CONTROL AND FAULT DETECTOR CIRCUIT

DOEpatents

Winningstad, C.N.

1958-04-01

A power control and fault detectcr circuit for a radiofrequency system is described. The operation of the circuit controls the power output of a radio- frequency power supply to automatically start the flow of energizing power to the radio-frequency power supply and to gradually increase the power to a predetermined level which is below the point where destruction occurs upon the happening of a fault. If the radio-frequency power supply output fails to increase during such period, the control does not further increase the power. On the other hand, if the output of the radio-frequency power supply properly increases, then the control continues to increase the power to a maximum value. After the maximumn value of radio-frequency output has been achieved. the control is responsive to a ''fault,'' such as a short circuit in the radio-frequency system being driven, so that the flow of power is interrupted for an interval before the cycle is repeated.

Computing an operating parameter of a unified power flow controller

DOEpatents

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.

Computing an operating parameter of a unified power flow controller

DOEpatents

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.

Control voltage and power fluctuations when connecting wind farms

DOE Office of Scientific and Technical Information (OSTI.GOV)

Berinde, Ioan, E-mail: ioan-berinde@yahoo.com; Bălan, Horia, E-mail: hbalan@mail.utcluj.ro; Oros, Teodora Susana, E-mail: teodoraoros-87@yahoo.com

2015-12-23

Voltage, frequency, active power and reactive power are very important parameters in terms of power quality. These parameters are followed when connecting any power plant, the more the connection of wind farms. Connecting wind farms to the electricity system must not cause interference outside the limits set by regulations. Modern solutions for fast and automatic voltage control and power fluctuations using electronic control systems of reactive power flows. FACTS (Flexible Alternating Current Transmision System) systems, established on the basis of power electronic circuits ensure control of electrical status quantities to achieve the necessary transfer of power to the power grid.more » FACTS devices can quickly control parameters and sizes of state power lines, such as impedance line voltages and phase angles of the voltages of the two ends of the line. Their use can lead to improvement in power system operation by increasing the transmission capacity of power lines, power flow control lines, improved static and transient stability reserve.« less

Compare Vehicle Technologies | Transportation Research | NREL

Science.gov Websites

electric car diagramming energy storage, power electronics, and climate control components, as well as storage, power electronics, and climate control components, as well as energy flow among components. 3-D control components, as well as energy flow among components. 3-D illustration of electric car diagramming

Precision control of high temperature furnaces using an auxiliary power supply and charged particle current flow

DOEpatents

Pollock, G.G.

1997-01-28

Two power supplies are combined to control a furnace. A main power supply heats the furnace in the traditional manner, while the power from the auxiliary supply is introduced as a current flow through charged particles existing due to ionized gas or thermionic emission. The main power supply provides the bulk heating power and the auxiliary supply provides a precise and fast power source such that the precision of the total power delivered to the furnace is improved. 5 figs.

Power Flow in Phonation

NASA Astrophysics Data System (ADS)

Zhang, Lucy; Yu, Feimi; Krane, Michael

2017-11-01

The control volume analysis of power flow during sustained phonation is performed using results of a fully-coupled aeroelastic-aeroacoustic simulation. The control volumes consist of the laryngeal region, and the larynx and the vocal tract. Two cases are considered: an effectively infinite length vocal tract, where sound produced in the larynx radiates away and is not reflected back, and a constant-area vocal tract of normal adult human dimensions, in which phonatory sound resonates before radiating from the mouth opening. In both cases the lungs are modeled to absorb all incident sound, while providing a constant volume flow toward the larynx. Control of the acoustic boundary conditions is accomplished using perfectly matched- layers, and flow from the lungs is provided by a source distribution near the entrance to the trachea region. For both cases the power flow for the larynx and larynx plus vocal tract control volumes are computed using the integral form of the mechanical energy equation, expanded to consider power exchanges between slightly compressible flow in the larynx and the acoustic fields in the vocal tract and trachea. The funding from NIH 2R01DC005642-10A1 is greatly acknowledged.

Nonlinear Slewing Spacecraft Control Based on Exergy, Power Flow, and Static and Dynamic Stability

NASA Astrophysics Data System (ADS)

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.

Design of Distributed Controllers Seeking Optimal Power Flow Solutions Under Communication Constraints

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Simonetto, Andrea; Dhople, Sairaj

This paper focuses on power distribution networks featuring inverter-interfaced distributed energy resources (DERs), and develops feedback controllers that drive the DER output powers to solutions of time-varying AC optimal power flow (OPF) problems. Control synthesis is grounded on primal-dual-type methods for regularized Lagrangian functions, as well as linear approximations of the AC power-flow equations. Convergence and OPF-solution-tracking capabilities are established while acknowledging: i) communication-packet losses, and ii) partial updates of control signals. The latter case is particularly relevant since it enables asynchronous operation of the controllers where DER setpoints are updated at a fast time scale based on local voltagemore » measurements, and information on the network state is utilized if and when available, based on communication constraints. As an application, the paper considers distribution systems with high photovoltaic integration, and demonstrates that the proposed framework provides fast voltage-regulation capabilities, while enabling the near real-time pursuit of solutions of AC OPF problems.« less

Design of Distributed Controllers Seeking Optimal Power Flow Solutions under Communication Constraints: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Simonetto, Andrea; Dhople, Sairaj

This paper focuses on power distribution networks featuring inverter-interfaced distributed energy resources (DERs), and develops feedback controllers that drive the DER output powers to solutions of time-varying AC optimal power flow (OPF) problems. Control synthesis is grounded on primal-dual-type methods for regularized Lagrangian functions, as well as linear approximations of the AC power-flow equations. Convergence and OPF-solution-tracking capabilities are established while acknowledging: i) communication-packet losses, and ii) partial updates of control signals. The latter case is particularly relevant since it enables asynchronous operation of the controllers where DER setpoints are updated at a fast time scale based on local voltagemore » measurements, and information on the network state is utilized if and when available, based on communication constraints. As an application, the paper considers distribution systems with high photovoltaic integration, and demonstrates that the proposed framework provides fast voltage-regulation capabilities, while enabling the near real-time pursuit of solutions of AC OPF problems.« less

Power System Transient Stability Improvement by the Interline Power Flow Controller (IPFC)

NASA Astrophysics Data System (ADS)

Zhang, Jun; Yokoyama, Akihiko

This paper presents a study on the power system transient stability improvement by means of interline power flow controller (IPFC). The power injection model of IPFC in transient analysis is proposed and can be easily incorporated into existing power systems. Based on the energy function analysis, the operation of IPFC should guarantee that the time derivative of the global energy of the system is not greater than zero in order to damp the electromechanical oscillations. Accordingly, control laws of IPFC are proposed for its application to the single-machine infinite-bus (SMIB) system and the multimachine systems, respectively. Numerical simulations on the corresponding model power systems are presented to demonstrate their effectiveness in improving power system transient stability.

