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Articoli di riviste sul tema "Compression flows"

Autore: Grafiati

Pubblicato: 22 febbraio 2025

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1

Ananin, S. I. "Structure of hydrogen compression plasma flows in a magnetoplasma compressor". Journal of Applied Mechanics and Technical Physics 32, n. 4 (1992): 465–71. http://dx.doi.org/10.1007/bf00851542.

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Chen, Hao, Hui-Jun Tan, Qi-Fan Zhang e Yue Zhang. "Buzz Flows in an External-Compression Inlet with Partially Isentropic Compression". AIAA Journal 55, n. 12 (dicembre 2017): 4286–95. http://dx.doi.org/10.2514/1.j056066.

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3

Ho, Yung-Han, Chih-Chun Chan, Wen-Hsiao Peng, Hsueh-Ming Hang e Marek Domanski. "ANFIC: Image Compression Using Augmented Normalizing Flows". IEEE Open Journal of Circuits and Systems 2 (2021): 613–26. http://dx.doi.org/10.1109/ojcas.2021.3123201.

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4

Rudy, David H., James L. Thomas, Ajay Kumar, Peter A. Gnoffo e Sukumar R. Chakravarthy. "Computation of laminar hypersonic compression-corner flows". AIAA Journal 29, n. 7 (luglio 1991): 1108–13. http://dx.doi.org/10.2514/3.10710.

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Astashynski, V. M., E. A. Kostyukevich, A. M. Kuzmitski, A. A. Mishchuk e P. N. Shoronov. "Interaction between oppositely directed compression plasma flows". Journal of Applied Spectroscopy 79, n. 4 (settembre 2012): 610–15. http://dx.doi.org/10.1007/s10812-012-9647-6.

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6

Tang, Chuanbo, Xihua Sheng, Zhuoyuan Li, Haotian Zhang, Li Li e Dong Liu. "Offline and Online Optical Flow Enhancement for Deep Video Compression". Proceedings of the AAAI Conference on Artificial Intelligence 38, n. 6 (24 marzo 2024): 5118–26. http://dx.doi.org/10.1609/aaai.v38i6.28317.

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Video compression relies heavily on exploiting the temporal redundancy between video frames, which is usually achieved by estimating and using the motion information. The motion information is represented as optical flows in most of the existing deep video compression networks. Indeed, these networks often adopt pre-trained optical flow estimation networks for motion estimation. The optical flows, however, may be less suitable for video compression due to the following two factors. First, the optical flow estimation networks were trained to perform inter-frame prediction as accurately as possible, but the optical flows themselves may cost too many bits to encode. Second, the optical flow estimation networks were trained on synthetic data, and may not generalize well enough to real-world videos. We address the twofold limitations by enhancing the optical flows in two stages: offline and online. In the offline stage, we fine-tune a trained optical flow estimation network with the motion information provided by a traditional (non-deep) video compression scheme, e.g. H.266/VVC, as we believe the motion information of H.266/VVC achieves a better rate-distortion trade-off. In the online stage, we further optimize the latent features of the optical flows with a gradient descent-based algorithm for the video to be compressed, so as to enhance the adaptivity of the optical flows. We conduct experiments on two state-of-the-art deep video compression schemes, DCVC and DCVC-DC. Experimental results demonstrate that the proposed offline and online enhancement together achieves on average 13.4% bitrate saving for DCVC and 4.1% bitrate saving for DCVC-DC on the tested videos, without increasing the model or computational complexity of the decoder side.

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Kang, Hyun-Su, Sung-Yeon Kim e Youn-Jea Kim. "Wet Compression Study for an Aero-Thermodynamic Performance Analysis of a Centrifugal Compressor at Design and Off-Design Points". Processes 10, n. 5 (9 maggio 2022): 936. http://dx.doi.org/10.3390/pr10050936.

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In this study, to analyze the effect of wet compression technology on the aero-thermodynamic performance of a centrifugal compressor, a numerical analysis study was conducted on the design point and off-design point. Wet compression technology sprays water droplets at the inlet of the compressor. During the compression process, water droplets evaporate, reducing the heat of compression and reducing the compression work, which improves the efficiency of the compressor. In wet compression technology, detailed research is needed for the application to compressors because the droplet behavior affects the internal flow. The main parameters for wet compression technology are the droplet size and injection rate selection, and the flow inside the compressor changed by the droplet behavior was analyzed. When the droplet size and injection rate were changed at the design point and the off-design point, it was confirmed that a small droplet size was effective in both areas, and it was confirmed that the performance improved as the flow rate increased. The internal flow changed greatly depending on the size of the droplet. As a result, the centrifugal compressor to which the wet compression technology was applied had a lower outlet temperature than dry compression at both the design point and the off-design point and had increases in the pressure ratio and efficiency. However, the surge margin decreased by about 2% in the surge region. The reason is that due to high-speed rotation, particles move in the outer diameter direction and are driven into a tip-leakage flow, and many stagnant flows occur without flowing into the main flow. Through the study results, it was possible to understand the effects of wet compression technology on the performance and efficiency increase of centrifugal compressors and the effects of particle behavior on the internal flow of the compressor at the off-design point.

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8

Neuschwander, T. B., B. R. Macias, A. R. Hargens e Q. Zhang. "Mild External Compression of the Leg Increases Skin and Muscle Microvascular Blood Flow and Muscle Oxygenation during Simulated Venous Hypertension". ISRN Vascular Medicine 2012 (10 dicembre 2012): 1–6. http://dx.doi.org/10.5402/2012/930913.

