WorldWideScience

Sample records for griswald flow control

  1. Flow Control

    Science.gov (United States)

    2013-04-08

    can be written as â fj (t) =WO tanh( WIx (t)+bI)+bO, (38) where WI , WO are the input and output matrices, respectively, and bI and bO are the input...applications, present on envisioned airborne optical platforms . One of the problems is that all adaptive optical systems rely on mechanically moving some...of successfully controlling the optical aberration due to the flow over the aperture of airborne optical platforms . As outlined above, systems

  2. Intelligent Flow Control Valve

    Science.gov (United States)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  3. Distributed Power Flow Controller

    NARCIS (Netherlands)

    Yuan, Z.

    2010-01-01

    In modern power systems, there is a great demand to control the power flow actively. Power flow controlling devices (PFCDs) are required for such purpose, because the power flow over the lines is the nature result of the impedance of each line. Due to the control capabilities of different types of

  4. Defining Quantum Control Flow

    OpenAIRE

    Ying, Mingsheng; Yu, Nengkun; Feng, Yuan

    2012-01-01

    A remarkable difference between quantum and classical programs is that the control flow of the former can be either classical or quantum. One of the key issues in the theory of quantum programming languages is defining and understanding quantum control flow. A functional language with quantum control flow was defined by Altenkirch and Grattage [\\textit{Proc. LICS'05}, pp. 249-258]. This paper extends their work, and we introduce a general quantum control structure by defining three new quantu...

  5. Fluid flow control system

    International Nuclear Information System (INIS)

    Rion, Jacky.

    1982-01-01

    Fluid flow control system featuring a series of grids placed perpendicular to the fluid flow direction, characterized by the fact that it is formed of a stack of identical and continuous grids, each of which consists of identical meshes forming a flat lattice. The said meshes are offset from one grid to the next. This system applies in particular to flow control of the coolant flowing at the foot of an assembly of a liquid metal cooled nuclear reactor [fr

  6. Content dependent information flow control

    DEFF Research Database (Denmark)

    Nielson, Hanne Riis; Nielson, Flemming

    2017-01-01

    Information flow control extends access control by not only regulating who is allowed to access what data but also the subsequent use of the data. Applications within communications systems require such information flow control to be dependent on the actual contents of the data. We develop...

  7. Flow Control Technology

    Science.gov (United States)

    2010-07-01

    known as Darrieus turbines or, after the German inventors of these devices, Voith-Schneider propellers. Their main advantage is the ability to produce... turbines (VAWT), named for the typical orientation of the main shaft. While their efficiency is similar to that of the more common horizontal axis wind ...Oscillating Systems’, Cambridge University Press, 2002 [11] G. M. Darrieus , ’ Turbine having its rotating shaft transverse to the flow of the current

  8. Flow Control Enabled Aircraft Design

    National Research Council Canada - National Science Library

    Nangia, Rajendar

    2004-01-01

    ...: Many future advanced aircraft concepts being considered by the Air Force fall outside the current aerodynamic design practice and will rely heavily on the use of flow control technology to optimize flight performance...

  9. Optimal Power Flow Control by Rotary Power Flow Controller

    Directory of Open Access Journals (Sweden)

    KAZEMI, A.

    2011-05-01

    Full Text Available This paper presents a new power flow model for rotary power flow controller (RPFC. RPFC injects a series voltage into the transmission line and provides series compensation and phase shifting simultaneously. Therefore, it is able to control the transmission line impedance and the active power flow through it. An RPFC is composed mainly of two rotary phase shifting transformers (RPST and two conventional (series and shunt transformers. Structurally, an RPST consists of two windings (stator and rotor windings. The rotor windings of the two RPSTs are connected in parallel and their stator windings are in series. The injected voltage is proportional to the vector sum of the stator voltages and so its amplitude and angle are affected by the rotor position of the two RPSTs. This paper, describes the steady state operation and single-phase equivalent circuit of the RPFC. Also in this paper, a new power flow model, based on power injection model of flexible ac transmission system (FACTS controllers, suitable for the power flow analysis is introduced. Proposed model is used to solve optimal power flow (OPF problem in IEEE standard test systems incorporating RPFC and the optimal settings and location of the RPFC is determined.

  10. Subcubic Control Flow Analysis Algorithms

    DEFF Research Database (Denmark)

    Midtgaard, Jan; Van Horn, David

    We give the first direct subcubic algorithm for performing control flow analysis of higher-order functional programs. Despite the long held belief that inclusion-based flow analysis could not surpass the ``cubic bottleneck, '' we apply known set compression techniques to obtain an algorithm...... that runs in time O(n^3/log n) on a unit cost random-access memory model machine. Moreover, we refine the initial flow analysis into two more precise analyses incorporating notions of reachability. We give subcubic algorithms for these more precise analyses and relate them to an existing analysis from...

  11. Controls on summer low flow

    Science.gov (United States)

    Graham, C. B.; McNamara, J. P.

    2012-12-01

    Summer low flow has significant impacts on aquatic flora and fauna, municipal water use, and power generation. However, the controls on the minimum annual summer discharge are complex, including a combination of snowmelt dynamics, summer evapotranspiration demand, and spring, summer precipitation patterns and surface - groundwater interactions. This is especially true in the Rocky Mountain West of the United States, where snowpack provides the majority of water available for spring runoff and groundwater replenishment. In this study, we look at summer low flow conditions at four snow dominated catchments (26 km2 - 2200 km2) in South-central Idaho currently feeling the effects of climate change. Measures of snowmelt dynamics, summer evapotranspiration demand and spring and summer precipitation are used to determine the dominant controls on late summer low flow magnitude, timing and duration. These analyses show that the controls vary between watersheds, with significant implications for the impacts of climate change in snow dominated areas of the Rocky Mountain West.

  12. Flow control arrangements for centrifuges

    International Nuclear Information System (INIS)

    Alderton, G.W.; Davidge, P.C.

    1983-01-01

    In a centrifuge plant for the separation of uranium isotopes, when a centrifuge machine breaks down, light gas is produced. This gas can cause adjacent machines to break down, so propagating the fault. The present invention provides flow control arrangements in gas pipes to the centrifuge, whereby sudden egress of gas from a failed machine is inhibited. (author)

  13. Multiverse data-flow control.

    Science.gov (United States)

    Schindler, Benjamin; Waser, Jürgen; Ribičić, Hrvoje; Fuchs, Raphael; Peikert, Ronald

    2013-06-01

    In this paper, we present a data-flow system which supports comparative analysis of time-dependent data and interactive simulation steering. The system creates data on-the-fly to allow for the exploration of different parameters and the investigation of multiple scenarios. Existing data-flow architectures provide no generic approach to handle modules that perform complex temporal processing such as particle tracing or statistical analysis over time. Moreover, there is no solution to create and manage module data, which is associated with alternative scenarios. Our solution is based on generic data-flow algorithms to automate this process, enabling elaborate data-flow procedures, such as simulation, temporal integration or data aggregation over many time steps in many worlds. To hide the complexity from the user, we extend the World Lines interaction techniques to control the novel data-flow architecture. The concept of multiple, special-purpose cursors is introduced to let users intuitively navigate through time and alternative scenarios. Users specify only what they want to see, the decision which data are required is handled automatically. The concepts are explained by taking the example of the simulation and analysis of material transport in levee-breach scenarios. To strengthen the general applicability, we demonstrate the investigation of vortices in an offline-simulated dam-break data set.

  14. Liquid-Flow Controller With Trickle Preflow

    Science.gov (United States)

    Cox, George B., Jr.

    1990-01-01

    Liquid-flow controller allows pressure in liquid to increase steeply with flow as flow starts, then provides more-gradual nearly linear rise of pressure with flow as flow and pressure increase beyond preset breakpoint. Controller alternative version of mechanism described in "Liquid-Flow Controller Responds To Pressure" (MFS-28329) and "Liquid-Flow Controller With Preset Break Pressure" (MFS-28330). Material cut out of cone at tip of pintle. Liquid always passes from shell, albeit at low rate. When pressure in shell great enough to force orifice away from pintle, liquid flows at greater rate.

  15. Bypass flow rate control method

    International Nuclear Information System (INIS)

    Kiyama, Yoichi.

    1997-01-01

    In a PWR type reactor, bypass flow rate is controlled by exchanging existent jetting hole plugs of a plurality of nozzles disposed to the upper end of incore structures in order to flow a portion of primary coolants as a bypass flow to the upper portion of the pressure vessel. Two kinds of exchange plugs, namely, a first plug and a second plug each having a jetting out hole of different diameter are used as exchange plugs. The first plug has the diameter as that of an existent plug and the second plug has a jetting out hole having larger diameter than that of the existent plug. Remained extent plugs are exchanged to a combination of the first and the second plugs without exchanging existent plugs having seizing with the nozzles, in which the number and the diameter of the jetting out holes of the second plugs are previously determined based on predetermined total bypass flow rate to be jetted from the entire plugs after exchange of plugs. (N.H.)

  16. Bio-mimetic Flow Control

    Science.gov (United States)

    Choi, Haecheon

    2009-11-01

    Bio-mimetic engineering or bio-mimetics is the application of biological methods and systems found in nature to the study and design of engineering systems and modern technology (from Wikipedia). The concept itself is old, but successful developments have been made recently, especially in the research field of flow control. The objective of flow control based on the bio-mimetic approach is to develop novel concepts for reducing drag, increasing lift and enhancing aerodynamic performance. For skin friction reduction, a few ideas have been suggested such as the riblet from shark, compliant surface from dolphin, microbubble injection and multiple front-body curvature from penguin, and V-shaped protrusion from sailfish. For form drag reduction, several new attempts have been also made recently. Examples include the V-shaped spanwise grooves from saguaro cactus, overall shape of box fish, longitudinal grooves on scallop shell, bill of swordfish, hooked comb on owl wing, trailing-edge protrusion on dragonfly wing, and fillet. For the enhancement of aerodynamic performance, focuses have been made on the birds, fish and insects: e.g., double layered feather of landing bird, leading-edge serration of humpback-whale flipper, pectoral fin of flying fish, long tail on swallowtail-butterfly wing, wing flapping motion of dragonfly, and alula in birds. Living animals adapt their bodies to better performance in multi purposes, but engineering requires single purpose in most cases. Therefore, bio-mimetic approaches often produce excellent results more than expected. However, they are sometimes based on people's wrong understanding of nature and produce unwanted results. Successes and failures from bio-mimetic approaches in flow control will be discussed in the presentation.

  17. The Control of Junction Flows

    National Research Council Canada - National Science Library

    Smith, Charles

    1997-01-01

    An experimental study of the effects of spatially-limited (i.e. localized) surface suction on unsteady laminar and turbulent junction flows was performed using hydrogen bubble flow visualization and Particle Image Velocimetry (PIV...

  18. Electromagnetic application device for flow rate/flow speed control

    International Nuclear Information System (INIS)

    Yoshioka, Senji.

    1994-01-01

    Electric current and magnetic field are at first generated in a direction perpendicular to a flow channel of a fluid, and forces generated by electromagnetic interaction of the current and the magnetic field are combined and exerted on the fluid, to control the flow rate and the flow speed thereby decreasing flowing pressure loss. In addition, an electric current generation means and a magnetic field generation means integrated together are disposed to a structural component constituting the flow channel, and they are combined to attain the aimed effect. The current generating means forms a potential difference by supplying electric power to a pair of electrodes as a cathode and an anode by using structures disposed along the channel, to generate an electric field or electric current in a direction perpendicular to the flow channel. The magnetic field generating means forms a counter current (reciprocal current) by using structures disposed along the flow channel, to generate synthesized or emphasized magnetic field. The fluid can be applied with a force in the direction of the flowing direction by the electromagnetic interaction of the electric current and the magnetic field, thereby capable of propelling the fluid. Accordingly, the flowrate/flowing speed can be controlled inside of the flow channel and flowing pressure loss can be decreased. (N.H.)

  19. Power flow control using quadrature boosters

    Science.gov (United States)

    Sadanandan, Sandeep N.

    A power system that can be controlled within security constraints would be an advantage to power planners and real-time operators. Controlling flows can lessen reliability issues such as thermal limit violations, power stability problems, and/or voltage stability conditions. Control of flows can also mitigate market issues by reducing congestion on some lines and rerouting power to less loaded lines or onto preferable paths. In the traditional control of power flows, phase shifters are often used. More advanced methods include using Flexible AC Transmission System (FACTS) Controllers. Some examples include Thyristor Controlled Series Capacitors, Synchronous Series Static Compensators, and Unified Power Flow Controllers. Quadrature Boosters (QBs) have similar structures to phase-shifters, but allow for higher voltage magnitude during real power flow control. In comparison with other FACTS controllers QBs are not as complex and not as expensive. The present study proposes to use QBs to control power flows on a power system. With the inclusion of QBs, real power flows can be controlled to desired scheduled values. In this thesis, the linearized power flow equations used for power flow analysis were modified for the control problem. This included modifying the Jacobian matrix, the power error vector, and calculating the voltage injected by the quadrature booster for the scheduled real power flow. Two scenarios were examined using the proposed power flow control method. First, the power flow in a line in a 5-bus system was modified with a QB using the method developed in this thesis. Simulation was carried out using Matlab. Second, the method was applied to a 30-bus system and then to a 118-bus system using several QBs. In all the cases, the calculated values of the QB voltages led to desired power flows in the designated line.

  20. Flow control for oblique shock wave reflections

    OpenAIRE

    Giepman, R.H.M.

    2016-01-01

    Shock wave-boundary layer interactions are prevalent in many aerospace applications that involve transonic or supersonic flows. Such interactions may lead to boundary layer separation, flow unsteadiness and substantial losses in the total pressure. Flow control techniques can help to mitigate these adverse effects and stabilize the interaction. This thesis focuses on passive flow control techniques for oblique shock wave reflections on flat plates and presents experimental results for both la...

  1. A novel micromechanical flow controller

    NARCIS (Netherlands)

    van Toor, M.W.; van Toor, M.W.; Lammerink, Theodorus S.J.; Gardeniers, Johannes G.E.; Elwenspoek, Michael Curt; Monsma, D.J.

    A new concept for a micromechanical flow regulator is presented. Regulation of the flow is achieved using variation of channel length instead of channel diameter. Several design concepts together with their application in fluidic systems are presented. A regulator for biomedical use, as a part of a

  2. Flow control for oblique shock wave reflections

    NARCIS (Netherlands)

    Giepman, R.H.M.

    2016-01-01

    Shock wave-boundary layer interactions are prevalent in many aerospace applications that involve transonic or supersonic flows. Such interactions may lead to boundary layer separation, flow unsteadiness and substantial losses in the total pressure. Flow control techniques can help to mitigate these

  3. Modular Control Flow Analysis for Libraries

    DEFF Research Database (Denmark)

    Probst, Christian W.

    2002-01-01

    One problem in analyzing object oriented languages is that the exact control flow graph is not known statically due to dynamic dispatching. However, this is needed in order to apply the large class of known interprocedural analysis. Control Flow Analysis in the object oriented setting aims...

  4. Flow Control in a Compact Inlet

    Science.gov (United States)

    Vaccaro, John C.

    2011-12-01

    An experimental investigation of flow control, via various control jets actuators, was undertaken to eliminate separation and secondary flows in a compact inlet. The compact inlet studied was highly aggressive with a length-to-diameter ratio of 1.5. A brand new facility was designed and built to enable various actuation methodologies as well as multiple measurement techniques. Techniques included static surface pressure, total pressure, and stereoscopic particle image velocimetry. Experimental data were supplemented with numerical simulations courtesy of Prof. Kenneth Jansen, Dr. Onkar Sahni, and Yi Chen. The baseline flow field was found to be dominated by two massive separations and secondary flow structures. These secondary structures were present at the aerodynamic interface plane in the form of two counter-rotating vortices inducing upwash along centerline. A dominant shedding frequency of 350 Hz was measured both at the aerodynamic interface plane and along the lower surface of the inlet. Flow control experiments started utilizing a pair of control jets placed in streamwise locations where flow was found to separate. Tests were performed for a range of inlet Mach numbers from 0.2 to 0.44. Steady and unsteady static pressure measurements along the upper and lower walls of the duct were performed for various combinations of actuation. The parameters that were tested include the control jets momentum coefficient, their blowing ratio, the actuation frequency, as well as different combinations of jets. It was shown that using mass flux ratio as a criterion to define flow control is not sufficient, and one needs to provide both the momentum coefficient and the blowing ratio to quantify the flow control performance. A detailed study was undertaken on controlling the upstream separation point for an inlet Mach number of 0.44. Similar to the baseline flow field, the flow field associated with the activation of a two-dimensional control jet actuator was dominated by

  5. Integrated soft sensor model for flow control.

    Science.gov (United States)

    Aijälä, G; Lumley, D

    2006-01-01

    Tighter discharge permits often require wastewater treatment plants to maximize utilization of available facilities in order to cost-effectively reach these goals. Important aspects are minimizing internal disturbances and using available information in a smart way to improve plant performance. In this study, flow control throughout a large highly automated wastewater treatment plant (WWTP) was implemented in order to reduce internal disturbances and to provide a firm foundation for more advanced process control. A modular flow control system was constructed based on existing instrumentation and soft sensor flow models. Modules were constructed for every unit process in water treatment and integrated into a plant-wide model. The flow control system is used to automatically control recirculation flows and bypass flows at the plant. The system was also successful in making accurate flow estimations at points in the plant where it is not possible to have conventional flow meter instrumentation. The system provides fault detection for physical flow measuring devices. The module construction allows easy adaptation for new unit processes added to the treatment plant.

  6. Flow Control of Flexible Structures

    Science.gov (United States)

    2017-09-06

    levels of modeling [Dowell and Hall, 2001]. Fur- thermore, even for the most complex models, the main research goal has been a mathe - matical description...possibility for localized, discrete actuation to coun- teract detrimental flow developments before they result in significant structural loads and

  7. Efficiency improvements of electromagnetic flow control

    International Nuclear Information System (INIS)

    Spong, E.; Reizes, J.A.; Leonardi, E.

    2005-01-01

    In turbulent flow, frictional resistance and heat transfer are controlled to a large degree by the intensity of the turbulence fluctuations in the near vicinity of a surface. In the case of a weak electrically conducting fluid, such as seawater, turbulence intensity can be controlled by subjecting the fluid to electromagnetic fields. This technique, known as Electro-magneto-hydro-dynamic (EMHD) flow control, has been shown to have promise as a means of reducing the turbulence intensity, and hence heat transfer or frictional drag of turbulent boundary layers. Unfortunately EMHD flow control currently suffers from poor efficiency due to the high energy requirements of the electromagnetic field. A numerical study has been conducted in which a new electromagnetic actuator design has been developed to provide a more efficient spatial distribution of the electromagnetic forces. The new actuator design has then been coupled to an ideal flow sensor. A flow control subroutine, embedded in the numerical model, uses the velocity information from the ideal sensor to determine the appropriate actuating force to apply to the flow at each time step. The new actuator design has been shown to be capable of successfully attenuating a sequence of artificial low speed streaks in a simplified model of a low Reynolds number turbulent boundary layer. Thus, a potential solution to the poor efficiency of EMHD flow control has been offered by providing the means whereby the expensive electromagnetic forces can be strategically and sparingly applied to the flow

  8. Manipulation of vortex rings for flow control

    International Nuclear Information System (INIS)

    Toyoda, Kuniaki; Hiramoto, Riho

    2009-01-01

    This paper reviews the dynamics of vortex rings and the control of flow by the manipulation of vortex rings. Vortex rings play key roles in many flows; hence, the understanding of the dynamics of vortex rings is crucial for scientists and engineers dealing with flow phenomena. We describe the structures and motions of vortex rings in circular and noncircular jets, which are typical examples of flows evolving into vortex rings. For circular jets the mechanism of evolving, merging and breakdown of vortex rings is described, and for noncircular jets the dynamics of three-dimensional deformation and interaction of noncircular vortex rings under the effect of self- and mutual induction is discussed. The application of vortex-ring manipulation to the control of various flows is reviewed with successful examples, based on the relationship between the vortex ring dynamics and the flow properties. (invited paper)

  9. Compressed-air flow control system.

    Science.gov (United States)

    Bong, Ki Wan; Chapin, Stephen C; Pregibon, Daniel C; Baah, David; Floyd-Smith, Tamara M; Doyle, Patrick S

    2011-02-21

    We present the construction and operation of a compressed-air driven flow system that can be used for a variety of microfluidic applications that require rapid dynamic response and precise control of multiple inlet streams. With the use of inexpensive and readily available parts, we describe how to assemble this versatile control system and further explore its utility in continuous- and pulsed-flow microfluidic procedures for the synthesis and analysis of microparticles.

  10. The art and science of flow control

    Science.gov (United States)

    Gad-El-hak, Mohamed

    1989-01-01

    The ability to actively or passively manipulate a flow field to effect a desired change is of immense technological importance. In this article, methods of control to achieve transition delay, separation postponement, lift enhancement, drag reduction, turbulence augmentation, or noise suppression are considered. Emphasis is placed on external boundary-layer flows although applicability of some of the methods reviewed for internal flows will be mentioned. Attempts will be made to present a unified view of the different methods of control to achieve a variety of end results. Performance penalties associated with a particular method such as cost, complexity, or trade-off will be elaborated.

  11. A Lyapunov theory based UPFC controller for power flow control

    Energy Technology Data Exchange (ETDEWEB)

    Zangeneh, Ali; Kazemi, Ahad; Hajatipour, Majid; Jadid, Shahram [Center of Excellence for Power Systems Automation and Operation, Iran University of Science and Technology, Tehran (Iran)

    2009-09-15

    Unified power flow controller (UPFC) is the most comprehensive multivariable device among the FACTS controllers. Capability of power flow control is the most important responsibility of UPFC. According to high importance of power flow control in transmission lines, the proper controller should be robust against uncertainty and disturbance and also have suitable settling time. For this purpose, a new controller is designed based on the Lyapunov theory and its stability is also evaluated. The Main goal of this paper is to design a controller which enables a power system to track reference signals precisely and to be robust in the presence of uncertainty of system parameters and disturbances. The performance of the proposed controller is simulated on a two bus test system and compared with a conventional PI controller. The simulation results show the power and accuracy of the proposed controller. (author)

  12. Monitoring And Controlling Hydroponic Flow

    Science.gov (United States)

    Dreschel, Thomas W.

    1992-01-01

    Pressure-monitoring and -controlling apparatus maintains slight suction required on nutrient solution in apparatus described in "Tubular Membrane Plant-Growth Unit" (KSC-11375), while overcoming gravity effects on operation of system on Earth. Suction helps to hold solution in tubular membrane.

  13. Recycle flow rate control device

    International Nuclear Information System (INIS)

    Sumida, Susumu; Mizuno, Hiroshi; Oka, Yoko.

    1984-01-01

    Purpose: To attain stable low hydraulic power operation with no abnormal changes in the reactor water level by smoothly varying the speed control for the recycling pump for regulating the reactor core flowrate in BWR type reactors. Constitution: In a recycling control system equipped with an internal pump having a response characteristic higher by ten and several times or more than that of prior pump, a previously programed recycling run-back signal is inputted to a speed regulator upon load interruption of the electric generator to thereby control the operation of the internal pump driving motor such that the speed is decreased rapidly at the initial state and smoothly thereafter. The run-back singal is passed through a primary delay circuit so that the interruption of the motor operation does not directly performed by the signal interruption upon failure. As the result, the amount of void produced is also made smooth and the reactor water level varies smoothly as well, whereby the reactor power can be reduced with a sufficient margin. (Kamimura, M.)

  14. Modelling and control of systems with flow

    NARCIS (Netherlands)

    van Mourik, S.

    2008-01-01

    In practice, feedback control design consists of three steps: modelling, model reduction and controller design for the reduced model. Systems with flow are often complicated, and there is yet no standard algorithm that integrates these steps. In this thesis we make a modest effort by considering two

  15. Numerical study of MHD supersonic flow control

    Science.gov (United States)

    Ryakhovskiy, A. I.; Schmidt, A. A.

    2017-11-01

    Supersonic MHD flow around a blunted body with a constant external magnetic field has been simulated for a number of geometries as well as a range of the flow parameters. Solvers based on Balbas-Tadmor MHD schemes and HLLC-Roe Godunov-type method have been developed within the OpenFOAM framework. The stability of the solution varies depending on the intensity of magnetic interaction The obtained solutions show the potential of MHD flow control and provide insights into for the development of the flow control system. The analysis of the results proves the applicability of numerical schemes, that are being used in the solvers. A number of ways to improve both the mathematical model of the process and the developed solvers are proposed.

  16. Locus of control in relation to flow

    Directory of Open Access Journals (Sweden)

    Celeste M Taylor

    2006-04-01

    Full Text Available The principal objective of the study was to examine the relationship between locus of control and optimal experience (flow in carrying out work and/or study activities. Two questionnaires measuring the aforementioned constructs were administered to a group of first and second-year Human Resource Management students (n=168 between the ages of 16 and 30. The results suggest that more frequent experience of flow is positively correlated with Autonomy and Internal Locus of Control. Limitations, lines of future research, implications and further contributions are discussed.

  17. Coordinated Control of Cross-Flow Turbines

    Science.gov (United States)

    Strom, Benjamin; Brunton, Steven; Polagye, Brian

    2016-11-01

    Cross-flow turbines, also known as vertical-axis turbines, have several advantages over axial-flow turbines for a number of applications including urban wind power, high-density arrays, and marine or fluvial currents. By controlling the angular velocity applied to the turbine as a function of angular blade position, we have demonstrated a 79 percent increase in cross-flow turbine efficiency over constant-velocity control. This strategy uses the downhill simplex method to optimize control parameter profiles during operation of a model turbine in a recirculating water flume. This optimization method is extended to a set of two turbines, where the blade motions and position of the downstream turbine are optimized to beneficially interact with the coherent structures in the wake of the upstream turbine. This control scheme has the potential to enable high-density arrays of cross-flow turbines to operate at cost-effective efficiency. Turbine wake and force measurements are analyzed for insight into the effect of a coordinated control strategy.

  18. Declarative flow control for distributed instrumentation

    Energy Technology Data Exchange (ETDEWEB)

    Parvin, Bahram; Taylor, John; Fontenay, Gerald; Callahan, Daniel

    2001-06-01

    We have developed a 'microscopy channel' to advertise a unique set of on-line scientific instruments and to let users join a particular session, perform an experiment, collaborate with other users, and collect data for further analysis. The channel is a collaborative problem solving environment (CPSE) that allows for both synchronous and asynchronous collaboration, as well as flow control for enhanced scalability. The flow control is a declarative feature that enhances software functionality at the experimental scale. Our testbed includes several unique electron and optical microscopes with applications ranging from material science to cell biology. We have built a system that leverages current commercial CORBA services, Web Servers, and flow control specifications to meet diverse requirements for microscopy and experimental protocols. In this context, we have defined and enhanced Instrument Services (IS), Exchange Services (ES), Computational Services (CS), and Declarative Services (DS) that sit on top of CORBA and its enabling services (naming, trading, security, and notification) IS provides a layer of abstraction for controlling any type of microscope. ES provides a common set of utilities for information management and transaction. CS provides the analytical capabilities needed for online microscopy. DS provides mechanisms for flow control for improving the dynamic behavior of the system.

  19. Fuel cell with internal flow control

    Science.gov (United States)

    Haltiner, Jr., Karl J.; Venkiteswaran, Arun [Karnataka, IN

    2012-06-12

    A fuel cell stack is provided with a plurality of fuel cell cassettes where each fuel cell cassette has a fuel cell with an anode and cathode. The fuel cell stack includes an anode supply chimney for supplying fuel to the anode of each fuel cell cassette, an anode return chimney for removing anode exhaust from the anode of each fuel cell cassette, a cathode supply chimney for supplying oxidant to the cathode of each fuel cell cassette, and a cathode return chimney for removing cathode exhaust from the cathode of each fuel cell cassette. A first fuel cell cassette includes a flow control member disposed between the anode supply chimney and the anode return chimney or between the cathode supply chimney and the cathode return chimney such that the flow control member provides a flow restriction different from at least one other fuel cell cassettes.

  20. Design and Realization of Intelligent Flow Controller

    Directory of Open Access Journals (Sweden)

    Jianxiong Ye

    2014-09-01

    Full Text Available According to accurate flow rate control requirements in large irrigation zone, a fuzzy controller with dead-band is designed on the characteristics analysis and comparison of PID and Fuzzy. The setting values of water flow for gates are determined by real-time water level detection sensors, and the realistic value of discharged water and gate opening are detected out with relative sensors, simulation manifest that the specific control strategy can adjust the gate swiftly in circumstance of huge offset, and regulate the gate slightly in time of small bias, it is realized with Siemens S315 PLC (Programmable Logical Controller and has being working steadily for 2 years, the aim of regulation is performed properly.

  1. Control Flow Analysis for BioAmbients

    DEFF Research Database (Denmark)

    Nielson, Flemming; Nielson, Hanne Riis; Priami, C.

    2007-01-01

    This paper presents a static analysis for investigating properties of biological systems specified in BioAmbients. We exploit the control flow analysis to decode the bindings of variables induced by communications and to build a relation of the ambients that can interact with each other. We...

  2. X-29 vortex flow control tests

    Science.gov (United States)

    Hancock, Regis; Fullerton, Gordon

    1992-01-01

    A joint Air Force/NASA X-29 aircraft program to improve yaw control at high angle of attack using vortex flow control (VFC) is described. Directional VFC blowing proved to a be a powerful yaw moment generator and was very effective in overriding natural asymmetries, but was essentially ineffective in suppressing wing rock. Symmetric aft blowing also had little effect on suppressing wing rock.

  3. Core flow control system for field applications; Sistema de controle de core-flow

    Energy Technology Data Exchange (ETDEWEB)

    Granzotto, Desiree G.; Adachi, Vanessa Y.; Bannwart, Antonio C.; Moura, Luiz F.M. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil); Sassim, Natache S.D.A. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Centro de Estudo do Petroleo (CEPETRO); Carvalho, Carlos H.M. [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The significant heavy oil reserves worldwide and the presently high crude oil prices make it essential the development of technologies for heavy oil production and transportation. Heavy oils, with their inherent features of high viscosity (100- 10,000 cP) and density (below 20 deg API) require specific techniques to make it viable their flow in pipes at high flow rates. One of the simplest methods, which do not require use of heat or diluents, is provided by oil-water annular flow (core-flow). Among the still unsolved issues regarding core-flow is the two-phase flow control in order to avoid abrupt increases in the pressure drop due to the possible occurrence of bad water-lubricated points, and thus obtain a safe operation of the line at the lowest possible water-oil ratio. This work presents results of core flow tests which allow designing a control system for the inlet pressure of the line, by actuating on the water flow rate at a fixed oil flow rate. With the circuit model and the specified controller, simulations can be done to assess its performance. The experiments were run at core-flow circuit of LABPETRO-UNICAMP. (author)

  4. Plasma actuators for bluff body flow control

    Science.gov (United States)

    Kozlov, Alexey V.

    The aerodynamic plasma actuators have shown to be efficient flow control devices in various applications. In this study the results of flow control experiments utilizing single dielectric barrier discharge plasma actuators to control flow separation and unsteady vortex shedding from a circular cylinder in cross-flow are reported. This work is motivated by the need to reduce landing gear noise for commercial transport aircraft via an effective streamlining created by the actuators. The experiments are performed at Re D = 20,000...164,000. Circular cylinders in cross-flow are chosen for study since they represent a generic flow geometry that is similar in all essential aspects to a landing gear oleo or strut. The minimization of the unsteady flow separation from the models and associated large-scale wake vorticity by using actuators reduces the radiated aerodynamic noise. Using either steady or unsteady actuation at ReD = 25,000, Karman shedding is totally eliminated, turbulence levels in the wake decrease significantly and near-field sound pressure levels are reduced by 13.3 dB. Unsteady actuation at an excitation frequency of St D = 1 is found to be most effective. The unsteady actuation also has the advantage that total suppression of shedding is achieved for a duty cycle of only 25%. However, since unsteady actuation is associated with an unsteady body force and produces a tone at the actuation frequency, steady actuation is more suitable for noise control applications. Two actuation strategies are used at ReD = 82,000: spanwise and streamwise oriented actuators. Near field microphone measurements in an anechoic wind tunnel and detailed study of the near wake using LDA are presented in the study. Both spanwise and streamwise actuators give nearly the same noise reduction level of 11.2 dB and 14.2 dB, respectively, and similar changes in the wake velocity profiles. The contribution of the actuator induced noise is found to be small compared to the natural shedding

  5. Drag Reduction by Laminar Flow Control

    Directory of Open Access Journals (Sweden)

    Nils Beck

    2018-01-01

    Full Text Available The Energy System Transition in Aviation research project of the Aeronautics Research Center Niedersachsen (NFL searches for potentially game-changing technologies to reduce the carbon footprint of aviation by promoting and enabling new propulsion and drag reduction technologies. The greatest potential for aerodynamic drag reduction is seen in laminar flow control by boundary layer suction. While most of the research so far has been on partial laminarization by application of Natural Laminar Flow (NLF and Hybrid Laminar Flow Control (HLFC to wings, complete laminarization of wings, tails and fuselages promises much higher gains. The potential drag reduction and suction requirements, including the necessary compressor power, are calculated on component level using a flow solver with viscid/inviscid coupling and a 3D Reynolds-Averaged Navier-Stokes (RANS solver. The effect on total aircraft drag is estimated for a state-of-the-art mid-range aircraft configuration using preliminary aircraft design methods, showing that total cruise drag can be halved compared to today’s turbulent aircraft.

  6. Arduino control of a pulsatile flow rig.

    Science.gov (United States)

    Drost, S; de Kruif, B J; Newport, D

    2018-01-01

    This note describes the design and testing of a programmable pulsatile flow pump using an Arduino micro-controller. The goal of this work is to build a compact and affordable system that can relatively easily be programmed to generate physiological waveforms. The system described here was designed to be used in an in-vitro set-up for vascular access hemodynamics research, and hence incorporates a gear pump that delivers a mean flow of 900 ml/min in a test flow loop, and a peak flow of 1106 ml/min. After a number of simple identification experiments to assess the dynamic behaviour of the system, a feed-forward control routine was implemented. The resulting system was shown to be able to produce the targeted representative waveform with less than 3.6% error. Finally, we outline how to further increase the accuracy of the system, and how to adapt it to specific user needs. Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.

  7. Controlling flow time delays in flexible manufacturing cells

    NARCIS (Netherlands)

    Slomp, J.; Caprihan, R.; Bokhorst, J. A. C.

    2009-01-01

    Flow time delays in Flexible Manufacturing Cells (FMCs) are caused by transport and clamping/reclamping activities. This paper shows how dynamic scheduling parameters may control the flow times of jobs and the available task windows for flow time delays.

  8. Wake flow control using a dynamically controlled wind turbine

    Science.gov (United States)

    Castillo, Ricardo; Wang, Yeqin; Pol, Suhas; Swift, Andy; Hussain, Fazle; Westergaard, Carsten; Texas Tech University Team

    2016-11-01

    A wind tunnel based "Hyper Accelerated Wind Farm Kinematic-Control Simulator" (HAWKS) is being built at Texas Tech University to emulate controlled wind turbine flow physics. The HAWKS model turbine has pitch, yaw and speed control which is operated in real model time, similar to that of an equivalent full scale turbine. Also, similar to that of a full scale wind turbine, the controls are developed in a Matlab Simulink environment. The current diagnostic system consists of power, rotor position, rotor speed measurements and PIV wake characterization with four cameras. The setup allows up to 7D downstream of the rotor to be mapped. The purpose of HAWKS is to simulate control strategies at turnaround times much faster than CFD and full scale testing. The fundamental building blocks of the simulator have been tested, and demonstrate wake steering for both static and dynamic turbine actuation. Parameters which have been studied are yaw, rotor speed and combinations hereof. The measured wake deflections for static yaw cases are in agreement with previously reported research implying general applicability of the HAWKS platform for the purpose of manipulating the wake. In this presentation the general results will be introduced followed by an analysis of the wake turbulence and coherent structures when comparing static and dynamic flow cases. The outcome of such studies could ultimately support effective wind farm wake flow control strategies. Texas Emerging Technology Fund (ETF).

  9. Flow-controlled magnetic particle manipulation

    Science.gov (United States)

    Grate, Jay W [West Richland, WA; Bruckner-Lea, Cynthia J [Richland, WA; Holman, David A [Las Vegas, NV

    2011-02-22

    Inventive methods and apparatus are useful for collecting magnetic materials in one or more magnetic fields and resuspending the particles into a dispersion medium, and optionally repeating collection/resuspension one or more times in the same or a different medium, by controlling the direction and rate of fluid flow through a fluid flow path. The methods provide for contacting derivatized particles with test samples and reagents, removal of excess reagent, washing of magnetic material, and resuspension for analysis, among other uses. The methods are applicable to a wide variety of chemical and biological materials that are susceptible to magnetic labeling, including, for example, cells, viruses, oligonucleotides, proteins, hormones, receptor-ligand complexes, environmental contaminants and the like.

  10. Flow Control Over Sharp-Edged Wings

    Science.gov (United States)

    2007-07-01

    Gad-el-Hak (2001) as the ability to actively or passively manipulate a flow field to effect a desired change. The challenge is to achieve that change...combinations. Been able to independently control both is a great challenge . These requirements may appear too stringent for the sharp- edged airfoils...06 0𔄁 08 09 lic Vlc Figure 22: Pressure distributions for Model B at a=13 °. Stations I (left); 2 (right) 1 , -2 1 F - [12 1 -6a -16 08 -08 06 -06

  11. Active Control of Jet Engine Inlet Flows

    National Research Council Canada - National Science Library

    Rediniotis, Othon; Bowersox, Rodney; Kirk, Aaron; Kumar, Abhinav; Tichenor, Nathan

    2007-01-01

    ...), flow visualization tests, particle image velocimetry (PIV), pressure probe and wall static tap experiments at various locations, the development and evolution of the secondary flow structures were observed...

  12. Effect of Flow Rate Controller on Liquid Steel Flow in Continuous Casting Mold using Numerical Modeling

    Science.gov (United States)

    Gursoy, Kadir Ali; Yavuz, Mehmet Metin

    2014-11-01

    In continuous casting operation of steel, the flow through tundish to the mold can be controlled by different flow rate control systems including stopper rod and slide-gate. Ladle changes in continuous casting machines result in liquid steel level changes in tundishes. During this transient event of production, the flow rate controller opening is increased to reduce the pressure drop across the opening which helps to keep the mass flow rate at the desired level for the reduced liquid steel level in tundish. In the present study, computational fluid dynamic (CFD) models are developed to investigate the effect of flow rate controller on mold flow structure, and particularly to understand the effect of flow controller opening on meniscus flow. First, a detailed validation of the CFD models is conducted using available experimental data and the performances of different turbulence models are compared. Then, the constant throughput casting operations for different flow rate controller openings are simulated to quantify the opening effect on meniscus region. The results indicate that the meniscus velocities are significantly affected by the flow rate controller and its opening level. The steady state operations, specified as constant throughput casting, do not provide the same mold flow if the controller opening is altered. Thus, for quality and castability purposes, adjusting the flow controller opening to obtain the fixed mold flow structure is proposed. Supported by Middle East Technical University (METU) BAP (Scientific Research Projects) Coordination.

  13. Access control mechanism of wireless gateway based on open flow

    Science.gov (United States)

    Peng, Rong; Ding, Lei

    2017-08-01

    In order to realize the access control of wireless gateway and improve the access control of wireless gateway devices, an access control mechanism of SDN architecture which is based on Open vSwitch is proposed. The mechanism utilizes the features of the controller--centralized control and programmable. Controller send access control flow table based on the business logic. Open vSwitch helps achieve a specific access control strategy based on the flow table.

  14. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...... in our understanding of cerebral blood flow control have important implications for the development of new therapeutic approaches....

  15. Sensor Development for Active Flow Control

    Science.gov (United States)

    Kahng, Seun K.; Gorton, Susan A.; Mau, Johnney C.; Soto, Hector L.; Hernandez, Corey D.

    2001-01-01

    Presented are the developmental efforts for MEMS sensors for a closed-loop active flow control in a low-speed wind tunnel evaluation. The MEMS sensors are designed in-house and fabricated out of house, and the shear sensors are a thermal type that are collocated with temperature and pressure sensors on a flexible polyimide sheet, which conforms to surfaces of a simple curvature. A total of 6 sensors are located within a 1.5 by 3 mm area as a cluster with each sensor being 300 pm square. The thickness of this sensor cluster is 75 pm. Outputs from the shear sensors have been compared with respect to those of the Preston tube for evaluation of the sensors on a flat plate. Pressure sensors are the absolute type and have recorded pressure measurements within 0.05 percent of the tunnel ESP pressure sensor readings. The sensors and signal conditioning electronics have been tested on both a flat plate and a ramp in Langley s 15-Inch Low-Turbulence Tunnel. The system configuration and control PC is configured with LabView, where calibration constants are stored for desired compensation and correction. The preliminary test results are presented within.

  16. Flow Control Device Evaluation for an Internal Flow with an Adverse Pressure Gradient

    Science.gov (United States)

    Jenkins, Luther N.; Gorton, Susan Althoff; Anders, Scott G.

    2002-01-01

    The effectiveness of several active and passive devices to control flow in an adverse pressure gradient with secondary flows present was evaluated in the 15 Inch Low Speed Tunnel at NASA Langley Research Center. In this study, passive micro vortex generators, micro bumps, and piezoelectric synthetic jets were evaluated for their flow control characteristics using surface static pressures, flow visualization, and 3D Stereo Digital Particle Image Velocimetry. Data also were acquired for synthetic jet actuators in a zero flow environment. It was found that the micro vortex generator is very effective in controlling the flow environment for an adverse pressure gradient, even in the presence of secondary vortical flow. The mechanism by which the control is effected is a re-energization of the boundary layer through flow mixing. The piezoelectric synthetic jet actuators must have sufficient velocity output to produce strong longitudinal vortices if they are to be effective for flow control. The output of these devices in a laboratory or zero flow environment will be different than the output in a flow environment. In this investigation, the output was higher in the flow environment, but the stroke cycle in the flow did not indicate a positive inflow into the synthetic jet.

  17. Glial and neuronal control of brain blood flow

    DEFF Research Database (Denmark)

    Attwell, David; Buchan, Alastair M; Charpak, Serge

    2010-01-01

    Blood flow in the brain is regulated by neurons and astrocytes. Knowledge of how these cells control blood flow is crucial for understanding how neural computation is powered, for interpreting functional imaging scans of brains, and for developing treatments for neurological disorders. It is now...... recognized that neurotransmitter-mediated signalling has a key role in regulating cerebral blood flow, that much of this control is mediated by astrocytes, that oxygen modulates blood flow regulation, and that blood flow may be controlled by capillaries as well as by arterioles. These conceptual shifts...

  18. Recent progress in flow control for practical flows results of the STADYWICO and IMESCON projects

    CERN Document Server

    Barakos, George; Luczak, Marcin

    2017-01-01

    This book explores the outcomes on flow control research activities carried out within the framework of two EU-funded projects focused on training-through-research of Marie Sklodowska-Curie doctoral students. The main goal of the projects described in this monograph is to assess the potential of the passive- and active-flow control methods for reduction of fuel consumption by a helicopter. The research scope encompasses the fields of structural dynamics, fluid flow dynamics, and actuators with control. Research featured in this volume demonstrates an experimental and numerical approach with a strong emphasis on the verification and validation of numerical models. The book is ideal for engineers, students, and researchers interested in the multidisciplinary field of flow control. Provides highly relevant and up-to-date information on the topic of flow control; Includes assessments of a wide range of flow-control technologies and application examples for fixed and rotary-wing configurations; Reinforces reader u...

  19. Improving Software Systems By Flow Control Analysis

    Directory of Open Access Journals (Sweden)

    Piotr Poznanski

    2012-01-01

    Full Text Available Using agile methods during the implementation of the system that meets mission critical requirements can be a real challenge. The change in the system built of dozens or even hundreds of specialized devices with embedded software requires the cooperation of a large group of engineers. This article presents a solution that supports parallel work of groups of system analysts and software developers. Deployment of formal rules to the requirements written in natural language enables using formal analysis of artifacts being a bridge between software and system requirements. Formalism and textual form of requirements allowed the automatic generation of message flow graph for the (sub system, called the “big-picture-model”. Flow diagram analysis helped to avoid a large number of defects whose repair cost in extreme cases could undermine the legitimacy of agile methods in projects of this scale. Retrospectively, a reduction of technical debt was observed. Continuous analysis of the “big picture model” improves the control of the quality parameters of the software architecture. The article also tries to explain why the commercial platform based on UML modeling language may not be sufficient in projects of this complexity.

  20. Review of hybrid laminar flow control systems

    Science.gov (United States)

    Krishnan, K. S. G.; Bertram, O.; Seibel, O.

    2017-08-01

    The aeronautic community always strived for fuel efficient aircraft and presently, the need for ecofriendly aircraft is even more, especially with the tremendous growth of air traffic and growing environmental concerns. Some of the important drivers for such interests include high fuel prices, less emissions requirements, need for more environment friendly aircraft to lessen the global warming effects. Hybrid laminar flow control (HLFC) technology is promising and offers possibility to achieve these goals. This technology was researched for decades for its application in transport aircraft, and it has achieved a new level of maturity towards integration and safety and maintenance aspects. This paper aims to give an overview of HLFC systems research and associated flight tests in the past years both in the US and in Europe. The review makes it possible to distinguish between the successful approaches and the less successful or outdated approaches in HLFC research. Furthermore, the technology status shall try to produce first estimations regarding the mass, power consumption and performance of HLFC systems as well as estimations regarding maintenance requirements and possible subsystem definitions.

  1. Electroosmotically controllable multi-flow microreactor

    NARCIS (Netherlands)

    Kohlheyer, D.; Besselink, G.A.J.; Lammertink, Rob G.H.; Schlautmann, Stefan; Unnikrishnan, S.; Schasfoort, Richardus B.M.

    2005-01-01

    An adjustable diffusion-based microfluidic reactor is presented here, which is based on electro-osmotic guiding of reagent samples. The device consists of a laminar flow chamber with two separate reagent inlets. The position and the width of the two sample streams in the flow chamber can be

  2. Flow Control for Supersonic Inlet Applications

    Science.gov (United States)

    2014-06-10

    1221-1233, May 2013 3. Loth, E., Titchener, N., Babinsky, H., Povinelli , L., “Canonical NSBLI Flows Relevant to External Compression Inlets”, AIAA J...Tennessee, Jan. 9-12, 2012 7. Loth, E.L., Titchener, N., Babinsky, H., Povinelli , L.A., “A Canonical Normal SBLI Flow Relevant to External

  3. Use of UPFC device controlled by fuzzy logic controllers for decoupled power flow control

    Directory of Open Access Journals (Sweden)

    Ivković Sanja

    2014-01-01

    Full Text Available This paper investigates the possibility of decoupled active and reactive power flow control in a power system using a UPFC device controlled by fuzzy logic controllers. A Brief theoretical review of the operation principles and applications of UPFC devices and design principles of the fuzzy logic controller used are given. A Matlab/Simulink model of the system with UPFC, the fuzzy controller setup, and graphs of the results are presented. Conclusions are drawn regarding the possibility of using this system for decoupled control of the power flow in power systems based on analysis of these graphs.

  4. Control of District Heating System with Flow-dependent Delays

    DEFF Research Database (Denmark)

    Bendtsen, Jan Dimon; Ledesma, Jorge Val; Kallesøe, Carsten Skovmose

    2017-01-01

    All flow systems are subject to transport delays, which are governed by the flow rates in the system. When the flow rates themselves are control inputs, the system becomes subject to input-dependent state delays, which poses significant theoretical problems. In an earlier paper, we proposed...

  5. The art and science of flow control - case studies using flow visualization methods

    Science.gov (United States)

    Alvi, F. S.; Cattafesta, L. N., III

    2010-04-01

    Active flow control (AFC) has been the focus of significant research in the last decade. This is mainly due to the potentially substantial benefits it affords. AFC applications range from the subsonic to the supersonic (and beyond) regime for both internal and external flows. These applications are wide and varied, such as controlling flow transition and separation over various external components of the aircraft to active management of separation and flow distortion in engine components and over turbine and compressor blades. High-speed AFC applications include control of flow oscillations in cavity flows, supersonic jet screech, impinging jets, and jet-noise control. In this paper we review some of our recent applications of AFC through a number of case studies that illustrate the typical benefits as well as limitations of present AFC methods. The case studies include subsonic and supersonic canonical flowfields such as separation control over airfoils, control of supersonic cavity flows and impinging jets. In addition, properties of zero-net mass-flux (ZNMF) actuators are also discussed as they represent one of the most widely studied actuators used for AFC. In keeping with the theme of this special issue, the flowfield properties and their response to actuation are examined through the use of various qualitative and quantitative flow visualization methods, such as smoke, shadowgraph, schlieren, planar-laser scattering, and Particle image velocimetry (PIV). The results presented here clearly illustrate the merits of using flow visualization to gain significant insight into the flow and its response to AFC.

  6. Thaw flow control for liquid heat transport systems

    Science.gov (United States)

    Kirpich, Aaron S.

    1989-01-01

    In a liquid metal heat transport system including a source of thaw heat for use in a space reactor power system, the thaw flow throttle or control comprises a fluid passage having forward and reverse flow sections and a partition having a plurality of bleed holes therein to enable fluid flow between the forward and reverse sections. The flow throttle is positioned in the system relatively far from the source of thaw heat.

  7. Microjet flow control in an ultra-compact serpentine inlet

    Directory of Open Access Journals (Sweden)

    Da Xingya

    2015-10-01

    Full Text Available Microjets are used to control the internal flow to improve the performance of an ultra-compact serpentine inlet. A highly offset serpentine inlet with length-to-diameter ratio of 2.5 is designed and static tests are conducted to analyze the internal flow characteristics in terms of pressure recovery, distortion and flow separation. Flow separation is encountered in the second S-turn, and two strong counter-rotating vortices are formed at the aerodynamic interface plane (AIP face which occupy a quarter of the outlet area and result in severe pressure loss and distortion. A flow control model employing a row of microjets in the second turn is designed based on the internal flow characteristics and simplified CFD simulations. Flow control tests are conducted to verify the control effectiveness and understand the characteristics as a function of inlet throat Mach number, injection mass flow ratio, jet Mach number and momentum coefficient. At all test Mach numbers, microjet flow control (MFC effectively improves the recovery and reduces the distortion intensity. Between inlet throat Mach number 0.2 and 0.5, the strong flow separation in the second S-turn is suppressed at an optimum jet flow ratio of less than 0.65%, resulting in a maximum improvement of 4% for pressure recovery coefficient and a maximum decrease of 75% for circumferential distortion intensity at cruise. However, in order to suppress the flow separation, the injection rate should retain in an effective range. When the injection rate is higher than this range, the flow is degraded and the distortion contour is changed from 90° circumferential distortion pattern to 180° circumferential distortion pattern. Detailed data analysis shows that this optimum flow ratio depends on inlet throat Mach number and the momentum coefficient affects the control effectiveness in a dual stepping manner.

  8. Boundary control of fluid flow through porous media

    DEFF Research Database (Denmark)

    Hasan, Agus; Foss, Bjarne; Sagatun, Svein Ivar

    2010-01-01

    The flow of fluids through porous media can be described by the Boussinesq’s equation with mixed boundary conditions; a Neumann’s boundary condition and a nonlinear boundary condition. The nonlinear boundary condition provides a means to control the fluid flow through porous media. In this paper,......, some stabilizing controllers are constructed for various cases using Lyapunov design.......The flow of fluids through porous media can be described by the Boussinesq’s equation with mixed boundary conditions; a Neumann’s boundary condition and a nonlinear boundary condition. The nonlinear boundary condition provides a means to control the fluid flow through porous media. In this paper...

  9. Plasma Control of Turbine Secondary Flows, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — We propose Phase I and II efforts that will focus on turbomachinery flow control. Specifically, the present work will investigate active control in a high speed...

  10. Information-flow-based Access Control for Virtualized Systems

    Directory of Open Access Journals (Sweden)

    Dmitriy Aleksandrovich Postoev

    2014-12-01

    Full Text Available The article is devoted to the method of information-flow-based access control, adopted for virtualized systems. General structure of access control system for virtual infrastructure is proposed.

  11. State Space Reduction of Linear Processes using Control Flow Reconstruction

    NARCIS (Netherlands)

    van de Pol, Jan Cornelis; Timmer, Mark

    2009-01-01

    We present a new method for fighting the state space explosion of process algebraic specifications, by performing static analysis on an intermediate format: linear process equations (LPEs). Our method consists of two steps: (1) we reconstruct the LPE's control flow, detecting control flow parameters

  12. State Space Reduction of Linear Processes Using Control Flow Reconstruction

    NARCIS (Netherlands)

    van de Pol, Jan Cornelis; Timmer, Mark; Liu, Zhiming; Ravn, Anders P.

    2009-01-01

    We present a new method for fighting the state space explosion of process algebraic specifications, by performing static analysis on an intermediate format: linear process equations (LPEs). Our method consists of two steps: (1) we reconstruct the LPE's control flow, detecting control flow parameters

  13. SPIV study of passive flow control on a WT airfoil

    DEFF Research Database (Denmark)

    Velte, Clara Marika; Hansen, Martin Otto Laver; Meyer, Knud Erik

    2010-01-01

    to free stream velocity U=15 m/s. The objective was to investigate the flow structures induced by and separation controlling behavior of vortex generators on the airfoil. The experimental results show strong separation of the uncontrolled flow whereas an intermittent behavior appears for the controlled...

  14. Power flow analysis for DC voltage droop controlled DC microgrids

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Dragicevic, Tomislav

    2014-01-01

    This paper proposes a new algorithm for power flow analysis in droop controlled DC microgrids. By considering the droop control in the power flow analysis for the DC microgrid, when compared with traditional methods, more accurate analysis results can be obtained. The algorithm verification is ca...

  15. Reactor core flow rate control system

    International Nuclear Information System (INIS)

    Sakuma, Hitoshi; Tanikawa, Naoshi; Takahashi, Toshiyuki; Miyakawa, Tetsuya.

    1996-01-01

    When an internal pump is started by a variable frequency power source device, if magnetic fields of an AC generator are introduced after the rated speed is reached, neutron flux high scram occurs by abrupt increase of a reactor core flow rate. Then, in the present invention, magnetic fields for the AC generator are introduced at a speed previously set at which the fluctuation range of the reactor core flow rate (neutron flux) by the start up of the internal pump is within an allowable value. Since increase of the speed of the internal pump upon its start up is suppressed to determine the change of the reactor core flow rate within an allowable range, increase of neutron fluxes is suppressed to enable stable start up. Then, since transition boiling of fuels caused by abrupt decrease of the reactor core flow rate upon occurrence of abnormality in an external electric power system is prevented, and the magnetic fields for the AC generator are introduced in such a manner to put the speed increase fluctuation range of the internal pump upon start up within an allowable value, neutron flux high scram is not caused to enable stable start-up. (N.H.)

  16. Modeling and control of compressor flow instabilities

    NARCIS (Netherlands)

    Willems, F.P.T.; Jager, de A.G.

    1999-01-01

    Compressors are widely used for the pressurization of fluids. Applications involve air compression for use in aircraft engines and pressurization and transportation of gas in the process and chemical industries. The article focuses on two commonly used types of continuous flow compressors: the axial

  17. ISS Payload Racks Automated Flow Control Calibration Method

    Science.gov (United States)

    Simmonds, Boris G.

    2003-01-01

    Payload Racks utilize MTL and/or LTL station water for cooling of payloads and avionics. Flow control range from valves of fully closed, to up to 300 Ibmhr. Instrument accuracies are as high as f 7.5 Ibm/hr for flow sensors and f 3 Ibm/hr for valve controller, for a total system accuracy of f 10.5 Ibm/hr. Improved methodology was developed, tested and proven that reduces accuracy of the commanded flows to less than f 1 Ibmhr. Uethodology could be packed in a "calibration kit" for on- orbit flow sensor checkout and recalibration, extending the rack operations before return to earth. -

  18. Measurement and control systems for an imaging electromagnetic flow metre.

    Science.gov (United States)

    Zhao, Y Y; Lucas, G; Leeungculsatien, T

    2014-03-01

    Electromagnetic flow metres based on the principles of Faraday's laws of induction have been used successfully in many industries. The conventional electromagnetic flow metre can measure the mean liquid velocity in axisymmetric single phase flows. However, in order to achieve velocity profile measurements in single phase flows with non-uniform velocity profiles, a novel imaging electromagnetic flow metre (IEF) has been developed which is described in this paper. The novel electromagnetic flow metre which is based on the 'weight value' theory to reconstruct velocity profiles is interfaced with a 'Microrobotics VM1' microcontroller as a stand-alone unit. The work undertaken in the paper demonstrates that an imaging electromagnetic flow metre for liquid velocity profile measurement is an instrument that is highly suited for control via a microcontroller. © 2013 ISA Published by ISA All rights reserved.

  19. Suboptimal control for drag reduction in turbulent pipe flow

    International Nuclear Information System (INIS)

    Choi, Jung Il; Sung, Hyung Jin; Xu, Chun Xiao

    2001-01-01

    A suboptimal control law in turbulent pipe flow is derived and tested. Two sensing variables ∂ρ/∂θ / w and ∂ν θ /∂r / w are applied with two actuations φ θ and φ γ . To test the suboptimal control law, direct numerical simulations of turbulent pipe flow at Re τ =150 are performed. When the control law is applied, a 13∼23% drag reduction is achieved. The most effective drag reduction is made at the pair of ∂υ θ /∂r / w and φ γ . An impenetrable virtual wall concept is useful for analyzing the near-wall suction and blowing. The virtual wall concept is useful for analyzing the near-wall behavior of the controlled flow. Comparison of the present suboptimal control with that of turbulent channel flow reveals that the curvature effect is insignificant

  20. Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

    Science.gov (United States)

    Cary, Robert E.

    2015-12-08

    Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

  1. Highly simplified lateral flow-based nucleic acid sample preparation and passive fluid flow control

    Energy Technology Data Exchange (ETDEWEB)

    Cary, Robert B.

    2018-04-17

    Highly simplified lateral flow chromatographic nucleic acid sample preparation methods, devices, and integrated systems are provided for the efficient concentration of trace samples and the removal of nucleic acid amplification inhibitors. Methods for capturing and reducing inhibitors of nucleic acid amplification reactions, such as humic acid, using polyvinylpyrrolidone treated elements of the lateral flow device are also provided. Further provided are passive fluid control methods and systems for use in lateral flow assays.