Description of a MIL-STD-1553B Data Bus Ada Driver for the LeRC EPS Testbed

NASA Technical Reports Server (NTRS)

Mackin, Michael A.

1995-01-01

This document describes the software designed to provide communication between control computers in the NASA Lewis Research Center Electrical Power System Testbed using MIL-STD-1553B. The software drivers are coded in the Ada programming language and were developed on a MSDOS-based computer workstation. The Electrical Power System (EPS) Testbed is a reduced-scale prototype space station electrical power system. The power system manages and distributes electrical power from the sources (batteries or photovoltaic arrays) to the end-user loads. The electrical system primary operates at 120 volts DC, and the secondary system operates at 28 volts DC. The devices which direct the flow of electrical power are controlled by a network of six control computers. Data and control messages are passed between the computers using the MIL-STD-1553B network. One of the computers, the Power Management Controller (PMC), controls the primary power distribution and another, the Load Management Controller (LMC), controls the secondary power distribution. Each of these computers communicates with two other computers which act as subsidiary controllers. These subsidiary controllers are, in turn, connected to the devices which directly control the flow of electrical power.

Indirect current control with separate IZ drop compensation for voltage source converters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kanetkar, V.R.; Dawande, M.S.; Dubey, G.K.

1995-12-31

Indirect Current Control (ICC) of boost type Voltage Source Converters (VSCs) using separate compensation of line IZ voltage drop is presented. A separate bi-directional VSC is used to produce the compensation voltage. This simplifies the ICC regulator scheme as the power flow is controlled through single modulation index. Experimental verification is provided for bi-directional control of the power flow.

Improving Advanced Inverter Control Convergence in Distribution Power Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nagarajan, Adarsh; Palmintier, Bryan; Ding, Fei

Simulation of modern distribution system powerflow increasingly requires capturing the impact of advanced PV inverter voltage regulation on powerflow. With Volt/var control, the inverter adjusts its reactive power flow as a function of the point of common coupling (PCC) voltage. Similarly, Volt/watt control curtails active power production as a function of PCC voltage. However, with larger systems and higher penetrations of PV, this active/reactive power flow itself can cause significant changes to the PCC voltage potentially introducing oscillations that slow the convergence of system simulations. Improper treatment of these advanced inverter functions could potentially lead to incorrect results. This papermore » explores a simple approach to speed such convergence by blending in the previous iteration's reactive power estimate to dampen these oscillations. Results with a single large (5MW) PV system and with multiple 500kW advanced inverters show dramatic improvements using this approach.« less

Hybrid Method for Power Control Simulation of a Single Fluid Plasma Thruster

NASA Astrophysics Data System (ADS)

Jaisankar, S.; Sheshadri, T. S.

2018-05-01

Propulsive plasma flow through a cylindrical-conical diverging thruster is simulated by a power controlled hybrid method to obtain the basic flow, thermodynamic and electromagnetic variables. Simulation is based on a single fluid model with electromagnetics being described by the equations of potential Poisson, Maxwell and the Ohm's law while the compressible fluid dynamics by the Navier Stokes in cylindrical form. The proposed method solved the electromagnetics and fluid dynamics separately, both to segregate the two prominent scales for an efficient computation and for the delivery of voltage controlled rated power. The magnetic transport is solved for steady state while fluid dynamics is allowed to evolve in time along with an electromagnetic source using schemes based on generalized finite difference discretization. The multistep methodology with power control is employed for simulating fully ionized propulsive flow of argon plasma through the thruster. Numerical solution shows convergence of every part of the solver including grid stability causing the multistep hybrid method to converge for a rated power delivery. Simulation results are reasonably in agreement with the reported physics of plasma flow in the thruster thus indicating the potential utility of this hybrid computational framework, especially when single fluid approximation of plasma is relevant.

Control of Vibratory Energy Harvesters in the Presence of Nonlinearities and Power-Flow Constraints

NASA Astrophysics Data System (ADS)

Cassidy, Ian L.

Over the past decade, a significant amount of research activity has been devoted to developing electromechanical systems that can convert ambient mechanical vibrations into usable electric power. Such systems, referred to as vibratory energy harvesters, have a number of useful of applications, ranging in scale from self-powered wireless sensors for structural health monitoring in bridges and buildings to energy harvesting from ocean waves. One of the most challenging aspects of this technology concerns the efficient extraction and transmission of power from transducer to storage. Maximizing the rate of power extraction from vibratory energy harvesters is further complicated by the stochastic nature of the disturbance. The primary purpose of this dissertation is to develop feedback control algorithms which optimize the average power generated from stochastically-excited vibratory energy harvesters. This dissertation will illustrate the performance of various controllers using two vibratory energy harvesting systems: an electromagnetic transducer embedded within a flexible structure, and a piezoelectric bimorph cantilever beam. Compared with piezoelectric systems, large-scale electromagnetic systems have received much less attention in the literature despite their ability to generate power at the watt--kilowatt scale. Motivated by this observation, the first part of this dissertation focuses on developing an experimentally validated predictive model of an actively controlled electromagnetic transducer. Following this experimental analysis, linear-quadratic-Gaussian control theory is used to compute unconstrained state feedback controllers for two ideal vibratory energy harvesting systems. This theory is then augmented to account for competing objectives, nonlinearities in the harvester dynamics, and non-quadratic transmission loss models in the electronics. In many vibratory energy harvesting applications, employing a bi-directional power electronic drive to actively 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.

Comparison of control structures for a bidirectional high-frequency dc-dc converter

NASA Astrophysics Data System (ADS)

Himmelstoss, Felix A.; Kolar, Johann W.; Zach, Franz C.

1989-08-01

A system for dc-dc power conversion based on a buck-boost converter topology is presented. It makes power flow in both directions possible. The possibility of bidirectional power flow is useful for certain applications, such as uninterruptable power supplies. Starting from a structural diagram the transfer function of the system is derived. The controller for the converter is then designed. It is made up of a simple voltage controller, a voltage controller with an inner loop current controller (cascade control) and with two kinds of state space control. The transfer functions of the different system parts are derived and dimensioning guidelines for the controller sections are presented. The closed loop behavior of the bidirectional converter for the different control structures is analyzed based on simulation using duty cycle averaging. Bodediagrams and step responses are shown.

