Wyniki wyszukiwania - Biblioteka Nauki

1

Remarks on an inverse modelling of welding processes

100%

Ranatowski E.

Advances in Materials Science

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2005

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tom Vol. 5, nr 1-3

21-31

EN

At the beginning of this work a short characteristic of the methodology of modelling rules of welding process is provided. The relation between both the intensive and extensive parameters are mainly discussed. Additionally, the theoretical bases of modelling of welding processes are presented. In further on the bases of modelling of inverse heat conduction problem is talked over. It bases on the strategy of solving inverse problems [2], it employs the hybrid an analytic - numerical method for analysis these questions. Finally, the appropriate algorithms in moving and stationary systems are established which can be directly applied to solving inverse problem.

2

Performance Evaluation of Preemption Algorithms in MPLS Networks

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Kaczmarek S. , Nowak K.

International Journal of Electronics and Telecommunications

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2011

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tom Vol. 57, No. 2

169-175

EN

Preemption is a traffic engineering technique in Multiprotocol Switching Network that enables creation of high priority paths when there is not enough free bandwidth left on the route. Challenging part of any preemption method is to select the best set of paths for removal. Several heuristic methods are available but no wider comparison had been published before. In this paper, we discusses the dilemmas in implementing preemption methods are presented the simulation studyof well known existing algorithms. Based on the results, we provide recommendations for deployment of preemption for the two most common evaluation criteria: number of preemption and preempted bandwidth.

3

A method to improve design reliability using optimal Latin hypercube sampling

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Stocki R.

Computer Assisted Mechanics and Engineering Sciences

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2005

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tom Vol. 12, No. 4

393-411

EN

In the paper an algorithm for design reliability improvement is proposed. Its key part consists in the computation of the correlations between constraint functions and design variables which are subsequently used to find the new design iteration. It is shown that the optimal Latin hypercube (OLH) sampling provides an extremely efficient technique for assessing the values of correlation coefficients. Since finding the large OLH designs is not a trivial task, a study on the OLH generation algorithms was performed. Two algorithms were found to be particularly effective, namely, the columnwise-pairwise algorithm and the genetic algorithm. The presented strategy proves to be especially useful when alternative gradient-based methods cannot be used, which is often the case for computationally expensive problems involving noisy and highly non-linear responses. The method is best suited for problems where the probability of failure for the initial design is large and the main interest is to find a more reliable design rather than the optimal one in the sense of reliability-based optimization. The method is illustrated with two numerical examples. One model example and one concerning the problem of thin-walled beam crash.

4

The recommendation algorithm for an online art gallery

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Karwowski W. , Sosnowska J. , Rusek M.

Information Systems in Management

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2018

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tom Vol. 7, No. 2

108--119

EN

The paper discusses the need for recommendations and the basic recommendation systems and algorithms. In the second part the design and implementation of the recommender system for online art gallery (photos, drawings, and paintings) is presented. The designed customized recommendation algorithm is based on collaborative filtering technique using the similarity between objects, improved by information from user profile. At the end conclusions of performed algorithm are formulated.

5

Algorytmizacja przestrzeni internetowej

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Szews P. , Uniwersytet Łódzki W. F. , Przemysław Szews – doktorant w Katedrze Dziennikarstwa i Komunikacji Społecznej na Wydziale Filologicznym Uniwersytetu Łódzkiego. Przygotowuje rozprawę doktorską na temat wizualizowania informacji w dziennikarstwie. Badacz nowych mediów i dziennikarstwa sportowego z. i. p. K. D. S. L. N. F. N. U. Ł. z. d. n. w. o. n. h. , p.szews@uni.lodz.pl

Acta Universitatis Lodziensis. Folia Litteraria Polonica

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2015

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tom 28

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nr 2

EN

The article tackles the problem of the existence of algorithms in selected services and the Internet websites. The interfacing of media is the starting point for this discourse, aimed at presenting the processes of automatisation in information distribution, the individualisation of messages, and profiling in websites. The threats resulting from dynamically developing enterprises aimed at providing the website user with artificial intelligence – in terms of both social networks and mobile applications – are explicated in detail. The examples presented in the article refer to Internet recommendation systems, e-mail applications, voice assistants, and mechanisms responsible for the functioning of social networks. Speculations on the algorithms omnipresent on the net lead us to reflect on how the journalist’s profession will be redefined in the future, since it seems that the role of the journalist will be to moderate discussion and select the themes to be discussed; it is quite likely, though, that the themes selected will be compiled by specialised software.

