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Kim, Jaeheun, and Choongsik Bae. "Emission reduction through internal and low-pressure loop exhaust gas recirculation configuration with negative valve overlap and late intake valve closing strategy in a compression ignition engine." International Journal of Engine Research 18, no. 10 (February 1, 2017): 973–90. http://dx.doi.org/10.1177/1468087417692680.
An investigation was carried out to examine the feasibility of replacing the conventional high-pressure loop/low-pressure loop exhaust gas recirculation with a combination of internal and low-pressure loop exhaust gas recirculation. The main objective of this alternative exhaust gas recirculation path configuration is to extend the limits of the late intake valve closing strategy, without the concern of backpressure caused by the high-pressure loop exhaust gas recirculation. The late intake valve closing strategy improved the conventional trade-off relation between nitrogen oxides and smoke emissions. The gross indicated mean effective pressure was maintained at a similar level, as long as the intake boosting pressure kept changing with respect to the intake valve closing timing. Applying the high-pressure loop exhaust gas recirculation in the boosted conditions yielded concern of the exhaust backpressure increase. The presence of high-pressure loop exhaust gas recirculation limited further intake valve closing retardation when the negative effect of increased pumping work cancelled out the positive effect of improving the emissions’ trade-off. Replacing high-pressure loop exhaust gas recirculation with internal exhaust gas recirculation reduced the burden of such exhaust backpressure and the pumping loss. However, a simple feasibility analysis indicated that a high-efficiency turbocharger was required to make the pumping work close to zero. The internal exhaust gas recirculation strategy was able to control the nitrogen oxides emissions at a low level with much lower O2 concentration, even though the initial in-cylinder temperature was high due to hot residual gas. Retardation of intake valve closing timing and intake boosting contributed to increasing the charge density; therefore, the smoke emission reduced due to the higher air–fuel ratio value exceeding 25. The combination of internal and low pressure loop loop exhaust gas recirculation with late intake valve closing strategy exhibited an improvement on the trade-off relation between nitrogen oxides and smoke emissions, while maintaining the gross indicated mean effective pressure at a comparable level with that of the high-pressure loop exhaust gas recirculation configuration.
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Gautier, N., J. L. Aider, T. Duriez, B. R. Noack, M. Segond, and M. Abel. "Closed-loop separation control using machine learning." Journal of Fluid Mechanics 770 (April 10, 2015): 442–57. http://dx.doi.org/10.1017/jfm.2015.95.
We present the first closed-loop separation control experiment using a novel, model-free strategy based on genetic programming, which we call ‘machine learning control’. The goal is to reduce the recirculation zone of backward-facing step flow at $\mathit{Re}_{h}=1350$ manipulated by a slotted jet and optically sensed by online particle image velocimetry. The feedback control law is optimized with respect to a cost functional based on the recirculation area and a penalization of the actuation. This optimization is performed employing genetic programming. After 12 generations comprised of 500 individuals, the algorithm converges to a feedback law which reduces the recirculation zone by 80 %. This machine learning control is benchmarked against the best periodic forcing which excites Kelvin–Helmholtz vortices. The machine learning control yields a new actuation mechanism resonating with the low-frequency flapping mode instability. This feedback control performs similarly to periodic forcing at the design condition but outperforms periodic forcing when the Reynolds number is varied by a factor two. The current study indicates that machine learning control can effectively explore and optimize new feedback actuation mechanisms in numerous experimental applications.
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Alekseev, É. I., E. N. Bazarov, V. P. Gubin, V. G. Kovalenko, A. I. Sazonov, and N. I. Starostin. "Recirculation fiber loop interferometer with a Faraday reflector." Technical Physics Letters 28, no. 11 (November 2002): 949–51. http://dx.doi.org/10.1134/1.1526893.
Araiza-Martínez, Enrique, Javier Ortiz-Villafuerte, and Rogelio Castillo-Durán. "A detailed BWR recirculation loop model for RELAP." Nuclear Engineering and Design 311 (January 2017): 1–8. http://dx.doi.org/10.1016/j.nucengdes.2016.11.006.
Markina, L. M., N. Yr Zholobenko, and S. Yr Ushcats. "Investigation of the influence of the physicochemical characteristics of waste on the quality of liquid fuel products from them, obtained by multi-loop recirculation pyrolysis." Journal of Achievements in Materials and Manufacturing Engineering 1, no. 106 (May 1, 2021): 20–33. http://dx.doi.org/10.5604/01.3001.0015.0526.