  2. Photothermally controlled Marangoni flow around a micro bubble

    International Nuclear Information System (INIS)

    Namura, Kyoko; Nakajima, Kaoru; Kimura, Kenji; Suzuki, Motofumi

    2015-01-01

    We have experimentally investigated the control of Marangoni flow around a micro bubble using photothermal conversion. Using a focused laser spot acting as a highly localized heat source on Au nanoparticles/dielectric/Ag mirror thin film enables us to create a micro bubble and to control the temperature gradient around the bubble at a micrometer scale. When we irradiate the laser next to the bubble, a strong main flow towards the bubble and two symmetric rotation flows on either side of it develop. The shape of this rotation flow shows a significant transformation depending on the relative position of the bubble and the laser spot. Using this controllable rotation flow, we have demonstrated sorting of the polystyrene spheres with diameters of 2 μm and 0.75 μm according to their size

  3. Photothermally controlled Marangoni flow around a micro bubble

    Science.gov (United States)

    Namura, Kyoko; Nakajima, Kaoru; Kimura, Kenji; Suzuki, Motofumi

    2015-01-01

    We have experimentally investigated the control of Marangoni flow around a micro bubble using photothermal conversion. Using a focused laser spot acting as a highly localized heat source on Au nanoparticles/dielectric/Ag mirror thin film enables us to create a micro bubble and to control the temperature gradient around the bubble at a micrometer scale. When we irradiate the laser next to the bubble, a strong main flow towards the bubble and two symmetric rotation flows on either side of it develop. The shape of this rotation flow shows a significant transformation depending on the relative position of the bubble and the laser spot. Using this controllable rotation flow, we have demonstrated sorting of the polystyrene spheres with diameters of 2 μm and 0.75 μm according to their size.

  4. International Conference on Instability and Control of Massively Separated Flows

    CERN Document Server

    Soria, Julio

    2015-01-01

    This book contains the outcome of the international meeting on instability, control and noise generated by massive flow separation that was organized at the Monash Center, in Prato, Italy, September 4-6, 2013. The meeting served as the final review of the EU-FP7 Instability and Control of Massively Separated Flows Marie Curie travel grant and was supported by the European Office of Aerospace Research and Development. Fifty leading specialists from twelve countries reviewed the progress made since the 50s of the last century and discussed modern analysis techniques, advanced experimental flow diagnostics, and recent developments in active flow control techniques from the incompressible to the hypersonic regime. Applications involving massive flow separation and associated instability and noise generation mechanisms of interest to the aeronautical, naval and automotive industries have been addressed from a theoretical, numerical or experimental point of view, making this book a unique source containing the stat...

  5. Control of flow geometry using electromagnetic body forcing

    International Nuclear Information System (INIS)

    Rossi, L.; Bocquet, S.; Ferrari, S.; Garcia de la Cruz, J.M.; Lardeau, S.

    2009-01-01

    This paper presents conceptual experiments and simulations aiming at controlling flow geometries. Such flow design is performed by driving electromagnetically a shallow layer of brine, the forcing being generated by a transverse electrical current and different combinations of permanent magnets placed underneath the brine supporting wall. It is shown how different basic flow characteristics can be obtained with a single pair of magnets, by varying the angle with the electrical current. These basic flows are proposed as potential building blocks for advanced and complex flows studies. Three typical flow structures are presented to illustrate these building blocks. The discussion is then extended to multi-scale geometry by using blocks of various sizes. The flow is analysed using complementary experiments and numerical simulations. A good agreement is found between the 3D simulations and the experiments for both velocity and acceleration fields, which allows a higher degree of confidence in designing and modelling such flows. As the control of the flow geometry is important for mixing, in particular at low Reynolds number, we also illustrate the different stirring properties of the electromagnetically forced flows by comparing visualisations of passive scalars. They reveal complementary mixing properties for each of the building blocks.

  6. Power flow control of intertied ac microgrids

    DEFF Research Database (Denmark)

    Nutkani, Inam Ullah; Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    Microgrids are small reliable grids formed by clustering distributed sources and loads together. They can, in principle, operate at different voltages and frequencies like 50, 60, 400 Hz or even dc. Tying them together or to the mains grid for energy sharing would therefore require the insertion...... of interlinking power converters. Active and reactive power flows of these converters should preferably be managed autonomously without demanding for fast communication links. A scheme that can fulfill the objectives is now proposed, which upon realised, will result in more robustly integrated microgrids...

  7. Automatic coolant flow control device for a nuclear reactor assembly

    Science.gov (United States)

    Hutter, Ernest

    1986-01-01

    A device which controls coolant flow through a nuclear reactor assembly comprises a baffle means at the exit end of said assembly having a plurality of orifices, and a bimetallic member in operative relation to the baffle means such that at increased temperatures said bimetallic member deforms to unblock some of said orifices and allow increased coolant flow therethrough.

  8. The Combination of Micro Diaphragm Pumps and Flow Sensors for Single Stroke Based Liquid Flow Control

    Directory of Open Access Journals (Sweden)

    Christoph Jenke

    2017-04-01

    Full Text Available With the combination of micropumps and flow sensors, highly accurate and secure closed-loop controlled micro dosing systems for liquids are possible. Implementing a single stroke based control mode with piezoelectrically driven micro diaphragm pumps can provide a solution for dosing of volumes down to nanoliters or variable average flow rates in the range of nL/min to μL/min. However, sensor technologies feature a yet undetermined accuracy for measuring highly pulsatile micropump flow. Two miniaturizable in-line sensor types providing electrical readout—differential pressure based flow sensors and thermal calorimetric flow sensors—are evaluated for their suitability of combining them with mircopumps. Single stroke based calibration of the sensors was carried out with a new method, comparing displacement volumes and sensor flow volumes. Limitations of accuracy and performance for single stroke based flow control are described. Results showed that besides particle robustness of sensors, controlling resistive and capacitive damping are key aspects for setting up reproducible and reliable liquid dosing systems. Depending on the required average flow or defined volume, dosing systems with an accuracy of better than 5% for the differential pressure based sensor and better than 6.5% for the thermal calorimeter were achieved.

  9. The Combination of Micro Diaphragm Pumps and Flow Sensors for Single Stroke Based Liquid Flow Control.

    Science.gov (United States)

    Jenke, Christoph; Pallejà Rubio, Jaume; Kibler, Sebastian; Häfner, Johannes; Richter, Martin; Kutter, Christoph

    2017-04-03

    With the combination of micropumps and flow sensors, highly accurate and secure closed-loop controlled micro dosing systems for liquids are possible. Implementing a single stroke based control mode with piezoelectrically driven micro diaphragm pumps can provide a solution for dosing of volumes down to nanoliters or variable average flow rates in the range of nL/min to μL/min. However, sensor technologies feature a yet undetermined accuracy for measuring highly pulsatile micropump flow. Two miniaturizable in-line sensor types providing electrical readout-differential pressure based flow sensors and thermal calorimetric flow sensors-are evaluated for their suitability of combining them with mircopumps. Single stroke based calibration of the sensors was carried out with a new method, comparing displacement volumes and sensor flow volumes. Limitations of accuracy and performance for single stroke based flow control are described. Results showed that besides particle robustness of sensors, controlling resistive and capacitive damping are key aspects for setting up reproducible and reliable liquid dosing systems. Depending on the required average flow or defined volume, dosing systems with an accuracy of better than 5% for the differential pressure based sensor and better than 6.5% for the thermal calorimeter were achieved.

  10. On load flow control in electric power systems

    Energy Technology Data Exchange (ETDEWEB)

    Herbig, Arnim

    2000-01-01

    This dissertation deals with the control of active power flow, or load flow in electric power systems. During the last few years, interest in the possibilities to control the active power flows in transmission systems has increased significantly. There is a number of reasons for this, coming both from the application side - that is, from power system operations - and from the technological side. where advances in power electronics and related technologies have made new system components available. Load flow control is by nature a multi-input multi-output problem, since any change of load flow in one line will be complemented by changes in other lines. Strong cross-coupling between controllable components is to be expected, and the possibility of adverse interactions between these components cannot be rejected straightaway. Interactions with dynamic phenomena in the power system are also a source of concern. Three controllable components are investigated in this thesis, namely the controlled series capacitor (CSC), the phase angle regulator (PAR), and the unified power flow controller (UPFC). Properties and characteristics of these devices axe investigated and discussed. A simple control strategy is proposed. This strategy is then analyzed extensively. Mathematical methods and physical knowledge about the pertinent phenomena are combined, and it is shown that this control strategy can be used for a fairly general class of devices. Computer simulations of the controlled system provide insight into the system behavior in a system of reasonable size. The robustness and stability of the control system are discussed as are its limits. Further, the behavior of the control strategy in a system where the modeling allows for dynamic phenomena are investigated with computer simulations. It is discussed under which circumstances the control action has beneficial or detrimental effect on the system dynamics. Finally, a graphical approach for analyzing the effect of controllers

  11. Usefulness of DC power flow for active power flow analysis with flow controlling devices

    NARCIS (Netherlands)

    Van Hertem, D.; Verboomen, J.; Purchala, K.; Belmans, R.; Kling, W.L.

    2006-01-01

    DC power flow is a commonly used tool for contingency analysis. Recently, due to its simplicity and robustness, it also becomes increasingly used for the real-time dispatch and techno-economic analysis of power systems. It is a simplification of a full power flow looking only at active power.

  12. Pick'n'Fix: Capturing Control Flow in Modular Compilers

    DEFF Research Database (Denmark)

    Day, Laurence E.; Bahr, Patrick

    2014-01-01

    structures, in particular cyclic ones, we employ Oliveira and Cook's purely functional representation of graphs. Moreover, to separate control flow features semantically from other language features, we represent source languages using Johann and Ghani's encoding of generalised algebraic datatypes...

  13. RETROFITTING CONTROL FACILITIES FOR WET-WEATHER FLOW TREATMENT

    Science.gov (United States)

    Available technologies were evaluated to demonstrate the technical feasibility and cost effectiveness of retrofitting existing facilities to handle wet-weather flow. Cost/benefit relationships were also compared to construction of new conventional control and treatment facilities...

  14. Orifice design for the control of coupled region flow

    International Nuclear Information System (INIS)

    Atherton, R.; Spadaro, P.R.; Brummerhop, F.G.

    1975-01-01

    A fluid system arrangement for nuclear reactors is described comprising a triplate orifice apparatus which simultaneously controls core flow distribution, flow rate ratio between hydraulically coupled regions of the blanket and radial static pressure gradients entering and leaving the blanket fuel region. The design of the apparatus is based on the parameters of the diameter of the orifice holes, the friction factor, and expansion, contraction and turning pressure loss coefficients of the geometry of each orifice region. These above parameters are properly matched to provide the desired pressure drop, flow split and negligible cross flow at the interface of standard and power-flattened open lattice blanket regions. (U.S.)

  15. Reactive Flow Control of Delta Wing Vortex (Postprint)

    Science.gov (United States)

    2006-08-01

    wing aircraft. A substantial amount of research has been dedicated to the control of aerodynamic flows using both passive and active control mechanisms...Passive vortex control devices such as vortex generators and winglets attach to the wing and require no energy input. Passive vortex control...leading edges is also effective for changing the aerodynamic characteristics of delta wings [2] [3]. Gutmark and Guillot [5] proposed controlling

  16. Flow-Control Unit For Nitrogen And Hydrogen Gases

    Science.gov (United States)

    Chang, B. J.; Novak, D. W.

    1990-01-01

    Gas-flow-control unit installed and removed as one piece replaces system that included nine separately serviced components. Unit controls and monitors flows of nitrogen and hydrogen gases. Designed for connection via fluid-interface manifold plate, reducing number of mechanical fluid-interface connections from 18 to 1. Unit provides increasing reliability, safety, and ease of maintenance, and for reducing weight, volume, and power consumption.

  17. Turbulent Flow Modification With Thermoacoustic Waves for Separation Control

    Science.gov (United States)

    2017-08-24

    respectively. At the outlet, the time-average flow is set to be the target state of the sponge zone. In this section, the effects of momentum thickness...Turbulent Flow Modification With Thermoacoustic Waves For Separation Control The views, opinions and/or findings contained in this report are those...currently valid OMB control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. Florida State University Sponsored Research Administration 874

  18. Exhaust bypass flow control for exhaust heat recovery

    Science.gov (United States)

    Reynolds, Michael G.

    2015-09-22

    An exhaust system for an engine comprises an exhaust heat recovery apparatus configured to receive exhaust gas from the engine and comprises a first flow passage in fluid communication with the exhaust gas and a second flow passage in fluid communication with the exhaust gas. A heat exchanger/energy recovery unit is disposed in the second flow passage and has a working fluid circulating therethrough for exchange of heat from the exhaust gas to the working fluid. A control valve is disposed downstream of the first and the second flow passages in a low temperature region of the exhaust heat recovery apparatus to direct exhaust gas through the first flow passage or the second flow passage.

  19. Bluff Body Flow Control Using Dielectric Barrier Discharge Plasma Actuators

    Science.gov (United States)

    Thomas, Flint; Kozlov, Alexey

    2008-11-01

    The results of an experimental investigation involving the use of dielectric barrier discharge plasma actuators to control bluff body flow is presented. The motivation for the work is plasma landing gear noise control for commercial transport aircraft. For these flow control experiments, the cylinder in cross-flow is chosen for study since it represents a generic flow geometry that is similar in all essential aspects to a landing gear strut. The current work is aimed both at extending the plasma flow control concept to Reynolds numbers typical of landing approach and take-off and on the development of optimum plasma actuation strategies. The cylinder wake flow with and without actuation are documented in detail using particle image velocimetry (PIV) and constant temperature hot-wire anemometry. The experiments are performed over a Reynolds number range extending to ReD=10^5. Using either steady or unsteady plasma actuation, it is demonstrated that even at the highest Reynolds number Karman shedding is totally eliminated and turbulence levels in the wake decrease by more than 50%. By minimizing the unsteady flow separation from the cylinder and associated large-scale wake vorticity, the radiated aerodynamic noise is also reduced.

  20. A Numerical Proof of Concept for Thermal Flow Control

    Directory of Open Access Journals (Sweden)

    V. Dragan

    2017-02-01

    Full Text Available In this paper computational fluid dynamics is used to provide a proof of concept for controlled flow separation using thermal wall interactions with the velocity boundary layer. A 3D case study is presented, using a transition modeling Shear Stress Transport turbulence model. The highly loaded single slot flap airfoil was chosen to be representative for a light aircraft and the flow conditions were modeled after a typical landing speed. In the baseline case, adiabatic walls were considered while in the separation control case, the top surface of the flaps was heated to 500 K. This heating lead to flow separation on the flaps and a significant alteration of the flow pattern across all the elements of the wing. The findings indicate that this control method has potential, with implications in both aeronautical as well as sports and civil engineering applications.

  1. Flow and Noise Control: Review and Assessment of Future Directions

    Science.gov (United States)

    Thomas, Russell H.; Choudhari, Meelan M.; Joslin, Ronald D.

    2002-01-01

    Technologies for developing radically new aerovehicles that would combine quantum leaps in cost, safety, and performance benefits with environmental friendliness have appeared on the horizon. This report provides both an assessment of the current state-of-the-art in flow and noise control and a vision for the potential gains to be made, in terms of performance benefit for civil and military aircraft and a unique potential for noise reduction, via future advances in flow and noise technologies. This report outlines specific areas of research that will enable the breakthroughs necessary to bring this vision to reality. Recent developments in many topics within flow and noise control are reviewed. The flow control overview provides succinct summaries of various approaches for drag reduction and improved maneuvering. Both exterior and interior noise problems are examined, including dominant noise sources, physics of noise generation and propagation, and both established and proposed concepts for noise reduction. Synergy between flow and noise control is a focus and, more broadly, the need to pursue research in a more concurrent approach involving multiple disciplines. Also discussed are emerging technologies such as nanotechnology that may have a significant impact on the progress of flow and noise control.

  2. Active Flow Control and Global Stability Analysis of Separated Flow Over a NACA 0012 Airfoil

    Science.gov (United States)

    Munday, Phillip M.

    The objective of this computational study is to examine and quantify the influence of fundamental flow control inputs in suppressing flow separation over a canonical airfoil. Most flow control studies to this date have relied on the development of actuator technology, and described the control input based on specific actuators. Taking advantage of a computational framework, we generalize the inputs to fundamental perturbations without restricting inputs to a particular actuator. Utilizing this viewpoint, generalized control inputs aim to aid in the quantification and support the design of separation control techniques. This study in particular independently introduces wall-normal momentum and angular momentum to the separated flow using swirling jets through model boundary conditions. The response of the flow field and the surface vorticity fluxes to various combinations of actuation inputs are examined in detail. By closely studying different variables, the influence of the wall-normal and angular momentum injections on separated flow is identified. As an example, open-loop control of fully separated, incompressible flow over a NACA 0012 airfoil at alpha = 6° and 9° with Re = 23,000 is examined with large-eddy simulations. For the shallow angle of attack alpha = 6°, the small recirculation region is primarily affected by wall-normal momentum injection. For a larger separation region at alpha = 9°, it is observed that the addition of angular momentum input to wall-normal momentum injection enhances the suppression of flow separation. Reducing the size of the separated flow region significantly impacts the forces, and in particular reduces drag and increases lift on the airfoil. It was found that the influence of flow control on the small recirculation region (alpha = 6°) can be sufficiently quantified with the traditional coefficient of momentum. At alpha = 9°, the effects of wall-normal and angular momentum inputs are captured by modifying the standard

  3. Global nuclear material flow/control model

    International Nuclear Information System (INIS)

    Dreicer, J.S.; Rutherford, D.S.; Fasel, P.K.; Riese, J.M.

    1997-01-01

    This is the final report of a two-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The nuclear danger can be reduced by a system for global management, protection, control, and accounting as part of an international regime for nuclear materials. The development of an international fissile material management and control regime requires conceptual research supported by an analytical and modeling tool which treats the nuclear fuel cycle as a complete system. The prototype model developed visually represents the fundamental data, information, and capabilities related to the nuclear fuel cycle in a framework supportive of national or an international perspective. This includes an assessment of the global distribution of military and civilian fissile material inventories, a representation of the proliferation pertinent physical processes, facility specific geographic identification, and the capability to estimate resource requirements for the management and control of nuclear material. The model establishes the foundation for evaluating the global production, disposition, and safeguards and security requirements for fissile nuclear material and supports the development of other pertinent algorithmic capabilities necessary to undertake further global nuclear material related studies

  4. Control of a Quadcopter Aerial Robot Using Optic Flow Sensing

    Science.gov (United States)

    Hurd, Michael Brandon

    This thesis focuses on the motion control of a custom-built quadcopter aerial robot using optic flow sensing. Optic flow sensing is a vision-based approach that can provide a robot the ability to fly in global positioning system (GPS) denied environments, such as indoor environments. In this work, optic flow sensors are used to stabilize the motion of quadcopter robot, where an optic flow algorithm is applied to provide odometry measurements to the quadcopter's central processing unit to monitor the flight heading. The optic-flow sensor and algorithm are capable of gathering and processing the images at 250 frames/sec, and the sensor package weighs 2.5 g and has a footprint of 6 cm2 in area. The odometry value from the optic flow sensor is then used a feedback information in a simple proportional-integral-derivative (PID) controller on the quadcopter. Experimental results are presented to demonstrate the effectiveness of using optic flow for controlling the motion of the quadcopter aerial robot. The technique presented herein can be applied to different types of aerial robotic systems or unmanned aerial vehicles (UAVs), as well as unmanned ground vehicles (UGV).

  5. Synthetic perspective optical flow: Influence on pilot control tasks

    Science.gov (United States)

    Bennett, C. Thomas; Johnson, Walter W.; Perrone, John A.; Phatak, Anil V.

    1989-01-01

    One approach used to better understand the impact of visual flow on control tasks has been to use synthetic perspective flow patterns. Such patterns are the result of apparent motion across a grid or random dot display. Unfortunately, the optical flow so generated is based on a subset of the flow information that exists in the real world. The danger is that the resulting optical motions may not generate the visual flow patterns useful for actual flight control. Researchers conducted a series of studies directed at understanding the characteristics of synthetic perspective flow that support various pilot tasks. In the first of these, they examined the control of altitude over various perspective grid textures (Johnson et al., 1987). Another set of studies was directed at studying the head tracking of targets moving in a 3-D coordinate system. These studies, parametric in nature, utilized both impoverished and complex virtual worlds represented by simple perspective grids at one extreme, and computer-generated terrain at the other. These studies are part of an applied visual research program directed at understanding the design principles required for the development of instruments displaying spatial orientation information. The experiments also highlight the need for modeling the impact of spatial displays on pilot control tasks.

  6. A note on supersonic flow control with nanosecond plasma actuator

    Science.gov (United States)

    Zheng, J. G.; Cui, Y. D.; Li, J.; Khoo, B. C.

    2018-04-01

    A concept study on supersonic flow control using nanosecond pulsed plasma actuator is conducted by means of numerical simulation. The nanosecond plasma discharge is characterized by the generation of a micro-shock wave in ambient air and a residual heat in the discharge volume arising from the rapid heating of near-surface gas by the quick discharge. The residual heat has been found to be essential for the flow separation control over aerodynamic bodies like airfoil and backward-facing step. In this study, novel experiment is designed to utilize the other flow feature from discharge, i.e., instant shock wave, to control supersonic flow through shock-shock interaction. Both bow shock in front of a blunt body and attached shock anchored at the tip of supersonic projectile are manipulated via the discharged-induced shock wave in an appropriate manner. It is observed that drag on the blunt body is reduced appreciably. Meanwhile, a lateral force on sharp-edged projectile is produced, which can steer the body and give it an effective angle of attack. This opens a promising possibility for extending the applicability of this flow control technique in supersonic flow regime.

  7. Multilevel flow modelling of process plant for diagnosis and control

    International Nuclear Information System (INIS)

    Lind, M.

    1982-08-01

    The paper describes the multilevel flow modelling methodology which can be used to construct functional models of energy and material processing systems. The models describe mass and energy flow topology on different levels of abstraction and represent the hierarchical functional structure of complex systems. A model of a nuclear power plant (PWR) is presented in the paper for illustration. Due to the consistency of the method, multilevel flow models provide specifications of plant goals and functions and may be used as a basis for design of computer-based support systems for the plant operator. Plant control requirements can be derived from the models and due to independence of the actual controller implementation the method may be used as basic for design of control strategies and for the allocation of control tasks to the computer and the plant operator. (author)

  8. Multilevel Flow Modelling of Process Plant for Diagnosis and Control

    DEFF Research Database (Denmark)

    Lind, Morten

    1982-01-01

    The paper describes the multilevel flow modelling methodology which can be used to construct functional models of energy and material processing systems. The models describe mass and energy flow topology on different levels of abstraction and represent the hierarchical functional structure...... of complex systems. A model of a nuclear power plant (PWR) is presented in the paper for illustration. Due to the consistency of the method, multilevel flow models provide specifications of plant goals and functions and may be used as a basis for design of computer-based support systems for the plant...... operator. Plant control requirements can be derived from the models and due to independence of the actual controller implementation the method may be used as a basis for design of control strategies and for the allocation of control tasks to the computer and the plant operator....

  9. Liquid metal flow control by DC electromagnetic pumps

    International Nuclear Information System (INIS)

    Borges, Eduardo Madeira; Braz Filho, Francisco Antonio; Guimaraes, Lamartine Nogueira Frutuoso

    2006-01-01

    The cooling system of high-density thermal power requires fluids of high thermal conductivity, such as liquid metals. Electromagnetic pumps can be used to liquid metal fluid flow control in cooling circuits. The operation of electromagnetic pumps used to flow control is based on Lorentz force. This force can be achieved by magnetic field and electric current interaction, controlled by external independent power supplies. This work presents the electromagnetic pump operational principles, the IEAv development scheme and the BEMC-1 simulation code. The theoretical results of BEMC-1 simulation are compared to electromagnetic pump operation experimental data, validating the BEMC-1 code. This code is used to evaluate the DC electromagnetic pump performance applied to Mercury flow control and others liquid metal such as Sodium, Lead and Bismuth, used in nuclear fast reactors. (author)

  10. Predictive Flow Control to Minimize Convective Time Delays

    Science.gov (United States)

    2013-08-19

    external flows around air vehicles or ground based systems such as bridges and buildings, internal flows in pipes and propulsion systems, acoustical...3437, 1977. [4] Bridges , D. H., "The Asymmetric Vortex Wake Problem - Asking the Right Question," A/AA Paper 2006-3553, 2006. [5) Deng, X. Y., Tian, W...Aircraft, Vol. 42, No. 2, 2003, pp. 42~23. [8] Darden, L. and Komerath, N., "Forebody Vortex Control at High Incidence using a Moveable Nose Stagnation

  11. Steady State Stokes Flow Interpolation for Fluid Control

    DEFF Research Database (Denmark)

    Bhatacharya, Haimasree; Nielsen, Michael Bang; Bridson, Robert

    2012-01-01

    — suffer from a common problem. They fail to capture the rotational components of the velocity field, although extrapolation in the normal direction does consider the tangential component. We address this problem by casting the interpolation as a steady state Stokes flow. This type of flow captures......Fluid control methods often require surface velocities interpolated throughout the interior of a shape to use the velocity as a feedback force or as a boundary condition. Prior methods for interpolation in computer graphics — velocity extrapolation in the normal direction and potential flow...

  12. Inlet Flow Control and Prediction Technologies for Embedded Propulsion Systems

    Science.gov (United States)

    McMillan, Michelle L.; Mackie, Scott A.; Gissen, Abe; Vukasinovic, Bojan; Lakebrink, Matthew T.; Glezer, Ari; Mani, Mori; Mace, James L.

    2011-01-01

    Fail-safe, hybrid, flow control (HFC) is a promising technology for meeting high-speed cruise efficiency, low-noise signature, and reduced fuel-burn goals for future, Hybrid-Wing-Body (HWB) aircraft with embedded engines. This report details the development of HFC technology that enables improved inlet performance in HWB vehicles with highly integrated inlets and embedded engines without adversely affecting vehicle performance. In addition, new test techniques for evaluating Boundary-Layer-Ingesting (BLI)-inlet flow-control technologies developed and demonstrated through this program are documented, including the ability to generate a BLI-like inlet-entrance flow in a direct-connect, wind-tunnel facility, as well as, the use of D-optimal, statistically designed experiments to optimize test efficiency and enable interpretation of results. Validated improvements in numerical analysis tools and methods accomplished through this program are also documented, including Reynolds-Averaged Navier-Stokes CFD simulations of steady-state flow physics for baseline, BLI-inlet diffuser flow, as well as, that created by flow-control devices. Finally, numerical methods were employed in a ground-breaking attempt to directly simulate dynamic distortion. The advances in inlet technologies and prediction tools will help to meet and exceed "N+2" project goals for future HWB aircraft.

  13. Temperature-gated thermal rectifier for active heat flow control.

    Science.gov (United States)

    Zhu, Jia; Hippalgaonkar, Kedar; Shen, Sheng; Wang, Kevin; Abate, Yohannes; Lee, Sangwook; Wu, Junqiao; Yin, Xiaobo; Majumdar, Arun; Zhang, Xiang

    2014-08-13

    Active heat flow control is essential for broad applications of heating, cooling, and energy conversion. Like electronic devices developed for the control of electric power, it is very desirable to develop advanced all-thermal solid-state devices that actively control heat flow without consuming other forms of energy. Here we demonstrate temperature-gated thermal rectification using vanadium dioxide beams in which the environmental temperature actively modulates asymmetric heat flow. In this three terminal device, there are two switchable states, which can be regulated by global heating. In the "Rectifier" state, we observe up to 28% thermal rectification. In the "Resistor" state, the thermal rectification is significantly suppressed (Rectifier state. This temperature-gated rectifier can have substantial implications ranging from autonomous thermal management of heating and cooling systems to efficient thermal energy conversion and storage.

  14. Application of Shark Skin Flow Control Techniques to Airflow

    Science.gov (United States)

    Morris, Jackson Alexander

    Due to millions of years of evolution, sharks have evolved to become quick and efficient ocean apex predators. Shark skin is made up of millions of microscopic scales, or denticles, that are approximately 0.2 mm in size. Scales located on the shark's body where separation control is paramount (such as behind the gills or the trailing edge of the pectoral fin) are capable of bristling. These scales are hypothesized to act as a flow control mechanism capable of being passively actuated by reversed flow. It is believed that shark scales are strategically sized to interact with the lower 5% of a boundary layer, where reversed flow occurs at the onset of boundary layer separation. Previous research has shown shark skin to be capable of controlling separation in water. This thesis aims to investigate the same passive flow control techniques in air. To investigate this phenomenon, several sets of microflaps were designed and manufactured with a 3D printer. The microflaps were designed in both 2D (rectangular) and 3D (mirroring shark scale geometry) variants. These microflaps were placed in a low-speed wind tunnel in the lower 5% of the boundary layer. Solid fences and a flat plate diffuser with suction were placed in the tunnel to create different separated flow regions. A hot film probe was used to measure velocity magnitude in the streamwise plane of the separated regions. The results showed that low-speed airflow is capable of bristling objects in the boundary layer. When placed in a region of reverse flow, the microflaps were passively actuated. Microflaps fluctuated between bristled and flat states in reverse flow regions located close to the reattachment zone.

  15. A Calculus for Control Flow Analysis of Security Protocols

    DEFF Research Database (Denmark)

    Buchholtz, Mikael; Nielson, Hanne Riis; Nielson, Flemming

    2004-01-01

    The design of a process calculus for anaysing security protocols is governed by three factors: how to express the security protocol in a precise and faithful manner, how to accommodate the variety of attack scenarios, and how to utilise the strengths (and limit the weaknesses) of the underlying...... analysis methodology. We pursue an analysis methodology based on control flow analysis in flow logic style and we have previously shown its ability to analyse a variety of security protocols. This paper develops a calculus, LysaNS that allows for much greater control and clarity in the description...

  16. Objective function choice for control of a thermocapillary flow using an adjoint-based control strategy

    International Nuclear Information System (INIS)

    Muldoon, Frank H.; Kuhlmann, Hendrik C.

    2015-01-01

    Highlights: • Suppression of oscillations in a thermocapillary flow is addressed by optimization. • The gradient of the objective function is obtained by solving the adjoint equations. • The issue of choosing an objective function is investigated. - Abstract: The problem of suppressing flow oscillations in a thermocapillary flow is addressed using a gradient-based control strategy. The physical problem addressed is the “open boat” process of crystal growth, the flow in which is driven by thermocapillary and buoyancy effects. The problem is modeled by the two-dimensional unsteady incompressible Navier–Stokes and energy equations under the Boussinesq approximation. The goal of the control is to suppress flow oscillations which arise when the driving forces are such that the flow becomes unsteady. The control is a spatially and temporally varying temperature gradient boundary condition at the free surface. The control which minimizes the flow oscillations is found using a conjugate gradient method, where the gradient of the objective function with respect to the control variables is obtained from solving a set of adjoint equations. The issue of choosing an objective function that can be both optimized in a computationally efficient manner and optimization of which provides control that damps the flow oscillations is investigated. Almost complete suppression of the flow oscillations is obtained for certain choices of the objective function.

  17. Topographic control of oceanic flows in deep passages and straits

    Science.gov (United States)

    Whitehead, J. A.

    1998-08-01

    Saddle points between neighboring deep ocean basins are the sites of unidirectional flow from one basin to the next, depending on the source of bottom water. Flow in these sites appears to be topographically controlled so the interface between the bottom water and the water above adjusts itself to permit bottom water flow from the basin that contains a source of bottom water into the next. Examples in the Atlantic include flow in the Romanche Fracture Zone, the Vema Channel, the Ceara Abyssal Plain, the Anegada-Jungfern passage, and the Discovery Gap, but there are many more. Theoretical predictions of volume flux using a method that requires only conductivity-temperature-depth data archives and detailed knowledge of bathymetry near the saddle point are compared with volume flux estimates using current meters and/or geostrophic estimates for seven cases. The ratio of prediction to volume flux estimate ranges from 1.0 to 2.7. Some ocean straits that separate adjacent seas are also found to critically control bidirectional flows between basins. Theory of the influence of rotation on such critical flows is reviewed. Predictions of volume flux in eight cases are compared with ocean estimates of volume flux from traditional methods.

  18. Structural integrated sensor and actuator systems for active flow control

    Science.gov (United States)

    Behr, Christian; Schwerter, Martin; Leester-Schädel, Monika; Wierach, Peter; Dietzel, Andreas; Sinapius, Michael

    2016-04-01

    An adaptive flow separation control system is designed and implemented as an essential part of a novel high-lift device for future aircraft. The system consists of MEMS pressure sensors to determine the flow conditions and adaptive lips to regulate the mass flow and the velocity of a wall near stream over the internally blown Coanda flap. By the oscillating lip the mass flow in the blowing slot changes dynamically, consequently the momentum exchange of the boundary layer over a high lift flap required mass flow can be reduced. These new compact and highly integrated systems provide a real-time monitoring and manipulation of the flow conditions. In this context the integration of pressure sensors into flow sensing airfoils of composite material is investigated. Mechanical and electrical properties of the integrated sensors are investigated under mechanical loads during tensile tests. The sensors contain a reference pressure chamber isolated to the ambient by a deformable membrane with integrated piezoresistors connected as a Wheatstone bridge, which outputs voltage signals depending on the ambient pressure. The composite material in which the sensors are embedded consists of 22 individual layers of unidirectional glass fiber reinforced plastic (GFRP) prepreg. The results of the experiments are used for adapting the design of the sensors and the layout of the laminate to ensure an optimized flux of force in highly loaded structures primarily for future aeronautical applications. It can be shown that the pressure sensor withstands the embedding process into fiber composites with full functional capability and predictable behavior under stress.

  19. Flow Characteristics of Ground Vehicle Wake and Its Response to Flow Control

    Science.gov (United States)

    Sellappan, Prabu; McNally, Jonathan; Alvi, Farrukh

    2017-11-01

    Air pollution, fuel shortages, and cost savings are some of the many incentives for improving the aerodynamics of vehicles. Reducing wake-induced aerodynamic drag, which is dependent on flow topology, on modern passenger vehicles is important for improving fuel consumption rates which directly affect the environment. In this research, an active flow control technique is applied on a generic ground vehicle, a 25°Ahmed model, to investigate its effect on the flow topology in the near-wake. The flow field of this canonical bluff body is extremely rich, with complex and unsteady flow features such as trailing wake vortices and c-pillar vortices. The spatio-temporal response of these flow features to the application of steady microjet actuators is investigated. The responses are characterized independently through time-resolved and volumetric velocity field measurements. The accuracy and cost of volumetric measurements in this complex flow field through Stereoscopic- and Tomographic- Particle Image Velocimetry (PIV) will also be commented upon. National Science Foundation PIRE Program.

  20. Verification of the karst flow model under laboratory controlled conditions

    Science.gov (United States)

    Gotovac, Hrvoje; Andric, Ivo; Malenica, Luka; Srzic, Veljko

    2016-04-01

    Karst aquifers are very important groundwater resources around the world as well as in coastal part of Croatia. They consist of extremely complex structure defining by slow and laminar porous medium and small fissures and usually fast turbulent conduits/karst channels. Except simple lumped hydrological models that ignore high karst heterogeneity, full hydraulic (distributive) models have been developed exclusively by conventional finite element and finite volume elements considering complete karst heterogeneity structure that improves our understanding of complex processes in karst. Groundwater flow modeling in complex karst aquifers are faced by many difficulties such as a lack of heterogeneity knowledge (especially conduits), resolution of different spatial/temporal scales, connectivity between matrix and conduits, setting of appropriate boundary conditions and many others. Particular problem of karst flow modeling is verification of distributive models under real aquifer conditions due to lack of above-mentioned information. Therefore, we will show here possibility to verify karst flow models under the laboratory controlled conditions. Special 3-D karst flow model (5.6*2.6*2 m) consists of concrete construction, rainfall platform, 74 piezometers, 2 reservoirs and other supply equipment. Model is filled by fine sand (3-D porous matrix) and drainage plastic pipes (1-D conduits). This model enables knowledge of full heterogeneity structure including position of different sand layers as well as conduits location and geometry. Moreover, we know geometry of conduits perforation that enable analysis of interaction between matrix and conduits. In addition, pressure and precipitation distribution and discharge flow rates from both phases can be measured very accurately. These possibilities are not present in real sites what this model makes much more useful for karst flow modeling. Many experiments were performed under different controlled conditions such as different

  1. Implementation of Logic Flow in Planning and Production Control

    Directory of Open Access Journals (Sweden)

    Ulewicz Robert

    2016-03-01

    Full Text Available The article presents the results of analysis, the use of continuous flow of logic at the stage of production planning and control of the company producing furniture. The concept of continuous flow tends to regulate the flow of materials in a manner that provides the shortest flow path without unnecessary activities (Muda is a Japanese word meaning waste, a constant takt and defined throughput at constant resource requirements for the so-called transfer of material through the whole process. In the study Glenday’d sieve method was used to identify the correct area, which requires the value stream mapping, and areas called excessive complexity, which do not provide added value. The use of Glenday’s sieve method made it possible to identify areas in which it must be improve production capacity.

  2. Controlled synthesis of poly(3-hexylthiophene in continuous flow

    Directory of Open Access Journals (Sweden)

    Helga Seyler

    2013-07-01

    Full Text Available There is an increasing demand for organic semiconducting materials with the emergence of organic electronic devices. In particular, large-area devices such as organic thin-film photovoltaics will require significant quantities of materials for device optimization, lifetime testing and commercialization. Sourcing large quantities of materials required for the optimization of large area devices is costly and often impossible to achieve. Continuous-flow synthesis enables straight-forward scale-up of materials compared to conventional batch reactions. In this study, poly(3-hexylthiophene, P3HT, was synthesized in a bench-top continuous-flow reactor. Precise control of the molecular weight was demonstrated for the first time in flow for conjugated polymers by accurate addition of catalyst to the monomer solution. The P3HT samples synthesized in flow showed comparable performance to commercial P3HT samples in bulk heterojunction solar cell devices.

  3. Field-effect Flow Control in Polymer Microchannel Networks

    Science.gov (United States)

    Sniadecki, Nathan; Lee, Cheng S.; Beamesderfer, Mike; DeVoe, Don L.

    2003-01-01

    A new Bio-MEMS electroosmotic flow (EOF) modulator for plastic microchannel networks has been developed. The EOF modulator uses field-effect flow control (FEFC) to adjust the zeta potential at the Parylene C microchannel wall. By setting a differential EOF pumping rate in two of the three microchannels at a T-intersection with EOF modulators, the induced pressure at the intersection generated pumping in the third, field-free microchannel. The EOF modulators are able to change the magnitude and direction of the pressure pumping by inducing either a negative or positive pressure at the intersection. The flow velocity is tracked by neutralized fluorescent microbeads in the microchannels. The proof-of-concept of the EOF modulator described here may be applied to complex plastic ,microchannel networks where individual microchannel flow rates are addressable by localized induced-pressure pumping.

  4. Pump and Flow Control Subassembly of Thermal Control Subsystem for Photovoltaic Power Module

    Science.gov (United States)

    Motil, Brian; Santen, Mark A.

    1993-01-01

    The pump and flow control subassembly (PFCS) is an orbital replacement unit (ORU) on the Space Station Freedom photovoltaic power module (PVM). The PFCS pumps liquid ammonia at a constant rate of approximately 1170 kg/hr while providing temperature control by flow regulation between the radiator and the bypass loop. Also, housed within the ORU is an accumulator to compensate for fluid volumetric changes as well as the electronics and firmware for monitoring and control of the photovoltaic thermal control system (PVTCS). Major electronic functions include signal conditioning, data interfacing and motor control. This paper will provide a description of each major component within the PFCS along with performance test data. In addition, this paper will discuss the flow control algorithm and describe how the nickel hydrogen batteries and associated power electronics will be thermally controlled through regulation of coolant flow to the radiator.

  5. Phase Resolved Angular Velocity Control of Cross Flow Turbines

    Science.gov (United States)

    Strom, Benjamin; Brunton, Steven; Polagye, Brian

    2015-11-01

    Cross flow turbines have a number of operational advantages for the conversion of kinetic energy in marine or fluvial currents, but they are often less efficient than axial flow devices. Here a control scheme is presented in which the angular velocity of a cross flow turbine with two straight blades is prescribed as a function of azimuthal blade position, altering the time-varying effective angle of attack. Flume experiments conducted with a scale model turbine show approximately an 80% increase in turbine efficiency versus optimal constant angular velocity and constant resistive torque control schemes. Torque, drag, and lateral forces on one- and two-bladed turbines are analyzed and interpreted with bubble flow visualization to develop a simple model that describes the hydrodynamics responsible for the observed increase in mean efficiency. Challenges associated with implementing this control scheme on commercial-scale devices are discussed. If solutions are found, the performance increase presented here may impact the future development of cross flow turbines.

  6. Tutorial on Feedback Control of Flows, Part I: Stabilization of Fluid Flows in Channels and Pipes

    Directory of Open Access Journals (Sweden)

    Ole M. Aamo

    2002-07-01

    Full Text Available The field of flow control has picked up pace over the past decade or so, on the promise of real-time distributed control on turbulent scales being realizable in the near future. This promise is due to the micromachining technology that emerged in the 1980s and developed at an amazing speed through the 1990s. In lab experiments, so called micro-electro-mechanical systems (MEMS that incorporate the entire detection-decision-actuation process on a single chip, have been batch processed in large numbers and assembled into flexible skins for gluing onto body-fluid interfaces for drag reduction purposes. Control of fluid flows span a wide variety of specialities. In Part I of this tutorial, we focus on the problem of reducing drag in channel and pipe flows by stabilizing the parabolic equilibrium profile using boundary feedback control. The control strategics used for this problem include classical control, based on the Nyquist criteria, and various optimal control techniques (H2, H-Infinity, as well as applications of Lyapunov stability theory.

  7. Intracycle angular velocity control of cross-flow turbines

    Science.gov (United States)

    Strom, Benjamin; Brunton, Steven L.; Polagye, Brian

    2017-08-01

    Cross-flow turbines, also known as vertical-axis turbines, are attractive for power generation from wind and water currents. Some cross-flow turbine designs optimize unsteady fluid forces and maximize power output by controlling blade kinematics within one rotation. One established method is to dynamically pitch the blades. Here we introduce a mechanically simpler alternative: optimize the turbine rotation rate as a function of angular blade position. We demonstrate experimentally that this approach results in a 59% increase in power output over standard control methods. Analysis of fluid forcing and blade kinematics suggest that power increase is achieved through modification of the local flow conditions and alignment of fluid force and rotation rate extrema. The result is a low-speed, structurally robust turbine that achieves high efficiency and could enable a new generation of environmentally benign turbines for renewable power generation.

  8. ac power control in the Core Flow Test Loop

    International Nuclear Information System (INIS)

    McDonald, D.W.

    1980-01-01

    This work represents a status report on a development effort to design an ac power controller for the Core Flow Test Loop. The Core Flow Test Loop will be an engineering test facility which will simulate the thermal environment of a gas-cooled fast-breeder reactor. The problems and limitations of using sinusoidal ac power to simulate the power generated within a nuclear reactor are addressed. The transformer-thyristor configuration chosen for the Core Flow Test Loop power supply is presented. The initial considerations, design, and analysis of a closed-loop controller prototype are detailed. The design is then analyzed for improved performance possibilities and failure modes are investigated at length. A summary of the work completed to date and a proposed outline for continued development completes the report

  9. Control volume based modelling of compressible flow in reciprocating machines

    DEFF Research Database (Denmark)

    Andersen, Stig Kildegård; Thomsen, Per Grove; Carlsen, Henrik

    2004-01-01

    , and multidimensional effects must be calculated using empirical correlations; correlations for steady state flow can be used as an approximation. A transformation that assumes ideal gas is presented for transforming equations for masses and energies in control volumes into the corresponding pressures and temperatures......An approach to modelling unsteady compressible flow that is primarily one dimensional is presented. The approach was developed for creating distributed models of machines with reciprocating pistons but it is not limited to this application. The approach is based on the integral form of the unsteady...... conservation laws for mass, energy, and momentum applied to a staggered mesh consisting of two overlapping strings of control volumes. Loss mechanisms can be included directly in the governing equations of models by including them as terms in the conservation laws. Heat transfer, flow friction...

  10. Variability of sap flow on forest hillslopes: patterns and controls

    Science.gov (United States)

    Hassler, Sibylle; Blume, Theresa

    2013-04-01

    Sap flow in trees is an essential variable in integrated studies of hydrologic fluxes. It gives indication of transpiration rates for single trees and, with a suitable method of upscaling, for whole stands. This information is relevant for hydrologic and climate models, especially for the prediction of change in water fluxes in the soil-plant-atmosphere continuum under climate change. To this end, we do not only need knowledge concerning the response of sapflow to atmospheric forcing but also an understanding of the main controls on its spatial variability. Our study site consists of several subcatchments of the Attert basin in Luxembourg underlain by schists of the Ardennes massif. Within these subcatchments we measure sap flow in more than 20 trees on a range of forested hillslopes covered by a variety of temperate deciduous tree species such as beech, oak, hornbeam and maple as well as conifers such as firs. Our sap flow sensors are based on the heat pulse velocity method and consist of three needles, one needle acting as the heating device and the other two holding three thermistors each, enabling us to simultaneously measure sap flow velocity at three different depths within the tree. In close proximity to the trees we collect additional data on soil moisture, matric potential and groundwater levels. First results show that the sensor design seems promising for an upscaling of the measured sap flow velocities to sap flow at the tree level. The maximum depth of actively used sapwood as well as the decrease in sap flow velocity with increasing depth in the tree can be determined by way of the three thermistors. Marked differences in sap flow velocity profiles are visible between the different species, resulting in differences in sap flow for trees of similar diameter. We examine the range of tree sap flow values and variation due to species, size class, slope position and exposition and finally relate them to the dynamics of soil moisture conditions with the

  11. Evaluation of the FAA Advanced Flow Control Procedures.

    Science.gov (United States)

    1972-01-01

    The report is an evaluation of the present FAA Advanced Flow Control Procedures (AFCP), based on data gathered from its implementation on February 5, 1971 and on a fast-time digital simulation of traffic feeding into the NY airports on that day. The ...

  12. Flow intake control using dry-weather forecast

    Science.gov (United States)

    Icke, Otto; van Schagen, Kim; Huising, Christian; Wuister, Jasper; van Dijk, Edward; Budding, Arjan

    2017-08-01

    Level-based control of the influent flow causes peak discharges at a waste water treatment plant (WWTP) after rainfall events. Furthermore, the capacity of the post-treatment is in general smaller than the maximum hydraulic capacity of the WWTP. This results in a significant bypass of the post-treatment during peak discharge. The optimisation of influent flow reduces peak discharge, and increases the treatment efficiency of the whole water cycle, which benefits the surface water quality. In this paper, it is shown that half of the bypasses of the post-treatment can be prevented by predictive control. A predictive controller for influent flow is implemented using the Aquasuitetext">® Advanced Monitoring and Control platform. Based on real-time measured water levels in the sewerage and both rainfall and dry-weather flow (DWF) predictions, a discharge limitation is determined by a volume optimisation technique. For the analysed period (February-September 2016) results at WWTP Bennekom show that about 50 % of bypass volume can be prevented. Analysis of single rainfall events shows that the used approach is still conservative and that the bypass can be even further decreased by allowing discharge limitation during precipitation.

  13. A stochastic programming approach to manufacturing flow control

    OpenAIRE

    Haurie, Alain; Moresino, Francesco

    2012-01-01

    This paper proposes and tests an approximation of the solution of a class of piecewise deterministic control problems, typically used in the modeling of manufacturing flow processes. This approximation uses a stochastic programming approach on a suitably discretized and sampled system. The method proceeds through two stages: (i) the Hamilton-Jacobi-Bellman (HJB) dynamic programming equations for the finite horizon continuous time stochastic control problem are discretized over a set of sample...

  14. Biological control of schistosome transmission in flowing water habitats.

    Science.gov (United States)

    Jobin, W R; Laracuente, A

    1979-09-01

    Marisa cornuarietis was evaluated in Puerto Rico for control of schistosome transmission in flowing water. A population of Biomphalaria glabrata and their schistosome infections disappeared after introduction of 20,000 M. cornuarietis to an endemic stream, while in nearby untreated streams the B. glabrata population remained stable and the schistosome prevalence increased. This method cost U.S. $0.10 per capita for over a year of protection, 5%-10% of the cost of chemical control.

  15. Nocturnal insects use optic flow for flight control

    OpenAIRE

    Baird, Emily; Kreiss, Eva; Wcislo, William; Warrant, Eric; Dacke, Marie

    2011-01-01

    To avoid collisions when navigating through cluttered environments, flying insects must control their flight so that their sensory systems have time to detect obstacles and avoid them. To do this, day-active insects rely primarily on the pattern of apparent motion generated on the retina during flight (optic flow). However, many flying insects are active at night, when obtaining reliable visual information for flight control presents much more of a challenge. To assess whether nocturnal flyin...

  16. Microrelief-Controlled Overland Flow Generation: Laboratory and Field Experiments

    Directory of Open Access Journals (Sweden)

    Xuefeng Chu

    2015-01-01

    Full Text Available Surface microrelief affects overland flow generation and the related hydrologic processes. However, such influences vary depending on other factors such as rainfall characteristics, soil properties, and initial soil moisture conditions. Thus, in-depth research is needed to better understand and evaluate the combined effects of these factors on overland flow dynamics. The objective of this experimental study was to examine how surface microrelief, in conjunction with the factors of rainfall, soil, and initial moisture conditions, impacts overland flow generation and runoff processes in both laboratory and field settings. A series of overland flow experiments were conducted for rough and smooth surfaces that represented distinct microtopographic characteristics and the experimental data were analyzed and compared. Across different soil types and initial moisture conditions, both laboratory and field experiments demonstrated that a rough soil surface experienced a delayed initiation of runoff and featured a stepwise threshold flow pattern due to the microrelief-controlled puddle filling-spilling-merging dynamics. It was found from the field experiments that a smooth plot surface was more responsive to rainfall variations especially during an initial rainfall event. However, enhanced capability of overland flow generation and faster puddle connectivity of a rough field plot occurred during the subsequent rain events.

  17. Flow Control in Wells Turbines for Harnessing Maximum Wave Power

    Science.gov (United States)

    Garrido, Aitor J.; Garrido, Izaskun; Otaola, Erlantz; Maseda, Javier

    2018-01-01

    Oceans, and particularly waves, offer a huge potential for energy harnessing all over the world. Nevertheless, the performance of current energy converters does not yet allow us to use the wave energy efficiently. However, new control techniques can improve the efficiency of energy converters. In this sense, the plant sensors play a key role within the control scheme, as necessary tools for parameter measuring and monitoring that are then used as control input variables to the feedback loop. Therefore, the aim of this work is to manage the rotational speed control loop in order to optimize the output power. With the help of outward looking sensors, a Maximum Power Point Tracking (MPPT) technique is employed to maximize the system efficiency. Then, the control decisions are based on the pressure drop measured by pressure sensors located along the turbine. A complete wave-to-wire model is developed so as to validate the performance of the proposed control method. For this purpose, a novel sensor-based flow controller is implemented based on the different measured signals. Thus, the performance of the proposed controller has been analyzed and compared with a case of uncontrolled plant. The simulations demonstrate that the flow control-based MPPT strategy is able to increase the output power, and they confirm both the viability and goodness. PMID:29439408

  18. Flow Control in Wells Turbines for Harnessing Maximum Wave Power.

    Science.gov (United States)

    Lekube, Jon; Garrido, Aitor J; Garrido, Izaskun; Otaola, Erlantz; Maseda, Javier

    2018-02-10

    Oceans, and particularly waves, offer a huge potential for energy harnessing all over the world. Nevertheless, the performance of current energy converters does not yet allow us to use the wave energy efficiently. However, new control techniques can improve the efficiency of energy converters. In this sense, the plant sensors play a key role within the control scheme, as necessary tools for parameter measuring and monitoring that are then used as control input variables to the feedback loop. Therefore, the aim of this work is to manage the rotational speed control loop in order to optimize the output power. With the help of outward looking sensors, a Maximum Power Point Tracking (MPPT) technique is employed to maximize the system efficiency. Then, the control decisions are based on the pressure drop measured by pressure sensors located along the turbine. A complete wave-to-wire model is developed so as to validate the performance of the proposed control method. For this purpose, a novel sensor-based flow controller is implemented based on the different measured signals. Thus, the performance of the proposed controller has been analyzed and compared with a case of uncontrolled plant. The simulations demonstrate that the flow control-based MPPT strategy is able to increase the output power, and they confirm both the viability and goodness.

  19. Integrated Lateral Flow Device for Flow Control with Blood Separation and Biosensing

    Directory of Open Access Journals (Sweden)

    Veronica Betancur

    2017-12-01

    Full Text Available Lateral flow devices are versatile and serve a wide variety of purposes, including medical, agricultural, environmental, and military applications. Yet, the most promising opportunities of these devices for diagnosis might reside in point-of-care (POC applications. Disposable paper-based lateral flow strips have been of particular interest, because they utilize low-cost materials and do not require expensive fabrication instruments. However, there are constraints on tuning flow rates and immunoassays functionalization in papers, as well as technical challenges in sensors’ integration and concentration units for low-abundant molecular detection. In the present work, we demonstrated an integrated lateral flow device that applied the capillary forces with functionalized polymer-based microfluidics as a strategy to realize a portable, simplified, and self-powered lateral flow device (LFD. The polydimethylsiloxane (PDMS surface was rendered hydrophilic via functionalization with different concentrations of Pluronic F127. Controlled flow is a key variable for immunoassay-based applications for providing enough time for protein binding to antibodies. The flow rate of the integrated LFD was regulated by the combination of multiple factors, including Pluronic F127 functionalized surface properties and surface treatments of microchannels, resistance of the integrated flow resistor, the dimensions of the microstructures and the spacing between them in the capillary pump, the contact angles, and viscosity of the fluids. Various plasma flow rates were regulated and achieved in the whole device. The LFD combined the ability to separate high quality plasma from human whole blood by using a highly asymmetric plasma separation membrane, and created controlled and steady fluid flow using capillary forces produced by the interfacial tensions. Biomarker immunoglobulin G (IgG detection from plasma was demonstrated with a graphene nanoelectronic sensor integrated

  20. Typing Local Control and State Using Flow Analysis

    Science.gov (United States)

    Guha, Arjun; Saftoiu, Claudiu; Krishnamurthi, Shriram

    Programs written in scripting languages employ idioms that confound conventional type systems. In this paper, we highlight one important set of related idioms: the use of local control and state to reason informally about types. To address these idioms, we formalize run-time tags and their relationship to types, and use these to present a novel strategy to integrate typing with flow analysis in a modular way. We demonstrate that in our separation of typing and flow analysis, each component remains conventional, their composition is simple, but the result can handle these idioms better than either one alone.

  1. Analysis of flow instability in steam turbine control valves

    International Nuclear Information System (INIS)

    Pluviose, M.

    1981-01-01

    With the sponsorship of Electricite de France and the French steam turbine manufacturers, the Gas Turbine Laboratory of CETIM has started a research about the unsteady phenomena of flow in control valves of steam turbines. The existence of unsteady embossment in the valve cone at rise has been as certained, and a conventional computing procedure has been applied to locate the shock waves in the valve. These shock waves may suddenly arise at some valve lifts and give way to fluttering. Valve geometries attenuating instability of flow and increasing therefore the reliability of such equipment are proposed [fr

  2. Quantifying, characterizing, and controlling information flow in ultracold atomic gases

    International Nuclear Information System (INIS)

    Haikka, P.; McEndoo, S.; Maniscalco, S.; De Chiara, G.; Palma, G. M.

    2011-01-01

    We study quantum information flow in a model comprised of a trapped impurity qubit immersed in a Bose-Einstein-condensed reservoir. We demonstrate how information flux between the qubit and the condensate can be manipulated by engineering the ultracold reservoir within experimentally realistic limits. We show that this system undergoes a transition from Markovian to non-Markovian dynamics, which can be controlled by changing key parameters such as the condensate scattering length. In this way, one can realize a quantum simulator of both Markovian and non-Markovian open quantum systems, the latter ones being characterized by a reverse flow of information from the background gas (reservoir) to the impurity (system).

  3. Automatized material and radioactivity flow control tool in decommissioning process

    International Nuclear Information System (INIS)

    Rehak, I.; Vasko, M.; Daniska, V.; Schultz, O.

    2009-01-01

    In this presentation the automatized material and radioactivity flow control tool in decommissioning process is discussed. It is concluded that: computer simulation of the decommissioning process is one of the important attributes of computer code Omega; one of the basic tools of computer optimisation of decommissioning waste processing are the tools of integral material and radioactivity flow; all the calculated parameters of materials are stored in each point of calculation process and they can be viewed; computer code Omega represents opened modular system, which can be improved; improvement of the module of optimisation of decommissioning waste processing will be performed in the frame of improvement of material procedures and scenarios.

  4. Fluidic actuators for active flow control on airframe

    Science.gov (United States)

    Schueller, M.; Weigel, P.; Lipowski, M.; Meyer, M.; Schlösser, P.; Bauer, M.

    2016-04-01

    One objective of the European Projects AFLoNext and Clean Sky 2 is to apply Active Flow Control (AFC) on the airframe in critical aerodynamic areas such as the engine/wing junction or the outer wing region for being able to locally improve the aerodynamics in certain flight conditions. At the engine/wing junction, AFC is applied to alleviate or even eliminate flow separation at low speeds and high angle of attacks likely to be associated with the integration of underwing- mounted Ultra High Bypass Ratio (UHBR) engines and the necessary slat-cut-outs. At the outer wing region, AFC can be used to allow more aggressive future wing designs with improved performance. A relevant part of the work on AFC concepts for airframe application is the development of suitable actuators. Fluidic Actuated Flow Control (FAFC) has been introduced as a Flow Control Technology that influences the boundary layer by actively blowing air through slots or holes out of the aircraft skin. FAFC actuators can be classified by their Net Mass Flux and accordingly divided into ZNMF (Zero Net Mass Flux) and NZNMF (Non Zero Net-Mass-Flux) actuators. In the frame of both projects, both types of the FAFC actuator concepts are addressed. In this paper, the objectives of AFC on the airframe is presented and the actuators that are used within the project are discussed.

  5. Stabilising falling liquid film flows using feedback control

    Energy Technology Data Exchange (ETDEWEB)

    Thompson, Alice B., E-mail: alice.thompson1@imperial.ac.uk; Gomes, Susana N.; Pavliotis, Grigorios A.; Papageorgiou, Demetrios T. [Department of Mathematics, Imperial College London, London SW7 2AZ (United Kingdom)

    2016-01-15

    Falling liquid films become unstable due to inertial effects when the fluid layer is sufficiently thick or the slope sufficiently steep. This free surface flow of a single fluid layer has industrial applications including coating and heat transfer, which benefit from smooth and wavy interfaces, respectively. Here, we discuss how the dynamics of the system are altered by feedback controls based on observations of the interface height, and supplied to the system via the perpendicular injection and suction of fluid through the wall. In this study, we model the system using both Benney and weighted-residual models that account for the fluid injection through the wall. We find that feedback using injection and suction is a remarkably effective control mechanism: the controls can be used to drive the system towards arbitrary steady states and travelling waves, and the qualitative effects are independent of the details of the flow modelling. Furthermore, we show that the system can still be successfully controlled when the feedback is applied via a set of localised actuators and only a small number of system observations are available, and that this is possible using both static (where the controls are based on only the most recent set of observations) and dynamic (where the controls are based on an approximation of the system which evolves over time) control schemes. This study thus provides a solid theoretical foundation for future experimental realisations of the active feedback control of falling liquid films.

