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Analysis of debris flow control effect and hazard assessment in Xinqiao Gully,Wenchuan M_(s)8.0 earthquake area based on numerical simulation 被引量:1
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作者 Chang Yang Yong-bo Tie +3 位作者 Xian-zheng Zhang Yan-feng Zhang Zhi-jie Ning Zong-liang Li 《China Geology》 CAS CSCD 2024年第2期248-263,共16页
Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the eff... Xinqiao Gully is located in the area of the 2008 Wenchuan M_(s)8.0 earthquake in Sichuan province,China.Based on the investigation of the 2023"6-26"Xinqiao Gully debris flow event,this study assessed the effectiveness of the debris flow control project and evaluated the debris flow hazards.Through field investigation and numerical simulation methods,the indicators of flow intensity reduction rate and storage capacity fullness were proposed to quantify the effectiveness of the engineering measures in the debris flow event.The simulation results show that the debris flow control project reduced the flow intensity by41.05%to 64.61%.The storage capacity of the dam decreases gradually from upstream to the mouth of the gully,thus effectively intercepting and controlling the debris flow.By evaluating the debris flow of different recurrence intervals,further measures are recommended for managing debris flow events. 展开更多
关键词 Landslide Debris flow Hazard assessment Numerical simulation OpenLISEM Prevention and control project Wenchuan M_(s)8.0 earthquake Xinqiao Gully Sichuan province Geological hazards survey engineering
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Analysis and experimental study on resistance-increasing behavior of composite high efficiency autonomous inflow control device
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作者 Liang-Liang Dong Yu-Lin Zhang 《Petroleum Science》 SCIE EI CAS CSCD 2024年第2期1290-1304,共15页
Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks th... Bottom water coning is the main reason to reduce the recovery of horizontal bottom water reservoir. By water coning, we mean the oil-water interface changes from a horizontal state to a mound-shaped cone and breaks through to the wellbore. Autonomous inflow control device(AICD) is an important instrument maintain normal production after bottom water coning, however, the resistance increasing ability of the swirl type AICD is insufficient at present, which seriously affects the water control effect. Aiming this problem, this paper designs a multi-stage resistance-increasing and composite type AICD. The separation mechanism of oil-water two phases in this structure, the resistance form of oil-water single phase and the resistance-increasing principle of water phase are analyzed. Establishing the dual-phase multi-stage separation and resistance-increasing model, and verified by measuring the throttling pressure drop and oil-water volume fraction of the AICD, it is found that the composite type AICD has the effect of ICD and AICD at the same time, which can balance the production rate of each well section at the initial stage of production, delay the occurrence of bottom water coning. In the middle and later stages of production, water-blocking can be effectively increased to achieve water control and stable production.After structural sensitivity analysis, the influence law of various structural parameters on the water control performance of composite AICD was obtained. The simulation calculation results show that,compared with the existing swirl type AICD, composite AICD has higher sensitivity to moisture content,the water phase throttling pressure drop is increased by 4.5 times on average. The composite AICD is suitable for the entire stage of horizontal well production. 展开更多
关键词 Water control flow separation flow resistance-increasing AICD device Simulation and experiment
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Research on passenger flow control at metro transfer stations based on real-time flow calculation of streamlines
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作者 Bin Lei Zhuoxing Hou +3 位作者 Yifei Suo Wei Liu Linlin Luo Dongbo Lei 《Railway Sciences》 2024年第6期684-703,共20页
Purpose – The volume of passenger traffic at metro transfer stations serves as a pivotal metric for theorchestration of crowd flow management. Given the intricacies of crowd dynamics within these stations andthe recu... Purpose – The volume of passenger traffic at metro transfer stations serves as a pivotal metric for theorchestration of crowd flow management. Given the intricacies of crowd dynamics within these stations andthe recurrent instances of substantial passenger influxes, a methodology predicated on stochastic processesand the principle of user equilibrium is introduced to facilitate real-time traffic flow estimation within transferstation streamlines.Design/methodology/approach – The synthesis of stochastic process theory with streamline analysisengenders a probabilistic model of intra-station pedestrian traffic dynamics. Leveraging real-time passengerflow data procured from