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    Wyświetlanie 1-9 z 9
    Tytuł:
    The Fourier transform as a new approach of evaluating the internal combustion engine indicator diagram
    Autorzy:
    Łoza, Ł.
    Sitnik, L. J.
    Powiązania:
    https://bibliotekanauki.pl/articles/244677.pdf
    Data publikacji:
    2017
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    indicator diagram
    Fourier transform
    internal combustion engine
    Opis:
    In this paper, the authors present an introduction to the new method of evaluating the indicator diagram of internal combustion engine. For several years, it was observed that analyses of combustion processes have been hardly changed since they were conducted for the first time. At the moment, the diagrams are plotted more and more precisely owing to the new sensors and digital processors. Despite all of these high technical advantages, which were obviously unavailable in the past, theoretical approach for describing indicator diagram has not changed in significant way. Nowadays, the indicator diagrams are still evaluated very generally and are presented in much too idealistic way as a smooth curve of pressure changes, without any disturbances, which are being detected very easily now. Furthermore, it appears that performance improvements of the IC engines are in need of developing new methods for analysis and evaluation. The Fourier transform is a new way to look at the combustion process in the engines. It is basically a mathematical instrument for analysing different types of signals, which are transformed, from time domain into frequency domain. It enables identifying specific sinusoidal components of arbitrary signals and separates relevant ones from the noise. This allows one to see significant differences in two or more apparently similar signals and detect the crucial parts. If we treat pressure changes in time like a common signal, we can compute Fourier transform and see basic components of the diagram.
    Źródło:
    Journal of KONES; 2017, 24, 4; 173-180
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Review of possibilities of increasing the thickness of an anti-wear coating on piston rings by using specifically designed physical vapour deposition process
    Autorzy:
    Skorupa, P.
    Kaźmierczak, A.
    Błasiński, T.
    Borkowska, J.
    Krakowian, K.
    Łoza, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/245017.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    coatings
    anti-wear
    internal combustion engine
    PVD
    CVD
    thickness
    DLC
    Opis:
    The super-hard, anti-wear amorphic coatings based on carbon-like diamond (called DLC) show a promising direction in automotive industry, mainly in terms of decreasing friction coefficient in parts of internal combustion engine. However, the technology of producing DLC-coated parts, which is most often chemical vapour deposition (CVD) or physical vapour deposition (PVD) is proven to be still not perfect for achieving desired characteristics of the coating. The thickness of a coating is the main issue one should strive to improve, as the PVD methods produce films as thin as few micrometres. In such case, the coating is not only exposed to cracking, but also pitting is possible to happen. This is proven to be highly undesirable and unacceptable for this process. In addition, in case of thin films, the adhesion to the base is often too weak, despite the coating itself being extremely durable and hard. In this article, a theoretical ways to improve the process of coating are presented. The process itself is described, the achievable parameters are defined and the possible improvements are stated. The research made for the purpose of this article will be further exploited to design a process allowing creating the coating for testing of the best possible characteristics.
    Źródło:
    Journal of KONES; 2015, 22, 4; 281-286
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Various designs of the two-stroke engine heads with the valve flushed system
    Autorzy:
    Łoza, Ł.
    Kaźmierczak, A.
    Borkowska, J.
    Skorupa, P.
    Krakowian, K.
    Cienciała, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/242546.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    engine
    two-stroke
    internal combustion
    valve flushed system
    piston-controlled cam
    high petrol consumption
    oil in the petrol
    toxic by-products
    loud noise
    uneven running
    low efficiency
    Opis:
    The two-stroke engines have never acquired the popularity of the four-stroke engines due to their inherent performance limitations. The tasks of many engineering teams were to find the basic causes, which resulted in the inferior performance of these engines. Today’s task is to build a two-stroke engine whose performance could match that of a four-stroke engine in areas of common use. The most typical performance problems of a two-stroke engine are high petrol consumption caused by low efficiency, toxic by-products of combustion being emitted into the atmosphere (caused by oil present in the petrol), and uneven and loud engine noise. The greatest challenge is to achieve a good chamber purge during one stroke in which the fresh fuel mixture flows through the piston-controlled inlet port while at the same time the fumes are being exhausted through the outlet port. This in contrast with the four-stroke engines where the intake and exhaust are each done with two separate strokes. From the energy point of view, the two-stroke engine is not efficient because a certain amount of fresh fuel is being wasted in the exhaust fumes. We propose to replace the piston-controlled cam with the valve-flushed system, which will cause the combustion process to become more efficient. The purpose of this paper is to present various designs of the engine heads and analyse their performance. The goal of this proposal is to choose the best combination of these engine heads in order to achieve the optimum overall engine performance.