6

Verification and Parameter Synthesis for Real-Time Programs using Refinement of Trace Abstraction

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Cassez F. , Jensen P. G. , Guldstrand Larsen K.

Fundamenta Informaticae

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2021

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tom Vol. 178, nr 1/2

31--57

EN

We address the safety verification and synthesis problems for real-time systems. We introduce real-time programs that are made of instructions that can perform assignments to discrete and real-valued variables. They are general enough to capture interesting classes of timed systems such as timed automata, stopwatch automata, time(d) Petri nets and hybrid automata. We propose a semi-algorithm using refinement of trace abstractions to solve both the reachability verification problem and the parameter synthesis problem for real-time programs. All of the algorithms proposed have been implemented and we have conducted a series of experiments, comparing the performance of our new approach to state-of-the-art tools in classical reachability, robustness analysis and parameter synthesis for timed systems. We show that our new method provides solutions to problems which are unsolvable by the current state-of-the-art tools.

7

Singly-Thermostated Ergodicity in Gibbs’ Canonical Ensemble and the 2016 Ian Snook Prize Award

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Hoover W. G. , Hoover C. G.

Computational Methods in Science and Technology

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2017

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tom Vol. 23, No. 1

5--8

EN

The 2016 Snook Prize has been awarded to Diego Tapias, Alessandro Bravetti, and David Sanders for their paper “Ergodicity of One-Dimensional Systems Coupled to the Logistic Thermostat”. They introduced a relatively-stiff hyperbolic tangent thermostat force and successfully tested its ability to reproduce Gibbs’ canonical distribution for three one-dimensional problems, the harmonic oscillator, the quartic oscillator, and the Mexican Hat potentials: {(q2=2); (q4=4); (q4=4) 􀀀 (q2=2)}. Their work constitutes an effective response to the 2016 Ian Snook Prize Award goal, “finding ergodic algorithms for Gibbs’ canonical ensemble using a single thermostat”. We confirm their work here and highlight an interesting feature of the Mexican Hat problem when it is solved with an adaptive integrator.

8

Singly-Thermostated Ergodicity in Gibbs’ Canonical Ensemble and the 2016 Ian Snook Prize

100%

Hoover W. G. , Hoover C. G.

Computational Methods in Science and Technology

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2016

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tom Vol. 22, No. 3

127--131

EN

For a harmonic oscillator, Nosé’s single-thermostat approach to simulating Gibbs’ canonical ensemble with dynamics samples only a small fraction of the phase space. Nosé’s approach has been improved in a series of three steps: [1] several two-thermostat sets of motion equations have been found which cover the complete phase space in an ergodic fashion; [2] sets of single-thermostat motion equations, exerting “weak control” over both forces and momenta, have been shown to be ergodic; and [3] sets of single-thermostat motion equations exerting weak control over two velocity moments provide ergodic phase-space sampling for the oscillator and for the rigid pendulum, but not for the quartic oscillator or for the Mexican Hat potential. The missing fourth step, motion equations providing ergodic sampling for anharmonic potentials requires a further advance. The 2016 Ian Snook Prize will be awarded to the author(s) of the most interesting original submission addressing the problem of finding ergodic algorithms for Gibbs’ canonical ensemble using a single thermostat.

9

Algorithms for Composing Magic Cubes

100%

Trenkler M.

Scientific Issues of Jan Długosz University in Częstochowa. Mathematics

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2003

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tom Vol. 9

103--107

EN

A magie square (a square array containing natural numbers 1,2, ... , n2 such that the sum of the numbers along every row, column and diagonal is the same) has fascinated people for centuries. In 1686, the Polish rnathematician Adamas Kochansky extended magic squares to three dimensions. An additive magic cube is a natural generalization of a magic square.

10

Zastosowanie algorytmów mrówkowych w poszukiwaniu optymalnych połączeń

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Baszun M. , Główka M.

Logistyka

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2009

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tom nr 3

CD-CD

PL

W pracy przeanalizowano podstawowe możliwości jakie stwarza użycie modyfikacji znanego algorytmu mrówkowego przy rozwiązywaniu zagadnień poszukiwania optymalnych połączeń. Wykonano implementacje programistyczne oraz przeprowadzono symulacje z użyciem tego oprogramowania. Wnioski z symulacji mogą być przydatne przy doborze ilościowych parametrów precyzujących działanie danej odmiany algorytmu. Przykładowe obliczenia wskazują na dobrą efektywność czasową znajdowania rozwiązań np. zadania komiwojażera lub zagadnień marszrutyzacji. Wyniki wskazują na możliwości aplikacyjne w ogólnie rozumianych zagadnieniach transportowych w tym optymalizowanie połączeń w transporcie pojazdowym oraz w sieciach teleinformatycznych.