Purpose: To study the properties of MSW generated in Ukraine in order to ensure their most efficient processing using the multi-loop recirculation pyrolysis technology in order produce a liquid fuel product. Design/methodology/approach: The problem' study of MSW accumulation in the world countries was carried out on the basis scientific databases PubMed, ScienceDirect, Mendeley, ResearchGate, Google Scholar for the corresponding keywords. The MSW properties generated in Ukraine were determined in accordance with the current standards to determine the specific properties of materials. For the experimental study, 3 types of solid organic waste mixtures were compiled, the composition of which characterizes the variable data on the accumulation of household and industrial waste of Ukraine. The quantity and quality of the liquid product obtained was determined using certified equipment. Findings: The tests revealed that the composition of the solid organic waste mixture when disposing of them by the multi-loop recirculation pyrolysis method has little effect the composition and properties of the obtained liquid hydrocarbon product; the total time of complete degradation for different mixtures of composite materials (mixtures of polymeric substances) is 180-250 min; the correct selection of the temperature of the circulation system makes it possible to produce a gaseous or liquid product which can then be used as an alternative fuel. Research limitations/implications: Current study of solid organic waste degradation was carried out by the multi-loop recirculation pyrolysis method. The experimental waste mixtures did not contain very wet waste of small fractions. Practical implications: The technology of circulating pyrolysis makes it possible to change the qualitative and quantitative composition of the obtained liquid hydrocarbon product, which is a potential fuel, irrespective of the composition of the solid organic waste mixture.Originality/value: It has been experimentally established that the quality of the liquid hydrocarbon product obtained by the multi-loop recirculation pyrolysis process does not depend on the composition of the solid organic waste mixture, but depends on the process' duration and the third circuit' temperature of the multi-loop recirculation system.
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Liu, Yu, and Shibao Wu. "Proposed Scheme for Ultra-Flat Optical Frequency Comb Generation Based on Dual-Drive Mach–Zehnder Modulators and Bidirectional Recirculating Frequency Shifting in Single Loop." Photonics 9, no. 8 (July 24, 2022): 514. http://dx.doi.org/10.3390/photonics9080514.
Recirculating frequency shifting has attracted much attention for its advantages in the generation of the flexible and high-quality optical frequency comb. A new scheme of ultra-flat optical frequency comb generation system based on single-loop bidirectional recirculating frequency shift is proposed and studied in this paper. The generation system employs two pairs of dual-drive Mach–Zehnder modulators and several polarization devices. Compared with the method of single-loop unidirectional recirculation frequency shift, under the same cycles, the number of comb lines generated by the proposed method is doubled, and the generated optical frequency combs have less noise accumulation and better flatness. The theoretical model is established, and the proposed scheme is verified by software simulation. A 111-line optical frequency comb with the spacing of 12.5 GHz, the flatness of 0.76 dB, and the optical signal-to-noise ratio of 27.39 dB was obtained by adopting the proposed scheme.
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van Benthum, W. A. J., R. G. J. M. van der Lans, M. C. M. van Loosdrecht, and J. J. Heijnen. "Bubble recirculation regimes in an internal-loop airlift reactor." Chemical Engineering Science 54, no. 18 (September 1999): 3995–4006. http://dx.doi.org/10.1016/s0009-2509(99)00097-4.
Sheintuch, Moshe, and Olga Nekhamkina. "Comparison of flow-reversal, internal-recirculation and loop reactors." Chemical Engineering Science 59, no. 19 (October 2004): 4065–72. http://dx.doi.org/10.1016/j.ces.2004.04.037.
Braun, D., and W. Gujer. "Reactive tracers reveal hydraulic and control instabilities in full-scale activated sludge plant." Water Science and Technology 57, no. 7 (April 1, 2008): 1001–7. http://dx.doi.org/10.2166/wst.2008.210.
The hydraulic characteristics of aeration tanks in WWTPs have a major impact on the degradation of pollutants, as well as on the control of the aeration. In particular in long reactors, which are not separated by baffles, hydraulic shortcuts or large scale recirculation can lead to a loss of performance. This work demonstrates that reactive tracers such as ammonium and oxygen can be used to investigate the hydraulics of aeration tanks in detail. With the use of electrochemical sensors it is possible to investigate effects in a broad range of time scales. In the present case study a slow oscillation of the aeration control loop was investigated. Large scale recirculation in the aeration tank and fast fluctuations of the ammonium concentrations close to the oxygen sensor were identified as the cause of these oscillations. Both, the recirculation as well as the fluctuation of the ammonium have a substantial influence on the performance of the aeration tank and the aeration control loop.
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Kalmani, S. D., A. V. Joshi, G. Majumder, N. K. Mondal, and R. R. Shinde. "Design validation and performance of closed loop gas recirculation system." Journal of Instrumentation 11, no. 11 (November 21, 2016): C11026. http://dx.doi.org/10.1088/1748-0221/11/11/c11026.