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We studied the effect of mild external leg compression on both skin and muscle microvascular flow, and muscle oxygenation in the leg of healthy subjects during simulated venous hypertension. Skin and muscle microvascular blood flows were measured using photoplethysmography (PPG), and muscle oxygenation was measured using near-infrared spectroscopy (NIRS). Both PPG and NIRS probes were placed over the anterior compartment of the right leg in 8 healthy subjects. Measurements were taken under three experimental conditions: external leg compression (40 mmHg); simulated venous hypertension (65 mmHg thigh cuff); external leg compression during simulated venous hypertension. Muscle oxygenation was measured only under external leg compression during simulated venous hypertension. Simulated venous hypertension decreased skin and muscle microvascular blood flows from 100% (baseline) to 35.8±2.9% and 31.9±1.3% (P<0.001), respectively. External leg compression during simulated venous hypertension caused 2-fold increases in both skin and muscle microvascular blood flows compared to simulated venous hypertension (P<0.001). Similarly, external leg compression during simulated venous hypertension significantly restored muscle oxygenation by 23±7% compared to its baseline (P<0.05). Our results demonstrate that mild external leg compression counteracts the decreases in skin microvascular flow, muscle microvascular flow, and muscle oxygenation induced by simulated venous hypertension in the leg.

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Lea, C. J., e A. P. Watkins. "Differential stress modelling of turbulent flows in model reciprocating engines". Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 211, n. 1 (1 gennaio 1997): 59–77. http://dx.doi.org/10.1243/0954407971526227.

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A study is made here of the application of a differential stress model (DSM) of turbulence to flows in two model reciprocating engines. For the first time this study includes compressive effects. An assessment between DSM and k-ɛ results is made comparing with laser Doppler anemometry experimental data of the mean flow and turbulence intensity levels during intake and compression strokes. A well-established two-dimensional finite-volume computer code is employed. Two discretization schemes are used, namely the HYBRID scheme and the QUICK scheme. The latter is found to be essential if differentiation is to be made between the turbulence models. During the intake stroke the DSM results are, in general, similar to the k-ɛ results in comparison to the experimental data, except for the turbulence levels, which the DSM seriously underpredicts. This is in contrast to a parallel set of calculations of steady in-flow, which showed significant gains from using the DSM, particularly at the turbulence field level. The increased number of grid lines employed in those calculations contribute to this apparent difference between steady and unsteady flows, but cycle- to-cycle variations are more likely to be the primary cause, resulting in too high levels of turbulence intensity being measured. However, during the compression stroke the DSM returns vastly superior results to the k-ɛ model at both the mean flow and turbulence intensity levels. This is because the DSM generates an anisotropic shear stress field during the early stages of compression that suppresses the main vortical structure, in line with the experimental data.

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Genbach, A. A., e D. Y. Bondartsev. "An Analysis of Heat Exchange Crisis in the Capillary Porous System for Cooling Parts of Heat and Power Units". Proceedings of Higher Educational Institutions. Маchine Building, n. 12 (717) (dicembre 2019): 21–35. http://dx.doi.org/10.18698/0536-1044-2019-12-21-35.

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A model of dynamics of the vapor bubbles that emerge on solid surfaces of porous structures and the steam generating wall (bottom layer) is presented in this work. The model was filmed and photographed by a high-speed camera SKS-1М. The discharge of high heat flows (up to 2·106 W/m2) was maintained by the joint action of capillary and mass forces with the help of intensifiers. An analytical model was developed based on the theory of thermoelasticity. The limit state of the porous coating with poor thermal conductivity and the metal bottom layer was determined. Heat flows were calculated from the spontaneous birth of the vapour nucleus (10–8) to the material destruction (102–103 s), thus the interval from the process of relaxation to the maximum process (destruction) was described. The size of the pullout particles determined in the model at the moment of porous coating destruction showed good congruence with the experimental data obtained at the optic stand. The destruction of coating under the compression forces occurs much earlier than the tension forces. It is probable that the destruction will happen under the impact of the compression and shear forces. The intervals of the heat flow when such destruction takes place are different for quartz and granite coating. Each thickness of the pullout particles under the impact of compression forces has its limit values of the heat flows, which are located within the mentioned intervals. As the specific heat flow in the heated layer increases and, therefore, the heating time decreases, the impact of the compression stresses increases as well. Despite the high resistance to compression, destruction from the compressive heat tension occurs in more favorable conditions immediately, and in diminutive volumes. Experimental testing units, test conditions, the outcome of the heat exchange crisis, the limit state of the surface and the calculation of critical heat flows are presented. The capillary porous system that works under the joint action of capillary and mass forces is studied. The system has advantages compared to pool boiling, thin-film evaporators and heat pipes.

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11

Park, S. O., Y. M. Chung e H. J. Sung. "Numerical study of unsteady supersonic compression ramp flows". AIAA Journal 32, n. 1 (gennaio 1994): 216–18. http://dx.doi.org/10.2514/3.11973.

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12

Aleman, J. V. "Bulk and surface compression flows of polymer melts". European Polymer Journal 27, n. 3 (gennaio 1991): 221–26. http://dx.doi.org/10.1016/0014-3057(91)90096-7.

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13

Gong, Chengyue, Xiaocong Du, Bhargav Bhushanam, Lemeng Wu, Xingchao Liu, Dhruv Choudhary, Arun Kejariwal e Qiang Liu. "Layer Compression of Deep Networks with Straight Flows". Proceedings of the AAAI Conference on Artificial Intelligence 38, n. 11 (24 marzo 2024): 12181–89. http://dx.doi.org/10.1609/aaai.v38i11.29107.