  6. Nocturnal insects use optic flow for flight control.

    Science.gov (United States)

    Baird, Emily; Kreiss, Eva; Wcislo, William; Warrant, Eric; Dacke, Marie

    2011-08-23

    To avoid collisions when navigating through cluttered environments, flying insects must control their flight so that their sensory systems have time to detect obstacles and avoid them. To do this, day-active insects rely primarily on the pattern of apparent motion generated on the retina during flight (optic flow). However, many flying insects are active at night, when obtaining reliable visual information for flight control presents much more of a challenge. To assess whether nocturnal flying insects also rely on optic flow cues to control flight in dim light, we recorded flights of the nocturnal neotropical sweat bee, Megalopta genalis, flying along an experimental tunnel when: (i) the visual texture on each wall generated strong horizontal (front-to-back) optic flow cues, (ii) the texture on only one wall generated these cues, and (iii) horizontal optic flow cues were removed from both walls. We find that Megalopta increase their groundspeed when horizontal motion cues in the tunnel are reduced (conditions (ii) and (iii)). However, differences in the amount of horizontal optic flow on each wall of the tunnel (condition (ii)) do not affect the centred position of the bee within the flight tunnel. To better understand the behavioural response of Megalopta, we repeated the experiments on day-active bumble-bees (Bombus terrestris). Overall, our findings demonstrate that despite the limitations imposed by dim light, Megalopta-like their day-active relatives-rely heavily on vision to control flight, but that they use visual cues in a different manner from diurnal insects. This journal is © 2011 The Royal Society

  7. Strategic Management Accounting in Organizations’ Cash Flow Control

    Directory of Open Access Journals (Sweden)

    Y. P. Vetrov

    2017-09-01

    Full Text Available The article deals with the various interpretations of the term "strategic management accounting". The role and importance of strategic management accounting in the organization’s cash flows control are investigated. The accounting and analytical models of strategic management accounting are analyzed. The territorial scope of this article covers the Russian Federation. The study concludes that the system of assessment parameters of organization’s financial condition should cover all its aspects, namely, financial sustainability, solvency, liquidity and business activity. Hence, strategic management accounting of cash flows makes it possible to correctly set information base to monitor financial flows of a company which responds the tends of market economy and allows to make optimal management decisions.

  8. DESIGN OF SLIT DAMS FOR CONTROLLING STONY DEBRIS FLOWS

    Institute of Scientific and Technical Information of China (English)

    Hui-Pang LIEN

    2003-01-01

    A new method to a slit dam for controlling the stony debris flow has been derived based on the mass conservation law of the stony debris flow passing through a slit dam and the laboratory experiment results.This new method is then combined with three primary efficiency expressions: the dimensionless sediment outflow ratio,the sediment concentration ratio,and the sediment storage rate to develop a simple module,with which the height and the spacing of the posts,as well as the total spacing of slit dam are determined.Furthermore,these expressions can also be applied to check those slit dams that have already been constructed with their effectiveness against various magnitudes of the debris flow. The comparison between these expressions and laboratory data is in reasonable agreement.

  9. Numerical Studies of a Fluidic Diverter for Flow Control

    Science.gov (United States)

    Gokoglu, Suleyman A.; Kuczmarski, Maria A.; Culley, Dennis E.; Raghu, Surya

    2009-01-01

    The internal flow structure in a specific fluidic diverter is studied over a range from low subsonic to sonic inlet conditions by a time-dependent numerical analysis. The understanding will aid in the development of fluidic diverters with minimum pressure losses and advanced designs of flow control actuators. The velocity, temperature and pressure fields are calculated for subsonic conditions and the self-induced oscillatory behavior of the flow is successfully predicted. The results of our numerical studies have excellent agreement with our experimental measurements of oscillation frequencies. The acoustic speed in the gaseous medium is determined to be a key factor for up to sonic conditions in governing the mechanism of initiating the oscillations as well as determining its frequency. The feasibility of employing plasma actuation with a minimal perturbation level is demonstrated in steady-state calculations to also produce oscillation frequencies of our own choosing instead of being dependent on the fixed-geometry fluidic device.

  10. Flow induced vibration studies on PFBR control plug components

    Energy Technology Data Exchange (ETDEWEB)

    Prakash, V., E-mail: prakash@igcar.gov.in [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu (India); Kumar, P. Anup; Anandaraj, M.; Thirumalai, M.; Anandbabu, C.; Rajan, K.K. [Fast Reactor Technology Group, Indira Gandhi Centre for Atomic Research, Kalpakkam, Tamilnadu (India)

    2012-09-15

    Highlights: Black-Right-Pointing-Pointer Flow induced vibration studies on Prototype Fast Breeder Reactor control plug model carried out. Black-Right-Pointing-Pointer Velocity similitude was followed for the study. Black-Right-Pointing-Pointer Frequencies and amplitude of vibrations of various control plug components measured. Black-Right-Pointing-Pointer Overall values of vibration are well within permissible limits. - Abstract: The construction of Prototype Fast Breeder Reactor (PFBR), a 500 MWe liquid sodium cooled reactor, is in progress at Kalpakkam in India. Control plug (CP) is located right above the core subassemblies in the hot pool. Control plug is an important component as many of the critical reactor parameters are sensed and controlled by the components housed in the control plug assembly. In PFBR primary circuit, components are basically thin walled, slender shells with diameter to thickness ratio ranging from 100 to 650. These components are prone to flow induced vibrations. The existence of free liquid (sodium) surfaces, which is the source of sloshing phenomenon and the operation of primary sodium pump in the primary pool are other potential sources of vibration of reactor components. Control plug is a hollow cylindrical shell structure and provides passages and support for 12 absorber rod drive mechanisms (ARDM) which consists of 9 control and safety rods and 3 diverse safety rods, 210 thermo wells to measure the sodium temperature at the exit of various fuel subassemblies, three failed fuel localization modules (FFLM) and acoustic detectors. It consists of a core cover plate (CCP), which forms the bottom end, two intermediate supports plate, i.e. lower stay plate (LSP) and upper stay plate (USP) and an outer shell. The CCP is located at a distance of 1.3 m from the core top. With such a gap, there will be long free hanging length of the thermocouple sleeves, Delayed neutron detector (DND) sampling tubes and ARDM shroud tubes and hence they are

  11. Active Flow Control in an Aggressive Transonic Diffuser

    Science.gov (United States)

    Skinner, Ryan W.; Jansen, Kenneth E.

    2017-11-01

    A diffuser exchanges upstream kinetic energy for higher downstream static pressure by increasing duct cross-sectional area. The resulting stream-wise and span-wise pressure gradients promote extensive separation in many diffuser configurations. The present computational work evaluates active flow control strategies for separation control in an asymmetric, aggressive diffuser of rectangular cross-section at inlet Mach 0.7 and Re 2.19M. Corner suction is used to suppress secondary flows, and steady/unsteady tangential blowing controls separation on both the single ramped face and the opposite flat face. We explore results from both Spalart-Allmaras RANS and DDES turbulence modeling frameworks; the former is found to miss key physics of the flow control mechanisms. Simulated baseline, steady, and unsteady blowing performance is validated against experimental data. Funding was provided by Northrop Grumman Corporation, and this research used resources of the Argonne Leadership Computing Facility, which is a DOE Office of Science User Facility supported under Contract DE-AC02-06CH11357.

  12. Frequency dependence and frequency control of microbubble streaming flows

    Science.gov (United States)

    Wang, Cheng; Rallabandi, Bhargav; Hilgenfeldt, Sascha

    2013-02-01

    Steady streaming from oscillating microbubbles is a powerful actuating mechanism in microfluidics, enjoying increased use due to its simplicity of manufacture, ease of integration, low heat generation, and unprecedented control over the flow field and particle transport. As the streaming flow patterns are caused by oscillations of microbubbles in contact with walls of the set-up, an understanding of the bubble dynamics is crucial. Here we experimentally characterize the oscillation modes and the frequency response spectrum of such cylindrical bubbles, driven by a pressure variation resulting from ultrasound in the range of 1 kHz raisebox {-.9ex{stackrel{textstyle <}{˜ }} }f raisebox {-.9ex{stackrel{textstyle <}{˜ }} } 100 kHz. We find that (i) the appearance of 2D streaming flow patterns is governed by the relative amplitudes of bubble azimuthal surface modes (normalized by the volume response), (ii) distinct, robust resonance patterns occur independent of details of the set-up, and (iii) the position and width of the resonance peaks can be understood using an asymptotic theory approach. This theory describes, for the first time, the shape oscillations of a pinned cylindrical bubble at a wall and gives insight into necessary mode couplings that shape the response spectrum. Having thus correlated relative mode strengths and observed flow patterns, we demonstrate that the performance of a bubble micromixer can be optimized by making use of such flow variations when modulating the driving frequency.

  13. Climatic and geomorphic controls on low flow hydrograph recession

    Science.gov (United States)

    Chandler, D. G.; Daley, M.; Kasaee Roodsari, B.; Shaw, S. B.; McNamara, J.

    2017-12-01

    Large scale operational hydrologic models should be capable of predicting seasonally low flow and stream intermittency as well as peak flow and inundation. We contrast examples of controls on low flow exerted by geomorphic and climatic setting at small catchment study sites in the Northeast and Northwest of the USA to indicate differences in hydrologic processes. Both regions accumulate winter snowpack and have an extended spring freshet, but the Reynolds Creek CZO and Dry Creek Experimental Watershed (both in Idaho mountains) experience a protracted summer drought, with occasional storms whereas precipitation free periods greater than five days are uncommon in the hilly Sleepers River (Vermont), and Yellow Barn State Forest (New York) and at Ley Creek, on a glacial plain (New York). At both Dry Creek and Reynolds Creek, headwater stream flow direction was transverse to groundwater, and below field capacity discharge was well related to either the ground water surface or corresponded to inversion of the hydraulic gradient over the depth of the soil. At all sites except Ley Creek, the headwaters became intermittent as the main tributary discharge declined, often disconnecting the surface source springs and seeps from the valley bottom stream. At the Idaho sites recession analysis for main stem was further complicated by consumptive use for irrigation and domestic wells. Modeling the recession characteristics of these various settings and across stream orders results in a variety of exponent values for power law scaling approaches that indicate the importance of site context for modeling low flow.

  14. Flow control of micro-ramps on supersonic forward-facing step flow

    International Nuclear Information System (INIS)

    Zhang Qing-Hu; Zhu Tao; Wu Anping; Yi Shihe

    2016-01-01

    The effects of the micro-ramps on supersonic turbulent flow over a forward-facing step (FFS) was experimentally investigated in a supersonic low-noise wind tunnel at Mach number 3 using nano-tracer planar laser scattering (NPLS) and particle image velocimetry (PIV) techniques. High spatiotemporal resolution images and velocity fields of supersonic flow over the testing model were captured. The fine structures and their spatial evolutionary characteristics without and with the micro-ramps were revealed and compared. The large-scale structures generated by the micro-ramps can survive the downstream FFS flowfield. The micro-ramps control on the flow separation and the separation shock unsteadiness was investigated by PIV results. With the micro-ramps, the reduction in the range of the reversal flow zone in streamwise direction is 50% and the turbulence intensity is also reduced. Moreover, the reduction in the average separated region and in separation shock unsteadiness are 47% and 26%, respectively. The results indicate that the micro-ramps are effective in reducing the flow separation and the separation shock unsteadiness. (paper)

  15. CFD Study of NACA 0018 Airfoil with Flow Control

    Science.gov (United States)

    Eggert, Christopher A.; Rumsey, Christopher L.

    2017-01-01

    The abilities of two different Reynolds-Averaged Navier-Stokes codes to predict the effects of an active flow control device are evaluated. The flow control device consists of a blowing slot located on the upper surface of an NACA 0018 airfoil, near the leading edge. A second blowing slot present on the airfoil near mid-chord is not evaluated here. Experimental results from a wind tunnel test show that a slot blowing with high momentum coefficient will increase the lift of the airfoil (compared to no blowing) and delay flow separation. A slot with low momentum coefficient will decrease the lift and induce separation even at low angles of attack. Two codes, CFL3D and FUN3D, are used in two-dimensional computations along with several different turbulence models. Two of these produced reasonable results for this flow, when run fully turbulent. A more advanced transition model failed to predict reasonable results, but warrants further study using different inputs. Including inviscid upper and lower tunnel walls in the simulations was found to be important in obtaining pressure distributions and lift coefficients that best matched experimental data. A limited number of three-dimensional computations were also performed.

  16. Flow measurement and control in the defense waste process

    International Nuclear Information System (INIS)

    Heckendorn, F.M. II.

    1985-01-01

    The Defense Waste Processing Facility (DWPF) for immobilizing Savannah River Plant (SRP) high-level radioactive waste is now under construction. Previously stored waste is retrieved and processed into a glass matrix for permanent storage. The equipment operates in an entirely remote environment for both processing and maintenance due to the highly radioactive nature of the waste. A fine powdered glass frit is mixed with the waste prior to its introduction as a slurry into an electric glass furnace. The slurry is Bingham plastic in nature and of high viscosity. This combination of factors has created significant problems in flow measurement and control. Specialized pieces of equipment have been demonstrated that will function properly in a highly abrasive environment while receiving no maintenance during their lifetime. Included are flow meters, flow control technology, flow switching, and remote connections. No plastics or elastomers are allowed in contact with fluids and all electronic components are mounted remotely. Both two- and three-way valves are used. Maintenance is by crane replacement of process sections, utilizing specialized connectors. All portions of the above are now operating full scale (radioactively cold) at the test facility at SRP. 4 references, 8 figures

  17. Shuttle Gaseous Hydrogen Venting Risk from Flow Control Valve Failure

    Science.gov (United States)

    Drummond, J. Philip; Baurle, Robert A.; Gafney, Richard L.; Norris, Andrew T.; Pellett, Gerald L.; Rock, Kenneth E.

    2009-01-01

    This paper describes a series of studies to assess the potential risk associated with the failure of one of three gaseous hydrogen flow control valves in the orbiter's main propulsion system during the launch of Shuttle Endeavour (STS-126) in November 2008. The studies focused on critical issues associated with the possibility of combustion resulting from release of gaseous hydrogen from the external tank into the atmosphere during assent. The Shuttle Program currently assumes hydrogen venting from the external tank will result in a critical failure. The current effort was conducted to increase understanding of the risk associated with venting hydrogen given the flow control valve failure scenarios being considered in the Integrated In-Flight Anomaly Investigation being conducted by NASA.

  18. Particle size control of detergents in mixed flow spray dryers

    Directory of Open Access Journals (Sweden)

    Mark Jonathan Crosby

    2015-03-01

    Full Text Available Particle size is a key quality parameter of a powder detergent as it determines its performance, the bulk density and the look and feel of the product. Consequently, it is essential that particle size is controlled to ensure the consistency of performance when comparing new formulations. The majority of study reported in the literature relating to particle size control, focuses on the spray produced by the atomisation technique. One approach advocated to achieve particle size control is the manipulation of the ratio of the mass slurry rate and mass flow rate of gas used for atomisation. Within this study, ratio control was compared with an automatic cascade loop approach using online measurements of the powder particle size on a small-scale pilot plant. It was concluded that cascade control of the mean particle size, based on manipulating the mass flow rate of gas, resulted in tighter, more responsive control. The effect of a ratio change varied with different formulations and different slurry rates. Furthermore, changes in slurry rate caused complications, as the impact on particle size growth in the dryer is non-linear and difficult to predict. The cascade loop enables further study into the effect of particle size on detergent performance.

  19. Strategic Management Accounting in Organizations’ Cash Flow Control

    OpenAIRE

    Y. P. Vetrov; O. G. Vandina; A. R. Galustov

    2017-01-01

    The article deals with the various interpretations of the term "strategic management accounting". The role and importance of strategic management accounting in the organization’s cash flows control are investigated. The accounting and analytical models of strategic management accounting are analyzed. The territorial scope of this article covers the Russian Federation. The study concludes that the system of assessment parameters of organization’s financial condition should cover all its aspect...

  20. Experimental control of natural perturbations in channel flow

    OpenAIRE

    Juillet , Fabien; Mckeon , J.; Schmid , Peter J.

    2014-01-01

    International audience; A combined approach using system identification and feed-forward control design has been applied to experimental laminar channel flow in an effort to reduce the naturally occurring disturbance level. A simple blowing/suction strategy was capable of reducing the standard deviation of the measured sensor signal by 45 %, which markedly exceeds previously obtained results under comparable conditions. A comparable reduction could be verified over a significant streamwise ex...

  1. Thermal Mechanisms for High Amplitude Aerodynamic Flow Control (YIP 2012)

    Science.gov (United States)

    2016-04-15

    transport aircraft , much less cruise. The search for a perfect actuator continues, but progress has been limited by the often proprietary nature these...wave generation as a mechanism for high amplitude, high bandwidth actuation has been demonstrated, but the fundamental physics of how this...moving forward with such a definition. 15. SUBJECT TERMS active flow control, energy deposition, plasma actuation 16. SECURITY CLASSIFICATION OF: 17

  2. Industrial opportunities of controlled melt flow during glass melting, part 1: Melt flow evaluation

    Czech Academy of Sciences Publication Activity Database

    Dyrčíková, Petra; Hrbek, Lukáš; Němec, Lubomír

    2014-01-01

    Roč. 58, č. 2 (2014), s. 111-117 ISSN 0862-5468 R&D Projects: GA TA ČR TA01010844 Institutional support: RVO:67985891 Keywords : glass melting * controlled flow * space utilization Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.435, year: 2014 http://www.ceramics-silikaty.cz/2014/pdf/2014_02_111.pdf

  3. Empirical Reduced-Order Modeling for Boundary Feedback Flow Control

    Directory of Open Access Journals (Sweden)

    Seddik M. Djouadi

    2008-01-01

    Full Text Available This paper deals with the practical and theoretical implications of model reduction for aerodynamic flow-based control problems. Various aspects of model reduction are discussed that apply to partial differential equation- (PDE- based models in general. Specifically, the proper orthogonal decomposition (POD of a high dimension system as well as frequency domain identification methods are discussed for initial model construction. Projections on the POD basis give a nonlinear Galerkin model. Then, a model reduction method based on empirical balanced truncation is developed and applied to the Galerkin model. The rationale for doing so is that linear subspace approximations to exact submanifolds associated with nonlinear controllability and observability require only standard matrix manipulations utilizing simulation/experimental data. The proposed method uses a chirp signal as input to produce the output in the eigensystem realization algorithm (ERA. This method estimates the system's Markov parameters that accurately reproduce the output. Balanced truncation is used to show that model reduction is still effective on ERA produced approximated systems. The method is applied to a prototype convective flow on obstacle geometry. An H∞ feedback flow controller is designed based on the reduced model to achieve tracking and then applied to the full-order model with excellent performance.

  4. Evaluation of steady flow torques and pressure losses in a rotary flow control valve by means of computational fluid dynamics

    International Nuclear Information System (INIS)

    Okhotnikov, Ivan; Noroozi, Siamak; Sewell, Philip; Godfrey, Philip

    2017-01-01

    Highlights: • A novel design of a rotary flow control valve driven by a stepper motor is proposed. • The intended use of the valve in the high flow rate independent metering hydraulic system is suggested. • Pressure drops, steady flow torques of the valve for various flow rates and orifice openings are studied by means of computational fluid dynamics. • The discharge coefficient and flow jet angles dependencies on the orifice opening are obtained. • A design method to decrease the flow forces without reducing the flow rate in single-staged valves is demonstrated. - Abstract: In this paper, a novel design of a rotary hydraulic flow control valve has been presented for high flow rate fluid power systems. High flow rates in these systems account for substantial flow forces acting on the throttling elements of the valves and cause the application of mechanically sophisticated multi-staged servo valves for flow regulation. The suggested design enables utilisation of single-stage valves in power hydraulics operating at high flow rates regimes. A spool driver and auxiliary mechanisms of the proposed valve design were discussed and selection criteria were suggested. Analytical expressions for metering characteristics as well as steady flow torques have been derived. Computational fluid dynamics (CFD) analysis of steady state flow regimes was conducted to evaluate the hydraulic behaviour of the proposed valve. This study represents a special case of an independent metering concept applied to the design of power hydraulic systems with direct proportional valve control operating at flow rates above 150 litres per minute. The result gained using parametric CFD simulations predicted the induced torque and the pressure drops due to a steady flow. Magnitudes of these values prove that by minimising the number of spool's mobile metering surfaces it is possible to reduce the flow-generated forces in the new generation of hydraulic valves proposed in this study

  5. Modification of Flow Structure Over a Van Model By Suction Flow Control to Reduce Aerodynamics Drag

    Directory of Open Access Journals (Sweden)

    Harinaldi Harinaldi

    2012-05-01

    Full Text Available Automobile aerodynamic studies are typically undertaken to improve safety and increase fuel efficiency as well as to  find new innovation in automobile technology to deal with the problem of energy crisis and global warming. Some car companies have the objective to develop control solutions that enable to reduce the aerodynamic drag of vehicle and  significant modification progress is still possible by reducing the mass, rolling friction or aerodynamic drag. Some flow  control method provides the possibility to modify the flow separation to reduce the development of the swirling structures around the vehicle. In this study, a family van is modeled with a modified form of Ahmed's body by changing the orientation of the flow from its original form (modified/reversed Ahmed body. This model is equipped with a suction on the rear side to comprehensively examine the pressure field modifications that occur. The investigation combines computational and experimental work. Computational approach used  a commercial software with standard k-epsilon flow turbulence model, and the objectives was  to determine the characteristics of the flow field and aerodynamic drag reduction that occurred in the test model. Experimental approach used load cell in order to validate the aerodynamic drag reduction obtained by computational approach. The results show that the application of a suction in the rear part of the van model give the effect of reducing the wake and the vortex formation. Futhermore, aerodynamic drag reduction close to 13.86% for the computational approach and 16.32% for the experimental have been obtained.

  6. A flow-control mechanism for distributed systems

    Science.gov (United States)

    Maitan, J.

    1991-01-01

    A new approach to the rate-based flow control in store-and-forward networks is evaluated. Existing methods display oscillations in the presence of transport delays. The proposed scheme is based on the explicit use of an embedded dynamic model of a store-and-forward buffer in a controller's feedback loop. It is shown that the use of the model eliminates the oscillations caused by the transport delays. The paper presents simulation examples and assesses the applicability of the scheme in the new generation of high-speed photonic networks where transport delays must be considered.

  7. Control of energy flow in residential buildings; Energieflussregelung in Wohngebaeuden

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, Martin

    2011-07-01

    Energy systems in residential buildings are changing from monovalent, combustion based systems to multivalent systems containing technologies such as solar collectors, pellet boilers, heat pumps, CHP and multiple storages. Multivalent heat and electricity generation and additional storages raise the number of possible control signals in the system. This creates additional degrees of freedom regarding the choice of the energy converter and the instant of time for energy conversion. New functionality of controllers such as prioritisation of energy producers, optimization of electric self consumption and control of storages and energy feed-in are required. Within the scope of this thesis, new approaches for demand-driven optimal control of energy flows in multivalent building energy systems are developed and evaluated. The approaches are evaluated by means of system energy costs and operating emissions. For parametrisation of the controllers an easily understandable operating concept is developed. The energy flow controllers are implemented as a multi agent system (MAS) and a nonlinear model predictive controller (MPC). Proper functionality and stability are demonstrated in simulations of two example energy systems. In both example systems the MPC controller achieves less energy costs and operating emissions due to system wide global optimization and the more detailed system model within the controller. The multi agent approach turns out to perform better for systems with a huge number of components, e.g. in home automation and energy management systems. Due to the good performance of the reference control strategies, a significant reduction of energy costs and operating emissions is only possible with limitations. Systems for heat generation show only an especially low potential for optimization because of marginal variation ins heat production costs. The adaptation of the operation mode to user priorities, changing utilization characteristics and dynamic energy

  8. CRITICAL CONTROL POINTS ON THE TECHNOLOGICAL FLOW OF PANIFICATION

    Directory of Open Access Journals (Sweden)

    Gigel PARASCHIV

    2013-05-01

    Full Text Available Bread and panification products are intended for direct human consumption and underlying nutritional pyramid, it can affect the consumers health in case of biological, chemical or physical contamination, immediate or delayed, by noxious accumulation in the human organism. Only by rigorous compliance of the production rules throughout the technological process can ensure the quality and food safety of these products. If the risk can be prevented, eliminated or reduce to an acceptable level, as a result of a control actions made at that stage, it is considered a Critical Control Point (CCP. There can be checkpoints where it can exert a control action. Thus, the checkpoint is represented by any stage in which the risk factors, biological, chemical or physical, can be controlled in order to prevent, disrupt or reduce them to an acceptable level. This paper is referring to the control points on the technological flow of the bread fabrication, in all phases of this technological flow, laying stress on that points (or phases which can affect security and food safety, through the influence of parameters of any kind on the quality of finished products.

  9. Neural Network Predictive Control for Vanadium Redox Flow Battery

    Directory of Open Access Journals (Sweden)

    Hai-Feng Shen

    2013-01-01

    Full Text Available The vanadium redox flow battery (VRB is a nonlinear system with unknown dynamics and disturbances. The flowrate of the electrolyte is an important control mechanism in the operation of a VRB system. Too low or too high flowrate is unfavorable for the safety and performance of VRB. This paper presents a neural network predictive control scheme to enhance the overall performance of the battery. A radial basis function (RBF network is employed to approximate the dynamics of the VRB system. The genetic algorithm (GA is used to obtain the optimum initial values of the RBF network parameters. The gradient descent algorithm is used to optimize the objective function of the predictive controller. Compared with the constant flowrate, the simulation results show that the flowrate optimized by neural network predictive controller can increase the power delivered by the battery during the discharge and decrease the power consumed during the charge.

  10. Digital feedwater and recirculation flow control for GPUN Oyster Creek

    International Nuclear Information System (INIS)

    Burjorjee, D.; Gan, B.

    1992-01-01

    This paper describes the digital system for feedwater and recirculation control that GPU Nuclear will be installing at Oyster Creek during its next outage - expected circa December 1992. The replacement was motivated by considerations of reliability and obsolescence - the analog equipment was aging and reaching the end of its useful life. The new system uses Atomic Energy of Canada Ltd.'s software platform running on dual, redundant, industrial-grade 386 computers with opto-isolated field input/output (I/O) accessed through a parallel bus. The feedwater controller controls three main feed regulating valves, two low flow regulating valves, and two block valves. The recirculation controller drives the five scoop positioners of the hydraulic couplers. The system also drives contacts that lock up the actuators on detecting an open circuit in their current loops

  11. Proportional feedback control of laminar flow over a hemisphere

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jung Il [Dept. of Mechanical Engineering, Ajou University, Suwon (Korea, Republic of); Son, Dong Gun [Severe Accident and PHWR Safety Research Division, Korea Atomic Energy Research Institute (KAERI), Daejeon (Korea, Republic of)

    2016-08-15

    In the present study, we perform a proportional feedback control of laminar flow over a hemisphere at Re = 300 to reduce its lift fluctuations by attenuating the strength of the vortex shedding. As a control input, blowing/suction is distributed on the surface of hemisphere before the separation, and its strength is linearly proportional to the transverse velocity at a sensing location in the centerline of the wake. The sensing location is determined based on a correlation function between the lift force and the time derivative of sensing velocity. The optimal proportional gains for the proportional control are obtained for the sensing locations considered. The present control successfully attenuates the velocity fluctuations at the sensing location and three dimensional vertical structures in the wake, resulting in the reduction of lift fluctuations of hemisphere.

  12. "Batch" kinetics in flow: online IR analysis and continuous control.

    Science.gov (United States)

    Moore, Jason S; Jensen, Klavs F

    2014-01-07

    Currently, kinetic data is either collected under steady-state conditions in flow or by generating time-series data in batch. Batch experiments are generally considered to be more suitable for the generation of kinetic data because of the ability to collect data from many time points in a single experiment. Now, a method that rapidly generates time-series reaction data from flow reactors by continuously manipulating the flow rate and reaction temperature has been developed. This approach makes use of inline IR analysis and an automated microreactor system, which allowed for rapid and tight control of the operating conditions. The conversion/residence time profiles at several temperatures were used to fit parameters to a kinetic model. This method requires significantly less time and a smaller amount of starting material compared to one-at-a-time flow experiments, and thus allows for the rapid generation of kinetic data. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Participative planning and information flow within management control

    Directory of Open Access Journals (Sweden)

    Tomasz Dyczkowski

    2016-09-01

    Full Text Available The paper examines the relationships between two different approaches to planning processes (participa- tive and non-participative and information flows within management control in companies. It augments the existing theoretical and empirical research by coupling management control and management infor- mation with participative planning, not only in operational but also in the strategic perspective. The re- sults presented in the paper stem from two consecutive studies, conducted between November 2010 and January 2012 and between November 2013 and January 2014. The studies comprised 397 and 179 Polish companies respectively. The authors formulated two hypotheses linking participative planning with upward and downward management information flows. The paper employed a quantitative approach, using the Spearman rank correlation analysis and hierarchical clustering using the Ward method, which enabled comparative analyses both in reference to various groups of companies included in particular research samples and over time. The results obtained showed the positive influence of participative plan- ning both on upward and downward information flows in enterprises. In particular, participative planning reduced information imbalances between top (the management and lower (employees of functional departments tiers in organisation structures.

  14. Development of the flow control irradiation facility for JOYO

    International Nuclear Information System (INIS)

    Soroi, Masatoshi; Miyakawa, Shun-ichi

    1998-05-01

    This report describes the present situation and problems with the development of the flow control irradiation facility (FLORA). The purpose of FLORA is to run the cladding breach (RTCB) irradiation test under loss of flow conditions in the experimental fast reactor 'JOYO'. FLORA is a facility like FPTF (Fuel Performance Test Facility) plus BFTF (Breached Fuel Test Facility) in EBR-II, USA. The technical feature of FLORA is its annular linear induction pump (A-LIP), which was developed in response to a need identified through the experiences in the mechanical flow control of FPTF. We have already designed the basic system facility of FLORA for the JOYO MK-II core. However, to put FLORA to practical use in the future, we have to confirm the stability of the JOYO MK-III core condition, solve problems and improve the design. We are going to freeze and review the FLORA project, taking into consideration the fuel development situation and the research project of JOYO MK-III core. (J.P.N.)

  15. Drag reduction in channel flow using nonlinear control

    Science.gov (United States)

    Keefe, Laurence R.

    1993-01-01

    Two nonlinear control schemes have been applied to the problem of drag reduction in channel flow. Both schemes have been tested using numerical simulations at a mass flux Reynolds numbers of 4408, utilizing 2D nonlinear neutral modes for goal dynamics. The OGY-method, which requires feedback, reduces drag to 60-80 percent of the turbulent value at the same Reynolds number, and employs forcing only within a thin region near the wall. The H-method, or model-based control, fails to achieve any drag reduction when starting from a fully turbulent initial condition, but shows potential for suppressing or retarding laminar-to-turbulent transition by imposing instead a transition to a low drag, nonlinear traveling wave solution to the Navier-Stokes equation. The drag in this state corresponds to that achieved by the OGY-method. Model-based control requires no feedback, but in experiments to date has required the forcing be imposed within a thicker layer than the OGY-method. Control energy expenditures in both methods are small, representing less than 0.1 percent of the uncontrolled flow's energy.

  16. Control of open end plasma flow utilizing orbital stochasticity

    International Nuclear Information System (INIS)

    Hojo, Hitoshi

    1995-01-01

    It has been known that the control of plasma outside the confinement region of diverter plasma and others in a magnetic field confinement device is very important for improveing the confinement of bulk plasma. The control of plasma outside a confinement region bears two roles, one is the reduction of the thermal load on a diverter plate and others due to the plasma particles lost from the confinement region, and another is the restriction of the back flow of cold plasma and impurities generated outside the confinement region to a bulk plasma region. In this study, the new method of controlling plasma outside a confinement region called magnetic diverter is considered. To the plasma particles advancing along magnetic force lines, the reflection and capture of the plasma particles occur in the region of orbital stochasticity, and the thermal load on an end plate and the reverse flow to a bulk plasma region are restricted. The numerical computation model used regarding the particle control utilizing the orbital stochasticity and the results of calculating the orbit of plasma particles in a magnetic field are reported. (K.I.)

  17. Synthetic Jets Flow Control on a vertical stabilizer

    Science.gov (United States)

    Rathay, Nicholas; Boucher, Matthew; Amitay, Michael

    2011-11-01

    The vertical stabilizer on most commercial transport aircraft is much larger than required for stability and control. The tail is significantly oversized in order to maintain controllability in the event of asymmetric engine failure and meet flying qualities requirements related to dynamic motion. Using aerodynamic flow control techniques, it may be possible to reduce the size of the tail while maintaining similar control authority during inclement flight conditions. Reducing the size of the tail decreases the weight and the drag of the airplane, which results in considerable savings in fuel costs. In this work, it is shown that synthetic jet (zero-net-mass-flux) actuators are capable of reattaching the separated flow on the rudder and augmenting the performance of the stabilizer. Experiments were conducted in an open-return wind tunnel on a 1/25th scale model of a vertical stabilizer and a partial fuselage section. The surface pressure, aerodynamic loads and data acquired with a Stereo PIV system were used to investigate the effectiveness of this technology as well as provide a more detailed analysis of the flowfield and showed that the synthetic jets are capable of augmenting the side-force by up to 20%.

  18. Flow controls on lowland river macrophytes: a review.

    Science.gov (United States)

    Franklin, Paul; Dunbar, Michael; Whitehead, Paul

    2008-08-01

    We review the current status of knowledge regarding the role that flow parameters play in controlling the macrophyte communities of temperate lowland rivers. We consider both direct and indirect effects and the interaction with other factors known to control macrophyte communities. Knowledge gaps are identified and implications for the management of river systems considered. The main factors and processes controlling the status of macrophytes in lowland rivers are velocity (hence also discharge), light, substrate, competition, nutrient status and river management practices. We suggest that whilst the characteristics of any particular macrophyte community reflect the integral effects of a combination of the factors, fundamental importance can be attributed to the role of discharge and velocity in controlling instream macrophyte colonisation, establishment and persistence. Velocity and discharge also appear to control the relative influence of some of the other controlling factors. Despite the apparent importance of velocity in determining the status of macrophyte communities in lowland rivers, relatively little is understood about the nature of the processes controlling this relationship. Quantitative knowledge is particularly lacking. Consequently, the ability to predict macrophyte abundance and distribution in rivers is still limited. This is further complicated by the likely existence of feedback effects between the growth of macrophytes and velocity. Demand for water resources increases the pressure on lowland aquatic ecosystems. Despite growing recognition of the need to allocate water for the needs of instream biota, the inability to assess the flow requirements of macrophyte communities limits the scope to achieve this. This increases the likelihood of overexploitation of the water resource as other users, whose demands are quantifiable, are prioritised.

  19. Unsteady flow model for circulation-control airfoils

    Science.gov (United States)

    Rao, B. M.

    1979-01-01

    An analysis and a numerical lifting surface method are developed for predicting the unsteady airloads on two-dimensional circulation control airfoils in incompressible flow. The analysis and the computer program are validated by correlating the computed unsteady airloads with test data and also with other theoretical solutions. Additionally, a mathematical model for predicting the bending-torsion flutter of a two-dimensional airfoil (a reference section of a wing or rotor blade) and a computer program using an iterative scheme are developed. The flutter program has a provision for using the CC airfoil airloads program or the Theodorsen hard flap solution to compute the unsteady lift and moment used in the flutter equations. The adopted mathematical model and the iterative scheme are used to perform a flutter analysis of a typical CC rotor blade reference section. The program seems to work well within the basic assumption of the incompressible flow.

  20. Device for controlling a recirculation flow in a reactor

    International Nuclear Information System (INIS)

    Shida, Toichi; Tohei, Kazushige; Hirose, Masao; Nakamura, Hideo.

    1976-01-01

    Object: To provide an emergency cut-off valve in a recirculation system in a reactor to control the recirculation at the time of turbine trip or load cut-off, thereby relieving excessive increase in heat output of fuel. Structure: A recirculation pump is driven through a recirculation pump motor by an AC generator, which is driven by a driving motor through a fluid coupling, so that reactor water passes the emergency cut-off valve and recirculation flow stop valve and then passes a jet pump into the core. At the time of turbine trip or load cut-off, the emergency cut-off valve is closed by a hydraulic circuit, whereby core flow is merely decreased by 20 to 30% in a short period of time to restrain excessive increase in heat output. (Yoshino, Y.)

  1. Cerebral autoregulation control of blood flow in the brain

    CERN Document Server

    Payne, Stephen

    2016-01-01

    This Brief provides a comprehensive introduction to the control of blood flow in the brain. Beginning with the basic physiology of autoregulation, the author goes on to discuss measurement techniques, mathematical models, methods of analysis, and relevant clinical conditions, all within this single volume. The author draws together this disparate field, and lays the groundwork for future research directions. The text gives an up-to-date review of the state of the art in cerebral autoregulation, which is particularly relevant as cerebral autoregulation moves from the laboratory to the bedside. Cerebral Autoregulation will be useful to researchers in the physical sciences such as mathematical biology, medical physics, and biomedical engineering whose work is concerned with the brain. Researchers in the medical sciences and clinicians dealing with the brain and blood flow, as well as industry professionals developing techniques such as ultrasound, MRI, and CT will also find this Brief of interest.

  2. Computing an operating parameter of a unified power flow controller

    Science.gov (United States)

    Wilson, David G.; Robinett, III, Rush D.

    2017-12-26

    A Unified Power Flow Controller described herein comprises a sensor that outputs at least one sensed condition, a processor that receives the at least one sensed condition, a memory that comprises control logic that is executable by the processor; and power electronics that comprise power storage, wherein the processor causes the power electronics to selectively cause the power storage to act as one of a power generator or a load based at least in part upon the at least one sensed condition output by the sensor and the control logic, and wherein at least one operating parameter of the power electronics is designed to facilitate maximal transmittal of electrical power generated at a variable power generation system to a grid system while meeting power constraints set forth by the electrical power grid.

  3. Computing an operating parameter of a unified power flow controller

    Science.gov (United States)

    Wilson, David G; Robinett, III, Rush D

    2015-01-06

    A Unified Power Flow Controller described herein comprises a sensor that outputs at least one sensed condition, a processor that receives the at least one sensed condition, a memory that comprises control logic that is executable by the processor; and power electronics that comprise power storage, wherein the processor causes the power electronics to selectively cause the power storage to act as one of a power generator or a load based at least in part upon the at least one sensed condition output by the sensor and the control logic, and wherein at least one operating parameter of the power electronics is designed to facilitate maximal transmittal of electrical power generated at a variable power generation system to a grid system while meeting power constraints set forth by the electrical power grid.

  4. Multiphase flow dynamics and control; Dynamique et controle des ecoulements polyphasiques

    Energy Technology Data Exchange (ETDEWEB)

    Duret, E.

    2005-02-01

    Production in the petroleum industry requires a better knowledge of multiphase flow, as the design of pipelines may cause the flow to become strongly unstable. For instance, for low flow rates and when a sea line ends at a riser, the riser base may accumulate liquid and stop the flow of gas. Then, the upstream gas is compressed until its pressure is large enough to push the liquid slug downstream. Under such conditions, a cyclic process occurs which is called severe slugging, generating large and fast fluctuations in pressure and flow rates. This thesis is devoted to two methods to stabilize this undesirable phenomenon. Using the pipeline's ability to separate phases to pick-up the gas upstream the riser base, they are mainly based on the perturbation theory (fast proportional effect, slow integral effect). The first one uses a secondary riser to transport the gas to the surface facilities. A stability study worked out with the phase diagrams technique shows that it is a good method to control this phenomenon. However, it imposes a high pressure in all the system. Thus, the second controller re-injects the gas at a determined height in the riser to decrease the hydrostatic pressure. A first stability study in open loop give a criterion on the minimal reinjection height. Then, the controller is developed by using the two-time scale control techniques. Finally, let us denote that these two controllers have been validated with a small size experimental set up. (author)

  5. A nuclear data acquisition system flow control model

    International Nuclear Information System (INIS)

    Hack, S.N.

    1988-01-01

    A general Petri Net representation of a nuclear data acquisition system model is presented. This model provides for the unique requirements of a nuclear data acquisition system including the capabilities of concurrently acquiring asynchronous and synchronous data, of providing multiple priority levels of flow control arbitration, and of permitting multiple input sources to reside at the same priority without the problem of channel lockout caused by a high rate data source. Finally, a previously implemented gamma camera/physiological signal data acquisition system is described using the models presented

  6. Systematic realisation of control flow analyses for CML

    DEFF Research Database (Denmark)

    Gasser, K.L.S.; Nielson, Flemming; Nielson, Hanne Riis

    1997-01-01

    We present a methodology for the systematic realisation of control flow analyses and illustrate it for Concurrent ML. We start with an abstract specification of the analysis that is next proved semantically sound with respect to a traditional small-step operational semantics; this result holds......) to be defined in a syntax-directed manner, and (iii) to generate a set of constraints that subsequently can be solved by standard techniques. We prove equivalence results between the different versions of the analysis; in particular it follows that the least solution to the constraints generated...

  7. Metabolic control of muscle blood flow during exercise in humans

    DEFF Research Database (Denmark)

    Boushel, Robert Christopher

    2003-01-01

    that combined blockade of NOS and PGI2, and NOS and cytochrome P450, both attenuate exercise-induced hyperemia in humans. Combined vasodilator blockade studies offer the potential to uncover important interactions and compensatory vasodilator responses. The signaling pathways that link metabolic events evoked...... to exert control of muscle vasodilation. Adenosine, nitric oxide (NO), prostacyclin (PGI2), and endothelial-derived hyperpolarization factor (EDHF) are possible mediators of muscle vasodilation during exercise. In humans, adenosine has been shown to contribute to functional hyperemia as blood flow...... by muscle contraction to vasodilatory signals in the local vascular bed remains an important area of study....

  8. Jet flow and premixed jet flame control by plasma swirler

    Energy Technology Data Exchange (ETDEWEB)

    Li, Gang, E-mail: ligang@iet.cn [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Jiang, Xi [School of Engineering and Materials Science, Queen Mary University of London, Mile End Road, London E1 4NS (United Kingdom); Zhao, Yujun [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Liu, Cunxi [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China); Chen, Qi [School of Mechanism, Electronic and Control Engineering, Beijing Jiaotong University, Beijing 100044 (China); Xu, Gang; Liu, Fuqiang [Key laboratory of light duty gas turbine, Institute of Engineering Thermophysics, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-04-04

    A swirler based on dielectric barrier discharge plasma actuators is designed and its effectiveness in both jet flow and premixed jet flame control is demonstrated. In contrast to traditional spanwise-oriented actuators, plasma actuators are placed along the axial direction of the injector to induce a circumferential velocity to the main flow and create a swirl flow without any insertion or moving part. In the DBD plasma swirl injector, the discharge does not ignite the mixture nor does it induce flashback. Flame visualization is obtained by cameras while velocity profiles are obtained by Laser Doppler Anemometry measurements. The results obtained indicate the effectiveness of the new design. - Highlights: • The discharge does not ignite the mixture nor does it induce flashback. • The prominent advantage of this novel plasma swirler is its swirl number adjustable without any mechanical movement. • The frequency of the plasma swirler is adjustable. • The plasma swirler can be used as an oscillator to the reactants. • The plasma swirler can be used alone or combine with other traditional swirlers.

  9. Simulation Results of Closed Loop Controlled Interline Power Flow Controller System

    Directory of Open Access Journals (Sweden)

    P. USHA RANI

    2016-01-01

    Full Text Available The Interline Power Flow Controller (IPFC is the latest generation of Flexible AC Transmission Systems (FACTS devices which can be used to control power flows of multiple transmission lines. A dispatch strategy is proposed for an IPFC operating at rated capacity, in which the power circulation between the two series converters is used as the parameter to optimize the voltage profile and power transfer. Voltage stability curves for test system are shown to illustrate the effectiveness of this proposed strategy. In this paper, a circuit model for IPFC is developed and simulation of interline power flow controller is done using the proposed circuit model. Simulation is done using MATLAB simulink and the results are presented.

  10. Device for passive flow control around vertical axis marine turbine

    Science.gov (United States)

    Coşoiu, C. I.; Georgescu, A. M.; Degeratu, M.; Haşegan, L.; Hlevca, D.

    2012-11-01

    The power supplied by a turbine with the rotor placed in a free stream flow may be increased by augmenting the velocity in the rotor area. The energy of the free flow is dispersed and it may be concentrated by placing a profiled structure around the bare turbine in order to concentrate more energy in the rotor zone. At the Aerodynamic and Wind Engineering Laboratory (LAIV) of the Technical University of Civil Engineering of Bucharest (UTCB) it was developed a concentrating housing to be used for hydro or aeolian horizontal axis wind turbines, in order to increase the available energy in the active section of turbine rotor. The shape of the concentrating housing results by superposing several aero/hydro dynamic effects, the most important being the one generated by the passive flow control devices that were included in the housing structure. Those concentrating housings may be also adapted for hydro or aeolian turbines with vertical axis. The present paper details the numerical research effectuated at the LAIV to determine the performances of a vertical axis marine turbine equipped with such a concentrating device, in order to increase the energy quantity extracted from the main flow. The turbine is a Darrieus type one with three vertical straight blades, symmetric with respect to the axis of rotation, generated using a NACA4518 airfoil. The global performances of the turbine equipped with the concentrating housing were compared to the same characteristics of the bare turbine. In order to validate the numerical approach used in this paper, test cases from the literature resulting from experimental and numerical simulations for similar situations, were used.

  11. Device for passive flow control around vertical axis marine turbine

    International Nuclear Information System (INIS)

    Coşoiu, C I; Georgescu, A M; Degeratu, M; Haşegan, L; Hlevca, D

    2012-01-01

    The power supplied by a turbine with the rotor placed in a free stream flow may be increased by augmenting the velocity in the rotor area. The energy of the free flow is dispersed and it may be concentrated by placing a profiled structure around the bare turbine in order to concentrate more energy in the rotor zone. At the Aerodynamic and Wind Engineering Laboratory (LAIV) of the Technical University of Civil Engineering of Bucharest (UTCB) it was developed a concentrating housing to be used for hydro or aeolian horizontal axis wind turbines, in order to increase the available energy in the active section of turbine rotor. The shape of the concentrating housing results by superposing several aero/hydro dynamic effects, the most important being the one generated by the passive flow control devices that were included in the housing structure. Those concentrating housings may be also adapted for hydro or aeolian turbines with vertical axis. The present paper details the numerical research effectuated at the LAIV to determine the performances of a vertical axis marine turbine equipped with such a concentrating device, in order to increase the energy quantity extracted from the main flow. The turbine is a Darrieus type one with three vertical straight blades, symmetric with respect to the axis of rotation, generated using a NACA4518 airfoil. The global performances of the turbine equipped with the concentrating housing were compared to the same characteristics of the bare turbine. In order to validate the numerical approach used in this paper, test cases from the literature resulting from experimental and numerical simulations for similar situations, were used.

  12. Thermodynamic framework for discrete optimal control in multiphase flow systems

    Science.gov (United States)

    Sieniutycz, Stanislaw

    1999-08-01

    Bellman's method of dynamic programming is used to synthesize diverse optimization approaches to active (work producing) and inactive (entropy generating) multiphase flow systems. Thermal machines, optimally controlled unit operations, nonlinear heat conduction, spontaneous relaxation processes, and self-propagating wave fronts are all shown to satisfy a discrete Hamilton-Jacobi-Bellman equation and a corresponding discrete optimization algorithm of Pontryagin's type, with the maximum principle for a Hamiltonian. The extremal structures are always canonical. A common unifying criterion is set for all considered systems, which is the criterion of a minimum generated entropy. It is shown that constraints can modify the entropy functionals in a different way for each group of the processes considered; thus the resulting structures of these functionals may differ significantly. Practical conclusions are formulated regarding the energy savings and energy policy in optimally controlled systems.

  13. Bubble gate for in-plane flow control.

    Science.gov (United States)

    Oskooei, Ali; Abolhasani, Milad; Günther, Axel

    2013-07-07

    We introduce a miniature gate valve as a readily implementable strategy for actively controlling the flow of liquids on-chip, within a footprint of less than one square millimetre. Bubble gates provide for simple, consistent and scalable control of liquid flow in microchannel networks, are compatible with different bulk microfabrication processes and substrate materials, and require neither electrodes nor moving parts. A bubble gate consists of two microchannel sections: a liquid-filled channel and a gas channel that intercepts the liquid channel to form a T-junction. The open or closed state of a bubble gate is determined by selecting between two distinct gas pressure levels: the lower level corresponds to the "open" state while the higher level corresponds to the "closed" state. During closure, a gas bubble penetrates from the gas channel into the liquid, flanked by a column of equidistantly spaced micropillars on each side, until the flow of liquid is completely obstructed. We fabricated bubble gates using single-layer soft lithographic and bulk silicon micromachining procedures and evaluated their performance with a combination of theory and experimentation. We assessed the dynamic behaviour during more than 300 open-and-close cycles and report the operating pressure envelope for different bubble gate configurations and for the working fluids: de-ionized water, ethanol and a biological buffer. We obtained excellent agreement between the experimentally determined bubble gate operational envelope and a theoretical prediction based on static wetting behaviour. We report case studies that serve to illustrate the utility of bubble gates for liquid sampling in single and multi-layer microfluidic devices. Scalability of our strategy was demonstrated by simultaneously addressing 128 bubble gates.

  14. Flow control at low Reynolds numbers using periodic airfoil morphing

    Science.gov (United States)

    Jones, Gareth; Santer, Matthew; Papadakis, George; Bouremel, Yann; Debiasi, Marco; Imperial-NUS Joint PhD Collaboration

    2014-11-01

    The performance of airfoils operating at low Reynolds numbers is known to suffer from flow separation even at low angles of attack as a result of their boundary layers remaining laminar. The lack of mixing---a characteristic of turbulent boundary layers---leaves laminar boundary layers with insufficient energy to overcome the adverse pressure gradient that occurs in the pressure recovery region. This study looks at periodic surface morphing as an active flow control technique for airfoils in such a flight regime. It was discovered that at sufficiently high frequencies an oscillating surface is capable of not only reducing the size of the separated region---and consequently significantly reducing drag whilst simultaneously increasing lift---but it is also capable of delaying stall and as a result increasing CLmax. Furthermore, by bonding Macro Fiber Composite actuators (MFCs) to the underside of an airfoil skin and driving them with a sinusoidal frequency, it is shown that this control technique can be practically implemented in a lightweight, energy efficient way. Imperial-NUS Joint Ph.D. Programme.

  15. Dynamic flow control strategies of vehicle SCR Urea Dosing System

    Science.gov (United States)

    Lin, Wei; Zhang, Youtong; Asif, Malik

    2015-03-01

    Selective Catalyst Reduction(SCR) Urea Dosing System(UDS) directly affects the system accuracy and the dynamic response performance of a vehicle. However, the UDS dynamic response is hard to keep up with the changes of the engine's operating conditions. That will lead to low NO X conversion efficiency or NH3 slip. In order to optimize the injection accuracy and the response speed of the UDS in dynamic conditions, an advanced control strategy based on an air-assisted volumetric UDS is presented. It covers the methods of flow compensation and switching working conditions. The strategy is authenticated on an UDS and tested in different dynamic conditions. The result shows that the control strategy discussed results in higher dynamic accuracy and faster dynamic response speed of UDS. The inject deviation range is improved from being between -8% and 10% to -4% and 2% and became more stable than before, and the dynamic response time was shortened from 200 ms to 150 ms. The ETC cycle result shows that after using the new strategy the NH3 emission is reduced by 60%, and the NO X emission remains almost unchanged. The trade-off between NO X conversion efficiency and NH3 slip is mitigated. The studied flow compensation and switching working conditions can improve the dynamic performance of the UDS significantly and make the UDS dynamic response keep up with the changes of the engine's operating conditions quickly.

  16. Microcomputer-controlled flow meter used on a water loop

    International Nuclear Information System (INIS)

    Haniger, L.

    1982-01-01

    The report describes a microcomputer-controlled instrument intended for operational measurement on an experimental water loop. On the basis of pressure and temperature input signals the instrument calculates the specific weight, and for ten operator-selectable measuring channels it calculates the mass flow G(kp/s), or the voluminal flow Q(m 3 /h). On pressing the appropriate push-buttons the built-in display indicates the values of pressure (p) and temperature (t), as well as the values of specific weight γ calculated therefrom. For ten individually selectable channels the instrument displays either the values of the pressure differences of the measuring throttling elements (√Δpsub(i)), or the values of Gsub(i) or Qsub(i) as obtained by calculation. In addition, on pressing the Σ-push-button it summarizes the values of Gsub(i) and Qsub(i) for the selected channels. The device is controlled by an 8085 microprocessor, the analog unit MP 6812 being used as the A/D convertor. The instrument algorithm indicates some possible errors which may concern faults of input signals or mistakes in calculation. (author)

  17. Provably correct control flow graphs from Java bytecode programs with exceptions

    NARCIS (Netherlands)

    Amighi, A.; de Carvalho Gomes, Pedro; Gurov, Dilian; Huisman, Marieke

    2016-01-01

    We present an algorithm for extracting control flow graphs from Java bytecode that captures normal as well as exceptional control flow. We prove its correctness, in the sense that the behaviour of the extracted control flow graph is a sound over-approximation of the behaviour of the original

  18. End-tidal control vs. manually controlled minimal-flow anesthesia: a prospective comparative trial.

    Science.gov (United States)

    Wetz, A J; Mueller, M M; Walliser, K; Foest, C; Wand, S; Brandes, I F; Waeschle, R M; Bauer, M

    2017-11-01

    To ensure safe general anesthesia, manually controlled anesthesia requires constant monitoring and numerous manual adjustments of the gas dosage, especially for low- and minimal-flow anesthesia. Oxygen flow-rate and administration of volatile anesthetics can also be controlled automatically by anesthesia machines using the end-tidal control technique, which ensures constant end-tidal concentrations of oxygen and anesthetic gas via feedback and continuous adjustment mechanisms. We investigated the hypothesis that end-tidal control is superior to manually controlled minimal-flow anesthesia (0.5 l/min). In this prospective trial, we included 64 patients undergoing elective surgery under general anesthesia. We analyzed the precision of maintenance of the sevoflurane concentration (1.2-1.4%) and expiratory oxygen (35-40%) and the number of necessary adjustments. Target-concentrations of sevoflurane and oxygen were maintained at more stable levels with the use of end-tidal control (during the first 15 min 28% vs. 51% and from 15 to 60 min 1% vs. 19% deviation from sevoflurane target, P tidal oxygen (5, IQR 3-6). The target-concentrations were reached earlier with the use of end-tidal compared with manual controlled minimal-flow anesthesia but required slightly greater use of anesthetic agents (6.9 vs. 6.0 ml/h). End-tidal control is a superior technique for setting and maintaining oxygen and anesthetic gas concentrations in a stable and rapid manner compared with manual control. Consequently, end-tidal control can effectively support the anesthetist. © 2017 The Acta Anaesthesiologica Scandinavica Foundation. Published by John Wiley & Sons Ltd.

  19. Minnowbrook VI: 2009 Workshop on Flow Physics and Control for Internal and External Aerodynamics

    Science.gov (United States)

    LaGraff, John E.; Povinelli, Louis A.; Gostelow, J. Paul; Glauser, Mark

    2010-01-01

    Topics covered include: Flow Physics and control for Internal and External Aerodynamics (not in TOC...starts on pg13); Breaking CFD Bottlenecks in Gas-Turbine Flow-Path Design; Streamwise Vortices on the Convex Surfaces of Circular Cylinders and Turbomachinery Blading; DNS and Embedded DNS as Tools for Investigating Unsteady Heat Transfer Phenomena in Turbines; Cavitation, Flow Structure and Turbulence in the Tip Region of a Rotor Blade; Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows; Active Flow Control of Lifting Surface With Flap-Current Activities and Future Directions; Closed-Loop Control of Vortex Formation in Separated Flows; Global Instability on Laminar Separation Bubbles-Revisited; Very Large-Scale Motions in Smooth and Rough Wall Boundary Layers; Instability of a Supersonic Boundary-Layer With Localized Roughness; Active Control of Open Cavities; Amplitude Scaling of Active Separation Control; U.S. Air Force Research Laboratory's Need for Flow Physics and Control With Applications Involving Aero-Optics and Weapon Bay Cavities; Some Issues Related to Integrating Active Flow Control With Flight Control; Active Flow Control Strategies Using Surface Pressure Measurements; Reduction of Unsteady Forcing in a Vaned, Contra-Rotating Transonic Turbine Configuration; Active Flow Control Stator With Coanda Surface; Controlling Separation in Turbomachines; Flow Control on Low-Pressure Turbine Airfoils Using Vortex Generator Jets; Reduced Order Modeling Incompressible Flows; Study and Control of Flow Past Disk, and Circular and Rectangular Cylinders Aligned in the Flow; Periodic Forcing of a Turbulent Axisymmetric Wake; Control of Vortex Breakdown in Critical Swirl Regime Using Azimuthal Forcing; External and Turbomachinery Flow Control Working Group; Boundary Layers, Transitions and Separation; Efficiency Considerations in Low Pressure Turbines; Summary of Conference; and Final Plenary Session

  20. Power flow analysis for islanded microgrid in hierarchical structure of control system using optimal control theory

    Directory of Open Access Journals (Sweden)

    Thang Diep Thanh

    2017-12-01

    Full Text Available In environmental uncertainties, the power flow problem in islanded microgrid (MG becomes complex and non-trivial. The optimal power flow (OPL problem is described in this paper by using the energy balance between the power generation and load demand. The paper also presents the hierarchical control structure which consists of primary, secondary, tertiary, and emergency controls. Clearly, optimal power flow (OPL which implements a distributed tertiary control in hierarchical control. MG consists of diesel engine generator (DEG, wind turbine generator (WTG, and photovoltaic (PV power. In the control system considered, operation planning is realized based on profiles such that the MG, load, wind and photovoltaic power must be forecasted in short-period, meanwhile the dispatch source (i.e., DEG needs to be scheduled. The aim of the control problem is to find the dispatch output power by minimizing the total cost of energy that leads to the Hamilton-Jacobi-Bellman equation. Experimental results are presented, showing the effectiveness of optimal control such that the generation allows demand profile.