    Źródło:
    Journal of KONES; 2015, 22, 4; 187-190
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    The impact of the energy state of the surface of friction pairs on the friction and wear in internal combustion engines
    Autorzy:
    Borkowska, J.
    Kaźmierczak, A.
    Krakowian, K.
    Cienciała, M.
    Skorupa, P.
    Łoza, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/245015.pdf
    Data publikacji:
    2015
    Wydawca:
    Instytut Techniczny Wojsk Lotniczych
    Tematy:
    friction pairs
    top layer of surface
    sealing function
    piston ring
    cylinder sleeve
    combustion engine
    tangential force
    friction coefficient
    molecular structure
    bond
    tribology
    Opis:
    The elements creating a friction pairs are described to be very difficult in terms of defining all optimal parameters in an unequivocal way. The research on stability of friction pairs is focused on the surface and the top layer of surface in the parts concerned. The main goal is to find new design solutions and materials, thereby achieving one million kilometers of mileage to main repair in the case of internal combustion engines. The biggest structural difficulties are noticeable in friction pairs where it can be observed sliding and returning motion, which is also connected with sealing function. A typical example of such pair is piston ring – cylinder sleeve in piston – rings - cylinder unit in an internal combustion engine. Engineers are currently seeking an additional factor, which would enable gaining the reduction of tangential force by reducing the friction coefficient in elements of friction pair during operations. The surface free energy may be such factor - it results from molecular structure and nature of the bonds between the molecules present in the material. Components of surface free energy determine the tribological properties of the material, which is reflected in the stability of the units. Energy state of the surface, which is connected with chemistry and characteristics in the material, is the first step to consider about the impact on wearing in internal combustion engine. This is the main topic of this article.
    Źródło:
    Journal of KONES; 2015, 22, 4; 37-41
    1231-4005
    2354-0133
    Pojawia się w:
    Journal of KONES
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A Random Number Generator Using Ring Oscillators and SHA-256 as Post-Processing
    Autorzy:
    Łoza, S.
    Matuszewski, Ł.
    Jessa, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/963943.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    random numbers
    cryptography
    ring oscillators
    hash functions
    field programmable gate array (FPGA)
    Opis:
    Today, cryptographic security depends primarily on having strong keys and keeping them secret. The keys should be produced by a reliable and robust to external manipulations generators of random numbers. To hamper different attacks, the generators should be implemented in the same chip as a cryptographic system using random numbers. It forces a designer to create a random number generator purely digitally. Unfortunately, the obtained sequences are biased and do not pass many statistical tests. Therefore an output of the random number generator has to be subjected to a transformation called postprocessing. In this paper the hash function SHA-256 as postprocessing of bits produced by a combined random bit generator using jitter observed in ring oscillators (ROs) is proposed. All components – the random number generator and the SHA-256, are implemented in a single Field Programmable Gate Array (FPGA). We expect that the proposed solution, implemented in the same FPGA together with a cryptographic system, is more attack-resistant owing to many sources of randomness with significantly different nominal frequencies.
    Źródło:
    International Journal of Electronics and Telecommunications; 2015, 61, 2; 199-204
    2300-1933
    Pojawia się w:
    International Journal of Electronics and Telecommunications
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Digital random bit generators implemented in FPGAs offered by various manufacturers
    Autorzy:
    Kubczak, P.
    Matuszewski, Ł.
    Jessa, M.