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Very deep neural networks lead to significantly better performance on various real tasks. However, it usually causes slow inference and is hard to be deployed on real-world devices. How to reduce the number of layers to save memory and to accelerate the inference is an eye-catching topic. In this work, we introduce an intermediate objective, a continuous-time network, before distilling deep networks into shallow networks. First, we distill a given deep network into a continuous-time neural flow model, which can be discretized with an ODE solver and the inference requires passing through the network multiple times. By forcing the flow transport trajectory to be straight lines, we find that it is easier to compress the infinite step model into a one-step neural flow model, which only requires passing through the flow model once. Secondly, we refine the one-step flow model together with the final head layer with knowledge distillation and finally, we can replace the given deep network with this one-step flow network. Empirically, we demonstrate that our method outperforms direct distillation and other baselines on different model architectures (e.g. ResNet, ViT) on image classification and semantic segmentation tasks. We also manifest that our distilled model naturally serves as an early-exit dynamic inference model.

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Duggal, C., M. H. Weil, R. J. Gazmuri, W. Tang, S. Sun, F. O'Connell e M. Ali. "Regional blood flow during closed-chest cardiac resuscitation in rats". Journal of Applied Physiology 74, n. 1 (1 gennaio 1993): 147–52. http://dx.doi.org/10.1152/jappl.1993.74.1.147.

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Quantitative measurement of regional blood flow during cardiac arrest and resuscitation has been confined to large animals. We report on a rodent model utilizing radioactive microspheres during cardiac arrest and resuscitation for investigation of regional blood flow. Ventricular fibrillation was electrically induced in 10 pentobarbital-anesthetized Sprague-Dawley rats. Resuscitation was attempted by precordial compression followed by external direct current countershock. During precordial compression, cardiac output corresponded to 12% of prearrest flow. Similarly low flows were observed in the myocardium and brain. However, much lower flows were observed in the adrenal glands, kidneys, intra-abdominal viscera, skin, and skeletal muscle. Five of ten animals were successfully resuscitated. During precordial compression, resuscitated animals had significantly higher cardiac output (13.1 +/- 4.1 vs. 8.6 +/- 1.46 ml/min), myocardial blood flow (0.70 +/- 0.24 vs. 0.22 +/- 0.15 ml.min-1.g-1), cerebral blood flow (0.17 +/- 0.04 vs. 0.06 +/- 0.02 ml.min-1.g-1), and adrenal blood flow (1.09 +/- 0.60 vs. 0.27 +/- 0.16 ml.min-1.g-1). Thirty minutes after successful resuscitation, cardiac output and myocardial, cerebral, renal, and adrenal blood flows and blood flow to splanchnic viscera (with the exception of the spleen) had returned to > or = 70% of prearrest flows. These studies confirm the conclusion of earlier investigations in larger animals that visceral blood flow during cardiac arrest and precordial compression is preferentially distributed to the brain and myocardium. Successful cardiac resuscitation is contingent on threshold levels of myocardial blood flow that exceed 0.4 ml.min-1.g-1.

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Lin, Feng, Meilin Li e Jingyi Chen. "Long-to-Short Length-Scale Transition: A Stall Inception Phenomenon in an Axial Compressor With Inlet Distortion". Journal of Turbomachinery 128, n. 1 (1 febbraio 2005): 130–40. http://dx.doi.org/10.1115/1.2098808.

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A theoretical and experimental study of stall inception processes in a three-stage low-speed axial flow compressor with inlet distortion is presented in this paper. Since inlet distortion provides asymmetric flows imposing onto the compressor, the main goal of this research is to unveil the mechanism of how such flows initiate long and/or short length-scale disturbances and how the compression system reacts to those disturbances. It is found that the initial disturbances are always triggered by the distorted flows, yet the growth of such disturbances depends on system dynamics. While in many cases the stall precursors were the short length-scale spikes, there were some cases where the compressor instability was triggered after the disturbances going through a long-to-short length-scale transition. A Moore-Greitzer-based (system scale) model was proposed to qualitatively explain this phenomenon. It was found that, when the compressor operated in a region where the nonlinearity of the characteristics dominated, long length-scale disturbances induced by the inlet distortion would evolve into short length-scale disturbances before they disappeared or triggered stall. However, the model was not able to predict the fact that many disturbances that were triggered by the distorted sector(s) were completely damped out in the undistorted sector(s). It is thus suggested that in future research of compressor instability, one should consider the flows in blade passage scale, the dynamics in system scale, and their interaction simultaneously.

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Lee, Sungyeop, e Junghyo Jo. "Information Flows of Diverse Autoencoders". Entropy 23, n. 7 (5 luglio 2021): 862. http://dx.doi.org/10.3390/e23070862.

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Deep learning methods have had outstanding performances in various fields. A fundamental query is why they are so effective. Information theory provides a potential answer by interpreting the learning process as the information transmission and compression of data. The information flows can be visualized on the information plane of the mutual information among the input, hidden, and output layers. In this study, we examine how the information flows are shaped by the network parameters, such as depth, sparsity, weight constraints, and hidden representations. Here, we adopt autoencoders as models of deep learning, because (i) they have clear guidelines for their information flows, and (ii) they have various species, such as vanilla, sparse, tied, variational, and label autoencoders. We measured their information flows using Rényi’s matrix-based α-order entropy functional. As learning progresses, they show a typical fitting phase where the amounts of input-to-hidden and hidden-to-output mutual information both increase. In the last stage of learning, however, some autoencoders show a simplifying phase, previously called the “compression phase”, where input-to-hidden mutual information diminishes. In particular, the sparsity regularization of hidden activities amplifies the simplifying phase. However, tied, variational, and label autoencoders do not have a simplifying phase. Nevertheless, all autoencoders have similar reconstruction errors for training and test data. Thus, the simplifying phase does not seem to be necessary for the generalization of learning.

