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    Wyświetlanie 1-14 z 14
    Tytuł:
    Effect of Volume Ratio of Heat Rejection Process on Performance of an Atkinson Cycle
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1030546.pdf
    Data publikacji:
    2018-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    Atkinson cycle
    heat rejection process
    Opis:
    The objective of this study is to analyze the effect of volume ratio of heat rejection process on the performance of dual cycle. Using finite-time thermodynamics, the relations between the volume ratio of heat rejection, the thermal efficiency, the power output, the heat transfer losses, the friction power and the compression ratio for an air standard Atkinson cycle have been derived. In the model, the nonlinear relation between the specific heats of working fluid and its temperature, the frictional loss and heat leakage loss are considered. The results show that the power output and the thermal efficiency first increase with the increase of volume ratio of heat rejection process and then start to decrease. The optimum value of the volume ratio of heat rejection which maximizes the power output is higher than that which maximizes the thermal efficiency, while the optimum value of the compression ratio which maximizes the power output is lower than that which maximizes the thermal efficiency. The results obtained in the present study provide guidance to the performance evaluation and improvement for practical internal combustion engines.
    Źródło:
    Acta Physica Polonica A; 2018, 133, 1; 201-205
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effect of Expansion-Compression Ratio on Performance of the Miller cycle
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1418112.pdf
    Data publikacji:
    2012-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.70.Ln
    82.60.Fa
    88.05.-b
    88.20.td
    Opis:
    The objective of this study is to analyze the effect of expansion-compression ratio on the performance of dual cycle. Using finite-time thermodynamics, the relations between thermal efficiency, power output and compression ratio for an air standard Miller cycle have been derived. In the model, the nonlinear relation between the specific heats of working fluid and its temperature, the frictional loss computed according to the mean velocity of the piston, and heat transfer loss are considered. The results show that the power output first increases with the increasing expansion-compression ratio and then starts to decrease. Comparisons of the power output of the Miller, Otto, and Atkinson cycles show that if compression ratio is less than certain value, the power output for Otto cycle is higher, while if compression ratio exceeds certain value, the power output for the Miller cycle is higher. With further increase in compression ratio, the power output for Atkinson cycle is higher. In high compression ratio, the power output of the Miller cycle is higher. The results obtained in the present study provide guidance to the performance evaluation and improvement for practical internal combustion engines.
    Źródło:
    Acta Physica Polonica A; 2012, 122, 4; 645-649
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Second Law Analysis on an Air-Standard Miller Engine
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1398906.pdf
    Data publikacji:
    2016-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.70.Ln
    82.60.Fa
    88.05.-b
    Opis:
    Performance analysis has been carried out for air-standard Miller engine using second law analysis. The relations of the second law efficiency versus compression ratio, the second law efficiency versus first law efficiency as well as the exergy versus compression ratio are obtained. The results show that the curve of second law efficiency versus first law efficiency is a parabolic-like one. The results also show that, throughout the compression ratio range, the second law efficiency increases when the expansion-compression ratio increases.
    Źródło:
    Acta Physica Polonica A; 2016, 129, 6; 1079-1082
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Thermodynamic Modeling of an Atkinson Cycle with respect to Relative Air-Fuel Ratio, Fuel Mass Flow Rate and Residual Gases
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399496.pdf
    Data publikacji:
    2013-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.70.Ln
    82.60.Fa
    88.05.-b
    Opis:
    The performance of an air standard Atkinson cycle is analyzed using finite-time thermodynamics. The results show that if the compression ratio is less than a certain value, the power output increases with increasing relative air-fuel ratio, while if the compression ratio exceeds a certain value, the power output first increases and then starts to decrease with increase of relative air-fuel ratio. With a further increase in compression ratio, the increase in relative air-fuel ratio results in decrease of the power output. Throughout the compression ratio range, the power output increases with increase of fuel mass flow rate. The results also show that if the compression ratio is less than a certain value, the power output increases with increase of residual gases, on the contrast, if the compression ratio exceeds a certain value, the power output decreases with increase of residual gases. The results obtained herein can provide guidance for the design of practical Atkinson engines.
