Artykuły w czasopismach: „CASCADE CYCLE”

1

Woodward, John B. "The Rankine Topping Cycle Revisited". Journal of Ship Research 36, nr 01 (1.03.1992): 91–98. http://dx.doi.org/10.5957/jsr.1992.36.1.91.

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Cascaded thermodynamic machines are familiar in marine engineering, even if the word "cascade" is not common currency in that field. The author refers to the almost universal practice of exhausting the working fluid (air) of a diesel engine into a gas turbine (the turbocharger, usually), followed by exhausting of that working fluid into a heat exchanger that energizes the working fluid (water) of yet another turbine. If the same practice is to be described in terms of the respective power cycles, we would probably say that the cascade consists of a Rankine cycle topped by a Brayton cycle which is in turn topped by a diesel cycle. In similar fashion, recognized nomenclature might describe the diesel component as the "topping cycle," and the Rankine as the "bottoming cycle." The topping/bottoming nomenclature usually implies two different working fluids, so that the Brayton cycle might be described as a subpart of the topping cycle.

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2

Lee, Ho Saeng, S. T. Oh, Jung In Yoon, S. G. Lee i K. H. Choi. "Analysis of Cryogenic Refrigeration Cycle Using Two Stage Intercooler". Defect and Diffusion Forum 297-301 (kwiecień 2010): 1146–51. http://dx.doi.org/10.4028/www.scientific.net/ddf.297-301.1146.

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This paper presents the comparison of performance characteristics for the several natural gas liquefaction cycles. The liquefaction cycle with the staged compression was designed and simulated for improving the cycle efficiency using HYSYS software. This includes a cascade cycle with a two-stage intercooler which is consisted of a Propane, Ethylene and Methane cycle. In addition, these cycles are compared with a modified staged compression process. The key parameters of the above cascade cycles were compared and analyzed. The COP (Coefficient of Performance) of the cascade cycle with a two-stage intercooler and a modified staged compression process is 13.7% and 29.7% higher than that of basic cycle. Also, the yield efficiency of LNG (Liquefied Natural Gas) improved compared with the basic cycle by 28.5%.

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3

Fu, Lan Fang, He Xu Sun i Yan Cai Zhu. "Sample Time Staggered One-Cycle Control Based on Three-Phase H-Bridge Cascade VSI". Advanced Materials Research 516-517 (maj 2012): 1822–26. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.1822.

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The One-Cycle Control(OCC) technique not only provides fast dynamic response, but also can admirably suppress the perturbation yielded by dc source and eliminate the undesired harmonic contents.The cascade H-bridge VSI has very low dv/dt and distortion in the voltage output waveform.Sample time staggered one-cycle control（STS-OCC） based on three-phase H-bridge cascade VSI is proposed. It yields all of the advantages of the OCC and cascade VSI.The results of the simulation and analysis show that the STS-OCC technology has high equivalent work frequency, little switching loss and quick dynamic response speed, which means it is fit for the cascaded multilevel inverter.

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4

Yao, Shouguang, Likang Xu i Liang Tang. "New cold-level utilization scheme for cascade three-level rankine cycle using the cold energy of liquefied natural gas". Thermal Science 23, nr 6 Part B (2019): 3865–75. http://dx.doi.org/10.2298/tsci171012239y.

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The topic of this study is the intermediate fluid vaporizer gasification system for a liquefied natural gas floating storage regasification unit. To reduce the loss of heat exchange, the primary distributary cascade three-level Rankine cycle is optimised based on the cascade three-level Rankine cycle that uses the cold energy of liquefied natural gas to generate power. The optimized primary distributary cascade three-level Rankine cycle is then compared with the original cascade three Rankine cycle established under the same conditions. Then, a secondary distributary cascade three-level Rankine cycle is proposed. Results show that under a liquefied natural gas flow of 175 t/h, the primary distributary cascade three-level Rankine cycle system exhibits a maximum net output power of 4130.72 kW and an exergy efficiency of 23.78%, which is higher than that of the typical cascade three-level Rankine cycle. Moreover, the net output power and exergy efficiency of the primary distributary cascade three-level Rankine cycle system increased by 3.71% and by 3.84%, respectively. The secondary distributary cascade three-level Rankine cycle system exhibits a maximum net output power of 4143.75 kW and an exergy efficiency of 23.85%.

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5

Xu, Likang, i Guihua Lin. "Simulation and optimization of liquefied natural gas cold energy power generation system on floating storage and regasification unit". Thermal Science, nr 00 (2020): 205. http://dx.doi.org/10.2298/tsci200404205x.

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In this paper, based on the idea of reducing heat exchanger exergy destruction and increasing turbine work, a new three-stage cascade Rankine system and a new four-stage cascade Rankine system is proposed to improve the cold energy utilization rate during liquefied natural gas(LNG) gasification on liquefied natural gas-floating storage and regasification unit. Then compare them with the original cascade Rankine cycle established under the same conditions. The results show that under the condition of 175 t/h LNG flow, the maximum net output power of the new three-stage cascade Rankine cycle system is 4593.31 kW, the exergy efficiency is 20.644%. The maximum net output power of the new four-stage cascade Rankine cycle system is 5013.93 kW, and the exergy efficiency is 22.509%. Compared with the original cascade Rankine cycle system, the maximum net output power of the new three-stage cascade Rankine cycle system and the new four-stage cascade Rankine cycle system is increased by 9.41% and 11.45%, respectively, and the system exergy efficiency is increased by 9.29% and 11.28%, respectively.

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6

Sun, Heng, Hong Mei Zhu i Hong Wei Liu. "Process Simulations of the Cold Recovery Unit in a LNG CCHP System with Different Power Cycles". Applied Mechanics and Materials 90-93 (wrzesień 2011): 3026–32. http://dx.doi.org/10.4028/www.scientific.net/amm.90-93.3026.