  1. Backbone of complex networks of corporations: The flow of control

    Science.gov (United States)

    Glattfelder, J. B.; Battiston, S.

    2009-09-01

    We present a methodology to extract the backbone of complex networks based on the weight and direction of links, as well as on nontopological properties of nodes. We show how the methodology can be applied in general to networks in which mass or energy is flowing along the links. In particular, the procedure enables us to address important questions in economics, namely, how control and wealth are structured and concentrated across national markets. We report on the first cross-country investigation of ownership networks, focusing on the stock markets of 48 countries around the world. On the one hand, our analysis confirms results expected on the basis of the literature on corporate control, namely, that in Anglo-Saxon countries control tends to be dispersed among numerous shareholders. On the other hand, it also reveals that in the same countries, control is found to be highly concentrated at the global level, namely, lying in the hands of very few important shareholders. Interestingly, the exact opposite is observed for European countries. These results have previously not been reported as they are not observable without the kind of network analysis developed here.

  2. Dielectric barrier discharge plasma actuator for flow control

    Science.gov (United States)

    Opaits, Dmitry Florievich

    Electrohydrodynamic (EHD) and magnetohydrodynamic phenomena are being widely studied for aerodynamic applications. The major effects of these phenomena are heating of the gas, body force generation, and enthalpy addition or extraction, [1, 2, 3]. In particular, asymmetric dielectric barrier discharge (DBD) plasma actuators are known to be effective EHD device in aerodynamic control, [4, 5]. Experiments have demonstrated their effectiveness in separation control, acoustic noise reduction, and other aeronautic applications. In contrast to conventional DBD actuators driven by sinusoidal voltages, we proposed and used a voltage profile consisting of nanosecond pulses superimposed on dc bias voltage. This produces what is essentially a non-self-sustained discharge: the plasma is generated by repetitive short pulses, and the pushing of the gas occurs primarily due to the bias voltage. The advantage of this non-self-sustained discharge is that the parameters of ionizing pulses and the driving bias voltage can be varied independently, which adds flexibility to control and optimization of the actuators performance. Experimental studies were conducted of a flow induced in a quiescent room air by a single DBD actuator. A new approach for non-intrusive diagnostics of plasma actuator induced flows in quiescent gas was proposed, consisting of three elements coupled together: the Schlieren technique, burst mode of plasma actuator operation, and 2-D numerical fluid modeling. During the experiments, it was found that DBD performance is severely limited by surface charge accumulation on the dielectric. Several ways to mitigate the surface charge were found: using a reversing DC bias potential, three-electrode configuration, slightly conductive dielectrics, and semi conductive coatings. Force balance measurements proved the effectiveness of the suggested configurations and advantages of the new voltage profile (pulses+bias) over the traditional sinusoidal one at relatively low

  3. Flow Diode and Method for Controlling Fluid Flow Origin of the Invention

    Science.gov (United States)

    Dyson, Rodger W (Inventor)

    2015-01-01

    A flow diode configured to permit fluid flow in a first direction while preventing fluid flow in a second direction opposite the first direction is disclosed. The flow diode prevents fluid flow without use of mechanical closures or moving parts. The flow diode utilizes a bypass flowline whereby all fluid flow in the second direction moves into the bypass flowline having a plurality of tortuous portions providing high fluidic resistance. The portions decrease in diameter such that debris in the fluid is trapped. As fluid only travels in one direction through the portions, the debris remains trapped in the portions.

  4. Dynamic evolution process of turbulent channel flow after opposition control

    Energy Technology Data Exchange (ETDEWEB)

    Ge, Mingwei; Tian, De; Yongqian, Liu, E-mail: gmwncepu@163.com [State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources (North China Electric Power University), Beijing102206 (China)

    2017-02-15

    Dynamic evolution of turbulent channel flow after application of opposition control (OC), together with the mechanism of drag reduction, is studied through direct numerical simulation (DNS). In the simulation, the pressure gradient is kept constant, and the flow rate increases due to drag reduction. In the transport of mean kinetic energy (MKE), one part of the energy from the external pressure is dissipated by the mean shear, and the other part is transported to the turbulent kinetic energy (TKE) through a TKE production term (TKP). It is found that the increase of MKE is mainly induced by the reduction of TKP that is directly affected by OC. Further analysis shows that the suppression of the redistribution term of TKE in the wall normal direction plays a key role in drag reduction, which represses the wall normal velocity fluctuation and then reduces TKP through the attenuation of its main production term. When OC is suddenly applied, an acute imbalance of energy in space is induced by the wall blowing and suction. Both the skin-friction and TKP terms exhibit a transient growth in the initial phase of OC, which can be attributed to the local effect of 〈 v ′ v ′〉 and 〈− u ′ v ′〉 in the viscous sublayer. (paper)

  5. Parallel Vortex Body Interaction Enabled by Active Flow Control

    Science.gov (United States)

    Weingaertner, Andre; Tewes, Philipp; Little, Jesse

    2017-11-01

    An experimental study was conducted to explore the flow physics of parallel vortex body interaction between two NACA 0012 airfoils. Experiments were carried out at chord Reynolds numbers of 740,000. Initially, the leading airfoil was characterized without the target one being installed. Results are in good agreement with thin airfoil theory and data provided in the literature. Afterward, the leading airfoil was fixed at 18° incidence and the target airfoil was installed 6 chord lengths downstream. Plasma actuation (ns-DBD), originating close to the leading edge, was used to control vortex shedding from the leading airfoil at various frequencies (0.04 governing parameters of this vortex body interaction are explored. This work was supported by the Army Research Office under ARO Grant No. W911NF-14-1-0662.

  6. Chaos control for the plates subjected to subsonic flow

    Science.gov (United States)

    Norouzi, Hamed; Younesian, Davood

    2016-07-01

    The suppression of chaotic motion in viscoelastic plates driven by external subsonic air flow is studied. Nonlinear oscillation of the plate is modeled by the von-Kármán plate theory. The fluid-solid interaction is taken into account. Galerkin's approach is employed to transform the partial differential equations of the system into the time domain. The corresponding homoclinic orbits of the unperturbed Hamiltonian system are obtained. In order to study the chaotic behavior of the plate, Melnikov's integral is analytically applied and the threshold of the excitation amplitude and frequency for the occurrence of chaos is presented. It is found that adding a parametric perturbation to the system in terms of an excitation with the same frequency of the external force can lead to eliminate chaos. Variations of the Lyapunov exponent and bifurcation diagrams are provided to analyze the chaotic and periodic responses. Two perturbation-based control strategies are proposed. In the first scenario, the amplitude of control forces reads a constant value that should be precisely determined. In the second strategy, this amplitude can be proportional to the deflection of the plate. The performance of each controller is investigated and it is found that the second scenario would be more efficient.

  7. Unsteady Flows Control Hydrologic Turnover Rates in Antarctic Hyporheic Zones

    Science.gov (United States)

    Wlostowski, A. N.; Gooseff, M. N.; McKnight, D. M.; Lyons, W. B.; Saelens, E.

    2016-12-01

    Hydrologic turnover of the hyporheic zone (HZ) is the process of HZ flowpaths receiving water and solutes from the stream channel while simultaneously contributing water and solutes from the HZ back to the stream channel. The influence of hydrologic turnover on HZ solute storage depends on the relative magnitude of hyporheic exchange rates (i.e. physical transport) and biogeochemical reaction rates. Because both exchange rates and reaction rates are unsteady in natural systems, the availability of solutes in the HZ is controlled by the legacy of hydraulic and biological conditions. In this study, we quantify the influence of unsteady flows on hydrologic turnover of the HZ. We study a glacial melt stream in the McMurdo Dry Valleys of Antarctica (MDVs). The MDVs provide an ideal setting for investigating hydrologic and chemical storage characteristics of HZs, because nearly all streamflow is generated from glacier melt and the HZ is vertically bounded by continuous permafrost. A dense network of shallow groundwater wells and piezometers was installed along a 60-meter reach of Von Guerard Stream. 12 days of continuous water level data in each well was used to compute the magnitude and direction of 2D hydraulic gradients between the stream channel and lateral hyporheic aquifer. Piezometers were sampled daily for stable isotope abundances. The direction and magnitude of the cross-valley (CV), perpendicular to the thalweg, component of hydraulic gradients is sensitive to daily flood events and exhibits significant spatial heterogeneity. CV gradients are consistently oriented from the hyporheic aquifer towards the stream channel on 2 sections of the study reach, whereas CV gradients are consistently oriented from the stream channel towards the hyporheic aquifer on 1 section. Three sections show diel changes in orientation of CV gradients, coincident with the passage of daily flood events. During a 4-day period of low flows, the HZ is isotopically distinct from the stream

  8. The friction control of magnetic fluid in the Couette flow

    Energy Technology Data Exchange (ETDEWEB)

    Labkovich, O.N., E-mail: olji@tut.by; Reks, A.G.; Chernobai, V.A.

    2017-06-01

    In the work characteristic areas of magnetic fluid flow are experimentally determined in the gap between the cylinders: the area of strong dipole-dipole interaction between magnetite particles 0flow 8flow Ta>41,2. For areas with high flow losses in viscous friction is shown the possibility of reducing the introduction of magnetic fluid of carbon nanotubes and creating a rotating magnetic field. - Highlights: • Typical areas of magnetic fluid flow are determined in the gap. • Influence of dipole-dipole interaction of magnetite particles on the viscous friction. • Features of Taylor vortex flow.

  9. Provably Correct Control-Flow Graphs from Java Programs with Exceptions

    NARCIS (Netherlands)

    Amighi, A.; de Carvalho Gomes, Pedro; Huisman, Marieke

    2011-01-01

    We present an algorithm to extract flow graphs from Java bytecode, focusing on exceptional control flows. We prove its correctness, meaning that the behaviour of the extracted control-flow graph is an over-approximation of the behaviour of the original program. Thus any safety property that holds

  10. Experimental Studies of Low-Pressure Turbine Flows and Flow Control. Streamwise Pressure Profiles and Velocity Profiles

    Science.gov (United States)

    Volino, Ralph

    2012-01-01

    This report summarizes research performed in support of the NASA Glenn Research Center (GRC) Low-Pressure Turbine (LPT) Flow Physics Program. The work was performed experimentally at the U.S. Naval Academy faculties. The geometry corresponded to "Pak B" LPT airfoil. The test section simulated LPT flow in a passage. Three experimental studies were performed: (a) Boundary layer measurements for ten baseline cases under high and low freestream turbulence conditions at five Reynolds numbers of 25,000, 50,000, 100,000, 200,000, and 300,000, based on passage exit velocity and suction surface wetted length; (b) Passive flow control studies with three thicknesses of two-dimensional bars, and two heights of three-dimensional circular cylinders with different spanwise separations, at same flow conditions as the 10 baseline cases; (c) Active flow control with oscillating synthetic (zero net mass flow) vortex generator jets, for one case with low freestream turbulence and a low Reynolds number of 25,000. The Passive flow control was successful at controlling the separation problem at low Reynolds numbers, with varying degrees of success from case to case and varying levels of impact at higher Reynolds numbers. The active flow control successfully eliminated the large separation problem for the low Reynolds number case. Very detailed data was acquired using hot-wire anemometry, including single and two velocity components, integral boundary layer quantities, turbulence statistics and spectra, turbulent shear stresses and their spectra, and intermittency, documenting transition, separation and reattachment. Models were constructed to correlate the results. The report includes a summary of the work performed and reprints of the publications describing the various studies.This report summarizes research performed in support of the NASA Glenn Research Center (GRC) Low-Pressure Turbine (LPT) Flow Physics Program. The work was performed experimentally at the U.S. Naval Academy

  11. Insights from field observations into controls on flow front speed in submarine sediment flows

    Science.gov (United States)

    Heerema, C.; Talling, P.; Cartigny, M.; Paull, C. K.; Gwiazda, R.; Clare, M. A.; Parsons, D. R.; Xu, J.; Simmons, S.; Maier, K. L.; Chapplow, N.; Gales, J. A.; McGann, M.; Barry, J.; Lundsten, E. M.; Anderson, K.; O'Reilly, T. C.; Rosenberger, K. J.; Sumner, E. J.; Stacey, C.

    2017-12-01

    Seafloor avalanches of sediment called turbidity currents are one of the most important processes for moving sediment across our planet. Only rivers carry comparable amounts of sediment across such large areas. Here we present some of the first detailed monitoring of these underwater flows that is being undertaken at a series of test sites. We seek to understand the factors that determine flow front speed, and how that speed varies with distance. This frontal speed is particularly important for predicting flow runout, and how the power of these hazardous flows varies with distance. First, we consider unusually detailed measurements of flow front speed defined by transit times between moorings and other tracked objects placed on the floor of Monterey Canyon offshore California in 2016-17. These measurements are then compared to flow front speeds measured using multiple moorings in Bute Inlet, British Columbia in 2016; and by cable breaks in Gaoping Canyon offshore Taiwan in 2006 and 2009. We seek to understand how flow front velocity is related to seafloor gradient, flow front thickness and density. It appears that the spatial evolution of frontal speed is similar in multiple flows, although their peak frontal velocities vary. Flow front velocity tends to increase rapidly initially before declining rather gradually over tens or even hundreds of kilometres. It has been proposed that submarine flows will exist in one of two states; either eroding and accelerating, or depositing sediment and dissipating. We conclude by discussing the implications of this global compilation of flow front velocities for understanding submarine flow behaviour.

  12. Controlling flow conditions of test filters in iodine filters

    International Nuclear Information System (INIS)

    Holmberg, R.; Laine, J.

    1979-03-01

    Several different iodine filter and test filter designs and experience gained from their operation are presented. For the flow experiments, an iodine filter system equipped with flow regulating and measuring devices was built. In the experiments the influence of the packing method of the iodine sorption material and the influence of the flow regulating and measuring divices upon the flow conditions in the test filters was studied. On the basis of the experiments it has been shown that the flows through the test filters always can be adjusted to a correct value if there only is a high enough pressure difference available across the test filter ducting. As a result of the research, several different methods are presented with which the flows through the test filters in both operating and future iodine sorption system can easily be measured and adjusted to their correct values. (author)

  13. Optimal control of algae growth by controlling CO 2 and nutrition flow using Pontryagin Maximum Principle

    Science.gov (United States)

    Mardlijah; Jamil, Ahmad; Hanafi, Lukman; Sanjaya, Suharmadi

    2017-09-01

    There are so many benefit of algae. One of them is using for renewable energy and sustainable in the future. The greater growth of algae will increasing biodiesel production and the increase of algae growth is influenced by glucose, nutrients and photosynthesis process. In this paper, the optimal control problem of the growth of algae is discussed. The objective function is to maximize the concentration of dry algae while the control is the flow of carbon dioxide and the nutrition. The solution is obtained by applying the Pontryagin Maximum Principle. and the result show that the concentration of algae increased more than 15 %.

  14. Effect of plasma actuator control parameters on a transitional flow

    Science.gov (United States)

    Das Gupta, Arnob; Roy, Subrata

    2018-04-01

    This study uses a wall-resolved implicit large eddy simulation to investigate the effects of different surface dielectric barrier discharge actuator parameters such as the geometry of the electrodes, frequency, amplitude of actuation and thermal effect. The actuator is used as a tripping device on a zero-pressure gradient laminar boundary layer flow. It is shown that the standard linear actuator creates structures like the Tollmien-Schlichting wave transition. The circular serpentine, square serpentine and spanwise actuators have subharmonic sinuous streak breakdown and behave like oblique wave transition scenario. The spanwise and square actuators cause comparably faster transition to turbulence. The square actuator adds energy into the higher spanwise wavenumber modes resulting in a faster transition compared to the circular actuator. When the Strouhal number of actuation is varied, the transition does not occur for a value below 0.292. Higher frequencies with same amplitude of actuation lead to faster transition. Small changes (<4%) in the amplitude of actuation can have a significant impact on the transition location which suggests that an optimal combination of frequency and amplitude exists for highest control authority. The thermal bumps approximating the actuator heating only shows localized effects on the later stages of transition for temperatures up to 373 K and can be ignored for standard actuators operating in subsonic regimes.

  15. Recycling flow rate control device in BWR type reactor

    International Nuclear Information System (INIS)

    Fujiwara, Tadashi; Koda, Yasushi

    1988-01-01

    Purpose: To reduce the recycling pump speed if the pressure variation width and the variation ratio in the nuclear reactor exceed predetermined values, to thereby avoid the shutdown of the plant. Constitution: There has been proposed a method of monitoring the neutron flux increase thereby avoiding unnecessary plant shutdown, but it involves a problems of reactor scram depending on the state of the plant and the set values. In view of the above, in the plant using internal pumps put under the thyristor control and having high response to recycling flow rate, the reactor pressure is monitored and the speed of the internal pump is rapidly reduced when the pressure variation width and variation ratio exceed predetermined values to reduce the reactor power and avoid the plant shutdown. This can reduce the possibility of unnecessary power reduction due to neutron flux noises or the possibility of plant shutdown under low power conditions. Further, since the reactor operation can be continued without stopping the recycling pump, the operation upon recovery can be made rapid. (Horiuchi, T.)

  16. Power flow controller with a fractionally rated back-to-back converter

    Science.gov (United States)

    Divan, Deepakraj M.; Kandula, Rajendra Prasad; Prasai, Anish

    2016-03-08

    A power flow controller with a fractionally rated back-to-back (BTB) converter is provided. The power flow controller provide dynamic control of both active and reactive power of a power system. The power flow controller inserts a voltage with controllable magnitude and phase between two AC sources at the same frequency; thereby effecting control of active and reactive power flows between the two AC sources. A transformer may be augmented with a fractionally rated bi-directional Back to Back (BTB) converter. The fractionally rated BTB converter comprises a transformer side converter (TSC), a direct-current (DC) link, and a line side converter (LSC). By controlling the switches of the BTB converter, the effective phase angle between the two AC source voltages may be regulated, and the amplitude of the voltage inserted by the power flow controller may be adjusted with respect to the AC source voltages.

  17. Active bypass flow control for a seal in a gas turbine engine

    Science.gov (United States)

    Ebert, Todd A.; Kimmel, Keith D.

    2017-01-10

    An active bypass flow control system for controlling bypass compressed air based upon leakage flow of compressed air flowing past an outer balance seal between a stator and rotor of a first stage of a gas turbine in a gas turbine engine is disclosed. The active bypass flow control system is an adjustable system in which one or more metering devices may be used to control the flow of bypass compressed air as the flow of compressed air past the outer balance seal changes over time as the outer balance seal between the rim cavity and the cooling cavity wears. In at least one embodiment, the metering device may include a valve formed from one or more pins movable between open and closed positions in which the one pin at least partially bisects the bypass channel to regulate flow.

  18. Structural Control and Groundwater Flow in the Nubian Aquifer

    Science.gov (United States)

    Fathy, K.; Sultan, M.; Ahmed, M.; Save, H.; Emil, M. K.; Elkaliouby, B.

    2017-12-01

    An integrated research approach (remote sensing, field, geophysics) was conducted to investigate the structural control on groundwater flow in large aquifers using the less studied Nubian Sandstone Aquifer System (NSAS) of NE Africa as a test site. The aquifer extends over 2.2 x 106 km2 in Egypt, Libya, Chad, and Sudan and consists of thick (> 3 kms), water-bearing, Paleozoic and Mesozoic sandstone with intercalations of Tertiary shale and clay. It is subdivided into three sub-basins (Northern Sudan Platform [NSP], Dakhla [DAS], and Kufra) that are separated by basement uplifts (e.g., E-W trending Uweinat-Aswan uplift that separates DAS from the NSP). Aquifer recharge occurs in the south (NSP and southern Kufra) where the aquifer is unconfined and precipitation is high (Average Annual Precipitation [AAP]: 117 mm/yr.) and discharge is concentrated in the north (DAS and northern Kufra). Our approach is a three-fold exercise. Firstly, we compared GOCE-based Global Geopotential Models (GGMs) to terrestrial gravity anomalies for 21262 sites to select the optimum model for deriving Bouguer gravity anomalies. Secondly, structures and uplifts were mapped using hill shade images and their extension in the subsurface were mapped using the Eigen_6C4 model-derived Bouguer anomalies and their Tilt Derivative products (TDR). Thirdly, hydrological analysis was conducted using GRACE CSR 1° x 1° mascon solutions to investigate the mass variations in relation to the mapped structures. Our findings include: (1) The Eigen-6C4 is the optimum model having the lowest deviation (9.122 mGal) from the terrestrial gravity anomalies; (2) the surface expressions of structures matched fairly well with their postulated extensions in the subsurface; (3) identified fault systems include: Red Sea rift-related N-S to NW-SE trending grabens formed by reactivating basement structures during Red Sea opening and Syrian arc-related NE-SW trending dextral shear systems; (4) TWS patterns are uniform

  19. Computational Modeling of Flow Control Systems for Aerospace Vehicles, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — Clear Science Corp. proposes to develop computational methods for designing active flow control systems on aerospace vehicles with the primary objective of...

  20. Flow Physics and Control for Internal and External Aerodynamics

    Science.gov (United States)

    Wygnanski, I.

    2010-01-01

    Exploiting instabilities rather than forcing the flow is advantageous. Simple 2D concepts may not always work. Nonlinear effects may result in first order effect. Interaction between spanwise and streamwise vortices may have a paramount effect on the mean flow, but this interaction may not always be beneficial.

  1. Controllability of Non-Newtonian Fluids Under Homogeneous Flows

    National Research Council Canada - National Science Library

    Wilson, Lynda M

    2007-01-01

    .... The constitutive models are as follows: the Phan-Thien-Tanner model; the Johnson-Segalman model; and the Doi model. The effect of extensional flow on these models and the effect of shear flow on the Doi model have not been explored previous to this work...

  2. PI2 controller based coordinated control with Redox Flow Battery and Unified Power Flow Controller for improved Restoration Indices in a deregulated power system

    Directory of Open Access Journals (Sweden)

    R. Thirunavukarasu

    2016-12-01

    Full Text Available The nature of power system restoration problem involves status assessment, optimization of generation capability and load pickup. This paper proposes the evaluation of Power System Restoration Indices (PSRI based on the Automatic Generation Control (AGC assessment of interconnected power system in a deregulated environment. The PSRI are useful for system planners to prepare the power system restoration plans and to improve the efficiency of the physical operation of the power system with the increased transmission capacity in the network. The stabilization of frequency and tie-line power oscillations in an interconnected power system becomes challenging when implemented in the future competitive environment. This paper also deals with the concept of AGC in two-area reheat power system having coordinated control action with Redox Flow Battery (RFB and Unified Power Flow Controller (UPFC are capable of controlling the network performance in a very fast manner and improve power transfer limits in order to have a better restoration. In addition to that a new Proportional–Double Integral (PI2 controller is designed and implemented in AGC loop and controller parameters are optimized through Bacterial Foraging Optimization (BFO algorithm. Simulation results reveal that the proposed PI2 controller is that it has good stability during load variations, excellent transient and dynamic responses when compared with the system comprising PI controller. Moreover the AGC loop with RFB coordinated with UPFC has greatly improved the dynamic response and it reduces the control input requirements, to ensure improved PSRI in order to provide the reduced restoration time, thereby improving the system reliability.

  3. Estimating drain flow from measured water table depth in layered soils under free and controlled drainage

    Science.gov (United States)

    Saadat, Samaneh; Bowling, Laura; Frankenberger, Jane; Kladivko, Eileen

    2018-01-01

    Long records of continuous drain flow are important for quantifying annual and seasonal changes in the subsurface drainage flow from drained agricultural land. Missing data due to equipment malfunction and other challenges have limited conclusions that can be made about annual flow and thus nutrient loads from field studies, including assessments of the effect of controlled drainage. Water table depth data may be available during gaps in flow data, providing a basis for filling missing drain flow data; therefore, the overall goal of this study was to examine the potential to estimate drain flow using water table observations. The objectives were to evaluate how the shape of the relationship between drain flow and water table height above drain varies depending on the soil hydraulic conductivity profile, to quantify how well the Hooghoudt equation represented the water table-drain flow relationship in five years of measured data at the Davis Purdue Agricultural Center (DPAC), and to determine the impact of controlled drainage on drain flow using the filled dataset. The shape of the drain flow-water table height relationship was found to depend on the selected hydraulic conductivity profile. Estimated drain flow using the Hooghoudt equation with measured water table height for both free draining and controlled periods compared well to observed flow with Nash-Sutcliffe Efficiency values above 0.7 and 0.8 for calibration and validation periods, respectively. Using this method, together with linear regression for the remaining gaps, a long-term drain flow record for a controlled drainage experiment at the DPAC was used to evaluate the impacts of controlled drainage on drain flow. In the controlled drainage sites, annual flow was 14-49% lower than free drainage.

  4. Flujo de control en iOS Flow control in iOS

    Directory of Open Access Journals (Sweden)

    Franklin Hernández Castro

    2012-11-01

    Full Text Available El objetivo de este artículo es explicar los flujos de control que se usan en la programación de las aplicaciones en iOS, con el fin de resumir los aspectos más relevantes que se deben tomar en cuenta para programar una tarea a ser realizada por un dispositivo móvil del tipo iPhone o iPad. Debido a que el ambiente iOS es estrictamente orientado a objetos (OOP, los flujos de control no son obvios; además, los estándares de la firma Apple® definen patrones de diseño en el sistema que son altamente recomendados en este tipo de diseño. En este artículo se introducen algunos de ellos.This paper explain the control flows that are used by programming applications in iOS, trying to summarize the most important aspects to be considered by programming mobile devices like iPhone and iPad. Because iOS environment, is strictly a object-oriented one(OOP, control flows are not obvious, besides Apple® use design patterns highly recommended in this type of programming. Here we introduces some of them.

  5. Controlling Subsurface Fractures and Fluid Flow: A Basic Research Agenda

    Energy Technology Data Exchange (ETDEWEB)

    Pyrak-Nolte, Laura J [Purdue Univ., West Lafayette, IN (United States); DePaolo, Donald J. [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Univ. of California, Berkeley, CA (United States); Pietraß, Tanja [USDOE Office of Science, Washington, DC (United States)

    2015-05-22

    From beneath the surface of the earth, we currently obtain about 80-percent of the energy our nation consumes each year. In the future we have the potential to generate billions of watts of electrical power from clean, green, geothermal energy sources. Our planet’s subsurface can also serve as a reservoir for storing energy produced from intermittent sources such as wind and solar, and it could provide safe, long-term storage of excess carbon dioxide, energy waste products and other hazardous materials. However, it is impossible to underestimate the complexities of the subsurface world. These complexities challenge our ability to acquire the scientific knowledge needed for the efficient and safe exploitation of its resources. To more effectively harness subsurface resources while mitigating the impacts of developing and using these resources, the U.S. Department of Energy established SubTER – the Subsurface Technology and Engineering RD&D Crosscut team. This DOE multi-office team engaged scientists and engineers from the national laboratories to assess and make recommendations for improving energy-related subsurface engineering. The SubTER team produced a plan with the overall objective of “adaptive control of subsurface fractures and fluid flow.”This plan revolved around four core technological pillars—Intelligent Wellbore Systems that sustain the integrity of the wellbore environment; Subsurface Stress and Induced Seismicity programs that guide and optimize sustainable energy strategies while reducing the risks associated with subsurface injections; Permeability Manipulation studies that improve methods of enhancing, impeding and eliminating fluid flow; and New Subsurface Signals that transform our ability to see into and characterize subsurface systems. The SubTER team developed an extensive R&D plan for advancing technologies within these four core pillars and also identified several areas where new technologies would require additional basic research

  6. Investigation of co-flow jet flow control and its applications

    Science.gov (United States)

    Lefebvre, Alexis M.

    This thesis investigates the performance of co-flow jet (CFJ) flow control and its applications using experimental testing and computational fluid dynamics (CFD) simulations. For a stationary airfoil and wing, CFJ increases the lift coefficient (CL), reduces the drag and may produce thrust at a low angle of attack (AoA). The maximum lift coefficient is substantially increased for a 2D CFJ airfoil and reaches a value of 4.8 at Cmicro = 0.30. The power consumption of the CFJ pump, measured by the power coefficient (Pc), is influenced by a variety of parameters, including the momentum coefficient (C micro ), the AoA, the injection slot location, and the internal cavity configuration. A low Cmicro of 0.04 produces a rather small Pc in the range of 0.01--0.02 while a higher Cmicro rapidly increases the Pc. Due to the stronger leading edge suction effect, increasing the AoA decreases the Pc. That is until the flow is near separation, within about 2°--3° of the stall AoA. An injection slot location within 2%--5% chord from the leading edge very effectively reduces the power coefficient. An internal cavity design with no separation is crucial to minimize the CFJ power consumption. Overall, the CFJ effectiveness is enhanced with an increasing Mach number as long as the flow remains subsonic, typically with free stream Mach number less than 0.4. Two pitching airfoil oscillations with dynamic stall are studied in this thesis, namely the mild dynamic stall and the deep dynamic stall. At Mach 0.3, the CFJ with a relatively low Cmicro of 0.08 removes the mild dynamic stall. Thereby, the time-averaged lift is increased by 32% and the time-averaged drag is decreased by 80%. The resulting time-averaged aerodynamic (L/D)ave, which does not take the pumping power into account, reaches 118.3. When C micro is increased, the time-averaged drag becomes negative, which demonstrates the feasibility of a CFJ to propel helicopter blades using its pump as the only source of power. The deep

  7. Frequency tuning allows flow direction control in microfluidic networks with passive features.

    Science.gov (United States)

    Jain, Rahil; Lutz, Barry

    2017-05-02

    Frequency tuning has emerged as an attractive alternative to conventional pumping techniques in microfluidics. Oscillating (AC) flow driven through a passive valve can be rectified to create steady (DC) flow, and tuning the excitation frequency to the characteristic (resonance) frequency of the underlying microfluidic network allows control of flow magnitude using simple hardware, such as an on-chip piezo buzzer. In this paper, we report that frequency tuning can also be used to control the direction (forward or backward) of the rectified DC flow in a single device. Initially, we observed that certain devices provided DC flow in the "forward" direction expected from previous work with a similar valve geometry, and the maximum DC flow occurred at the same frequency as a prominent peak in the AC flow magnitude, as expected. However, devices of a slightly different geometry provided the DC flow in the opposite direction and at a frequency well below the peak AC flow. Using an equivalent electrical circuit model, we found that the "forward" DC flow occurred at the series resonance frequency (with large AC flow peak), while the "backward" DC flow occurred at a less obvious parallel resonance (a valley in AC flow magnitude). We also observed that the DC flow occurred only when there was a measurable differential in the AC flow magnitude across the valve, and the DC flow direction was from the channel with large AC flow magnitude to that with small AC flow magnitude. Using these observations and the AC flow predictions from the equivalent circuit model, we designed a device with an AC flowrate frequency profile that was expected to allow the DC flow in opposite directions at two distinct frequencies. The fabricated device showed the expected flow reversal at the expected frequencies. This approach expands the flow control toolkit to include both magnitude and direction control in frequency-tuned microfluidic pumps. The work also raises interesting questions about the

  8. A congestion line flow control in deregulated power system

    Directory of Open Access Journals (Sweden)

    Venkatarajan Shanmuga Sundaram

    2011-01-01

    Full Text Available Under open access, market-driven transactions have become the new independent decision variables defining the behavior of the power system. The possibility of transmission lines getting over-loaded is relatively more under deregulated operation because different parts of the system are owned by separate companies and in part operated under varying service charges. This paper discusses a two-tier algorithm for correcting the lone overloads in conjunction with the conventional power-flow methods. The method uses line flow sensitivities, which are computed by the East Decoupled Power-flow algorithm and can be adapted for on-line implementation.

  9. Numerical Studies of a Supersonic Fluidic Diverter Actuator for Flow Control

    Science.gov (United States)

    Gokoglu, Suleyman A.; Kuczmarski, Maria A.; Culley, Dennis e.; Raghu, Surya

    2010-01-01

    The analysis of the internal flow structure and performance of a specific fluidic diverter actuator, previously studied by time-dependent numerical computations for subsonic flow, is extended to include operation with supersonic actuator exit velocities. The understanding will aid in the development of fluidic diverters with minimum pressure losses and advanced designs of flow control actuators. The self-induced oscillatory behavior of the flow is successfully predicted and the calculated oscillation frequencies with respect to flow rate have excellent agreement with our experimental measurements. The oscillation frequency increases with Mach number, but its dependence on flow rate changes from subsonic to transonic to supersonic regimes. The delay time for the initiation of oscillations depends on the flow rate and the acoustic speed in the gaseous medium for subsonic flow, but is unaffected by the flow rate for supersonic conditions

  10. Power flow control strategy in distribution network for dc type distributed energy resource at load bus

    International Nuclear Information System (INIS)

    Hanif, A.; Choudhry, M.A.

    2013-01-01

    This research work presents a feed forward power flow control strategy in the secondary distribution network working in parallel with a DC type distributed energy resource (DER) unit with SPWM-IGBT Voltage Source Converter (VSC). The developed control strategy enables the VSC to be used as power flow controller at the load bus in the presence of utility supply. Due to the investigated control strategy, power flow control from distributed energy resource (DER) to common load bus is such that power flows to the load without facing any power quality problem. The technique has an added advantage of controlling power flow without having a dedicated power flow controller. The SPWM-IGBT VSC is serving the purpose of dc-ac converter as well as power flow controller. Simulations for a test system using proposed power flow control strategy are carried out using SimPower Systems toolbox of MATLAB at the rate and Simulink at the rate. The results show that a reliable, effective and efficient operation of DC type DER unit in coordination with main utility network can be achieved. (author)

  11. Flow rate control systems for coolants for BWR type reactors

    International Nuclear Information System (INIS)

    Igarashi, Yoko; Kato, Naoyoshi.

    1981-01-01

    Purpose: To increase spontaneous recycling flow rate of coolants in BWR type reactors when the water level in the reactor decreases, by communicating a downcomer with a lower plenum. Constitution: An opening is provided to the back plate disposed at the lower end of a reactor core shroud for communicating a downcomer with a lower plenum, and an ON-OFF valve actuated by an operation rod is provided to the opening. When abnormal water level or pressure in the reactor is detected by a level metal or pressure meter, the operation rod is driven to open the ON-OFF valve, whereby coolants fed from a jet pump partially flows through the opening to increase the spontaneous recycling flow rate of the coolants. This can increase the spontaneous recycling flow rate of the coolants upon spontaneous recycling operation, thereby maintaining the reactor safety and the fuel soundness. (Moriyama, K.)

  12. Electro-Magnetic Flow Control to Enable Natural Laminar Flow Wings

    Data.gov (United States)

    National Aeronautics and Space Administration — This research team has developed a solid-state electromagnetic device that, when embedded along the leading edge of an aircraft wing, can disrupt laminar air flow on...

  13. Active bypass flow control for a seal in a gas turbine engine

    Science.gov (United States)

    Ebert, Todd A.; Kimmel, Keith D.

    2017-03-14

    An active bypass flow control system for controlling bypass compressed air based upon leakage flow of compressed air flowing past an outer balance seal between a stator and rotor of a first stage of a gas turbine in a gas turbine engine is disclosed. The active bypass flow control system is an adjustable system in which one or more metering devices may be used to control the flow of bypass compressed air as the flow of compressed air past the outer balance seal changes over time as the outer balance seal between the rim cavity and the cooling cavity wears In at least one embodiment, the metering device may include an annular ring having at least one metering orifice extending therethrough, whereby alignment of the metering orifice with the outlet may be adjustable to change a cross-sectional area of an opening of aligned portions of the outlet and the metering orifice.

  14. Effect Of Steel Flow Control Devices On Flow And Temperature Field In The Tundish Of Continuous Casting Machine

    Directory of Open Access Journals (Sweden)

    Sowa L.

    2015-06-01

    Full Text Available The mathematical model and numerical simulations of the liquid steel flow in a tundish are presented in this paper. The problem was treated as a complex and solved by the finite element method. One takes into consideration in the mathematical model the changes of thermophysical parameters depending on the temperature. The single-strand tundish is used to casting slabs. The internal work space of the tundish was modified by flow control devices. The first device was a pour pad situated in the pouring tundish zone. The second device was a dam. The third device was a baffle with three holes. The dam and baffle were placed in the tundish at different positions depending on the variant. The main purpose of using these was to put barriers in the steel flow path as well as give directional metal flow upwards which facilitated inclusion floatation. The interaction of flow control devices on hydrodynamic conditions was received from numerical simulations. As a result of the computations carried out, the liquid steel flow and steel temperature fields were obtained. The influences of the tundish modifications on the velocity fields in liquid phase of the steel were estimated, because these have essential an influence on high-quality of a continuous steel cast slab.

  15. An iterative method for controlling reactive power flow in boundary transformers

    Energy Technology Data Exchange (ETDEWEB)

    Trigo, Angel L.; Martinez, Jose L.; Riquelme, Jesus; Romero, Esther [Department of Electrical Engineering, University of Seville (Spain)

    2011-02-15

    This paper presents an operational tool designed to help the system operator to control the reactive power flow in transmission-subtransmission boundary transformers. The main objective is to determine the minimum number of control actions necessary to ensure that reactive power flows in transmission/subtransmission transformers remain within limits. The proposed iterative procedure combines the use of a linear programming problem and a load flow tool. The linear programming assumes a linear behaviour between dependent and control variables around an operating point, modelled with sensitivities. Experimental results regarding IEEE systems are provided comparing the performance of the proposed approach with that of a conventional optimal power flow. (author)

  16. Scenarios for control and data flows in multiprotocol over ATM

    Science.gov (United States)

    Kujoory, Ali

    1997-10-01

    The multiprotocol over ATM (MPOA), specified by the ATM Forum, provides an architecture for transfer of Internetwork layer packets (Layer 3 datagram such as IP, IPX) over ATM subnets or across the emulated LANs. MPOA provides shortcuts that bypass routers to avoid router bottlenecks. It is a grand union of some of the existing standards such as LANE by the ATM Forum, NHRP by the IETF, and the Q.2931 by ITU. The intent of this paper is to clarify the data flows between pairs of source and destination hosts in an MPOA system. It includes scenarios for both the intra- and inter-subnet flows between different pairs of MPOA end-systems. The intrasubnet flows simply use LANE for address resolution or data transfer. The inter-subnet flows may use a default path for short-lived flows or a shortcut for long-lived flows. The default path uses the LANE and router capabilities. The shortcut path uses LANE plus NHRP for ATM address resoluton. An ATM virtual circuit is established before the data transfer. This allows efficient transfer of internetwork layer packets over ATM for real-time applications.

  17. A Computed River Flow-Based Turbine Controller on a Programmable Logic Controller for Run-Off River Hydroelectric Systems

    Directory of Open Access Journals (Sweden)

    Razali Jidin

    2017-10-01

    Full Text Available The main feature of a run-off river hydroelectric system is a small size intake pond that overspills when river flow is more than turbines’ intake. As river flow fluctuates, a large proportion of the potential energy is wasted due to the spillages which can occur when turbines are operated manually. Manual operation is often adopted due to unreliability of water level-based controllers at many remote and unmanned run-off river hydropower plants. In order to overcome these issues, this paper proposes a novel method by developing a controller that derives turbine output set points from computed mass flow rate of rivers that feed the hydroelectric system. The computed flow is derived by summation of pond volume difference with numerical integration of both turbine discharge flows and spillages. This approach of estimating river flow allows the use of existing sensors rather than requiring the installation of new ones. All computations, including the numerical integration, have been realized as ladder logics on a programmable logic controller. The implemented controller manages the dynamic changes in the flow rate of the river better than the old point-level based controller, with the aid of a newly installed water level sensor. The computed mass flow rate of the river also allows the controller to straightforwardly determine the number of turbines to be in service with considerations of turbine efficiencies and auxiliary power conservation.

  18. Flow Control Research at NASA Langley in Support of High-Lift Augmentation

    Science.gov (United States)

    Sellers, William L., III; Jones, Gregory S.; Moore, Mark D.

    2002-01-01

    The paper describes the efforts at NASA Langley to apply active and passive flow control techniques for improved high-lift systems, and advanced vehicle concepts utilizing powered high-lift techniques. The development of simplified high-lift systems utilizing active flow control is shown to provide significant weight and drag reduction benefits based on system studies. Active flow control that focuses on separation, and the development of advanced circulation control wings (CCW) utilizing unsteady excitation techniques will be discussed. The advanced CCW airfoils can provide multifunctional controls throughout the flight envelope. Computational and experimental data are shown to illustrate the benefits and issues with implementation of the technology.

  19. Control of Nonlinear Coupled Electromagnetic Actuators for Active Drag Reduction in Turbulent Flow

    OpenAIRE

    Seidler, Florian; Trabert, Julius; Dück, Marcel; van Waasen, Stefan; Schiek, Michael; Abel, Dirk; Castelan, E. B.

    2016-01-01

    The research group FOR1779 “active drag reduction via wavy surface oscillations” develops robust methods for reduction of turbulent friction drag by flow control. The planned concentration on unsteady flow conditions requires a control of the electromagnetic actuator system for generation of transversal surface waves. The bars are positioned in parallel and coupled with an aluminum surface to generate a travelling wave perpendicular to the flow field. The actuator system can be approximately ...

  20. Flow-Control Systems Proof of Concept for Snowmelt Runoff at McMurdo Station, Antarctica

    Science.gov (United States)

    2017-01-01

    ER D C/ CR RE L TR -1 7- 1 Engineering for Polar Operations , Logistics, and Research (EPOLAR) Flow-Control Systems Proof of Concept for...January 2017 Flow-Control Systems Proof of Concept for Snowmelt Runoff at McMurdo Station, Antarctica Rosa Affleck U.S. Army Engineer Research and...runoff can be extreme where the flow can overwhelm both the drainage system and the operations and maintenance (O&M) crew. CRREL has been involved

  1. Enhancement of Arterial Pressure Pulsatility by Controlling Continuous-Flow Left Ventricular Assist Device Flow Rate in Mock Circulatory System.

    Science.gov (United States)

    Bozkurt, Selim; van de Vosse, Frans N; Rutten, Marcel C M

    Continuous-flow left ventricular assist devices (CF-LVADs) generally operate at a constant speed, which reduces pulsatility in the arteries and may lead to complications such as functional changes in the vascular system, gastrointestinal bleeding, or both. The purpose of this study is to increase the arterial pulse pressure and pulsatility by controlling the CF-LVAD flow rate. A MicroMed DeBakey pump was used as the CF-LVAD. A model simulating the flow rate through the aortic valve was used as a reference model to drive the pump. A mock circulation containing two synchronized servomotor-operated piston pumps acting as left and right ventricles was used as a circulatory system. Proportional-integral control was used as the control method. First, the CF-LVAD was operated at a constant speed. With pulsatile-speed CF-LVAD assistance, the pump was driven such that the same mean pump output was generated. Continuous and pulsatile-speed CF-LVAD assistance provided the same mean arterial pressure and flow rate, while the index of pulsatility increased significantly for both arterial pressure and pump flow rate signals under pulsatile speed pump support. This study shows the possibility of improving the pulsatility of CF-LVAD support by regulating pump speed over a cardiac cycle without reducing the overall level of support.

  2. AC field effect flow control of EOF in complex microfluidic systems with integrated electrodes

    NARCIS (Netherlands)

    van der Wouden, E.J.; Pennathur, S.; van den Berg, Albert; Locascio, L.E.; Gaitan, M.; Paegel, B.M.; Ross, D.J.; Vreeland, W.N.

    2008-01-01

    In this work, we demonstrate that positive net flow can be induced and controlled with relatively low potential due to the parallel alignment of the integrated channel electrodes. Therefore, we present a novel method to exquisitely control Electro Osmotic Flow (EOF) by using integrated electrodes

  3. Routing power flows in distribution networks using locally controlled power electronics

    NARCIS (Netherlands)

    Hamelink, J.; Nguyen, P.H.; Kling, W.L.; Ribeiro, P.F.; Groot, de R.J.W.

    2012-01-01

    The power grid has gradually changed its operation during the recent decades. These developments have encouraged a shift from centralized to decentralized power flow control. A research has been carried out to investigate the possibilities to control power flows using the Smart Power Router (SPR) in

  4. Inter-eNB Flow Control for Heterogeneous Networks with Dual Connectivity

    DEFF Research Database (Denmark)

    Wang, Hua; Rosa, Claudio; Pedersen, Klaus I.

    2015-01-01

    the gain provided by DC, an efficient flow control of data between the involved macro and small cell eNBs is proposed. It is demonstrated how proper configuration of the proposed flow control algorithm offers efficient trade-offs between reducing the probability that one of the eNBs involved in the DC runs...

  5. Field effect control of electro-osmotic flow in microfluidic networks

    NARCIS (Netherlands)

    van der Wouden, E.J.

    2006-01-01

    This thesis describes the development of a Field Effect Flow Control (FEFC) system for the control of Electro Osmotic Flow (EOF) in microfluidic networks. For this several aspects of FEFC have been reviewed and a process to fabricate microfluidic channels with integrated electrodes has been

  6. Control-flow analysis of function calls and returns by abstract interpretation

    DEFF Research Database (Denmark)

    Midtgaard, Jan; Jensen, Thomas P.

    2012-01-01

    Abstract interpretation techniques are used to derive a control-flow analysis for a simple higher-order functional language. The analysis approximates the interprocedural control-flow of both function calls and returns in the presence of first-class functions and tail-call optimization. In additi...... a rational reconstruction of a constraint-based CFA from abstract interpretation principles....

  7. Controlling mixing and segregation in time periodic granular flows

    Science.gov (United States)

    Bhattacharya, Tathagata

    Segregation is a major problem for many solids processing industries. Differences in particle size or density can lead to flow-induced segregation. In the present work, we employ the discrete element method (DEM)---one type of particle dynamics (PD) technique---to investigate the mixing and segregation of granular material in some prototypical solid handling devices, such as a rotating drum and chute. In DEM, one calculates the trajectories of individual particles based on Newton's laws of motion by employing suitable contact force models and a collision detection algorithm. Recently, it has been suggested that segregation in particle mixers can be thwarted if the particle flow is inverted at a rate above a critical forcing frequency. Further, it has been hypothesized that, for a rotating drum, the effectiveness of this technique can be linked to the probability distribution of the number of times a particle passes through the flowing layer per rotation of the drum. In the first portion of this work, various configurations of solid mixers are numerically and experimentally studied to investigate the conditions for improved mixing in light of these hypotheses. Besides rotating drums, many studies of granular flow have focused on gravity driven chute flows owing to its practical importance in granular transportation and to the fact that the relative simplicity of this type of flow allows for development and testing of new theories. In this part of the work, we observe the deposition behavior of both mono-sized and polydisperse dry granular materials in an inclined chute flow. The effects of different parameters such as chute angle, particle size, falling height and charge amount on the mass fraction distribution of granular materials after deposition are investigated. The simulation results obtained using DEM are compared with the experimental findings and a high degree of agreement is observed. Tuning of the underlying contact force parameters allows the achievement

  8. Using artificial intelligence to control fluid flow computations

    Science.gov (United States)

    Gelsey, Andrew

    1992-01-01

    Computational simulation is an essential tool for the prediction of fluid flow. Many powerful simulation programs exist today. However, using these programs to reliably analyze fluid flow and other physical situations requires considerable human effort and expertise to set up a simulation, determine whether the output makes sense, and repeatedly run the simulation with different inputs until a satisfactory result is achieved. Automating this process is not only of considerable practical importance but will also significantly advance basic artificial intelligence (AI) research in reasoning about the physical world.

  9. Use of integrity control and automatic start of reserve in a multi-channel temperature and flow rate control device

    International Nuclear Information System (INIS)

    Strzalkowski, L.

    1975-01-01

    A way to increase reliability of process quantity control is control of the integrity of the control plants themselves. The possibilities of integrity control on control devices having simply duplicated control channels or working on the basis of the ''two-from-three'' principle are valued. A highly reliable integrity control is possible by use of test signals. For an appropriate control device, structure and function of the assemblies are described. The integrity control device may be used in the water coolant temperature and flow rate control system for all technological channels of the research reactor ''Maria''

  10. Microprocessor Based Temperature Control of Liquid Delivery with Flow Disturbances.

    Science.gov (United States)

    Kaya, Azmi

    1982-01-01

    Discusses analytical design and experimental verification of a PID control value for a temperature controlled liquid delivery system, demonstrating that the analytical design techniques can be experimentally verified by using digital controls as a tool. Digital control instrumentation and implementation are also demonstrated and documented for…

  11. Recent advances in extensional rheology: controlled flows and fracture

    DEFF Research Database (Denmark)

    Hassager, Ole; Huang, Qian

    Extensional deformation and flow occur in a number of polymer processing operations such as fiber spinning and film blowing. To understand and analyze material behavior in such operations, accurate and quantitative measurements of the rheological properties in well-defined extensional deformation...

  12. A Simple CPS Transformation of Control-Flow Information

    DEFF Research Database (Denmark)

    Damian, Daniel; Danvy, Olivier

    2002-01-01

    We build on Danvy and Nielsen's first-order program transformation into continuation-passing style (CPS) to design a new CPS transformation of flow information that is simpler and more efficient than what has been presented in previous work. The key to simplicity and efficiency is that our CPS tr...

  13. Discretionary Information Flow Control for Interaction-Oriented Specifications

    DEFF Research Database (Denmark)

    Lluch Lafuente, Alberto; Nielson, Flemming; Nielson, Hanne Riis

    2015-01-01

    system for statically checking if a system specification ensures an information flow policy. The approach is illustrated with two archetypal examples of distributed and parallel computing systems: a protocol for an identity-secured data providing service and a parallel MapReduce computation....

  14. Controlling two-phase flow in microfluidic systems using electrowetting

    NARCIS (Netherlands)

    Gu, H.

    2011-01-01

    Electrowetting (EW)-based digital microfluidic systems (DMF) and droplet-based two-phase flow microfluidic systems (TPF) with closed channels are the most widely used microfluidic platforms. In general, these two approaches have been considered independently. However, integrating the two

  15. Neurophysiological Basis of Cerebral Blood Flow Control: An ...

    African Journals Online (AJOL)

    The book describes the current understanding of cerebral blood flow ... metaoolism of the central nervous system. The brain ... in stroke it is a deficiency of the book that the clinical correlates are .... Review of Nutrition and Dietetics. Edited by ...

  16. Control algorithm for multiscale flow simulations of water

    DEFF Research Database (Denmark)

    Kotsalis, E. M.; Walther, Jens Honore; Kaxiras, E.

    2009-01-01

    We present a multiscale algorithm to couple atomistic water models with continuum incompressible flow simulations via a Schwarz domain decomposition approach. The coupling introduces an inhomogeneity in the description of the atomistic domain and prevents the use of periodic boundary conditions...

  17. Electromagnetic control of oscillating flows in a cavity

    NARCIS (Netherlands)

    Kalter, R.

    2015-01-01

    In continuous steel casting, liquid steel flows turbulently through a submerged nozzle into a thin, vertical mould. In the mould the liquid steel is cooled, such that it solidifies and plate steel is formed. On top of the liquid steel in the mould, a slag layer is present and due to the turbulent

  18. Controlled generation and use of CO in flow

    DEFF Research Database (Denmark)

    Hansen, Steffen V. F.; Wilson, Zoe E.; Ulven, Trond

    2016-01-01

    A method for the generation and use of carbon monoxide in flow chemistry has been developed. By using a tube-in-tube reactor, oxalyl chloride can be conveniently and safely hydrolyzed using a NaOH solution to generate CO in the outer stream, which then passes through AF-2400 semi-permeable inner...

  19. Flow control by combining radial pulsation and rotation of a cylinder in uniform flow

    Science.gov (United States)

    Oualli, H.; Hanchi, S.; Bouabdallah, A.; Gad-El-Hak, M.

    2008-11-01

    Flow visualizations and hot-wire measurements are carried out to study a circular cylinder undergoing simultaneous radial pulsation and rotation and placed in a uniform flow. The Reynolds number is in the range of 1,000--22,000, for which transition in the shear layers and near wake is expected. Our previous experimental and numerical investigations in this subcritical flow regime have established the existence of an important energy transfer mechanism from the mean flow to the fluctuations. Radial pulsations cause and enhance that energy transfer. Certain values of the amplitude and frequency of the pulsations lead to negative drag (i.e. thrust). The nonlinear interaction between the Magnus effect induced by the steady rotation of the cylinder and the near-wake modulated by the bluff body's pulsation leads to alteration of the omnipresent Kármán vortices and the possibility of optimizing the lift-to-drag ratio as well as the rates of heat and mass transfer. Other useful applications include the ability to enhance or suppress the turbulence intensity, and to avoid the potentially destructive lock-in phenomenon in the wake of bridges, electric cables and other structures.

  20. Engineering analysis of mass flow rate for turbine system control and design

    International Nuclear Information System (INIS)

    Yoo, Yong H.; Suh, Kune Y.

    2011-01-01

    Highlights: → A computer code is written to predict the steam mass flow rate through valves. → A test device is built to study the steam flow characteristics in the control valve. → Mass flow based methodology eases the programming and experimental procedures. → The methodology helps express the characteristics of each device of a turbine system. → The results can commercially be used for design and operation of the turbine system. - Abstract: The mass flow rate is determined in the steam turbine system by the area formed between the stem disk and the seat of the control valve. For precise control the steam mass flow rate should be known given the stem lift. However, since the thermal hydraulic characteristics of steam coming from the generator or boiler are changed going through each device, it is hard to accurately predict the steam mass flow rate. Thus, to precisely determine the steam mass flow rate, a methodology and theory are developed in designing the turbine system manufactured for the nuclear and fossil power plants. From the steam generator or boiler to the first bunch of turbine blades, the steam passes by a stop valve, a control valve and the first nozzle, each of which is connected with piping. The corresponding steam mass flow rate can ultimately be computed if the thermal and hydraulic conditions are defined at the stop valve, control valve and pipes. The steam properties at the inlet of each device are changed at its outlet due to geometry. The Compressed Adiabatic Massflow Analysis (CAMA) computer code is written to predict the steam mass flow rate through valves. The Valve Engineered Layout Operation (VELO) test device is built to experimentally study the flow characteristics of steam flowing inside the control valve with the CAMA input data. The Widows' Creek type control valve was selected as reference. CAMA is expected to be commercially utilized to accurately design and operate the turbine system for fossil as well as nuclear power

  1. Numerical Investigation of Flow Control Feasibility with a Trailing Edge Flap

    DEFF Research Database (Denmark)

    Zhu, Wei Jun; Shen, Wen Zhong; Sørensen, Jens Nørkær

    2014-01-01

    the control system, a standard PID controller is implemented in a finite volume based incompressible flow solver. An immersed boundary method is applied to treat the problem of simulating a deformable airfoil trailing edge. The flow field is solved using a 2D Reynolds averaged Navier-Stokes finite volume...... solver. In order to more accurately simulate wall bounded flows around the immersed boundary, a modified boundary condition is introduced in the k- ω turbulence model. As an example, turbulent flow over a NACA 64418 airfoil with a deformable trailing edge is investigated. Results from numerical...

  2. Modeling generalized interline power-flow controller (GIPFC using 48-pulse voltage source converters

    Directory of Open Access Journals (Sweden)

    Amir Ghorbani

    2018-05-01

    Full Text Available Generalized interline power-flow controller (GIPFC is one of the voltage-source controller (VSC-based flexible AC transmission system (FACTS controllers that can independently regulate the power-flow over each transmission line of a multiline system. This paper presents the modeling and performance analysis of GIPFC based on 48-pulsed voltage-source converters. This paper deals with a cascaded multilevel converter model, which is a 48-pulse (three levels voltage source converter. The voltage source converter described in this paper is a harmonic neutralized, 48-pulse GTO converter. The GIPFC controller is based on d-q orthogonal coordinates. The algorithm is verified using simulations in MATLAB/Simulink environment. Comparisons between unified power flow controller (UPFC and GIPFC are also included. Keywords: Generalized interline power-flow controller (GIPFC, Voltage source converter (VCS, 48-pulse GTO converter

  3. Controlling hydrophilicity of polymer film by altering gas flow rate in atmospheric-pressure homogeneous plasma

    International Nuclear Information System (INIS)

    Kang, Woo Seok; Hur, Min; Lee, Jae-Ok; Song, Young-Hoon

    2014-01-01

    Graphical abstract: - Highlights: • Controlling hydrophilicity of polymer film by varying gas flow rate is proposed in atmospheric-pressure homogeneous plasma treatment. • Without employing additional reactive gas, requiring more plasma power and longer treatment time, hydrophilicity of polyimide films was improved after the low-gas-flow plasma treatment. • The gas flow rate affects the hydrophilic properties of polymer surface by changing the discharge atmosphere in the particular geometry of the reactor developed. • Low-gas-flow induced wettability control suggests effective and economical plasma treatment. - Abstract: This paper reports on controlling the hydrophilicity of polyimide films using atmospheric-pressure homogeneous plasmas by changing only the gas flow rate. The gas flow changed the discharge atmosphere by mixing the feed gas with ambient air because of the particular geometry of the reactor developed for the study, and a low gas flow rate was found to be favorable because it generated abundant nitrogen or oxygen species that served as sources of hydrophilic functional groups over the polymer surface. After low-gas-flow plasma treatment, the polymer surface exhibited hydrophilic characteristics with increased surface roughness and enhanced chemical properties owing to the surface addition of functional groups. Without adding any reactive gases or requiring high plasma power and longer treatment time, the developed reactor with low-gas-flow operation offered effective and economical wettability control of polyimide films

  4. Implementation of Real-Time Feedback Flow Control Algorithms on a Canonical Testbed

    Science.gov (United States)

    Tian, Ye; Song, Qi; Cattafesta, Louis

    2005-01-01

    This report summarizes the activities on "Implementation of Real-Time Feedback Flow Control Algorithms on a Canonical Testbed." The work summarized consists primarily of two parts. The first part summarizes our previous work and the extensions to adaptive ID and control algorithms. The second part concentrates on the validation of adaptive algorithms by applying them to a vibration beam test bed. Extensions to flow control problems are discussed.

  5. AGC of a multi-area power system under deregulated environment using redox flow batteries and interline power flow controller

    Directory of Open Access Journals (Sweden)

    Tulasichandra Sekhar Gorripotu

    2015-12-01

    Full Text Available In this paper, Proportional Integral Derivative with Filter (PIDF is proposed for Automatic Generation Control (AGC of a multi-area power system in deregulated environment. Initially, a two area four units thermal system without any physical constraints is considered and the gains of the PIDF controller are optimized employing Differential Evolution (DE algorithm using ITAE criterion. The superiority of proposed DE optimized PIDF controller over Fuzzy Logic controller is demonstrated. Then, to further improve the system performance, an Interline Power Flow Controller (IPFC is placed in the tie-line and Redox Flow Batteries (RFB is considered in the first area and the controller parameters are tuned. Additionally, to get an accurate insight of the AGC problem, important physical constraints such as Time Delay (TD and Generation Rate Constraints (GRC are considered and the controller parameters are retuned. The performance of proposed controller is evaluated under different operating conditions that take place in a deregulated power market. Further, the proposed approach is extended to a two area six units hydro thermal system. Finally, sensitivity analysis is performed by varying the system parameters and operating load conditions from their nominal values.