Haber, Benjamin. "A Robust Control Approach on Diesel Engines with Dual-Loop Exhaust Gas Recirculation Systems." The Ohio State University, 2010. http://rave.ohiolink.edu/etdc/view?acc_num=osu1274191066.
de, Souza Althea Caroline. "The use of computational fluid dynamics to simulate the flow in a high recirculation airlift reactor." Thesis, University of Portsmouth, 2000. https://researchportal.port.ac.uk/portal/en/theses/the-use-of-computational-fluid-dynamics-to-simulate-the-flow-in-a-high-recirculation-airlift-reactor(2dd55384-1826-4ef9-8f01-3b6f8e86aaee).html.
Sutherland, Erika Susanne. "Analysis of the performance and stability of a passive recirculation loop for hydrogen delivery to a PEM fuel cell system." Digital WPI, 2011. https://digitalcommons.wpi.edu/etd-theses/443.
Proton Exchange Membrane (PEM) fuel cells are becoming an increasingly important alternative to combustion engines as the fossil fuel reserves are depleted. Several papers have presented steady state analyses of the system, but few are known to present dynamic analysis of the flow and control of the hydrogen delivery process. This thesis presents the dynamic analysis of hydrogen delivery to a PEM fuel cell system. The hydrogen is delivered to the anode with use of an ejector for passive recirculation. The system to be studied consists of the manifolds, ejector, and pressure control valve. Models describing the elements of the anode delivery systems are formulated. The governing nonlinear equations are solved analytically and numerically, and the regimes of stable hydrogen delivery process are established. The linearized models are used for performance analysis and optimization of the hydrogen delivery process. The nonlinear model is used to improve the simulation of the dynamics of the PEM fuel cell system and validate the parameters at optimal linearized stability. Experiments are conducted to find the parameters used in the model, as well as validate the results. Both the linear and nonlinear models are implemented in Simulink and tested against the laboratory data from the PEM fuel cell system. The analysis showed that the models have the same time constant and dynamic behavior as the PEM system. The optimal parameters for stability and a faster response with no oscillations in the output are obtained. The redesigned valve and resulting dynamics of the PEM fuel cell system provides improved system performance.
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Le, Maout-Alvarez Coralie. "Étude expérimentale des effets chimiques sur le colmatage des filtres dans l’industrie nucléaire." Electronic Thesis or Diss., Université de Lorraine, 2023. http://docnum.univ-lorraine.fr/ulprive/DDOC_T_2023_0015_ALVAREZ.pdf.
Lors d'un accident de type APRP (Accident de Perte du Réfrigérant Primaire) survenant dans réacteur nucléaire à eau pressurisé (REP), des débris sont générés et ils peuvent être partiellement transportés jusqu'aux filtres des systèmes de secours RIS-EAS des puisards situés dans le fond de l'enceinte de confinement du réacteur. Ces débris peuvent contribuer au colmatage « physique » des filtres. Un autre effet dit « effet chimique » correspond à l'apport de cations en solution de par la corrosion des débris (fibres d'isolant) et la possible corrosion de surfaces métalliques présentes dans le bâtiment réacteur. Ces cations métalliques peuvent former des précipités au sein du lit fibreux formés et accentuer le colmatage physique. En cas d'accident grave avec fusion du cœur, des charges additionnelles de débris sont à considérer comme la présence de particules formées de matériaux de structure, des barres de commande et de produits de fission et des particules de béton résultant d'un interaction corium-béton. Il a été clairement identifié dans la littérature que ces effets chimiques sont à prendre en compte pour s'assurer de la fonction recirculation sur une longue période. La question de recherche est d'être en mesure de comprendre la nature de ces effets chimiques, les paramètres les conditionnant et leurs ampleurs. Le sujet de thèse porte sur l'étude de ces effets chimiques, pour cela une approche paramétrique sera suivie en couplant plusieurs mesures chimiques et en corrélant ces mesures à une perte de charge. Les mesures chimiques en solution se feront principalement par ICP et la caractérisation des précipités potentiellement formés pourra se faire par des analyses type MEB-EDX, DRX et XPS. La boucle de filtration est à concevoir During a LOCA accident (Loss Of Coolant Accident) occurring to a nuclear Pressurized Water Reactor (PWR), debris are generated and can be partially transported to the RIS-EAS filter in the sumps located in the bottom of the nuclear reactor containment. These debris can contribute to the « physical » clogging of the filters. Another effect called « chemical effects » corresponds to the presence of cations in solution resulting from the debris' corrosion and the possible corrosion of the metal surface present in the reactor containment vessel. In the case of a severe accident with core fuel meltdown, additional loads debris are to be considered as presence of particles formed of structural materials, control rod material, fission products and concrete particles resulting from corium-concrete interaction. To ensure the long term liquid recirculation functionality, the chemical effect have to be understood: nature of these chemical effects, conditioning parameters and potential effect on the clogging. The thesis aims at studying the chemical effects after designing a dedicated experimental loop: a parametric approach , coupled with several chemical and pressure drop measurements. Chemical speciation in solution and precipitate characterizations will/can be respectively performed by ICP and MEB-EDX, DRX and XPS techniques
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McCoy, Kenneth A. "A recirculating optical loop for short-term data storage." Diss., Georgia Institute of Technology, 1996. http://hdl.handle.net/1853/14871.