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A CCHP system using LNG as the primary energy should integrate cold recovery unit to increase the total energy efficiency. A scheme of CCHP consisting of gas turbine-steam turbine combined cycle, absorption refrigeration unit, cold recovery unit and cooling media system is a system with high efficiency and operation flexibility. Three different power cycles using the cold energy of LNG is(are 或 were) presented and simulated. The results show that the cascade Rankine power cycle using ethylene and propane in the two cycles respectively has highest energy efficiency. However, the unit is most complex. The efficiency of ethylene Rankine power cycle is little lower than the cascade one, and is much higher than the traditional propane Rankine cycle. The complexity of ethylene cycle is identical to that of the propane cycle. The ethylene Rankine power cycle is the referred method of cold recovery in a CCHP system based on overall considerations.

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7

Rehberger, Max, i Michael Hiete. "Allocation Procedures for Generic Cascade Use Cases - An Evaluation Using Monte Carlo Analysis". Materials Science Forum 959 (czerwiec 2019): 32–45. http://dx.doi.org/10.4028/www.scientific.net/msf.959.32.

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Cascade use - a concept for increasing resource efficiency by multiple use of resources - gains in importance, in particular for bio-based materials. Allocation of environmental burdens and costs along the cascade chain plays a major role in deciding whether to establish a cascade or not. This highlights the need for a methodology for properly assessing different types of cascades. To provide guidance in terms of choice of allocation procedure available from life cycle assessment (LCA), Monte Carlo analysis is used. Especially hybrid, individually tailored allocation approaches can be evaluated in this way. The results show a high diversity of possible outcomes in terms of general allocation intensity (how much burden is shifted between steps of the cascade), rank reversals (exchange of positions inside the burden ranking) and variance of the overall results of the cascade allocation. Results are valuable for selecting an allocation procedure for cascade LCA and for further interpreting cascade models using specific allocation procedures.

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8

ROH, CHUL WOO, JIN WOO YOO i MIN SOO KIM. "VAPOR REFRIGERANT INJECTION TECHNIQUES FOR HEAT PUMP SYSTEMS: THE LATEST LITERATURE REVIEW AND DISCUSSION". International Journal of Air-Conditioning and Refrigeration 22, nr 01 (marzec 2014): 1430002. http://dx.doi.org/10.1142/s201013251430002x.

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This paper reviews the latest and major research on vapor refrigerant injection techniques. Various vapor refrigerant injection techniques are discussed and compared. Compared to the basic vapor injection (VI) cycle, double-expansion VI cycle, accumulator-VI cycle and the VI cycle in a cascade system are briefly explained. Studies about these various VI cycles do not only prove the performance of VI cycles, but also show variations of VI cycles. Discussions about the fundamental issues of the VI cycle are also presented.

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9

Boahen i Choi. "A Study on the Performance of a Cascade Heat Pump for Generating Hot Water". Energies 12, nr 22 (12.11.2019): 4313. http://dx.doi.org/10.3390/en12224313.

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The use of cascade heat pumps for hot water generation has gained much attention in recent times. The big question that has attracted much research interest is how to enhance the performance and energy saving potential of these cascade heat pumps. This study therefore proposed a new cycle to enhance performance of the cascade heat pump by adopting an auxiliary heat exchanger (AHX) in desuperheater, heater and parallel positions at the low stage (LS) side. The new cascade cycle with AHX in desuperheater position was found to have better performance than that with AHX at heater and parallel positions. Compared to the conventional cycle, heating capacity and coefficient of performance (COP) of the new cascade cycle with AHX in desuperheater position increased up to 7.4% and 14.9% respectively.

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10

Wu, Chih. "Power performance of a cascade endoreversible cycle". Energy Conversion and Management 30, nr 3 (styczeń 1990): 261–66. http://dx.doi.org/10.1016/0196-8904(90)90008-m.

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11

Jankovich, Dennis, i Kresimir Osman. "A feasibility analysis of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry". Thermal Science 19, nr 5 (2015): 1821–33. http://dx.doi.org/10.2298/tsci130611097j.

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The thermodynamic analysis demonstrates the feasibility of replacing the standard ammonia refrigeration device with the cascade NH3/CO2 refrigeration device in the food industry. The main reason for replacement is to reduce the total amount of ammonia in spaces like deep-freezing chambers, daily chambers, working rooms and technical passageways. An ammonia-contaminated area is hazardous to human health and the safety of food products. Therefore the preferred reduced amount of ammonia is accumulated in the Central Refrigeration Engine Room, where the cascade NH3/CO2 device is installed as well. Furthermore, the analysis discusses and compares two left Carnot?s refrigeration cycles, one for the standard ammonia device and the other for the cascade NH3/CO2 device. Both cycles are processes with two-stage compression and two-stage throttling. The thermodynamic analysis demonstrates that the selected refrigeration cycle is the most cost-effective process because it provides the best numerical values for the total refrigeration factor with respect to the observed refrigeration cycle. The chief analyzed influential parameters of the cascade device are: total refrigeration load, total reactive power, mean temperature of the heat exchanger, evaporating and condensing temperature of the low-temperature part.

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12

Zhu, Hong Mei, Hong Wei Liu i Heng Sun. "Exergy Analysis of Cascade Ethylene-Propane Rankine Cycle with Cold Energy Recovery of LNG". Applied Mechanics and Materials 170-173 (maj 2012): 2489–93. http://dx.doi.org/10.4028/www.scientific.net/amm.170-173.2489.

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Cascade Rankine power cycle is suitable for cold recovery in a CCHP system which uses LNG as the primary energy. It has the advantages of low operating pressure and high energy efficiency. Exergy analysis of a typical cascade ethylene-propane Rankine power cycle is conducted. The results show that the exergy losses mainly occur in the low temperature part of the cycle. The exergy loss in the LNG-ethylene heat exchanger could reach about 46% of the total exergy loss. Therefore, the reduction of the exergy losses in the low temperature is important for the improvement of the performance of cascade power cycle.

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13

Atasbak, Musa, Arzu Keven i Rabi Karaali. "Exergy analyses of two and three stage cryogenic cycles". Applied Rheology 32, nr 1 (1.01.2022): 190–204. http://dx.doi.org/10.1515/arh-2022-0134.

