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    Wyświetlanie 1-13 z 13
    Tytuł:
    Entropy generation on MHD slip flow over a stretching cylinder with heat generation/absorption
    Autorzy:
    Jain, S.
    Bohra, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/264521.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    magnetohydrodynamika
    wytwarzanie ciepła
    poślizg
    entropia
    magnetohydrodynamic
    heat generation
    slip
    entropy
    Opis:
    In the present study, we have investigated entropy generation on a magnetohydrodynamic fluid flow and heat transfer over a stretching cylinder with a porous medium in slip flow regime. A uniform heat source and radiation is also considered. Similarity transformation has been applied for making an ordinary differential equation from nonlinear governing partial differential equations. The numerical solution for the set of nonlinear ordinary differential equations has been obtained by using the fourth-order Runge-Kutta scheme together with the shooting method. The effects of pertinent parameters such as the magnetic field parameter, permeability parameter, slip parameter, Prandtl number and radiation parameter on the fluid velocity distribution, temperature distribution, entropy generation and Bejan number are discussed graphically.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2018, 23, 2; 413-428
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Local correlation and entropy maps as tools for detecting defects in industrial images
    Autorzy:
    Skubalska-Rafajłowicz, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/908047.pdf
    Data publikacji:
    2008
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    wykrywanie uszkodzenia
    przetwarzanie obrazu
    korelacja lokalna
    defects detection
    image processing
    local correlation
    entropy map
    Opis:
    The aim of this paper is to propose two methods of detecting defects in industrial products by an analysis of gray level images with low contrast between the defects and their background. An additional difficulty is the high nonuniformity of the background in different parts of the same image. The first method is based on correlating subimages with a nondefective reference subimage and searching for pixels with low correlation. To speed up calculations, correlations are replaced by a map of locally computed inner products. The second approach does not require a reference subimage and is based on estimating local entropies and searching for areas with maximum entropy. A nonparametric estimator of local entropy is also proposed, together with its realization as a bank of RBF neural networks. The performance of both methods is illustrated with an industrial image.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2008, 18, 1; 41-47
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Chemically reacting Jeffrey fluid flow over a deformable porous layer with entropy generation analysis
    Autorzy:
    Das, Utpal Jyoti
    Powiązania:
    https://bibliotekanauki.pl/articles/2174171.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    odkształcenie
    warstwa porowata
    dyfuzja termiczna
    deformable porous layer
    Jeffrey fluid
    entropy generation
    Bejan number
    thermal diffusion
    Opis:
    Entropy generation of a steady Jeffrey fluid flow over a deformable vertical porous layer is analysed with consideration of a first-order chemical reaction and thermal diffusion. The porous material is modelled as a homogeneous binary mixture of fluid and solid phases where each point in the binary mixture is occupied concurrently by the fluid and solid. The combined phenomenon of solid deformation and fluid movement is taken into account. The impact of relevant parameters on the fluid velocity, solid displacement, temperature and concentration profiles is discussed. It is noticed that the Jeffrey fluid parameter enhances the entropy generation number, fluid velocity and solid displacement profiles, but a reverse effect is seen for the Bejan number. Further, entropy generation, fluid velocity and solid displacement reduce due to the higher estimates of the chemical reaction parameter, while the Bejan number enhances.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2022, 27, 3; 36--48
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Relationship Between Energy and Information
    Autorzy:
    Górecki, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/911194.pdf
    Data publikacji:
    2000
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    entropy of information
    energy
    stabilization
    DC motor
    white noise
    Opis:
    Two ways of speed stabilization of the D.C. motor are considered. One way consists in the use of additional kinetic energy accumulated in a wheel with a large moment of inertia J. The other consists in the use of additional information supplied by a feedback loop with gain K. In both the cases the motor is under the influence of the same white Gaussion noise. These two ways of stabilization are compared under the assumption of the same value of the speed error in the steady state.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2000, 10, 2; 405-411
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Transient velocity and steady state entropy generation in a microfluidic Couette flow containing charged nano particles
    Autorzy:
    Gorla, R. S. R.