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ITOH, Hajime. "Visualization of Velocity Fields around Hypersonic Compression Corner Flows". Journal of the Visualization Society of Japan 24, Supplement2 (2004): 83–84. http://dx.doi.org/10.3154/jvs.24.supplement2_83.

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Shymanski, V. I., V. V. Shevelyova, V. M. Astashynski e A. M. Kuzmitski. "Oxidation of Zirconium Alloy Processed with Compression Plasma Flows". Journal of Surface Investigation: X-ray, Synchrotron and Neutron Techniques 15, S1 (dicembre 2021): S193—S200. http://dx.doi.org/10.1134/s1027451022020379.

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Sajben, Miklos. "Propagation of weak compression waves in nonuniform channel flows". Journal of Propulsion and Power 5, n. 2 (marzo 1989): 154–57. http://dx.doi.org/10.2514/3.23130.

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Qu, Miao, Fanhang Kong, Sha Yan, V. V. Uglov, Jianming Xue e Yugang Wang. "Damages on pure tungsten irradiated by compression plasma flows". Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms 444 (aprile 2019): 33–37. http://dx.doi.org/10.1016/j.nimb.2018.12.050.

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Uglov, V. V., N. T. Kvasov, R. S. Kudaktsin, Yu A. Petukhou, V. M. Astashinskii e A. M. Kuzmitski. "Photovoltaic Effect in Silicon Treated by Compression Plasma Flows". Energy Procedia 44 (2014): 10–15. http://dx.doi.org/10.1016/j.egypro.2013.12.003.

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22

Baibekova, F. N., V. V. Podoltsev, N. M. Bespalova e L. A. Sologubova. "Overview of the ways to reduce telemetric information redundancy". Radio industry (Russia) 29, n. 2 (30 maggio 2019): 8–16. http://dx.doi.org/10.21778/2413-9599-2019-29-2-8-16.

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The redundancy of telemetric information significantly complicates the real-time processing of the information flows. To speed up the telemetry processing process, the methods for telemetric information redundancy reduction should be applied in order to reduce its flows entering the monitoring systems while maintaining a high speed of processing and reliability of the information. The article provides an overview of the methods for reduction of telemetric information redundancy, such as the increase in PHY-rate of telemetry channel, the Huffman algorithm, the batch mechanism for generation and transmission of telemetry information, the adaptive difference algorithm, the algorithm for transmission of the information based on its representation by residual images, Golomb-Rice codes, reversible compression method. The advantages and disadvantages of each of them are considered. Recommendations on the use of multi-level telemetry information compression system are given, which makes it possible to effectively combine target data compression algorithms that give the highest compression ratio depending on the type of telemetry information transmitted.

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Aji Suryadi, Yanuar e Gunawan. "Compressor Piping Design Effect on Vibration Data". Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 88, n. 1 (11 ottobre 2021): 94–108. http://dx.doi.org/10.37934/arfmts.88.1.94108.

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One of the systems for oil and gas production supports is the nitrogen compression system. Problem found that condition of the compressor has high vibration with the maximum overall the first compressor is 9,813 mm / s RMS, the second compressor is 7,439 mm / s RMS, the third compressor is 7,430 mm / s RMS, the fourth compressor is 13.47 mm / s RMS, the fifth compressor is 13,220 mm / s RMS, and sixth compressor already damaged. This research will discuss the nitrogen compression process in terms of the characteristics of the output fluid flow from the compressor using computational fluid dynamics. The first piping system shows that the standby compressor's flow has a higher pressure reaching 10.72 - 11.82 Pa but it is still acceptable. The second piping system with two compressors in operation shows that the pipeline flows in the opposite direction with high pressure. Flow turbulence occurs, resulting in a higher speed. The highest pressure in the pipeline reaches 44.79 Pa, mostly at the fifth and sixth compressors. The conclusion from this research there is high pressure backflow when one compressor stops and another compressor start running. Prevents direct pressure to the compressor or the condensed fluid from the gas flowing and entering the compressor used valve addition.

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Wilcox, David C. "Supersonic compression-corner applications of a multiscale model forturbulent flows". AIAA Journal 28, n. 7 (luglio 1990): 1194–98. http://dx.doi.org/10.2514/3.25191.

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Hu, Yan-Chao, Wen-Feng Zhou, Gang Wang, Yan-Guang Yang e Zhi-Gong Tang. "Bistable states and separation hysteresis in curved compression ramp flows". Physics of Fluids 32, n. 11 (1 novembre 2020): 113601. http://dx.doi.org/10.1063/5.0029150.

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Cherenda, N. N., A. P. Laskovnev, A. V. Basalai, V. V. Uglov, V. M. Astashynski e A. M. Kuzmitski. "Erosion of materials under the effect of compression plasma flows". Inorganic Materials: Applied Research 6, n. 2 (marzo 2015): 114–20. http://dx.doi.org/10.1134/s2075113315020070.

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Cherenda, N. N., A. A. Smilgin, V. V. Uglov, V. M. Astashynski, A. M. Kuzmitski e G. E. Remnev. "Cleaning of steel surface from scale by compression plasma flows". Surface and Coatings Technology 255 (settembre 2014): 79–83. http://dx.doi.org/10.1016/j.surfcoat.2014.01.002.

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PASHA, Amjad A., e Khalid A. JUHANY. "Numerical simulation of compression corner flows at Mach number 9". Chinese Journal of Aeronautics 33, n. 6 (giugno 2020): 1611–24. http://dx.doi.org/10.1016/j.cja.2020.01.005.

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Leyvi, A. Ya, e A. P. Yalovets. "Mechanisms of surface formation at treatment with compression plasma flows". Journal of Physics: Conference Series 1115 (novembre 2018): 032018. http://dx.doi.org/10.1088/1742-6596/1115/3/032018.