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Abstract Cryogenics has an important influence on industry and science. In this study, optimum working conditions are obtained by applying exergy analysis and local optimization methods to two- and three-stage vapor compression cascade cryogenic cycle. The first and second laws of thermodynamics, exergy analysis, and local optimization methods are applied to the two- and three-stage cascade cryogenic cycle. By considering the needs and demands, it is possible to create new cycles by adding new devices and/or new stages to these cycles. The results of the optimum operating conditions are obtained for the two- and three-stage vapor compression cascade cryogenic cycle. It is seen that to achieve high COP values and high efficiency; it is necessary to reduce the compression ratio of the compressor as much as the fluid allows. For the two-stage cycle, the minimum total work required for cryogenic cooling is around P 7 = 2,400 kPa. The COP value is 0.30 between P 7 = 2,400 and 2,800 kPa, and the maximum exergy efficiency is obtained around 0.235. It is seen operating the first-stage compressor at high pressures increases the total losses of the entire cycle from 7,500 to 18,550 kW. The increase in total exergy losses is around 247%, and operating the first-stage compressor at high pressures increases the exergy efficiency of the entire cycle. The increase in total exergy efficiency is around 160%. When the second-stage compressor is operated at low pressure, the COP value increases by 2%, the exergy efficiency increases by 20%, and the exergy losses decrease by around 40%.

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14

Iwamori, Naoki, Kunihiko Naito, Koji Sugiura, Hideyuki Kagii, Masakane Yamashita, Satoshi Ohashi, Seitaro Goto, Keitaro Yamanouchi i Hideaki Tojo. "Phosphorylation of mitogen-activated protein kinase cascade during early embryo development in the mouse". Reproduction, Fertility and Development 12, nr 4 (2000): 209. http://dx.doi.org/10.1071/rd00064.

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The mitogen-activated protein kinase (MAPK) cascade is one of the most important signal transduction pathways that regulate the cell cycle in somatic cells. The present study examined the phosphorylation states of components in the MAPK cascade, Raf-1, MEK-1, and extracellular signal regulated kinases (ERKs), which are activated by mitogens, throughout early mouse embryo development and in cultured somatic cells generally. In somatic cells, Raf-1 and MEK-1 were phosphorylated at M-phase and dephosphorylated during interphase. ERKs were not phosphorylated at any stage during the cell cycle. These results were similar to previous findings for the first and second cell cycles of early mouse embryos. In contrast, after the four-cell stage, not only ERKs, but also Raf-1 and MEK-1, were not phosphorylated at any stage during the cell cycle in mouse early embryos. These results suggest that the MAPK cascade in mouse embryos is regulated by the same mechanism as in somatic cells before the two-cell stage, and that regulation is changed to an embryo-specific mechanism after the four-cell stage.

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Cimarelli, A., E. De Angelis, J. Jiménez i C. M. Casciola. "Cascades and wall-normal fluxes in turbulent channel flows". Journal of Fluid Mechanics 796 (4.05.2016): 417–36. http://dx.doi.org/10.1017/jfm.2016.275.

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The present work describes the multidimensional behaviour of scale-energy production, transfer and dissipation in wall-bounded turbulent flows. This approach allows us to understand the cascade mechanisms by which scale energy is transmitted scale-by-scale among different regions of the flow. Two driving mechanisms are identified. A strong scale-energy source in the buffer layer related to the near-wall cycle and an outer scale-energy source associated with an outer turbulent cycle in the overlap layer. These two sourcing mechanisms lead to a complex redistribution of scale energy where spatially evolving reverse and forward cascades coexist. From a hierarchy of spanwise scales in the near-wall region generated through a reverse cascade and local turbulent generation processes, scale energy is transferred towards the bulk, flowing through the attached scales of motion, while among the detached scales it converges towards small scales, still ascending towards the channel centre. The attached scales of wall-bounded turbulence are then recognized to sustain a spatial reverse cascade process towards the bulk flow. On the other hand, the detached scales are involved in a direct forward cascade process that links the scale-energy excess at large attached scales with dissipation at the smaller scales of motion located further away from the wall. The unexpected behaviour of the fluxes and of the turbulent generation mechanisms may have strong repercussions on both theoretical and modelling approaches to wall turbulence. Indeed, actual turbulent flows are shown here to have a much richer physics with respect to the classical notion of turbulent cascade, where anisotropic production and inhomogeneous fluxes lead to a complex redistribution of energy where a spatial reverse cascade plays a central role.

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16

Gustin, Michael C., Jacobus Albertyn, Matthew Alexander i Kenneth Davenport. "MAP Kinase Pathways in the YeastSaccharomyces cerevisiae". Microbiology and Molecular Biology Reviews 62, nr 4 (1.12.1998): 1264–300. http://dx.doi.org/10.1128/mmbr.62.4.1264-1300.1998.

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SUMMARY A cascade of three protein kinases known as a mitogen-activated protein kinase (MAPK) cascade is commonly found as part of the signaling pathways in eukaryotic cells. Almost two decades of genetic and biochemical experimentation plus the recently completed DNA sequence of the Saccharomyces cerevisiae genome have revealed just five functionally distinct MAPK cascades in this yeast. Sexual conjugation, cell growth, and adaptation to stress, for example, all require MAPK-mediated cellular responses. A primary function of these cascades appears to be the regulation of gene expression in response to extracellular signals or as part of specific developmental processes. In addition, the MAPK cascades often appear to regulate the cell cycle and vice versa. Despite the success of the gene hunter era in revealing these pathways, there are still many significant gaps in our knowledge of the molecular mechanisms for activation of these cascades and how the cascades regulate cell function. For example, comparison of different yeast signaling pathways reveals a surprising variety of different types of upstream signaling proteins that function to activate a MAPK cascade, yet how the upstream proteins actually activate the cascade remains unclear. We also know that the yeast MAPK pathways regulate each other and interact with other signaling pathways to produce a coordinated pattern of gene expression, but the molecular mechanisms of this cross talk are poorly understood. This review is therefore an attempt to present the current knowledge of MAPK pathways in yeast and some directions for future research in this area.

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17

Yang, Yong An, Zhao Yang i Qiu Bo Xu. "Research on the Auto Cascade Refrigerating Cycle System". Advanced Materials Research 516-517 (maj 2012): 1128–32. http://dx.doi.org/10.4028/www.scientific.net/amr.516-517.1128.