monitoring systems within the transfer station, a gradient descent optimizationtechnique is employed to minimize the cost function, thereby deducing the dynamic distribution of categorizedpassenger flows. Subsequently, adhering to the tenets of user equilibrium, the Frank–Wolfe algorithm isimplemented to allocate the intra-station categorized passenger flows across various streamlines, ascertainingthe traffic volume for each.Findings – Utilizing the Xiaozhai Station of the Xi’an Metro as a case study, the Anylogic simulation softwareis engaged to emulate the intra-station crowd dynamics, thereby substantiating the efficacy of the proposedpassenger flow estimation model. The derived solutions are instrumental in formulating a crowd controlstrategy for Xiaozhai Station during the peak interval from 17:30 to 18:00 on a designated day, yielding crowdmanagement interventions that offer insights for the orchestration of passenger flow and operationalgovernance within metro stations.Originality/value – The construction of an estimation methodology for the real-time streamline traffic flowaugments the model’s dataset, supplanting estimated values derived from surveys or historical datasets withreal-time computed traffic data, thereby enhancing the precision and immediacy of crowd flow managementwithin metro stations. 展开更多
关键词 Metro transfer station Passenger flow control flow streamline Stochastic process User equilibrium
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Mathematical Modeling and Control Algorithm Development for Bidirectional Power Flow in CCS-CNT System
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作者 Sinqobile Wiseman Nene 《Journal of Power and Energy Engineering》 2024年第9期131-143,共12页
As the demand for more efficient and adaptable power distribution systems intensifies, especially in rural areas, innovative solutions like the Capacitor-Coupled Substation with a Controllable Network Transformer (CCS... As the demand for more efficient and adaptable power distribution systems intensifies, especially in rural areas, innovative solutions like the Capacitor-Coupled Substation with a Controllable Network Transformer (CCS-CNT) are becoming increasingly critical. Traditional power distribution networks, often limited by unidirectional flow capabilities and inflexibility, struggle to meet the complex demands of modern energy systems. The CCS-CNT system offers a transformative approach by enabling bidirectional power flow between high-voltage transmission lines and local distribution networks, a feature that is essential for integrating renewable energy sources and ensuring reliable electrification in underserved regions. This paper presents a detailed mathematical representation of power flow within the CCS-CNT system, emphasizing the control of both active and reactive power through the adjustment of voltage levels and phase angles. A control algorithm is developed to dynamically manage power flow, ensuring optimal performance by minimizing losses and maintaining voltage stability across the network. The proposed CCS-CNT system demonstrates significant potential in enhancing the efficiency and reliability of power distribution, making it particularly suited for rural electrification and other applications where traditional methods fall short. The findings underscore the system's capability to adapt to varying operational conditions, offering a robust solution for modern power distribution challenges. 展开更多
关键词 Capacitor Couple Substation Ferroresonance Power flow control controllable Network controller Capacitor-Coupled Substation Incorporating controllable Network Transformer (CCS-CNT) System System Modeling
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A Fuzzy Flow Control Approach for ABR Service in ATM Networks
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作者 张孝林 张飒兵 吴介一 《Journal of Southeast University(English Edition)》 EI CAS 2002年第1期33-39,共7页
The explicit rate flow control mechanisms for ABR service are used to sharethe available bandwidth of a bottleneck link fairly and reasonably among many competitive users andto maintain the buffer queue length of a bo... The explicit rate flow control mechanisms for ABR service are used to sharethe available bandwidth of a bottleneck link fairly and reasonably among many competitive users andto maintain the buffer queue length of a bottleneck switch connected to the link at a desired levelin order to avoid and control congestion in ATM networks. However, designing effective flow controlmechanisms for the service is known to be difficult because of the variety of dynamic parametersinvolved such as available link bandwidth, burst of the traffic, the distances between ABR sourcesand switches. In this paper, we present a fuzzy explicit rate flow control mechanism for ABRservice. The mechanism has a simple structure and is robust in the sense that the mechanism'sstability is not sensitive to the change in the number of active virtual connections (VCs). Manysimulations show that this mechanism can not only effectively avoid network congestion, but alsoensure fair share of the bandwidth for all active VCs regardless of the number of hops theytraverse. Additionally, it has the advantages of fast convergence, low oscillation, and high linkbandwidth utilization. 展开更多