Photovoltaic Inverter Controllers Seeking AC Optimal Power Flow Solutions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.

This paper considers future distribution networks featuring inverter-interfaced photovoltaic (PV) systems, and addresses the synthesis of feedback controllers that seek real- and reactive-power inverter setpoints corresponding to AC optimal power flow (OPF) solutions. The objective is to bridge the temporal gap between long-term system optimization and real-time inverter control, and enable seamless PV-owner participation without compromising system efficiency and stability. The design of the controllers is grounded on a dual ..epsilon..-subgradient method, while semidefinite programming relaxations are advocated to bypass the non-convexity of AC OPF formulations. Global convergence of inverter output powers is analytically established for diminishing stepsize rules formore » cases where: i) computational limits dictate asynchronous updates of the controller signals, and ii) inverter reference inputs may be updated at a faster rate than the power-output settling time.« less

Control system of an excitation power supply for fast axial flow CO2 lasersupda

NASA Astrophysics Data System (ADS)

Li, Bo; Jia, Xinting; Yuan, Hao; Gao, Yuhu; Wang, Youqing

2009-08-01

A switching power control system of fast axial flow CO2 lasers based on DSP is presented. The key techniques are described in detail, include the control principle, realization method and program design. The experiment showed that the system make the laser discharge stably and work in multi-mode. The discharge current can be adjusted from 3mA to 85mA continuously. 20-2000Hz frequency, 0-100% duty cycle laser pulse is achieved. The power supply can improve the processing efficiency and quality.

Microgravity Fluid Separation Physics: Experimental and Analytical Results

NASA Technical Reports Server (NTRS)

Shoemaker, J. Michael; Schrage, Dean S.

1997-01-01

Effective, low power, two-phase separation systems are vital for the cost-effective study and utilization of two-phase flow systems and flow physics of two-phase flows. The study of microgravity flows have the potential to reveal significant insight into the controlling mechanisms for the behavior of flows in both normal and reduced gravity environments. The microgravity environment results in a reduction in gravity induced buoyancy forces acting on the discrete phases. Thus, surface tension, viscous, and inertial forces exert an increased influence on the behavior of the flow as demonstrated by the axisymmetric flow patterns. Several space technology and operations groups have studied the flow behavior in reduced gravity since gas-liquid flows are encountered in several systems such as cabin humidity control, wastewater treatment, thermal management, and Rankine power systems.

System and method for networking electrochemical devices

DOEpatents

Williams, Mark C.; Wimer, John G.; Archer, David H.

1995-01-01

An improved electrochemically active system and method including a plurality of electrochemical devices, such as fuel cells and fluid separation devices, in which the anode and cathode process-fluid flow chambers are connected in fluid-flow arrangements so that the operating parameters of each of said plurality of electrochemical devices which are dependent upon process-fluid parameters may be individually controlled to provide improved operating efficiency. The improvements in operation include improved power efficiency and improved fuel utilization in fuel cell power generating systems and reduced power consumption in fluid separation devices and the like through interstage process fluid parameter control for series networked electrochemical devices. The improved networking method includes recycling of various process flows to enhance the overall control scheme.

Asymmetrical booster ascent guidance and control system design study. Volume 5: Space shuttle powered explicit guidance. [space shuttle development

NASA Technical Reports Server (NTRS)

Jaggers, R. F.

1974-01-01

An optimum powered explicit guidance algorithm capable of handling all space shuttle exoatospheric maneuvers is presented. The theoretical and practical basis for the currently baselined space shuttle powered flight guidance equations and logic is documented. Detailed flow diagrams for implementing the steering computations for all shuttle phases, including powered return to launch site (RTLS) abort, are also presented. Derivation of the powered RTLS algorithm is provided, as well as detailed flow diagrams for implementing the option. The flow diagrams and equations are compatible with the current powered flight documentation.

Optimal Operation and Management for Smart Grid Subsumed High Penetration of Renewable Energy, Electric Vehicle, and Battery Energy Storage System

NASA Astrophysics Data System (ADS)

Shigenobu, Ryuto; Noorzad, Ahmad Samim; Muarapaz, Cirio; Yona, Atsushi; Senjyu, Tomonobu

2016-04-01

Distributed generators (DG) and renewable energy sources have been attracting special attention in distribution systems in all over the world. Renewable energies, such as photovoltaic (PV) and wind turbine generators are considered as green energy. However, a large amount of DG penetration causes voltage deviation beyond the statutory range and reverse power flow at interconnection points in the distribution system. If excessive voltage deviation occurs, consumer's electric devices might break and reverse power flow will also has a negative impact on the transmission system. Thus, mass interconnections of DGs has an adverse effect on both of the utility and the customer. Therefore, reactive power control method is proposed previous research by using inverters attached DGs for prevent voltage deviations. Moreover, battery energy storage system (BESS) is also proposed for resolve reverse power flow. In addition, it is possible to supply high quality power for managing DGs and BESSs. Therefore, this paper proposes a method to maintain voltage, active power, and reactive power flow at interconnection points by using cooperative controlled of PVs, house BESSs, EVs, large BESSs, and existing voltage control devices. This paper not only protect distribution system, but also attain distribution loss reduction and effectivity management of control devices. Therefore mentioned control objectives are formulated as an optimization problem that is solved by using the Particle Swarm Optimization (PSO) algorithm. Modified scheduling method is proposed in order to improve convergence probability of scheduling scheme. The effectiveness of the proposed method is verified by case studies results and by using numerical simulations in MATLAB®.

An integrated power/attitude control system /IPACS/ for space vehicle application

NASA Technical Reports Server (NTRS)

Anderson, W. W.; Keckler, C. R.

1973-01-01

An integrated power and attitude control system (IPACS) concept with potential application to a broad class of space missions is discussed. The concept involves the storage and supply on demand of electrical energy in rotating flywheels while simultaneously providing control torques by controlled precession of the flywheels. The system is thus an alternative to the storage batteries used on present spacecraft while providing similar capability for attitude control as that represented by a control moment gyroscope (CMG) system. Potential IPACS configurations discussed include single- and double-rotor double-gimbal IPACS units. Typical sets of control laws which would manage the momentum and energy exchange between the IPACS and a typical space vehicle are discussed. Discussion of a simulation of a typical potential IPACS configuration and candidate mission concerned with pointing capability, power supply and demand flow, and discussion of the interactions between stabilization and control requirements and power flow requirements are presented.