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An auto cascade refrigerating cycle system was built up in the laboratory. By changing the parameters of the operation process, the law of the operation and the effect on performance of the system were studied. When the extrinsic parameters changed, the performances of the system were measured. The paper analyzed that the evaporation temperature and the temperature of the inlet of the cooling water affect on the efficiency of the system and the pressure rate. The result shows that when the temperature of the cooling water is given, the COP of the system goes down with the decrease of the evaporation temperature. And when the evaporation temperature is given, the COP of system goes down with the increase of the condensate temperature. The pressure rate increases when the temperature of the cooling water gets higher. When both the evaporation temperature and the temperature of the cooling water are given, the COP of a R22/R23 system is higher than that of an R134a/R23 system.

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Li, Hongjun, Ze Zhou, Chaobo Li i Shibing Zhang. "RCCM: Reinforce Cycle Cascade Model for Image Recognition". IEEE Access 8 (2020): 15369–76. http://dx.doi.org/10.1109/access.2020.2966667.

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Zhou, Hao, Ping Zou, Zhi-chao Chen i Yong You. "A novel vicious cycle cascade in tumor chemotherapy". Medical Hypotheses 69, nr 6 (styczeń 2007): 1230–33. http://dx.doi.org/10.1016/j.mehy.2007.03.038.

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Chen, Guangming, Volodymyr Ierin, Oleksii Volovyk i Kostyantyn Shestopalov. "An improved cascade mechanical compression–ejector cooling cycle". Energy 170 (marzec 2019): 459–70. http://dx.doi.org/10.1016/j.energy.2018.12.107.

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Pinheiro Ferreira, Vitor, Micael Lima Conceição i William Souza dos Santos. "EXPERIMENTAL EVALUATION OF A CASCADE REFRIGERATION SYSTEM USING R-134a AND R-404a". RECIMA21 - Revista Científica Multidisciplinar - ISSN 2675-6218 3, nr 2 (7.02.2022): e321127. http://dx.doi.org/10.47820/recima21.v3i2.1127.

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Cascade refrigeration system is an attractive technology for low-temperature requirement, allowing operation under these conditions with positive suction pressures and a moderate condensation pressure at ambient temperature. This work describes a performance analysis of a cascade refrigeration prototype equipped with hermetic compressors working with R-134a and R-404a as refrigerants, thermally connected by a tube-in-tube-type cascade-condenser. Energy flows and performance parameters were evaluated under different evaporating temperature conditions of the low temperature cycle (LTC). The results showed an increase in energy efficiency ratio (EER) and coefficients of performance (COP) of cascade system as well as of each cycle with the increase of LTC evaporating temperature, even with a simultaneous increase of temperature difference in cascade-condenser.

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Xiao, Jian, i Ying Fu Liu. "Entropy Analysis of a R32/CO₂ Cascade Refrigeration Cycle". Applied Mechanics and Materials 672-674 (październik 2014): 1676–79. http://dx.doi.org/10.4028/www.scientific.net/amm.672-674.1676.

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In order to study the performance of a R32/CO2 cascade refrigeration cycle, entropy generation minimization method was adopted to get the influence of some important operating and design parameters on the performance of the system and entropy generations of each component and the whole system, such as the evaporating temperature(Te), the condensing temperature(Tk) and the temperature difference in the cascade condenser(ΔT). The results indicate that there are a maximum COP and a minimum total entropy generation of the system at the optimal condensing temperature of the cascade condenser when Te, Tk and ΔT are constant. The total entropy generations of the throttling device, the condenser and the compressor of HTC, the cascade condenser and the compressor of LTC are above 80% of the total entropy generation of the whole system.

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Zheng, Da Yu, Dan Li, Jia Zheng, Li Ping Gao i Yi Ming Zhang. "The Study of the Effects of Refrigerant Fraction on Auto-Cascade Refrigeration System of Evaporation Temperature". Advanced Materials Research 889-890 (luty 2014): 321–24. http://dx.doi.org/10.4028/www.scientific.net/amr.889-890.321.

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Non-azeotropic auto-cascade refrigeration system utilizes various components of different boiling refrigerant to get low-temperature. With R22, R23 and R14 as a non-azeotropic refrigerant auto-cascade refrigeration cycle system. Through the experimental study of non-azeotropic refrigerant charging and the ratio between the amount of charge, to analyze the effect of these three refrigerants charging and relationship of the fraction on the whole refrigeration cycle refrigeration temperature. To improve overall non-azeotropic auto-cascade refrigeration systems working efficiency. So as to achieve the purpose of energy saving.

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Hake, Leander, Felix Reinker, Robert Wagner, Stefan aus der Wiesche i Markus Schatz. "The Profile Loss of Additive Manufactured Blades for Organic Rankine Cycle Turbines". International Journal of Turbomachinery, Propulsion and Power 7, nr 1 (21.03.2022): 11. http://dx.doi.org/10.3390/ijtpp7010011.

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Results from an experimental profile loss study are presented of an additive manufactured linear turbine cascade placed in the test section of a closed-loop organic vapor wind tunnel. This test facility at Muenster University of Applied Sciences allows the investigation of high subsonic and transonic organic vapor flows under ORC turbine flow conditions at elevated pressure and temperature levels. An airfoil from the open literature was chosen for the cascade, and the organic vapor was Novec 649TM. Pitot probes measured the flow field upstream and downstream of the cascade. The inflow turbulence level was 0.5%. The roughness parameters of the metal-printed blades were determined, and the first set of flow measurements was performed. Then, the blade surfaces were further finished, and the impact of roughness on profile losses was assessed in the second flow measurement set. Although the Reynolds number level was relatively high, further surface treatment reduces the profile loss noticeably in organic vapor flows through the printed cascade.

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Liu, Zhenzhen, Jingde Jiang, Zilong Wang i Hua Zhang. "Thermodynamic Analysis of an Innovative Cold Energy Storage System for Auto-Cascade Refrigeration Applications". Energies 16, nr 5 (27.02.2023): 2282. http://dx.doi.org/10.3390/en16052282.