关键词 ATM network congestion prevent flow control fuzzy logic
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Optimization of flow control devices in a single-strand slab continuous casting tundish 被引量:11
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作者 Ning Ding Yan-ping Bao +1 位作者 Qi-song Sun Li-feng Wang 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2011年第3期292-296,共5页
The optimization of flow control devices in a single-slab continuous casting tundish was carried out by physical modeling, and the optimized scheme was presented. With the optimal tundish configuration, the minimum re... The optimization of flow control devices in a single-slab continuous casting tundish was carried out by physical modeling, and the optimized scheme was presented. With the optimal tundish configuration, the minimum residence time of liquid steel was increased by 1.4 times, the peak concentration time was increased by 97%, and the dead volume fraction was decreased by 72%. A mathematical model for molten steel in the tundish was established by using the fluid dynamics package Fluent. The velocity field, concentration field, and the resi-dence time distribution (RTD) curves of molten steel flow before and after optimization were obtained. Experimental results showed that the reasonable configuration with flow control devices can improve the fluid flow characteristics in the tundish. The results of industrial applica-tion show that the nonmetallic inclusion area ratio in casting slabs is decreased by 32% with the optimal tundish configuration. 展开更多
关键词 TUNDISH flow control SIMULATION OPTIMIZATION residence time
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RESEARCH ON THE PERFORMANCE OF NEW TYPE OF PROPORTIONAL PESSURE AND FLOW CONTROL VALVE 被引量:9
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作者 Quan LongMa JianWang YongjinInstitute of Mechatronics,Taiyuan University of Technology,Taiyuan 030024, China 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2003年第3期281-284,共4页
A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control... A new closed loop flow controlling principle through correcting the valve'sopening area while load pressure is changing is carried out. Further more a principle using only oneproportional valve to compound control pressure and flow is suggested. By using very simpleproportional throttle valve in structure, the functions that five kinds of proportional valves orany two of them combined possess can be complimented. After analyzing, comparing, and testing thedynamic and static characteristics of valve with different controlling principles and main valvestructure styles, the optimized structure styles and control methods are achieved. 展开更多
关键词 Electro-hydraulic proportional control Proportional flow valve Proportionalpressure valve Pressure and flow compound control
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Theoretical Analysis and Numerical Simulation of the Static and Dynamic Characteristics of Hydrostatic Guides Based on Progressive Mengen Flow Controller 被引量:13
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作者 GAO Dianrong ZHENG Dan ZHANG Zuochao 《Chinese Journal of Mechanical Engineering》 SCIE EI CAS CSCD 2010年第6期709-716,共8页
The oil film thickness of oil hydrostatic guide with constant pressure supply based on capillary restrictor is greatly affected by load, and this kind of hydrostatic guide is usually applied to the machine tools with ... The oil film thickness of oil hydrostatic guide with constant pressure supply based on capillary restrictor is greatly affected by load, and this kind of hydrostatic guide is usually applied to the machine tools with moderate load. The static and dynamic characteristics of the guide have been studied by using some theoretical, numerical and experimental approaches, and some methods and measures have been proposed to improve its performances. The hydrostatic guide based on progressive mengen(PM) flow controller is especially suitable for the heavy numerical control(NC) machine tools. However, few literatures about the research on the static and dynamic characteristics of the hydrostatic guides based on PM flow controller are reported. In this paper, the formulae are derived for analyzing the static and dynamic characteristics of hydrostatic guides with rectangle pockets and PM flow controller according to the theory of hydrostatic bearing. On the basis of the analysis of hydrostatic bearing with circular pocket, some equations are derived for solving the static pressure, volume pressure and squeezing pressure which influence the dynamic characteristics of hydrostatic guides with rectangle pocket. The function and the influencing factors of three pressures are clarified. The formulae of amplitude-frequency characteristics and dynamic stiffness of the hydrostatic guide system are derived. With the help of software MATLAB, programs are coded with C++ language to simulate numerically the static and dynamic characteristics of the hydrostatic guide based on PM flow controller. The simulation results indicate that the sensitive oil volume between the outlet of the PM flow controller and the guide pocket has the greatest influence on the characteristics of the guide, and it should be reduced as small as possible when the field working condition is met. Choosing the oil with a greater viscosity is also helpful in improving the dynamic performance of hydrostatic guides. The research work has instructing significance for analyzing and designing the guide with PM flow controller. 展开更多
