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    Wyświetlanie 1-9 z 9
    Tytuł:
    Interative method of calculation of originally circular-symmetric structures
    Iteracyjna metoda obliczania modyfikowanych konstrukcji pierwotnie kołowo-symetrycznych
    Autorzy:
    Pruputniewicz, S.
    Pruputniewicz, T.
    Powiązania:
    https://bibliotekanauki.pl/articles/396386.pdf
    Data publikacji:
    2005
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    mechanika konstrukcji
    konstrukcje modyfikowane
    circular-symmetric structures
    modification
    cyclic matrices
    Opis:
    The paper proposes an iterative method of calculation of modified, originally circular-symmetric structures. The method applies a cyclical (or quasi-cyclical) stiffness matrix of the original structure in each iteration step. A lot of modified systems which differ considerably from circular-symmetric ones (lack of some elements, strengthening, additional supports) have been calculated. The obtained results indicate that although the algorithm is not unconditionally convergent, exact solutions are often received even for considerable changes in the original structure. Operations on considerably smaller matrices than the full ones describing a system completely, compensate for the necessity of performing a greater number of iterations than when applying other methods of modification.
    W pracy zaproponowano iteracyjny sposób obliczania modyfikowanych konstrukcji pierwotnie kołowo-symetrycznych, w którym na każdym kroku iteracji korzysta sięz cyklicznej (lub quasicyklicznej) macierzy sztywności konstrukcji pierwotnej. Wykonano obliczenia wielu modyfikowanych układów znacznie różniących się od kołowo-symetrycznych (brak niektórych elementów, wzmocnienia, dodatkowe podpory). Uzyskane wyniki wskazują na to, że chociaż algorytm nie jest bezwarunkowo zbieżny to nawet przy znacznych zmianach w konstrukcji pierwotnej uzyskuje się często dokładne rozwiązania. Działanie na macierzach znacznie mniejszych od pełnych macierzy opisujących układ znacząco rekompensuje koniecznośś wykonania wiekszej liczby iteracji niż przy korzystaniu z innych metod.
    Źródło:
    Civil and Environmental Engineering Reports; 2005, 1; 243-259
    2080-5187
    2450-8594
    Pojawia się w:
    Civil and Environmental Engineering Reports
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Evaluation of water impact for symmetric wedge by experimental and numerical methods
    Autorzy:
    Nikfarjam, M.
    Koto, J.
    Yaakob, O. B.
    Seif, M. S.
    Aref, A.
    Powiązania:
    https://bibliotekanauki.pl/articles/266182.pdf
    Data publikacji:
    2019
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    hydrodynamika
    ciśnienie uderzenia
    statek
    symmetric wedge
    hydrodynamic impact
    impact pressure
    Opis:
    Evaluation of impact loads when a ship hull contacts the wave surface is one of the main issues for researchers who are going to design the structure of marine vehicles. In this paper, the results of experimental tests and numerical modeling of the distribution of pressure on different wedge-shaped models are reported and the effect of related parameters such as the deadrise angles, the weight and drop heights, is assessed. The output of analyses and the results can give appropriate approximations of the maximum impact pressures for the geometries that are similar to marine vehicle’s hull sections to estimate the hydrodynamic impact loads in different sea-states. In addition, other effective parameters such as the impact speed, acceleration and water entry process can be used for evaluating the performance of such crafts.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2019, 24, 1; 221-230
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Some properties of the spectral radius of a set of matrices
    Autorzy:
    Czornik, A.
    Jurgaś, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/908427.pdf
    Data publikacji:
    2006
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    promień spektralny
    podpromień spektralny
    macierz symetryczna
    spectral radius
    spectral subradius
    symmetric matrices
    Opis:
    In this paper we show new formulas for the spectral radius and the spectral subradius of a set of matrices. The advantage of our results is that we express the spectral radius of any set of matrices by the spectral radius of a set of symmetric positive definite matrices. In particular, in one of our formulas the spectral radius is expressed by singular eigenvalues of matrices, whereas in the existing results it is expressed by eigenvalues.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2006, 16, 2; 183-188
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Slowly vibrating axially symmetric bodies-transverse flow
    Autorzy:
    Srivastava, D. K.
    Powiązania:
    https://bibliotekanauki.pl/articles/1839883.pdf
    Data publikacji:
    2021
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    płyn newtonowski
    przepływ osiowy
    metoda Stokesa
    Stokes drag
    axially symmetric bodies
    Newtonian fluid
    axial flow
    Opis:
    Stokes drag on axially symmetric bodies vibrating slowly along the axis of symmetry placed under a uniform transverse flow of the Newtonian fluid is calculated. The axially symmetric bodies of revolution are considered with the condition of continuously turning tangent. The results of drag on sphere, spheroid, deformed sphere, egg-shaped body, cycloidal body, Cassini oval, and hypocycloidal body are found to be new. The numerical values of frictional drag on a slowly vibrating needle shaped body and flat circular disk are calculated as particular cases of deformed sphere.
    Źródło:
    International Journal of Applied Mechanics and Engineering; 2021, 26, 1; 226-250
    1734-4492
    2353-9003
    Pojawia się w:
    International Journal of Applied Mechanics and Engineering
    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:
    A parallel block Lanczos algorithm and its implementation for the evaluation of some eigenvalues of large sparse symmetric matrices on multicomputers
    Autorzy:
    Guarracino, M. R.