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The cooling capacity needed by ultra-low temperature apparatus cannot be reached economically with a single vapor compression refrigeration cycle due to the constraint of the high compressor pressure ratio. The auto-cascade refrigeration cycle is a good alternative. In this work, a novel concept that applies the principle of the auto-cascade refrigeration cycle to store cold energy is conducted. The environment-friendly refrigerants of R600a/R290/R170 zeotropic mixtures are used to study the performance of the modified auto-cascade refrigeration cycle (MACRC) as an alternative for cold-energy applications. The simulation results show that a cooling capacity of 500 W can be provided below −60 °C. The mixture with a mass fraction of 0.25/0.35/0.40 yields a COP of 0.695 and an exergy efficiency of 0.262 at −66 °C. The performance of the MACRC system was investigated at an ambient temperature of 20 to 40 °C for indoor small-scale applications. It is concluded that the performance would be improved by decreasing the ambient temperature. The results of the work should be helpful for the design and optimization of auto-cascade systems.

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Wang, Lin, Xiao Long Cui, Ying Ying Tan i Yu Wang. "Study on Energy Efficiency of a Low Temperature Refrigeration System". Applied Mechanics and Materials 71-78 (lipiec 2011): 292–95. http://dx.doi.org/10.4028/www.scientific.net/amm.71-78.292.

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Based on conservation of mass, total mass balance equation and component mass balance equation, mathematical models of thermodynamic for the auto cascade refrigeration cycle are established. Thermophysical properties in solving the governing equation are called from the NIST REFPROP7.0. Thermodynamic properties of the auto cascade refrigeration cycle using binary mixtures, namely, R170/R290, R23/R227ea, R116/R134a, R23/R134a, R170/R600a, R170/R600 and R170/R152a as refrigerants is evaluated. R170/R600a is selected for the low temperature refrigeration system, and the influences of cycle mole fraction, compression ratio and evaporating pressure on the cycle performance are analysed.

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Bai, Fang, Hongsheng Ding, Lige Tong, Liqing Pan i Li Wang. "Microstructural Changes and Impact Toughness of Fill Pass in X80 Steel Weld Metal". Metals 9, nr 8 (16.08.2019): 898. http://dx.doi.org/10.3390/met9080898.

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Multi-pass welding is used in high-pressure and thick-walled pipes in natural gas and oil pipelines. When a welding layer of a welded joint is subjected to different welding thermal cycles, its microstructure and properties change, thereby affecting the overall welding performance. In this study, the temperature and microstructural variations of the fill pass 2 (FP2) in the entire welding process were investigated by combining the thermal cycle with the cascade welding method. The original FP2 and FP2 after double thermal cycles had the worse deformation ability by tensile test. The toughness of FP2 improved after a single thermal cycle, decreased after double thermal cycles, and improved again after triple thermal cycles. The content of martensite–austenite (M–A) constituents and the average grain size of FP2 in the cascade samples were inversely proportional to FP2 toughness. Massive M–A constituents and their unique distribution at the inter-critical temperature were harmful to weld metal toughness. Controlling the size and fraction of M–A constituents can improve weld metal toughness.

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Nizimov, V., D. Chugunov i K. Dekhtyar. "APPLICATION OF RECEIVABLE DYNAMIC BRAKING TO INCREASE THE PRODUCTIVITY OF A LIFTING SKIP INSTALLATION". Collection of scholarly papers of Dniprovsk State Technical University (Technical Sciences) 2, nr 41 (19.12.2022): 98–106. http://dx.doi.org/10.31319/2519-2884.41.2022.11.

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The work solves an actual technical problem — increasing the productivity of the mine skip installation by shifting the lift cycle of the skip loading. The aim of the work is to provide a theoretical and experimental study of the electric drive according to the scheme of the asynchronous valve cascade (AVK) to reduce the cycle time of the lifting skip installation. The task of the work is the development of an economical electric drive according to the scheme of an asynchronous valve cascade for mine skip lifting installations. To increase the productivity of the lifting installation, an automated electric drive according to the scheme of an asynchronous valve cascade is proposed. Calculated and constructed static and mechanical characteristics of the cascade for engine and regenerative braking modes. The structural diagram of the cascade is given, on the basis of which the speed diagram is constructed. Industrial tests of the electric drive according to the cascade scheme were carried out on an operating mine skip unit. It is proven that the proposed scheme will ensure a reduction in the lifting cycle time of the skip installation and an increase in productivity by 3...5 %. The developed electric drive system is recommended for the modernization of existing mine skip lifting installations equipped with a relay-contactor control scheme.

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Manfredi, Marco, Andrea Spinelli, Giacomo Persico, Paolo Gaetani i Vinenzo Dossena. "Nitrogen Experiments on a Supersonic Linear Cascade For ORC Applications". Journal of Physics: Conference Series 2511, nr 1 (1.05.2023): 012022. http://dx.doi.org/10.1088/1742-6596/2511/1/012022.

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Abstract A novel experiment has been conceived at Politecnico di Milano for the study of the flow within and downstream of supersonic cascades of Organic Rankine Cycle (ORC) turbines. This paper documents the first phase of the research, focused on the preliminary tests and studies performed by operating the facility with nitrogen as working fluid, to demonstrate the technical relevance of the experiment and the validity of the measurement system in a simplified thermodynamic condition. The set of measured data includes, beside the inlet total thermodynamic state, eight static pressure values obtained via taps manufactured on the test section rear end-wall, both within the bladed and semi-bladed region of the cascade, as well as a total pressure probe to retrieve the cascade performance. A double-passage Schlieren equipment was also employed to visualize the density gradients. Experiments show an outstanding repeatability, indicate a quasi-steady cascade operation during the blow-down process for all the pressure signal considered, and demonstrate a remarkable periodicity among two consecutive channels also in off-design conditions. Experimental data were also compared with CFD simulations, resulting in an excellent agreement for the pressure data acquired both within and downstream of the cascade.

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Stuecker, Malte F., Fei-Fei Jin i Axel Timmermann. "El Niño−Southern Oscillation frequency cascade". Proceedings of the National Academy of Sciences 112, nr 44 (19.10.2015): 13490–95. http://dx.doi.org/10.1073/pnas.1508622112.