    Źródło:
    Acta Physica Polonica A; 2013, 124, 1; 29-34
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Performance Analysis of a Dual Cycle Engine with Considerations of Pressure Ratio and Cut-Off Ratio
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1535596.pdf
    Data publikacji:
    2010-10
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.70.Ln
    82.60.Fa
    88.05.-b
    Opis:
    The dual cycle is a better approximation to the modern high speed compression ignition engine than either the Diesel cycle or the Otto cycle. Therefore, this study is aimed at investigating the effects of pressure and cut-off ratios on the dual cycle performance with considerations of heat transfer loss, variable specific heat ratio and friction irreversible losses. By using finite-time thermodynamics theory, the relations between the power output and the compression ratio, between the thermal efficiency and the compression ratio, as well as the optimal relation between power output and the efficiency of the cycle are obtained. The results show that if compression ratio is smaller than certain value, the increase of pressure ratio and the decrease of cut-off ratio make the power output bigger. While if compression ratio exceeds certain value, the power output first increases and then starts to decline as pressure ratio and cut-off ratio are increased. With further increase in compression ratio, the power output decreases with increasing pressure ratio and decreasing cut-off ratio. The effects of pressure and cut-off ratios on the variation of the thermal efficiency with compression ratio are similar to those for the power output. The results obtained in this work can provide significant guidance for the performance evaluation and improvement of modern high speed compression ignition engines.
    Źródło:
    Acta Physica Polonica A; 2010, 118, 4; 534-539
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effects of Variable Specific Heat Ratio on Performance οf an Endoreversible Otto Cycle
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1537648.pdf
    Data publikacji:
    2010-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.70.Ln
    82.60.Fa
    88.05.-b
    Opis:
    Using finite-time thermodynamics, the relations between the work output and the compression ratio, between the thermal efficiency and the compression ratio for an endoreversible Otto cycle are derived with variable specific heat ratio of working fluid. The results show that if compression ratio is less than certain value, the increase of specific heat ratio makes the work output and the thermal efficiency higher; on the contrary, if compression ratio exceeds certain value, the increase of specific heat ratio makes the work output and the thermal efficiency less. The results also show that the maximum work output, the compression ratio at the maximum work output point, the working range of the cycle and the compression ratio at maximum thermal efficiency point decrease as the specific heat ratio increased. The results obtained from this work can be helpful in the thermodynamic modeling and in the evaluation of real Otto engines.
    Źródło:
    Acta Physica Polonica A; 2010, 117, 6; 887-891
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Power Optimization of a Miller Thermal Cycle with respect to Residual Gases and Equivalence Ratio
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1399491.pdf
    Data publikacji:
    2013-07
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.70.Ln
    82.60.Fa
    88.05.-b
    88.20.td
    Opis:
    The performance of an air standard Miller cycle is analyzed using finite-time thermodynamics. The relations between the power output and the compression ratio and between the power output and the thermal efficiency are derived by detailed numerical examples. The results show that, throughout the compression ratio range, the power output decreases with increasing residual gases. The results also show that if compression ratio is less than certain value, the power output decreases with increasing equivalence ratio, while if compression ratio exceeds certain value, the power output first increases and then starts to decrease with increasing equivalence ratio. The conclusions of this investigation are of importance when considering the designs of actual Miller engines.
    Źródło:
    Acta Physica Polonica A; 2013, 124, 1; 6-10
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Effects of Equivalence Ratio and Mean Piston Speed on Performance of an Irreversible Dual Cycle
    Autorzy:
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1493377.pdf
    Data publikacji:
    2011-09
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    05.70.Ln
    82.60.Fa
    88.05.-b
    Opis:
    In the present study, the performance of an air standard dual cycle is analyzed using finite-time thermodynamics. The relations between the power output and the compression ratio, between the power output and the thermal efficiency are derived by detailed numerical examples. The results show that the maximum power output and the power output at the maximum efficiency point increase and then decrease as the equivalence ratio and/or the mean piston speed increases. The results also show that the optimal compression ratio corresponding to maximum power output point and the working range of the cycle remain constant as the mean engine speed is increased, but they increase and then decrease as the equivalence ratio is increased. It is noteworthy that the results obtained in the present study are of significance for providing guidance with respect to the performance evaluation of practical internal combustion engines.
    Źródło:
    Acta Physica Polonica A; 2011, 120, 3; 384-389
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Efficiency of CaCl2 spray at different fruit development stages on the fruit mineral nutrient accumulation in cv. Hayward kiwifruit
    Autorzy:
    Shiri, M.A.
    Ghasemnezhad, M.
    Moghadam, J.F.