关键词 PM flow controller rectangle pocket static characteristics dynamic characteristics hydrostatic guides
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ASYMMETRIC VORTICES FLOW OVER SLENDER BODY AND ITS ACTIVE CONTROL AT HIGH ANGLE OF ATTACK 被引量:16
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作者 邓学蓥 王延奎 《Acta Mechanica Sinica》 SCIE EI CAS CSCD 2004年第6期567-579,共13页
The studies of asymmetric vortices flow over slender body and its active control at high angles of attack have significant importance for both academic field and engineering area.This paper attempts to provide an upda... The studies of asymmetric vortices flow over slender body and its active control at high angles of attack have significant importance for both academic field and engineering area.This paper attempts to provide an update state of art to the investigations on the fields of forebody asymmetric vortices.This review emphasizes the correlation between micro-perturbation on the model nose and its response and evolution behaviors of the asymmetric vortices.The critical issues are discussed, which include the formation and evolution mechanism of asymmetric multi-vortices;main behaviors of asymmetric vortices flow including its deterministic feature and vortices flow structure;the evolution and development of asymmetric vortices under the perturbation on the model nose;forebody vortex active control especially discussed micro-perturbation active control concept and technique in more detail.However present understanding in this area is still very limited and this paper tries to identify the key unknown problems in the concluding remarks. 展开更多
关键词 asymmetric vortex flow control high angle of attack aerodynamics slender body
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Numerical modelling of structural controls on fluid flow and mineralization 被引量:13
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作者 J.Robinson P.M.Schaubs 《Geoscience Frontiers》 SCIE CAS 2011年第3期449-461,共13页
This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization. We first give an overview of natural phenomena of structurally-controlled ore formation and... This paper presents the results of a set of numerical models focussing on structural controls on hydrothermal mineralization. We first give an overview of natural phenomena of structurally-controlled ore formation and the background theory and mechanisms for such controls. We then provide the results of a group of simple 2D numerical models validated through comparison with Cu-vein structure observed near the Shilu Copper deposit (Yangchun, Guangdong Province, China) and finally a case study of 3D numerical modelling applied to the Hodgkinson Province in North Queensland (Australia). Two modelling approaches, discrete deformation modelling and continuum coupled deformation and fluid flow modelling, are involved. The 2D model-derived patterns are remarkably consistent with the Cu-vein structure from the Shilu Copper deposit, and show that both modelling approaches can realistically simulate the mechanical behaviours of shear and dilatant fractures. The continuum coupled deformation and fluid flow model indicates that pattern of the Cu- veins near the Shilu deposit is the result of shear strain localization, development of dilation and fluid focussing into the dilatant fracture segments. The 3D case-study models (with deformation and fluid flow coupling) on the Hodgkinson Province generated a number of potential gold mineralization 展开更多
关键词 Structural control DILATION Fluid flow MINERALIZATION Numerical modelling Shilu Cu-deposit Hodgkinson Province
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Orthogonal analysis of water model study on the optimization of flow control devices in a six-strand tundish 被引量:18
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作者 Zhengyan Wei Yanping Bao +2 位作者 Jianhua Liu Wenxu Gong Baoming Wang 《Journal of University of Science and Technology Beijing》 CSCD 2007年第2期118-124,共7页
