyperideal of a quotient H _v -semigroup of H. Some characterizations of them are then shown.      

Electrical properties and crystallization behavior of Sb<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Se<Subscript>100−<Emphasis Type="Italic">x</Emphasis></Subscript> thin films

The structural transformation and transformation kinetics of Sb _x Se_100−x films (60 ≤ x ≤ 70) were studied to investigate the feasibility of applying Sb _x Se_100−x alloys in phase-change nonvolatile memories. The temperature-dependent van der Pauw measurements, Hall measurements, X-ray diffraction and a static tester were used to investigate the electrical properties and crystallization behavior of the Sb _x Se_100−x films. The sheet resistance difference between amorphous and crystalline state was higher than 10⁴ Ω per square According to Hall measurement, Sb _x Se_100−x films have p-type conduction and the Hall mobility and carrier concentration increases with the increase in Sb content. The crystalline structure of the metastable phase of Sb _x Se_100−x alloys, which plays a major roll in fast crystallization, is similar to that of Sb₂Te (rhombohedral structure). The transition temperature, sheet resistance and activation energy for transformation decrease as the amount of Sb increases in the Sb _x Se_100−x film. Applying the Kissinger method, the activation energies for crystallization were in the range from 1.90 ± 0.15 to 4.16 ± 0.28 eV. The desired crystallization speed can be obtained by a systematic change of the composition owing to the variation of the activation barrier with stoichiometry.     

Minimized embedding of arbitrary hamiltonian graphs in fault-tolerant graph and reconfiguration at faults. II. Grids and <Emphasis Type="Italic">k</Emphasis>-fault-tolerance

Optimal algorithms to construct 1-fault-tolerant structures were presented with examples of simple and diagonal grids and torus based on algorithm A2 discussed in the first part of the paper. The general procedure of constructing the k-fault-tolerant structures was presented first for a simple cycle and then for more involved grid graphs. Algorithms for reconfiguration after failure were described. For the 1-fault-tolerant structures, these algorithms are realized as a simple table of automorphisms of the fault-tolerant graph. For the case of k-fault-tolerance, correct reconfiguration requires symmetrization of the reduced graph after the ith failure by elimination of the redundant connections introduced to improve fault-tolerance from i - 1 to i when constructin the k-fault-tolerant system graph.Translated from Avtomatika i Telemekhanika, No. 2, 2005, pp. 175–189.Original Russian Text Copyright © 2005 by Karavai.     

View selection for <Emphasis Type="Italic">real</Emphasis> conjunctive queries

Given a query workload, a database and a set of constraints, the view-selection problem is to select views to materialize so that the constraints are satisfied and the views can be used to compute the queries in the workload efficiently. A typical constraint, which we consider in the present work, is to require that the views can be stored in a given amount of disk space. Depending on features of SQL queries (e.g., the DISTINCT keyword) and on whether the database relations on which the queries are applied are sets or bags, the queries may be computed under set semantics, bag-set semantics, or bag semantics. In this paper we study the complexity of the view-selection problem for conjunctive queries and views under these semantics. We show that bag semantics is the “easiest to handle” (we show that in this case the decision version of view selection is in NP), whereas under set and bag-set semantics we assume further restrictions on the query workload (we only allow queries without self-joins in the workload) to achieve the same complexity. Moreover, while under bag and bag-set semantics filtering views (i.e., subgoals that can be dropped from the rewriting without impacting equivalence to the query) are practically not needed, under set semantics filtering views can reduce significantly the query-evaluation costs. We show that under set semantics the decision version of the view-selection problem remains in NP only if filtering views are not allowed in the rewritings. Finally, we investigate whether the cgalg algorithm for view selection introduced in Chirkova and Genesereth (Linearly bounded reformulations of conjunctive databases, pp. 987–1001, 2000) is suitable in our setting. We prove that this algorithm is sound for all cases we examine here, and that it is complete under bag semantics for workloads of arbitrary conjunctive queries and under bag-set semantics for workloads of conjunctive queries without self-joins. Rada Chirkova’s work on this material has been supported by the National Science Foundation under Grant No. 0307072. The project is co-funded by the European Social Fund (75%) and National Resources (25%)- Operational Program for Educational and Vocational Training II (EPEAEK II) and particularly the program PYTHAGORAS. A preliminary version of this paper appears in F. Afrati, R. Chirkova, M. Gergatsoulis, V. Pavlaki. Designing Views to Efficiently Answer Real SQL Queries. In Proc. of SARA 2005, LNAI Vol. 3607, pages 332-346, Springer-Verlag, 2005.     