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Zhang, Shuo, Dongdong Zhong, Hao Wang, Xingshuang Wu e Ning Ge. "Application of a Novel High-Order WENO Scheme in LES Simulations". Applied Sciences 14, n. 17 (4 settembre 2024): 7875. http://dx.doi.org/10.3390/app14177875.

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To achieve high-fidelity large eddy simulation (LES) predictions of complex flows while keeping computational costs manageable, this study integrates a high-order WENO-ZQ scheme into the LES framework. The WENO-ZQ scheme has been extensively studied for its accuracy, robustness, and computational cost in inviscid flow applications. This study extended the WENO-ZQ scheme to viscous flows by integrating it into a three-dimensional structured grid LES CFD solver. High-fidelity simulations of turbulent boundary layer flow and supersonic compression ramp flows were conducted, with the scheme being applied for the first time to study laminar boundary layer transition and separation flows in the high-load, low-pressure turbine PakB cascade. Classic numerical case validations for viscous conditions demonstrate that the WENO-ZQ scheme, compared to the same-order WENO-JS scheme, exhibits lower dispersion and dissipation errors, faster convergence, and better high-frequency wave resolution. It maintains high-resolution accuracy with fewer grid points. In application cases, the WENO-ZQ scheme accurately captures the three-dimensional flow characteristics of shockwave–boundary layer interactions in supersonic compression ramps and shows high accuracy and resolution in predicting separation and separation-induced transition in low-pressure turbines.

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Ryshchenko, I. M., S. М. Bykanov, K. O. Gorbunov, A. M. Myronov e M. V. Ilchenko. "COMPLEX THERMAL INTEGRATION OF THE RECTIFICATION PROCESS OF THE BENZENE-TOLUENE MIXTURE". Integrated Technologies and Energy Saving, n. 2 (5 luglio 2024): 14–22. http://dx.doi.org/10.20998/2078-5364.2024.2.02.

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Comprehensive thermal integration of the benzene-toluene mixture rectification process was carried out. Thermal integration was carried out using pinch analysis methods with using thermocompression. The principle technological scheme of rectification of the benzene-toluene mixture with a productivity of 11 t/h is taken as a basis. For this performance, the consumption of flows, their temperatures, heat load, and flow heat capacities are calculated on the basis of the material and heat balance. Based on the calculated data, a flow table was created. Three hot streams are selected for integration: the distillate, the tailings, and the vapor from the top of the column, and two cold streams: the initial mixture and the column cube. The necessary degree of vapor compression is calculated for thermocompression. For a given degree of compression, the temperature of the steam after compression and the temperature of its condensation were calculated. Based on the technical and economic considerations, the minimum temperature difference DTmin=12 °С was determined for this technological scheme of the rectification process. For the selected DTmin, the component curves of the flows are constructed. Using the table algorithm method, the temperatures of the furnace for hot and cold flows were determined, which are ТНpinh=82 °С, ТСpinh=70 °С. The minimum number of hot and cold utilities is determined: QНmin and QCmin. For the selected DTmin, heat recovery was obtained in the amount of Qrek=2186,82 kW. A grid diagram is constructed, heat exchangers are located in accordance with CP and N rules. A technological scheme of the rectification process after reconstruction using thermocompression is proposed. The upgraded scheme includes the use of four recuperative heat exchangers, one heater and two coolers to achieve target flow temperatures. It is recommended to install a compressor for thermocompression. The use of Alfa Laval plate heat exchangers is proposed as heat exchange equipment. The payback period of the proposed solution is approximately two to two and a half years.

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Chen, Guo-Qing, Hongyuan Li, Pengyu Lv e Huiling Duan. "An improved multiphase lattice Boltzmann flux solver with phase interface compression for incompressible multiphase flows". Physics of Fluids 35, n. 1 (gennaio 2023): 013310. http://dx.doi.org/10.1063/5.0131506.

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Numerical dissipation is ubiquitous in multiphase flow simulation. This paper introduces a phase interface compression term into the recently developed multiphase lattice Boltzmann flux solver and achieves an excellent interface maintenance. Here, the phase interface compression term only works in the interface region and is solved as the flux in finite volume discretization. At each cell interface, the interfacial compression velocity [Formula: see text] is determined by local reconstruction velocities of the multiphase lattice Boltzmann flux solver, which maintains the consistency of the flux evaluation. Meanwhile, the interfacial order parameter C in the phase interface compression term is obtained by the second order upwind scheme according to the interface normal direction. Numerical validation of the present model has been made by simulating the Zalesak problem, the single vortex problem, Rayleigh–Taylor instability, and bubble rising and coalescence. The obtained results indicate the validity and reliability of the present model.

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33

Hammer, J., e C. J. Newth. "Effect of lung volume on forced expiratory flows during rapid thoracoabdominal compression in infants". Journal of Applied Physiology 78, n. 5 (1 maggio 1995): 1993–97. http://dx.doi.org/10.1152/jappl.1995.78.5.1993.