Improper flow control devices in a multi-strand tundish can cause some problems, for example, liquid steel cannot reach every nozzle at the same time and the liquid steel in nozzles far away from the entry zone has a ... Improper flow control devices in a multi-strand tundish can cause some problems, for example, liquid steel cannot reach every nozzle at the same time and the liquid steel in nozzles far away from the entry zone has a lower temperature. The water model experiment of a six-strand tundish of Tianjin Iron & Steel Co. Ltd. was performed, a new "U" type baffle was obtained, and its parameters were defined by perpendicular analysis. The "U" baffle can not only improve those imperfections, but also prolong the residence time of nonmetallic inclusions, which is good for their flotation and separation. 展开更多
关键词 six-strand tundish water model flow control devices OPTIMIZATION
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Improvement of tundish shape and optimization of flow control devices for sequence casting heavy steel ingots 被引量:10
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作者 Guang-hua Wen Yong-feng Huang +1 位作者 Ping Tang Ming-mei Zhu 《International Journal of Minerals,Metallurgy and Materials》 SCIE EI CAS CSCD 2012年第1期15-20,共6页
The metallurgical effect of a round tundish used to cast heavy steel ingots in machine works at present was evaluated through water modeling experiments. The flow control devices of the improved oval tundish, which wa... The metallurgical effect of a round tundish used to cast heavy steel ingots in machine works at present was evaluated through water modeling experiments. The flow control devices of the improved oval tundish, which was used instead of the round tundish, had been optimized. The results show that the residence time of the round tundish is short, its inclusion removal efficiency is too low, and it has more dead zones and an unreasonable flow field. Compared with the round tundish, the improved oval tundish with the optimized weir and dam has a better effect: its minimum residence time is prolonged by 38.1 s, the average residence time is prolonged by 233.4 s, its dead volume fraction decreases from 26% to 15%, and the ratio of plug volume fraction to dead volume fraction increases from 0.54 to 1.27. The inclusion removal efficiency also increases by 17.5%. 展开更多
关键词 TUNDISH steel ingots water modeling flow control devices INCLUSIONS
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NUMERICAL SOLUTION OF VISCOUS FLOW PAST A SOLID SPHERE WITH THE CONTROL VOLUME FORMULATION 被引量:4
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作者 毛在砂 陈家镛 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 1997年第2期13-24,共12页
The control volume formulation with the QUICK finite difference scheme is used to solveincompressible liquid flow past a solid sphere in terms of stream function and vorticity.Several tech-nical points are addressed o... The control volume formulation with the QUICK finite difference scheme is used to solveincompressible liquid flow past a solid sphere in terms of stream function and vorticity.Several tech-nical points are addressed on improving the accuracy and efficiency of numerical simulation of similarproblems of fluid flow.In particular,the importance of suitable specification of the distortion func-tion to enforcing the far field boundarv conditions is emphasized. 展开更多
关键词 SPHERE LAMINAR flow numerical simulation control VOLUME FORMULATION QUICK scheme
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Influence of separator control on the characteristics of severe slugging flow 被引量:4
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作者 Luo Xiaoming He Limin +1 位作者 Liu Xinye Lü Yuling 《Petroleum Science》 SCIE CAS CSCD 2014年第2期300-307,共8页
Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main ... Due to the special structure of offshore multiphase pipes, it is easy for severe slugging to occur in the riser at low gas-liquid velocity. Violent pressure fluctuations and dramatic changes of flow rate are the main characteristics of severe slugging, leading to the risk of serious damage. In this paper, the separator control is adopted to accurately control the separator liquid level and pressure under severe slugging flow conditions. This indicates that the separator liquid level control alone does not have a significant impact on the upstream flow, but it is beneficial for normal operation and pressure control of the separator. As the separator pressure increases, the peak pressure in the riser apparently diminishes, and the amplitude of pressure fluctuation gradually decreases, which means that severe slugging is inhibited. During the slug blowing out, the gas/liquid slipping in the riser intensifies. The long gas plug quickly flows through the riser, and then tends to morph into short and slowly flowing gas bubbles. The elimination effect of the pressure control strategy on severe slugging is related to the relative rate of the superficial gas/liquid flow. 展开更多
关键词 Multiphase flow severe slugging separator control RISER
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Numerical Investigation of Electrohydrodynamic (EHD) Flow Control in an S-Shaped Duct 被引量:7
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作者 杨晖 李锋 +1 位作者 宋耀颖 孙佰刚 《Plasma Science and Technology》 SCIE EI CAS CSCD 2012年第10期897-904,共8页