  6. Development of linear flow rate control system for eccentric butter-fly valve

    International Nuclear Information System (INIS)

    Kwak, K. K.; Cho, S. W.; Park, J. S.; Cho, J. H.; Song, I. T.; Kim, J. G.; Kwon, S. J.; Kim, I. J.; Park, W. K.

    1999-12-01

    Butter-fly valves are advantageous over gate, globe, plug, and ball valves in a variety of installations, particularly in the large sizes. The purpose of this project development of linear flow rate control system for eccentric butter-fly valve (intelligent butter-fly valve system). The intelligent butter-fly valve system consist of a valve body, micro controller. The micro controller consist of torque control system, pressure censor, worm and worm gear and communication line etc. The characteristics of intelligent butter-fly valve system as follows: Linear flow rate control function. Digital remote control function. guard function. Self-checking function. (author)

  7. Analysis and control of supersonic vortex breakdown flows

    Science.gov (United States)

    Kandil, Osama A.

    1990-01-01

    Analysis and computation of steady, compressible, quasi-axisymmetric flow of an isolated, slender vortex are considered. The compressible, Navier-Stokes equations are reduced to a simpler set by using the slenderness and quasi-axisymmetry assumptions. The resulting set along with a compatibility equation are transformed from the diverging physical domain to a rectangular computational domain. Solving for a compatible set of initial profiles and specifying a compatible set of boundary conditions, the equations are solved using a type-differencing scheme. Vortex breakdown locations are detected by the failure of the scheme to converge. Computational examples include isolated vortex flows at different Mach numbers, external axial-pressure gradients and swirl ratios.

  8. Controlling chaos in a fluid flow past a movable cylinder

    International Nuclear Information System (INIS)

    Vallejo, Juan C.; Marino, Ines P.; Sanjuan, Miguel A.F.; Kurths, Juergen

    2003-01-01

    The model of a two-dimensional fluid flow past a cylinder is a relatively simple problem with a strong impact in many applied fields, such as aerodynamics or chemical sciences, although most of the involved physical mechanisms are not yet well known. This paper analyzes the fluid flow past a cylinder in a laminar regime with Reynolds number, Re, around 200, where two vortices appear behind the cylinder, by using an appropriate time-dependent stream function and applying non-linear dynamics techniques. The goal of the paper is to analyze under which circumstances the chaoticity in the wake of the cylinder might be modified, or even suppressed. And this has been achieved with the help of some indicators of the complexity of the trajectories for the cases of a rotating cylinder and an oscillating cylinder

  9. Heat transfer enhancement through control of added perturbation velocity in flow field

    International Nuclear Information System (INIS)

    Wang, Jiansheng; Wu, Cui; Li, Kangning

    2013-01-01

    Highlights: ► Three strategies which restrain the flow drag in heat transfer are proposed. ► Added perturbation induces quasi-streamwise vortices around controlled zone. ► The flow and heat transfer features depend on induced quasi-streamwise vortices. ► Vertical strategy has the best synthesis performance of three control strategies. ► Synthesis performance with control strategy is superior to that without strategy. - Abstract: The characteristics of heat transfer and flow, through an added perturbation velocity, in a rectangle channel, are investigated by Large Eddy Simulation (LES). The downstream, vertical, and upstream control strategy, which can suppress the lift of low speed streaks in the process of improving the performance of heat transfer, are adopted in numerical investigation. Taking both heat transfer and flow properties into consideration, the synthesis performance of heat transfer and flow of three control strategies are evaluated. The numerical results show that the flow structure in boundary layer has been varied obviously for the effect of perturbation velocity and induced quasi-streamwise vortices emerging around the controlled zone. The results indicate that the vertical control strategy has the best synthesis performance of the three control strategies, which also has the least skin frication coefficient. The upstream and downstream strategies can improve the heat transfer performance, but the skin frication coefficient is higher than that with vertical control strategy

  10. Zonal flow dynamics and control of turbulent transport in stellarators.

    Science.gov (United States)

    Xanthopoulos, P; Mischchenko, A; Helander, P; Sugama, H; Watanabe, T-H

    2011-12-09

    The relation between magnetic geometry and the level of ion-temperature-gradient (ITG) driven turbulence in stellarators is explored through gyrokinetic theory and direct linear and nonlinear simulations. It is found that the ITG radial heat flux is sensitive to details of the magnetic configuration that can be understood in terms of the linear behavior of zonal flows. The results throw light on the question of how the optimization of neoclassical confinement is related to the reduction of turbulence.

  11. Feedback control for unsteady flow and its application to the stochastic Burgers equation

    Science.gov (United States)

    Choi, Haecheon; Temam, Roger; Moin, Parviz; Kim, John

    1993-01-01

    The study applies mathematical methods of control theory to the problem of control of fluid flow with the long-range objective of developing effective methods for the control of turbulent flows. Model problems are employed through the formalism and language of control theory to present the procedure of how to cast the problem of controlling turbulence into a problem in optimal control theory. Methods of calculus of variations through the adjoint state and gradient algorithms are used to present a suboptimal control and feedback procedure for stationary and time-dependent problems. Two types of controls are investigated: distributed and boundary controls. Several cases of both controls are numerically simulated to investigate the performances of the control algorithm. Most cases considered show significant reductions of the costs to be minimized. The dependence of the control algorithm on the time-descretization method is discussed.

  12. Distributed flow sensing for closed-loop speed control of a flexible fish robot.

    Science.gov (United States)

    Zhang, Feitian; Lagor, Francis D; Yeo, Derrick; Washington, Patrick; Paley, Derek A

    2015-10-23

    Flexibility plays an important role in fish behavior by enabling high maneuverability for predator avoidance and swimming in turbulent flow. This paper presents a novel flexible fish robot equipped with distributed pressure sensors for flow sensing. The body of the robot is molded from soft, hyperelastic material, which provides flexibility. Its Joukowski-foil shape is conducive to modeling the fluid analytically. A quasi-steady potential-flow model is adopted for real-time flow estimation, whereas a discrete-time vortex-shedding flow model is used for higher-fidelity simulation. The dynamics for the flexible fish robot yield a reduced model for one-dimensional swimming. A recursive Bayesian filter assimilates pressure measurements to estimate flow speed, angle of attack, and foil camber. The closed-loop speed-control strategy combines an inverse-mapping feedforward controller based on an average model derived for periodic actuation of angle-of-attack and a proportional-integral feedback controller utilizing the estimated flow information. Simulation and experimental results are presented to show the effectiveness of the estimation and control strategy. The paper provides a systematic approach to distributed flow sensing for closed-loop speed control of a flexible fish robot by regulating the flapping amplitude.

  13. Development of an Active Flow Control Technique for an Airplane High-Lift Configuration

    Science.gov (United States)

    Shmilovich, Arvin; Yadlin, Yoram; Dickey, Eric D.; Hartwich, Peter M.; Khodadoust, Abdi

    2017-01-01

    This study focuses on Active Flow Control methods used in conjunction with airplane high-lift systems. The project is motivated by the simplified high-lift system, which offers enhanced airplane performance compared to conventional high-lift systems. Computational simulations are used to guide the implementation of preferred flow control methods, which require a fluidic supply. It is first demonstrated that flow control applied to a high-lift configuration that consists of simple hinge flaps is capable of attaining the performance of the conventional high-lift counterpart. A set of flow control techniques has been subsequently considered to identify promising candidates, where the central requirement is that the mass flow for actuation has to be within available resources onboard. The flow control methods are based on constant blowing, fluidic oscillators, and traverse actuation. The simulations indicate that the traverse actuation offers a substantial reduction in required mass flow, and it is especially effective when the frequency of actuation is consistent with the characteristic time scale of the flow.

  14. Developed generalised unified power flow controller model in the Newton–Raphson power-flow analysis using combined mismatches method

    DEFF Research Database (Denmark)

    Kamel, Salah; Jurado, Francisco; Chen, Zhe

    2016-01-01

    values are calculated during the iterative process based on the desired controlled values and buses voltage at the terminals of GUPFC. The parameters of GUPFC can be calculated during the iterative process and the final values are updated after load flow convergence. Using the developed GUPFC model......, the original structure and symmetry of the admittance and Jacobian matrices can still be kept, the changing of Jacobian matrix is eliminated. Consequently, the complexities of the computer load flow program codes with GUPFC are reduced. The HPCIM load flow code with the proposed model is written in C......++ programming language. Where, the SuperLU library is utilised to handle the sparse Jacobian matrix. The proposed model has been validated using the standard IEEE test systems....

  15. A new method for controlling refrigerant flow in automobile air conditioning

    Energy Technology Data Exchange (ETDEWEB)

    Xuquan Li; Jiangping Chen; Zhijiu Chen [Shanghai Jiao Tong University (China). Institute of Refrigeration and Cryogenics Engineering; Weihua Liu; Wei Hu; Xiaobing Liu [Shanghai Delphi Automotive Air Conditiong Systems Co. Ltd., Changhai (China)

    2004-05-01

    This paper describes the improvement of the refrigerant flow control method by using an electronic expansion valve (EEV) which is driven by a stepper motor in automobile air conditioning system. An EEV can make a quick response to the abrupt change in the refrigerant flow rate during the change in automobile speed and the thermostatic on/off operation. The flow rate characteristic of the EEV for automobile air conditioning was presented. A microcontroller is used to receive the input signal and generate the output signal to control the opening of the EEV. The fuzzy self-tuning proportional-integral-derivative (PID) control method is employed. Experimental results show that the new control method can feed adequate refrigerant flow into the evaporator in various operations. The evaporator discharge air temperature has dropped by approximately 3{sup o}C as compared with that of the conventional PID control system. (author)

  16. Field Effect Flow Control in a Polymer T-Intersection Microfluidic Network

    Science.gov (United States)

    Sniadecki, Nathan J.; Chang, Richard; Beamesderfer, Mike; Lee, Cheng S.; DeVoe, Don L.

    2003-01-01

    We present a study of induced pressure pumping in a polymer microchannel due to differential electroosmotic flow @OF) rates via field-effect flow control (FEFC). The experimental results demonstrate that the induced pressure pumping is dependent on the distance of the FEFC gate from the cathodic gate. A proposed flow model based on a linearly-decaying zeta potential profile is found to successfully predict experimental trends.

  17. A lattice hydrodynamic model based on delayed feedback control considering the effect of flow rate difference

    Science.gov (United States)

    Wang, Yunong; Cheng, Rongjun; Ge, Hongxia

    2017-08-01

    In this paper, a lattice hydrodynamic model is derived considering not only the effect of flow rate difference but also the delayed feedback control signal which including more comprehensive information. The control method is used to analyze the stability of the model. Furthermore, the critical condition for the linear steady traffic flow is deduced and the numerical simulation is carried out to investigate the advantage of the proposed model with and without the effect of flow rate difference and the control signal. The results are consistent with the theoretical analysis correspondingly.

  18. Computational Study of pH-sensitive Hydrogel-based Microfluidic Flow Controllers

    Science.gov (United States)

    Kurnia, Jundika C.; Birgersson, Erik; Mujumdar, Arun S.

    2011-01-01

    This computational study investigates the sensing and actuating behavior of a pH-sensitive hydrogel-based microfluidic flow controller. This hydrogel-based flow controller has inherent advantage in its unique stimuli-sensitive properties, removing the need for an external power supply. The predicted swelling behavior the hydrogel is validated with steady-state and transient experiments. We then demonstrate how the model is implemented to study the sensing and actuating behavior of hydrogels for different microfluidic flow channel/hydrogel configurations: e.g., for flow in a T-junction with single and multiple hydrogels. In short, the results suggest that the response of the hydrogel-based flow controller is slow. Therefore, two strategies to improve the response rate of the hydrogels are proposed and demonstrated. Finally, we highlight that the model can be extended to include other stimuli-responsive hydrogels such as thermo-, electric-, and glucose-sensitive hydrogels. PMID:24956303

  19. Characterization of Passive Flow-Actuated Microflaps Inspired by Shark Skin for Separation Control

    Science.gov (United States)

    Morris, Jackson; Devey, Sean; Lang, Amy; Hubner, Paul

    2017-11-01

    Thanks to millions of years of natural selection, sharks have evolved into quick apex predators. Previous research has proven shark skin to reduce flow separation, which would result in lower pressure drag. Mako shark skin is made up of microscopic scales on the order of 0.2 mm in size. These scales are hypothesized to be a flow control mechanism, capable of being passively actuated by reversed flow. We believe shark scales are strategically sized to interact with the lower 5 percent of the boundary layer, where reversed flow occurs near the wall. Previous wind tunnel research has shown that it is possible to passively actuate 2D flaps in the lower regions of the boundary layer. This research aims to identify reverse flow conditions that will cause small 3D flaps to actuate. Several sets of microflaps (about 4 mm in length) geometrically similar to shark scales were 3D printed. These microflaps were tested in a low-speed wind tunnel in various reverse flow conditions. Microflaps were observed to be actuated by the reversing flow and flow conditions were characterized using a hot-wire probe. These microflaps have the potential to mimic the mako shark type of flow control in air, passively actuated by reverse flow conditions. This research was supported by Boeing, the US Army, and the National Science Foundation REU program.

  20. Neural control of adrenal medullary and cortical blood flow during hemorrhage

    International Nuclear Information System (INIS)

    Breslow, M.J.; Jordan, D.A.; Thellman, S.T.; Traystman, R.J.

    1987-01-01

    Hemorrhagic hypotension produces an increase in adrenal medullary blood flow and a decrease in adrenal cortical blood flow. To determine whether changes in adrenal blood flow during hemorrhage are neurally mediated, the authors compared blood flow responses following adrenal denervation (splanchnic nerve section) with changes in the contralateral, neurally intact adrenal. Carbonized microspheres labeled with 153 Gd, 114 In, 113 Sn, 103 Ru, 95 Nb or 46 Se were used. Blood pressure was reduced and maintained at 60 mmHg for 25 min by hemorrhage into a pressurized bottle system. Adrenal cortical blood flow decreased to 50% of control with hemorrhage in both the intact and denervated adrenal. Adrenal medullary blood flow increased to four times control levels at 15 and 25 min posthemorrhage in the intact adrenal, but was reduced to 50% of control at 3, 5, and 10 min posthemorrhage in the denervated adrenal. In a separate group of dogs, the greater splanchnic nerve on one side was electrically stimulated at 2, 5, or 15 Hz for 40 min. Adrenal medullary blood flow increased 5- to 10-fold in the stimulated adrenal but was unchanged in the contralateral, nonstimulated adrenal. Adrenal cortical blood flow was not affected by nerve stimulation. They conclude that activity of the splanchnic nerve profoundly affects adrenal medullary vessels but not adrenal cortical vessels and mediates the observed increase in adrenal medullary blood flow during hemorrhagic hypotension

  1. Oscillations and chaos in renal blood flow control

    DEFF Research Database (Denmark)

    Holstein-Rathlou, N H

    1993-01-01

    In normotensive, halothane-anesthetized rats, oscillations can be found both in the single-nephron blood flow and in the tubular pressure. Experimental data and computer simulations support the hypothesis that the oscillations are caused by the tubuloglomerular feedback (TGF) mechanism. Model...... oscillations. The parameter range where model studies show instability overlaps with the physiologic range for the values of the same parameters. The system appears to be poised on the border between stability and oscillation, and a small parameter change may cause the system to move from one state...

  2. Precision flow-controlled rubidium-82 generator for bolus and constant infusion studies

    International Nuclear Information System (INIS)

    Yano, Y.

    1981-01-01

    A unique flow rate controller and large reservoir pumping system have been developed for infusing rubidium-82 intravenously at bolus, constant, or variable infusion rates. Using rubidium-82 and the positron ring detector tomograph, extraction or flow information can be obtained in studies of the heart, head, or kidneys

  3. Sound Control-Flow Graph Extraction for Java Programs with Exceptions

    NARCIS (Netherlands)

    Amighi, A.; de Carvalho Gomes, Pedro; Gurov, Dilian; Huisman, Marieke; Eleftherakis, George; Hinchey, Mike; Holcombe, Mike

    2012-01-01

    We present an algorithm to extract control-flow graphs from Java bytecode, considering exceptional flows. We then establish its correctness: the behavior of the extracted graphs is shown to be a sound over-approximation of the behavior of the original programs. Thus, any temporal safety property

  4. Development of advanced stability theory suction prediction techniques for laminar flow control. [on swept wings

    Science.gov (United States)

    Srokowski, A. J.

    1978-01-01

    The problem of obtaining accurate estimates of suction requirements on swept laminar flow control wings was discussed. A fast accurate computer code developed to predict suction requirements by integrating disturbance amplification rates was described. Assumptions and approximations used in the present computer code are examined in light of flow conditions on the swept wing which may limit their validity.

  5. Modeling and Control of a Manufacturing Flow Line using Partial Differential Equations

    NARCIS (Netherlands)

    Berg, van den R.A.; Lefeber, A.A.J.; Rooda, J.E.

    2008-01-01

    This brief deals with a control framework for manufacturing flow lines. For this framework, a continuous approximation model of the manufacturing system is required, which is computationally feasible and able to accurately describe the dynamics of the system (both throughput and flow time). Often

  6. Method and apparatus for controlling the flow rate of mercury in a flow system

    Science.gov (United States)

    Grossman, Mark W.; Speer, Richard

    1991-01-01

    A method for increasing the mercury flow rate to a photochemical mercury enrichment utilizing an entrainment system comprises the steps of passing a carrier gas over a pool of mercury maintained at a first temperature T1, wherein the carrier gas entrains mercury vapor; passing said mercury vapor entrained carrier gas to a second temperature zone T2 having temperature less than T1 to condense said entrained mercury vapor, thereby producing a saturated Hg condition in the carrier gas; and passing said saturated Hg carrier gas to said photochemical enrichment reactor.

  7. Analysis of design parameters and flow characteristics of the vortex valve for SIT flow control

    International Nuclear Information System (INIS)

    Hwang, Young Dong; Chang, Moon Hee; Kim, Seong O.; Kim, Young In.

    1997-01-01

    This study was performed to provide a technical basis for the development of the vortex valve which will be adopted in Korean Advanced Reactor. The influence of nondimensional and geometrical parameters of the vortex valve were investigated by analyzing the flow field of the vortex chamber, and the performance related parameters were evaluated by utilizing of the published experimental and analytical data. Also the level transients of the stand pipe were investigated by using of the simplified analytical model. In order to obtain the more detailed information on the vortex flow field, three dimensional preliminary analyses for the vortex valve design were conducted by FLUENT code. This study were carried out by using the simplified analytical model of the vortex valve and downstream pipe. However, the detailed analysis on the integrated system of the vortex valve with the as built design data and the required operating conditions should be performed to obtain the more accurate results on the vortex valve behavior. Also the experimental study over a wide range of operating conditions to develop the correlation of the design parameters and the performance verification should be performed for the practical design and engineering applications of the vortex valve. The results of this study can be used as a basic information for the development of the vortex valve design for the SIT of Korean Advanced Reactor. (author). 12 refs., 5 tabs., 33 figs

  8. On the properties and mechanisms of microjet arrays in crossflow for the control of flow separation

    Science.gov (United States)

    Fernandez, Erik J.

    By utilizing passive and active methods of flow control, the aerodynamic performance of external and internal components can be greatly improved. Recently however, the benefits of applying active flow control methods to turbomachinery components for improved fuel efficiency, reduced engine size, and greater operational envelope has sparked a renewed interest in some of these flow control techniques. The more attractive of these, is active control in the form of jets in cross flow. With their ability to be turned on and off, as well as their negligible effect on drag when not being actuated, they are well suited for applications such as compressor and turbine blades, engine inlet diffusers, internal engine passages, and general external aerodynamics. This study consists of two parts. The first is the application of active control on a low-pressure turbine (LPT) cascade to determine the effectiveness of microjet actuators on flow separation at relatively low speeds. The second study, motivated by the first, involves a parametric study on a more canonical model to examine the effects of various microjet parameters on the efficacy of separation control and to provide a better understanding of the relevant flow physics governing this control approach. With data obtained from velocity measurements across the wide parametric range, correlations for the growth of the counter-rotating vortex pairs generated by these actuators are deduced. From the information and models obtained throughout the study, basic suggestions for microjet actuator design are presented.

  9. On the Active and Passive Flow Separation Control Techniques over Airfoils

    Science.gov (United States)

    Moghaddam, Tohid; Banazadeh Neishabouri, Nafiseh

    2017-10-01

    In the present work, recent advances in the field of the active and passive flow separation control, particularly blowing and suction flow control techniques, applied on the common airfoils are briefly reviewed. This broad research area has remained the point of interest for many years as it is applicable to various applications. The suction and blowing flow control methods, among other methods, are more technically feasible and market ready techniques. It is well established that the uniform and/or oscillatory blowing and suction flow control mechanisms significantly improve the lift-to-drag ratio, and further, postpone the boundary layer separation as well as the stall. The oscillatory blowing and suction flow control, however, is more efficient compared to the uniform one. A wide range of parameters is involved in controlling the behavior of a blowing and/or suction flow control, including the location, length, and angle of the jet slots. The oscillation range of the jet slot is another substantial parameter.

  10. Occurrence and prevention of enhanced oxide deposition in boiler flow control orifices

    International Nuclear Information System (INIS)

    Woolsey, I.S.; Thomas, D.M.; Garbett, K.; Bignold, G.J.

    1989-10-01

    Once-through boilers, such as those of the AGRs, incorporate flow control orifices at the boiler inlet to ensure a satisfactory flow distribution and stability in the parallel flow paths of the boiler. Deposition of corrosion products in the flow control orifice leads to changes in the orifice pressure loss characteristics, which could lead to problems of flow maldistribution within the boiler, and any adverse consequences resulting from this, such as tube overheating. To date, AGR boiler inlet orifices have not suffered significant fouling due to corrosion products in the boiler feedwater. However, oxide deposition in orifices has been observed in other plants, and in experimental loops operating under conditions very similar to those at inlet to AGR boilers. The lack of deposition in AGR flow control orifices is therefore somewhat surprising. This Report describes studies carried out to examine the factors controlling oxide deposition in flow control orifices, the intention of the work being to explain why deposition has not occurred in AGR boilers to date, and to provide means of preventing deposition in the future should this prove necessary. (author)

  11. Active Fail-Safe Micro-Array Flow Control for Advanced Embedded Propulsion Systems

    Science.gov (United States)

    Anderson, Bernhard H.; Mace, James L.; Mani, Mori

    2009-01-01

    The primary objective of this research effort was to develop and analytically demonstrate enhanced first generation active "fail-safe" hybrid flow-control techniques to simultaneously manage the boundary layer on the vehicle fore-body and to control the secondary flow generated within modern serpentine or embedded inlet S-duct configurations. The enhanced first-generation technique focused on both micro-vanes and micro-ramps highly-integrated with micro -jets to provide nonlinear augmentation for the "strength' or effectiveness of highly-integrated flow control systems. The study focused on the micro -jet mass flow ratio (Wjet/Waip) range from 0.10 to 0.30 percent and jet total pressure ratios (Pjet/Po) from 1.0 to 3.0. The engine bleed airflow range under study represents about a 10 fold decrease in micro -jet airflow than previously required. Therefore, by pre-conditioning, or injecting a very small amount of high-pressure jet flow into the vortex generated by the micro-vane and/or micro-ramp, active flow control is achieved and substantial augmentation of the controlling flow is realized.

  12. Advanced Chemically-Based Actuation for Active Flow Control, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed SBIR program by Virtual AeroSurface Technologies (VAST) focuses on the development of a novel variant of pulsed blowing active flow control in which...

  13. Homeland Security and Information Control: A Model of Asymmetric Information Flows.

    Science.gov (United States)

    Maxwell, Terrence A.

    2003-01-01

    Summarizes some of the activities the United States government has undertaken to control the dissemination of information since 2001. It also explores, through a conceptual model of information flows, potential impacts and discontinuities between policy purposes and outcomes. (AEF)

  14. Numerical Investigation of Flow Control Feasibility with a Trailing Edge Flap

    International Nuclear Information System (INIS)

    Zhu, W J; Shen, W Z; Sørensen, J N

    2014-01-01

    This paper concerns a numerical study of employing an adaptive trailing edge flap to control the lift of an airfoil subject to unsteady inflow conditions. The periodically varying inflow is generated by two oscillating airfoils, which are located upstream of the controlled airfoil. To establish the control system, a standard PID controller is implemented in a finite volume based incompressible flow solver. An immersed boundary method is applied to treat the problem of simulating a deformable airfoil trailing edge. The flow field is solved using a 2D Reynolds averaged Navier-Stokes finite volume solver. In order to more accurately simulate wall bounded flows around the immersed boundary, a modified boundary condition is introduced in the k- ω turbulence model. As an example, turbulent flow over a NACA 64418 airfoil with a deformable trailing edge is investigated. Results from numerical simulations are convincing and may give some highlights for practical implementations of trailing edge flap to a wind turbine rotor blade

  15. The efficacy of centralized flow rate control in 802.11-based wireless mesh networks

    KAUST Repository

    Jamshaid, K.; Ward, P.; Karsten, M.; Shihada, Basem

    2013-01-01

    predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect

  16. Model-based Fuel Flow Control for Fossil-fired Power Plants

    DEFF Research Database (Denmark)

    Niemczyk, Piotr

    2010-01-01

    -fired power plants represent the largest reserve of such controllable power sources in several countries. However, their production take-up rates are limited, mainly due to poor fuel flow control. The thesis presents analysis of difficulties and potential improvements in the control of the coal grinding...

  17. Price-based optimal control of power flow in electrical energy transmission networks

    NARCIS (Netherlands)

    Jokic, A.; Lazar, M.; Bosch, van den P.P.J.; Bemporad, A.; Bicchi, A.; Buttazzo, G.

    2007-01-01

    This article presents a novel control scheme for achieving optimal power balancing and congestion control in electrical energy transmission networks via nodal prices. We develop an explicit controller that guarantees economically optimal steady-state operation while respecting all line flow

  18. A longitudinal analysis of salivary flow in control subjects and older adults with type 2 diabetes.

    Science.gov (United States)

    Chávez, E M; Borrell, L N; Taylor, G W; Ship, J A

    2001-02-01

    Many diabetics complain of xerostomia, a condition that can affect oral health, nutritional status, and diet selection. This study's purposes were (1) to investigate the effect on salivary flow of type 2 diabetes and change in glycemic control in a group of older adults over time and (2) to compare flow rates with subjective complaints of xerostomia. A total of 39 older adults, 24 with type 2 diabetes and 15 who were nondiabetic (controls), aged 54-90 years, participated in a 1-year follow-up study. Diabetic status was determined by means of glycosylated hemoglobin (HbA1c) levels and 2-hour glucose tolerance tests. Poor glycemic control was defined as HbA1c > 9%. Unstimulated whole, unstimulated parotid, and stimulated parotid saliva flow rates were measured for all subjects by a single examiner at baseline and 1 year later. Each subject completed a standardized xerostomia questionnaire at every visit. Age, sex, and duration of diabetes did not adversely affect salivary flow rates. Subjects with poorly controlled diabetes had significantly lower stimulated parotid saliva flow rates at both visits. There were no significant changes in flow rates over time on the basis of diabetic status or glycemic control. Subjects with diabetes reported significantly more complaints of thirst but not of xerostomia at 1 year. These results suggest that older adults with poorly controlled diabetes may have impaired salivary flow in comparison with subjects with better controlled diabetes and nondiabetic subjects, yet they may not have concomitant xerostomic complaints. There were no significant changes in salivary flow rates or glycemic control over the 1-year period.

  19. Active Control of Flow Separation Over an Airfoil

    Science.gov (United States)

    Ravindran, S. S.

    1999-01-01

    Designing an aircraft without conventional control surfaces is of interest to aerospace community. In this direction, smart actuator devices such as synthetic jets have been proposed to provide aircraft maneuverability instead of control surfaces. In this article, a numerical study is performed to investigate the effects of unsteady suction and blowing on airfoils. The unsteady suction and blowing is introduced at the leading edge of the airfoil in the form of tangential jet. Numerical solutions are obtained using Reynolds-Averaged viscous compressible Navier-Stokes equations. Unsteady suction and blowing is investigated as a means of separation control to obtain lift on airfoils. The effect of blowing coefficients on lift and drag is investigated. The numerical simulations are compared with experiments from the Tel-Aviv University (TAU). These results indicate that unsteady suction and blowing can be used as a means of separation control to generate lift on airfoils.

  20. Information flow due to controlled interference in entangled systems

    Indian Academy of Sciences (India)

    Abstract. We point out that controlled quantum interference corresponds to measurement in an incomplete basis and implies a nonlocal transfer of classical information. A test of whether such a generalized measurement is permissible in quantum theory is presented.

  1. Microadaptive Flow Control Applied to a Spinning Projectile

    National Research Council Canada - National Science Library

    McMichael, J; Lovas, A; Plostins, P; Sahu, J; Brown, G; Glezer, A

    2005-01-01

    ... technology developed, the flight control technology required to enable the MAFC on spinning projectiles, the design of the flight test and validation hardware, and the results of the open-loop flight test...

  2. Heat-flow and temperature control in Tian–Calvet microcalorimeters: toward higher detection limits

    International Nuclear Information System (INIS)

    Vilchiz-Bravo, L E; Pacheco-Vega, A; Handy, B E

    2010-01-01

    Strategies based on the principle of heat flow and temperature control were implemented, and experimentally tested, to increase the sensitivity of a Tian–Calvet microcalorimeter for measuring heats of adsorption. Here, both heat-flow and temperature control schemes were explored to diminish heater-induced thermal variations within the heat sink element, hence obtaining less noise in the baseline signal. PID controllers were implemented within a closed-loop system to perform the control actions in a calorimetric setup. The experimental results demonstrate that the heat flow control strategy provided a better baseline stability when compared to the temperature control. The effects on the results stemming from the type of power supply used were also investigated

  3. A distributed predictive control approach for periodic flow-based networks: application to drinking water systems

    Science.gov (United States)

    Grosso, Juan M.; Ocampo-Martinez, Carlos; Puig, Vicenç

    2017-10-01

    This paper proposes a distributed model predictive control approach designed to work in a cooperative manner for controlling flow-based networks showing periodic behaviours. Under this distributed approach, local controllers cooperate in order to enhance the performance of the whole flow network avoiding the use of a coordination layer. Alternatively, controllers use both the monolithic model of the network and the given global cost function to optimise the control inputs of the local controllers but taking into account the effect of their decisions over the remainder subsystems conforming the entire network. In this sense, a global (all-to-all) communication strategy is considered. Although the Pareto optimality cannot be reached due to the existence of non-sparse coupling constraints, the asymptotic convergence to a Nash equilibrium is guaranteed. The resultant strategy is tested and its effectiveness is shown when applied to a large-scale complex flow-based network: the Barcelona drinking water supply system.

  4. Control of 2D Flexible Structures by Confinement of Vibrations and Regulation of Their Energy Flow

    Directory of Open Access Journals (Sweden)

    Fakhreddine Landolsi

    2009-01-01

    Full Text Available In this paper, we investigate the control of 2D flexible structures by vibration confinement and the regulation of their energy flow along prespecified spatial paths. A discretized-model-based feedback strategy, aiming at confining and suppressing simultaneously the vibration, is proposed. It is assumed that the structure consists of parts that are sensitive to vibrations. The control design introduces a new pseudo-modal matrix derived from the computed eigenvectors of the discretized model. Simulations are presented to show the efficacy of the proposed control law. A parametric study is carried out to examine the effects of the different control parameters on the simultaneous confinement and suppression of vibrations. In addition, we conducted a set of simulations to investigate the flow control of vibrational energy during the confinement-suppression process. We found that the energy flow can be regulated via a set of control parameters for different confinement configurations.

  5. Sympathetic reflex control of blood flow in human peripheral tissues

    DEFF Research Database (Denmark)

    Henriksen, O

    1991-01-01

    Sympathetic vasoconstrictor reflexes are essential for the maintenance of arterial blood pressure in upright position. It has been generally believed that supraspinal sympathetic vasoconstrictor reflexes elicited by changes in baroreceptor activity play an important role. Recent studies on human...... sympathetic vasoconstrictor reflexes are blocked. Blood flow has been measure by the local 133Xe-technique. The results indicate the presence of spinal as well as supraspinal sympathetic vasoconstrictor reflexes to human peripheral tissues. Especially is emphasized the presence of a local sympathetic veno...... skeletal muscle, cutaneous and subcutaneous tissues of the limbs indicate that the situation is more complex. Measurements have been carried out during acute as well as chronic sympathetic denervation. Spinal sympathetic reflex mechanisms have been evaluated in tetraplegic patients, where supraspinal...

  6. Hot-Film and Hot-Wire Anemometry for a Boundary Layer Active Flow Control Test

    Science.gov (United States)

    Lenahan, Keven C.; Schatzman, David M.; Wilson, Jacob Samuel

    2013-01-01

    Unsteady active flow control (AFC) has been used experimentally for many years to minimize bluff-body drag. This technology could significantly improve performance of rotorcraft by cleaning up flow separation. It is important, then, that new actuator technologies be studied for application to future vehicles. A boundary layer wind tunnel was constructed with a 1ft-x-3ft test section and unsteady measurement instrumentation to study how AFC manipulates the boundary layer to overcome adverse pressure gradients and flow separation. This unsteady flow control research requires unsteady measurement methods. In order to measure the boundary layer characteristics, both hot-wire and hot-film Constant Temperature Anemometry is used. A hot-wire probe is mounted in the flow to measure velocity while a hot-film array lays on the test surface to measure skin friction. Hot-film sensors are connected to an anemometer, a Wheatstone bridge circuit with an output that corresponds to the dynamic flow response. From this output, the time varying flow field, turbulence, and flow reversal can be characterized. Tuning the anemometers requires a fan test on the hot-film sensors to adjust each output. This is a delicate process as several variables drastically affect the data, including control resistance, signal input, trim, and gain settings.

  7. CFD Analysis of Thermal Control System Using NX Thermal and Flow

    Science.gov (United States)

    Fortier, C. R.; Harris, M. F. (Editor); McConnell, S. (Editor)

    2014-01-01

    The Thermal Control Subsystem (TCS) is a key part of the Advanced Plant Habitat (APH) for the International Space Station (ISS). The purpose of this subsystem is to provide thermal control, mainly cooling, to the other APH subsystems. One of these subsystems, the Environmental Control Subsystem (ECS), controls the temperature and humidity of the growth chamber (GC) air to optimize the growth of plants in the habitat. The TCS provides thermal control to the ECS with three cold plates, which use Thermoelectric Coolers (TECs) to heat or cool water as needed to control the air temperature in the ECS system. In order to optimize the TCS design, pressure drop and heat transfer analyses were needed. The analysis for this system was performed in Siemens NX Thermal/Flow software (Version 8.5). NX Thermal/Flow has the ability to perform 1D or 3D flow solutions. The 1D flow solver can be used to represent simple geometries, such as pipes and tubes. The 1D flow method also has the ability to simulate either fluid only or fluid and wall regions. The 3D flow solver is similar to other Computational Fluid Dynamic (CFD) software. TCS performance was analyzed using both the 1D and 3D solvers. Each method produced different results, which will be evaluated and discussed.

  8. Reynolds-Averaged Navier-Stokes Analysis of Zero Efflux Flow Control over a Hump Model

    Science.gov (United States)

    Rumsey, Christopher L.

    2006-01-01

    The unsteady flow over a hump model with zero efflux oscillatory flow control is modeled computationally using the unsteady Reynolds-averaged Navier-Stokes equations. Three different turbulence models produce similar results, and do a reasonably good job predicting the general character of the unsteady surface pressure coefficients during the forced cycle. However, the turbulent shear stresses are underpredicted in magnitude inside the separation bubble, and the computed results predict too large a (mean) separation bubble compared with experiment. These missed predictions are consistent with earlier steady-state results using no-flow-control and steady suction, from a 2004 CFD validation workshop for synthetic jets.

  9. Controlled synthesis of colloidal silver nanoparticles in capillary micro-flow reactor

    International Nuclear Information System (INIS)

    He Shengtai; Liu Yulan; Maeda, Hideaki

    2008-01-01

    In this study, using a polytetrafluoroethylene (PTFE) capillary tube as a micro-flow reactor, well-dispersed colloidal silver nanoparticles were controllably synthesized with different flow rates of precursory solution. Scanning transmission electron microscopy images and UV-visible absorbance spectra showed that silver nanoparticles with large size can be prepared with slow flow rate in the PTFE capillary reactor. The effects of tube diameters on the growth of colloidal silver nanoparticles were investigated. Experiment results demonstrated that using tube with small diameter was more propitious for the controllable synthesis of silver nanoparticles with different sizes.

  10. Geometric optimization of cross-flow heat exchanger based on dynamic controllability

    Directory of Open Access Journals (Sweden)

    Alotaibi Sorour

    2008-01-01

    Full Text Available The operation of heat exchangers and other thermal equipments in the face of variable loads is usually controlled by manipulating inlet fluid temperatures or mass flow rates, where the controlled variable is usually one of the output temperatures. The aim of this work is to optimize the geometry of a tube with internal flow of water and an external cross-flow of air, based on its controllability characteristics. Controllability is a useful concept both from theoretical and practical perspective since it tells us if a particular output can be controlled by a particular input. This concept can also provide us with information about the easiest operating condition to control a particular output. A transient model of a tube in cross-flow is developed, where an implicit formulation is used for transient numerical solutions. The aspect ratio of the tube is optimized, subject to volume constraints, based on the optimum operation in terms of controllability. The reported optimized aspect ratio, water mass flow rate and controllability are studied for deferent external properties of the tube.

  11. Cluster-based control of a separating flow over a smoothly contoured ramp

    Science.gov (United States)

    Kaiser, Eurika; Noack, Bernd R.; Spohn, Andreas; Cattafesta, Louis N.; Morzyński, Marek

    2017-12-01

    The ability to manipulate and control fluid flows is of great importance in many scientific and engineering applications. The proposed closed-loop control framework addresses a key issue of model-based control: The actuation effect often results from slow dynamics of strongly nonlinear interactions which the flow reveals at timescales much longer than the prediction horizon of any model. Hence, we employ a probabilistic approach based on a cluster-based discretization of the Liouville equation for the evolution of the probability distribution. The proposed methodology frames high-dimensional, nonlinear dynamics into low-dimensional, probabilistic, linear dynamics which considerably simplifies the optimal control problem while preserving nonlinear actuation mechanisms. The data-driven approach builds upon a state space discretization using a clustering algorithm which groups kinematically similar flow states into a low number of clusters. The temporal evolution of the probability distribution on this set of clusters is then described by a control-dependent Markov model. This Markov model can be used as predictor for the ergodic probability distribution for a particular control law. This probability distribution approximates the long-term behavior of the original system on which basis the optimal control law is determined. We examine how the approach can be used to improve the open-loop actuation in a separating flow dominated by Kelvin-Helmholtz shedding. For this purpose, the feature space, in which the model is learned, and the admissible control inputs are tailored to strongly oscillatory flows.

  12. Suppression of chaos via control of energy flow

    Science.gov (United States)

    Guo, Shengli; Ma, Jun; Alsaedi, Ahmed

    2018-03-01

    Continuous energy supply is critical and important to support oscillating behaviour; otherwise, the oscillator will die. For nonlinear and chaotic circuits, enough energy supply is also important to keep electric devices working. In this paper, Hamilton energy is calculated for dimensionless dynamical system (e.g., the chaotic Lorenz system) using Helmholtz's theorem. The Hamilton energy is considered as a new variable and then the dynamical system is controlled by using the scheme of energy feedback. It is found that chaos can be suppressed even when intermittent feedback scheme is applied. This scheme is effective to control chaos and to stabilise other dynamical systems.

  13. Subsurface barrier design alternatives for confinement and controlled advection flow

    International Nuclear Information System (INIS)

    Phillips, S.J.; Stewart, W.E.; Alexander, R.G.; Cantrell, K.J.; McLaughlin, T.J.

    1994-02-01

    Various technologies and designs are being considered to serve as subsurface barriers to confine or control contaminant migration from underground waste storage or disposal structures containing radioactive and hazardous wastes. Alternatives including direct-coupled flood and controlled advection designs are described as preconceptual examples. Prototype geotechnical equipment for testing and demonstration of these alternative designs tested at the Hanford Geotechnical Development and Test Facility and the Hanford Small-Tube Lysimeter Facility include mobile high-pressure injectors and pumps, mobile transport and pumping units, vibratory and impact pile drivers, and mobile batching systems. Preliminary laboratory testing of barrier materials and additive sequestering agents have been completed and are described

  14. A novel feedback control system – Controlling the material flow in deep drawing using distributed blank-holder force

    DEFF Research Database (Denmark)

    Endelt, Benny Ørtoft; Tommerup, Søren; Danckert, Joachim

    2013-01-01

    The performance of a feedback control system is often limited by the quality of the model on which it is based, and often the controller design is based on trial and error due to insufficient modeling capabilities. A framework is proposed where the controller design is based on classical state...... on a deep drawing operation where the objective was to control material flow throughout the part using only spatial information regarding flange draw-in. The control system controls both the magnitude and distribution of the blank-holder force. The methodology proved stable and flexible with respect...

  15. Remote Voltage Control Using the Holomorphic Embedding Load Flow Method

    DEFF Research Database (Denmark)

    Liu, Chengxi; Qin, Nan; Sun, Kai

    2018-01-01

    such that the approach can remotely control the voltage magnitudes of desired buses. The proposed approach is compared with a conventional Newton-Raphson approach by study cases on the IEEE New England 39-bus system. The results show that the proposed approach achieves a larger convergence region....

  16. Cerebral blood flow control in small vessel disease

    NARCIS (Netherlands)

    Kim, Y.S.

    2014-01-01

    In normal conditions CBF is maintained over a wide range of perfusion pressures (ca. 60~150 mm Hg) by two main control systems, i.e. mechanoregulation, referring to CA, and chemoregulation, also known as cerebrovascular CO2 responsiveness reflecting the vasodilatory capacity of the cerebral

  17. The combinatorics of nonlinear controllability and noncommuting flows

    International Nuclear Information System (INIS)

    Kawski, M.

    2002-01-01

    These notes accompany four lectures, giving an introduction to new developments in, and tools for problems in nonlinear control. Roughly speaking, after the successful development, starting in the 1960s, of methods from linear algebra, complex analysis and functional analysis for solving linear control problems, the 1970s and 1980s saw the emergence of differential geometric tools that were to mimic that success for nonlinear systems. In the past 30 years this theory has matured, and now connects with many other branches of mathematics. The focus of these notes is the role of algebraic combinatorics for both illuminating structures and providing computational tools for nonlinear systems. On the control side, we focus on problems connected with controllability, although the combinatorial tools obviously have just as much use for other control problems, including e.g. path-planning, realization theory, and observability. The lectures are meant to be an introduction, sketching the road from the comparatively naive, bare-handed constructions used in the early years, to the elegant and powerful insights from recent years. One of the main targets is to develop an explicit, continuous analogue of the classical Campbell-Baker-Hausdorff formula, and of a related exponential product expansion. The purpose of such formulae is to separate the time-dependent and control-dependent parts of solution curves from the invariant underlying geometrical structure inherent in each control system. The key theme is that effective tools (including effective notation) from algebraic combinatorics are essential, for both theoretical analysis and for practical computation (beyond some miniscule academic examples). On a.practical level we want the reader to take home the message to never write out complicated iterated integrals, as it is both a waste of paper and time, as it obscures the underlying structure. On the theoretical level, the key object is the chronological algebra isomorphism

  18. Active control of annular flow-induced vibration of axisymmetric elastic beam by the local gap width control

    International Nuclear Information System (INIS)

    Takada, Shoji; Shintani, Atsuhiko; Ito, Tomohiro; Fujita, Katsuhisa

    2011-01-01

    Flow-induced vibration may occur in the structures such as elastic beams subjected to annular flow in the narrow passage. Once the flow-induced vibration occurs, vibration amplitude becomes larger, consequently it causes a lot of troubles such as fatigue or failure in mechanical structures. In this paper, for the purpose to avoid these troubles, the active control of vibration of an axisymmetric elastic beam subjected to annular flow is investigated. An air-pressured actuator is attached on the surface of the circular cylinder for the vibrational control. As the shape of the actuator changes by control, the gap width in narrow passage changes, which causes the change of the fluid pressure. Therefore, the vibration of the fluid-structure coupled system can be suppressed. The fluid-structure coupled equation based on the Euler-Bernoulli type of partial differential equation and the Navier-Stokes equations is analytically derived including control terms. By applying the optimal control law to the coupled system, the unstable behavior is stabilized. The stability of the coupled system is investigated by eigenvalue analyses of controlled coupled equations. Numerical simulations are performed to investigate the efficiency of the proposed control method. (author)

  19. Congestion and flow control in signaling system no. 7: Impacts of intelligent networks and new services

    Science.gov (United States)

    Zepf, Joachim; Rufa, Gerhard

    1994-04-01

    This paper focuses on the transient performance analysis of the congestion and flow control mechanisms in CCITT Signaling System No. 7 (SS7). Special attention is directed to the impacts of the introduction of intelligent services and new applications, e.g., Freephone, credit card services, user-to-user signaling, etc. In particular, we show that signaling traffic characteristics like signaling scenarios or signaling message length as well as end-to-end signaling capabilities have a significant influence on the congestion and flow control and, therefore, on the real-time signaling performance. One important result of our performance studies is that if, e.g., intelligent services are introduced, the SS7 congestion and flow control does not work correctly. To solve this problem, some reinvestigations into these mechanisms would be necessary. Therefore, some approaches, e.g., modification of the Signaling Connection Control Part (SCCP) congestion control, usage of the SCCP relay function, or a redesign of the MTP flow control procedures are discussed in order to guarantee the efficacy of the congestion and flow control mechanisms also in the future.

  20. Steady flow torques in a servo motor operated rotary directional control valve

    International Nuclear Information System (INIS)

    Wang, He; Gong, Guofang; Zhou, Hongbin; Wang, Wei

    2016-01-01

    Highlights: • A novel servo motor operated rotary directional control valve is proposed. • Steady flow torque is a crucial issue that affects rotary valve performance. • Steady flow torque is analyzed on the aspects of theory, simulation and experiment. • Change law of the steady flow torque with spool rotation angle is explored. • Effect of pressure drop and flow rate on the steady flow torque is studied. - Abstract: In this paper, a servo motor operated rotary directional control valve is proposed, and a systematic analysis of steady flow torques in this valve is provided by theoretical calculation, CFD simulation and experimental test. In the analysis, spool rotation angle corresponding to the maximum orifice opening is tagged as 0°. Over a complete change cycle of the orifice, the range of spool rotation angle is symmetric about 0°. The results show that the direction of steady flow torques in this valve is always the direction of orifice closing. The steady flow torques serve as resistances to the spool rotation when the orifice opening increases, while impetuses to the spool rotation when the orifice opening decreases. At a certain pressure drop or flow rate, steady flow torques are approximately equal and opposite when at spool rotation angles which are symmetric about 0°. When the spool rotates from 0°, at a certain pressure drop, their values increase first then decrease with the spool rotation and reach their maximum values at an angle corresponding to about 1/2 of the maximum orifice opening, and at a certain flow rate, their values increase with the spool rotation. The steady flow torques in this valve are the sums of those in the meter-in and meter-out valve chambers. At a certain spool rotation angle, steady flow torques in the meter-in and meter-out valve chambers are approximately proportional to the pressure drop and the second power of the flow rate through the orifice. Theoretical calculation and CFD simulation can be validated by

  1. A Novel Approach to Adaptive Flow Separation Control

    Science.gov (United States)

    2016-09-03

    Artificial Intelligence ( ) TOTAL: 1 Books Number of Manuscripts: Patents Submitted Patents Awarded Awards Graduate Students Names of Post Doctorates...Education, February 2015. ASME Fellow, April 2013. Received Book TOTAL: Received Book Chapter TOTAL: PERCENT_SUPPORTEDNAME FTE Equivalent: Total Number...and other fields such as power system control and automotive engine tuning. References 1. B. Reese, F. Alvi, and E. G. Collins, “A

  2. Flow mixing inside a control-rod guide tube – Experimental tests and CFD simulations

    International Nuclear Information System (INIS)

    Angele, Kristian; Odemark, Ylva; Cehlin, Mathias; Hemström, Bengt; Högström, Carl-Maikel; Henriksson, Mats; Tinoco, Hernan; Lindqvist, Hans

    2011-01-01

    This paper covers a combined experimental and computational effort carried out at Vattenfall Research and Development AB in order to study the thermal mixing in the annular region between a top tube and a control-rod stem. The low frequency thermal fluctuations in this region can result in problems with thermal fatigue and have caused cracks in the control-rod stems of several nuclear reactors (). The flow in the vertical annular region formed by the top tube and the control-rod stem is characterized by the mixing of hot bypass flow with cold crud-removal flow. The crud-removal flow is flowing upwards along the control-rod stem, and the warmer bypass flow is entering through eight horizontal holes positioned in the lower part of the guide tube and four holes in the upper part of the top tube, forming jets. Two full-scale models of a control rod, including the control-rod stem and the guide tube, were constructed. The first model, designed to work at atmospheric conditions, was made of Plexiglass, in order to be able to visualize the mixing process, whereas the second one was made of steel to allow for a higher temperature difference between the two flows, and the heating of the top tube. CFD simulations of the case at atmospheric conditions were also carried out. Both the experiments and the simulations showed that the mixing region between the cold crud-removal flow and the warm bypass flow is dominated by large flow structures coming from above. The process is characterized by low frequency, high amplitude temperature fluctuations. The process is basically hydrodynamic, caused by the downward transport of flow structures originated at the upper bypass inlets. The damping thermal effects through buoyancy is of secondary importance, as also the scaling analysis shows, however a slight damping of the temperature fluctuations can be seen due to natural convection due to a pre-heating of the cold crud-removal flow. The comparison between numerical and experimental

  3. Nitrogen regulation of transpiration controls mass-flow acquisition of nutrients.

    Science.gov (United States)

    Matimati, Ignatious; Verboom, G Anthony; Cramer, Michael D

    2014-01-01

    Transpiration may enhance mass-flow of nutrients to roots, especially in low-nutrient soils or where the root system is not extensively developed. Previous work suggested that nitrogen (N) may regulate mass-flow of nutrients. Experiments were conducted to determine whether N regulates water fluxes, and whether this regulation has a functional role in controlling the mass-flow of nutrients to roots. Phaseolus vulgaris were grown in troughs designed to create an N availability gradient by restricting roots from intercepting a slow-release N source, which was placed at one of six distances behind a 25 μm mesh from which nutrients could move by diffusion or mass-flow (termed 'mass-flow' treatment). Control plants had the N source supplied directly to their root zone so that N was available through interception, mass-flow, and diffusion (termed 'interception' treatment). 'Mass-flow' plants closest to the N source exhibited 2.9-fold higher transpiration (E), 2.6-fold higher stomatal conductance (gs), 1.2-fold higher intercellular [CO2] (Ci), and 3.4-fold lower water use efficiency than 'interception' plants, despite comparable values of photosynthetic rate (A). E, gs, and Ci first increased and then decreased with increasing distance from the N source to values even lower than those of 'interception' plants. 'Mass-flow' plants accumulated phosphorus and potassium, and had maximum concentrations at 10mm from the N source. Overall, N availability regulated transpiration-driven mass-flow of nutrients from substrate zones that were inaccessible to roots. Thus when water is available, mass-flow may partially substitute for root density in providing access to nutrients without incurring the costs of root extension, although the efficacy of mass-flow also depends on soil nutrient retention and hydraulic properties.

  4. The shear flow processing of controlled DNA tethering and stretching for organic molecular electronics.

    Science.gov (United States)

    Yu, Guihua; Kushwaha, Amit; Lee, Jungkyu K; Shaqfeh, Eric S G; Bao, Zhenan

    2011-01-25

    DNA has been recently explored as a powerful tool for developing molecular scaffolds for making reproducible and reliable metal contacts to single organic semiconducting molecules. A critical step in the process of exploiting DNA-organic molecule-DNA (DOD) array structures is the controlled tethering and stretching of DNA molecules. Here we report the development of reproducible surface chemistry for tethering DNA molecules at tunable density and demonstrate shear flow processing as a rationally controlled approach for stretching/aligning DNA molecules of various lengths. Through enzymatic cleavage of λ-phage DNA to yield a series of DNA chains of various lengths from 17.3 μm down to 4.2 μm, we have investigated the flow/extension behavior of these tethered DNA molecules under different flow strengths in the flow-gradient plane. We compared Brownian dynamic simulations for the flow dynamics of tethered λ-DNA in shear, and found our flow-gradient plane experimental results matched well with our bead-spring simulations. The shear flow processing demonstrated in our studies represents a controllable approach for tethering and stretching DNA molecules of various lengths. Together with further metallization of DNA chains within DOD structures, this bottom-up approach can potentially enable efficient and reliable fabrication of large-scale nanoelectronic devices based on single organic molecules, therefore opening opportunities in both fundamental understanding of charge transport at the single molecular level and many exciting applications for ever-shrinking molecular circuits.

  5. Movable shark scales act as a passive dynamic micro-roughness to control flow separation

    International Nuclear Information System (INIS)

    Lang, Amy W; Bradshaw, Michael T; Smith, Jonathon A; Wheelus, Jennifer N; Motta, Philip J; Habegger, Maria L; Hueter, Robert E

    2014-01-01

    Shark scales on fast-swimming sharks have been shown to be movable to angles in excess of 50°, and we hypothesize that this characteristic gives this shark skin a preferred flow direction. During the onset of separation, flow reversal is initiated close to the surface. However, the movable scales would be actuated by the reversed flow thereby causing a greater resistance to any further flow reversal and this mechanism would disrupt the process leading to eventual flow separation. Here we report for the first time experimental evidence of the separation control capability of real shark skin through water tunnel testing. Using skin samples from a shortfin mako Isurus oxyrinchus, we tested a pectoral fin and flank skin attached to a NACA 4412 hydrofoil and separation control was observed in the presence of movable shark scales under certain conditions in both cases. We hypothesize that the scales provide a passive, flow-actuated mechanism acting as a dynamic micro-roughness to control flow separation. (paper)

  6. Three Flow Features behind the Flow Control Authority of DBD Plasma Actuator: Result of High-Fidelity Simulations and the Related Experiments

    Directory of Open Access Journals (Sweden)

    Kozo Fujii

    2018-04-01

    Full Text Available Both computational and experimental studies are conducted for understanding of the flow separation control mechanism of a DBD (dielectric barrier discharge plasma actuator. Low speed flows over an airfoil are considered. A DBD plasma actuator is attached near the leading edge of an airfoil and the mechanism of flow control of this small device is discussed. The DBD plasma actuator, especially in burst mode, is shown to be very effective for controlling flow separation at Reynolds number of 6.3 × 104, when applied to the flows at an angle of attack higher than the stall. The analysis reveals that the flow structure includes three remarkable features that provide good authority for flow separation control with the appropriate actuator parameters. With proper setting of the actuator parameters to enhance the effective flow features for the application, good flow control can be achieved. Based on the analysis, guidelines for the effective use of DBD plasma actuators are proposed. A DBD plasma actuator is also applied to the flows under cruise conditions. With the DBD plasma actuator attached, a simple airfoil turns out to show higher lift-to-drag ratio than a well-designed airfoil.

  7. Baseline Validation of Unstructured Grid Reynolds-Averaged Navier-Stokes Toward Flow Control

    Science.gov (United States)

    Joslin, Ronald D.; Viken, Sally A.

    2001-01-01

    The value of the use of the Reynolds-averaged Navier-Stokes methodology for active flow control applications is assessed. An experimental flow control database exists for a NACA0015 airfoil modified at the leading edge to implement a fluidic actuator; hence, this configuration is used. Computational results are documented for the baseline wing configuration (no control) with the experimental results and assumes two-dimensional flow. The baseline wing configuration has discontinuities at the leading edge, trailing edge, and aft of midchord on the upper surface. A limited number of active flow control applications have been tested in the laboratory and in flight. These applications include dynamic stall control using a deformable leading edge, separation control for takeoff and landing flight conditions using piezoelectric devices, pulsed vortex generators, zero-net-mass oscillations, and thrust vectoring with zero-net-mass piezoelectric-driven oscillatory actuation. As yet, there is no definitive comparison with experimental data that indicates current computational capabilities can quantitatively predict the large aerodynamic performance gains achieved with active flow control in the laboratory. However, one study using the Reynolds-averaged Navier-Stokes (RANS) methodology has shown good quantitative agreement with experimental results for an isolated zero-net-mass actuator. In addition, some recent studies have used RANS to demonstrate qualitative performance gains compared with the experimental data for separation control on an airfoil. Those quantitative comparisons for both baseline and flow control cases indicated that computational results were in poor quantitative agreement with the experiments. The current research thrust will investigate the potential use of an unstructured grid RANS approach to predict aerodynamic performance for active flow control applications building on the early studies. First the computational results must quantitatively match

  8. Genetic and environmental influences on the relationship between flow proneness, locus of control and behavioral inhibition.

    Directory of Open Access Journals (Sweden)

    Miriam A Mosing

    Full Text Available Flow is a psychological state of high but subjectively effortless attention that typically occurs during active performance of challenging tasks and is accompanied by a sense of automaticity, high control, low self-awareness, and enjoyment. Flow proneness is associated with traits and behaviors related to low neuroticism such as emotional stability, conscientiousness, active coping, self-esteem and life satisfaction. Little is known about the genetic architecture of flow proneness, behavioral inhibition and locus of control--traits also associated with neuroticism--and their interrelation. Here, we hypothesized that individuals low in behavioral inhibition and with an internal locus of control would be more likely to experience flow and explored the genetic and environmental architecture of the relationship between the three variables. Behavioral inhibition and locus of control was measured in a large population sample of 3,375 full twin pairs and 4,527 single twins, about 26% of whom also scored the flow proneness questionnaire. Findings revealed significant but relatively low correlations between the three traits and moderate heritability estimates of .41, .45, and .30 for flow proneness, behavioral inhibition, and locus of control, respectively, with some indication of non-additive genetic influences. For behavioral inhibition we found significant sex differences in heritability, with females showing a higher estimate including significant non-additive genetic influences, while in males the entire heritability was due to additive genetic variance. We also found a mainly genetically mediated relationship between the three traits, suggesting that individuals who are genetically predisposed to experience flow, show less behavioral inhibition (less anxious and feel that they are in control of their own destiny (internal locus of control. We discuss that some of the genes underlying this relationship may include those influencing the function of

  9. Genetic and environmental influences on the relationship between flow proneness, locus of control and behavioral inhibition.