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Abstract (sommario):

The rapid thoracoabdominal compression (RTC) technique is commonly used in pulmonary function laboratories to assess flow-volume relationships in infants unable to produce a voluntary forced expiration maneuver. This technique produces forced expiratory flows over only a small lung volume segment (i.e., tidal volume). It has been argued that the RTC technique should be modified to measure flow-volume relationships over a larger portion of the vital capacity range to imitate the voluntary maximal forced expiratory maneuver obtained in older children and adults. We examined the effect of volume history on forced expiratory flows by generating forced expiratory flow-volume curves by RTC from well-defined inspiratory volumes delineated by inspiratory pressures of 10, 20, 30, and 40 cmH2O down to residual volume (i.e., the reference volume) in seven intubated and anesthetized infants with normal lungs [age 8.0 +/- 2.0 (SE) mo, weight 6.7 +/- 0.6 kg]. We compared maximal expiratory flows at isovolume points (25 and 10% of forced vital capacity) and found no significant differences in maximal isovolume flow rates measured from the different lung volumes. We conclude that there is no obvious need to initiate RTC from higher lung volumes if the technique is used for flow comparisons. However, compared with measurements of maximal flows at functional residual capacity by RTC from end-tidal inspiration, the initiation of RTC from a defined and reproducible inspiratory level appears to decrease the intrasubject variability of the maximal expiratory flows at low lung volumes.

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34

Dang, T. Q. "A Fully Three-Dimensional Inverse Method for Turbomachinery Blading in Transonic Flows". Journal of Turbomachinery 115, n. 2 (1 aprile 1993): 354–61. http://dx.doi.org/10.1115/1.2929241.

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This paper presents a procedure to extend a recently developed fully three-dimensional inverse method for highly loaded turbomachine blades into the transonic-flow regime. In this inverse method, the required three-dimensional blade profile to produce a prescribed swirl schedule is determined iteratively using the blade boundary conditions. In the present implementation, the flow is assumed to be inviscid and the blades are assumed to be infinitely thin. The relevant equations are solved in the conservative forms and are discretized in all three directions using a finite-volume technique. Calculations are carried out for the design of high-pressure axial- and centrifugal-compressor rotors. These examples include prescribed swirl schedules corresponding to blade designs that are shock-free and blade designs that have rapid compression regions in the blade passage.

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35

Busarov, S. S., R. E. Kobylskiy e N. G. Sinitsin. "Theoretical Assessment of Possible Reduction in Mass Leaks of Working Medium from a Reciprocating Compressor Chamber". Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, n. 2 (141) (giugno 2022): 101–11. http://dx.doi.org/10.18698/0236-3941-2022-2-101-111.

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The paper considers mass leaks of compressible medium through piston seals from the working chamber of a reciprocating compressor and possible ways of reducing those. We propose a monolithic lip piston design that should reduce mass leaks of the working medium and increase the efficiency of the piston compressor unit. We developed a computational technique that takes into account the processes inside the actual second compressor stage, including gas flows through imperfect seals in the working chamber. Combining previously published analytical equations with our promising piston seal design led to improving the following integral characteristics of the compressor stage: energy conversion efficiency, volumetric efficiency, gas compression temperature. Using the monolithic lip piston proposed should increase the reciprocating compressor unit efficiency by approximately 18 % via reducing the equivalent gap and increase volumetric efficiency by approximately 20 %, as mass leaks decrease while the mass of gas in the working chamber increases; as a result, the gas compression temperature should increase by approximately 18 %. We consider the monolithic lip piston proposed to be a promising piston seal design capable of reducing existing mass leaks, improving the indicated efficiency of the long-stroke second compressor stage along with the volumetric efficiency, and increasing the performance

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36

Shimanski, V. I., A. Evdokimovs, V. V. Uglov, N. N. Cherenda, V. M. Astashinski, A. M. Kuzmitsky, N. V. Bibik e E. A. Petrikova. "Modification of the structure of the hypereutectic silumin alloy Al-44Si under the action of compression plasma flows". Physics and Chemistry of Materials Treatment 1 (2021): 40–50. http://dx.doi.org/10.30791/0015-3214-2021-1-40-50.

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Abstract (sommario):

Effects of the high-energy compression plasma flows on the structure, elemental composition, and phase state of Al-44 at.% Si hypereutectic silumin alloy have been investigated. Using scanning electron and optical microscopy it was found decreasing in grain size of both primary silicon particles and Al-Si eutectic parts with increase of absorbed energy density of compression plasma flows. The primary silicon crystals were dispersed down to 300 nm in the result of high cooling rate of the melted layer after its homogenization by means of hydrodynamic mixing. It was found that increase in the absorbed energy density, homogenization of elemental composition in the modifies layer occurs due to increase in lifetime of the melted state and more efficiency mixing process.

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37

Kochanenko, Viktor, e Maria Aleksandrova. "COUPLING OF TWO UNIFORM FLOWS". Construction and Architecture 8, n. 4 (15 ottobre 2020): 83–86. http://dx.doi.org/10.29039/2308-0191-2020-8-4-83-86.

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Abstract (sommario):

The authors consider the problem of coupling two two-dimensional in terms of turbulent potential uniform flows. The flow movement is considered in a smooth horizontal channel with relatively short length of watercourses, when the flow resistance forces can be ignored. The main task is to determine the most rational form of the side walls of the flow interface. Radial spreading of a turbulent flow can be one of the main types of General flows for coupling various forms of flow. First, the flow is transferred through a simple expansion wave to a radial one, then through a simple compression wave it is transferred to a uniform flow. The solution of the problem with this formulation allowed us to improve and update the solution of problems on the coupling of flows.

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38

Cunningham, R. G. "Liquid Jet Pumps for Two-Phase Flows". Journal of Fluids Engineering 117, n. 2 (1 giugno 1995): 309–16. http://dx.doi.org/10.1115/1.2817147.