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/1188065.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
    Tematy:
    Actinidia deliciosa
    fruit
    development stage
    mineral nutrient
    nutrient accumulation
    Hayward cultivar
    kiwi fruit
    calcium absorption
    calcium chloride spray
    Opis:
    Despite the importance of calcium in many fruit species and the effects of calcium application, there is little or no reliable information on the effect of CaCl2 spray at different fruit development stages on the fruit mineral nutrient content during the growing season and at harvest. Therefore, this study has been conducted to evaluate the effect of calcium chloride (CaCl2, 15 g L-1) spray at different fruit development stages on the accumulation Ca and other macronutrients in cv. Hayward kiwifruit grown at two locations. In order to find the absorbality of Ca at different spraying times, fruits were harvested 7 days after a Ca treatment. Additionally, the mineral composition of kwifruit was determined at the stage of harvest ripeness. The results showed that the absorbality of Ca by kiwifruit from Ca spray decreased significantly with the progressing fruit development. The highest fruit Ca content was found when the fruit plants were sprayed at 35+80 DAFB and 35+80+120 DAFB, irrespectively of the location of an orchard. At a later Ca spraying application, the N content in kiwifruit significantly decreased, but the K and Mg content slightly increased. In contrast, the K/Ca, N/Ca, Mg/Ca and (K+Mg)/Ca ratios of CaCl2 sprayed fruits was lower than in the control and the ratio values were more balanced in the Ca treated fruit than in the control. Overall, three CaCl2 (15 g L-1) sprays could effectively improve the fruit quality by balancing the Ca ratio to other macronutrients. Therefore, Ca spray treatments could be a recommended treatment in growing cv. Hayward kiwifruit.
    Źródło:
    Journal of Elementology; 2016, 21, 1; 195-209
    1644-2296
    Pojawia się w:
    Journal of Elementology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Efficiency of CaCl2 spray at different fruit development stages on the fruit mineral nutrient accumulation in cv. Hayward kiwifruit
    Autorzy:
    Shiri, M.A.
    Ghasemnezhad, M.
    Moghadam, J.F.
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/15935.pdf
    Data publikacji:
    2016
    Wydawca:
    Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
    Tematy:
    Actinidia deliciosa
    fruit
    development stage
    mineral nutrient
    nutrient accumulation
    Hayward cultivar
    kiwi fruit
    calcium absorption
    calcium chloride spray
    Opis:
    Despite the importance of calcium in many fruit species and the effects of calcium application, there is little or no reliable information on the effect of CaCl2 spray at different fruit development stages on the fruit mineral nutrient content during the growing season and at harvest. Therefore, this study has been conducted to evaluate the effect of calcium chloride (CaCl2, 15 g L-1) spray at different fruit development stages on the accumulation Ca and other macronutrients in cv. Hayward kiwifruit grown at two locations. In order to find the absorbality of Ca at different spraying times, fruits were harvested 7 days after a Ca treatment. Additionally, the mineral composition of kwifruit was determined at the stage of harvest ripeness. The results showed that the absorbality of Ca by kiwifruit from Ca spray decreased significantly with the progressing fruit development. The highest fruit Ca content was found when the fruit plants were sprayed at 35+80 DAFB and 35+80+120 DAFB, irrespectively of the location of an orchard. At a later Ca spraying application, the N content in kiwifruit significantly decreased, but the K and Mg content slightly increased. In contrast, the K/Ca, N/Ca, Mg/Ca and (K+Mg)/Ca ratios of CaCl2 sprayed fruits was lower than in the control and the ratio values were more balanced in the Ca treated fruit than in the control. Overall, three CaCl2 (15 g L-1) sprays could effectively improve the fruit quality by balancing the Ca ratio to other macronutrients. Therefore, Ca spray treatments could be a recommended treatment in growing cv. Hayward kiwifruit.
    Źródło:
    Journal of Elementology; 2016, 21, 1
    1644-2296
    Pojawia się w:
    Journal of Elementology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    1.25GS/S 12bit and 2.27mW digital to analog converter (DAC) with 70.22 SNDR based on new hybrid R-C procedure in 180nm CMOS
    Autorzy:
    Mahdavi, S.
    Poreh, M.
    Alizadeh, L.
    Moradkhani, B.
    Ebrahimi, R.