    Gireesha, B. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/264851.pdf
    Data publikacji:
    2015
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    transient velocity
    steady state entropy generation
    microfluidic Couette flow
    charged nanoparticles
    Bejan number and Brinkman number
    przepływ Couette'a
    liczba Brinkmana
    nanocząsteczki
    Opis:
    An analysis has been provided to determine the transient velocity and steady state entropy generation in a microfluidic Couette flow influenced by electro-kinetic effect of charged nanoparticles. The equation for calculating the Couette flow velocity profile is derived for transient flow. The solutions for momentum and energy equations are used to get the exact solution for the dimensionless velocity ratio and dimensionless entropy generation number. The effects of the dimensionless entropy generation number, Bejan number, irreversibility ratio, entropy generation due to fluid friction and due to heat transfer on dimensionless time, relative channel height, Brinkman number, dimensionless temperature ratio, nanoparticle volume fraction are analyzed.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2015, 20, 4; 787-804
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An information based approach to stochastic control problems
    Autorzy:
    Bania, Piotr
    Powiązania:
    https://bibliotekanauki.pl/articles/330505.pdf
    Data publikacji:
    2020
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    stochastic control
    feedback control
    information
    entropy
    sterowanie stochastyczne
    sprzężenie zwrotne
    entropia
    Opis:
    An information based method for solving stochastic control problems with partial observation is proposed. First, information-theoretic lower bounds of the cost function are analysed. It is shown, under rather weak assumptions, that reduction in the expected cost with closed-loop control compared with the best open-loop strategy is upper bounded by a non-decreasing function of mutual information between control variables and the state trajectory. On the basis of this result, an information based control (IBC) method is developed. The main idea of IBC consists in replacing the original control task by a sequence of control problems that are relatively easy to solve and such that information about the system state is actively generated. Two examples of the IBC operation are given. It is shown that the method is able to find an optimal solution without using dynamic programming at least in these examples. Hence the computational complexity of IBC is substantially smaller than that of dynamic programming, which is the main advantage of the proposed method.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2020, 30, 1; 23-34
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Lightweight compression with encryption based on asymmetric numeral systems
    Autorzy:
    Duda, Jarosław
    Niemiec, Marcin
    Powiązania:
    https://bibliotekanauki.pl/articles/2201015.pdf
    Data publikacji:
    2023
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    symmetric cryptography
    lightweight cryptography
    data compression
    entropy coding
    kryptografia symetryczna
    kryptografia lekka
    kompresja danych
    kodowanie entropijne
    Opis:
    Data compression combined with effective encryption is a common requirement of data storage and transmission. Low cost of these operations is often a high priority in order to increase transmission speed and reduce power usage. This requirement is crucial for battery-powered devices with limited resources, such as autonomous remote sensors or implants. Well-known and popular encryption techniques are frequently too expensive. This problem is on the increase as machine-to-machine communication and the Internet of Things are becoming a reality. Therefore, there is growing demand for finding trade-offs between security, cost and performance in lightweight cryptography. This article discusses asymmetric numeral systems-an innovative approach to entropy coding which can be used for compression with encryption. It provides a compression ratio comparable with arithmetic coding at a similar speed as Huffman coding; hence, this coding is starting to replace them in new compressors. Additionally, by perturbing its coding tables, the asymmetric numeral system makes it possible to simultaneously encrypt the encoded message at nearly no additional cost. The article introduces this approach and analyzes its security level. The basic application is reducing the number of rounds of some cipher used on ANS-compressed data, or completely removing an additional encryption layer when reaching a satisfactory protection level.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2023, 33, 1; 45--55
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    An active exploration method for data efficient reinforcement learning
    Autorzy:
    Zhao, Dongfang
    Liu, Jiafeng
    Wu, Rui
    Cheng, Dansong
    Tang, Xianglong
    Powiązania:
    https://bibliotekanauki.pl/articles/331205.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    reinforcement learning
    information entropy
    PILCO
    data efficiency
    uczenie ze wzmocnieniem
    entropia informacji
    wydajność danych
    Opis:
    Reinforcement learning (RL) constitutes an effective method of controlling dynamic systems without prior knowledge. One of the most important and difficult problems in RL is the improvement of data efficiency. Probabilistic inference for learning control (PILCO) is a state-of-the-art data-efficient framework that uses a Gaussian process to model dynamic systems. However, it only focuses on optimizing cumulative rewards and does not consider the accuracy of a dynamic model, which is an important factor for controller learning. To further improve the data efficiency of PILCO, we propose its active exploration version (AEPILCO) that utilizes information entropy to describe samples. In the policy evaluation stage, we incorporate an information entropy criterion into long-term sample prediction. Through the informative policy evaluation function, our algorithm obtains informative policy parameters in the policy improvement stage. Using the policy parameters in the actual execution produces an informative sample set; this is helpful in learning an accurate dynamic model. Thus, the AEPILCOalgorithm improves data efficiency by learning an accurate dynamic model by actively selecting informative samples based on the information entropy criterion. We demonstrate the validity and efficiency of the proposed algorithm for several challenging controller problems involving a cart pole, a pendubot, a double pendulum, and a cart double pendulum. The AEPILCO algorithm can learn a controller using fewer trials compared to PILCO. This is verified through theoretical analysis and experimental results.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2019, 29, 2; 351-362
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Closed system of coupling effects in generalized thermo-elastoplasticity
    Autorzy:
    Śloderbach, Z.
    Powiązania:
    https://bibliotekanauki.pl/articles/266002.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    termodynamika
    sprzęgło
    naprężenia
    odkształcenia
    tworzywa sztuczne
    thermodynamic potentials
    couplings effects
    stresses
    deformations
    temperature
    entropy
    enthalpy
    constitutive and rate equations
    yield surface
    plastic potential
    Opis:
    In this paper, the field equations of the generalized coupled thermoplasticity theory are derived using the postulates of classical thermodynamics of irreversible processses. Using the Legendre transformations two new thermodynamics potentials P and S depending upon internal thermodynamic forces Π are introduced. The most general form for all the thermodynamics potentials are assumed instead of the usually used additive form. Due to this assumption, it is possible to describe all the effects of thermomechanical couples and also the elastic-plastic coupling effects observed in such materials as rocks, soils, concretes and in some metalic materials. In this paper not only the usual postulate of existence of a dissipation qupotential (the Gyarmati postulate) is used to derive the velocity equation. The plastic flow constitutive equations have the character of non-associated flow laws even when the Gyarmati postulate is assumed. In general formulation, the plastic strain rate tensor is normal to the surface of the generalized function of plastic flow defined in the the space of internal thermodynamic forces Π but is not normal to the yield surface. However, in general formulation and after the use the Gyarmati postulate, the direction of the sum of the plastic strain rate tensor and the coupled elastic strain rate tensor is normal to the yield surface.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2016, 21, 2; 461-483
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Dynamic stability and spatial heterogeneity in the individual-based modelling of a Lotka-Volterra gas
    Autorzy:
    Waniewski, J.
    Jędruch, W.
    Żołek, N. S.
    Powiązania:
    https://bibliotekanauki.pl/articles/907374.pdf
    Data publikacji:
    2004
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    równanie Lotka-Volterra
    entropia
    współczynnik korelacji
    predator-prey system
    entropy
    correlation coefficient
    Opis:
    Computer simulation of a few thousands of particles moving (approximately) according to the energy and momentum conservation laws on a tessellation of 800 x 800 squares in discrete time steps and interacting according to the predator-prey scheme is analyzed. The population dynamics are described by the basic Lotka-Volterra interactions (multiplication of preys, predation and multiplication of predators, death of predators), but the spatial effects result in differences between the system evolution and the mathematical description by the Lotka-Volterra equations. The spatial patterns were evaluated using entropy and a cross correlation coefficient for the spatial distribution of both populations. In some simulations the system oscillated with variable amplitude but rather stable period, but the particle distribution departed from the (quasi) homogeneous state and did not return to it. The distribution entropy oscillated in the same rhythm as the population, but its value was smaller than in the initial homogeneous state. The cross correlation coefficient oscillated between positive and negative values. Its average value depended on the space scale applied for its evaluation with the negative values on the small scale (separation of preys from predators) and the positive values on the large scale (aggregation of both populations). The stability of such oscillation patterns was based on a balance of the population parameters and particle mobility. The increased mobility (particle mixing) resulted in unstable oscillations with high amplitude, sustained homogeneity of the particle distribution, and final extinction of one or both populations.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2004, 14, 2; 139-147
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A fuzzy approach to option pricing in a Levy process setting
    Autorzy:
    Nowak, P.