Primary-Side Power Flow Control of Wireless Power Transfer for Electric Vehicle Charging

DOE PAGES

Miller, John M.; Onar, Omer C.; Chinthavali, Madhu

2014-12-22

Various noncontacting methods of plug-in electric vehicle charging are either under development or now deployed as aftermarket options in the light-duty automotive market. Wireless power transfer (WPT) is now the accepted term for wireless charging and is used synonymously for inductive power transfer and magnetic resonance coupling. WPT technology is in its infancy; standardization is lacking, especially on interoperability, center frequency selection, magnetic fringe field suppression, and the methods employed for power flow regulation. This paper proposes a new analysis concept for power flow in WPT in which the primary provides frequency selection and the tuned secondary, with its resemblancemore » to a power transmission network having a reactive power voltage control, is analyzed as a transmission network. Analysis is supported with experimental data taken from Oak Ridge National Laboratory s WPT apparatus. Lastly, this paper also provides an experimental evidence for frequency selection, fringe field assessment, and the need for low-latency communications in the feedback path.« less

Methods of computing steady-state voltage stability margins of power systems

DOEpatents

Chow, Joe Hong; Ghiocel, Scott Gordon

2018-03-20

In steady-state voltage stability analysis, as load increases toward a maximum, conventional Newton-Raphson power flow Jacobian matrix becomes increasingly ill-conditioned so power flow fails to converge before reaching maximum loading. A method to directly eliminate this singularity reformulates the power flow problem by introducing an AQ bus with specified bus angle and reactive power consumption of a load bus. For steady-state voltage stability analysis, the angle separation between the swing bus and AQ bus can be varied to control power transfer to the load, rather than specifying the load power itself. For an AQ bus, the power flow formulation is only made up of a reactive power equation, thus reducing the size of the Jacobian matrix by one. This reduced Jacobian matrix is nonsingular at the critical voltage point, eliminating a major difficulty in voltage stability analysis for power system operations.

Coordinating IMC-PID and adaptive SMC controllers for a PEMFC.

PubMed

Wang, Guo-Liang; Wang, Yong; Shi, Jun-Hai; Shao, Hui-He

2010-01-01

For a Proton Exchange Membrane Fuel Cell (PEMFC) power plant with a methanol reformer, the process parameters and power output are considered simultaneously to avoid violation of the constraints and to keep the fuel cell power plant safe and effective. In this paper, a novel coordinating scheme is proposed by combining an Internal Model Control (IMC) based PID Control and adaptive Sliding Mode Control (SMC). The IMC-PID controller is designed for the reformer of the fuel flow rate according to the expected first-order dynamic properties. The adaptive SMC controller of the fuel cell current has been designed using the constant plus proportional rate reaching law. The parameters of the SMC controller are adaptively tuned according to the response of the fuel flow rate control system. When the power output controller feeds back the current references to these two controllers, the coordinating controllers system works in a system-wide way. The simulation results of the PEMFC power plant demonstrate the effectiveness of the proposed method. 2009 ISA. Published by Elsevier Ltd. All rights reserved.

Development of Android based Smart Power Saving System

NASA Astrophysics Data System (ADS)

Gupta, Ashutosh; Kumar, Pradeep; Ghosh, Tathagata; Bhawna, Shruthi. S.

2017-08-01

An android based smart power saving system has been presented in this paper. For this purpose, an application is developed for controlling the intensity of an AC supply using a dimmer circuit in android platform and to monitor the current flow on different intensity level a current sensor is used in the circuit. Dimmer circuit provides a 16-different intensity level to control the flow of current and help in power saving. The system is very simple and robust as it is based on android platform.

Impute DC link (IDCL) cell based power converters and control thereof

DOEpatents

Divan, Deepakraj M.; Prasai, Anish; Hernendez, Jorge; Moghe, Rohit; Iyer, Amrit; Kandula, Rajendra Prasad

2016-04-26

Power flow controllers based on Imputed DC Link (IDCL) cells are provided. The IDCL cell is a self-contained power electronic building block (PEBB). The IDCL cell may be stacked in series and parallel to achieve power flow control at higher voltage and current levels. Each IDCL cell may comprise a gate drive, a voltage sharing module, and a thermal management component in order to facilitate easy integration of the cell into a variety of applications. By providing direct AC conversion, the IDCL cell based AC/AC converters reduce device count, eliminate the use of electrolytic capacitors that have life and reliability issues, and improve system efficiency compared with similarly rated back-to-back inverter system.

Flow Control in Wells Turbines for Harnessing Maximum Wave Power.

PubMed

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.

Flow Control in Wells Turbines for Harnessing Maximum Wave Power

PubMed Central

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

Optimal Water-Power Flow Problem: Formulation and Distributed Optimal Solution

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall-Anese, Emiliano; Zhao, Changhong; Zamzam, Admed S.

This paper formalizes an optimal water-power flow (OWPF) problem to optimize the use of controllable assets across power and water systems while accounting for the couplings between the two infrastructures. Tanks and pumps are optimally managed to satisfy water demand while improving power grid operations; {for the power network, an AC optimal power flow formulation is augmented to accommodate the controllability of water pumps.} Unfortunately, the physics governing the operation of the two infrastructures and coupling constraints lead to a nonconvex (and, in fact, NP-hard) problem; however, after reformulating OWPF as a nonconvex, quadratically-constrained quadratic problem, a feasible point pursuit-successivemore » convex approximation approach is used to identify feasible and optimal solutions. In addition, a distributed solver based on the alternating direction method of multipliers enables water and power operators to pursue individual objectives while respecting the couplings between the two networks. The merits of the proposed approach are demonstrated for the case of a distribution feeder coupled with a municipal water distribution network.« less

A power autonomous monopedal robot

NASA Astrophysics Data System (ADS)

Krupp, Benjamin T.; Pratt, Jerry E.