    Perla, F.
    Zanetti, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/908413.pdf
    Data publikacji:
    2006
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    cluster architecture
    symmetric block Lanczos algorithm
    sparse matrices
    parallel eigensolver
    algorytm Lanczosa
    macierze rzadkie
    architektura klastrowa
    Opis:
    In the present work we describe HPEC (High Performance Eigenvalues Computation), a parallel software package for the evaluation of some eigenvalues of a large sparse symmetric matrix. It implements an efficient and portable Block Lanczos algorithm for distributed memory multicomputers. HPEC is based on basic linear algebra operations for sparse and dense matrices, some of which have been derived by ScaLAPACK library modules. Numerical experiments have been carried out to evaluate HPEC performance on a cluster of workstations with test matrices from Matrix Market and Higham’s collections. A comparison with a PARPACKroutine is also detailed. Finally, parallel performance is evaluated on random matrices, using standard parameters.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2006, 16, 2; 241-249
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The Stability of an Irrigation Canal System
    Autorzy:
    Bounit, H.
    Powiązania:
    https://bibliotekanauki.pl/articles/908097.pdf
    Data publikacji:
    2003
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    matematyka
    Saint-Venant equation
    dimensionless
    symmetric hyperbolic equation
    internal stability
    transfer functions
    input-output stability
    regular systems
    Opis:
    In this paper we examine the stability of an irrigation canal system. The system considered is a single reach of an irrigation canal which is derived from Saint-Venant's equations. It is modelled as a system of nonlinear partial differential equations which is then linearized. The linearized system consists of hyperbolic partial differential equations. Both the control and observation operators are unbounded but admissible. From the theory of symmetric hyperbolic systems, we derive the exponential (or internal) stability of the semigroup underlying the system. Next, we compute explicitly the transfer functions of the system and we show that the input-output (or external) stability holds. Finally, we prove that the system is regular in the sense of (Weiss, 1994) and give various properties related to its transfer functions.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2003, 13, 4; 453-468
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Scalable PP-1 block cipher
    Autorzy:
    Bucholc, K.
    Chmiel, K.
    Grocholewska-Czuryło, A.
    Idzikowska, E.
    Janicka-Lipska, I.
    Stokłosa, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/907705.pdf
    Data publikacji:
    2010
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    resistance against cryptanalysis
    symmetric cipher
    scalable cipher
    S-box construction
    error detection
    szyfrowanie symetryczne
    szyfrowanie skalowalne
    kryptoanaliza
    wykrywanie błędu
    Opis:
    A totally involutional, highly scalable PP-1 cipher is proposed, evaluated and discussed. Having very low memory requirements and using only simple and fast arithmetic operations, the cipher is aimed at platforms with limited resources, e.g., smartcards. At the core of the cipher's processing is a carefully designed S-box. The paper discusses in detail all aspects of PP-1 cipher design including S-box construction, permutation and round key scheduling. The quality of the PP-1 cipher is also evaluated with respect to linear cryptanalysis and other attacks. PP-1's concurrent error detection is also discussed. Some processing speed test results are given and compared with those of other ciphers.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2010, 20, 2; 401-411
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Hybrid cryptography with a one-time stamp to secure contact tracing for COVID-19 infection
    Autorzy:
    El-Douh, Ahmed Abdel-Rahim
    Lu, Song Feng
    Elkouny, Abdelatif A.
    Amein, A.S.
    Powiązania:
    https://bibliotekanauki.pl/articles/2055157.pdf
    Data publikacji:
    2022
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    hybrid cryptography
    digital signature
    RSA
    AES
    asymmetric cryptography
    symmetric cryptography
    cybersecurity
    COVID-19
    kryptografia hybrydowa
    podpis elektroniczny
    kryptografia asymetryczna
    kryptografia symetryczna
    cyberbezpieczeństwo
    Opis:
    The COVID-19 pandemic changed the lives of millions of citizens worldwide in the manner they live and work to the so-called new norm in social standards. In addition to the extraordinary effects on society, the pandemic created a range of unique circumstances associated with cybercrime that also affected society and business. The anxiety due to the pandemic increased the probability of successful cyberattacks and as well as number and range. For public health officials and communities, location tracking is an essential component in the their efforts to combat the disease. The governments provide a lot of mobile apps to help health officials to trace the infected persons and contact them to aid and follow up on the health status, which requires an exchange of data in different forms. This paper presents the one-time stamp model as a new cryptography technique to secure different contact forms and protect the privacy of the infected person. The one-time stamp hybrid model consists of a combination of symmetric, asymmetric, and hashing cryptography in an entirely new way that is different from conventional and similar existing algorithms. Several experiments have been carried out to analyze and examine the proposed technique. Also, a comparison study has been made between our proposed technique and other state-of-the-art alternatives. Results show that the proposed one-time stamp model provides a high level of security for the encryption of sensitive data relative to other similar techniques with no extra computational cost besides faster processing time.
    Źródło:
    International Journal of Applied Mathematics and Computer Science; 2022, 32, 1; 139--146
    1641-876X
    2083-8492
    Pojawia się w:
    International Journal of Applied Mathematics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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