    Romaniuk, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/330572.pdf
    Data publikacji:
    2013
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    option pricing
    Lévy process
    minimal entropy
    martingale measure
    fuzzy sets
    Monte Carlo simulation
    wycena opcji
    entropia minimalna
    zbiór rozmyty
    symulacja Monte Carlo
    Opis:
    In this paper the problem of European option valuation in a Levy process setting is analysed. In our model the underlying asset follows a geometric Levy process. The jump part of the log-price process, which is a linear combination of Poisson processes, describes upward and downward jumps in price. The proposed pricing method is based on stochastic analysis and the theory of fuzzy sets.We assume that some parameters of the financial instrument cannot be precisely described and therefore they are introduced to the model as fuzzy numbers. Application of fuzzy arithmetic enables us to consider various sources of uncertainty, not only the stochastic one. To obtain the European call option pricing formula we use the minimal entropy martingale measure and Levy characteristics.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2013, 23, 3; 613-622
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Signed directed graph based modeling and its validation from process knowledge and process data
    Autorzy:
    Yang, F.
    Shah, S. L.
    Xiao, D.
    Powiązania:
    https://bibliotekanauki.pl/articles/331384.pdf
    Data publikacji:
    2012
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    graf skierowany
    diagnostyka uszkodzeń
    system oceny zagrożeń
    signed directed graph
    transfer entropy
    process topology
    fault diagnosis
    process hazard assessment
    Opis:
    This paper is concerned with the fusion of information from process data and process connectivity and its subsequent use in fault diagnosis and process hazard assessment. The Signed Directed Graph (SDG), as a graphical model for capturing process topology and connectivity to show the causal relationships between process variables by material and information paths, has been widely used in root cause and hazard propagation analysis. An SDG is usually built based on process knowledge as described by piping and instrumentation diagrams. This is a complex and experience-dependent task, and therefore the resulting SDG should be validated by process data before being used for analysis. This paper introduces two validation methods. One is based on cross-correlation analysis of process data with assumed time delays, while the other is based on transfer entropy, where the correlation coefficient between two variables or the information transfer from one variable to another can be computed to validate the corresponding paths in SDGs. In addition to this, the relationship captured by data-based methods should also be validated by process knowledge to confirm its causality. This knowledge can be realized by checking the reachability or the influence of one variable on another based on the corresponding SDG which is the basis of causality. A case study of an industrial process is presented to illustrate the application of the proposed methods.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2012, 22, 1; 41-53
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Efficient decision trees for multi-class support vector machines using entropy and generalization error estimation
    Autorzy:
    Kantavat, P.
    Kijsirikul, B.
    Songsiri, P.
    Fukui, K. I.
    Numao, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/330532.pdf
    Data publikacji:
    2018
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    support vector machine
    multi-class classification
    generalization error
    decision tree
    maszyna wektorów wsparcia
    klasyfikacja wieloklasowa
    błąd generalizacji
    drzewo decyzyjne
    Opis:
    We propose new methods for support vector machines using a tree architecture for multi-class classification. In each node of the tree, we select an appropriate binary classifier, using entropy and generalization error estimation, then group the examples into positive and negative classes based on the selected classifier, and train a new classifier for use in the classification phase. The proposed methods can work in time complexity between O(log2 N) and O(N), where N is the number of classes. We compare the performance of our methods with traditional techniques on the UCI machine learning repository using 10-fold cross-validation. The experimental results show that the methods are very useful for problems that need fast classification time or those with a large number of classes, since the proposed methods run much faster than the traditional techniques but still provide comparable accuracy.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2018, 28, 4; 705-717
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-13 z 13

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