    Łoza, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/114475.pdf
    Data publikacji:
    2015
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    true random number generator
    ring oscillator
    cryptography
    field programmable gate array (FPGA)
    Opis:
    In cryptography, we require that a random sequence should have excellent statistical properties as well as non-deterministic character. Combining multiple independent sources of randomness using the modulo two operation, significantly improves the statistical properties of the generated sequences and also affects the accumulation of true randomness generated in the oscillator sources. This is a very promising method of producing random sequences. In this paper, we compare the implementations of the RO-based combined random generator in various FPGAs technologies offered by various manufactures (Xilinx, Altera, Lattice). In this research, we used a NIST 800-22 statistical test suite to assess the statistical properties. The results show that the method of producing strings with a combined generator is the method stable in terms of technology. The results are similar for implementation in all FPGA used in the experiment. So, the proposed generator can be implemented in various programmable structures together with other components of a cryptographic system.
    Źródło:
    Measurement Automation Monitoring; 2015, 61, 7; 293-295
    2450-2855
    Pojawia się w:
    Measurement Automation Monitoring
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    A random number generator using ring oscillators and the Keccak as post-processing
    Autorzy:
    Łoza, S.
    Matuszewski, Ł.
    Jessa, M.
    Kubczak, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/114620.pdf
    Data publikacji:
    2015
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    true random number generator
    ring oscillator
    cryptography
    field programmable gate array (FPGA)
    hash function
    Opis:
    In cryptography, sequences of numbers with unpredictable elements are often required. Such sequences should pass all known statistical tests for random sequences. Because sequences produced in real circuits are biased, they do not pass many statistical tests, e.g., the distribution of numbers is not uniform. Such random number sequences should be subjected to a transformation called post-processing. In this paper, a true random number generator is considered. It uses ring oscillators and the Keccak hash function as post-processing. This paper presents only simulation conditions for this approach since the post-processing part was done using x86 architecture on a PC.
    Źródło:
    Measurement Automation Monitoring; 2015, 61, 7; 290-292
    2450-2855
    Pojawia się w:
    Measurement Automation Monitoring
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Cast Iron And Mineral Cast Applied For Machine Tool Bed - Dynamic Behavior Analysis
    Odlewy żeliwne i mineralne stosowane na łoża obrabiarek - analiza właściwości dynamicznych
    Autorzy:
    Kępczak, N.
    Pawłowski, W.
    Kaczmarek, Ł.
    Powiązania:
    https://bibliotekanauki.pl/articles/351997.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    cast iron
    mineral cast
    dynamic properties
    modal analysis
    machine tool bed
    żeliwo
    odlew mineralny
    własności dynamiczne
    analiza modalna
    łoże obrabiarki
    Opis:
    Cast iron and mineral cast are the materials most often used in the machine structural elements design (bodies, housings, machine tools beds etc.). The materials significantly differ in physical and mechanical properties. The ability to suppress vibration is one of the most important factors determining the dynamic properties of the machine and has a significant impact on the machining capabilities of a machine tool. Recent research and development trends show that there is a clear tendency to move away from the traditional iron casting to the mineral casting, due to better dynamic properties of the latter. However mineral cast as a structural material for the whole machine tools bed turns out to be insufficient due to its poor mechanical strength properties. The best solution should benefit from the advantages of the cast iron and mineral cast materials while minimizing their drawbacks. The paper presents numerical modal analysis of two lathe beds: the first one made of gray cast iron and the second one made of hybrid connection of cast iron and mineral cast. The analysis was conducted in order to determine the dynamic properties of two bodies of similar shapes made in the traditional (cast iron) and innovative hybrid (cast iron and mineral cast) technology. In addition, an analysis of the static structure rigidity of the two beds was performed. During the simulation studies it was found a significant increase in dynamic stiffness and static rigidity of the machine tool body made of hybrid connection of cast iron and mineral cast. The results of numerical simulations have confirmed the desirability of using hybrid construction because the dynamic properties of such a body are more advantageous in comparison with the conventional body made of cast iron.