    Science.gov (United States)

    Mosing, Miriam A; Pedersen, Nancy L; Cesarini, David; Johannesson, Magnus; Magnusson, Patrik K E; Nakamura, Jeanne; Madison, Guy; Ullén, Fredrik

    2012-01-01

    Flow is a psychological state of high but subjectively effortless attention that typically occurs during active performance of challenging tasks and is accompanied by a sense of automaticity, high control, low self-awareness, and enjoyment. Flow proneness is associated with traits and behaviors related to low neuroticism such as emotional stability, conscientiousness, active coping, self-esteem and life satisfaction. Little is known about the genetic architecture of flow proneness, behavioral inhibition and locus of control--traits also associated with neuroticism--and their interrelation. Here, we hypothesized that individuals low in behavioral inhibition and with an internal locus of control would be more likely to experience flow and explored the genetic and environmental architecture of the relationship between the three variables. Behavioral inhibition and locus of control was measured in a large population sample of 3,375 full twin pairs and 4,527 single twins, about 26% of whom also scored the flow proneness questionnaire. Findings revealed significant but relatively low correlations between the three traits and moderate heritability estimates of .41, .45, and .30 for flow proneness, behavioral inhibition, and locus of control, respectively, with some indication of non-additive genetic influences. For behavioral inhibition we found significant sex differences in heritability, with females showing a higher estimate including significant non-additive genetic influences, while in males the entire heritability was due to additive genetic variance. We also found a mainly genetically mediated relationship between the three traits, suggesting that individuals who are genetically predisposed to experience flow, show less behavioral inhibition (less anxious) and feel that they are in control of their own destiny (internal locus of control). We discuss that some of the genes underlying this relationship may include those influencing the function of dopaminergic neural

  10. Experimental study of the active control applied to the flow past a backward facing ramp

    Science.gov (United States)

    Hlevca, Dan; Gilliéron, Patrick; Grasso, Francesco

    2018-03-01

    An experimental study of open loop active flow control on a backward facing ramp is presented. The ramp has finite span and a slant angle of 25°. Wind tunnel experiments were performed both for the uncontrolled and the controlled cases where time periodic forcing by pulsed jets is considered. The control system exploits an electro-magnetic valve system to generate pulsed jets with an operating frequency and duty cycle ranging, respectively, between 50 and 250 Hz and between 25 and 60%. A parametric study was carried out for three different freestream velocities and varying the frequency of the pulsed jets and the duty cycle. The control strategy relies on the injection of periodic perturbations before separation at the edge of the slant, considering various combinations of frequencies and duty cycles while keeping constant the blowing time for every Reynolds number, so as to excite the flow with the same jet structure over different actuation cycle extents. The receptivity of the flow to periodic forcing was assessed by characterizing mean and unsteady flow properties, turbulence statistics and flow topology. The study focused on the impact of control on reattachement and showed that the flow locks with excitation frequencies typical of initial Kelvin-Helmholtz instabilities. However, the flow was found to respond to any injected unsteady perturbation locking to the forcing frequencies and the extent of the region where locking occurs was found to be of the order of a few slant heights. A relaxation process was observed and the flow was found to relax past the slant trailing edge toward frequencies close to the natural ones.

  11. Research on Pulsed Jet Flow Control without External Energy in a Blade Cascade

    Directory of Open Access Journals (Sweden)

    Jie Chen

    2017-12-01

    Full Text Available To control the flow separation in the compressors, a novel pulsed jet concept without external energy injection is proposed. The new concept designs a slot in the middle of the blade and sets a micro device to switch the slot periodically. Such a structure is expected to generate a pulsed jet by the pressure difference between the pressure side and the suction side of the blade. In order to analyze the interaction between the pulsed jet and unsteady separated flow, our numerical and experimental study is based on a specific cascade (with a flow separation inside and a pulsed jet (one of the unsteady flow control method. The experimental and numerical results both show that when the frequency of pulsed jet is approximate to that of the separation vortex, then the control tends to be more effective. Based on the numerical simulations, the proper orthogonal decomposition (POD is then used to reveal the control mechanism, extracting the different time-space structures from the original field. The results with the aid of POD show that the pulsed jet can redistribute the kinetic energy of each mode, and strengthen or weaken certain modes, particularly, while the steady jet reduces the kinetic energy of high-order modes in whole. Also, pulsed jet with proper parameters can transfer the energy from higher modes to the first flow mode (averaged flow, which is due to the conversion of the spatial vortical structures and the time evolution of the modes.

  12. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    International Nuclear Information System (INIS)

    Gilmore, Mark Allen

    2017-01-01

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB's)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB's] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  13. Numerical and Experimental Investigation of Turbulent Transport Control via Shaping of Radial Plasma Flow Profiles

    Energy Technology Data Exchange (ETDEWEB)

    Gilmore, Mark Allen [Univ. of New Mexico, Albuquerque, NM (United States)

    2017-02-05

    Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB’s)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB’s] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.

  14. Robust and Optimal Control of Magnetic Microparticles inside Fluidic Channels with Time-Varying Flow Rates

    Directory of Open Access Journals (Sweden)

    Islam S.M. Khalil

    2016-06-01

    Full Text Available Targeted therapy using magnetic microparticles and nanoparticles has the potential to mitigate the negative side-effects associated with conventional medical treatment. Major technological challenges still need to be addressed in order to translate these particles into in vivo applications. For example, magnetic particles need to be navigated controllably in vessels against flowing streams of body fluid. This paper describes the motion control of paramagnetic microparticles in the flowing streams of fluidic channels with time-varying flow rates (maximum flow is 35 ml.hr−1. This control is designed using a magnetic-based proportional-derivative (PD control system to compensate for the time-varying flow inside the channels (with width and depth of 2 mm and 1.5 mm, respectively. First, we achieve point-to-point motion control against and along flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1. The average speeds of single microparticle (with average diameter of 100 μm against flow rates of 6 ml.hr−1 and 30 ml.hr−1 are calculated to be 45 μm.s−1 and 15 μm.s−1, respectively. Second, we implement PD control with disturbance estimation and compensation. This control decreases the steady-state error by 50%, 70%, 73%, and 78% at flow rates of 4 ml.hr−1, 6 ml.hr−1, 17 ml.hr−1, and 35 ml.hr−1, respectively. Finally, we consider the problem of finding the optimal path (minimal kinetic energy between two points using calculus of variation, against the mentioned flow rates. Not only do we find that an optimal path between two collinear points with the direction of maximum flow (middle of the fluidic channel decreases the rise time of the microparticles, but we also decrease the input current that is supplied to the electromagnetic coils by minimizing the kinetic energy of the microparticles, compared to a PD control with disturbance compensation.

  15. Nonlinear output feedback control of underwater vehicle propellers using feedback form estimated axial flow velocity

    DEFF Research Database (Denmark)

    Fossen, T. I.; Blanke, Mogens

    2000-01-01

    Accurate propeller shaft speed controllers can be designed by using nonlinear control theory and feedback from the axial water velocity in the propeller disc. In this paper, an output feedback controller is derived, reconstructing the axial flow velocity from vehicle speed measurements, using...... a three-state model of propeller shaft speed, forward (surge) speed of the vehicle, and the axial flow velocity. Lyapunov stability theory is used to prove that a nonlinear observer combined with an output feedback integral controller provide exponential stability. The output feedback controller...... compensates for variations in thrust due to time variations in advance speed. This is a major problem when applying conventional vehicle-propeller control systems, The proposed controller is simulated for an underwater vehicle equipped with a single propeller. The simulations demonstrate that the axial water...

  16. Model Reference Adaptive Control of the Air Flow Rate of Centrifugal Compressor Using State Space Method

    International Nuclear Information System (INIS)

    Han, Jaeyoung; Jung, Mooncheong; Yu, Sangseok; Yi, Sun

    2016-01-01

    In this study, a model reference adaptive controller is developed to regulate the outlet air flow rate of centrifugal compressor for automotive supercharger. The centrifugal compressor is developed using the analytical based method to predict the transient behavior of operating and the designed model is validated with experimental data to confirm the system accuracy. The model reference adaptive control structure consists of a compressor model and a MRAC(model reference adaptive control) mechanism. The feedback control do not robust with variation of system parameter but the applied adaptive control is robust even if the system parameter is changed. As a result, the MRAC was regulated to reference air flow rate. Also MRAC was found to be more robust control compared with the feedback control even if the system parameter is changed.

  17. Simultaneous positioning and orientation of a single nano-object by flow control: theory and simulations

    International Nuclear Information System (INIS)

    Mathai, Pramod P; Berglund, Andrew J; Alexander Liddle, J; Shapiro, Benjamin A

    2011-01-01

    In this paper, we theoretically describe a method to simultaneously control both the position and orientation of single nano-objects in fluids by precisely controlling the flow around them. We develop and simulate a control law that uses electro-osmotic flow (EOF) actuation to translate and rotate rigid nano-objects in two spatial dimensions. Using EOF to control nano-objects offers advantages as compared to other approaches: a wide class of objects can be manipulated (no magnetic or electric dipole moments are needed), the object can be controlled over a long range (>100 μm) with sub-micrometer accuracy, and control may be achieved with simple polydimethylsiloxane (PDMS) devices. We demonstrate the theory and numerical solutions that will enable deterministic control of the position and orientation of a nano-object in solution, which can be used, for example, to integrate nanostructures in circuits and orient sensors to probe living cells.

  18. Model Reference Adaptive Control of the Air Flow Rate of Centrifugal Compressor Using State Space Method

    Energy Technology Data Exchange (ETDEWEB)

    Han, Jaeyoung; Jung, Mooncheong; Yu, Sangseok [Chungnam Nat’l Univ., Daejeon (Korea, Republic of); Yi, Sun [North Carolina A and T State Univ., Raleigh (United States)

    2016-08-15

    In this study, a model reference adaptive controller is developed to regulate the outlet air flow rate of centrifugal compressor for automotive supercharger. The centrifugal compressor is developed using the analytical based method to predict the transient behavior of operating and the designed model is validated with experimental data to confirm the system accuracy. The model reference adaptive control structure consists of a compressor model and a MRAC(model reference adaptive control) mechanism. The feedback control do not robust with variation of system parameter but the applied adaptive control is robust even if the system parameter is changed. As a result, the MRAC was regulated to reference air flow rate. Also MRAC was found to be more robust control compared with the feedback control even if the system parameter is changed.

  19. On mill flow rate and fineness control in cement grinding circuits: instability and delayed measurements

    International Nuclear Information System (INIS)

    Lepore, R.; Boulvin, M.; Renotte, C.; Remy, M.

    1999-01-01

    A control structure for the mill flow rate and the product fineness is designed, with the feed flow rate and the classifier characteristic as the manipulated variables. Experimental results from a plant highlight the instability of the grinding circuit. A model previously developed by the authors stresses the major influence of the classifier nonlinearities onto this instability. A cascade control structure has been designed and implemented on site. The measurements of the product fineness, sensitive to material grindability fluctuations, are randomly time-delayed. The control structure uses a fineness estimator based on an adaptive scheme and a time delay compensator. (author)

  20. Control-flow analysis of function calls and returns by abstract interpretation

    DEFF Research Database (Denmark)

    Midtgaard, Jan; Jensen, Thomas P.

    2009-01-01

    We derive a control-flow analysis that approximates the interprocedural control-flow of both function calls and returns in the presence of first-class functions and tail-call optimization. In addition to an abstract environment, our analysis computes for each expression an abstract control stack......, effectively approximating where function calls return across optimized tail calls. The analysis is systematically calculated by abstract interpretation of the stack-based CaEK abstract machine of Flanagan et al. using a series of Galois connections. Abstract interpretation provides a unifying setting in which...

  1. Localized modelling and feedback control of linear instabilities in 2-D wall bounded shear flows

    Science.gov (United States)

    Tol, Henry; Kotsonis, Marios; de Visser, Coen

    2016-11-01

    A new approach is presented for control of instabilities in 2-D wall bounded shear flows described by the linearized Navier-Stokes equations (LNSE). The control design accounts both for spatially localized actuators/sensors and the dominant perturbation dynamics in an optimal control framework. An inflow disturbance model is proposed for streamwise instabilities that drive laminar-turbulent transition. The perturbation modes that contribute to the transition process can be selected and are included in the control design. A reduced order model is derived from the LNSE that captures the input-output behavior and the dominant perturbation dynamics. This model is used to design an optimal controller for suppressing the instability growth. A 2-D channel flow and a 2-D boundary layer flow over a flat plate are considered as application cases. Disturbances are generated upstream of the control domain and the resulting flow perturbations are estimated/controlled using wall shear measurements and localized unsteady blowing and suction at the wall. It will be shown that the controller is able to cancel the perturbations and is robust to unmodelled disturbances.

  2. A new approach in development of data flow control and investigation system for computer networks

    International Nuclear Information System (INIS)

    Frolov, I.; Vaguine, A.; Silin, A.

    1992-01-01

    This paper describes a new approach in development of data flow control and investigation system for computer networks. This approach was developed and applied in the Moscow Radiotechnical Institute for control and investigations of Institute computer network. It allowed us to solve our network current problems successfully. Description of our approach is represented below along with the most interesting results of our work. (author)

  3. Improved Performance of Personalized Ventilation by Control of the Convection Flow around Occupant Body

    DEFF Research Database (Denmark)

    Bolashikov, Zhecho Dimitrov; Melikov, Arsen Krikor; Krenek, Miroslav

    2009-01-01

    This paper reports on methods of control of the free convection flow around human body aiming at improvement of inhaled air quality for occupants at workstations with personalized ventilation (PV). Two methods of control were developed and explored: passive - blocking the free convection developm......This paper reports on methods of control of the free convection flow around human body aiming at improvement of inhaled air quality for occupants at workstations with personalized ventilation (PV). Two methods of control were developed and explored: passive - blocking the free convection......-scale test room with background mixing ventilation. Thermal manikin with realistic free convection flow was used. The PV supplied air from front/above towards the face. All measurements were performed under isothermal conditions at 20 °C and 26 °C. The air in the test room was mixed with tracer gas, while...

  4. Numerical Analysis of the Cavity Flow subjected to Passive Controls Techniques

    Science.gov (United States)

    Melih Guleren, Kursad; Turk, Seyfettin; Mirza Demircan, Osman; Demir, Oguzhan

    2018-03-01

    Open-source flow solvers are getting more and more popular for the analysis of challenging flow problems in aeronautical and mechanical engineering applications. They are offered under the GNU General Public License and can be run, examined, shared and modified according to user’s requirements. SU2 and OpenFOAM are the two most popular open-source solvers in Computational Fluid Dynamics (CFD) community. In the present study, some passive control methods on the high-speed cavity flows are numerically simulated using these open-source flow solvers along with one commercial flow solver called ANSYS/Fluent. The results are compared with the available experimental data. The solver SU2 are seen to predict satisfactory the mean streamline velocity but not turbulent kinetic energy and overall averaged sound pressure level (OASPL). Whereas OpenFOAM predicts all these parameters nearly as the same levels of ANSYS/Fluent.

  5. Heavy Class Helicopter Fuselage Model Drag Reduction by Active Flow Control Systems

    Science.gov (United States)

    De Gregorio, F.

    2017-08-01

    A comprehensive experimental investigation of helicopter blunt fuselage drag reduction using active flow control is being carried out within the European Clean Sky program. The objective is to demonstrate the capability of several active flow technologies to decrease fuselage drag by alleviating the flow separation occurring in the rear area of some helicopters. The work is performed on a simplified blunt fuselage at model-scale. Two different flow control actuators are considered for evaluation: steady blowing, unsteady blowing (or pulsed jets). Laboratory tests of each individual actuator are first performed to assess their performance and properties. The fuselage model is then equipped with these actuators distributed in 3 slots located on the ramp bottom edge. This paper addresses the promising results obtained during the wind-tunnel campaign, since significant drag reductions are achieved for a wide range of fuselage angles of attack and yaw angles without detriment of the other aerodynamic characteristics.

  6. A Wavelet Neural Network Optimal Control Model for Traffic-Flow Prediction in Intelligent Transport Systems

    Science.gov (United States)

    Huang, Darong; Bai, Xing-Rong

    Based on wavelet transform and neural network theory, a traffic-flow prediction model, which was used in optimal control of Intelligent Traffic system, is constructed. First of all, we have extracted the scale coefficient and wavelet coefficient from the online measured raw data of traffic flow via wavelet transform; Secondly, an Artificial Neural Network model of Traffic-flow Prediction was constructed and trained using the coefficient sequences as inputs and raw data as outputs; Simultaneous, we have designed the running principium of the optimal control system of traffic-flow Forecasting model, the network topological structure and the data transmitted model; Finally, a simulated example has shown that the technique is effectively and exactly. The theoretical results indicated that the wavelet neural network prediction model and algorithms have a broad prospect for practical application.

  7. Parametric Approach to Assessing Performance of High-Lift Device Active Flow Control Architectures

    Directory of Open Access Journals (Sweden)

    Yu Cai

    2017-02-01

    Full Text Available Active Flow Control is at present an area of considerable research, with multiple potential aircraft applications. While the majority of research has focused on the performance of the actuators themselves, a system-level perspective is necessary to assess the viability of proposed solutions. This paper demonstrates such an approach, in which major system components are sized based on system flow and redundancy considerations, with the impacts linked directly to the mission performance of the aircraft. Considering the case of a large twin-aisle aircraft, four distinct active flow control architectures that facilitate the simplification of the high-lift mechanism are investigated using the demonstrated approach. The analysis indicates a very strong influence of system total mass flow requirement on architecture performance, both for a typical mission and also over the entire payload-range envelope of the aircraft.

  8. Flow restrictor silicon membrane microvalve actuated by optically controlled paraffin phase transition

    International Nuclear Information System (INIS)

    Kolari, K; Havia, T; Stuns, I; Hjort, K

    2014-01-01

    Restrictor valves allow proportional control of fluid flow but are rarely integrated in microfluidic systems. In this study, an optically actuated silicon membrane restrictor microvalve is demonstrated. Its actuation is based on the phase transition of paraffin, using a paraffin wax mixed with a suitable concentration of optically absorbing nanographite particles. Backing up the membrane with oil (the melted paraffin) allows for a compliant yet strong contact to the valve seat, which enables handling of high pressures. At flow rates up to 30 µL min −1 and at a pressure of 2 bars, the valve can successfully be closed and control the flow level by restriction. The use of this paraffin composite as an adhesive layer sandwiched between the silicon valve and glass eases fabrication. This type of restrictor valve is best suited for high pressure, low volume flow silicon-based nanofluidic systems. (paper)

  9. Effects of Active and Passive Control Techniques on Mach 1.5 Cavity Flow Dynamics

    Directory of Open Access Journals (Sweden)

    Selin Aradag

    2017-01-01

    Full Text Available Supersonic flow over cavities has been of interest since 1960s because cavities represent the bomb bays of aircraft. The flow is transient, turbulent, and complicated. Pressure fluctuations inside the cavity can impede successful weapon release. The objective of this study is to use active and passive control methods on supersonic cavity flow numerically to decrease or eliminate pressure oscillations. Jet blowing at several locations on the front and aft walls of the cavity configuration is used as an active control method. Several techniques are used for passive control including using a cover plate to separate the flow dynamics inside and outside of the cavity, trailing edge wall modifications, such as inclination of the trailing edge, and providing curvature to the trailing edge wall. The results of active and passive control techniques are compared with the baseline case in terms of pressure fluctuations, sound pressure levels at the leading edge, trailing edge walls, and cavity floor and in terms of formation of the flow structures and the results are presented. It is observed from the results that modification of the trailing edge wall is the most effective of the control methods tested leading to up to 40 dB reductions in cavity tones.

  10. A Flow Rate Control Approach on Off-Design Analysis of an Organic Rankine Cycle System

    Directory of Open Access Journals (Sweden)

    Ben-Ran Fu

    2016-09-01

    Full Text Available This study explored effects of off-design heat source temperature (TW,in or flow rate (mW on heat transfer characteristics and performance of an organic Rankine cycle system by controlling the flow rate of working fluid R245fa (i.e., the operation flow rate of R245fa was controlled to ensure that R245fa reached saturation liquid and vapor states at the outlets of the preheater and evaporator, respectively. The results showed that the operation flow rate of R245fa increased with TW,in or mW; higher TW,in or mW yielded better heat transfer performance of the designed preheater and required higher heat capacity of the evaporator; heat transfer characteristics of preheater and evaporator differed for off-design TW,in and mW; and net power output increased with TW,in or mW. The results further indicated that the control strategy should be different for various off-design conditions. Regarding maximum net power output, the flow rate control approach is optimal when TW,in or mW exceeds the design point, but the pressure control approach is better when TW,in or mW is lower than the design point.

  11. Energy Efficient Thermal Management for Natural Gas Engine Aftertreatment via Active Flow Control

    Energy Technology Data Exchange (ETDEWEB)

    David K. Irick; Ke Nguyen; Vitacheslav Naoumov; Doug Ferguson

    2006-04-01

    The project is focused on the development of an energy efficient aftertreatment system capable of reducing NOx and methane by 90% from lean-burn natural gas engines by applying active exhaust flow control. Compared to conventional passive flow-through reactors, the proposed scheme cuts supplemental energy by 50%-70%. The system consists of a Lean NOx Trap (LNT) system and an oxidation catalyst. Through alternating flow control, a major amount of engine exhaust flows through a large portion of the LNT system in the absorption mode, while a small amount of exhaust goes through a small portion of the LNT system in the regeneration or desulfurization mode. By periodically reversing the exhaust gas flow through the oxidation catalyst, a higher temperature profile is maintained in the catalyst bed resulting in greater efficiency of the oxidation catalyst at lower exhaust temperatures. The project involves conceptual design, theoretical analysis, computer simulation, prototype fabrication, and empirical studies. This report details the progress during the first twelve months of the project. The primary activities have been to develop the bench flow reactor system, develop the computer simulation and modeling of the reverse-flow oxidation catalyst, install the engine into the test cell, and begin design of the LNT system.

  12. Saturation flow versus green time at two-stage signal controlled intersections

    Directory of Open Access Journals (Sweden)

    A. Boumediene

    2009-12-01

    Full Text Available Intersections are the key components of road networks considerably affecting capacity. As flow levels and experience have increased over the years, methods and means have been developed to cope with growing demand for traffic at road junctions. Among various traffic control devices and techniques developed to cope with conflicting movements, traffic signals create artificial gaps to accommodate the impeded traffic streams. The majority of parameters that govern signalised intersection control and operations such as a degree of saturation, delays, queue lengths, the level of service etc. are very sensitive to saturation flow. Therefore, it is essential to reliably evaluate saturation flow for correctly setting traffic signals to avoid unnecessary delays and conflicts. Generally, almost all guidelines support the constancy of saturation flow irrespective of green time duration. This paper presents the results of field studies carried out to enable the performance of signalised intersections to be compared at different green time durations. It was found that saturation flow decreased slightly with growing green time. Reduction corresponded to between 2 and 5 pcus/gh per second of green time. However, the analyses of the discharge rate during the successive time intervals of 6-seconds showed a substantial reduction of 10% to 13% in saturation flow levels after 36 seconds of green time compared to those relating to 6–36 seconds range. No reduction in saturation flow levels was detected at the sites where only green periods of 44 seconds or less were implemented.

  13. Electrogates for stop-and-go control of liquid flow in microfluidics

    Science.gov (United States)

    Arango, Y.; Temiz, Y.; Gökçe, O.; Delamarche, E.

    2018-04-01

    Diagnostics based on microfluidic devices necessitate specific reagents, flow conditions, and kinetics for optimal performance. Such an optimization is often achieved using assay-specific microfluidic chip designs or systems with external liquid pumps. Here, we present "electrogates" for stop-and-go control of flow of liquids in capillary-driven microfluidic chips by combining liquid pinning and electrowetting. Electrogates are simple to fabricate and efficient: a sample pipetted to a microfluidic chip flows autonomously in 15-μm-deep hydrophilic channels until the liquid meniscus is pinned at the edge of a 1.5-μm-deep trench patterned at the bottom of a rectangular microchannel. The flow can then be resumed by applying a DC voltage between the liquid and the trench via integrated electrodes. Using a trench geometry with a semicircular shape, we show that retention times longer than 30 min are achieved for various aqueous solutions such as biological buffers, artificial urine, and human serum. We studied the activation voltage and activation delay of electrogates using a chip architecture having 6 independent flow paths and experimentally showed that the flow can be resumed in less than 1 s for voltages smaller than 10 V, making this technique compatible with low-power and portable microfluidic systems. Electrogates therefore can make capillary-driven microfluidic chips very versatile by adding flow control in microfluidic channels in a flexible manner.

  14. MODELING AND ANALYSIS OF UNSTEADY FLOW BEHAVIOR IN DEEPWATER CONTROLLED MUD-CAP DRILLING

    Directory of Open Access Journals (Sweden)

    Jiwei Li

    Full Text Available Abstract A new mathematical model was developed in this study to simulate the unsteady flow in controlled mud-cap drilling systems. The model can predict the time-dependent flow inside the drill string and annulus after a circulation break. This model consists of the continuity and momentum equations solved using the explicit Euler method. The model considers both Newtonian and non-Newtonian fluids flowing inside the drill string and annular space. The model predicts the transient flow velocity of mud, the equilibrium time, and the change in the bottom hole pressure (BHP during the unsteady flow. The model was verified using data from U-tube flow experiments reported in the literature. The result shows that the model is accurate, with a maximum average error of 3.56% for the velocity prediction. Together with the measured data, the computed transient flow behavior can be used to better detect well kick and a loss of circulation after the mud pump is shut down. The model sensitivity analysis show that the water depth, mud density and drill string size are the three major factors affecting the fluctuation of the BHP after a circulation break. These factors should be carefully examined in well design and drilling operations to minimize BHP fluctuation and well kick. This study provides the fundamentals for designing a safe system in controlled mud-cap drilling operati.

  15. Control volume based modelling in one space dimension of oscillating, compressible flow in reciprocating machines

    DEFF Research Database (Denmark)

    Andersen, Stig Kildegård; Carlsen, Henrik; Thomsen, Per Grove

    2006-01-01

    We present an approach for modelling unsteady, primarily one-dimensional, compressible flow. The conservation laws for mass, energy, and momentum are applied to a staggered mesh of control volumes and loss mechanisms are included directly as extra terms. Heat transfer, flow friction, and multidim...... are presented. The capabilities of the approach are illustrated with an example solution and an experimental validation of a Stirling engine model....

  16. The Effects of Sweeping Jet Actuator Parameters on Flow Separation Control

    Science.gov (United States)

    Koklu, Mehti

    2015-01-01

    A parametric experimental study was performed with sweeping jet actuators (fluidic oscillators) to determine their effectiveness in controlling flow separation on an adverse pressure gradient ramp. Actuator parameters that were investigated include blowing coefficients, operation mode, pitch and spreading angles, streamwise location, aspect ratio, and scale. Surface pressure measurements and surface oil flow visualization were used to characterize the effects of these parameters on the actuator performance. 2D Particle Image Velocimetry measurements of the flow field over the ramp and hot-wire measurements of the actuator's jet flow were also obtained for selective cases. In addition, the sweeping jet actuators were compared to other well-known flow control techniques such as micro-vortex generators, steady blowing, and steady vortex-generating jets. The results confirm that the sweeping jet actuators are more effective than steady blowing and steady vortex-generating jets. The results also suggest that an actuator with a larger spreading angle placed closer to the location where the flow separates provides better performance. For the cases tested, an actuator with an aspect ratio, which is the width/depth of the actuator throat, of 2 was found to be optimal. For a fixed momentum coefficient, decreasing the aspect ratio to 1 produced weaker vortices while increasing the aspect ratio to 4 reduced coverage area. Although scaling down the actuator (based on the throat dimensions) from 0.25 inch x 0.125 inch to 0.15 inch x 0.075 inch resulted in similar flow control performance, scaling down the actuator further to 0.075 inch x 0.0375 inch reduced the actuator efficiency by reducing the coverage area and the amount of mixing in the near-wall region. The results of this study provide insight that can be used to design and select the optimal sweeping jet actuator configuration for flow control applications.

  17. RANS Simulation of the Separated Flow over a Bump with Active Control

    Science.gov (United States)

    Iaccarino, Gianluca; Marongiu, Claudio; Catalano, Pietro; Amato, Marcello

    2003-01-01

    The objective of this paper is to investigate the accuracy of Reynolds-Averaged Navier- Stokes (RANS) techniques in predicting the effect of steady and unsteady flow control devices. This is part of a larger effort in applying numerical simulation tools to investigate of the performance of synthetic jets in high Reynolds number turbulent flows. RANS techniques have been successful in predicting isolated synthetic jets as reported by Kral et al. Nevertheless, due to the complex, and inherently unsteady nature of the interaction between the synthetic jet and the external boundary layer flow, it is not clear whether RANS models can represent the turbulence statistics correctly.

  18. Validation of CFD predictions using process data obtained from flow through an industrial control valve

    International Nuclear Information System (INIS)

    Green, J; Mishra, R; Charlton, M; Owen, R

    2012-01-01

    This study uses the experimental flow test data to validate CFD simulations for a complex control valve trim. In both the simulation and the experimental flow test the capacity of the trim (Cv) is calculated in order to test the ability of CFD software to provide a design tool for these trims. While CFD tests produced results for the capacity which were consistent across a series of five different simulations, it differed from the experimental flow data by nearly 25%. This indicates that CFD simulations need to be properly calibrated before being used in designing complex valve trims.

  19. An Autonomous Sensor System Architecture for Active Flow and Noise Control Feedback

    Science.gov (United States)

    Humphreys, William M, Jr.; Culliton, William G.

    2008-01-01

    Multi-channel sensor fusion represents a powerful technique to simply and efficiently extract information from complex phenomena. While the technique has traditionally been used for military target tracking and situational awareness, a study has been successfully completed that demonstrates that sensor fusion can be applied equally well to aerodynamic applications. A prototype autonomous hardware processor was successfully designed and used to detect in real-time the two-dimensional flow reattachment location generated by a simple separated-flow wind tunnel model. The success of this demonstration illustrates the feasibility of using autonomous sensor processing architectures to enhance flow control feedback signal generation.

  20. Control of Flowing Liquid Films By Electrostatic Fields in Space

    Science.gov (United States)

    Bankoff, S. George; Miksis, Michael J.; Kim, Hyo

    1996-01-01

    A novel type of lightweight space radiator has been proposed which employs internal electrostatic fields to stop coolant leaks from punctures caused by micrometeorites or space debris. Extensive calculations have indicated the feasibility of leak stoppage without film destabilization for both stationary and rotating designs. Solutions of the evolution equation for a liquid-metal film on an inclined plate, using lubrication theory for low Reynolds numbers, Karman-Pohlhausen quadratic velocity profiles for higher Reynolds numbers, and a direct numerical solution are shown. For verification an earth-based falling-film experiment on a precisely-vertical wall with controllable vacuum on either side of a small puncture is proposed. The pressure difference required to start and to stop the leak, in the presence and absence of a strong electric field, will be measured and compared with calculations. Various parameters, such as field strength, film Reynolds number, contact angle, and hole diameter will be examined. A theoretical analysis will be made of the case where the electrode is close enough to the film surface that the electric field equation and the surface dynamics equations are coupled. Preflight design calculations will be made in order to transfer the modified equipment to a flight experiment.

  1. Preventive Security-Constrained Optimal Power Flow Considering UPFC Control Modes

    Directory of Open Access Journals (Sweden)

    Xi Wu

    2017-08-01

    Full Text Available The successful application of the unified power flow controller (UPFC provides a new control method for the secure and economic operation of power system. In order to make the full use of UPFC and improve the economic efficiency and static security of a power system, a preventive security-constrained power flow optimization method considering UPFC control modes is proposed in this paper. Firstly, an iterative method considering UPFC control modes is deduced for power flow calculation. Taking into account the influence of different UPFC control modes on the distribution of power flow after N-1 contingency, the optimization model is then constructed by setting a minimal system operation cost and a maximum static security margin as the objective. Based on this model, the particle swarm optimization (PSO algorithm is utilized to optimize power system operating parameters and UPFC control modes simultaneously. Finally, a standard IEEE 30-bus system is utilized to demonstrate that the proposed method fully exploits the potential of static control of UPFC and significantly increases the economic efficiency and static security of the power system.

  2. Control of Networked Traffic Flow Distribution - A Stochastic Distribution System Perspective

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hong [Pacific Northwest National Laboratory (PNNL); Aziz, H M Abdul [ORNL; Young, Stan [National Renewable Energy Laboratory (NREL); Patil, Sagar [Pacific Northwest National Laboratory (PNNL)

    2017-10-01

    Networked traffic flow is a common scenario for urban transportation, where the distribution of vehicle queues either at controlled intersections or highway segments reflect the smoothness of the traffic flow in the network. At signalized intersections, the traffic queues are controlled by traffic signal control settings and effective traffic lights control would realize both smooth traffic flow and minimize fuel consumption. Funded by the Energy Efficient Mobility Systems (EEMS) program of the Vehicle Technologies Office of the US Department of Energy, we performed a preliminary investigation on the modelling and control framework in context of urban network of signalized intersections. In specific, we developed a recursive input-output traffic queueing models. The queue formation can be modeled as a stochastic process where the number of vehicles entering each intersection is a random number. Further, we proposed a preliminary B-Spline stochastic model for a one-way single-lane corridor traffic system based on theory of stochastic distribution control.. It has been shown that the developed stochastic model would provide the optimal probability density function (PDF) of the traffic queueing length as a dynamic function of the traffic signal setting parameters. Based upon such a stochastic distribution model, we have proposed a preliminary closed loop framework on stochastic distribution control for the traffic queueing system to make the traffic queueing length PDF follow a target PDF that potentially realizes the smooth traffic flow distribution in a concerned corridor.

  3. Separation Dynamics of Controlled Internal Flow in an Adverse Pressure Gradient

    Science.gov (United States)

    Peterson, C. J.; Vukasinovic, B.; Glezer, A.

    2017-11-01

    The effects of fluidic actuation on the dynamic evolution of aggressive internal flow separation is investigated at speeds up to M = 0.4 within a constant-width diffuser branching off of a primary flow duct. It is shown that a spanwise array of fluidic actuators upstream of the separation actively controls the flow constriction (and losses) within the diffuser and consequently the local pressure gradient at its entrance. The effectiveness of the actuation, as may be measured by the increased flow rate that is diverted through the diffuser, scales with its flow rate coefficient. In the presence of actuation (0.7% mass fraction), the mass flow rate in the primary duct increases by 10% while the fraction of the diverted mass flow rate in the diffuser increases by more than 45%. The flow dynamics near separation in the absence and presence of actuation are characterized using high speed particle image velocimetry and analyzed using proper orthogonal and spectral decompositions. In particular, the spectral contents of the incipient boundary layer separation are compared in the absence and presence of actuation with emphasis on the changes in local dynamics near separation as the characteristic cross stream scale of the boundary layer increases with separation delay.

  4. Improved coal grinding and fuel flow control in thermal power plants

    DEFF Research Database (Denmark)

    Niemczyk, Piotr; Bendtsen, Jan Dimon

    2011-01-01

    A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated in the m......A novel controller for coal circulation and pulverized coal flow in a coal mill is proposed. The design is based on optimal control theory for bilinear systems with additional integral action. The states are estimated from the grinding power consumption and the amount of coal accumulated...... as well as when parameter uncertainties and noise are present. The proposed controller lowers the grinding power consumption while in most cases exhibiting superior performance in comparison with the PID controller....

  5. Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control

    International Nuclear Information System (INIS)

    Yu-Liang, Liu; Jie, Zhu; Xiao-Shu, Luo

    2009-01-01

    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, the effectiveness and feasibility of the novel model in internet congestion control are verified

  6. Bifurcation and stability of an improved time-delayed fluid flow model in internet congestion control

    Science.gov (United States)

    Liu, Yu-Liang; Zhu, Jie; Luo, Xiao-Shu

    2009-09-01

    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, the effectiveness and feasibility of the novel model in internet congestion control are verified.

  7. Unified Power Flow Controller Placement to Improve Damping of Power Oscillations

    OpenAIRE

    M. Salehi; A. A. Motie Birjandi; F. Namdari

    2015-01-01

    Weak damping of low frequency oscillations is a frequent phenomenon in electrical power systems. These frequencies can be damped by power system stabilizers. Unified power flow controller (UPFC), as one of the most important FACTS devices, can be applied to increase the damping of power system oscillations and the more effect of this controller on increasing the damping of oscillations depends on its proper placement in power systems. In this paper, a technique based on controllability is pro...

  8. Perspective on traffic control : Aspects of freeway control, intersection control and the control of transit flow in the Netherlands

    NARCIS (Netherlands)

    Hakkesteegt, P.

    1988-01-01

    Paper presented at the 1988 TRB Annual Meeting, Washington D.C., USA. The first part of this paper deals with the control and signalling system for motorways, directed to a more efficient use of available road capacity and to the improvement of road safety. The second part gives some insight into

  9. Helicopter Fuselage Active Flow Control in the Presence of a Rotor

    Science.gov (United States)

    Martin, Preston B; Overmeyer, Austin D.; Tanner, Philip E.; Wilson, Jacob S.; Jenkins, Luther N.

    2014-01-01

    This work extends previous investigations of active flow control for helicopter fuselage drag and download reduction to include the effects of the rotor. The development of the new wind tunnel model equipped with fluidic oscillators is explained in terms of the previous test results. Large drag reductions greater than 20% in some cases were measured during powered testing without increasing, and in some cases decreasing download in forward flight. As confirmed by Particle Image Velocimetry (PIV), the optimum actuator configuration that provided a decrease in both drag and download appeared to create a virtual (fluidic) boat-tail fairing instead of attaching flow to the ramp surface. This idea of a fluidic fairing shifts the focus of 3D separation control behind bluff bodies from controlling/reattaching surface boundary layers to interacting with the wake flow.

  10. Flow control and routing techniques for integrated voice and data networks

    Science.gov (United States)

    Ibe, O. C.

    1981-10-01

    We consider a model of integrated voice and data networks. In this model the network flow problem is formulated as a convex optimization problem. The objective function comprises two types of cost functions: the congestion cost functions, which limit the average input traffic to values compatible with the network conditions; and the rate limitation cost functions, which ensure that all conversations are fairly treated. A joint flow control and routing algorithm is constructed which determines the routes for each conversation, and effects flow control by setting voice packet lengths and data input rates in a manner that achieves optimal tradeoff between each user's satisfaction and the cost of network congestion. An additional congestion control protocol is specified which could be used in conjunction with the algorithm to make the latter respond more dynamically to network congestion.

  11. Modeling Cerebral Blood Flow Control During Posture Change from Sitting to Standing

    DEFF Research Database (Denmark)

    Olufsen, Mette; Tran, Hien; Ottesen, Johnny T.

    2004-01-01

    , the heart, and venous valves. We use physiologically based control mechanisms to describe the regulation of cerebral blood velocity and arterial pressure in response to orthostatic hypotension resulting from postural change. Beyond active control mechanisms we also have to include certain passive non......Hypertension, decreased cerebral blood flow, and diminished cerebral blood flow regulation, are among the first signs indicating the presence of cerebral vascular disease. In this paper, we will present a mathematical model that can predict blood flow and pressure during posture change from sitting......-linearities in some of the compliance-pressure and resistance-pressure relationships. Futhermore, an acurate and physiologically based submodel, describing the dynamics of how gravity effects the blood distribution during suspine changes, is included. To justify the fidelity of our mathematical model and control...

  12. Separation flow control on a generic ground vehicle using steady microjet arrays

    Energy Technology Data Exchange (ETDEWEB)

    Aubrun, Sandrine; Kourta, Azeddine [Universite d' Orleans, Laboratoire PRISME, Orleans cedex (France); McNally, Jonathan; Alvi, Farrukh [Florida State University, FAMU-FSU College of Engineering, Tallahassee, FL (United States)

    2011-11-15

    A model of a generic vehicle shape, the Ahmed body with a 25 slant, is equipped with an array of blowing steady microjets 6 mm downstream of the separation line between the roof and the slanted rear window. The goal of the present study is to evaluate the effectiveness of this actuation method in reducing the aerodynamic drag, by reducing or suppressing the 3D closed separation bubble located on the slanted surface. The efficiency of this control approach is quantified with the help of aerodynamic load measurements. The changes in the flow field when control is applied are examined using PIV and wall pressure measurements and skin friction visualisations. By activating the steady microjet array, the drag coefficient was reduced by 9-14% and the lift coefficient up to 42%, depending on the Reynolds number. The strong modification of the flow topology under progressive flow control is particularly studied. (orig.)

  13. Numerical study of flow control strategies for a simplified square back ground vehicle

    Energy Technology Data Exchange (ETDEWEB)

    Eulalie, Yoann; Gilotte, Philippe [Plastic Omnium, Avenue du bois des vergnes, F-01150 Sainte-Julie (France); Mortazavi, Iraj, E-mail: iraj.mortazavi@cnam.fr [Team M2N, CNAM Paris, 292 Rue St. Martin, 75003 Paris (France)

    2017-06-15

    Current automotive trends lead to vertical shapes in the region of the rear tailgates, which induce high aerodynamical losses at the rear wall of vehicles. It is therefore important to work on turbulent wake in order to find drag reduction solutions for the current vehicle design. This paper focuses on flow control strategies, which are designed to interact with shear layers backward from the detachment region, in order to increase pressure values in the wake of a square back bluff body. This study involves large eddy simulation results validated by experimental data. After the first section, which represents experimental validation of LES computations with and without active flow control on an Ahmed bluff body, we will present a wide range of numerical results describing several active and passive flow control solutions leading to drag reductions of up to 10%. The last part of this paper will focus on some fluid mechanisms, which could explain these aerodynamical performances. (paper)

  14. Numerical study of flow control strategies for a simplified square back ground vehicle

    International Nuclear Information System (INIS)

    Eulalie, Yoann; Gilotte, Philippe; Mortazavi, Iraj

    2017-01-01

    Current automotive trends lead to vertical shapes in the region of the rear tailgates, which induce high aerodynamical losses at the rear wall of vehicles. It is therefore important to work on turbulent wake in order to find drag reduction solutions for the current vehicle design. This paper focuses on flow control strategies, which are designed to interact with shear layers backward from the detachment region, in order to increase pressure values in the wake of a square back bluff body. This study involves large eddy simulation results validated by experimental data. After the first section, which represents experimental validation of LES computations with and without active flow control on an Ahmed bluff body, we will present a wide range of numerical results describing several active and passive flow control solutions leading to drag reductions of up to 10%. The last part of this paper will focus on some fluid mechanisms, which could explain these aerodynamical performances. (paper)

  15. A New Real Time Lyapunov Based Controller for Power Quality Improvement in Unified Power Flow Controllers Using Direct Matrix Converters

    Directory of Open Access Journals (Sweden)

    Joaquim Monteiro

    2017-06-01

    Full Text Available This paper proposes a Direct Matrix Converter operating as a Unified Power Flow Controller (DMC-UPFC with an advanced control method for UPFC, based on the Lyapunov direct method, presenting good results in power quality assessment. This control method is used for real-time calculation of the appropriate matrix switching state, determining which switching state should be applied in the following sampling period. The control strategy takes into account active and reactive power flow references to choose the vector converter closest to the optimum. Theoretical principles for this new real-time vector modulation and control applied to the DMC-UPFC with input filter are established. The method needs DMC-UPFC dynamic equations to be solved just once in each control cycle, to find the required optimum vector, in contrast to similar control methods that need 27 vector estimations per control cycle. The designed controller’s performance was evaluated using Matlab/Simulink software. Controllers were also implemented using a digital signal processing (DSP system and matrix hardware. Simulation and experimental results show decoupled transmission line active (P and reactive (Q power control with zero theoretical error tracking and fast response. Output currents and voltages show small ripple and low harmonic content.

  16. Control Theoretic Modeling and Generated Flow Patterns of a Fish-Tail Robot

    Science.gov (United States)

    Massey, Brian; Morgansen, Kristi; Dabiri, Dana

    2003-11-01

    Many real-world engineering problems involve understanding and manipulating fluid flows. One of the challenges to further progress in the area of active flow control is the lack of appropriate models that are amenable to control-theoretic studies and algorithm design and also incorporate reasonably realistic fluid dynamic effects. We focus here on modeling and model-verification of bio-inspired actuators (fish-fin type structures) used to control fluid dynamic artifacts that will affect speed, agility, and stealth of Underwater Autonomous Vehicles (UAVs). Vehicles using fish-tail type systems are more maneuverable, can turn in much shorter and more constrained spaces, have lower drag, are quieter and potentially more efficient than those using propellers. We will present control-theoretic models for a simple prototype coupled fluid and mechanical actuator where fluid effects are crudely modeled by assuming only lift, drag, and added mass, while neglecting boundary effects. These models will be tested with different control input parameters on an experimental fish-tail robot with the resulting flow captured with DPIV. Relations between the model, the control function choices, the obtained thrust and drag, and the corresponding flow patterns will be presented and discussed.

  17. Application of Newton's optimal power flow in voltage/reactive power control

    Energy Technology Data Exchange (ETDEWEB)

    Bjelogrlic, M.; Babic, B.S. (Electric Power Board of Serbia, Belgrade (YU)); Calovic, M.S. (Dept. of Electrical Engineering, University of Belgrade, Belgrade (YU)); Ristanovic, P. (Institute Nikola Tesla, Belgrade (YU))

    1990-11-01

    This paper considers an application of Newton's optimal power flow to the solution of the secondary voltage/reactive power control in transmission networks. An efficient computer program based on the latest achievements in the sparse matrix/vector techniques has been developed for this purpose. It is characterized by good robustness, accuracy and speed. A combined objective function appropriate for various system load levels with suitable constraints, for treatment of the power system security and economy is also proposed. For the real-time voltage/reactive power control, a suboptimal power flow procedure has been derived by using the reduced set of control variables. This procedure is based on the sensitivity theory applied to the determination of zones for the secondary voltage/reactive power control and corresponding reduced set of regulating sources, whose reactive outputs represent control variables in the optimal power flow program. As a result, the optimal power flow program output becomes a schedule to be used by operators in the process of the real-time voltage/reactive power control in both normal and emergency operating states.

  18. The effects of surface topography control using liquid crystal elastomers on bodies in flow

    Science.gov (United States)

    Settle, Michael; Guin, Tyler; Beblo, Richard; White, Timothy; Reich, Gregory

    2018-03-01

    Surface topography control has use across many applications including delayed separation of flow via selective boundary-layer tripping. Recently, advances with liquid crystal elastomers (LCE) have been leveraged for controlled, repeatable, out-of-plane deformations that could enable these topographical changes. An aligned LCE deforms when heated, associated with a loss in order. Circumferential patterns fabricated through the thickness of the LCE film yield a predictable conical out-of-plane deformation that can control surface topography. This study focuses on the experimental investigation of LCE behavior for flow control. Initially, the deformations of LCE samples 1/2" in diameter and 50 µm thick were characterized using Digital Image Correlation under uniform positive and negative gauge pressures at various temperatures. Surface topography showed strong dependence on boundary conditions, sample dimensions, and pattern location relative to the applied boundary conditions, informing adjustment of the LCE of the chemistry to produce higher modulus and glassy materials. As an initial demonstration of the ability to control flow, Then, to demonstrate the potential for flow control, 3D printed cylinders with varying arrangements of representative topographical features were characterized in a wind tunnel with Particle Image Velocimetry. Results showed that features with a maximum deflection height of 1.5 mm in a two-row arrangement can form an asymmetric wake about a 73 mm diameter cylinder that reduces drag while generating lift. These results inform subsequent investigation of active LCE elements on a cylinder that are currently under examination.

  19. DC Voltage Droop Control Implementation in the AC/DC Power Flow Algorithm: Combinational Approach

    DEFF Research Database (Denmark)

    Akhter, F.; Macpherson, D.E.; Harrison, G.P.

    2015-01-01

    of operational flexibility, as more than one VSC station controls the DC link voltage of the MTDC system. This model enables the study of the effects of DC droop control on the power flows of the combined AC/DC system for steady state studies after VSC station outages or transient conditions without needing...... to use its complete dynamic model. Further, the proposed approach can be extended to include multiple AC and DC grids for combined AC/DC power flow analysis. The algorithm is implemented by modifying the MATPOWER based MATACDC program and the results shows that the algorithm works efficiently....

  20. Countercurrent flow-limiting characteristics of a Savannah River Plant control rod septifoil

    International Nuclear Information System (INIS)

    Anderson, J.L.

    1992-07-01

    Experiments were performed at the Idaho National Engineering Laboratory to investigate the counter-current flow limiting characteristics of a Savannah River Plant control rod septifoil assembly. These experiments were unheated, using air and water as the working fluids. Results are presented in terms of the Wallis flooding correlation for several different control rod configurations. Flooding was observed to occur in the vicinity of the inlet slots/holes of the septifoil, rather than within the rod bundle at the location of the minimum flow area. Nearly identical flooding characteristics of the septifoil were observed for configurations with zero, three, and four rods inserted, but significantly different results occurred with 5 rods inserted

  1. Nonlinear Power Flow Control Design Utilizing Exergy, Entropy, Static and Dynamic Stability, and Lyapunov Analysis

    CERN Document Server

    Robinett III, Rush D

    2011-01-01

    Nonlinear Powerflow Control Design presents an innovative control system design process motivated by renewable energy electric grid integration problems. The concepts developed result from the convergence of three research and development goals: • to create a unifying metric to compare the value of different energy sources – coal-burning power plant, wind turbines, solar photovoltaics, etc. – to be integrated into the electric power grid and to replace the typical metric of costs/profit; • to develop a new nonlinear control tool that applies power flow control, thermodynamics, and complex adaptive systems theory to the energy grid in a consistent way; and • to apply collective robotics theories to the creation of high-performance teams of people and key individuals in order to account for human factors in controlling and selling power into a distributed, decentralized electric power grid. All three of these goals have important concepts in common: exergy flow, limit cycles, and balance between compe...

  2. Optimal Control of Partially Miscible Two-Phase Flow with Applications to Subsurface CO2 Sequestration

    KAUST Repository

    Simon, Moritz; Ulbrich, Michael

    2013-01-01

    Motivated by applications in subsurface CO2 sequestration, we investigate constrained optimal control problems with partially miscible two-phase flow in porous media. The objective is, e.g., to maximize the amount of trapped CO2 in an underground reservoir after a fixed period of CO2 injection, where the time-dependent injection rates in multiple wells are used as control parameters. We describe the governing two-phase two-component Darcy flow PDE system and formulate the optimal control problem. For the discretization we use a variant of the BOX method, a locally conservative control-volume FE method. The timestep-wise Lagrangian of the control problem is implemented as a functional in the PDE toolbox Sundance, which is part of the HPC software Trilinos. The resulting MPI parallelized Sundance state and adjoint solvers are linked to the interior point optimization package IPOPT. Finally, we present some numerical results in a heterogeneous model reservoir.

  3. Ways and possibilities of controlling turbulent shear flows - A selection of problems pursued at HFI and DLR in Berlin

    Science.gov (United States)

    Fiedler, Heinrich E.

    1991-01-01

    Recent works on flow stability and turbulence are reviewed with emphasis on the flow control of free and wall-bounded flows. Axisymmetric jets in counterflow are considered for two characteristic cases: a stable case at low velocity ratios and an unstable case at higher velocity ratios. Among mixing layers, excited layers are covered as well as density-inhomogeneous flows, where countergradient, homogeneous, and cogradient cases are reviewed. The influences of boundary conditions are analyzed, and focus is placed on feedback condition, flow distortion, accelerated flow, and two- and three-dimensional studies. Attention is given to stability investigations and riblets as a means for reducing surface friction in a turbulent flow.

  4. CFD Simulations of a Finned Projectile with Microflaps for Flow Control

    Directory of Open Access Journals (Sweden)

    Jubaraj Sahu

    2017-01-01

    Full Text Available This research describes a computational study undertaken to determine the effect of a flow control mechanism and its associated aerodynamics for a finned projectile. The flow control system consists of small microflaps located between the rear fins of the projectile. These small microflaps alter the flow field in the aft finned region of the projectile, create asymmetric pressure distributions, and thus produce aerodynamic control forces and moments. A number of different geometric parameters, microflap locations, and the number of microflaps were varied in an attempt to maximize the control authority generated by the flaps. Steady-state Navier-Stokes computations were performed to obtain the control aerodynamic forces and moments associated with the microflaps. These results were used to optimize the control authority at a supersonic speed, M=2.5. Computed results showed not only the microflaps to be effective at this speed, but also configurations with 6 and 8 microflaps were found to generate 25%–50% more control force than a baseline 4-flap configuration. These results led to a new optimized 8-flap configuration that was further investigated for a range of Mach numbers from M=0.8 to 5.0 and was found to be a viable configuration effective in providing control at all of these speeds.

  5. Surface Patterning: Controlling Fluid Flow Through Dolphin and Shark Skin Biomimicry

    Science.gov (United States)

    Gamble, Lawren; Lang, Amy; Bradshaw, Michael; McVay, Eric

    2013-11-01

    Dolphin skin is characterized by circumferential ridges, perpendicular to fluid flow, present from the crest of the head until the tail fluke. When observing a cross section of skin, the ridges have a sinusoidal pattern. Sinusoidal grooves have been proven to induce vortices in the cavities that can help control flow separation which can reduce pressure drag. Shark skin, however, is patterned with flexible scales that bristle up to 50 degrees with reversed flow. Both dolphin ridges and shark scales are thought to help control fluid flow and increase swimming efficiency by delaying the separation of the boundary layer. This study investigates how flow characteristics can be altered with bio-inspired surface patterning. A NACA 4412 hydrofoil was entirely patterned with transverse sinusoidal grooves, inspired by dolphin skin but scaled so the cavities on the model have the same Reynolds number as the cavities on a swimming shark. Static tests were conducted at a Reynolds number of approximately 100,000 and at varying angles of attack. The results were compared to the smooth hydrofoil case. The flow data was quantified using Digital Particle Image Velocimetry (DPIV). The results of this study demonstrated that the patterned hydrofoil experienced greater separation than the smooth hydrofoil. It is hypothesize that this could be remediated if the pattern was placed only after the maximum thickness of the hydrofoil. Funding through NSF REU grant 1062611 is gratefully acknowledged.

  6. The Dynamics of Controlled Flow Separation within a Diverter Duct Diffuser

    Science.gov (United States)

    Peterson, C. J.; Vukasinovic, B.; Glezer, A.

    2016-11-01

    The evolution and receptivity to fluidic actuation of the flow separation within a rectangular, constant-width, diffuser that is branched off of a primary channel is investigated experimentally at speeds up to M = 0.4. The coupling between the diffuser's adverse pressure gradient and the internal separation that constricts nearly half of the flow passage through the duct is controlled using a spanwise array of fluidic actuators on the surface upstream of the diffuser's inlet plane. The dynamics of the separating surface vorticity layer in the absence and presence of actuation are investigated using high-speed particle image velocimetry combined with surface pressure measurements and total pressure distributions at the primary channel's exit plane. It is shown that the actuation significantly alters the incipient dynamics of the separating vorticity layer as the characteristic cross stream scales of the boundary layer upstream of separation and of the ensuing vorticity concentrations within the separated flow increase progressively with actuation level. It is argued that the dissipative (high frequency) actuation alters the balance between large- and small-scale motions near separation by intensifying the large-scale motions and limiting the small-scale dynamics. Controlling separation within the diffuser duct also has a profound effect on the global flow. In the presence of actuation, the mass flow rate in the primary duct increases 10% while the fraction of the diverted mass flow rate in the diffuser increases by more than 45% at 0.7% actuation mass fraction. Supported by the Boeing Company.

  7. Experimental Investigation of the Compressor Cascade under an Active Flow Control

    Directory of Open Access Journals (Sweden)

    Lukáč J.

    2013-04-01

    Full Text Available The paper is concerned with flow past compressor blade cascade (NACA 65 with thickened trailing edge at off-design regimes, which are characteristic by partial or complete flow separation on the suction surface of the blades. An attempt has been made to moderate the flow separation using continuous or periodic blowing from the sidewalls. The flow field was visualized using schlieren technique and surface paint visualization. The visualizations were complemented by measurement of the static pressure distribution on the suction surface of the blades. In agreement with the literature, the visualizations confirmed a complexity of the 3-dimensional flow separation, which was intensified by influence of the sidewall boundary layers developing from upstream parts of the test section. Furthermore, it was found out that the effect of both continuous and periodic blowing was rather minor. Finally, the results agree with the available literature showing that it is highly difficult to considerably control the complex 3-dimensional flow separation in the compressor cascade by control jets issuing (only from the sidewalls

  8. Physically consistent data assimilation method based on feedback control for patient-specific blood flow analysis.

    Science.gov (United States)

    Ii, Satoshi; Adib, Mohd Azrul Hisham Mohd; Watanabe, Yoshiyuki; Wada, Shigeo

    2018-01-01

    This paper presents a novel data assimilation method for patient-specific blood flow analysis based on feedback control theory called the physically consistent feedback control-based data assimilation (PFC-DA) method. In the PFC-DA method, the signal, which is the residual error term of the velocity when comparing the numerical and reference measurement data, is cast as a source term in a Poisson equation for the scalar potential field that induces flow in a closed system. The pressure values at the inlet and outlet boundaries are recursively calculated by this scalar potential field. Hence, the flow field is physically consistent because it is driven by the calculated inlet and outlet pressures, without any artificial body forces. As compared with existing variational approaches, although this PFC-DA method does not guarantee the optimal solution, only one additional Poisson equation for the scalar potential field is required, providing a remarkable improvement for such a small additional computational cost at every iteration. Through numerical examples for 2D and 3D exact flow fields, with both noise-free and noisy reference data as well as a blood flow analysis on a cerebral aneurysm using actual patient data, the robustness and accuracy of this approach is shown. Moreover, the feasibility of a patient-specific practical blood flow analysis is demonstrated. Copyright © 2017 John Wiley & Sons, Ltd.

  9. Research on Segmentation Monitoring Control of IA-RWA Algorithm with Probe Flow

    Science.gov (United States)

    Ren, Danping; Guo, Kun; Yao, Qiuyan; Zhao, Jijun

    2018-04-01

    The impairment-aware routing and wavelength assignment algorithm with probe flow (P-IA-RWA) can make an accurate estimation for the transmission quality of the link when the connection request comes. But it also causes some problems. The probe flow data introduced in the P-IA-RWA algorithm can result in the competition for wavelength resources. In order to reduce the competition and the blocking probability of the network, a new P-IA-RWA algorithm with segmentation monitoring-control mechanism (SMC-P-IA-RWA) is proposed. The algorithm would reduce the holding time of network resources for the probe flow. It segments the candidate path suitably for the data transmitting. And the transmission quality of the probe flow sent by the source node will be monitored in the endpoint of each segment. The transmission quality of data can also be monitored, so as to make the appropriate treatment to avoid the unnecessary probe flow. The simulation results show that the proposed SMC-P-IA-RWA algorithm can effectively reduce the blocking probability. It brings a better solution to the competition for resources between the probe flow and the main data to be transferred. And it is more suitable for scheduling control in the large-scale network.