Wijewardane, M. Anusha. "Exhaust system energy management of internal combustion engines." Thesis, Loughborough University, 2012. https://dspace.lboro.ac.uk/2134/9829.
Today, the investigation of fuel economy improvements in internal combustion engines (ICEs) has become the most significant research interest among the automobile manufacturers and researchers. The scarcity of natural resources, progressively increasing oil prices, carbon dioxide taxation and stringent emission regulations all make fuel economy research relevant and compelling. The enhancement of engine performance solely using incylinder techniques is proving increasingly difficult and as a consequence the concept of exhaust energy recovery has emerged as an area of considerable interest. Three main energy recovery systems have been identified that are at various stages of investigation. Vapour power bottoming cycles and turbo-compounding devices have already been applied in commercially available marine engines and automobiles. Although the fuel economy benefits are substantial, system design implications have limited their adaptation due to the additional components and the complexity of the resulting system. In this context, thermo-electric (TE) generation systems, though still in their infancy for vehicle applications have been identified as attractive, promising and solid state candidates of low complexity. The performance of these devices is limited to the relative infancy of materials investigations and module architectures. There is great potential to be explored. The initial modelling work reported in this study shows that with current materials and construction technology, thermo-electric devices could be produced to displace the alternator of the light duty vehicles, providing the fuel economy benefits of 3.9%-4.7% for passenger cars and 7.4% for passenger buses. More efficient thermo-electric materials could increase the fuel economy significantly resulting in a substantially improved business case. The dynamic behaviour of the thermo-electric generator (TEG) applied in both, main exhaust gas stream and exhaust gas recirculation (EGR) path of light duty and heavy duty engines were studied through a series of experimental and modelling programs. The analyses of the thermo-electric generation systems have highlighted the need for advanced heat exchanger design as well as the improved materials to enhance the performance of these systems. These research requirements led to the need for a systems evaluation technique typified by hardware-in-the-loop (HIL) testing method to evaluate heat exchange and materials options. HIL methods have been used during this study to estimate both the output power and the exhaust back pressure created by the device. The work has established the feasibility of a new approach to heat exchange devices for thermo-electric systems. Based on design projections and the predicted performance of new materials, the potential to match the performance of established heat recovery methods has been demonstrated.
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Guimpelson, Bronislav. "BWR coolant chemistry studies using a recirculating in-pile loop." Thesis, Massachusetts Institute of Technology, 1995. http://hdl.handle.net/1721.1/36949.
Mikhailov, Vitaly. "Investigation of high-speed, wavelength-division-multiplexed (WDM) optical fibre transmission systems and devices using recirculating loop techniques." Thesis, University College London (University of London), 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.406136.
Battistini, Lorenzo. "Impact of future EU7 regulations on high performance gasoline-ICEs and possible innovative technologies for extension of lambda 1 operating range." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2022. http://amslaurea.unibo.it/25674/.
The aim of pollutant emissions legislation is to bring environmental benefit by helping reduce, for what road transport is responsible, the concentration of pollutants where levels are too high and endanger human health.
Europe is considering several changes in “post Euro 6d” regulation from 2025. Several measures have been proposed for Euro 7, most of which introduce new challenges in the development of high-performance turbocharged gasoline engine such as the extension of lambda 1 in the whole engine map.
In this Master Thesis, possible technologies to expand the engine operating range with lambda 1 in the entire engine map, without widely reducing the engine performances are analyzed. In particular the focus is on the Pre-Chamber Spark Ignition (PCSI), the Exhaust Gas Recirculation (EGR), the Miller Cylce, the Water Injection and the Ultra High Pressure Injection.
Subsequently, the modeling and validation in Simulink/Matlab of thermal models to analyze and monitor the exhaust gas temperature in the entire exhaust system is presented and explained. The aim of the modeling is integrating the modules into the Model-in-the-Loop environment and co-simulating with GT-Power/Simulink for a virtual pre-calibration of exhaust gas temperature control.
Finally, homologation cycles are run to obtain a first analysis feedback regarding the pre-calibration and to understand which are the cycle zones where the fuel enrichement will be necessary to reach the desired temperature.
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Zhang, Jiejun. "Photonic Dispersive Delay Line for Broadband Microwave Signal Processing." Thesis, Université d'Ottawa / University of Ottawa, 2017. http://hdl.handle.net/10393/35866.