    Żeliwo oraz odlewy mineralne są materiałami konstrukcyjnymi najczęściej wykorzystywanymi w dziedzinie projektowania elementów strukturalnych maszyn (korpusy, obudowy, łoża obrabiarek). Te materiały znacząco różnią się pod względem zarówno właściwości fizycznych, jak i mechanicznych. Zdolność do tłumienia drgań jest jednym z najważniejszych czynników determinujących właściwości dynamiczne urządzenia i ma znaczący wpływ na możliwości obróbkowe maszyny technologicznej. Najnowsze badania oraz trendy rozwojowe pokazują, że istnieje wyraźna tendencja do odchodzenia od tradycyjnych odlewów żeliwnych w kierunku odlewów mineralnych, ze względu na lepsze właściwości dynamicznych tych ostatnich. Jednakże odlewy mineralne jako materiał konstrukcyjny na całe łoże obrabiarki okazuje się być niewystarczający ze względu na słabe właściwości mechaniczne. Najlepsze rozwiązanie powinno korzystać z zalet żeliwa i odlewów mineralnych, jednocześnie minimalizując wady obu materiałów. W artykule przedstawiono teoretyczną analizę modalną dwóch korpusów obrabiarki: jednego wykonanego z żeliwa szarego oraz drugiego wykonanego z hybrydowego połączenia żeliwa i odlewu mineralnego. Analiza została przeprowadzona w celu określenia właściwości dynamicznych dwóch korpusów o podobnych kształtach wykonanych w tradycyjnej oraz nowatorskiej technologii odlewniczej. Dodatkowo przeprowadzono analizę sztywności statycznej konstrukcji obu korpusów. Podczas badań symulacyjnych stwierdzono, wzrost sztywności dynamicznej oraz wzrost sztywności statycznej korpusu obrabiarki wykonanego z hybrydowego połączenia żeliwa szarego i odlewu mineralnego. Otrzymane wyniki badań teoretycznych potwierdziły celowość stosowania budowy hybrydowej, ponieważ właściwości dynamiczne tak wytworzonego korpusu są korzystniejsze w porównaniu z korpusem wykonanym z tradycyjnego odlewu żeliwnego.
    Źródło:
    Archives of Metallurgy and Materials; 2015, 60, 2A; 1023-1029
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Wykorzystanie funkcji skrótu do poprawy właściwości statystycznych ciągu liczb losowych
    Using a hash function to improve statistical properties of true random number sequences
    Autorzy:
    Matuszewski, Ł.
    Łoza, Sz.
    Jessa, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/152803.pdf
    Data publikacji:
    2014
    Wydawca:
    Stowarzyszenie Inżynierów i Techników Mechaników Polskich
    Tematy:
    generator liczb prawdziwie losowych
    generator pierścieniowy
    kryptografia
    funkcja skrótu
    losowość i pseudolosowość
    true random number generator
    ring oscillator
    cryptography
    hash function
    randomness and pseudo-randomness
    Opis:
    W pracy przedstawiono sposób wykorzystania funkcji skrótu, na przykładzie funkcji SHA-256 (ang. Secure Hash Algorithm), do poprawy właściwości statystycznych ciągów liczb losowych. W badaniach wykorzystano pakiet testów statystycznych NIST 800-22 do oceny właściwości wytwarzanego ciągu metodę restartów i test chi kwadrat, dzięki którym możliwe jest wykazanie, czy dany generator produkuje ciąg z przeważającymi elementami deterministycznymi czy niedeterministycznymi. Proponowany układ może być z powodzeniem zaimplementowany w każdym układzie FPGA (ang. Field Programmable Gate Array).
    Random sequences play a key role in many contemporary cryptographic systems. To increase the efficiency and robustness to attacks, it is recommended to integrate a source of random numbers with a cryptographic system using these numbers. Unfortunately, the list of non-deterministic physical phenomena available in digital circuits is rather short and practically includes jitter and metastable states. It is expected that the generator produces sequences that pass all known statistical tests and that the sequences are unpredictable and attack resistant. A generator that satisfies these expectations is named a true random number generator (TRNG). This paper presents a novel method for producing random bits with the use of jitter observed in ring oscillators. The method uses a Galois ring oscillator introduced recently and the hash function. To assess the quality of output sequences, the statistical test suite prepared by National Institute of Standards and Technology (NIST) and the restart mechanism were used. The proposed system can be implemented in any Field Programmable Gate Array (FPGA).
    Źródło:
    Pomiary Automatyka Kontrola; 2014, R. 60, nr 7, 7; 456-458
    0032-4140
    Pojawia się w:
    Pomiary Automatyka Kontrola
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-9 z 9

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