  10. Plasma-based actuators for turbulent boundary layer control in transonic flow

    Science.gov (United States)

    Budovsky, A. D.; Polivanov, P. A.; Vishnyakov, O. I.; Sidorenko, A. A.

    2017-10-01

    The study is devoted to development of methods for active control of flow structure typical for the aircraft wings in transonic flow with turbulent boundary layer. The control strategy accepted in the study was based on using of the effects of plasma discharges interaction with miniature geometrical obstacles of various shapes. The conceptions were studied computationally using 3D RANS, URANS approaches. The results of the computations have shown that energy deposition can significantly change the flow pattern over the obstacles increasing their influence on the flow in boundary layer region. Namely, one of the most interesting and promising data were obtained for actuators basing on combination of vertical wedge with asymmetrical plasma discharge. The wedge considered is aligned with the local streamlines and protruding in the flow by 0.4-0.8 of local boundary layer thickness. The actuator produces negligible distortion of the flow at the absence of energy deposition. Energy deposition along the one side of the wedge results in longitudinal vortex formation in the wake of the actuator providing momentum exchange in the boundary layer. The actuator was manufactured and tested in wind tunnel experiments at Mach number 1.5 using the model of flat plate. The experimental data obtained by PIV proved the availability of the actuator.

  11. Control-volume-based model of the steam-water injector flow

    Science.gov (United States)

    Kwidziński, Roman

    2010-03-01

    The paper presents equations of a mathematical model to calculate flow parameters in characteristic cross-sections in the steam-water injector. In the model, component parts of the injector (steam nozzle, water nozzle, mixing chamber, condensation wave region, diffuser) are treated as a series of connected control volumes. At first, equations for the steam nozzle and water nozzle are written and solved for known flow parameters at the injector inlet. Next, the flow properties in two-phase flow comprising mixing chamber and condensation wave region are determined from mass, momentum and energy balance equations. Then, water compression in diffuser is taken into account to evaluate the flow parameters at the injector outlet. Irreversible losses due to friction, condensation and shock wave formation are taken into account for the flow in the steam nozzle. In two-phase flow domain, thermal and mechanical nonequilibrium between vapour and liquid is modelled. For diffuser, frictional pressure loss is considered. Comparison of the model predictions with experimental data shows good agreement, with an error not exceeding 15% for discharge (outlet) pressure and 1 K for outlet temperature.

  12. A review of wind turbine-oriented active flow control strategies

    Science.gov (United States)

    Aubrun, Sandrine; Leroy, Annie; Devinant, Philippe

    2017-10-01

    To reduce the levelized cost of energy, the energy production, robustness and lifespan of horizontal axis wind turbines (HAWTs) have to be improved to ensure optimal energy production and operational availability during periods longer than 15-20 years. HAWTs are subject to unsteady wind loads that generate combinations of unsteady mechanical loads with characteristic time scales from seconds to minutes. This can be reduced by controlling the aerodynamic performance of the wind turbine rotors in real time to compensate the overloads. Mitigating load fluctuations and optimizing the aerodynamic performance at higher time scales need the development of fast-response active flow control (AFC) strategies located as close as possible to the torque generation, i.e., directly on the blades. The most conventional actuators currently used in HAWTs are mechanical flaps/tabs (similar to aeronautical accessories), but some more innovative concepts based on fluidic and plasma actuators are very promising since they are devoid of mechanical parts, have a fast response and can be driven in unsteady modes to influence natural instabilities of the flow. In this context, the present paper aims at giving a state-of-the-art review of current research in wind turbine-oriented flow control strategies applied at the blade scale. It provides an overview of research conducted in the last decade dealing with the actuators and devices devoted to developing AFC on rotor blades, focusing on the flow phenomena that they cause and that can lead to aerodynamic load increase or decrease. After providing some general background on wind turbine blade aerodynamics and on the atmospheric flows in which HAWTs operate, the review focuses on flow separation control and circulation control mainly through experimental investigations. It is followed by a discussion about the overall limitations of current studies in the wind energy context, with a focus on a few studies that attempt to provide a global

  13. Design of a high-lift experiment in water including active flow control

    International Nuclear Information System (INIS)

    Beutel, T; Schwerter, M; Büttgenbach, S; Leester-Schädel, M; Sattler, S; El Sayed, Y; Radespiel, R; Zander, M; Sinapius, M; Wierach, P

    2014-01-01

    This paper describes the structural design of an active flow-control experiment. The aim of the experiment is to investigate the increase in efficiency of an internally blown Coanda flap using unsteady blowing. The system uses tailor-made microelectromechanical (MEMS) pressure sensors to determine the state of the oncoming flow and an actuated lip to regulate the mass flow and velocity of a stream near a wall over the internally blown flap. Sensors and actuators are integrated into a highly loaded system that is extremely compact. The sensors are connected to a bus system that feeds the data into a real-time control system. The piezoelectric actuators using the d 33 effect at a comparable low voltage of 120 V are integrated into a lip that controls the blowout slot height. The system is designed for closed-loop control that efficiently avoids flow separation on the Coanda flap. The setup is designed for water-tunnel experiments in order to reduce the free-stream velocity and the system’s control frequency by a factor of 10 compared with that in air. This paper outlines the function and verification of the system’s main components and their development. (technical note)

  14. Numerical Modeling of Cavitating Venturi: A Flow Control Element of Propulsion System

    Science.gov (United States)

    Majumdar, Alok; Saxon, Jeff (Technical Monitor)

    2002-01-01

    In a propulsion system, the propellant flow and mixture ratio could be controlled either by variable area flow control valves or by passive flow control elements such as cavitating venturies. Cavitating venturies maintain constant propellant flowrate for fixed inlet conditions (pressure and temperature) and wide range of outlet pressures, thereby maintain constant, engine thrust and mixture ratio. The flowrate through the venturi reaches a constant value and becomes independent of outlet pressure when the pressure at throat becomes equal to vapor pressure. In order to develop a numerical model of propulsion system, it is necessary to model cavitating venturies in propellant feed systems. This paper presents a finite volume model of flow network of a cavitating venturi. The venturi was discretized into a number of control volumes and mass, momentum and energy conservation equations in each control volume are simultaneously solved to calculate one-dimensional pressure, density, and flowrate and temperature distribution. The numerical model predicts cavitations at the throat when outlet pressure was gradually reduced. Once cavitation starts, with further reduction of downstream pressure, no change in flowrate is found. The numerical predictions have been compared with test data and empirical equation based on Bernoulli's equation.

  15. Spatial distribution of groundwater recharge and base flow: Assessment of controlling factors

    Directory of Open Access Journals (Sweden)

    Z. Zomlot

    2015-09-01

    New hydrological insights for the region: The average resulting recharge is 235 mm/year and occurs mainly in winter. The overall moderate correlation between base flow estimates and modeled recharge rates indicates that base flow is a reasonable proxy of recharge. Groundwater recharge variation was explained in order of importance by precipitation, soil texture and vegetation cover; while base flow variation was strongly controlled by vegetation cover and groundwater depth. The results of this study highlight the important role of spatial variables in estimation of recharge and base flow. In addition, the prominent role of vegetation makes clear the potential importance of land-use changes on recharge and hence the need to include a proper strategy for land-use change in sustainable management of groundwater resources.

  16. Tracer responses and control of vessels with variable flow and volume

    International Nuclear Information System (INIS)

    Niemi, A.J.

    1990-01-01

    Continuous flow vessels which are subject to variation of flow and volume are characterized by time-variable parameters. It is shown that their residence time distributions and weighting functions obtained by tracer testing are made invariant with regard to the integrated flow variables which are introduced. Under variable flow but constant volume, one such integrated variable is sufficient. Under variable volume, two different variables are suggested for the residence time distribution and weighting function, while the appropriate variable of the perfect mixer differs distinctly from that of vessels with a distinct velocity profile. It is shown through a number of example cases, that an agreement with their mathematical models is reached. The approach is extended to include also arbitrary, non-analytic response functions obtained by tracer measurements. Applications of the derived models and their incorporation in automatic control algorithms is discussed. (orig.) [de

  17. Characteristics of pulsed plasma synthetic jet and its control effect on supersonic flow

    Directory of Open Access Journals (Sweden)

    Di Jin

    2015-02-01

    Full Text Available The plasma synthetic jet is a novel flow control approach which is currently being studied. In this paper its characteristic and control effect on supersonic flow is investigated both experimentally and numerically. In the experiment, the formation of plasma synthetic jet and its propagation velocity in quiescent air are recorded and calculated with time resolved schlieren method. The jet velocity is up to 100 m/s and no remarkable difference has been found after changing discharge parameters. When applied in Mach 2 supersonic flow, an obvious shockwave can be observed. In the modeling of electrical heating, the arc domain is not defined as an initial condition with fixed temperature or pressure, but a source term with time-varying input power density, which is expected to better describe the influence of heating process. Velocity variation with different heating efficiencies is presented and discussed and a peak velocity of 850 m/s is achieved in still air with heating power density of 5.0 × 1012 W/m3. For more details on the interaction between plasma synthetic jet and supersonic flow, the plasma synthetic jet induced shockwave and the disturbances in the boundary layer are numerically researched. All the results have demonstrated the control authority of plasma synthetic jet onto supersonic flow.

  18. Information Flow Analysis for Human-System Interaction in the SG Level Control

    International Nuclear Information System (INIS)

    Kim, Jong Hyun; Shin, Yeong Cheol

    2008-01-01

    Interaction between automatic control and operators is one of main issues in the application of automation technology. Inappropriate information from automatic control systems causes unexpected problems in human-automation collaboration. Poor information becomes critical, especially when the operator takes over the control from an automation system. Operators cannot properly handle the situation transferred from the automatic mode because of inadequate situation awareness, if the operator is out-of-the loop and the automatic control system fails. Some cases of unplanned reactor trips during the transition between the manual mode and the automatic mode are reported in nuclear power plants (NPPs). Among unplanned reactor trips since 2002, two cases were partially caused by automation-related failures of steam generator (SG) level control. This paper conducts information flow analysis to identify information and control requirement for human-system interaction of SG level control. At first, this paper identifies the level of automation in SG level control systems and then function allocation between system control and human operators. Then information flow analysis for monitoring and transition of automation is performed by adapting job process chart. Information and control requirements will be useful as an input for the human-system interface (HSI) design of SG level control

  19. Artificial blood-flow controlling effects of inhomogeneity of twisted magnetic fields

    Science.gov (United States)

    Nakagawa, Hidenori; Ohuchi, Mikio

    2017-06-01

    We developed a blood-flow controlling system using magnetic therapy for some types of nervous diseases. In our research, we utilized overlapped extremely low frequency (ELF) fields for the most effective blood-flow for the system. Results showed the possibility that the inhomogeneous region obtained by overlapping the fields at 50 Hz, namely, a desirably twisted field revealed a significant difference in induced electromotive forces at the insertion points of electrodes. In addition, ELF exposures with a high inhomogeneity of the twisted field at 50 Hz out of phase were more effective in generating an induced electromotive difference by approximately 31%, as contrasted with the difference generated by the exposure in phase. We expect that the increase of the inhomogeneity of the twisted field around a blood vessel can produce the most effective electromotive difference in the blood, and also moderately affect the excitable cells relating to the autonomic nervous system for an outstanding blood-flow control in vivo.

  20. Aerodynamic analysis of potential use of flow control devices on helicopter rotor blades

    International Nuclear Information System (INIS)

    Tejero, F; Doerffer, P; Szulc, O

    2014-01-01

    The interest in the application of flow control devices has been rising in the last years. Recently, several passive streamwise vortex generators have been analysed in a configuration of a curved wall nozzle within the framework of the UFAST project (Unsteady Effects of Shock Wave Induced Separation, 2005 – 2009). Experimental and numerical results proved that the technology is effective in delaying flow separation. The numerical investigation has been extended to helicopter rotor blades in hover and forward flight applying the FLOWer solver (RANS approach) implementing the chimera overlapping grids technique and high performance computing. CFD results for hover conditions confirm that the proposed passive control method reduces the flow separation increasing the thrust over power consumption. The paper presents the numerical validation for both states of flight and the possible implementation of RVGs on helicopter rotor blades.

  1. Representing Causality and Reasoning about Controllability of Multi-level Flow-Systems

    DEFF Research Database (Denmark)

    Heussen, Kai; Lind, Morten

    2010-01-01

    Safe operation of complex processes requires that operators maintain situational-awareness even in highly automated environments. Automatic reasoning can support operators as well as the automation system itself to react effectively and appropriately to disturbances. However, knowledge......-based reasoning about control situations remains a challenge due to the entanglement of process and control systems that co-establish the intended causal structure of a process. Due to this entanglement, reasoning about such systems depends on a coherent representation of control and process. This paper explains...... modeling of controlled processes with multilevelflow models and proposes a new framework for modeling causal influence in multilevel flow models on the basis of a flow/potential analogy. The results are illustrated on examples from the domain of electric power systems....

  2. Traffic flow impacts of adaptive cruise control deactivation and (Re)activation with cooperative driver behavior

    NARCIS (Netherlands)

    Klunder, G.; Li, M.; Minderhoud, M.

    2009-01-01

    In 2006 in the Netherlands, a field operational test was carried out to study the effect of adaptive cruise control (ACC) and lane departure warning on driver behavior and traffic flow in real traffic. To estimate the effect for larger penetration rates, simulations were needed. For a reliable

  3. Experimental investigation of flow-induced control-element movements by noise analysis

    International Nuclear Information System (INIS)

    Grunwald, G.; Liewers, P.; Schumann, P.; Weiss, F.P.

    1978-01-01

    The possibility has been reported of separating a single noise component due to flow-induced vibrations of a certain control element from a complex neutron signal which also contained contributions of many other control elements vibrating similarly. One of the basic assumptions for the different methods applied was that the body sound signal originating from touch events with the channel wall is closely correlated with the control-element movement. Some discrepancies between the results of the different methods showed that this assumption may not be entirely fulfilled. This paper investigates this correlation more accurately by measurements of an air flow model of the control-element channel. The pendulum movement of the element, and the body-sound signal due to the touch events with the channel wall, were measured at different flow-rates. The result is that the correlation is not an ideal one. For a constant flow-rate the touch events happen mainly within a small angle region, which means that the touch event marks a certain phase of the movement period and is therefore correlated with the movement. The dispersion of the touch events' angle distribution explains the small discrepancy between the so-called modified averaging method, which uses the sound signal to trigger the averaging procedure, and the partial spectral density method. But not all discrepancies can be explained by these results; they await further investigation. (author)

  4. Piezoelectric microvalve for precise control of gas flow at high pressure

    NARCIS (Netherlands)

    Fazal, I.; Elwenspoek, Michael Curt

    2008-01-01

    We present a normally open piezoelectric actuated micro valve, based on the novel concept of micro and fine machining technology. This new design allows a wide controllable range for high flow at a high pressure difference between inlet and outlet. This promising combination of micro and fine

  5. Application of cool wan flow control weight scale design on belt conveyor

    International Nuclear Information System (INIS)

    Djokorayono, Rony; Junus; Rivai, A; Gunarwan; Indarzah

    2003-01-01

    Control of the coal mass flow on the belt conveyor at coal handling unit PLTU Suralaya has been designed by using weight scale of gamma absorption technique where accuracy for the measurement of weight scale system is 0,5% to 0,1%. The absorption gamma radiation will be measured by scintillation or ion chamber detector

  6. Applying work flow control in make-to-order job shops

    DEFF Research Database (Denmark)

    Harrod, Steven; Kanet, John J.

    2013-01-01

    of a relatively new work flow control method, "paired overlapping loops of cards" or POLCA. Additionally, this paper explains "lockup," a previously unreported terminal system blocking behavior. A management method to prevent occurrence of lockup is provided. (C) 2012 Elsevier B.V. All rights reserved....

  7. Novel flat datacenter network architecture based on scalable and flow-controlled optical switch system

    NARCIS (Netherlands)

    Miao, W.; Luo, J.; Di Lucente, S.; Dorren, H.J.S.; Calabretta, N.

    2013-01-01

    We propose and demonstrate an optical flat datacenter network based on scalable optical switch system with optical flow control. 4×4 dynamic switch operation at 40 Gb/s reported 300ns minimum end-to-end latency (including 25m transmission link) and

  8. Structural Controls on Groundwater Flow in Basement Terrains: Geophysical, Remote Sensing, and Field Investigations in Sinai

    KAUST Repository

    Mohamed, Lamees; Sultan, Mohamed; Ahmed, Mohamed; Zaki, Abotalib; Sauck, William; Soliman, Farouk; Yan, Eugene; Elkadiri, Racha; Abouelmagd, Abdou

    2015-01-01

    of the structural controls on the groundwater flow. The increase in satellite-based radar backscattering values following a large precipitation event (34 mm on 17–18 January 2010) was used to identify water-bearing features, here interpreted as preferred pathways

  9. A distributed control algorithm for internal flow management in a multi-zone climate unit

    NARCIS (Netherlands)

    Persis, C. De; Jessen, J.J.; Izadi-Zamanabadi, R.; Schiøler, H.

    2008-01-01

    We examine a distributed control problem for internal flow management in a multi-zone climate unit. The problem consists of guaranteeing prescribed indoor climate conditions in a cascade connection of an arbitrarily large number of communicating zones, in which air masses are exchanged to redirect

  10. Butterfly valve with metal seals controls flow of hydrogen from cryogenic through high temperatures

    Science.gov (United States)

    Johnson, L. D.

    1967-01-01

    Butterfly valve with metal seals operates over a temperature range of minus 423 degrees to plus 440 degrees F with hydrogen as a medium and in a radiation environment. Media flow is controlled by an internal butterfly disk which is rotated by an actuation shaft.

  11. Experimental Study of Stable Surfaces for Anti-Slug Control in Multi-phase Flow

    DEFF Research Database (Denmark)

    Pedersen, Simon; Løhndorf, Petar Durdevic; Yang, Zhenyu

    2014-01-01

    -phase flow dynamics, the slug can be avoided or eliminated by proper facility design and control of operational conditions. Based on a testing facility which can emulate a pipeline-riser or a gas-lifted production well in a scaled-down manner, this paper experimentally studies the correlations of key...

  12. Controlling the structure of forced convective flow by means of rotating magnetic-field inductors

    International Nuclear Information System (INIS)

    Sorkin, M.Z.; Mozgirs, O.Kh.

    1993-01-01

    The forced convective flow generated by a rotating magnetic-field inductor is used in a melt as a means of controlling the transfer of mass and heat in the case of directed crystallization. An obvious advantage in using a rotating field is the generation of azimuthal twisting of the fluid, this providing for an evening out of the crystallization conditions in the azimuthal direction under nonsymmetrical boundary conditions in an actual technological process. From the standpoint of affecting the crystallization processes it would be preferable to use an inductor which would allow alteration of the intensity and of the direction of the meridional flow. Mixing in the form of velocity pulsations generated by the inductor within the melt would be if interest from the standpoint of affecting the crystallization processes, in particular to intensify the crystallization purification. The authors propose the use of a double magnetohydrodynmic rotator which consists of two rotating magnetic-field inductors, separated in altitude, with separate power supplies. The supply of power to the inductors with various current loads allows the generation of a controllable nonuniformity in field distribution and in the azimuthal velocity through the altitude and thus allows control of both the intensity and configuration of the meridional flows. The dual rotator makes it possible to purposefully control the structure of the meridional flows and the pulsation component of velocity and can be recommended for use in processes of directed crystallization as well as in crystallization purification. 4 refs., 3 figs

  13. On the flow around Glauert-Goldschmied body in the narrow channel and separation control strategy

    Czech Academy of Sciences Publication Activity Database

    Procházka, Pavel P.; Uruba, Václav

    2016-01-01

    Roč. 16, č. 1 (2016), s. 643-644 ISSN 1617-7061 R&D Projects: GA ČR(CZ) GP14-25354P Institutional support: RVO:61388998 Keywords : PIV * active flow control * Glauert-Goldschmied body Subject RIV: BK - Fluid Dynamics http://onlinelibrary.wiley.com/doi/10.1002/pamm.201610310/full

  14. Direct microcomputer controlled determination of zinc in human serum by flow injection atomic absorption spectrometry

    DEFF Research Database (Denmark)

    Simonsen, Kirsten Wiese; Nielsen, Bent; Jensen, Arne

    1986-01-01

    A procedure is described for the direct determination of zinc in human serum by fully automated, microcomputer controlled flow injection atomic absorption spectrometry (Fl-AAS). The Fl system is pumpless, using the negative pressure created by the nebuliser. It only consists of a three-way valve......, programmable from the microcomputer, to control the sample volume. No pre-treatment of the samples is necessary. The limit of detection is 0.14 mg l–1, and only small amounts of serum (

  15. An approximate analysis of the diffusing flow in a self-controlled heat pipe.

    Science.gov (United States)

    Somogyi, D.; Yen, H. H.

    1973-01-01

    Constant-density two-dimensional axisymmetric equations are presented for the diffusing flow of a class of self-controlled heat pipes. The analysis is restricted to the vapor space. Condensation of the vapor is related to its mass fraction at the wall by the gas kinetic formula. The Karman-Pohlhausen integral method is applied to obtain approximate solutions. Solutions are presented for a water heat pipe with neon control gas.

  16. Quality control in the application of flow cytometric assays of genetic damage due to environmental contaminants

    International Nuclear Information System (INIS)

    McCreedy, C.D.; Jagoe, C.H.; Brisbin, I.L. Jr.; Wentworth, R.W.; Dallas, C.E.

    1995-01-01

    Clinical technologies, such as flow cytometry, are increasingly adopted by environmental toxicologists to identify resource damage associated with exposure to xenobiotics. One application of flow cytometry allows the rapid determination of the DNA content of large numbers of individual cells, and can be used to detect aneuploidy or other genetic abnormalities. The laboratory has used this methodology in studies of genetic toxicology of fish, birds, arid mammals exposed to organic pollutants, metals and radionuclides, However, without appropriate quality controls, false positive results and other artifacts can arise from sample handling and preparations, inter and intra-individual variations, instrument noise and other sources. The authors describe the routine measures this laboratory employs to maintain quality control of genomic DNA analysis, including the control of staining conditions, machine standardization, pulse-width doublet discrimination, and, in particular, the use of internal controls and the use of time as a cytometric parameter. Neglect of these controls can produce erroneous results, leading to conclusions of genetic abnormalities when none are present. Conversely, attention to these controls, routinely used in clinical settings, facilitates the interpretation of flow cytometric data and allows the application of this sensitive indicator of genotoxic effects to a variety of environmental problems

  17. Active flow control on a NACA 23012 airfoil model by means of magnetohydrodynamic plasma actuator

    International Nuclear Information System (INIS)

    Kazanskiy, P N; Moralev, I A; Bityurin, V A; Efimov, A V

    2016-01-01

    The paper is devoted to the study of high speed flow control around the airfoil by means of the Lorentz force. The latter is formed by creating the pulsed arc filament, moving in the magnetic field along the upper airfoil surface. The research was performed for the NACA23012 airfoil model at flow velocities up to 60 m/s (134 mph). The dynamic measurement of the aerodynamic forces on the airfoil was made. Changes up to 5% in an average value of lift and pitching moment were obtained at pulse repetition frequency up to 13 Hz and average discharge power less than 200 W. The amplitude of lift force oscillation was obtained as high as 10%, with the integration time of the balance 30 ms. The dynamic flow visualization of an airfoil model after a single discharge ignition was performed. It is shown that interaction of the main flow with the arc-induced disturbance leads to the dramatic changes in the flow structure. It was shown that the upstream movement of the arc channel (I = 40-700 A) leads to the local flow separation and simultaneously to the formation of a high pressure region above the model surface. Current paper presents investigation of previous work. (paper)

  18. Controls on groundwater flow in the Bengal Basin of India and Bangladesh: regional modeling analysis

    Science.gov (United States)

    Michael, Holly A.; Voss, Clifford I.

    2009-11-01

    Groundwater for domestic and irrigation purposes is produced primarily from shallow parts of the Bengal Basin aquifer system (India and Bangladesh), which contains high concentrations of dissolved arsenic (exceeding worldwide drinking water standards), though deeper groundwater is generally low in arsenic. An essential first step for determining sustainable management of the deep groundwater resource is identification of hydrogeologic controls on flow and quantification of basin-scale groundwater flow patterns. Results from groundwater modeling, in which the Bengal Basin aquifer system is represented as a single aquifer with higher horizontal than vertical hydraulic conductivity, indicate that this anisotropy is the primary hydrogeologic control on the natural flowpath lengths. Despite extremely low hydraulic gradients due to minimal topographic relief, anisotropy implies large-scale (tens to hundreds of kilometers) flow at depth. Other hydrogeologic factors, including lateral and vertical changes in hydraulic conductivity, have minor effects on overall flow patterns. However, because natural hydraulic gradients are low, the impact of pumping on groundwater flow is overwhelming; modeling indicates that pumping has substantially changed the shallow groundwater budget and flowpaths from predevelopment conditions.

  19. Control of unsteady separated flow associated with the dynamic pitching of airfoils

    Science.gov (United States)

    Ahmed, Sajeer

    1991-01-01

    Although studies have been done to understand the dependence of parameters for the occurrence of deep stall, studies to control the flow for sustaining lift for a longer time has been little. To sustain the lift for a longer time, an understanding of the development of the flow over the airfoil is essential. Studies at high speed are required to study how the flow behavior is dictated by the effects of compressibility. When the airfoil is pitched up in ramp motion or during the upstroke of an oscillatory cycle, the flow development on the upper surface of the airfoil and the formation of the vortex dictates the increase in lift behavior. Vortex shedding past the training edge decreases the lift. It is not clear what is the mechanism associated with the unsteady separation and vortex formation in present unsteady environment. To develop any flow control device, to suppress the vortex formation or delay separation, it is important that this mechanism be properly understood. The research activities directed toward understanding these questions are presented and the results are summarized.

  20. Environmental controls on sap flow in black locust forest in Loess Plateau, China.

    Science.gov (United States)

    Ma, Changkun; Luo, Yi; Shao, Mingan; Li, Xiangdong; Sun, Lin; Jia, Xiaoxu

    2017-10-13

    Black locust accounts for over 90% of artificial forests in China's Loess Plateau region. However, water use of black locust is an uphill challenge for this semi-arid region. To accurately quantify tree water use and to explain the related hydrological processes, it is important to collect reliable data for application in the estimation of sap flow and its response to environmental factors. This study measured sap flow in black locust in the 2015 and 2016 growth seasons using the thermal dissipation probes technique and laboratory-calibrated Granier's equation. The study showed that the laboratory calibrated coefficient α was much larger than the original value presented by Granier, while the coefficient β was similar to the original one. The average daily transpiration was 2.1 mm day -1 for 2015 and 1.6 mm day -1 for 2016. Net solar radiation (Rn) was the key meteorological factor controlling sap flow, followed by vapor pressure deficit (VPD) and then temperature (T). VPD had a threshold control on sap flow at threshold values of 1.9 kPa for 2015 and 1.6 kPa for 2016. The effects of diurnal hysteresis of Rn, VPD and T on sap flow were evident, indicating that black locust water use was conservative.

  1. A model for investigating the control of muscle blood flow: the masseteric artery in conscious rabbits

    International Nuclear Information System (INIS)

    Roatta, S; Mohammed, M; Turturici, M; Milano, L; Passatore, M

    2010-01-01

    The complex interplay of neural, metabolic, myogenic and mechanical mechanisms that regulate blood flow in skeletal muscle (MBF) is still incompletely understood. For the first time, a method is presented for high time-resolution recording of MBF from a purely muscular artery in physiological conditions. Ultrasound perivascular flow probes were implanted (n = 15) mono- or bilaterally around the masseteric branch of the facial artery in nine rabbits and tested up to 16 days after implant. Reliable and stable recordings were achieved in 50% of implants. Blood flow was observed to increase from a resting level of 0.2–0.3 ml min −1 up to 4.0–6.0 ml min −1 during spontaneous masticatory activity. In addition, within single masticatory cycles marked back flow transients could be observed (peak flow = −10 ml min −1 ) during powerful masticatory strokes but not during mild mastication. The possibility of (1) surgically removing the sympathetic supply to the relevant vascular bed and of (2) bilaterally monitoring the perfusion of masseter muscles thus allowing to use one side as control side for different types of interventions makes this model a useful tool for disentangling the different mechanisms involved in the control of MBF. (note)

  2. Effect of automatic recirculation flow control on the transient response for Lungmen ABWR plant

    Energy Technology Data Exchange (ETDEWEB)

    Tzang, Y.-C., E-mail: yctzang@aec.gov.t [National Tsing Hua University, Department of Engineering and System Science, Hsinchu 30013, Taiwan (China); Chiang, R.-F.; Ferng, Y.-M.; Pei, B.-S. [National Tsing Hua University, Department of Engineering and System Science, Hsinchu 30013, Taiwan (China)

    2009-12-15

    In this study the automatic mode of the recirculation flow control system (RFCS) for the Lungmen ABWR plant has been modeled and incorporated into the basic RETRAN-02 system model. The integrated system model is then used to perform the analyses for the two transients in which the automatic RFCS is involved. The two transients selected are: (1) one reactor internal pump (RIP) trip, and (2) loss of feedwater heating. In general, the integrated system model can predict well the response of key system parameters, including neutron flux, steam dome pressure, heat flux, RIP flow, core inlet flow, feedwater flow, steam flow, and reactor water level. The transients are also analyzed for manual RFCS case, between the automatic RFCS and the manual RFCS cases, comparisons of the transient response for the key system parameter show that the difference of transient response can be clearly identified. Also, the results show that the DELTACPR (delta critical power ratio) for the transients analyzed may not be less limiting for the automatic RFCS case under certain combination of control system settings.

  3. Controls on groundwater flow in the Bengal Basin of India and Bangladesh: Regional modeling analysis

    Science.gov (United States)

    Michael, H.A.; Voss, C.I.

    2009-01-01

    Groundwater for domestic and irrigation purposes is produced primarily from shallow parts of the Bengal Basin aquifer system (India and Bangladesh), which contains high concentrations of dissolved arsenic (exceeding worldwide drinking water standards), though deeper groundwater is generally low in arsenic. An essential first step for determining sustainable management of the deep groundwater resource is identification of hydrogeologic controls on flow and quantification of basin-scale groundwater flow patterns. Results from groundwater modeling, in which the Bengal Basin aquifer system is represented as a single aquifer with higher horizontal than vertical hydraulic conductivity, indicate that this anisotropy is the primary hydrogeologic control on the natural flowpath lengths. Despite extremely low hydraulic gradients due to minimal topographic relief, anisotropy implies large-scale (tens to hundreds of kilometers) flow at depth. Other hydrogeologic factors, including lateral and vertical changes in hydraulic conductivity, have minor effects on overall flow patterns. However, because natural hydraulic gradients are low, the impact of pumping on groundwater flow is overwhelming; modeling indicates that pumping has substantially changed the shallow groundwater budget and flowpaths from predevelopment conditions. ?? Springer-Verlag 2009.

  4. Higher energy efficiency and better water quality by using model predictive flow control at water supply systems

    NARCIS (Netherlands)

    Bakker, M.; Verberk, J.Q.J.C.; Palmen, L.J.; Sperber, V.; Bakker, G.

    2011-01-01

    Half of all water supply systems in the Netherlands are controlled by model predictive flow control; the other half are controlled by conventional level based control. The differences between conventional level based control and model predictive control were investigated in experiments at five full

  5. The control variable method: a fully implicit numerical method for solving conservation equations for unsteady multidimensional fluid flow

    International Nuclear Information System (INIS)

    Le Coq, G.; Boudsocq, G.; Raymond, P.

    1983-03-01

    The Control Variable Method is extended to multidimensional fluid flow transient computations. In this paper basic principles of the method are given. The method uses a fully implicit space discretization and is based on the decomposition of the momentum flux tensor into scalar, vectorial, and tensorial, terms. Finally some computations about viscous-driven flow and buoyancy-driven flow in cavity are presented

  6. Transient flow analysis of the single cylinder for the control rod hydraulic driving system

    International Nuclear Information System (INIS)

    Sun, Xinming; Qin, Benke; Bo, Hanliang

    2017-01-01

    Highlights: • The control rod hydraulic driving system(CRHDS) is a new type of built-in control rod drive technology. The hydraulic cylinder is the main component of the CRHDS. • Transient flow phenomenon in the CRHDS is studied by experiments under different working conditions. • The working mechanism of the hydraulic cylinder step motion and the key characteristic parameters are analyzed based on the experimental results. - Abstract: The control rod hydraulic driving system (CRHDS) is a new type of built-in control rod drive technology. In the CRHDS the pulse flow from the pump into the hydraulic cylinder of the control rod hydraulic drive mechanism (CRHDM) is regulated by the integrated valve to perform the step motion of the reactor control rod. Transient flow occurs in the CRHDS during control rod step motion process which is studied by experiments. The time-history curves of flow rate, pressure and inner cylinder displacement were analyzed, and the results show that the water hammer pressure peak during the step-up motion is high, while there are no obvious pressure fluctuations in the corresponding step-down motion. In the step-up process, the pressure fluctuation amplitude increases with the increase of CRHDS driving pressure. The step-up time and the pressure increasing time before step-up decreases with the driving pressure. The step-up pressure increases with the driving pressure. In the step-down process, the step-down time, the step-down pressure and the pressure decreasing time before step-down do not change with the increase of the driving pressure. The experimental results lay the base for the working principle and vibration reduction analysis of the CRHDS and it’s also helpful for improvement of the working performance of the key facilities and instruments of the CRHDS loop.

  7. Internal hydraulic control in the Little Belt, Denmark - observations of flow configurations and water mass formation

    Science.gov (United States)

    Holtegaard Nielsen, Morten; Vang, Torben; Chresten Lund-Hansen, Lars

    2017-12-01

    Internal hydraulic control, which occurs when stratified water masses are forced through an abrupt constriction, plays an enormous role in nature on both large and regional scales with respect to dynamics, circulation, and water mass formation. Despite a growing literature on this subject surprisingly few direct observations have been made that conclusively show the existence of and the circumstances related to internal hydraulic control in nature. In this study we present observations from the Little Belt, Denmark, one of three narrow straits connecting the Baltic Sea and the North Sea. The observations (comprised primarily of along-strait, detailed transects of salinity and temperature; continuous observations of flow velocity, salinity, and temperature at a permanent station; and numerous vertical profiles of salinity, temperature, fluorescence, and flow velocity in various locations) show that internal hydraulic control is a frequently occurring phenomenon in the Little Belt. The observations, which are limited to south-going flows of approximately two-layered water masses, show that internal hydraulic control may take either of two configurations, i.e. the lower or the upper layer being the active, accelerating one. This is connected to the depth of the pycnocline on the upstream side and the topography, which is both deepening and contracting toward the narrow part of the Little Belt. The existence of two possible flow configurations is known from theoretical and laboratory studies, but we believe that this has never been observed in nature and reported before. The water masses formed by the intense mixing, which is tightly connected with the presence of control, may be found far downstream of the point of control. The observations show that these particular water masses are associated with chlorophyll concentrations that are considerably higher than in adjacent water masses, showing that control has a considerable influence on the primary production and

  8. Active Control of Flow around NACA 0015 Airfoil by Using DBD Plasma Actuator

    Directory of Open Access Journals (Sweden)

    Şanlısoy A.

    2013-04-01

    Full Text Available In this study, effect of plasma actuator on a flat plate and manipulation of flow separation on NACA0015 airfoil with plasma actuator at low Reynolds numbers were experimentally investigated. In the first section of the study, plasma actuator which consists of positive and grounded electrode couple and dielectric layer, located on a flat plate was actuated at different frequencies and peak to peak voltages in range of 3-5 kHz and 6-12 kV respectively. Theinduced air flow velocity on the surface of flat plate was measured by pitot tube at different locations behind the actuator. The influence of dielectricthickness and unsteady actuation with duty cycle was also examined. In the second section, the effect of plasma actuator on NACA0015 airfoil was studied atReynolds number 15000 and 30000. Four plasma actuators were placed at x/C = 0.1, 0.3, 0.5 and 0.9, and different electrode combinations were activated by sinusoidal signal. Flow visualizations were done when the attack angles were 0°, 5°, 10°, 15° and 20°. The results indicate that up to the 15° attack angle, the separated flow was reattached by plasma actuator at 12kV peak to peak voltage and 4 kHz frequency. However, 12 kVpp voltage was insufficient to reattach the flow at 20° angle of attack. The separated flow could be reattached by increasing the voltage up to 13 kV. Lift coefficient was also increased by the manipulated flow over the airfoil. Results showed that even high attack angles, the actuators can control the flow separation and prevent the airfoil from stall at low Reynolds numbers.

  9. Controls on Lava Flow Morphology and Propagation: Using Laboratory Analogue Experiments

    Science.gov (United States)

    Peters, S.; Clarke, A. B.

    2017-12-01

    The morphology of lava flows is controlled by eruption rate, composition, cooling rate, and topography [Fink and Griffiths, 1990; Gregg and Fink, 2000, 2006]. Lava flows are used to understand how volcanoes, volcanic fields, and igneous provinces formed and evolved [Gregg and Fink., 1996; Sheth, 2006]. This is particularly important for other planets where compositional data is limited and historical context is nonexistent. Numerical modeling of lava flows remains challenging, but has been aided by laboratory analog experiments [Gregg and Keszrthelyi, 2004; Soule and Cashman, 2004]. Experiments using polyethylene glycol (PEG) 600 wax have been performed to understand lava flow emplacement [Fink and Griffiths, 1990, 1992; Gregg and Fink, 2000]. These experiments established psi (hereafter denoted by Ψ), a dimensionless parameter that relates crust formation and advection timescales of a viscous gravity current. Four primary flow morphologies corresponding to discreet Ψ ranges were observed. Gregg and Fink [2000] also investigated flows on slopes and found that steeper slopes increase the effective effusion rate producing predicted morphologies at lower Ψ values. Additional work is needed to constrain the Ψ parameter space, evaluate the predictive capability of Ψ, and determine if the preserved flow morphology can be used to indicate the initial flow conditions. We performed 514 experiments to address the following controls on lava flow morphology: slope (n = 282), unsteadiness/pulsations (n = 58), slope & unsteadiness/pulsations (n = 174), distal processes, and emplacement vs. post-emplacement morphologies. Our slope experiments reveal a similar trend to Gregg and Fink [2000] with the caveat that very high and very low local & source eruption rates can reduce the apparent predictive capability of Ψ. Predicted Ψ morphologies were often produced halfway through the eruption. Our pulse experiments are expected to produce morphologies unique to each eruption rate

  10. History of Suction-Type Laminar-Flow Control with Emphasis on Flight Resrearch: Monographs in Aerospace History Number 13

    Science.gov (United States)

    Braslow, A. L.

    1999-01-01

    The paper contains the following sections: Foreword; Preface; Laminar-Flow Control Concepts and Scope of Monograph; Early Research on Suction-Type Laminar-Flow Control (Research from the 1930s through the War Years; Research from after World War II to the Mid-1960s); Post X-21 Research on Suction-Type Laminar-Flow Control; Status of Laminar-Flow Control Technology in the Mid-1990s; Glossary; Document 1-Aeronautics Panel, AACB, R&D Review, Report of the Subpanel on Aeronautic Energy Conservation/Fuels; Document 2-Report of Review Group on X-21A Laminar Flow Control Program; Document 3-Langley Research Center Announcement, Establishment of Laminar Flow Control Working Group; Document 4-Intercenter Agreement for Laminar Flow Control Leading Edge Glove Flights, LaRC and DFRC; Document 5-Flight Report NLF-144, of AFTIF-111 Aircraft with the TACT Wing Modified by a Natural Laminar Flow Glove; Document 6-Flight Record, F-16XL Supersonic Laminar Flow Control Aircraft; Index; and About the Author.

  11. Development and Application of Plasma Actuators for Active Control of High-Speed and High Reynolds Number Flows

    Science.gov (United States)

    Sammy, Mo

    2010-01-01

    Active flow control is often used to manipulate flow instabilities to achieve a desired goal (e.g. prevent separation, enhance mixing, reduce noise, etc.). Instability frequencies normally scale with flow velocity scale and inversely with flow length scale (U/l). In a laboratory setting for such flow experiments, U is high, but l is low, resulting in high instability frequency. In addition, high momentum and high background noise & turbulence in the flow necessitate high amplitude actuation. Developing a high amplitude and high frequency actuator is a major challenge. Ironically, these requirements ease up in application (but other issues arise).

  12. Analysis and distributed control of power flow in DC microgrids to improve system efficiency

    DEFF Research Database (Denmark)

    Chen, Fang; Burgos, Rolando; Boroyevich, Dushan

    2016-01-01

    DC Microgrid attains popularity in integrating renewable energy sources and batteries. It also has the potential to achieve higher efficiency than ac power grid under the condition of optimized power flow. In this paper, a general dc microgrid is modeled based on a cluster of general dc nodes......, which includes constant power renewables generation, droop-controlled voltage source and different kinds of load. Then the dc power flow is solved for optimization. A voltage restoration method based on consensus communication is used to restore the voltage deviation from droop characteristic...

  13. Gravity insensitive inventory control device for a two-phase flow system

    International Nuclear Information System (INIS)

    Bland, T.J.

    1987-01-01

    A liquid inventory control device is described for a flow system where the liquid changes phase to a vapor and back and a pitot pump separates vapor from liquid and pumps the liquid to a component of the flow system comprising: a liquid storage device for storing liquid under pressure, a tube positioned within the pitot pump and in open communication with the liquid storage device, and the tube having an opening positioned within the pitot pump at a location to establish a desired liquid level in the pitot pump and at which level the pressure at the pitot tube inlet will equal the liquid pressure at the liquid storage device

  14. Plasma actuators for active flow control based on a glow discharge

    International Nuclear Information System (INIS)

    Kühn, M.; Kühn-Kauffeldt, M.; Schein, J.; Belinger, A.

    2017-01-01

    In this work a glow discharge based active flow control for high flow velocities and low Reynolds numbers is presented. Unlike common plasma actuators such as dielectric barrier discharge (DBD) or spark jets, this actuator uses small impulse bits at frequencies. The actuator is optimized for frequencies up to 40 kHz to counter Tollmien Schlichting wave effects and so reduce overall air foil drag. Several measurements to prove the non-eroding effect of the actuator and the electrical properties were performed. It was found that the actuator is capable of operating at high frequencies without measurable erosion. (paper)

  15. Modeling and Optimization of Collaborative Passenger Control in Urban Rail Stations under Mass Passenger Flow

    Directory of Open Access Journals (Sweden)

    Lili Wang

    2015-01-01

    Full Text Available With the rapid development of urban rail transit, the phenomenon of outburst passenger flows flocking to stations is occurring much more frequently. Passenger flow control is one of the main methods used to ensure passengers’ safety. While most previous studies have only focused on control measures inside the target station, ignoring the collaboration between stops, this paper puts emphasis on joint passenger control methods during the occurrence of large passenger flows. To provide a theoretic description for the problem under consideration, an integer programming model is built, based on the analysis of passenger delay and the processes by which passengers alight and board. Taking average passenger delay as the objective, the proposed model aims to disperse the pressure of oversaturated stations into others, achieving the optimal state for the entire line. The model is verified using a case study and the results show that restricted access measures taken collaboratively by stations produce less delay and faster evacuation. Finally, a sensitivity analysis is conducted, from which we find that the departure interval and maximum conveying capacity of the train affect passenger delay markedly in the process of passenger control and infer that control measures should be taken at stations near to the one experiencing an emergency.

  16. Power flow control based solely on slow feedback loop for heart pump applications.

    Science.gov (United States)

    Wang, Bob; Hu, Aiguo Patrick; Budgett, David

    2012-06-01

    This paper proposes a new control method for regulating power flow via transcutaneous energy transfer (TET) for implantable heart pumps. Previous work on power flow controller requires a fast feedback loop that needs additional switching devices and resonant capacitors to be added to the primary converter. The proposed power flow controller eliminates these additional components, and it relies solely on a slow feedback loop to directly drive the primary converter to meet the heart pump power demand and ensure zero voltage switching. A controlled change in switching frequency varies the resonant tank shorting period of a current-fed push-pull resonant converter, thus changing the magnitude of the primary resonant voltage, as well as the tuning between primary and secondary resonant tanks. The proposed controller has been implemented successfully using an analogue circuit and has reached an end-to-end power efficiency of 79.6% at 10 W with a switching frequency regulation range of 149.3 kHz to 182.2 kHz.

  17. End-to-End Flow Control for Visual-Haptic Communication under Bandwidth Change

    Science.gov (United States)

    Yashiro, Daisuke; Tian, Dapeng; Yakoh, Takahiro

    This paper proposes an end-to-end flow controller for visual-haptic communication. A visual-haptic communication system transmits non-real-time packets, which contain large-size visual data, and real-time packets, which contain small-size haptic data. When the transmission rate of visual data exceeds the communication bandwidth, the visual-haptic communication system becomes unstable owing to buffer overflow. To solve this problem, an end-to-end flow controller is proposed. This controller determines the optimal transmission rate of visual data on the basis of the traffic conditions, which are estimated by the packets for haptic communication. Experimental results confirm that in the proposed method, a short packet-sending interval and a short delay are achieved under bandwidth change, and thus, high-precision visual-haptic communication is realized.

  18. Flow chemistry to control the synthesis of nano and microparticles for biomedical applications.

    Science.gov (United States)

    Hassan, Natalia; Oyarzun-Ampuero, Felipe; Lara, Pablo; Guerrero, Simón; Cabuil, Valérie; Abou-Hassan, Ali; Kogan, Marcelo J

    2014-03-01

    In this article we review the flow chemistry methodologies for the controlled synthesis of different kind of nano and microparticles for biomedical applications. Injection mechanism has emerged as new alternative for the synthesis of nanoparticles due to this strategy allows achieving superior levels of control of self-assemblies, leading to higher-ordered structures and rapid chemical reactions. Self-assembly events are strongly dependent on factors such as the local concentration of reagents, the mixing rates, and the shear forces, which can be finely tuned, as an example, in a microfluidic device. Injection methods have also proved to be optimal to elaborate microsystems comprising polymer solutions. Concretely, extrusion based methods can provide controlled fluid transport, rapid chemical reactions, and cost-saving advantages over conventional reactors. We provide an update of synthesis of nano and microparticles such as core/shell, Janus, nanocrystals, liposomes, and biopolymeric microgels through flow chemistry, its potential bioapplications and future challenges in this field are discussed.

  19. Accelerated dissolution testing for controlled release microspheres using the flow-through dissolution apparatus.

    Science.gov (United States)

    Collier, Jarrod W; Thakare, Mohan; Garner, Solomon T; Israel, Bridg'ette; Ahmed, Hisham; Granade, Saundra; Strong, Deborah L; Price, James C; Capomacchia, A C

    2009-01-01

    Theophylline controlled release capsules (THEO-24 CR) were used as a model system to evaluate accelerated dissolution tests for process and quality control and formulation development of controlled release formulations. Dissolution test acceleration was provided by increasing temperature, pH, flow rate, or adding surfactant. Electron microscope studies on the theophylline microspheres subsequent to each experiment showed that at pH values of 6.6 and 7.6 the microspheres remained intact, but at pH 8.6 they showed deterioration. As temperature was increased from 37-57 degrees C, no change in microsphere integrity was noted. Increased flow rate also showed no detrimental effect on integrity. The effect of increased temperature was determined to be the statistically significant variable.

  20. Integration of power flow controlling devices and HVDC-systems into the optimal power flow; Integration von leistungsflusssteuernden Komponenten und HGUe-Systemen in die Leistungsflussoptimierung

    Energy Technology Data Exchange (ETDEWEB)

    Natemeyer, Hendrik; Scheufen, Martin; Roehder, Andreas; Schnettler, Armin [RWTH Aachen Univ. (Germany). Inst. fuer Hochspannungstechnik (IFHT)

    2012-07-01

    An integration of High Voltage Direct Current Transmission Systems (HVDC) or Flexible AC Transmission Systems (FACTS) into power systems enables the possibility to actively influence and control the corresponding power flows in the electrical network. The systemic benefits are a more efficient utilization of existing transmission capacities and improved controllability in fault situations. This paper introduces methods of a coordinative control of such devices and their representation in stationary power flow calculations including the control in (n-1)-cases. This might be a useful tool for the network operation, especially in face of more frequently occurring fast system changes. Examples of a corresponding implementation and application are provided. (orig.)

  1. Control of supersonic axisymmetric base flows using passive splitter plates and pulsed plasma actuators

    Science.gov (United States)

    Reedy, Todd Mitchell

    An experimental investigation evaluating the effects of flow control on the near-wake downstream of a blunt-based axisymmetric body in supersonic flow has been conducted. To better understand and control the physical phenomena that govern these massively separated high-speed flows, this research examined both passive and active flow-control methodologies designed to alter the stability characteristics and structure of the near-wake. The passive control investigation consisted of inserting splitter plates into the recirculation region. The active control technique utilized energy deposition from multiple electric-arc plasma discharges placed around the base. The flow-control authority of both methodologies was evaluated with experimental diagnostics including particle image velocimetry, schlieren photography, surface flow visualization, pressure-sensitive paint, and discrete surface pressure measurements. Using a blowdown-type wind tunnel reconstructed specifically for these studies, baseline axisymmetric experiments without control were conducted for a nominal approach Mach number of 2.5. In addition to traditional base pressure measurements, mean velocity and turbulence quantities were acquired using two-component, planar particle image velocimetry. As a result, substantial insight was gained regarding the time-averaged and instantaneous near-wake flow fields. This dataset will supplement the previous benchmark point-wise laser Doppler velocimetry data of Herrin and Dutton (1994) for comparison with new computational predictive techniques. Next, experiments were conducted to study the effects of passive triangular splitter plates placed in the recirculation region behind a blunt-based axisymmetric body. By dividing the near-wake into 1/2, 1/3, and 1/4 cylindrical regions, the time-averaged base pressure distribution, time-series pressure fluctuations, and presumably the stability characteristics were altered. While the spatial base pressure distribution was

  2. A simple mechanism for controlling vortex breakdown in a closed flow

    OpenAIRE

    Cabeza, C.; Sarasua, Gustavo; Marti, Arturo C.; Bove, Italo

    2005-01-01

    This work is focused to study the development and control of the laminar vortex breakdown of a flow enclosed in a cylinder. We show that vortex breakdown can be controlled by the introduction of a small fixed rod in the axis of the cylinder. Our method to control the onset of vortex breakdown is simpler than those previously proposed, since it does not require any auxiliary device system. The effect of the fixed rods may be understood using a simple model based on the failure of the quasi-cyl...

  3. Skin-friction drag reduction in turbulent channel flow based on streamwise shear control

    International Nuclear Information System (INIS)

    Kim, Jung Hoon; Lee, Jae Hwa

    2017-01-01

    Highlights: • We perform DNSs of fully developed turbulent channel flows to explore an active flow control concept using streamwise velocity shear control at the wall. • The structural spacing and wall amplitude parameters are systematically changed to achieve a high-efficient drag reduction rate for longitudinal control surface. • Significant drag reduction is observed with an increase in the two parameters with an accompanying reduction of the Reynolds stresses and vorticity fluctuations. • The generation and evolution of the turbulent vortices in the absence of velocity shear and how they contribute to DR have been examined. - Abstract: It is known that stretching and intensification of a hairpin vortex by mean shear play an important role to create a hairpin vortex packet, which generates the large Reynolds shear stress associated with skin-friction drag in wall-bounded turbulent flows. In order to suppress the mean shear at the wall for high efficient drag reduction (DR), in the present study, we explore an active flow control concept using streamwise shear control (SSC) at the wall. The longitudinal control surface is periodically spanwise-arranged with no-control surface while varying the structural spacing, and an amplitude parameter for imposing the strength of the actuating streamwise velocity at the wall is introduced to further enhance the skin-friction DR. Significant DR is observed with an increase in the two parameters with an accompanying reduction of the Reynolds stresses and vorticity fluctuations, although a further increase in the parameters amplifies the turbulence activity in the near-wall region. In order to study the direct relationship between turbulent vortical structures and DR under the SSC, temporal evolution with initial eddies extracted by conditional averages for Reynolds-stress-maximizing Q2 events are examined. It is shown that the generation of new vortices is dramatically inhibited with an increase in the parameters

  4. Adaptive fuzzy PID control of hydraulic servo control system for large axial flow compressor

    Science.gov (United States)

    Wang, Yannian; Wu, Peizhi; Liu, Chengtao

    2017-09-01

    To improve the stability of the large axial compressor, an efficient and special intelligent hydraulic servo control system is designed and implemented. The adaptive fuzzy PID control algorithm is used to control the position of the hydraulic servo cylinder steadily, which overcomes the drawback that the PID parameters should be adjusted based on the different applications. The simulation and the test results show that the system has a better dynamic property and a stable state performance.

  5. Delay-feedback control strategy for reducing CO2 emission of traffic flow system

    Science.gov (United States)

    Zhang, Li-Dong; Zhu, Wen-Xing

    2015-06-01

    To study the signal control strategy for reducing traffic emission theoretically, we first presented a kind of discrete traffic flow model with relative speed term based on traditional coupled map car-following model. In the model, the relative speed difference between two successive running cars is incorporated into following vehicle's acceleration running equation. Then we analyzed its stability condition with discrete control system stability theory. Third, we designed a delay-feedback controller to suppress traffic jam and decrease traffic emission based on modern controller theory. Last, numerical simulations are made to support our theoretical results, including the comparison of models' stability analysis, the influence of model type and signal control on CO2 emissions. The results show that the temporal behavior of our model is superior to other models, and the traffic signal controller has good effect on traffic jam suppression and traffic CO2 emission, which fully supports the theoretical conclusions.

  6. Securing a robust electrical discharge drilling process by means of flow rate control

    Science.gov (United States)

    Risto, Matthias; Munz, Markus; Haas, Ruediger; Abdolahi, Ali

    2017-10-01

    This paper deals with the increase of the process robustness while drilling cemented carbide using electrical discharge machining (EDM). A demand for high efficiency in the resulting diameter is equivalent with a high robustness of the EDM drilling process. Analysis were done to investigate the process robustness (standard deviation of the borehole diameter) when drilling cemented carbide. The investigation has shown that the dielectric flow rate changes over the drilling process. In this case the flow rate decreased with a shorter tool electrode due to an uneven wear of the tool electrode's cross section. Using a controlled flow rate during the drilling process has led to a reduced standard deviation of the borehole diameter, thus to a higher process robustness when drilling cemented carbide.

  7. Application of laminar flow control to high-bypass-ratio turbofan engine nacelles

    Science.gov (United States)

    Wie, Y. S.; Collier, F. S., Jr.; Wagner, R. D.

    1991-01-01

    Recently, the concept of the application of hybrid laminar flow to modern commercial transport aircraft was successfully flight tested on a Boeing 757 aircraft. In this limited demonstration, in which only part of the upper surface of the swept wing was designed for the attainment of laminar flow, significant local drag reduction was measured. This paper addresses the potential application of this technology to laminarize the external surface of large, modern turbofan engine nacelles which may comprise as much as 5-10 percent of the total wetted area of future commercial transports. A hybrid-laminar-flow-control (HLFC) pressure distribution is specified and the corresponding nacelle geometry is computed utilizing a predictor/corrector design method. Linear stability calculations are conducted to provide predictions of the extent of the laminar boundary layer. Performance studies are presented to determine potential benefits in terms of reduced fuel consumption.

  8. Passive control of cavitating flow around an axisymmetric projectile by using a trip bar

    Directory of Open Access Journals (Sweden)

    Jian Huang

    2017-07-01

    Full Text Available Quasi-periodical evolutions such as shedding and collapsing of unsteady cloud cavitating flow, induce strong pressure fluctuations, what may deteriorate maneuvering stability and corrode surfaces of underwater vehicles. This paper analyzed effects on cavitation stability of a trip bar arranged on high-speed underwater projectile. Small scale water tank experiment and large eddy simulation using the open source software OpenFOAM were used, and the results agree well with each other. Results also indicate that trip bar can obstruct downstream re-entrant jet and pressure wave propagation caused by collapse, resulting in a relatively stable sheet cavity between trip bar and shoulder of projectiles. Keywords: Unsteady cavitating flow, Trip bar, Re-entrant jet, Passive flow control

  9. Flow Management to Control Excessive Growth of Macrophytes - An Assessment Based on Habitat Suitability Modeling.

    Science.gov (United States)

    Ochs, Konstantin; Rivaes, Rui P; Ferreira, Teresa; Egger, Gregory

    2018-01-01

    Mediterranean rivers in intensive agricultural watersheds usually display outgrowths of macrophytes - notably alien species - due to a combination of high concentrations of nutrients in the water runoff and low flows resulting from water abstraction for irrigation. Standard mechanical and chemical control is used to mitigate the problems associated with excessive growth of plant biomass: mainly less drainage capacity and higher flood risk. However, such control measures are cost and labor-intensive and do not present long-term efficiency. Although the high sensitivity of aquatic vegetation to instream hydraulic conditions is well known, management approaches based on flow management remain relatively unexplored. The aim of our study was therefore to apply physical habitat simulation techniques promoted by the Instream Flow Incremental Method (IFIM) to aquatic macrophytes - the first time it has been applied in this context - in order to model shifts in habitat suitability under different flow scenarios in the Sorraia river in central Portugal. We used this approach to test whether the risk of invasion and channel encroachment by nuisance species can be controlled by setting minimum annual flows. We used 960 randomly distributed survey points to analyze the habitat suitability for the most important aquatic species (including the invasive Brazilian milfoil Myriophyllum aquaticum , Sparganium erectum , and Potamogeton crispus ) in regard to the physical parameters 'flow velocity,' 'water depth,' and 'substrate size'. We chose the lowest discharge period of the year in order to assess the hydraulic conditions while disturbances were at a low-point, thus allowing aquatic vegetation establishment and subsistence. We then used the two-dimensional hydraulic River2D software to model the potential habitat availability for different flow conditions based on the site-specific habitat suitability index for each physical parameter and species. Our results show that the growth

  10. Flow Management to Control Excessive Growth of Macrophytes – An Assessment Based on Habitat Suitability Modeling

    Science.gov (United States)

    Ochs, Konstantin; Rivaes, Rui P.; Ferreira, Teresa; Egger, Gregory

    2018-01-01

    Mediterranean rivers in intensive agricultural watersheds usually display outgrowths of macrophytes – notably alien species – due to a combination of high concentrations of nutrients in the water runoff and low flows resulting from water abstraction for irrigation. Standard mechanical and chemical control is used to mitigate the problems associated with excessive growth of plant biomass: mainly less drainage capacity and higher flood risk. However, such control measures are cost and labor-intensive and do not present long-term efficiency. Although the high sensitivity of aquatic vegetation to instream hydraulic conditions is well known, management approaches based on flow management remain relatively unexplored. The aim of our study was therefore to apply physical habitat simulation techniques promoted by the Instream Flow Incremental Method (IFIM) to aquatic macrophytes – the first time it has been applied in this context – in order to model shifts in habitat suitability under different flow scenarios in the Sorraia river in central Portugal. We used this approach to test whether the risk of invasion and channel encroachment by nuisance species can be controlled by setting minimum annual flows. We used 960 randomly distributed survey points to analyze the habitat suitability for the most important aquatic species (including the invasive Brazilian milfoil Myriophyllum aquaticum, Sparganium erectum, and Potamogeton crispus) in regard to the physical parameters ‘flow velocity,’ ‘water depth,’ and ‘substrate size’. We chose the lowest discharge period of the year in order to assess the hydraulic conditions while disturbances were at a low-point, thus allowing aquatic vegetation establishment and subsistence. We then used the two-dimensional hydraulic River2D software to model the potential habitat availability for different flow conditions based on the site-specific habitat suitability index for each physical parameter and species. Our results show

  11. Leveraging master-slave OpenFlow controller arrangement to improve control plane resiliency in SD-EONs.

    Science.gov (United States)

    Chen, Xiaoliang; Zhao, Bin; Ma, Shoujiang; Chen, Cen; Hu, Daoyun; Zhou, Wenshuang; Zhu, Zuqing

    2015-03-23

    In this paper, we study how to improve the control plane resiliency of software-defined elastic optical networks (SD-EONs) and design a master-slave OpenFlow (OF) controller arrangement. Specifically, we introduce two OF controllers (OF-Cs), i.e., the master and slave OF-Cs, and make them work in a collaborative way to protect the SD-EON against controller failures. We develop a controller communication protocol (CCP) to facilitate the cooperation of the two OF-Cs. With the CCP, the master OF-C (M-OF-C) can synchronize network status to the slave OF-C (S-OF-C) in real time, while S-OF-C can quickly detect the failure of M-OF-C and take over the network control and management (NC&M) tasks timely to avoid service disruption. We implement the proposed framework in an SD-EON control plane testbed built with high-performance servers, and perform NC&M experiments with different network failure scenarios to demonstrate its effectiveness. Experimental results indicate that the proposed system can restore services in both the data and control planes of SD-EON jointly while maintaining relatively good scalability. To the best of our knowledge, this is the first demonstration that realizes control plane resiliency in SD-EONs.