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Abstract (sommario):

Isothermal compression of a bubbly secondary fluid in a mixing-throat and diffuser is described by a one-dimensional flow model of a liquid-jet pump. Friction-loss coefficients used in the four equations may be determined experimentally, or taken from the literature. The model reduces to the liquid-jet gas compressor case if the secondary liquid is zero. Conversely, a zero secondary-gas flow reduces the liquid-jet gas and liquid (LJGL) model to that of the familiar liquid-jet liquid pump. A “jet loss” occurs in liquid-jet pumps if the nozzle tip is withdrawn from the entrance plane of the throat, and jet loss is included in the efficiency equations. Comparisons are made with published test data for liquid-jet liquid pumps and for liquid-jet gas compressors. The LJGL model is used to explore jet pump responses to two-phase secondary flows, nozzle-to-throat area ratio, and primary-jet velocity. The results are shown in terms of performance curves versus flow ratios. Predicted peak efficiencies are approximately 50 percent. Under severe operating conditions, LJGL pump performance curves exhibit maximum-flow ratios or cut-offs. Cut-off occurs when two-phase secondary-flow streams attain sonic values at the entry of the mixing throat. A dimensionless number correlates flow-ratio cut-offs with pump geometry and operating conditions. Throat-entry choking of the secondary flow can be predicted, hence avoided, in designing jet pumps to handle two-phase fluids.

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39

Genbach, A. A., e D. Yu Bondartsev. "Science-Based Procedure for Designing Tubular Porous Cooling Systems for Thermal Power Plant Equipment Components". Herald of the Bauman Moscow State Technical University. Series Mechanical Engineering, n. 3 (126) (giugno 2019): 89–106. http://dx.doi.org/10.18698/0236-3941-2019-3-89-106.

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Abstract (sommario):

We investigated critical heat flux phenomena in metallic and porous structures characterised by low thermal conductivity. These structures are used to cool various thermal power plant equipment; their operation involves both gravity and capillary forces. The paper describes the failure mechanism in metallic steam generator surfaces and poorly thermally conductive low-porosity coatings made of natural mineral media (such as granite). We determined how heat flows depend on their duration and penetration depth of thermal disturbance. Tubular porous systems are less bulky and feature high intensity, higher thermal conductivity and reliability. We show that for granite coatings the maximum thickness of the particles detached due to compression forces is (0.25...0.3)·10--2 m. The compression curve sections that govern detachment of particles larger than 0.3·10--2 m are shadowed by the melt curve for high heat flows and short exposure times and by the tension curve in the case of low heat flows and short periods of time. The investigation should help us to design porous coatings usable in cooling systems.

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40

Shymanski, V. I., V. V. Sheveleva, V. V. Uglov, V. M. Astashynski e A. M. Kuzmitski. "Oxidation of zirconium alloyed with chromium atoms by means of compression plasma flows impact". Physics and Chemistry of Materials Treatment 3 (2023): 18–32. http://dx.doi.org/10.30791/0015-3214-2023-3-18-32.

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Abstract (sommario):

The results of investigation of the zirconium structure on the first stage of oxidation at temperature 700 °C in the air atmosphere after 15 minutes are presented. The commercial pure zirconium alloy as well as zirconium alloyed with chromium atoms by means of compression plasma flows impact are investigated. The results showed the possibility to form the top layer in zirconium alloyed with chromium when a thin chromium coating (1 mm) was deposited on the surface and the compression plasma flow with the absorbed energy density 25 – 43 J/cm2 influenced. Due to alloying with chromium, the high-temperature β-phase of zirconium is stabilized at room temperature as β-Zr(Cr) solid solution and martensite α′-Zr phase is formed. The oxidation at temperature 700 °C demonstrated the higher oxidation resistance of the zirconium samples treated with compression plasma flows at the highest absorbed energy density 43 J/cm2. This regime modified the top layer of the zirconium sample without β-Zr(Cr) solid solution formation which enhances the oxygen diffusion.

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41

Le Souef, P. N., D. M. Hughes e L. I. Landau. "Effect of compression pressure on forced expiratory flow in infants". Journal of Applied Physiology 61, n. 5 (1 novembre 1986): 1639–46. http://dx.doi.org/10.1152/jappl.1986.61.5.1639.

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Abstract (sommario):

The effect of the force of compression on expiratory flow was evaluated in 19 infants (2-13 mo of age) with respiratory illnesses of varying severity. An inflatable cuff was used to compress the chest and abdomen. Expiratory flow and volume, airway occlusion pressure, cuff pressure (Pc), and functional residual capacity were measured. Transmission of pressure from cuff to pleural space was assessed by a noninvasive occlusion technique. Close correlations (P less than 0.001) were found between Pc and the change in pleural pressure with cuff inflation (delta Ppl,c). Pressure transmission was found to vary between two cuffs of different design and between infants. Several forced expirations were then performed on each infant at various levels of delta Ppl,c. Infants with low maximal expiratory flows at low lung volumes required relatively gentle compression to achieve flow limitation and showed decreased flow for firmer compressions. Flow-volume curves in each infant tended to become more concave as delta Ppl,c increased. These findings underline the importance of knowledge of delta Ppl,c in interpreting expiratory flow-volume curves in infants.

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42

Chen, Jiann Lin, Chieh Ju Tsai e Hsiang-Chen Hsu. "Simulations of unsteady flows with adsorption equilibrium in dynamic axial compression column". Advances in Mechanical Engineering 12, n. 6 (giugno 2020): 168781402093709. http://dx.doi.org/10.1177/1687814020937092.

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Abstract (sommario):

Simulated moving bed chromatography process, which is a multicolumn chromatography process, has been used in various industrial applications. Dynamic axial compression columns are key elements in simulated moving beds, and their flow characteristics are worth exploring using state-of-the-art numerical methodologies. In this study, new fluid distributors for the dynamic axial compression column were designed and fabricated based on mass conservation in fluid mechanics and the computer-aided design in the preliminary stage. Computational fluid dynamics was employed to resolve the flow field, and the numerical chromatograms were validated by laboratory experiments. For the computational fluid dynamics–based simulation of flow in the dynamic axial compression, the transient laminar flow fields were described by the momentum and species transport equations with Darcy’s law to model the porous zone in the packed bed. In addition, reverse engineering processes were applied to obtain the unknown physical parameters, such as viscous resistance and adsorption equilibrium coefficients. Moreover, including the adsorption equilibrium equation in the fundamental governing equations made the simulated results agree with the experimental data in chromatograms, providing a more feasible result for practical applications.