The development of communications technologies has led to an ever-increasing requirement for a wider bandwidth of microwave signal processing systems. To overcome the inherent electronic speed limitations, photonic techniques have been developed for the processing of ultra-broadband microwave signals. A dispersive delay line (DDL) is able to introduce different time delays to different spectral components, which are used to implement signal processing functions, such as time reversal, time delay, dispersion compensation, Fourier transformation and pulse compression. An electrical DDL is usually implemented based on a surface acoustic wave (SAW) device or a synthesized C-sections microwave transmission line, with a bandwidth limited to a few GHz. However, an optical DDL can have a much wider bandwidth up to several THz. Hence, an optical DDL can be used for the processing of an ultra-broadband microwave signal. In this thesis, we will focus on using a DDL based on a linearly chirped fiber Bragg grating (LCFBG) for the processing of broadband microwave signals. Several signal processing functions are investigated in this thesis. 1) A broadband and precise microwave time reversal system using an LCFBG-based DDL is investigated. By working in conjunction with a polarization beam splitter, a wideband microwave waveform modulated on an optical pulse can be temporally reversed after the optical pulse is reflected by the LCFBG for three times thanks to the opposite dispersion coefficient of the LCFBG when the optical pulse is reflected from the opposite ends. A theoretical bandwidth as large as 273 GHz can be achieved for the time reversal. 2) Based on the microwave time reversal using an LCFBG-based DDL, a microwave photonic matched filter is implemented for simultaneously generating and compressing an arbitrary microwave waveform. A temporal convolution system for the calculation of real time convolution of two wideband microwave signals is demonstrated for the first time. 3) The dispersion of an LCFBG is determined by its physical length. To have a large dispersion coefficient while maintaining a short physical length, we can use an optical recirculating loop incorporating an LCFBG. By allowing a microwave waveform to travel in the recirculating loop multiple times, the microwave waveform will be dispersed by the LCFBG multiple times, and the equivalent dispersion will be multiple times as large as that of a single LCFBG. Based on this concept, a time-stretch microwave sampling system with a record stretching factor of 32 is developed. Thanks to the ultra-large dispersion, the system can be used for single-shot sampling of a signal with a bandwidth up to a THz. The study in using the recirculating loop for the stretching of a microwave waveform with a large stretching factor is also performed. 4) Based on the dispersive loop with an extremely large dispersion, a photonic microwave arbitrary waveform generation system is demonstrated with an increased the time-bandwidth product (TBWP). The dispersive loop is also used to achieve tunable time delays by controlling the number of round trips for the implementation of a photonic true time delay beamforming system.
Книги з теми "Recirculation loop":
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Holman, Garry S. Application of reliability techniques to prioritize BWR recirculation loop welds for in-service inspection. Washington, DC: Division of Engineering, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, 1989.
Holland, John H. 4. Agents, networks, degree, and recirculation. Oxford University Press, 2014. http://dx.doi.org/10.1093/actrade/9780199662548.003.0004.
‘Agents, networks, degree, and recirculation’ explains that when studying complex adaptive systems (CAS) in a grammar-like way, agents serve as the ‘alphabet’. The hierarchical organization of CAS implies different kinds of agents at different levels, with correspondingly different grammars. The interactions of signal-processing agents at a point in time can be specified by a network—a snapshot of the agents’ performance capability. The combination of high fanout (the richness of an agent’s interactions) and hierarchical organization results in complex networks that include large numbers of sequences that form loops. More complex loops allow the CAS to ‘look ahead’, examining the effects of various action sequences without actually executing the actions.
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Holland, John H. 7. Co-evolution and the formation of niches. Oxford University Press, 2014. http://dx.doi.org/10.1093/actrade/9780199662548.003.0007.
What is a niche? ‘Co-evolution and the formation of niches’ explains that the term ‘niche’ is widely used to describe an important part of the hierarchical organization of complex adaptive systems: local use of signals and resources. Using Markov processes, a mathematical theory of niches can be formed that allows for multiple species with interaction networks that involve loops and recirculation. When realistic niches are considered, the diversity of the niche dwellers stands out. We see a complicated recirculation of resources and signals. How did this complex network of interactions evolve? The short answer is co-evolution through recombination of building blocks, often accompanied by an exaggeration of some of the resulting characteristics.
Частини книг з теми "Recirculation loop":
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Hsieh, Ying-Jiun, and Yavuz A. Bozer. "Analytical Modeling of Closed-Loop Conveyors with Load Recirculation." In Computational Science and Its Applications – ICCSA 2005, 437–47. Berlin, Heidelberg: Springer Berlin Heidelberg, 2005. http://dx.doi.org/10.1007/11424925_47.
Kalmani, S. D., Surya Mondal, R. R. Shinde, and P. V. Hunagund. "Some Studies Using Capillary for Flow Control in a Closed Loop Gas Recirculation System." In XXII DAE High Energy Physics Symposium, 913–15. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-73171-1_223.
Prończuk, Mateusz, and Katarzyna Bizon. "The Influence of External Recirculation Loop Design on the Hydrodynamic Properties of a Hybrid Fluidized Bed Apparatus." In Practical Aspects of Chemical Engineering, 346–54. Cham: Springer International Publishing, 2020. http://dx.doi.org/10.1007/978-3-030-39867-5_36.