2006-05-01

We present the design and initial results of a power-autonomous planar monopedal robot. The robot is a gasoline powered, two degree of freedom robot that runs in a circle, constrained by a boom. The robot uses hydraulic Series Elastic Actuators, force-controllable actuators which provide high force fidelity, moderate bandwidth, and low impedance. The actuators are mounted in the body of the robot, with cable drives transmitting power to the hip and knee joints of the leg. A two-stroke, gasoline engine drives a constant displacement pump which pressurizes an accumulator. Absolute position and spring deflection of each of the Series Elastic Actuators are measured using linear encoders. The spring deflection is translated into force output and compared to desired force in a closed loop force-control algorithm implemented in software. The output signal of each force controller drives high performance servo valves which control flow to each of the pistons of the actuators. In designing the robot, we used a simulation-based iterative design approach. Preliminary estimates of the robot's physical parameters were based on past experience and used to create a physically realistic simulation model of the robot. Next, a control algorithm was implemented in simulation to produce planar hopping. Using the joint power requirements and range of motions from simulation, we worked backward specifying pulley diameter, piston diameter and stroke, hydraulic pressure and flow, servo valve flow and bandwidth, gear pump flow, and engine power requirements. Components that meet or exceed these specifications were chosen and integrated into the robot design. Using CAD software, we calculated the physical parameters of the robot design, replaced the original estimates with the CAD estimates, and produced new joint power requirements. We iterated on this process, resulting in a design which was prototyped and tested. The Monopod currently runs at approximately 1.2 m/s with the weight of all the power generating components, but powered from an off-board pump. On a test stand, the eventual on-board power system generates enough pressure and flow to meet the requirements of these runs and we are currently integrating the power system into the real robot. When operated from an off-board system without carrying the weight of the power generating components, the robot currently runs at approximately 2.25 m/s. Ongoing work is focused on integrating the power system into the robot, improving the control algorithm, and investigating methods for improving efficiency.

DOSE CONTROLLER FOR AGUACLARA WATER TREATMENT PLANTS

EPA Science Inventory

The expected results include a proven design for a gravity powered dose controller that works for calcium hypochlorite or aluminum sulfate solutions. The dose controller will be coupled with plant flow rate measuring systems that have compatible relationships between flow rate...

Application of PSAT to Load Flow Analysis with STATCOM under Load Increase Scenario and Line Contingencies

NASA Astrophysics Data System (ADS)

Telang, Aparna S.; Bedekar, P. P.

2017-09-01

Load flow analysis is the initial and essential step for any power system computation. It is required for choosing better options for power system expansion to meet with ever increasing load demand. Implementation of Flexible AC Transmission System (FACTS) device like STATCOM, in the load flow, which is having fast and very flexible control, is one of the important tasks for power system researchers. This paper presents a simple and systematic approach for steady state power flow calculations with FACTS controller, static synchronous compensator (STATCOM) using command line usage of MATLAB tool-power system analysis toolbox (PSAT). The complexity of MATLAB language programming increases due to incorporation of STATCOM in an existing Newton-Raphson load flow algorithm. Thus, the main contribution of this paper is to show how command line usage of user friendly MATLAB tool, PSAT, can extensively be used for quicker and wider interpretation of the results of load flow with STATCOM. The novelty of this paper lies in the method of applying the load increase pattern, where the active and reactive loads have been changed simultaneously at all the load buses under consideration for creating stressed conditions for load flow analysis with STATCOM. The performance have been evaluated on many standard IEEE test systems and the results for standard IEEE-30 bus system, IEEE-57 bus system, and IEEE-118 bus system are presented.

Analysis of Operating Modes of Stand-Alone Series Controller of Power Flows for Overhead Power Transmission Lines

NASA Astrophysics Data System (ADS)

Astashev, M. G.; Panfilov, D. I.; Seregin, D. A.; Chernyshev, A. A.

2017-12-01

The features of using the bridge voltage inverter in small-size stand-alone series controllers of power flows (PFSC) for overhead power transmission lines (OPTL) are examined. The basic processes in the converter during transient and steady state modes were analyzed. The basic relations for calculating the electromagnetic processes taking into account the energy loss in the circuit and without it were received. A simulation model is proposed of a converter that makes it possible to study its operating modes during the formation of reactance introduced into the overhead power transmission line. The results of simulation of operating modes of the PFSC are presented.

Clustering execution in a processing system to increase power savings

DOEpatents

Bose, Pradip; Buyuktosunoglu, Alper; Jacobson, Hans M.; Vega, Augusto J.

2018-03-20

Embodiments relate to clustering execution in a processing system. An aspect includes accessing a control flow graph that defines a data dependency and an execution sequence of a plurality of tasks of an application that executes on a plurality of system components. The execution sequence of the tasks in the control flow graph is modified as a clustered control flow graph that clusters active and idle phases of a system component while maintaining the data dependency. The clustered control flow graph is sent to an operating system, where the operating system utilizes the clustered control flow graph for scheduling the tasks.

Study on emergency power control strategy for AC/DC hybrid power system containing VSC-HVDC

NASA Astrophysics Data System (ADS)

Liu, Lin; Hu, Zhenda; Ye, Rong; Lin, Zhangsui; Yang, Xiaodong; Yi, Yang

2018-04-01

This paper presents a comprehensive emergency power control strategy for AC/DC hybrid power systems containing VSC-HVDC. Firstly, the paper analyzes the power support of the VSC-HVDC to the AC lines using the Power Transferring Relativity Factor (PTRF). Then the power adjustment of the VSC-HVDC in several different circumstances are calculated. Finally, the online power control strategies of VSC-HVDC are designed, which could rapidly control the power of the VSC-HVDC, keeping the power flow of AC lines below the upper limit. Furthermore, the strategy is proven to be effective by the simulations with EMTDC/PSCAD.

Real-Time Load-Side Control of Electric Power Systems

NASA Astrophysics Data System (ADS)

Zhao, Changhong

Two trends are emerging from modern electric power systems: the growth of renewable (e.g., solar and wind) generation, and the integration of information technologies and advanced power electronics. The former introduces large, rapid, and random fluctuations in power supply, demand, frequency, and voltage, which become a major challenge for real-time operation of power systems. The latter creates a tremendous number of controllable intelligent endpoints such as smart buildings and appliances, electric vehicles, energy storage devices, and power electronic devices that can sense, compute, communicate, and actuate. Most of these endpoints are distributed on the load side of power systems, in contrast to traditional control resources such as centralized bulk generators. This thesis focuses on controlling power systems in real time, using these load side resources. Specifically, it studies two problems. (1) Distributed load-side frequency control: We establish a mathematical framework to design distributed frequency control algorithms for flexible electric loads. In this framework, we formulate a category of optimization problems, called optimal load control (OLC), to incorporate the goals of frequency control, such as balancing power supply and demand, restoring frequency to its nominal value, restoring inter-area power flows, etc., in a way that minimizes total disutility for the loads to participate in frequency control by deviating from their nominal power usage. By exploiting distributed algorithms to solve OLC and analyzing convergence of these algorithms, we design distributed load-side controllers and prove stability of closed-loop power systems governed by these controllers. This general framework is adapted and applied to different types of power systems described by different models, or to achieve different levels of control goals under different operation scenarios. We first consider a dynamically coherent power system which can be equivalently modeled with a single synchronous machine. We then extend our framework to a multi-machine power network, where we consider primary and secondary frequency controls, linear and nonlinear power flow models, and the interactions between generator dynamics and load control. (2) Two-timescale voltage control: The voltage of a power distribution system must be maintained closely around its nominal value in real time, even in the presence of highly volatile power supply or demand. For this purpose, we jointly control two types of reactive power sources: a capacitor operating at a slow timescale, and a power electronic device, such as a smart inverter or a D-STATCOM, operating at a fast timescale. Their control actions are solved from optimal power flow problems at two timescales. Specifically, the slow-timescale problem is a chance-constrained optimization, which minimizes power loss and regulates the voltage at the current time instant while limiting the probability of future voltage violations due to stochastic changes in power supply or demand. This control framework forms the basis of an optimal sizing problem, which determines the installation capacities of the control devices by minimizing the sum of power loss and capital cost. We develop computationally efficient heuristics to solve the optimal sizing problem and implement real-time control. Numerical experiments show that the proposed sizing and control schemes significantly improve the reliability of voltage control with a moderate increase in cost.