Particle swarm optimization-based fixed-structure <Emphasis Type="Italic">ℋ</Emphasis><Subscript>∞</Subscript> control design

In this paper, a new robust fixed-structure ℋ _∞ controller design based on the Particle Swarm Optimization (PSO) technique is proposed. The optimization-based structured synthesis problem is formulated and solved by a constrained PSO algorithm. In the proposed approach, the ℋ _∞ controller’s structure is selectable. PI and PID controller structures are especially adopted. The case study of an electrical DC drive benchmark is adopted to illustrate the efficiency and viability of the proposed control approach. A comparison to another similar evolutionary algorithm, such as Genetic Algorithm Optimization (GAO), shows the superiority of the PSO-based method to solve the formulated optimization problem. Simulations and experimental results show the advantages of simple structure, lower order and robustness of the proposed controller.     

An Augmented Lagrangian Method for <Emphasis Type="Italic">TV</Emphasis><Subscript><Emphasis Type="Italic">g</Emphasis></Subscript>+<Emphasis Type="Italic">L</Emphasis><Superscript>1</Superscript>-norm Minimization

In this paper, the minimization of a weighted total variation regularization term (denoted TV _g ) with L ¹ norm as the data fidelity term is addressed using the Uzawa block relaxation method. The unconstrained minimization problem is transformed into a saddle-point problem by introducing a suitable auxiliary unknown. Applying a Uzawa block relaxation method to the corresponding augmented Lagrangian functional, we obtain a new numerical algorithm in which the main unknown is computed using Chambolle projection algorithm. The auxiliary unknown is computed explicitly. Numerical experiments show the availability of our algorithm for salt and pepper noise removal or shape retrieval and also its robustness against the choice of the penalty parameter. This last property is useful to attain the convergence in a reduced number of iterations leading to efficient numerical schemes. The specific role of the function g in TV _g is also investigated and we highlight the fact that an appropriate choice leads to a significant improvement of the denoising results. Using this property, we propose a whole algorithm for salt and pepper noise removal (denoted UBR-EDGE) that is able to handle high noise levels at a low computational cost. Shape retrieval and geometric filtering are also investigated by taking into account the geometric properties of the model.     

Some light-traffic and heavy-traffic results for the <Emphasis Type="Italic">GI</Emphasis>/<Emphasis Type="Italic">G</Emphasis>/<Emphasis Type="Italic">n</Emphasis>/0 queue using the <Emphasis Type="Italic">GM Heuristic</Emphasis>

In this paper we carry out both light-traffic and heavy-traffic analyses for the calculation of steady-state loss probabilities in the general multi-server queuing loss system, the GI/G/n/0 queue. The analysis makes use of a heuristic approach called the GM Heuristic, for which a detailed analysis in normal traffic has previously been published. Sufficient conditions are given for the GM Heuristic to be asymptotically exact in light traffic. The heuristic is also shown to be asymptotically exact in heavy-traffic when the number of servers n tends to infinity. These results are illustrated numerically using two-phase Coxian distributions for both the inter-arrival time and service time.     