Ivanov, Sergei I., Alexander P. Lavrov, Dmitrii V. Kondakov, and Yurij A. Matveev. "Fiber-Optic Recirculating Memory Loop for Wideband Microwave Signal." In Lecture Notes in Computer Science, 254–67. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-97777-1_22.
Hamaide, J. P., B. Biotteau, F. Pitel, and E. Desurvire. "Soliton Wavelength-Division-Multiplexing Systems: From Numerical Design to Recirculating Loop Experiments." In Optical Solitons: Theoretical Challenges and Industrial Perspectives, 171–82. Berlin, Heidelberg: Springer Berlin Heidelberg, 1999. http://dx.doi.org/10.1007/978-3-662-03807-9_10.
Kondakov, Dmitrii V., Sergei I. Ivanov, and Alexander P. Lavrov. "A Broadband Analog Fiber-Optic Line with Recirculating Memory Loop for Variable Microwave Signal Delay." In Springer Proceedings in Physics, 487–96. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-81119-8_53.
Ben Amira, Bilel, Mariem Ammar, Ahmad Kaffel, Zied Driss, and Mohamed Salah Abid. "The Effects of Curved Blade Turbine on the Hydrodynamic Structure of a Stirred Tank." In Vortex Dynamics Theories and Applications. IntechOpen, 2020. http://dx.doi.org/10.5772/intechopen.92394.
This work is aimed at studying the hydrodynamic structure in a cylindrical stirred vessel equipped with an eight-curved blade turbine. Flow fields were measured by two-dimensional particle image velocimetry (PIV) to evaluate the effect of the curved blade turbine. Velocity field, axial and radial velocity distribution, root mean square (rms) of the velocity fluctuations, vorticity, and turbulent kinetic energy were presented. Therefore, two recirculation loops were formed close to the free surface and in the bottom of the tank. Moreover, the highest value area of the vorticity is localized in the upper region of the tank which follows the same direction of the first circulation loop. The turbulent kinetic energy is maximum at the blade tip following the trailing vortices.
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Paschotta, R. "recirculating fiber loops." In RP Photonics Encyclopedia. RP Photonics AG, 2004. http://dx.doi.org/10.61835/aq4.
"Scott and Tabibi phase into the other by feeding it into the vicinity of the mixing/dispersing element. In this way, the phase being added is quickly dispersed into the continuous phase. Although it is widely accepted that the higher the shear rate produced by the mixer the smaller the droplets and, hence, the more stable the emulsion, there is a major prob-lem that must be avoided if good results are to be obtained with high-speed mixing equipment. Every effort should be made to avoid incorporating air into the mix. Air forms a third phase that could ruin emulsion stability in a number of ways. Air usu-ally reduces the viscosity. The addition steps should be organized such that the impel-ler of the mixture is always submerged deeply enough to avoid surface turbulence or splashing. The arrangement of the mixer angle and/or baffles should avoid vortexing. Another alternative is to perform all of the emulsion-making steps in a vacuum-pro-cessing vessel. An additional method is to premix the components at low speeds and shear rates and then subsequently execute the high-shear portion of the process with in-line equipment in the absence of air. In short, aeration should be avoided. Sometimes the direct approach is not the most effective one. When one phase is first added to another, the small amount of liquid being added forms the internal phase. If more of this liquid is added there comes a point where the continuous phase loses its ability to hold all of the internal phase and the emulsion inverts to the opposite type, e.g., from O/W to W/O. Since it has been found that this practice (phase inversion) can yield small droplet sizes, this method is widely used in batch processing. To ex-ecute this maneuver, one needs to begin mixing with only a small amount of liquid in a batch that will later increase to usually more than four times the starting volume. Therefore, the mixer has to extend well to the bottom of the vessel. One way to avoid this small volume of starting liquid is by using an in-line mixer in a recirculation loop attached to the main mixing vessel as illustrated in Fig. 5. The initial phase is recirculated through the in-line high mixer and the phase to be inverted is then carefully metered directly into the recirculation line. This avoids Fig. 5 In-line mixer in recirculation loop to kettle." In Pharmaceutical Dosage Forms, 326–33. CRC Press, 1998. http://dx.doi.org/10.1201/9781420000955-37.