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The El Niño−Southern Oscillation (ENSO) phenomenon, the most pronounced feature of internally generated climate variability, occurs on interannual timescales and impacts the global climate system through an interaction with the annual cycle. The tight coupling between ENSO and the annual cycle is particularly pronounced over the tropical Western Pacific. Here we show that this nonlinear interaction results in a frequency cascade in the atmospheric circulation, which is characterized by deterministic high-frequency variability on near-annual and subannual timescales. Through climate model experiments and observational analysis, it is documented that a substantial fraction of the anomalous Northwest Pacific anticyclone variability, which is the main atmospheric link between ENSO and the East Asian Monsoon system, can be explained by these interactions and is thus deterministic and potentially predictable.

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Parundekar, Akshay, i Ganesh A. Viswanathan. "Retroactivity induced operating regime transition in an enzymatic futile cycle". PLOS ONE 16, nr 4 (30.04.2021): e0250830. http://dx.doi.org/10.1371/journal.pone.0250830.

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Activated phosphorylation-dephosphorylation biochemical reaction cycles are a class of enzymatic futile cycles. A futile cycle such as a single MAPK cascade governed by two underlying enzymatic reactions permits Hyperbolic (H), Signal transducing (ST), Threshold-hyperbolic (TH) and Ultrasensitive (U) operating regimes that characterize input-output behaviour. Retroactive signalling caused by load due to sequestration of phosphorylated or unphosphorylated form of the substrate in a single enzymatic cascade without explicit feedback can introduce two-way communication, a feature not possible otherwise. We systematically characterize the operating regimes of a futile cycle subject to retroactivity in either of the substrate forms. We demonstrate that increasing retroactivity strength, which quantifies the downstream load, can trigger five possible regime transitions. Retroactivity strength is a reflection of the fraction of the substrate sequestered by its downstream target. Remarkably, the minimum required retroactivity strength to evidence any sequestration triggered regime transition demands 23% of the substrate bound to its downstream target. This minimum retroactivity strength corresponds to the transition of the dose-response curve from ST to H regime. We show that modulation of the saturation and unsaturation levels of the enzymatic reactions by retroactivity is the fundamental mechanism governing operating regime transition.

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Jang, Sung, i Young Lee. "Experimental study on cascade heat pump dryer with a solar collector under low temperature outdoor air environment". Thermal Science 22, nr 2 (2018): 993–1001. http://dx.doi.org/10.2298/tsci160811086j.

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A heat pump dryer can save more energy than other dryers since its drying efficiency is 2-3 times higher than that of other types of dryers. However, the lower bound of evaporating temperature for an R134a heat pump cycle ranges from 5 to 10?C, when the outdoor air temperature closely approaches the evaporating temperature, it experiences reduced efficiency and ultimately becomes inoperable. To address this issue, a cascade heat pump dryer equipped with a solar collector was considered in order to examine the operability and efficiency of the heat pump cycle, depending on changes in the outdoor air temperature in wintertime. The changes in cascade cycles, depending on the temperature in a drying chamber, were also observed. The results showed that the average coefficient of performance (COP) of the cascade heat pump dryer was approximately 2.6 under the temperature range of ?10 to 20 ?C. An electrical heater whose COP is less than one should be used in that temperature range. It was also found that COP of the dryer increased by approximately 35% when using a solar collector under a low outdoor air temperature environment.

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33

Zhu, Hong Mei, Heng Sun i Hong Wei Liu. "Parameters Analysis of a Cascade Ethylene-Propane Rankine Cycle with Cold Energy Recovery of LNG". Advanced Materials Research 446-449 (styczeń 2012): 2895–99. http://dx.doi.org/10.4028/www.scientific.net/amr.446-449.2895.

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A cascade ethylene-propane Rankine power cycle that can recover LNG’s cold energy is represented. It is rather appreciated for a CCHP system which uses LNG as the primary energy due to the relatively low operating pressure of the cascade system. The parameter analysis is done for the key process parameters which mainly affect the performance of the system. The results show that the performance can be improved by decreasing the low pressure of the ethylene cycle and increasing the high pressure of the propane cycle. The optimized parameters can obtain 7.43% more electric power and 2.4% more cooling energy.

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Yu, Xiaoli, Zhi Li, Yiji Lu, Rui Huang i Anthony Roskilly. "Investigation of an Innovative Cascade Cycle Combining a Trilateral Cycle and an Organic Rankine Cycle (TLC-ORC) for Industry or Transport Application". Energies 11, nr 11 (5.11.2018): 3032. http://dx.doi.org/10.3390/en11113032.

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An innovative cascade cycle combining a trilateral cycle and an organic Rankine cycle (TLC-ORC) system is proposed in this paper. The proposed TLC-ORC system aims at obtaining better performance of temperature matching between working fluid and heat source, leading to better overall system performance than that of the conventional dual-loop ORC system. The proposed cascade cycle adopts TLC to replace the High-Temperature (HT) cycle of the conventional dual-loop ORC system. The comprehensive comparisons between the conventional dual-loop ORC and the proposed TLC-ORC system have been conducted using the first and second law analysis. Effects of evaporating temperature for HT and Low-Temperature (LT) cycle, as well as different HT and LT working fluids, are systematically investigated. The comparisons of exergy destruction and exergy efficiency of each component in the two systems have been studied. Results illustrate that the maximum net power output, thermal efficiency, and exergy efficiency of a conventional dual-loop ORC are 8.8 kW, 18.7%, and 50.0%, respectively, obtained by the system using cyclohexane as HT working fluid at THT,evap = 470 K and TLT,evap = 343 K. While for the TLC-ORC, the corresponding values are 11.8 kW, 25.0%, and 65.6%, obtained by the system using toluene as a HT working fluid at THT,evap = 470 K and TLT,evap = 343 K, which are 34.1%, 33.7%, and 31.2% higher than that of a conventional dual-loop ORC.

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35

Доценко, D. Dotsenko, Сторчеус, Yu Storcheus, Сторчеус i M. Storcheus. "IMPROVING ENERGY EFFICIENCY OF TRANSPORT CARS BY OPTIMIZING CHARACTERISTICS OF THERMAL COMPRESSORS". Alternative energy sources in the transport-technological complex: problems and prospects of rational use of 3, nr 1 (16.03.2016): 132–37. http://dx.doi.org/10.12737/18460.