The <Emphasis Type="Italic">POINT</Emphasis> approach to represent <Emphasis Type="Italic">now</Emphasis> in bitemporal databases

Most modern database applications involve a significant amount of time dependent data and a significant portion of this data is now-relative. Now-relative data are a natural and meaningful part of every temporal database as well as being the focus of most queries. Previous studies indicate that the choice of the representation of now significantly influences the efficiency of accessing bitemporal data. In this paper we propose and experimentally evaluate a novel approach to represent now that we termed the POINT approach, in which now-relative facts are represented as points on the transaction-time and/or valid-time line. Furthermore, in the POINT approach we propose a logical query transformation that relies on the above representation and on the geometry features of spatial access methods. Such a logical query transformation enables off-the-shelf spatial indexes to be used. We empirically prove that the POINT approach is efficient on now-relative bitemporal data, outperforming the maximum timestamp approach that has been proven to the best approach to now-relative data in the literature, independently of the indexing methodology (B ⁺- tree vs R ^*- tree) being used. Specifically, if spatial indexing is used, the POINT approach outperforms the maximum timestamp approach to the extent of factor more than 10, both in number of disk accesses and CPU usage.     

3D virtual mosaics: <Emphasis Type="Italic">Opus Palladium</Emphasis> and <Emphasis Type="Italic">mixed</Emphasis> styles

One of the oldest art forms, mosaics are built by careful selection and placement of small pieces called tiles. Although 2D mosaics have attracted attention in computer graphics research, 3D virtual mosaic sculptures are less common. In this work, we present a method to simulate mosaic sculptures using tiles with irregular shapes, a method known by mosaicists as Opus Palladium, or simply “crazy paving,” due to the inherent freedom of mixing the tiles. In order to add expressiveness and emphasize some features, artists distribute the tiles following a high-level design over the shape. We use Voronoi polygons to represent the tiles computed from a distribution of points on the surface of the 3D object. We also address the simulation of mixed mosaics, where both irregular and squared-shape tiles are used on the same object. Previous works on such surface mosaics have used only square-shaped tiles, with fixed or variable size. Special mosaic-like effects are obtained with the help from texture maps, which control the high-level design of the tile distribution.     

On one transformation of Steiner quadruple systems <Emphasis Type="Italic">S</Emphasis>(<Emphasis Type="Italic">υ</Emphasis>, 4, 3)

A transformation of Steiner quadruple systems S(υ, 4, 3) is introduced. For a given system, it allows to construct new systems of the same order, which can be nonisomorphic to the given one. The structure of Steiner systems S(υ, 4, 3) is considered. There are two different types of such systems, namely, induced and singular systems. Induced systems of 2-rank r can be constructed by the introduced transformation of Steiner systems of 2-rank r − 1 or less. A sufficient condition for a Steiner system S(υ, 4, 3) to be induced is obtained.     

Robust <Emphasis Type="Italic">H</Emphasis><Subscript>∞</Subscript> fuzzy control for discrete-time nonlinear systems

This paper studies the problem of robust H _∞ control for discrete-time nonlinear systems presented as Takagi—Sugeno’s fuzzy models. The generalized non-parallel distributed compensation (non-PDC) law and non-quadratic Lyapunov function is constructed by the proposed homogeneouspolynomially basis-dependent matrix function (HPB-MF for abbreviation). Based on the generalized non-PDC law and non-quadratic Lyapunov function, some linear matrix inequalities (LMIs) are obtained by exploiting the possible combinations of the basis functions. These LMIs ensure the asymptotic stability of the closed-loop system and guarantee a norm bound constraint on disturbance attenuation. In addition, it is shown that the LMIs become less conservative as the degree of HPB-MF increases. The merit of the methods presented in this paper lies in their less conservatism than other methods, as shown by a numerical example borrowed from the literature.     