"put capacity and does not require premixing; it is fairly inexpensive and suitable for continuous operation. Major drawbacks to this equipment are its lack of availability, the need for special heating and cooling control systems, no available laboratory model, and the need for many trial-and-error runs in order to scale-up to production. 8. Static Mixers A true low-shear and low-energy requirement device for emulsifying immiscible liq-uid mixtures is the static mixer. Sometimes called a pipeline mixer, this device is ac-tually a series of specially designed baffles in a cylindrical pipe as shown in Fig. 42. These simple devices are used extensively for the preparation of unstable emulsions for liquid-liquid extraction purposes. Droplet sizes, obtainable using static mixers, have been studied extensively and vary with viscosity, interfacial tension, pressure drop, and static mixer design [45]. Size distributions obtainable range from 1000-100 |am. Hence, al-though there are very few emulsions stable in this region, the static mixer has seen application as an in-line premixer in continuous processes or in recirculation loops to batch-processing equipment. F. Nonmechanical Disperse Processing Recently a new processing technique became available for the production of stable and uniform liposomes. It uses the physico-chemical properties of the supercritical liquids rather than the mechanical forces of the pumps. One such a process technology is pre-sented in this section. 1. Critical Fluids Liposome Process Near-critical or supercritical fluid solvents with or without polar cosolvents (SuperFluids™) (Aphios, Corp., Woburn, MA) for the formation of uniform and stable liposomes having high encapsulation efficiencies has been used [46-48]. Supercritical or near-critical fluids as shown by the pressure-temperature diagram in Fig. 43, are gases such as carbon dioxide and propane that have been processed under ambient conditions. When compressed at conditions above their critical temperature and pres-sure, these substances become fluids with liquidlike density and the ability to dissolve other materials, and gaslike properties of low viscosity and high diffusivity. The gas-eous characteristics increase mass transfer rates, thereby significantly reducing process-ing time. Small added amounts of miscible polar cosolvents, such as alcohol, can be used to adjust polarity and to maximize the selectivity and capacity of the solvent. Fig. 42 Static mixer. (From Ref. 44.)." In Pharmaceutical Dosage Forms, 370–75. CRC Press, 1998. http://dx.doi.org/10.1201/9781420000955-56.
Strazisar, Anthony J., Michelle M. Bright, Scott Thorp, Dennis E. Culley, and Kenneth L. Suder. "Compressor Stall Control Through Endwall Recirculation." In ASME Turbo Expo 2004: Power for Land, Sea, and Air. ASMEDC, 2004. http://dx.doi.org/10.1115/gt2004-54295.
Experiments that demonstrate the use of endwall recirculation to control the stall of transonic compressor stages are described. Endwall recirculation of a compressor stage is implemented by bleeding air from the casing downstream of a stator blade row and injecting the air as a wall jet upstream of a preceding rotor blade row. The bleed ports, injection ports, and recirculation channels are circumferentially discrete, and occupy only 20–30% of the circumference. The development of compact wall-jet injectors is described first. Next, the results of proof-of-concept steady recirculation tests on a single-stage transonic compressor are presented. Finally, the potential for using endwall recirculation to increase the stability of transonic highly-loaded multistage compressors is demonstrated through results from a rig test of simulated recirculation driving both a steady injected flow and an unsteady injected flow commanded by closed-loop active control during compressor operation at 78–100% of design speed. In this test air from an external source was injected upstream of several rotor blade rows while compressor bleed was increased by an amount equivalent to the injected massflow. During closed loop control, wall static pressure fluctuations were monitored and the injected flow rate was controlled to reduce the stalling mass flow. The use of wall jet injection to study the dynamics of transonic compressor stages is also discussed.
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Hwang, Sheng-Dih, and Te-Chuan Wang. "Identify the Broken Loop and Break Sizes of Recirculation Line LOCA for a BWR6/MarkIII Plant." In 2020 International Conference on Nuclear Engineering collocated with the ASME 2020 Power Conference. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/icone2020-16089.
Abstract In this study, the MAAP5 code was used as the tool to simulate a reactor operated at steady-state and occurred an LOCA with different break sizes at the recirculation loops. A BWR6/MarkIII nuclear power plant (NPP) was selected as the sample deck. By detecting the temperature difference between the loops, and then the break size could be determined including which loop and how is the break size. Moreover, this study had also analyzed the effect of break sizes affecting the characteristic of an NPP. These results were consistent with the previous experiments and codes. This study also suggested to the operators in the main control room (MCR), when they observed some syndrome of the acquired data and they could preliminary estimate which loop broke and how was the size of the LOCA. Those could help the operators to make a strategy to avoid the probability of core melted.
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Vieth, Jonathan, Marcel Reith-Braun, Albert Bauer, Florian Pfaff, Georg Maier, Robin Gruna, Thomas Längle, Harald Kruggel-Emden, and Uwe D. Hanebeck. "Improving Accuracy of Optical Sorters Using Closed-Loop Control of Material Recirculation." In 2023 American Control Conference (ACC). IEEE, 2023. http://dx.doi.org/10.23919/acc55779.2023.10156014.
James A Hardin, C L Jones, E L Bonjour, R T Noyes, R L Beeby, D A Eltiste, and S Decker. "Ozone Fumigation of Stored Grain; Closed-loop Recirculation and Rate of Ozone Consumption." In 2009 Reno, Nevada, June 21 - June 24, 2009. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2009. http://dx.doi.org/10.13031/2013.27354.