Feedwater temperature control methods and systems

DOEpatents

Moen, Stephan Craig; Noonan, Jack Patrick; Saha, Pradip

2014-04-22

A system for controlling the power level of a natural circulation boiling water nuclear reactor (NCBWR) is disclosed. The system, in accordance with an example embodiment of the present invention, may include a controller configured to control a power output level of the NCBWR by controlling a heating subsystem to adjust a temperature of feedwater flowing into an annulus of the NCBWR. The heating subsystem may include a steam diversion line configured to receive steam generated by a core of the NCBWR and a steam bypass valve configured to receive commands from the controller to control a flow of the steam in the steam diversion line, wherein the steam received by the steam diversion line has not passed through a turbine. Additional embodiments of the invention may include a feedwater bypass valve for controlling an amount of flow of the feedwater through a heater bypass line to the annulus.

Vibrational Power Flow Analysis of Rods and Beams

NASA Technical Reports Server (NTRS)

Wohlever, James Christopher; Bernhard, R. J.

1988-01-01

A new method to model vibrational power flow and predict the resulting energy density levels in uniform rods and beams is investigated. This method models the flow of vibrational power in a manner analogous to the flow of thermal power in a heat conduction problem. The classical displacement solutions for harmonically excited, hysteretically damped rods and beams are used to derive expressions for the vibrational power flow and energy density in the rod and beam. Under certain conditions, the power flow in these two structural elements will be shown to be proportional to the energy density gradient. Using the relationship between power flow and energy density, an energy balance on differential control volumes in the rod and beam leads to a Poisson's equation which models the energy density distribution in the rod and beam. Coupling the energy density and power flow solutions for rods and beams is also discussed. It is shown that the resonant behavior of finite structures complicates the coupling of solutions, especially when the excitations are single frequency inputs. Two coupling formulations are discussed, the first based on the receptance method, and the second on the travelling wave approach used in Statistical Energy Analysis. The receptance method is the more computationally intensive but is capable of analyzing single frequency excitation cases. The traveling wave approach gives a good approximation of the frequency average of energy density and power flow in coupled systems, and thus, is an efficient technique for use with broadband frequency excitation.

Deep Learning-Based Data Forgery Detection in Automatic Generation Control

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Fengli; Li, Qinghua

Automatic Generation Control (AGC) is a key control system in the power grid. It is used to calculate the Area Control Error (ACE) based on frequency and tie-line power flow between balancing areas, and then adjust power generation to maintain the power system frequency in an acceptable range. However, attackers might inject malicious frequency or tie-line power flow measurements to mislead AGC to do false generation correction which will harm the power grid operation. Such attacks are hard to be detected since they do not violate physical power system models. In this work, we propose algorithms based on Neural Networkmore » and Fourier Transform to detect data forgery attacks in AGC. Different from the few previous work that rely on accurate load prediction to detect data forgery, our solution only uses the ACE data already available in existing AGC systems. In particular, our solution learns the normal patterns of ACE time series and detects abnormal patterns caused by artificial attacks. Evaluations on the real ACE dataset show that our methods have high detection accuracy.« less

Variable-Displacement Hydraulic Drive Unit

NASA Technical Reports Server (NTRS)

Lang, D. J.; Linton, D. J.; Markunas, A.

1986-01-01

Hydraulic power controlled through multiple feedback loops. In hydraulic drive unit, power closely matched to demand, thereby saving energy. Hydraulic flow to and from motor adjusted by motor-control valve connected to wobbler. Wobbler angle determines motor-control-valve position, which in turn determines motor displacement. Concept applicable to machine tools, aircraft controls, and marine controls.

A Survey of Distributed Optimization and Control Algorithms for Electric Power Systems

DOE PAGES

Molzahn, Daniel K.; Dorfler, Florian K.; Sandberg, Henrik; ...

2017-07-25

Historically, centrally computed algorithms have been the primary means of power system optimization and control. With increasing penetrations of distributed energy resources requiring optimization and control of power systems with many controllable devices, distributed algorithms have been the subject of significant research interest. Here, this paper surveys the literature of distributed algorithms with applications to optimization and control of power systems. In particular, this paper reviews distributed algorithms for offline solution of optimal power flow (OPF) problems as well as online algorithms for real-time solution of OPF, optimal frequency control, optimal voltage control, and optimal wide-area control problems.

A Survey of Distributed Optimization and Control Algorithms for Electric Power Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Molzahn, Daniel K.; Dorfler, Florian K.; Sandberg, Henrik

Historically, centrally computed algorithms have been the primary means of power system optimization and control. With increasing penetrations of distributed energy resources requiring optimization and control of power systems with many controllable devices, distributed algorithms have been the subject of significant research interest. Here, this paper surveys the literature of distributed algorithms with applications to optimization and control of power systems. In particular, this paper reviews distributed algorithms for offline solution of optimal power flow (OPF) problems as well as online algorithms for real-time solution of OPF, optimal frequency control, optimal voltage control, and optimal wide-area control problems.

Flow-Control Unit For Nitrogen And Hydrogen Gases

NASA Technical Reports Server (NTRS)

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.

Clustering execution in a processing system to increase power savings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bose, Pradip; Buyuktosunoglu, Alper; Jacobson, Hans M.

Embodiments relate to clustering execution in a processing system. An aspect includes accessing a control flow graph that defines a data dependency and an execution sequence of a plurality of tasks of an application that executes on a plurality of system components. The execution sequence of the tasks in the control flow graph is modified as a clustered control flow graph that clusters active and idle phases of a system component while maintaining the data dependency. The clustered control flow graph is sent to an operating system, where the operating system utilizes the clustered control flow graph for scheduling themore » tasks.« less

Thaw flow control for liquid heat transport systems

DOEpatents

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.