EN

In the paper ant class algoriths modifications were analyzed from application point of view for logistics problems. Software implementations were been done, and various simulations were executed with the software. The results could be usefull for detailing of the algorithms from point of view of specific applications. The exampled discussion were aimed to travelling problem and routing problems. The conclusions could be usefull at vehicle transport or teleinformatic logistics.

11

The Φ4 Model, Chaos, Thermodynamics, and the 2018 SNOOK Prizes in Computational Statistical Mechanics

100%

Hoover W. G. , Hoover C. G.

Computational Methods in Science and Technology

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2018

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tom Vol. 24, No. 2

159--163

EN

The one-dimensional Φ4 Model generalizes a harmonic chain with nearest-neighbor Hooke’s-Law interactions by adding quartic potentials tethering each particle to its lattice site. In their studies of this model Kenichiro Aoki and Dimitri Kusnezov emphasized its most interesting feature: because the quartic tethers act to scatter long-wavelength phonons, Φ4 chains exhibit Fourier heat conduction. In his recent Snook-Prize work Aoki also showed that the model can exhibit chaos on the three-dimensional energy surface describing a two-body two-spring chain. That surface can include at least two distinct chaotic seas. Aoki pointed out that the model typically exhibits different kinetic temperatures for the two bodies. Evidently few-body Φ4 problems merit more investigation. Accordingly, the 2018 Prizes honoring Ian Snook (1945-2013) will be awarded to the author(s) of the most interesting work analyzing and discussing few-body Φ4 models from the standpoints of dynamical systems theory and macroscopic thermodynamics, taking into account the model’s ability to maintain a steady-state kinetic temperature gradient as well as at least two coexisting chaotic seas in the presence of deterministic chaos.

12

Instantaneous Pairing of Lyapunov Exponents in Chaotic Hamiltonian Dynamics and the 2017 Ian Snook Prizes

100%

Hoover W. G. , Hoover C. G.

Computational Methods in Science and Technology

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2017

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tom Vol. 23, No. 1

73--79

EN

The time-averaged Lyapunov exponents, f_ig, support a mechanistic description of the chaos generated in and by nonlinear dynamical systems. The exponents are ordered from largest to smallest with the largest one describing the exponential growth rate of the (small) distance between two neighboring phase-space trajectories. Two exponents, γ1 + γ2, describe the rate for areas defined by three nearby trajectories. γ1 + γ2 + γ3 is the rate for volumes defined by four nearby trajectories, and so on. Lyapunov exponents for Hamiltonian systems are symmetric. The time-reversibility of the motion equations links the growth and decay rates together in pairs. This pairing provides a more detailed explanation than Liouville’s for the conservation of phase volume in Hamiltonian mechanics. Although correct for long-time averages, the dependence of trajectories on their past is responsible for the observed lack of detailed pairing for the instantaneous “local” exponents, {γi(t)}. The 2017 Ian Snook Prizes will be awarded to the author(s) of an accessible and pedagogical discussion of local Lyapunov instability in small systems. We desire that this discussion build on the two nonlinear models described here, a double pendulum with Hooke’s-Law links and a periodic chain of Hooke’s-Law particles tethered to their lattice sites. The latter system is the ϕ4 model popularized by Aoki and Kusnezov. A four-particle version is small enough for comprehensive numerical work and large enough to illustrate ideas of general validity.

13

Finding Patterns In Given Intervals

100%

Crochemore M. , Iliopoulos C. S. , Kubica M. , Rahman M. S. , Waleń T.

Fundamenta Informaticae

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2010

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tom Vol. 101, nr 3

173-186

EN

In this paper, we study the pattern matching problem in given intervals. Depending on whether the intervals are given a priori for pre-processing, or during the query along with the pattern or, even in both the cases, we develop efficient solutions for different variants of this problem. In particular, we present efficient indexing schemes for each of the above variants of the problem.

14

The role of automation in financial trading companies

100%

Lenczewski Martins C. J.