Haber, Benjamin, and Junmin Wang. "Robust Control Approach on Diesel Engines With Dual-Loop Exhaust Gas Recirculation Systems." In ASME 2010 Dynamic Systems and Control Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/dscc2010-4135.
This paper presents a robust control approach to achieve an independent control authority over the intake manifold conditions of a medium-duty, V8, Diesel engine with the use of a complex air-path system. The intake manifold conditions in question include gas temperature, pressure, and oxygen mass fraction. The purpose of achieving such a high control authority over these intake manifold conditions is to explore the possibilities of extending the operating ranges of advanced combustion modes like low temperature diffusion combustion (LTDC), homogenous charge compression ignition (HCCI), and pre-mixed charge compression ignition (PCCI). Independent control of these air-path variables is made possible by using a dual-loop exhaust gas recirculation (EGR) system with a two-stage, variable geometry turbocharging (VGT) system. A multi-input-multi-output robust air-path controller was designed based on a control-oriented model identified using a high-fidelity GT-Power model of a medium-duty Diesel engine. Simulation results illustrate the effectiveness of the controller over a limited engine operating range.
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COLAFRANCESCHI, Stefano, Raffaella AURILIO, Luigi Benussi, Stefano Bianco, Mauro Ferrini, Tommaso GRECI, Luciano Passamonti, et al. "Tests of gas contaminants and interaction with materials in closed loop recirculation systems." In XI Workshop on Resistive Plate Chambers and Related Detectors. Trieste, Italy: Sissa Medialab, 2012. http://dx.doi.org/10.22323/1.159.0056.
Pu, Yifan, Xiuyuan Sun, Zhongyang Xu, and Shilong Pan. "Impacts of Modulation Instability in a Fiber Recirculation Loop Used for Photonics-Assisted Microwave Pulse Replication." In 2022 Asia Communications and Photonics Conference (ACP). IEEE, 2022. http://dx.doi.org/10.1109/acp55869.2022.10088738.
Koli, Rohit, Harikesh Arunachalam, Qilun Zhu, Simona Onori, Ardalan Vahidi, and Robert Prucka. "Nonlinear Model Predictive Control of Dual Loop - Exhaust Gas Recirculation in a Turbocharged Spark Ignited engine." In 2018 Annual American Control Conference (ACC). IEEE, 2018. http://dx.doi.org/10.23919/acc.2018.8430853.
Walker, Andy, Fariborz Mahjouri, and Robert Stiteler. "Evacuated Tube Heat Pipe Solar Collectors Applied to Recirculation Loop in a Federal Building: SSA Philadelphia." In ASME 2004 International Solar Energy Conference. ASMEDC, 2004. http://dx.doi.org/10.1115/isec2004-65132.
This paper describes design, simulation, construction and measured initial performance of a solar water heating system (360 Evacuated Heat-Pipe Collector tubes, 54 m2 gross area, 36 m2 net absorber area) installed at the top of the hot water recirculation loop in the Social Security Mid-Atlantic Center in Philadelphia. Water returning to the hot water storage tank is heated by the solar array when solar energy is available. This new approach, as opposed to the more conventional approach of preheating incoming water, is made possible by the thermal diode effect of heat pipes and low heat loss from evacuated tube solar collectors. The simplicity of this approach and its low installation costs makes the deployment of solar energy in existing commercial buildings more attractive, especially where the roof is far removed from the water heating system, which is often in the basement. Initial observed performance of the system is reported. Hourly simulation estimates annual energy delivery of 111 GJ/year of solar heat and that the annual efficiency (based on the 54 m2 gross area) of the solar collectors is 41%, and that of the entire system including parasitic pump power, heat loss due to freeze protection, and heat loss from connecting piping is 34%. Annual average collector efficiency based on a net aperture area of 36 m2 is 61.5% according to the hourly simulation.
Звіти організацій з теми "Recirculation loop":
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Holman, G. Application of reliability techniques to prioritize BWR (boiling water reactor) recirculation loop welds for in-service inspection. Office of Scientific and Technical Information (OSTI), December 1989. http://dx.doi.org/10.2172/5193479.
Willner, Allan E., and Paniz Ebrahimi. Using a Recirculating Fiber Loop to Determine the Limitations Placed on Ultra-High-Performance Soliton and Linear Optical Systems by Polarization Mode Dispersion. Fort Belvoir, VA: Defense Technical Information Center, May 2003. http://dx.doi.org/10.21236/ada416674.
Yin, Yan. Final Report: A Multi-Channel Recirculating Loop Signal Regenerator for High Frequency Single-Shot Bunch Length Measurement, August 13, 1998 - March 17, 1999. Office of Scientific and Technical Information (OSTI), June 1999. http://dx.doi.org/10.2172/765220.