An electrohydrodynamic (EHD) method, which is based on glow discharge plasma, is presented for flow control in an S-shaped duct. The research subject is an expanding channel with a constant width and a rectangular c... An electrohydrodynamic (EHD) method, which is based on glow discharge plasma, is presented for flow control in an S-shaped duct. The research subject is an expanding channel with a constant width and a rectangular cross section. An equivalent divergence angle and basic function are introduced to build the three-dimensional model. Subsequently, the plasma physical models are simplified as the effects of electrical body force and work (done by the force) on the fluid near the wall. With the aid of FLUENT software, the source terms of momentum and energy are added to the Navier-Stokes equation. Finally, the original performance of three models (A, B and C) is studied, in which model A demonstrates better performance. Then EHD control based on model A is discussed. The results show that the EHD method is an effective way of reducing flow loss and improving uniformity at the duct exit. The innovation in this study is the assessment of the EHD control effect on the flow in an S-shaped duct. Both the parametric modeling of the S-shaped duct and the simplified models of plasma provide valuable information for future research on aircraft inlet ducts. 展开更多
关键词 electro hydrodynamic (EHD) S-shaped duct flow control glow discharge plasma total pressure.
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Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control 被引量:4
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作者 刘玉良 朱杰 罗晓曙 《Chinese Physics B》 SCIE EI CAS CSCD 2009年第9期3772-3776,共5页
Based on the fluid flow time-delayed model proposed by Misra et al in internet congestion control, one modified time-delayed model is presented, where the influence of the communication delay on the router queue lengt... Based on the fluid flow time-delayed model proposed by Misra et al in internet congestion control, one modified time-delayed model is presented, where the influence of the communication delay on the router queue length is investigated in detail. The main advantage of the new model is that its stability domain is larger even without an extra controller. By linear stability analysis and numerical simulation, tbe effectiveness and feasibility of the novel model in internet congestion control are verified. 展开更多
关键词 fluid flow model congestion control time delay Hopf bifurcation
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Numerical study of the turbulent channel flow under space-dependent electromagnetic force control at different Reynolds numbers 被引量:2
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作者 Daiwen JIANG Hui ZHANG +3 位作者 Baochun FAN Zijie ZHAO Jian LI Mingyue GUI 《Applied Mathematics and Mechanics(English Edition)》 SCIE EI CSCD 2019年第4期435-448,共14页
In this paper, the control of turbulent channel flow by space-dependent electromagnetic force and the mechanism of drag reduction are investigated with the direct numerical simulation(DNS) methods for different Reynol... In this paper, the control of turbulent channel flow by space-dependent electromagnetic force and the mechanism of drag reduction are investigated with the direct numerical simulation(DNS) methods for different Reynolds numbers. A formulation is derived to express the relation between the drag and the Reynolds shear stress. With the application of optimal electromagnetic force, the in-depth relations among characteristic structures in the flow field, mean Reynolds shear stress, and the effect of drag reduction for different Reynolds numbers are discussed. The results indicate that the maximum drag reductions can be obtained with an optimal combination of parameters for each case of different Reynolds numbers. The regular quasi-streamwise vortex structures, which appear in the flow field, have the same period with that of the electromagnetic force.These structures suppress the random velocity fluctuations, which leads to the absolute value of mean Reynolds shear stress decreasing and the distribution of that moving away from the wall. Moreover, the wave number of optimal electromagnetic force increases,and the scale of the regular quasi-streamwise vortex structures decreases as the Reynolds number increases. Therefore, the rate of drag reduction decreases with the increase in the Reynolds number since the scale of the regular quasi-streamwise vortex structures decreases. 展开更多
关键词 flow control drag reduction ELECTROMAGNETIC FORCE TURBULENT channel flow
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Metro passenger flow control with station-to-station cooperation based on stop-skipping and boarding limiting 被引量:11
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作者 姜曼 李海鹰 +2 位作者 许心越 徐仕鹏 苗建瑞 《Journal of Central South University》 SCIE EI CAS CSCD 2017年第1期236-244,共9页