  12. The efficacy of centralized flow rate control in 802.11-based wireless mesh networks

    KAUST Repository

    Jamshaid, K.

    2013-06-13

    Commodity WiFi-based wireless mesh networks (WMNs) can be used to provide last mile Internet access. These networks exhibit extreme unfairness with backlogged traffic sources. Current solutions propose distributed source-rate control algorithms requiring link-layer or transport-layer changes on all mesh nodes. This is often infeasible in large practical deployments. In wireline networks, router-assisted rate control techniques have been proposed for use alongside end-to-end mechanisms. We wish to evaluate the feasibility of establishing similar centralized control via gateways in WMNs. In this paper, we focus on the efficacy of this control rather than the specifics of the controller design mechanism. We answer the question: Given sources that react predictably to congestion notification, can we enforce a desired rate allocation through a single centralized controller? The answer is not obvious because flows experience varying contention levels, and transmissions are scheduled by a node using imperfect local knowledge. We find that common router-assisted flow control schemes used in wired networks fail in WMNs because they assume that (1) links are independent, and (2) router queue buildups are sufficient for detecting congestion. We show that non-work-conserving, rate-based centralized scheduling can effectively enforce rate allocation. It can achieve results comparable to source rate limiting, without requiring any modifications to mesh routers or client devices. 2013 Jamshaid et al.; licensee Springer.

  13. Structural Controls on Groundwater Flow in Basement Terrains: Geophysical, Remote Sensing, and Field Investigations in Sinai

    KAUST Repository

    Mohamed, Lamees

    2015-07-09

    An integrated [very low frequency (VLF) electromagnetic, magnetic, remote sensing, field, and geographic information system (GIS)] study was conducted over the basement complex in southern Sinai (Feiran watershed) for a better understanding of the structural controls on the groundwater flow. The increase in satellite-based radar backscattering values following a large precipitation event (34 mm on 17–18 January 2010) was used to identify water-bearing features, here interpreted as preferred pathways for surface water infiltration. Findings include: (1) spatial analysis in a GIS environment revealed that the distribution of the water-bearing features (conductive features) corresponds to that of fractures, faults, shear zones, dike swarms, and wadi networks; (2) using VLF (43 profiles), magnetic (7 profiles) techniques, and field observations, the majority (85 %) of the investigated conductive features were determined to be preferred pathways for groundwater flow; (3) northwest–southeast- to north–south-trending conductive features that intersect the groundwater flow (southeast to northwest) at low angles capture groundwater flow, whereas northeast–southwest to east–west features that intersect the flow at high angles impound groundwater upstream and could provide potential productive well locations; and (4) similar findings are observed in central Sinai: east–west-trending dextral shear zones (Themed and Sinai Hinge Belt) impede south to north groundwater flow as evidenced by the significant drop in hydraulic head (from 467 to 248 m above mean sea level) across shear zones and by reorientation of regional flow (south–north to southwest–northeast). The adopted integrated methodologies could be readily applied to similar highly fractured basement arid terrains elsewhere. © 2015 Springer Science+Business Media Dordrecht

  14. Controllable Microdroplet Splitting via Additional Lateral Flow and its Application in Rapid Synthesis of Multi-scale Microspheres

    KAUST Repository

    Zhou, Bingpu; Wang, Cong; Xiao, Xiao; Hui, Yu Sanna; Cao, Yulin; Wen, Weijia

    2015-01-01

    In this paper, we demonstrate that controllable microdroplet splitting could be obtained via additional lateral flow with simplicity and high controllability. The volume ratio of the two splitting products can be flexibly regulated by adjusting

  15. Dual turbine power plant and a reheat steam bypass flow control system for use therein

    International Nuclear Information System (INIS)

    Braytenbah, A.S.; Jaegtnes, K.O.

    1977-01-01

    An electric power plant having dual turbine-generators connected to a steam source that includes a high temperature gas cooled nuclear reactor is described. Each turbine comprises a high pressure portion operated by superheat steam and an intermediate-low pressure portion operated by reheat steam; a bypass line is connected across each turbine portion to permit a desired minimum flow of steam from the source at times when the combined flow of steam through the turbine is less than the minimum. Coolant gas is propelled through the reactor by a circulator which is driven by an auxiliary turbine which uses steam exhausted from the high pressure portions and their bypass lines. The pressure of the reheat steam is controlled by a single proportional-plus-integral controller which governs the steam flow through the bypass lines associated with the intermediate-low pressure portions. At times when the controller is not in use its output signal is limited to a value that permits an unbiased response when pressure control is resumed, as in event of a turbine trip. 25 claims, 2 figures

  16. Demonstrating electromagnetic control of free-surface, liquid-metal flows relevant to fusion reactors

    Science.gov (United States)

    Hvasta, M. G.; Kolemen, E.; Fisher, A. E.; Ji, H.

    2018-01-01

    Plasma-facing components (PFC’s) made from solid materials may not be able to withstand the large heat and particle fluxes that will be produced within next-generation fusion reactors. To address the shortcomings of solid PFC’s, a variety of liquid-metal (LM) PFC concepts have been proposed. Many of the suggested LM-PFC designs rely on electromagnetic restraint (Lorentz force) to keep free-surface, liquid-metal flows adhered to the interior surfaces of a fusion reactor. However, there is very little, if any, experimental data demonstrating that free-surface, LM-PFC’s can actually be electromagnetically controlled. Therefore, in this study, electrical currents were injected into a free-surface liquid-metal that was flowing through a uniform magnetic field. The resultant Lorentz force generated within the liquid-metal affected the velocity and depth of the flow in a controllable manner that closely matched theoretical predictions. These results show the promise of electromagnetic control for LM-PFC’s and suggest that electromagnetic control could be further developed to adjust liquid-metal nozzle output, prevent splashing within a tokamak, and alter heat transfer properties for a wide-range of liquid-metal systems.

  17. On-Chip Enucleation of Bovine Oocytes using Microrobot-Assisted Flow-Speed Control

    Directory of Open Access Journals (Sweden)

    Akihiko Ichikawa

    2013-06-01

    Full Text Available In this study, we developed a microfluidic chip with a magnetically driven microrobot for oocyte enucleation. A microfluidic system was specially designed for enucleation, and the microrobot actively controls the local flow-speed distribution in the microfluidic chip. The microrobot can adjust fluid resistances in a channel and can open or close the channel to control the flow distribution. Analytical modeling was conducted to control the fluid speed distribution using the microrobot, and the model was experimentally validated. The novelties of the developed microfluidic system are as follows: (1 the cutting speed improved significantly owing to the local fluid flow control; (2 the cutting volume of the oocyte can be adjusted so that the oocyte undergoes less damage; and (3 the nucleus can be removed properly using the combination of a microrobot and hydrodynamic forces. Using this device, we achieved a minimally invasive enucleation process. The average enucleation time was 2.5 s and the average removal volume ratio was 20%. The proposed new system has the advantages of better operation speed, greater cutting precision, and potential for repeatable enucleation.

  18. Neural control of blood flow during exercise in human metabolic syndrome.

    Science.gov (United States)

    Limberg, Jacqueline K; Morgan, Barbara J; Sebranek, Joshua J; Proctor, Lester T; Eldridge, Marlowe W; Schrage, William G

    2014-09-01

    α-Adrenergic-mediated vasoconstriction is greater during simulated exercise in animal models of metabolic syndrome (MetSyn) when compared with control animals. In an attempt to translate such findings to humans, we hypothesized that adults with MetSyn (n = 14, 35 ± 3 years old) would exhibit greater α-adrenergic responsiveness during exercise when compared with age-matched healthy control subjects (n = 16, 31 ± 3 years old). We measured muscle sympathetic nerve activity (MSNA; microneurography) and forearm blood flow (Doppler ultrasound) during dynamic forearm exercise (15% of maximal voluntary contraction). α-Adrenergic agonists (phenylephrine and clonidine) and an antagonist (phentolamine) were infused intra-arterially to assess α-adrenergic receptor responsiveness and restraint, respectively. Resting MSNA was ∼35% higher in adults with MetSyn (P exercise. Clonidine-mediated vasoconstriction was greater in adults with MetSyn (P  0.05). Interestingly, exercise-mediated vasodilatation was greater in MetSyn (P exercise blood flow during low-intensity hand-grip exercise when compared with age-matched healthy control subjects. These results suggest that adults with MetSyn exhibit compensatory vascular control mechanisms capable of preserving blood flow responses to exercise in the face of augmented sympathetic adrenergic activity. © 2014 The Authors. Experimental Physiology © 2014 The Physiological Society.

  19. Direct numerical simulation of turbulent channel flow with spanwise alternatively distributed strips control

    Science.gov (United States)

    Ni, Weidan; Lu, Lipeng; Fang, Jian; Moulinec, Charles; Yao, Yufeng

    2018-05-01

    The effect of spanwise alternatively distributed strips (SADS) control on turbulent flow in a plane channel has been studied by direct numerical simulations to investigate the characteristics of large-scale streamwise vortices (LSSVs) induced by small-scale active wall actuation, and their potential in suppressing flow separation. SADS control is realized by alternatively arranging out-of-phase control (OPC) and in-phase control (IPC) wall actuations on the lower channel wall surface, in the spanwise direction. It is found that the coherent structures are suppressed or enhanced alternatively by OPC or IPC, respectively, leading to the formation of a vertical shear layer, which is responsible for the LSSVs’ presence. Large-scale low-speed region can also be observed above the OPC strips, which resemble large-scale low-speed streaks. LSSVs are found to be in a statistically-converged steady state and their cores are located between two neighboring OPC and IPC strips. Their motions contribute significantly to the momentum transport in the wall-normal and spanwise directions, demonstrating their potential ability to suppress flow separation.

  20. Passive control of flow structure interaction between a sphere and free-surface

    Directory of Open Access Journals (Sweden)

    Akilli Huseyin

    2012-04-01

    Full Text Available Flow characteristics for both a smooth and a vented sphere such as velocity vectors, patterns of streamlines, vorticity contours, stream-wise fluctuations, cross-stream velocity fluctuations and Reynolds stress correlations between a sphere and free-surface for various submerged ratio at Re =5,000 are studied by using dye visualization and the particle image velocimetry technique. Passive control of flow structure interaction between sphere and free surface was examined by using a modified geometry which has a 15% sphere diameter hole passing through the sphere equator. Both of the spheres were separately placed beneath the free surface with different positions from touching to the free surface to two sphere diameters below the free surface. It is demonstrated that reattachment point of the separated flow to the free surface varies for both of the sphere cases as the sphere position alters vertically through the water flow while the flow structure for the vented sphere occurs considerably symmetrical due to forming of a pair of counter-rotating ring vortices.

  1. A heuristic technique to determine corrective control actions for reactive power flows

    Energy Technology Data Exchange (ETDEWEB)

    Trigo, Angel L.; Martinez, Jose L.; Riquelme, Jesus; Romero, Esther [Department of Electrical Engineering, University of Sevilla (Spain)

    2011-01-15

    This paper presents a sensitivity-based heuristic tool designed to help the system operator in the reactive power flow control problem. The objective of the proposed technique is to determine control actions to ensure that reactive power flows in transmission-subtransmission boundary transformers remain within specified limits, satisfying the new regulatory constraints imposed in most of deregulated markets. With this new constraint the utilities want to guarantee that the utility is able to satisfy its own reactive power requirements, avoiding reactive power flows through long distances in order to reduce the well known disadvantages that reactive power circulation has in the system. A 5-bus tutorial system is used to present the proposed algorithm. The results of the application of the proposed technique to the IEEE 118 buses system and to a regional subtransmission network of the South of Spain are reported and analyzed. In this last actual case, the aim is to maintain reactive power flows in transmission/distribution transformers between those limits set by the Spanish Regulation. A comparison between the proposed tool and a conventional OPF is discussed. (author)

  2. Simulation of process identification and controller tuning for flow control system

    Science.gov (United States)

    Chew, I. M.; Wong, F.; Bono, A.; Wong, K. I.

    2017-06-01

    PID controller is undeniably the most popular method used in controlling various industrial processes. The feature to tune the three elements in PID has allowed the controller to deal with specific needs of the industrial processes. This paper discusses the three elements of control actions and improving robustness of controllers through combination of these control actions in various forms. A plant model is simulated using the Process Control Simulator in order to evaluate the controller performance. At first, the open loop response of the plant is studied by applying a step input to the plant and collecting the output data from the plant. Then, FOPDT of physical model is formed by using both Matlab-Simulink and PRC method. Then, calculation of controller’s setting is performed to find the values of Kc and τi that will give satisfactory control in closed loop system. Then, the performance analysis of closed loop system is obtained by set point tracking analysis and disturbance rejection performance. To optimize the overall physical system performance, a refined tuning of PID or detuning is further conducted to ensure a consistent resultant output of closed loop system reaction to the set point changes and disturbances to the physical model. As a result, the PB = 100 (%) and τi = 2.0 (s) is preferably chosen for setpoint tracking while PB = 100 (%) and τi = 2.5 (s) is selected for rejecting the imposed disturbance to the model. In a nutshell, selecting correlation tuning values is likewise depended on the required control’s objective for the stability performance of overall physical model.

  3. Numerical analysis of the effect of plasma flow control on enhancing the aerodynamic characteristics of stratospheric screw propeller

    International Nuclear Information System (INIS)

    Cheng Yufeng; Nie Wansheng

    2012-01-01

    Based on the body force aerodynamic actuation mechanism of dielectric barrier discharge (DBD) plasma, the effect of plasma flow control on enhancing the aerodynamic characteristics of ten blade elements equably along the stratospheric screw propeller blade was numerical studied. Then the effect of plasma flow control enhancing the aerodynamic characteristics of stratospheric screw propeller was compared that by the blade element theory method. The results show that the flow separate phenomena will easily happen in the root region and top end region of screw propeller, and the blade elements in the root region of screw propeller may work on the negative attack angle condition. DBD plasma flow control can entirely restrain the faintish flow separate phenomena in middle region of screw propeller. Although DBD plasma flow control can not entirely restrain the badly flow separate phenomena in top end region of screw propeller, it also can enhance the aerodynamic characteristics of blade elements in these regions in same degree. But effect of DBD plasma flow control on enhancing the aerodynamic characteristics of the blade elements working on the negative attack angle condition is ineffectively. It can be concluded that DBD plasma flow control can enhance the aerodynamic characteristics of stratospheric screw propeller, the thrust of the whole propeller and the propeller efficiency in the case of plasma on will increases by a factor of 28.27% and 12.3% respectively compared with that in the case of plasma off studied. (authors)

  4. A PSO based unified power flow controller for damping of power system oscillations

    Energy Technology Data Exchange (ETDEWEB)

    Shayeghi, H. [Technical Engineering Dept., Univ. of Mohaghegh Ardabili, Daneshgah Street, P.O. Box 179, Ardabil (Iran); Shayanfar, H.A. [Center of Excellence for Power Automation and Operation, Electrical Engineering Dept., Iran Univ. of Science and Technology, Tehran (Iran); Jalilzadeh, S.; Safari, A. [Technical Engineering Dept., Zanjan Univ., Zanjan (Iran)

    2009-10-15

    On the basis of the linearized Phillips-Herffron model of a single-machine power system, we approach the problem of select the best input control signal of the unified power flow controller (UPFC) and design optimal UPFC based damping controller in order to enhance the damping of the power system low frequency oscillations. The potential of the UPFC supplementary controllers to enhance the dynamic stability is evaluated. This controller is tuned to simultaneously shift the undamped electromechanical modes to a prescribed zone in the s-plane. The problem of robustly UPFC based damping controller is formulated as an optimization problem according to the eigenvalue-based multiobjective function comprising the damping factor, and the damping ratio of the undamped electromechanical modes to be solved using particle swarm optimization technique (PSO) that has a strong ability to find the most optimistic results. To ensure the robustness of the proposed damping controller, the design process takes into account a wide range of operating conditions and system configurations. The effectiveness of the proposed controller is demonstrated through eigenvalue analysis, nonlinear time-domain simulation and some performance indices studies. The results analysis reveals that the tuned PSO based UPFC controller using the proposed multiobjective function has an excellent capability in damping power system low frequency oscillations and enhance greatly the dynamic stability of the power systems. Moreover, the system performance analysis under different operating conditions show that the {delta}{sub E} based controller is superior to the m{sub B} based controller. (author)

  5. Aircraft dual-shaft jet engine with indirect action fuel flow controller

    Science.gov (United States)

    Tudosie, Alexandru-Nicolae

    2017-06-01

    The paper deals with an aircraft single-jet engine's control system, based on a fuel flow controller. Considering the engine as controlled object and its thrust the most important operation effect, from the multitude of engine's parameters only its rotational speed n is measurable and proportional to its thrust, so engine's speed has become the most important controlled parameter. Engine's control system is based on fuel injection Qi dosage, while the output is engine's speed n. Based on embedded system's main parts' mathematical models, the author has described the system by its block diagram with transfer functions; furthermore, some Simulink-Matlab simulations are performed, concerning embedded system quality (its output parameters time behavior) and, meanwhile, some conclusions concerning engine's parameters mutual influences are revealed. Quantitative determinations are based on author's previous research results and contributions, as well as on existing models (taken from technical literature). The method can be extended for any multi-spool engine, single- or twin-jet.

  6. EFFECT OF POWER SUPPLY AND DUTY CONTROL IN CRANKCASE FLOW (CRANKCASE PRESSURE PORT OF ECV

    Directory of Open Access Journals (Sweden)

    MD. IQBAL MAHMUD

    2016-06-01

    Full Text Available The electromagnetic control valve (ECV operated by solenoid in the external variable compressor with the swash plate type is the rising phenomenon. ECV controls the air conditioning compressor for automobile on the basis of the input signal of the pulse width modulation (PWM that supplied from the external controller. PWM technique is used to encode the information for transmission; its main use is to allow the control of the power to be supplied to electrical devices, especially to inertial loads. The mechanism changes the swash plate angle inside the compressor by increasing or reducing the pressure of swash plate chamber by use of the functions of different pressure port within the ECV. Increasing and reducing the swash plate angle finally depends on the solenoid force acting on the rate of supply of current. This research paper investigates the effect of power supply and duty control during the crankcase flowing at Pc pressure port of ECV.

  7. A statistical learning strategy for closed-loop control of fluid flows

    Science.gov (United States)

    Guéniat, Florimond; Mathelin, Lionel; Hussaini, M. Yousuff

    2016-12-01

    This work discusses a closed-loop control strategy for complex systems utilizing scarce and streaming data. A discrete embedding space is first built using hash functions applied to the sensor measurements from which a Markov process model is derived, approximating the complex system's dynamics. A control strategy is then learned using reinforcement learning once rewards relevant with respect to the control objective are identified. This method is designed for experimental configurations, requiring no computations nor prior knowledge of the system, and enjoys intrinsic robustness. It is illustrated on two systems: the control of the transitions of a Lorenz'63 dynamical system, and the control of the drag of a cylinder flow. The method is shown to perform well.

  8. Analysis and Experimental Verification of New Power Flow Control for Grid-Connected Inverter with LCL Filter in Microgrid

    Science.gov (United States)

    Gu, Herong; Guan, Yajuan; Wang, Huaibao; Wei, Baoze; Guo, Xiaoqiang

    2014-01-01

    Microgrid is an effective way to integrate the distributed energy resources into the utility networks. One of the most important issues is the power flow control of grid-connected voltage-source inverter in microgrid. In this paper, the small-signal model of the power flow control for the grid-connected inverter is established, from which it can be observed that the conventional power flow control may suffer from the poor damping and slow transient response. While the new power flow control can mitigate these problems without affecting the steady-state power flow regulation. Results of continuous-domain simulations in MATLAB and digital control experiments based on a 32-bit fixed-point TMS320F2812 DSP are in good agreement, which verify the small signal model analysis and effectiveness of the proposed method. PMID:24672304

  9. Analysis and experimental verification of new power flow control for grid-connected inverter with LCL filter in microgrid.

    Science.gov (United States)

    Gu, Herong; Guan, Yajuan; Wang, Huaibao; Wei, Baoze; Guo, Xiaoqiang

    2014-01-01

    Microgrid is an effective way to integrate the distributed energy resources into the utility networks. One of the most important issues is the power flow control of grid-connected voltage-source inverter in microgrid. In this paper, the small-signal model of the power flow control for the grid-connected inverter is established, from which it can be observed that the conventional power flow control may suffer from the poor damping and slow transient response. While the new power flow control can mitigate these problems without affecting the steady-state power flow regulation. Results of continuous-domain simulations in MATLAB and digital control experiments based on a 32-bit fixed-point TMS320F2812 DSP are in good agreement, which verify the small signal model analysis and effectiveness of the proposed method.

  10. Parametric Study of Synthetic-Jet-Based Flow Control on a Vertical Tail Model

    Science.gov (United States)

    Monastero, Marianne; Lindstrom, Annika; Beyar, Michael; Amitay, Michael

    2015-11-01

    Separation control over the rudder of the vertical tail of a commercial airplane using synthetic-jet-based flow control can lead to a reduction in tail size, with an associated decrease in drag and increase in fuel savings. A parametric, experimental study was undertaken using an array of finite span synthetic jets to investigate the sensitivity of the enhanced vertical tail side force to jet parameters, such as jet spanwise spacing and jet momentum coefficient. A generic wind tunnel model was designed and fabricated to fundamentally study the effects of the jet parameters at varying rudder deflection and model sideslip angles. Wind tunnel results obtained from pressure measurements and tuft flow visualization in the Rensselaer Polytechnic Subsonic Wind Tunnel show a decrease in separation severity and increase in model performance in comparison to the baseline, non-actuated case. The sensitivity to various parameters will be presented.

  11. Petri Nets Based Modelling of Control Flow for Memory-Aid Interactive Programs in Telemedicine

    CERN Document Server

    Khoromskaia, V K

    2004-01-01

    Petri Nets (PN) based modelling of the control flow for the interactive memory assistance programs designed for personal pocket computers and having special requirements for robustness is considered. The proposed concept allows one to elaborate the programs which can give users a variety of possibilities for a day-time planning in the presence of environmental and time restrictions. First, a PN model for a known simple algorithm is constructed and analyzed using the corresponding state equations and incidence matrix. Then a PN graph for a complicated algorithm with overlapping actions and choice possibilities is designed, supplemented by an example of its analysis. Dynamic behaviour of this graph is tested by tracing of all possible paths of the flow of control using the PN simulator. It is shown that PN based modelling provides reliably predictable performance of interactive algorithms with branched structures and concurrency requirements.

  12. Control of multi-evaporator air-conditioning systems for flow distribution

    International Nuclear Information System (INIS)

    Lin, J.-L.; Yeh, T.-J.

    2009-01-01

    Modern air-conditioners incorporate variable-speed compressors and variable-opening expansion valves as the actuators for improving cooling performance and energy efficiency. These actuators have to be properly feedback-controlled; otherwise the systems may exhibit even poorer performance than the conventional machines which use fixed-speed compressors and mechanical expansion valves. In this paper, a control strategy with flow distribution capability is proposed for multi-evaporator air-conditioners to accommodate different thermal demands in different rooms. The structure in the control strategy is based on a low-order, linear model obtained from system identification. To determine appropriate control parameters, theorems regarding stability of the closed-loop system are given. Moreover, by performing steady-state analysis on the control system and utilizing characteristics of the identified system parameters, one can analytically explain the mechanics of flow distribution. Experiments indicate that the proposed strategy can successfully regulate the indoor temperatures regardless that the reference settings for respective rooms are different and the settings are switched in the middle of the control process.

  13. A microfluidic chip for blood plasma separation using electro-osmotic flow control

    International Nuclear Information System (INIS)

    Jiang, Hai; Weng, Xuan; Chon, Chan Hee; Wu, Xudong; Li, Dongqing

    2011-01-01

    In this paper, a microfluidic-based chip with two straight microchannels and five branch microchannels was designed and tested to separate blood plasma from a small sample of fresh human blood. The electro-osmotic flow method was used to control the separation of blood plasma. Blood cell removal and blood plasma extraction were realized in experiments. The efficiency of extracting blood plasma can be as high as 26%

  14. Ultrasound analysis of mental artery flow in elderly patients: a case-control study.

    Science.gov (United States)

    Baladi, Marina G; Tucunduva Neto, Raul R C M; Cortes, Arthur R G; Aoki, Eduardo M; Arita, Emiko S; Freitas, Claudio F

    2015-01-01

    Mental artery flow decreases with age and may have an aetiological role in alveolar ridge atrophy. The aim of this study was to identify factors associated with alterations of mental artery flow, assessed by ultrasonography. This case-control study was conducted on elderly patients (aged above 60 years) at the beginning of dental treatment. Intraoral B-mode Doppler ultrasonography was used to assess mental artery flow. The cases were defined as patients with a weak/absent ultrasound signal, whereas the controls presented a strong ultrasound signal. Demographics and radiographic findings (low bone mineral density on dual-energy X-ray absorptiometry and mandibular cortical index on panoramic radiographs) were analysed as risk factors for weak/absent ultrasound signal and were calculated as adjusted odds ratios (AORs) with 95% confidence intervals (CIs) using conditional logistic regression. In addition, the Student's t-test was used to compare the mean alveolar bone height of the analysed groups. A p-value <0.05 was considered statistically significant. A total of 30 ultrasound examinations (12 cases and 18 controls) were analysed. A weak/absent mental artery pulse strength was significantly associated with edentulism (AOR = 3.67; 95% CI = 0.86-15.63; p = 0.046). In addition, there was a significant difference in alveolar bone height between edentulous cases and controls (p = 0.036). Within the limitations of this study, the present results indicate that edentulism is associated with diminished mental artery flow, which, in turn, affects alveolar bone height.

  15. Ultrasound analysis of mental artery flow in elderly patients: a case–control study

    Science.gov (United States)

    Baladi, Marina G; Tucunduva Neto, Raul R C M; Aoki, Eduardo M; Arita, Emiko S; Freitas, Claudio F

    2015-01-01

    Objectives: Mental artery flow decreases with age and may have an aetiological role in alveolar ridge atrophy. The aim of this study was to identify factors associated with alterations of mental artery flow, assessed by ultrasonography. Methods: This case–control study was conducted on elderly patients (aged above 60 years) at the beginning of dental treatment. Intraoral B-mode Doppler ultrasonography was used to assess mental artery flow. The cases were defined as patients with a weak/absent ultrasound signal, whereas the controls presented a strong ultrasound signal. Demographics and radiographic findings (low bone mineral density on dual-energy X-ray absorptiometry and mandibular cortical index on panoramic radiographs) were analysed as risk factors for weak/absent ultrasound signal and were calculated as adjusted odds ratios (AORs) with 95% confidence intervals (CIs) using conditional logistic regression. In addition, the Student's t-test was used to compare the mean alveolar bone height of the analysed groups. A p-value <0.05 was considered statistically significant. Results: A total of 30 ultrasound examinations (12 cases and 18 controls) were analysed. A weak/absent mental artery pulse strength was significantly associated with edentulism (AOR = 3.67; 95% CI = 0.86–15.63; p = 0.046). In addition, there was a significant difference in alveolar bone height between edentulous cases and controls (p = 0.036). Conclusions: Within the limitations of this study, the present results indicate that edentulism is associated with diminished mental artery flow, which, in turn, affects alveolar bone height. PMID:26205777

  16. Hybrid wind power balance control strategy using thermal power, hydro power and flow batteries

    OpenAIRE

    Gelažanskas, Linas; Baranauskas, Audrius; Gamage, Kelum A.A.; Ažubalis, Mindaugas

    2016-01-01

    The increased number of renewable power plants pose threat to power system balance. Their intermittent nature makes it very difficult to predict power output, thus either additional reserve power plants or new storage and control technologies are required. Traditional spinning reserve cannot fully compensate sudden changes in renewable energy power generation. Using new storage technologies such as flow batteries, it is feasible to balance the variations in power and voltage within very short...

  17. DC microgrid power flow optimization by multi-layer supervision control. Design and experimental validation

    International Nuclear Information System (INIS)

    Sechilariu, Manuela; Wang, Bao Chao; Locment, Fabrice; Jouglet, Antoine

    2014-01-01

    Highlights: • DC microgrid (PV array, storage, power grid connection, DC load) with multi-layer supervision control. • Power balancing following power flow optimization while providing interface for smart grid communication. • Optimization under constraints: storage capability, grid power limitations, grid time-of-use pricing. • Experimental validation of DC microgrid power flow optimization by multi-layer supervision control. • DC microgrid able to perform peak shaving, to avoid undesired injection, and to make full use of locally energy. - Abstract: Urban areas have great potential for photovoltaic (PV) generation, however, direct PV power injection has limitations for high level PV penetration. It induces additional regulations in grid power balancing because of lacking abilities of responding to grid issues such as reducing grid peak consumption or avoiding undesired injections. The smart grid implementation, which is designed to meet these requirements, is facilitated by microgrids development. This paper presents a DC microgrid (PV array, storage, power grid connection, DC load) with multi-layer supervision control which handles instantaneous power balancing following the power flow optimization while providing interface for smart grid communication. The optimization takes into account forecast of PV power production and load power demand, while satisfying constraints such as storage capability, grid power limitations, grid time-of-use pricing and grid peak hour. Optimization, whose efficiency is related to the prediction accuracy, is carried out by mixed integer linear programming. Experimental results show that the proposed microgrid structure is able to control the power flow at near optimum cost and ensures self-correcting capability. It can respond to issues of performing peak shaving, avoiding undesired injection, and making full use of locally produced energy with respect to rigid element constraints

  18. Electrochemical mass-flow control of hydrogen using a fullerene-based proton conductor

    International Nuclear Information System (INIS)

    Maruyama, Ryuichiro

    2002-01-01

    A membrane electrode assembly (MEA) was fabricated using proton conductive hydrogensulfated fullerenol (C 60 (OSO 3 H) n (OH) n ). Rate-controlled mass flow of hydrogen was performed by applying voltage to both electrodes of the MEA without humidification. The amount of the electrochemically transported hydrogen through the MEA increased as the applied current increased, obeying Faraday's law. Residual gas analysis of the transported hydrogen showed that the transported hydrogen contains trace amounts of water less than 1%

  19. Analysis and development of numerical methodologies for simulation of flow control with dielectric barrier discharge actuators

    OpenAIRE

    Abdollahzadehsangroudi, Mohammadmahdi

    2014-01-01

    The aim of this thesis is to investigate and develop different numerical methodologies for modeling the Dielectric Barrier discharge (DBD) plasma actuators for flow control purposes. Two different modeling approaches were considered; one based on Plasma-fluid model and the other based on a phenomenological model. A three component Plasma fluid model based on the transport equations of charged particles was implemented in this thesis in OpenFOAM, using several techniques to redu...

  20. Translating Colored Control Flow Nets into Readable Java via Annotated Java Workflow Nets

    DEFF Research Database (Denmark)

    Lassen, Kristian Bisgaard; Tjell, Simon

    2007-01-01

    In this paper, we present a method for developing Java applications from Colored Control Flow Nets (CCFNs), which is a special kind of Colored Petri Nets (CPNs) that we introduce. CCFN makes an explicit distinction between the representation of: The system, the environment of the system, and the ......In this paper, we present a method for developing Java applications from Colored Control Flow Nets (CCFNs), which is a special kind of Colored Petri Nets (CPNs) that we introduce. CCFN makes an explicit distinction between the representation of: The system, the environment of the system......, and the interface between the system and the environment. Our translation maps CCFNs into Anno- tated Java Workflow Nets (AJWNs) as an intermediate step, and these AJWNs are finally mapped to Java. CCFN is intended to enforce the modeler to describe the system in an imperative manner which makes the subsequent...... translation to Java easier to define. The translation to Java preserves data dependencies and control-flow aspects of the source CCFN. This paper contributes to the model-driven software development paradigm, by showing how to model a system, environment, and their interface, as a CCFN and presenting a fully...

  1. Unsteady supercritical/critical dual flowpath inlet flow and its control methods

    Directory of Open Access Journals (Sweden)

    Jun LIU

    2017-12-01

    Full Text Available The characteristics of unsteady flow in a dual-flowpath inlet, which was designed for a Turbine Based Combined Cycle (TBCC propulsion system, and the control methods of unsteady flow were investigated experimentally and numerically. It was characterized by large-amplitude pressure oscillations and traveling shock waves. As the inlet operated in supercritical condition, namely the terminal shock located in the throat, the shock oscillated, and the period of oscillation was about 50 ms, while the amplitude was 6 mm. The shock oscillation was caused by separation in the diffuser. This shock oscillation can be controlled by extending the length of diffuser which reduces pressure gradient along the flowpath. As the inlet operated in critical condition, namely the terminal shock located at the shoulder of the third compression ramp, the shock oscillated, and the period of oscillation was about 7.5 ms, while the amplitude was 12 mm. At this condition, the shock oscillation was caused by an incompatible backpressure in the bleed region. It can be controlled by increasing the backpressure of the bleed region. Keywords: Airbreathing hypersonic vehicle, Dual flowpath inlet, Terminal shock oscillation, Turbine based combined cycle, Unsteady flow

  2. Biomimetic approaches for green tribology: from the lotus effect to blood flow control

    International Nuclear Information System (INIS)

    Maani, Nazanin; Rayz, Vitaliy S; Nosonovsky, Michael

    2015-01-01

    The research in Green tribology combines several areas including biomimetic tribomaterials and surfaces for controlled adhesion. Biomimetic surfaces mimic living nature and thus they are eco-friendly. The most famous biomimetic surface effect is the Lotus effect (reduction of water adhesion to a solid surface due to micro/nanostructuring of the solid surface). Several extensions of the Lotus effect have been discussed in the literature including the oleophobicity (repelling organic liquids such as oils), underwater oleophobicity to reduce fouling, and the shark skin effect (flow drag reduction due to specially oriented micro-riblets). Here we suggest a potentially important application of micro/nanostructured surfaces in the biomedical area: the micro/nanostructure controlled adhesion in blood flow. Blood is a suspension, and its adhesion properties are different from those of water and oil. For many cardiovascular applications, it is desirable to reduce stagnation and clotting of blood. Therefore, both the underwater oleophobicuity and shark-skin effect can be used. We discuss how computational fluid dynamics models can be used to investigate the structure–property relationships of surface pattern-controlled blood flow adhesion. (paper)

  3. Controlling Heat Transport and Flow Structures in Thermal Turbulence Using Ratchet Surfaces

    Science.gov (United States)

    Jiang, Hechuan; Zhu, Xiaojue; Mathai, Varghese; Verzicco, Roberto; Lohse, Detlef; Sun, Chao

    2018-01-01

    In this combined experimental and numerical study on thermally driven turbulence in a rectangular cell, the global heat transport and the coherent flow structures are controlled with an asymmetric ratchetlike roughness on the top and bottom plates. We show that, by means of symmetry breaking due to the presence of the ratchet structures on the conducting plates, the orientation of the large scale circulation roll (LSCR) can be locked to a preferred direction even when the cell is perfectly leveled out. By introducing a small tilt to the system, we show that the LSCR orientation can be tuned and controlled. The two different orientations of LSCR give two quite different heat transport efficiencies, indicating that heat transport is sensitive to the LSCR direction over the asymmetric roughness structure. Through a quantitative analysis of the dynamics of thermal plume emissions and the orientation of the LSCR over the asymmetric structure, we provide a physical explanation for these findings. The current work has important implications for passive and active flow control in engineering, biofluid dynamics, and geophysical flows.

  4. Nonlinear Slewing Spacecraft Control Based on Exergy, Power Flow, and Static and Dynamic Stability

    Science.gov (United States)

    Robinett, Rush D.; Wilson, David G.

    2009-10-01

    This paper presents a new nonlinear control methodology for slewing spacecraft, which provides both necessary and sufficient conditions for stability by identifying the stability boundaries, rigid body modes, and limit cycles. Conservative Hamiltonian system concepts, which are equivalent to static stability of airplanes, are used to find and deal with the static stability boundaries: rigid body modes. The application of exergy and entropy thermodynamic concepts to the work-rate principle provides a natural partitioning through the second law of thermodynamics of power flows into exergy generator, dissipator, and storage for Hamiltonian systems that is employed to find the dynamic stability boundaries: limit cycles. This partitioning process enables the control system designer to directly evaluate and enhance the stability and performance of the system by balancing the power flowing into versus the power dissipated within the system subject to the Hamiltonian surface (power storage). Relationships are developed between exergy, power flow, static and dynamic stability, and Lyapunov analysis. The methodology is demonstrated with two illustrative examples: (1) a nonlinear oscillator with sinusoidal damping and (2) a multi-input-multi-output three-axis slewing spacecraft that employs proportional-integral-derivative tracking control with numerical simulation results.

  5. Method for controlling power flow between an electrochemical cell and a power grid

    International Nuclear Information System (INIS)

    Coleman, A. K.

    1981-01-01

    A method is disclosed for controlling a force-commutated inverter coupled between an electrochemical cell and a power grid for adjusting the magnitude and direction of the electrical energy flowing therebetween. Both the real power component and the reactive power component of ac electrical energy flow can be independently VARied through the switching waveform presented to the intermediately coupled inverter. A VAR error signal is derived from a comparison of a var command signal with a signal proportional to the actual reactive power circulating between the inverter and the power grid. This signal is presented to a voltage controller which essentially varies only the effective magnitude of the fundamental voltage waveform out of the inverter , thereby leaving the real power component substantially unaffected. In a similar manner, a power error signal is derived by a comparison of a power command signal with a signal proportional to the actual real power flowing between the electrochemical cell and the power grid. This signal is presented to a phase controller which varies only the phase of the fundamental component of the voltage waveform out of the inverter relative to that of the power grid and changes only the real power in proportion thereto, thus leaving the reactive power component substantially unaffected

  6. Development of in-series piezoelectric bimorph bending beam actuators for active flow control applications

    Science.gov (United States)

    Chan, Wilfred K.; Clingman, Dan J.; Amitay, Michael

    2016-04-01

    Piezoelectric materials have long been used for active flow control purposes in aerospace applications to increase the effectiveness of aerodynamic surfaces on aircraft, wind turbines, and more. Piezoelectric actuators are an appropriate choice due to their low mass, small dimensions, simplistic design, and frequency response. This investigation involves the development of piezoceramic-based actuators with two bimorphs placed in series. Here, the main desired characteristic was the achievable displacement amplitude at specific driving voltages and frequencies. A parametric study was performed, in which actuators with varying dimensions were fabricated and tested. These devices were actuated with a sinusoidal waveform, resulting in an oscillating platform on which to mount active flow control devices, such as dynamic vortex generators. The main quantification method consisted of driving these devices with different voltages and frequencies to determine their free displacement, blocking force, and frequency response. It was found that resonance frequency increased with shorter and thicker actuators, while free displacement increased with longer and thinner actuators. Integration of the devices into active flow control test modules is noted. In addition to physical testing, a quasi-static analytical model was developed and compared with experimental data, which showed close correlation for both free displacement and blocking force.

  7. A randomized controlled trial of stretch-and-flow voice therapy for muscle tension dysphonia.

    Science.gov (United States)

    Watts, Christopher R; Hamilton, Amy; Toles, Laura; Childs, Lesley; Mau, Ted

    2015-06-01

    To investigate the effect of stretch-and-flow voice therapy on vocal function and handicap. Randomized controlled trial. Participants with primary muscle tension dysphonia were randomly assigned to experimental or control groups. Experimental participants received vocal hygiene education followed by 6 weeks of stretch-and-flow voice therapy. Control participants received vocal hygiene education only. Outcome variables consisted of a measure of vocal handicap (Voice Handicap Index [VHI]), maximum phonation time, s/z ratio, and acoustic measures. All measures were obtained at baseline prior to treatment and within 2 weeks posttreatment or at the end of the control period. The pre- to posttreatment measurement change (delta Δ) was applied to statistical analyses. A multivariate analysis of variance revealed significant group differences in pre-to-post changes on measures of VHI, maximum phonation time, and cepstral peak prominence (CPP) in connected speech and vowels (P = 0.003, 0.013, 0.025, and 0.017 respectively), with a significant reduction of VHI (Cohen's d = 1.6), increase in maximum phonation time (Cohen's d = 1.2), increase of CPP in connected speech (Cohen's d = 1.2), and increase of CPP in vowels (Cohen's d = 1.1) in the experimental group compared to the control group. This preliminary small sample randomized controlled trial found significantly greater improvement in vocal handicap, maximum phonation time, and acoustic measures of vocal function after participants received stretch-and-flow voice therapy compared to participants receiving vocal hygiene education alone. Additional research incorporating larger samples will be needed to confirm and further investigate these findings. 1b. © 2015 The American Laryngological, Rhinological and Otological Society, Inc.

  8. Cyclooxygenase-2 Selectively Controls Renal Blood Flow Through a Novel PPARβ/δ-Dependent Vasodilator Pathway.

    Science.gov (United States)

    Kirkby, Nicholas S; Sampaio, Walkyria; Etelvino, Gisele; Alves, Daniele T; Anders, Katie L; Temponi, Rafael; Shala, Fisnik; Nair, Anitha S; Ahmetaj-Shala, Blerina; Jiao, Jing; Herschman, Harvey R; Xiaomeng, Wang; Wahli, Walter; Santos, Robson A; Mitchell, Jane A

    2018-02-01

    Cyclooxygenase-2 (COX-2) is an inducible enzyme expressed in inflammation and cancer targeted by nonsteroidal anti-inflammatory drugs. COX-2 is also expressed constitutively in discreet locations where its inhibition drives gastrointestinal and cardiovascular/renal side effects. Constitutive COX-2 expression in the kidney regulates renal function and blood flow; however, the global relevance of the kidney versus other tissues to COX-2-dependent blood flow regulation is not known. Here, we used a microsphere deposition technique and pharmacological COX-2 inhibition to map the contribution of COX-2 to regional blood flow in mice and compared this to COX-2 expression patterns using luciferase reporter mice. Across all tissues studied, COX-2 inhibition altered blood flow predominantly in the kidney, with some effects also seen in the spleen, adipose, and testes. Of these sites, only the kidney displayed appreciable local COX-2 expression. As the main site where COX-2 regulates blood flow, we next analyzed the pathways involved in kidney vascular responses using a novel technique of video imaging small arteries in living tissue slices. We found that the protective effect of COX-2 on renal vascular function was associated with prostacyclin signaling through PPARβ/δ (peroxisome proliferator-activated receptor-β/δ). These data demonstrate the kidney as the principle site in the body where local COX-2 controls blood flow and identifies a previously unreported PPARβ/δ-mediated renal vasodilator pathway as the mechanism. These findings have direct relevance to the renal and cardiovascular side effects of drugs that inhibit COX-2, as well as the potential of the COX-2/prostacyclin/PPARβ/δ axis as a therapeutic target in renal disease. © 2018 The Authors.

  9. Artificial blood-flow controlling effects of inhomogeneity of twisted magnetic fields

    International Nuclear Information System (INIS)

    Nakagawa, Hidenori; Ohuchi, Mikio

    2017-01-01

    We developed a blood-flow controlling system using magnetic therapy for some types of nervous diseases. In our research, we utilized overlapped extremely low frequency (ELF) fields for the most effective blood-flow for the system. Results showed the possibility that the inhomogeneous region obtained by overlapping the fields at 50 Hz, namely, a desirably twisted field revealed a significant difference in induced electromotive forces at the insertion points of electrodes. In addition, ELF exposures with a high inhomogeneity of the twisted field at 50 Hz out of phase were more effective in generating an induced electromotive difference by approximately 31%, as contrasted with the difference generated by the exposure in phase. We expect that the increase of the inhomogeneity of the twisted field around a blood vessel can produce the most effective electromotive difference in the blood, and also moderately affect the excitable cells relating to the autonomic nervous system for an outstanding blood-flow control in vivo. - Highlights: • The principal aim of this research is to contribute to the utilization of the twisted fields for the most effective blood-flow in vivo. • Two newly designed coil systems were used for producing a desirably twisted magnetic field under the measuring domain in the flow channel. • Further, we investigated the magnetohydrodynamic efficiencies of a prototype of a magnetic device, which was converted from use as a commercial alternating magnetic therapy apparatus. • The system was well-constructed with a successful application of a plural exposure coil; therefore, we were able to detect a maximum of induced electromotive force in a fluid of an artificial solution as a substitute for blood. • This new finding demonstrates that the process of blood massotherapy by magnetic stimuli is a therapy for many diseases.

  10. Artificial blood-flow controlling effects of inhomogeneity of twisted magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Nakagawa, Hidenori, E-mail: hnakagawa-tdt@umin.ac.jp; Ohuchi, Mikio

    2017-06-01

    We developed a blood-flow controlling system using magnetic therapy for some types of nervous diseases. In our research, we utilized overlapped extremely low frequency (ELF) fields for the most effective blood-flow for the system. Results showed the possibility that the inhomogeneous region obtained by overlapping the fields at 50 Hz, namely, a desirably twisted field revealed a significant difference in induced electromotive forces at the insertion points of electrodes. In addition, ELF exposures with a high inhomogeneity of the twisted field at 50 Hz out of phase were more effective in generating an induced electromotive difference by approximately 31%, as contrasted with the difference generated by the exposure in phase. We expect that the increase of the inhomogeneity of the twisted field around a blood vessel can produce the most effective electromotive difference in the blood, and also moderately affect the excitable cells relating to the autonomic nervous system for an outstanding blood-flow control in vivo. - Highlights: • The principal aim of this research is to contribute to the utilization of the twisted fields for the most effective blood-flow in vivo. • Two newly designed coil systems were used for producing a desirably twisted magnetic field under the measuring domain in the flow channel. • Further, we investigated the magnetohydrodynamic efficiencies of a prototype of a magnetic device, which was converted from use as a commercial alternating magnetic therapy apparatus. • The system was well-constructed with a successful application of a plural exposure coil; therefore, we were able to detect a maximum of induced electromotive force in a fluid of an artificial solution as a substitute for blood. • This new finding demonstrates that the process of blood massotherapy by magnetic stimuli is a therapy for many diseases.

  11. PIV investigation of the flow induced by a passive surge control method in a radial compressor

    Energy Technology Data Exchange (ETDEWEB)

    Guillou, Erwann; Gancedo, Matthieu; Gutmark, Ephraim [University of Cincinnati, Department of Aerospace Engineering, Cincinnati, OH (United States); Mohamed, Ashraf [Honeywell Turbo Technologies, Greater Los Angeles, CA (United States)

    2012-09-15

    Due to recent emission regulations, the use of turbochargers for force induction of internal combustion engines has increased. Actually, the trend in diesel engines is to downsize the engine by use of turbochargers that operate at higher pressure ratios. Unfortunately, increasing the impeller rotational speed of turbocharger radial compressors tends to reduce their range of operation, which is limited at low mass flow rate by the occurrence of surge. In order to extend the operability of turbochargers, compressor housings can be equipped with a passive surge control device such as a ''ported shroud.'' This specific casing treatment has been demonstrated to enhance the surge margin with minor negative impact on the compressor efficiency. However, the actual working mechanisms of the system remain not well understood. Hence, in order to optimize the design of the ported shroud, it is crucial to identify the dynamic flow changes induced by the implementation of the device to control instabilities. From the full dynamic survey of the compressor performance characteristics obtained with and without ported shroud, specific points of operation were selected to carry out planar flow visualization. At normal working, both standard and stereoscopic particle imaging velocimetry (PIV) measurements were performed to evaluate instantaneous and mean velocity flow fields at the inlet of the compressor. At incipient and full surge, phase-locked PIV measurements were added. As a result, satisfying characterization of the compressor instabilities was provided at different operational speeds. Combining transient pressure data and PIV measurements, the time evolution of the complex flow patterns occurring at surge was reconstructed and a better insight into the bypass mechanism was achieved. (orig.)

  12. PIV investigation of the flow induced by a passive surge control method in a radial compressor

    Science.gov (United States)

    Guillou, Erwann; Gancedo, Matthieu; Gutmark, Ephraim; Mohamed, Ashraf

    2012-09-01

    Due to recent emission regulations, the use of turbochargers for force induction of internal combustion engines has increased. Actually, the trend in diesel engines is to downsize the engine by use of turbochargers that operate at higher pressure ratios. Unfortunately, increasing the impeller rotational speed of turbocharger radial compressors tends to reduce their range of operation, which is limited at low mass flow rate by the occurrence of surge. In order to extend the operability of turbochargers, compressor housings can be equipped with a passive surge control device such as a "ported shroud." This specific casing treatment has been demonstrated to enhance the surge margin with minor negative impact on the compressor efficiency. However, the actual working mechanisms of the system remain not well understood. Hence, in order to optimize the design of the ported shroud, it is crucial to identify the dynamic flow changes induced by the implementation of the device to control instabilities. From the full dynamic survey of the compressor performance characteristics obtained with and without ported shroud, specific points of operation were selected to carry out planar flow visualization. At normal working, both standard and stereoscopic particle imaging velocimetry (PIV) measurements were performed to evaluate instantaneous and mean velocity flow fields at the inlet of the compressor. At incipient and full surge, phase-locked PIV measurements were added. As a result, satisfying characterization of the compressor instabilities was provided at different operational speeds. Combining transient pressure data and PIV measurements, the time evolution of the complex flow patterns occurring at surge was reconstructed and a better insight into the bypass mechanism was achieved.

  13. Impact of Thyristors Controlled Series Capacitor Devices and Optimal Power Flow on Power Systems

    Directory of Open Access Journals (Sweden)

    Fatiha LAKDJA

    2010-12-01

    Full Text Available This paper presents an algorithm, for solving the Optimal Power Flow problem with flexible AC transmission systems (FACTS. The type of FACTS devices is used: thyristor-controlled series capacitor (TCSC. A method to determine the optimal location of thyristor controlled series compensators has been suggested. The proposed approaches have been implemented on an adapted IEEE 26 bus system. The simulation results are discussed to show the performance of the proposed algorithm and our “FACTS programmer “simulator technique, which are compared with TCSC and without TCSC.

  14. A feedback control model for network flow with multiple pure time delays

    Science.gov (United States)

    Press, J.

    1972-01-01

    A control model describing a network flow hindered by multiple pure time (or transport) delays is formulated. Feedbacks connect each desired output with a single control sector situated at the origin. The dynamic formulation invokes the use of differential difference equations. This causes the characteristic equation of the model to consist of transcendental functions instead of a common algebraic polynomial. A general graphical criterion is developed to evaluate the stability of such a problem. A digital computer simulation confirms the validity of such criterion. An optimal decision making process with multiple delays is presented.

  15. Development of a flow controller for long-term sampling of gases and vapors using evacuated canisters.

    Science.gov (United States)

    Rossner, Alan; Farant, Jean Pierre; Simon, Philippe; Wick, David P

    2002-11-15

    Anthropogenic activities contribute to the release of a wide variety of volatile organic compounds (VOC) into microenvironments. Developing and implementing new air sampling technologies that allow for the characterization of exposures to VOC can be useful for evaluating environmental and health concerns arising from such occurrences. A novel air sampler based on the use of a capillary flow controller connected to evacuated canisters (300 mL, 1 and 6 L) was designed and tested. The capillary tube, used to control the flow of air, is a variation on a sharp-edge orifice flow controller. It essentially controls the velocity of the fluid (air) as a function of the properties of the fluid, tube diameter and length. A model to predict flow rate in this dynamic system was developed. The mathematical model presented here was developed using the Hagen-Poiseuille equation and the ideal gas law to predict flow into the canisters used to sample for long periods of time. The Hagen-Poiseuille equation shows the relationship between flow rate, pressure gradient, capillary resistance, fluid viscosity, capillary length and diameter. The flow rates evaluated were extremely low, ranging from 0.05 to 1 mL min(-1). The model was compared with experimental results and was shown to overestimate the flow rate. Empirical equations were developed to more accurately predict flow for the 300 mL, 1 and 6 L canisters used for sampling periods ranging from several hours to one month. The theoretical and observed flow rates for different capillary geometries were evaluated. Each capillary flow controller geometry that was tested was found to generate very reproducible results, RSD gas chromatograph. The capillary flow controller was found to exceed the performance of the sorbent samplers in this comparison.

  16. Control of Vibratory Energy Harvesters in the Presence of Nonlinearities and Power-Flow Constraints

    Science.gov (United States)

    Cassidy, Ian L.

    control the harvester is infeasible due to the high levels of parasitic power required to operate the drive. For the case where a single-directional drive is used, a constraint on the directionality of power-flow is imposed on the system, which necessitates the use of nonlinear feedback. As such, a sub-optimal controller for power-flow-constrained vibratory energy harvesters is presented, which is analytically guaranteed to outperform the optimal static admittance controller. Finally, the last section of this dissertation explores a numerical approach to compute optimal discretized control manifolds for systems with power-flow constraints. Unlike the sub-optimal nonlinear controller, the numerical controller satisfies the necessary conditions for optimality by solving the stochastic Hamilton-Jacobi equation.

  17. An intelligent vehicular traffic signal control system with state flow chart design and fpga prototyping

    International Nuclear Information System (INIS)

    Solangi, U.S.; Memon, T.D.; Noonari, A.S.; Ansari, O.A.

    2017-01-01

    The problem of vehicular traffic congestion is a persistent constraint in the socio-economic development of Pakistan. This paper presents design and implementation of an intelligent traffic controller based on FPGA (Field Programmable Gate Array) to provide an efficient traffic management by optimizing functioning of traffic lights which will result in minimizing traffic congestion at intersections. The existent Traffic Signal system in Pakistan is fixed-time based and offers only Open Loop method for Traffic Control. The Intelligent Traffic Controller presented here uses feedback sensors to read the Traffic density present at a four way intersection to provide an efficient alternative for better supervisory Control of Traffic flow. The traffic density based control logic has been developed in a State Flow Chart for improved visualization of State Machine based operation, and implemented as a Subsystem in Simulink and transferred into VHDL (Hardware Description Language) code using HDL Coder for reducing development time and time to market, which are essential to capitalize Embedded Systems Market. The VHDL code is synthesized with Altera QUARTUS, simulated timing waveform is obtained to verify correctness of the algorithm for different Traffic Scenarios. For implementation purpose estimations were obtained for Cyclone-III and Stratix-III. (author)

  18. An Intelligent Vehicular Traffic Signal Control System with State Flow Chart Design and FPGA Prototyping

    Directory of Open Access Journals (Sweden)

    UMAIR SAEEDSOLANGI

    2017-04-01

    Full Text Available The problem of vehicular traffic congestion is a persistent constraint in the socio-economic development of Pakistan. This paper presents design and implementation of an intelligent traffic controller based on FPGA (Field Programmable Gate Array to provide an efficient traffic management by optimizing functioning of traffic lights which will result in minimizing traffic congestion at intersections. The existent Traffic Signal system in Pakistan is fixed-time based and offers only Open Loop method for Traffic Control. The Intelligent Traffic Controller presented here uses feedback sensors to read the Traffic density present at a four way intersection to provide an efficient alternative for better supervisory Control of Traffic flow. The traffic density based control logic has been developed in a State Flow Chart for improved visualization of State Machine based operation, and implemented as a Subsystem in Simulink and transferred into VHDL (Hardware Description Language code using HDL Coder for reducing development time and time to market, which are essential to capitalize Embedded Systems Market. The VHDL code is synthesized with Altera QUARTUS, simulated timing waveform is obtained to verify correctness of the algorithm for different Traffic Scenarios. For implementation purpose estimations were obtained for Cyclone-III and Stratix-III.

  19. A work process and information flow description of control room operations

    International Nuclear Information System (INIS)

    Davey, E.; Matthews, G.

    2007-01-01

    The control room workplace is the location from which all plant operations are supervised and controlled on a shift-to-shift basis. The activities comprising plant operations are structured into a number of work processes, and information is the common currency that is used to convey work requirements, communicate business and operating decisions, specify work practice, and describe the ongoing plant and work status. This paper describes the motivation for and early experience with developing a work process and information flow model of CANDU control room operations, and discusses some of the insights developed from model examination that suggest ways in which changes in control centre work specification, organization of resources, or asset layout could be undertaken to achieve operational improvements. (author)

  20. Numerical calculation for flow field of servo-tube guided hydraulic control rod driving system

    International Nuclear Information System (INIS)

    He Keyu; Han Weishi

    2010-01-01

    A new-style hydraulic control rod driving mechanism was put forward by using servo-tube control elements for the design of control rod driving mechanism. The results of numerical simulation by CFD program Fluent for flow field of hydraulic driving cylinder indicate that the bigger the outer diameter of servo-tube, the smaller the resistance coefficient of variable throttle orifice. The zero position gap of variable throttle orifice could be determined on 0.2 mm in the design. The pressure difference between the upper and nether surfaces of piston was mainly created by the throttle function of fixed throttle orifice. It can be effectively controlled by changing the gap of variable throttle orifice. And the lift force of driving cylinder is able to meet the requirement on the design load. (authors)