High power gas laser - Applications and future developments

NASA Technical Reports Server (NTRS)

Hertzberg, A.

1977-01-01

Fast flow can be used to create the population inversion required for lasing action, or can be used to improve laser operation, for example by the removal of waste heat. It is pointed out that at the present time all lasers which are capable of continuous high-average power employ flow as an indispensable aspect of operation. High power laser systems are discussed, taking into account the gasdynamic laser, the HF supersonic diffusion laser, and electric discharge lasers. Aerodynamics and high power lasers are considered, giving attention to flow effects in high-power gas lasers, aerodynamic windows and beam manipulation, and the Venus machine. Applications of high-power laser technology reported are related to laser material working, the employment of the laser in controlled fusion machines, laser isotope separation and photochemistry, and laser power transmission.

Distributed plug-and-play optimal generator and load control for power system frequency regulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhao, Changhong; Mallada, Enrique; Low, Steven H.

A distributed control scheme, which can be implemented on generators and controllable loads in a plug-and-play manner, is proposed for power system frequency regulation. The proposed scheme is based on local measurements, local computation, and neighborhood information exchanges over a communication network with an arbitrary (but connected) topology. In the event of a sudden change in generation or load, the proposed scheme can restore the nominal frequency and the reference inter-area power flows, while minimizing the total cost of control for participating generators and loads. Power network stability under the proposed control is proved with a relatively realistic model whichmore » includes nonlinear power flow and a generic (potentially nonlinear or high-order) turbine-governor model, and further with first- and second-order turbine-governor models as special cases. Finally, in simulations, the proposed control scheme shows a comparable performance to the existing automatic generation control (AGC) when implemented only on the generator side, and demonstrates better dynamic characteristics than AGC when each scheme is implemented on both generators and controllable loads. Simulation results also show robustness of the proposed scheme to communication link failure.« less

Distributed plug-and-play optimal generator and load control for power system frequency regulation

DOE PAGES

Zhao, Changhong; Mallada, Enrique; Low, Steven H.; ...

2018-03-14

A distributed control scheme, which can be implemented on generators and controllable loads in a plug-and-play manner, is proposed for power system frequency regulation. The proposed scheme is based on local measurements, local computation, and neighborhood information exchanges over a communication network with an arbitrary (but connected) topology. In the event of a sudden change in generation or load, the proposed scheme can restore the nominal frequency and the reference inter-area power flows, while minimizing the total cost of control for participating generators and loads. Power network stability under the proposed control is proved with a relatively realistic model whichmore » includes nonlinear power flow and a generic (potentially nonlinear or high-order) turbine-governor model, and further with first- and second-order turbine-governor models as special cases. Finally, in simulations, the proposed control scheme shows a comparable performance to the existing automatic generation control (AGC) when implemented only on the generator side, and demonstrates better dynamic characteristics than AGC when each scheme is implemented on both generators and controllable loads. Simulation results also show robustness of the proposed scheme to communication link failure.« less

Performance Evaluation, Emulation, and Control of Cross-Flow Hydrokinetic Turbines

NASA Astrophysics Data System (ADS)

Cavagnaro, Robert J.

Cross-flow hydrokinetic turbines are a promising option for effectively harvesting energy from fast-flowing streams or currents. This work describes the dynamics of such turbines, analyzes techniques used to scale turbine properties for prototyping, determines and demonstrates the limits of stability for cross-flow rotors, and discusses means and objectives of turbine control. Novel control strategies are under development to utilize low-speed operation (slower than at maximum power point) as a means of shedding power under rated conditions. However, operation in this regime may be unstable. An experiment designed to characterize the stability of a laboratory-scale cross-flow turbine operating near a critically low speed yields evidence that system stall (complete loss of ability to rotate) occurs due, in part, to interactions with turbulent decreases in flow speed. The turbine is capable of maintaining 'stable' operation at critical speed for short duration (typically less than 10 s), as described by exponential decay. The presence of accelerated 'bypass' flow around the rotor and decelerated 'induction' region directly upstream of the rotor, both predicted by linear momentum theory, are observed and quantified with particle image velocimetry (PIV) measurements conducted upstream of the turbine. Additionally, general agreement is seen between PIV inflow measurements and those obtained by an advection-corrected acoustic Doppler velocimeter (ADV) further upstream. Performance of a turbine at small (prototype) geometric scale may be prone to undesirable effects due to operation at low Reynolds number and in the presence of high channel blockage. Therefore, testing at larger scale, in open water is desirable. A cross-flow hydrokinetic turbine with a projected area (product of blade span and rotor diameter) of 0.7 m2 is evaluated in open-water tow trials at three inflow speeds ranging from 1.0 m/s to 2.1 m/s. Measurements of the inflow velocity, the rotor mechanical power, and electrical power output of a complete power take-off (PTO) system are utilized to determine the rotor hydrodynamic efficiency (maximum of 17%) and total system efficiency (maximum of 9%). A lab-based dynamometry method yields individual component and total PTO efficiencies, shown to have high variability and strong influence on total system efficiency. Dynamic efficiencies of PTO components can effect the overall efficiency of a turbine system, a result from field characterization. Thus, the ability to evaluate such components and their potential effects on turbine performance prior to field deployment is desirable. Before attempting control experiments with actual turbines, hardware-in-the-loop testing on controllable motor-generator sets or electromechanical emulation machines (EEMs) are explored to better understand power take-off response. The emulator control dynamic equations are presented, methods for scaling turbine parameters are developed and evaluated, and experimental results are presented from three EEMs programmed to emulate the same cross-flow turbine. Although hardware platforms and control implementations varied, results show that each EEM is successful in emulating the turbine model at different power levels, thus demonstrating the general feasibility of the approach. However, performance of motor control under torque command, current command, or speed command differed; torque methods required accurate characterization of the motors while speed methods utilized encoder feedback and more accurately tracked turbine dynamics. In a demonstration of an EEM for evaluating a hydrokinetic turbine implementation, a controller is used to track the maximum power-point of the turbine in response to turbulence. Utilizing realistic inflow conditions and control laws, the emulator dynamic speed response is shown to agree well at low frequencies with simulation but to deviate at high frequencies. The efficacy of an electromechanical emulator as an accurate representation of a fielded turbine is evaluated. A commercial horizontally-oriented cross-flow turbine is dynamically emulated on hardware to investigate control strategies and grid integration. A representative inflow time-series with a mean of 2 m/s is generated from high-resolution flow measurements of a riverine site and is used to drive emulation. Power output during emulation under similar input and loading conditions yields agreement with field measurements to within 3% at high power, near-optimal levels. Constant tip-speed ratio and constant speed proportional plus integral control schemes are compared to optimal nonlinear control and constant resistance regulation. All controllers yield similar results in terms of overall system efficiency. The emulated turbine is more responsive to turbulent inflow than the field turbine, as the model utilized to drive emulation does not account for a smoothing effect of turbulent fluctuations over the span of the fielded turbine's rotors. The turbine has a lower inertia than the demand of an isolated grid, indicating a secondary source of power with a similar frequency response is necessary if a single turbine cannot meet the entire demand. (Abstract shortened by UMI.).