Journal of Management and Financial Sciences

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2019

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nr 39

29-42

EN

High Frequency Trading (HFT) has significantly affected the financial market - how trade is performed, types of employees hired, technology, or even market regulations. There are arguments that important risks arrive from trade automation, especially with the use of ultra-low latency trading systems. It also gives a possibility of achieving (higher) returns more quickly with less residual losses, i.e. algorithms may lead to a lower risk of exposure than traditional ‘human' traders. A higher level of automation in trading companies is a reality, which brings important management issues. The rise in competition between algo-traders has led to the rise of the so-called Quant 2.0: the rebirth of complex algorithms and artificial intelligence to collect, extract and process information available from any source of information. im of this article is, through a literature review, to present the main issues concerning automation in financial trading companies, and how the highly probable introduction of the Blockchain technology may affect HFT and the financial market - either the general market design, or specifically, how trading is performed.

15

Directed acylic graph compression of labelled trees

100%

Paries A. , Wendling L.

Machine Graphics and Vision

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1999

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tom Vol. 8, No. 2

169-174

EN

A new algorithm for compressing labelled trees is proposed in the paper. This algorithm allows to obtain a Directed Acyclic Graph (DAG) from a labelled tree in linear time. An experimental study is also given.

16

Porównanie wydajności modyfikacji algorytmu proof-number search uwzględniających wartości remisowe

100%

Goluch T.

Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne

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2010

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tom T. 19

73-78

PL

Proof-number search to znana rodzina algorytmów służących do wyznaczania wartości pozycji w nielosowych grach dwóch graczy z pełną informacją. W wersji podstawowej pn-search doskonale radzi sobie z wyszukiwaniem strategii wygrywającej jednego z graczy. Jednak istnieje wiele znanych gier, w których obydwaj gracze posiadają jedynie strategię remisującą (Młynek, Awari, Warcaby). W niniejszej pracy porównano wydajność dwóch modyfikacji tego algorytmu, które pozwalają na określenie wartości pozycji w grze z uwzględnieniem sytuacji remisowych.

EN

Proof-number search is a well-known family of algorithms for determining the value of positions in deterministic two-player games with perfect information. The basic version of proof-number search is very good for searching for one player winning strategy. However, there are many well-known games in which both players have only a drawing strategy (Nine Men's Morris, Awari Checkers). This paper compares the performance of two modifications of this algorithm, that allow you to specify the game-theoretic value, including the draw positions.

17

On an algorithm for decision-making for the optimization of disease prediction at the primary health care level using neural network clustering

100%

Selskyy P. , Vakulenko D. , Televiak A. , Veresiuk T.

Family Medicine & Primary Care Review

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2018

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nr 2

171-175

18

Ergodic Isoenergetic Molecular Dynamics for Microcanonical-Ensemble Averages

100%

Hoover W. G. , Hoover C. G.

Computational Methods in Science and Technology

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2018

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tom Vol. 24, No. 2

155--158

EN

Considerable research has led to ergodic isothermal dynamics which can replicate Gibbs’ canonical distribution for simple (small) dynamical problems. Adding one or two thermostat forces to the Hamiltonian motion equations can give an ergodic isothermal dynamics to a harmonic oscillator, to a quartic oscillator, and even to the “Mexican-Hat” (doublewell) potential problem. We consider here a time-reversible dynamical approach to Gibbs’ “microcanonical” (isoenergetic) distribution for simple systems. To enable isoenergetic ergodicity we add occasional random rotations to the velocities. This idea conserves energy exactly and can be made to cover the entire energy shell with an ergodic dynamics. We entirely avoid the Poincaré-section holes and island chains typical of Hamiltonian chaos. We illustrate this idea for the simplest possible two-dimensional example, a single particle moving in a periodic square-lattice array of scatterers, the “cell model”.

19

A Representation Theorem for Primitive Recursive Algorithms

100%

Andary P. , Patrou B. , Valarcher P.

Fundamenta Informaticae

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2011

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tom Vol. 107, nr 4

313-330

EN

We formalize the algorithms computing primitive recursive (PR) functions as the abstract state machines (ASMs) whose running length is computable by a PR function. Then we show that there exists a programming language (implementing only PR functions) by which it is possible to implement any one of the previously defined algorithms for the PR functions in such a way that their complexity is preserved.

20

Minimization Algorithms for Time Petri Nets

100%

Półrola A. , Penczek W.

Fundamenta Informaticae

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2004

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tom Vol. 60, nr 1-4

307--331

EN

The paper presents three methods for applying partitioning algorithms, used for generating abstract models for timed automata, to the case of time Petri nets. Each of these methods is based on a different approach to the concrete semantics of a net, and can potentially be more efficient than the others in a particular case. Besides the theoretical description, we provide some preliminary experimental results, obtained from the implementation integrated with the model checking tool VeriCS.