    Powiązania:
    https://bibliotekanauki.pl/articles/398146.pdf
    Data publikacji:
    2017
    Wydawca:
    Politechnika Łódzka. Wydział Mikroelektroniki i Informatyki
    Tematy:
    SAR ADC
    DAC
    high-resolution
    power consumption
    high-speed
    wysoka rozdzielczość
    pobór mocy
    Opis:
    This paper presents a novel fully differential high-speed and high-resolution Digital to Analog Converter (DAC) based on new reliable hybrid R-C technique. In the proposed idea the four LSB bits and eight MSB bits are implemented as a resistor string and new merged capacitor technique respectively. Applying the suggested method the SNDR and Effective Number of Bits (ENOB) of the proposed DAC achieve 70.22dB and 11.41 bit at the 1.25GS/s sampling rate correspondingly. In the proposed method the total capacitors of the 8 MSB bits are reduced up to 78% compared to the conventional one noticeably. As a result, the power consumption and speed of the suggested DAC are decreased and increased respectively. Moreover, the total power consumption of the proposed DAC is 2.27mW with the power supply of 1.8 volts as well. Meanwhile, for the correctness of the proposed 12bit DAC, 200 iterations in transient Monte-Carlo analysis (parasitic capacitance included ([symbol] mismatch = 1.2%)), and the SNDR simulation results versus different input frequency at fS=1.25GS/s sampling rate are applied too. The maximum Integral Nonlinearity (INL) and the maximum Differential Nonlinearity (DNL) are -0.47/+0.35LSB and -0.42/+0.29 LSB respectively. The proposed DAC structure is simulated in all process corners and performed using the HSPICE BSIM3 model of a 0.18μm CMOS technology.
    Źródło:
    International Journal of Microelectronics and Computer Science; 2017, 8, 4; 127-132
    2080-8755
    2353-9607
    Pojawia się w:
    International Journal of Microelectronics and Computer Science
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Fabrication of Open Cell Fe-10%Al Foam by Space-Holder Technique
    Wytwarzanie piany Fe-10%Al o otwartej porowatości metodą wypełniacza przestrzeni
    Autorzy:
    Golabgir, M. H.
    Ebrahimi-Kahrizsangi, R.
    Torabi, O.
    Saatchi, S.
    Powiązania:
    https://bibliotekanauki.pl/articles/356297.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    open-celled foam
    Fe-Al alloy
    mechanical alloying
    metal foam
    space-holder
    wypełniacz przestrzeni piany
    stop Fe-Al
    stopowanie mechaniczne
    porowatość
    Opis:
    In this paper, fabrication of open-celled porous Fe-10%A1 foam by space-holder technique in which NaCl powder and polyester resin were utilized as space holder and binder respectively to generate 30-80% porosities was studied. FeAl solid solution was prepared via mechanical alloying method after 25 h high energy milling process. The results indicate that the size and shapes of the pores are determined by the size and shapes of NaCl particles. Also, when compaction pressure was in the range of 70-150 MPa and the sintering process was performed at temperature around 1100°C, the samples had the best quality. Microstructure observations show the pore size was in the range of 200-500 μm.
    W niniejszej pracy badano wytwarzanie techniką wypełniacza przestrzeni piany Fe-10%Al o otwartej porowatości, w której proszek NaCl i Żywicę poliestrową wykorzystano odpowiednio w roli wypełniacza porów i spoiwa do wytworzenia piany o 30-80% porowatości. Roztwór stały FeAl został wytworzony poprzez mechaniczne stopowanie przez 25 h w trakcie wysokoenergetycznego mielenia. Wyniki wskazują, że rozmiar i kształt porów determinowany jest przez wielkość i kształt cząstek NaCl. Ponadto, gdy ciśnienie prasowania było w zakresie 70-150 MPa a proces spiekania prowadzono w temperaturze około 1100°C. próbki miały najwyższą jakość. Obserwacje mikrostruktury wykazały, że rozmiar porów mieścił się w zakresie 200-500 μm.
    Źródło:
    Archives of Metallurgy and Materials; 2014, 59, 1; 41-45
    1733-3490
    Pojawia się w:
    Archives of Metallurgy and Materials
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Molecular characterization of Theileria equi infection in horse populations belonging to West Azerbaijan, Iran: insights into the importance of Equine Merozoite Antigen (EMA)-1 in its diagnosis
    Autorzy:
    Ebrahimi, M.
    Adinehbeigi, K.
    Hamidinejat, H.
    Tabandeh, M.R.
    Powiązania:
    https://bibliotekanauki.pl/articles/6114.pdf
    Data publikacji:
    2018
    Wydawca:
    Polskie Towarzystwo Parazytologiczne
    Źródło:
    Annals of Parasitology; 2018, 64, 1
    0043-5163
    Pojawia się w:
    Annals of Parasitology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Determining the structural amino acid attributes which are important in both protein thermostability and alkalophilicity: a case study on xylanase
    Autorzy:
    Delavari, A.
    Zare, S.
    Ghaemi, M.R.
    Kashfi, R.
    Ebrahimi, M.
    Tahmasebi, A.
    Ebrahimie, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/80216.pdf
    Data publikacji:
    2014
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    amino acid
    xylanase
    hemicellulose
    thermostability
    linear regression
    bioinformatics
    Źródło:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2014, 95, 2
    0860-7796
    Pojawia się w:
    BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-14 z 14

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