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43

Tynnikov, Yu G. "To the Use of Low Temperature Working Fluids and Supercritical Fluids to Reduce the Carbonic Traces in the Production of Urea and in the Pyrolysis of Hydrocarbons". Oil and Gas Technologies 139, n. 2 (2022): 24–32. http://dx.doi.org/10.32935/1815-2600-2022-139-2-24-32.

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Abstract (sommario):

Low-temperature working fluids and supercritical fluids for use in compressor equipment drives in a number of areas are considered: production of urea, pyrolysis of hydrocarbons in the production of olefins. In the existing technologies, the energy consumption in the form of high-pressure steam for compression is very high. The use of closed gas turbine cycles will significantly reduce the consumption of such high-temperature energy while simultaneouslyusing the heat of intermediate technological flows, saturated low-pressure steam and additional low-potential heat discharged under existing conditions to cooling towers or leaving with flue gases.

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44

Valiakhmetov, R. I., E. R. Bashirova, A. I. Galyautdinov, R. D. Rakhmangulov, I. V. Kostitsyna, A. O. Khudyakov e I. M. Khusnullin. "ROOT ANALYSIS OF LOSS STRUCTURAL INTEGRITY FOR OIL COOLING RADIATORS IN COMPRESSOR STATIONS PUMPING ASSOCIATED PETROLEUM GAS CONTAINING WET H2S". Problems of Gathering Treatment and Transportation of Oil and Oil Products, n. 5 (8 novembre 2024): 54–66. http://dx.doi.org/10.17122/ntj-oil-2024-5-54-66.

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Abstract (sommario):

One of the main problems in the associated petroleum gas treatment is its further beneficial usage. Gases of the end stages of separation require special technical solutions when involving them in the production process due to low pressure. At the same time, gases of the first stages of separation by 70–90 % of the total amount are mainly used in gas processing plants. Gas of the end stages of separation contains components C3+ and higher from 400 to 2000 g/m3 and is a valuable petrochemical raw material. To transporting gas of the end stages of separation, compression is necessary to achieve sufficient pressure. When compressing gases of the end stages of separation, a significant amount of unstable condensate containing hydrocarbons C4–C12 and water is released. In addition, the end-stage gas is saturated with sulfur compounds (H2S and R-SH), which evaporate intensively from the crude oil after its heating from the end-stage separators of oil treatment. The equipment of compressor stations for gas treatment and transportation, as a rule, does not have protection against internal corrosion. Recently, failures of cooling system radiators, pipes of air gas cooling devices made of non-ferrous metal alloys have been recorded. Radiator failures are associated with the loss of their structural integrity. Oil stains without visible flows, cracks or pits appear on the outer surface of the radiator cooling channels, while in the channels of copper alloy channels radiators, clogging of individual channels is often observed over a short period of operation of the compressor station. Understanding the causes of leaks in liquid cooling radiators as part of compressor stations for pumping associated petroleum gas of the end stages of separation is an important aspect for ensuring reliable operation of process equipment and preventing possible emergency situations. The article reflects the results of studies aimed at identifying the causes of radiators structural integrity loss of oil cooling systems in the composition of block compressor stations for compression of associated petroleum gas containing hydrogen sulfide and moisture. Solutions and recommendation to minimize the risks of equipment failures of for compression stations are made.

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45

Ananin, Siarhei I., Valiantsin M. Astashynski e S. P. Zhvavy. "DYNAMICS OF THERMAL ACTION OF COMPRESSION PLASMA FLOWS ON GERMANIUM SURFACE". High Temperature Material Processes (An International Quarterly of High-Technology Plasma Processes) 17, n. 4 (2013): 257–64. http://dx.doi.org/10.1615/hightempmatproc.v17.i4.70.

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46

Kumar, Naresh, e Manoj T. Nair. "Suitability of Density-Corrected Spalart–Allmaras Model for Compression Corner Flows". Journal of Thermophysics and Heat Transfer 29, n. 2 (aprile 2015): 423–28. http://dx.doi.org/10.2514/1.t3864.

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47

Tang, Ming-Zhi, Gang Wang, Zhu-Xuan Xie, Wen-Feng Zhou, Yan-Chao Hu e Yan-Guang Yang. "Aerothermodynamic characteristics of hypersonic curved compression ramp flows with bistable states". Physics of Fluids 33, n. 12 (dicembre 2021): 126106. http://dx.doi.org/10.1063/5.0069666.

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48

Itoh, Hajime, e Mutsuo Kotake. "Study on Hypersonic Compression Corner Flows Using Glow Discharge-Tracer Technique". JOURNAL OF THE JAPAN SOCIETY FOR AERONAUTICAL AND SPACE SCIENCES 54, n. 631 (2006): 337–44. http://dx.doi.org/10.2322/jjsass.54.337.

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49

Harden, J. L., e M. E. Cates. "Extension and Compression of Grafted Polymer Layers in Strong Normal Flows". Journal de Physique II 5, n. 7 (luglio 1995): 1093–103. http://dx.doi.org/10.1051/jp2:1995226.

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50

Simeonides, G., W. Haase e M. Manna. "Experimental, analytical, and computational methods applied to hypersonic compression ramp flows". AIAA Journal 32, n. 2 (febbraio 1994): 301–10. http://dx.doi.org/10.2514/3.11985.

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