Three-dimensional analysis of Marangoni flow and radial segregation in Ge<Subscript><Emphasis Type="Italic">x</Emphasis></Subscript>Si<Subscript>1-<Emphasis Type="Italic">x</Emphasis></Subscript> melt with Czochralski configuration

In order to examine the flow field and the radial segregation of silicon (Si) in a Ge _x Si_1-x melt with an idealized Czochralski (Cz) configuration, we conducted a series of unsteady three-dimensional (3-D) numerical simulations under zero-gravity conditions. The effect of convection driven by surface tension on the free surface of the melt was included in the model, by considering thermal, as well as solutal Marangoni convection. The concentration and flow fields at several stages during crystal growth are presented for several temperature differences, driving the Marangoni convection. The simulation results indicate that the flow and concentration fields are axisymmetric for Ma _T < 625 and become oscillatory and 3-D for higher values. It was found that the maximum Si concentration difference at the growth interface decreases as thermal Marangoni number increases due to higher flow velocities in the vicinity of the interface. However, temporal fluctuations of Si concentration at the interface increase at higher thermal Marangoni numbers. The effects of aspect ratio (A _r) were also considered in the model. It was found that the aspect ratio of the melt in the crucible has a prominent influence on the flow pattern in the melt which, in turn, effects the Si concentration at the growth interface.     

Fast running algorithm for discrete <Emphasis Type="Italic">W</Emphasis> transform

A fast algorithm for computing the running type-II discrete W transform (DWT-II) is proposed. The algorithm is based on a recursive relationship between three subsequent local DWT-II spectra. The computational complexity of the algorithm is compared with that of known fast and running DWT-II algorithms. Fast inverse algorithms for signal processing in the domain of the running DWT-II are also proposed. Vitaly Kober obtained his MS degree in Applied Mathematics from the Air-Space University of Samara (Russia) in 1984, and his PhD degree in 1992 and Doctor of Sciences degree in 2004 in Image Processing from the Institute of Information Transmission Problems, Russian Academy of Sciences. Now he is a titular researcher at the Centro de Investigacion Cientifica y de Educacion Superior de Ensenada (Cicese), Mexico. His research interests include signal and image processing, pattern recognition. Iosif A. Ovseevich graduated from the Moscow Electrotechnical Institute of Telecommunications. Received candidate’s degree in 1953 and doctoral degree in information theory in 1972. At present he is Emeritus Professor at the Institute of Information Transmission Problems of the Russian Academy of Sciences. His research interests include information theory, signal processing, and expert systems. He is a Member of IEEE, Popov Radio Society.     

Image Compression and Reconstruction Using pi<Subscript><Emphasis Type="Italic">t</Emphasis></Subscript>-Sigma Neural Networks

A high-order feedforward neural architecture, called pi _t -sigma (π _t σ) neural network, is proposed for lossy digital image compression and reconstruction problems. The π _t σ network architecture is composed of an input layer, a single hidden layer, and an output layer. The hidden layer is composed of classical additive neurons, whereas the output layer is composed of translated multiplicative neurons (π _t -neurons). A two-stage learning algorithm is proposed to adjust the parameters of the π _t σ network: first, a genetic algorithm (GA) is used to avoid premature convergence to poor local minima; in the second stage, a conjugate gradient method is used to fine-tune the solution found by GA. Experiments using the Standard Image Database and infrared satellite images show that the proposed π _t σ network performs better than classical multilayer perceptron, improving the reconstruction precision (measured by the mean squared error) in about 56%, on average.     

Classification of optimal (<Emphasis Type="Italic">v</Emphasis>, 4, 1) binary cyclically permutable constant-weight codes and cyclic 2-(<Emphasis Type="Italic">v</Emphasis>, 4, 1) designs with <Emphasis Type="Italic">v</Emphasis> ≤ 76

We classify up to isomorphism optimal (v, 4, 1) binary cyclically permutable constantweight (CPCW) codes with v ≤ 76 and cyclic 2-(73, 4, 1) and 2-(76, 4, 1) designs. There is a one-to-one correspondence between optimal (v, 4, 1) CPCW codes, optimal cyclic binary constant-weight codes with weight 4 and minimum distance 6, (v, 4; ⌎(v − 1)/12⌏) difference packings, and optimal (v, 4, 1) optical orthogonal codes. Therefore, the classification of CPCW codes holds for them too. Perfect (v, 4, 1) CPCWcodes are equivalent to (v, 4, 1) cyclic difference families, and thus (73, 4, 1) cyclic difference families are classified too.