Metro passenger flow control problem is studied under given total inbound demand in this work,which considers passenger demand control and train capacity supply.Relevant connotations are analyzed and a mathematical mo... Metro passenger flow control problem is studied under given total inbound demand in this work,which considers passenger demand control and train capacity supply.Relevant connotations are analyzed and a mathematical model is developed.The decision variables are boarding limiting and stop-skipping strategies and the objective is the maximal passenger profit.And a passenger original station choice model based on utility theory is built to modify the inbound passenger distribution among stations.Algorithm of metro passenger flow control scheme is designed,where two key technologies of stopping-station choice and headway adjustment are given and boarding limiting and train stopping-station scheme are optimized.Finally,a real case of Beijing metro is taken for example to verify validity.The results show that in the three scenarios with different ratios of normal trains to stop-skipping trains,the total limited passenger volume is the smallest and the systematic profit is the largest in scenario 3. 展开更多
关键词 METRO passenger flow control stop-skipping boarding limiting passenger original station choice
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Control of Asymmetric Flow Fields of Slender Bodies at High Angle of Attack 被引量:4
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作者 明晓 顾蕴松 《Chinese Journal of Aeronautics》 SCIE EI CAS CSCD 2006年第2期168-174,共7页
The wind tunnel experiments is conducted to get inspiration for understanding the mechanism of the asymmetric flow pattern and developing an innovative flow control technique for a slender body at high angle of attack... The wind tunnel experiments is conducted to get inspiration for understanding the mechanism of the asymmetric flow pattern and developing an innovative flow control technique for a slender body at high angle of attack. The bi-stable situation of the side forces is observed, which could be easily switched by a tiny disturbances either from coming flow or from artificial disturbances at nose tip (including manufacturing defect). In turbulent flows the side forces switched randomly between positive and negative. There exists a hysteresis loop of side force with the rolling angle. A rod in front of the slender body is used to change the vortex pattern, which could be kept even the rod is moved out from the stream. A miniature strake attached to the nose tip of the model can be moved to different circumferential position. When the strake is stationary, the hysteresis loop disappears and the side force does not change with the turbulent fluctuation of coming flow. The results from dynamic measurements of section side force indicates that when the strake swung at lower frequency the side force can follow the cadence of the swinging strake. With increasing frequency, the magnitude of the side force decreases. At still high frequency, the side force diminishes to zero. If the strake is swinging, while the middle position can be changed to different circumferential angle Фs on either left or right side, the side forces can be changed proportionally with the angle Фs. On the basis of the experimental results, the mechanism of the asymmetry is discussed. 展开更多
关键词 high angle of attack asymmetric vortex pattern flow control
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A control volume based finite element method for simulating incompressible two-phase flow in heterogeneous porous media and its application to reservoir engineering 被引量:3
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作者 SADRNEJAD S A GHASEMZADEH H +1 位作者 GHOREISHIAN AMIRI S A MONTAZERI G H 《Petroleum Science》 SCIE CAS CSCD 2012年第4期485-497,共13页
Applying the standard Galerkin finite element method for solving flow problems in porous media encounters some difficulties such as numerical oscillation at the shock front and discontinuity of the velocity field on e... Applying the standard Galerkin finite element method for solving flow problems in porous media encounters some difficulties such as numerical oscillation at the shock front and discontinuity of the velocity field on element faces.Discontinuity of velocity field leads this method not to conserve mass locally.Moreover,the accuracy and stability of a solution is highly affected by a non-conservative method.In this paper,a three dimensional control volume finite element method is developed for twophase fluid flow simulation which overcomes the deficiency of the standard finite element method,and attains high-orders of accuracy at a reasonable computational cost.Moreover,this method is capable of handling heterogeneity in a very rational way.A fully implicit scheme is applied to temporal discretization of the governing equations to achieve an unconditionally stable solution.The accuracy and efficiency of the method are verified by simulating some waterflooding experiments.Some representative examples are presented to illustrate the capability of the method to simulate two-phase fluid flow in heterogeneous porous media. 展开更多
关键词 Finite element method control volume two-phase flow HETEROGENEITY porous media WATERFLOODING
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