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The features of the operating cycle and schematics thermal compressors operating on the principles of energy cascade. Factors affecting the efficiency of single- and two-stage thermal compressor circuits. The effect of operating and design parameters of the transformer cascade energy performance of one - and two-stage thermal compressor. Recommendations on further improvement of the thermal characteristics of the compressor cascade.

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Kim, Beom-Jun, Hye-Jin Cho, Soo-Jin Lee, Taek-Don Kwon i Jae-Weon Jeong. "Applicable design of multi-functional cascade heat pump system for an office building". E3S Web of Conferences 356 (2022): 01033. http://dx.doi.org/10.1051/e3sconf/202235601033.

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When the cascade heat pump system is applied as a multi-functional system that can be used not only for hot water supply but also for air-conditioning of buildings, the low-stage cycle is responsible for indoor heating and cooling thermal load, and the high-stage cycle is responsible for hot water supply by raising the refrigerant temperature. Unlike the existing cascade heat pump system designed with only one operation mode for hot water supply, the multi-functional cascade heat pump system should be considered with various parameters. This study was proposed a design sequence of the cascade heat pump system for building application, and the energy-saving performance was compared with the existing cascade heat pump system for hot water supply and parallel heat pump system for air-conditioning. The office building was set for the study, and the thermal load of the building was calculated in the TRNSYS program. The systems were calculated using the thermodynamic equation and the model built into EnergyPlus. As a result, the system can be affected by the outdoor air heat source. The energy-saving performance was 25% for the multi-functional cascade heat pump system compared to the simultaneous use of the existing system.

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37

Yoon, Jung-In, Won-Jae Choi, Sanggyu Lee, Kunhyung Choe i Gyu-Jin Shim. "Efficiency of Cascade Refrigeration Cycle Using C3H8, N2O, and N2". Heat Transfer Engineering 34, nr 11-12 (26.09.2013): 959–65. http://dx.doi.org/10.1080/01457632.2012.753575.

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38

Südhof, Thomas C. "The synaptic vesicle cycle: a cascade of protein–protein interactions". Nature 375, nr 6533 (czerwiec 1995): 645–53. http://dx.doi.org/10.1038/375645a0.

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39

He, Yijian, i Guangming Chen. "Equivalent Cycle and Optimization of Auto-Cascade Absorption Refrigeration Systems". Journal of Thermal Science 29, nr 4 (4.07.2020): 1053–62. http://dx.doi.org/10.1007/s11630-020-1333-z.

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40

Nóbrega, C. E. L., i L. A. Sphaier. "Modeling and simulation of a Desiccant–Brayton Cascade refrigeration cycle". Energy and Buildings 55 (grudzień 2012): 575–84. http://dx.doi.org/10.1016/j.enbuild.2012.09.026.

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41

UDDIN, KUTUB, TAKAHIKO MIYAZAKI, SHIGERU KOYAMA i BIDYUT BARAN SAHA. "PERFORMANCE INVESTIGATION OF ADSORPTION–COMPRESSION HYBRID REFRIGERATION SYSTEMS". International Journal of Air-Conditioning and Refrigeration 21, nr 04 (grudzień 2013): 1350024. http://dx.doi.org/10.1142/s2010132513500247.

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An analytical investigation on the performance of adsorption–compression hybrid refrigeration systems with two different cycle configurations, cascade type and subcool type has been performed. In the former type, a cascade condenser is used which works as a condenser for mechanical compression cycle and evaporator for adsorption cycle. In the latter type, an evaporative subcooler is used which subcool the fluid of mechanical compression cycle. The refrigerants examined for the mechanical compression cycle are R134a, R152a, R1234yf and R1234ze whereas ethanol is the refrigerant for the adsorption cycle. The main feature of the proposed system is the capability to significantly reduce work input for the mechanical compressor which results up to 30% energy saving potential depending on the selection of refrigerant and system configuration. Based on the thermodynamic properties and laws the study analyzed the effect of the major design parameters such as evaporation temperature, compressor discharge pressure and desorption temperature on the system performances.

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42

Rangel, Victor Bitencour, Antonio Gabriel Souza Almeida, Francisco Souza Almeida i Luiz Gustavo da Cruz Duarte. "CASCADE REFRIGERATION SYSTEM FOR LOW TEMPERATURES USING NATURAL FLUIDS". REVISTA FOCO 15, nr 1 (1.08.2022): e295. http://dx.doi.org/10.54751/revistafoco.v15n1-013.

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Cascade refrigeration systems work with two or more serial disposed cycles and can obtain internal temperatures below -60°C, which is necessary for several activities in medicine and scientific research. This paper presents a thermodynamic analysis of cascade system refrigeration using natural refrigerant fluids for ultra low temperatures. These fluids areenvironmentally friendly refrigerant and are an alternative to hydro chlorofluorocarbons (HCFCs) and to hydrofluorocarbons (HFCs). Energy and exergy analyses were performed using a thermodynamic model based on the law of conservation of massand also on the first and second laws of thermodynamics. A simulator was developed to assess the technical practicability of this system, considering it running as a real refrigeration cycle.

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43

Cho, Jung-Ho, i Yu-Mi Kim. "A Simulation Study on the Cascade Refrigeration Cycle for the Liquefaction of the Natural Gas [2]: An Application to the Multistage Cascade Refrigeration Cycle". Journal of the Korea Academia-Industrial cooperation Society 12, nr 2 (28.02.2011): 1013–19. http://dx.doi.org/10.5762/kais.2011.12.2.1013.

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44

YU. RYAGIN, MIKHAIL, i LEV B. RYASHKO. "THE ANALYSIS OF THE STOCHASTICALLY FORCED PERIODIC ATTRACTORS FOR CHUA'S CIRCUIT". International Journal of Bifurcation and Chaos 14, nr 11 (listopad 2004): 3981–87. http://dx.doi.org/10.1142/s0218127404011600.

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This report shows the results of sensitivity analysis for Chua's circuit periodic attractors under small disturbances. Sensitivity analysis is based on the quasipotential method. Quasipotential's first approximation in the neighborhood of the limit cycle is defined by the matrix of orbital quadratic form, named stochastic sensitivity function (SSF). SSF is defined for the points of the nonperturbed limit cycle and can be computed using the numerical algorithm. Stochastic sensitivity of the limit cycles for the Chua's circuit period doubling cascade is investigated. The growth of the stochastic sensitivity under transition to chaos is shown.

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45

Liu, Xiu Fang, Fa Hui Wang i Fan Mao Meng. "Experimental Study on Two-Stage Cascade Low Temperature Pre-Cooling Equipment". Applied Mechanics and Materials 42 (listopad 2010): 322–25. http://dx.doi.org/10.4028/www.scientific.net/amm.42.322.

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A two-stage cascade pre-cooling test bed was designed and set up to develop a -30°C /-60°C pre-cooling equipment. An internal heater exchanger and a condenser were set in low-temperature cycle. Theoretically the two stages can work stably at setting temperature and the low-temperature cycle can operate independently with aided starting of the high-temperature cycle. The experimental results indicate that the test bed can provide cooling capacity steadily at -46°C and -100°C respectively and the low-temperature cycle cannot operate alone for compressor overload protection. Based on the analysis, the possible reasons and detailed suggestions were put forward.

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46

Xiao, Jian, i Ying Fu Liu. "Thermodynamic Analysis of a R32/CO₂ Cascade Refrigeration Cycle". Advanced Materials Research 732-733 (sierpień 2013): 527–30. http://dx.doi.org/10.4028/www.scientific.net/amr.732-733.527.

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A R32/CO2 cascade refrigeration cycle was analyzed thermodynamically, the results show that: Under given working conditions, there exists the best condensing temperature of the low-temperature circuit to make the maximum COP of the cycle. The lower evaporating temperature is, the lower the best condensing temperature of the low-temperature circuit is. Under the same evaporating temperature, COP increases and mH/mL decreases along with condensing temperature decreasing, under the same condensing temperature, COP decreases and mH/mL increases along with condensing temperature decreasing. To reduce the temperature difference in the cascade-condenser can increase COP and decrease mH/mL.

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47

Davies, M. R. D., i P. J. Bryanston-Cross. "Holographic Measurements and Theoretical Predictions of the Unsteady Flow in a Transonic Annular Cascade". Journal of Engineering for Gas Turbines and Power 107, nr 2 (1.04.1985): 450–57. http://dx.doi.org/10.1115/1.3239748.

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A series of measurements have been made on a transonic annular cascade. The cascade which represents the tip section of a compressor fan blade has an inlet Mach number of 1.18. By the use of external vibrators it is possible to vibrate the blades independently in torsion simulating different interblade phase angles in order to gain an understanding of shock movement and blade loading. The results presented are made over interblade phase angles of 180 and 135 deg at a blade frequency parameter of 0.1, based on chord. The holographic data obtained shows detail of shock movement during the cycle using a miniature holocamera located within the hub of the cascade. Unsteady sidewall pressure measurements have also been obtained over the vibration cycle. The data obtained have been compared with finite element calculations.

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Kumar, C. Prasanna, i N. Venugopal. "Performance and Stability Analysis of Series-Cascaded, High-Gain, Interleaved Boost Converter for Photovoltaic Applications". Power Electronics and Drives 3, nr 1 (1.06.2018): 85–97. http://dx.doi.org/10.2478/pead-2018-0022.

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Abstract Interleaved boost converters (IBCs) are cascaded in parallel in most of the applications. This novel approach connects IBC in series cascade. The IBC has an optimal operating duty cycle of 0.5. Normally, photovoltaic source voltage is low because of space constraints. In order to boost the source voltage, a conventional boost converter is replaced with series-cascaded IBC in this paper. The single-stage IBC also boosts the voltage to twice the input voltage. In the proposed converter, output voltage is about four times the input voltage with the same 0.5 duty cycle. A mathematical model is developed and simulated for the proposed work in MATLAB/Simulink platform. The output of the proposed circuit is analysed through fast Fourier transform to know the harmonic content due to the switching. The system is tested for stability with signal-flow graph modelling. The proposed work is realised using hardware and tested to validate the model.

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Yurov, Yuri B., Svetlana G. Vorsanova i Ivan Y. Iourov. "The DNA Replication Stress Hypothesis of Alzheimer’s Disease". Scientific World JOURNAL 11 (2011): 2602–12. http://dx.doi.org/10.1100/2011/625690.

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A well-recognized theory of Alzheimer’s disease (AD) pathogenesis suggests ectopic cell cycle events to mediate neurodegeneration. Vulnerable neurons of the AD brain exhibit biomarkers of cell cycle progression and DNA replication suggesting a reentry into the cell cycle. Chromosome reduplication without proper cell cycle completion and mitotic division probably causes neuronal cell dysfunction and death. However, this theory seems to require some inputs in accordance with the generally recognized amyloid cascade theory as well as to explain causes and consequences of genomic instability (aneuploidy) in the AD brain. We propose that unscheduled and incomplete DNA replication (replication stress) destabilizes (epi)genomic landscape in the brain and leads to DNA replication “catastrophe” causing cell death during the S phase (replicative cell death). DNA replication stress can be a key element of the pathogenetic cascade explaining the interplay between ectopic cell cycle events and genetic instabilities in the AD brain. Abnormal cell cycle reentry and somatic genome variations can be used for updating the cell cycle theory introducing replication stress as a missing link between cell genetics and neurobiology of AD.

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Rangel, V. B., i A. G. S. Almeida. "CASCADE REFRIGERATION SYSTEM FOR LOW TEMPERATURES USING NATURAL FLUIDS". Revista de Engenharia Térmica 20, nr 2 (28.07.2021): 20. http://dx.doi.org/10.5380/reterm.v20i2.81783.

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Cascade refrigeration systems work with two or more serial disposed cycles and can obtain internal temperatures below -60°C, which is necessary for several activities in medicine and scientific research. This paper presents a thermodynamic analysis of cascade system refrigeration using natural refrigerant fluids for ultra-low temperatures. These fluids are environmentally friendly refrigerant and are an alternative to hydro chlorofluorocarbons (HCFCs) and to hydrofluorocarbons (HFCs). Energy and exergy analyses were performed using a thermodynamic model based on the law of conservation of mass and also on the first and second laws of thermodynamics. A simulator was developed to assess the technical practicability of this system, considering it running as a real refrigeration cycle. Natural fluids have best performance energetically and environmentally.

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