33 CFR 155.780 - Emergency shutdown.

Code of Federal Regulations, 2010 CFR

2010-07-01

... the vessel to stop the flow of oil or hazardous material. (b) The means to stop the flow may be a pump control, a quick-acting, power actuated valve, or an operating procedure. If an emergency pump control is... through the stopped pump. (c) The means to stop the flow must be operable from the cargo deck, cargo...

33 CFR 155.780 - Emergency shutdown.

Code of Federal Regulations, 2013 CFR

2013-07-01

... the vessel to stop the flow of oil or hazardous material. (b) The means to stop the flow may be a pump control, a quick-acting, power actuated valve, or an operating procedure. If an emergency pump control is... through the stopped pump. (c) The means to stop the flow must be operable from the cargo deck, cargo...

33 CFR 155.780 - Emergency shutdown.

Code of Federal Regulations, 2014 CFR

2014-07-01

... the vessel to stop the flow of oil or hazardous material. (b) The means to stop the flow may be a pump control, a quick-acting, power actuated valve, or an operating procedure. If an emergency pump control is... through the stopped pump. (c) The means to stop the flow must be operable from the cargo deck, cargo...

33 CFR 155.780 - Emergency shutdown.

Code of Federal Regulations, 2011 CFR

2011-07-01

... the vessel to stop the flow of oil or hazardous material. (b) The means to stop the flow may be a pump control, a quick-acting, power actuated valve, or an operating procedure. If an emergency pump control is... through the stopped pump. (c) The means to stop the flow must be operable from the cargo deck, cargo...

33 CFR 155.780 - Emergency shutdown.

Code of Federal Regulations, 2012 CFR

2012-07-01

... the vessel to stop the flow of oil or hazardous material. (b) The means to stop the flow may be a pump control, a quick-acting, power actuated valve, or an operating procedure. If an emergency pump control is... through the stopped pump. (c) The means to stop the flow must be operable from the cargo deck, cargo...

Thermal control system for Space Station Freedom photovoltaic power module

NASA Technical Reports Server (NTRS)

Hacha, Thomas H.; Howard, Laura

1994-01-01

The electric power for Space Station Freedom (SSF) is generated by the solar arrays of the photovoltaic power modules (PVM's) and conditioned, controlled, and distributed by a power management and distribution system. The PVM's are located outboard of the alpha gimbals of SSF. A single-phase thermal control system is being developed to provide thermal control of PVM electrical equipment and energy storage batteries. This system uses ammonia as the coolant and a direct-flow deployable radiator. The description and development status of the PVM thermal control system is presented.

Thermal control system for Space Station Freedom photovoltaic power module

NASA Technical Reports Server (NTRS)

Hacha, Thomas H.; Howard, Laura S.

1992-01-01

The electric power for Space Station Freedom (SSF) is generated by the solar arrays of the photovoltaic power modules (PVM's) and conditioned, controlled, and distributed by a power management and distribution system. The PVM's are located outboard of the alpha gimbals of SSF. A single-phase thermal control system is being developed to provide thermal control of PVM electrical equipment and energy storage batteries. This system uses ammonia as the coolant and a direct-flow deployable radiator. This paper presents the description and development status of the PVM thermal control system.

Model-based reasoning for power system management using KATE and the SSM/PMAD

NASA Technical Reports Server (NTRS)

Morris, Robert A.; Gonzalez, Avelino J.; Carreira, Daniel J.; Mckenzie, F. D.; Gann, Brian

1993-01-01

The overall goal of this research effort has been the development of a software system which automates tasks related to monitoring and controlling electrical power distribution in spacecraft electrical power systems. The resulting software system is called the Intelligent Power Controller (IPC). The specific tasks performed by the IPC include continuous monitoring of the flow of power from a source to a set of loads, fast detection of anomalous behavior indicating a fault to one of the components of the distribution systems, generation of diagnosis (explanation) of anomalous behavior, isolation of faulty object from remainder of system, and maintenance of flow of power to critical loads and systems (e.g. life-support) despite fault conditions being present (recovery). The IPC system has evolved out of KATE (Knowledge-based Autonomous Test Engineer), developed at NASA-KSC. KATE consists of a set of software tools for developing and applying structure and behavior models to monitoring, diagnostic, and control applications.

Numerical Simulation of a High-Lift Configuration Embedded with High Momentum Fluidic Actuators

NASA Technical Reports Server (NTRS)

Vatsa, Veer N.; Duda, Benjamin; Fares, Ehab; Lin, John C.

2016-01-01

Numerical simulations have been performed for a vertical tail configuration with deflected rudder. The suction surface of the main element of this configuration, just upstream of the hinge line, is embedded with an array of 32 fluidic actuators that produce oscillating sweeping jets. Such oscillating jets have been found to be very effective for flow control applications in the past. In the current paper, a high-fidelity computational fluid dynamics (CFD) code known as the PowerFLOW R code is used to simulate the entire flow field associated with this configuration, including the flow inside the actuators. A fully compressible version of the PowerFLOW R code valid for high speed flows is used for the present simulations to accurately represent the transonic flow regimes encountered in the flow field due to the actuators operating at higher mass flow (momentum) rates required to mitigate reverse flow regions on a highly-deflected rudder surface. The computed results for the surface pressure and integrated forces compare favorably with measured data. In addition, numerical solutions predict the correct trends in forces with active flow control compared to the no control case. The effect of varying the rudder deflection angle on integrated forces and surface pressures is also presented.

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

NASA Technical Reports Server (NTRS)

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.

Smart grid technologies in local electric grids

NASA Astrophysics Data System (ADS)

Lezhniuk, Petro D.; Pijarski, Paweł; Buslavets, Olga A.

2017-08-01

The research is devoted to the creation of favorable conditions for the integration of renewable sources of energy into electric grids, which were designed to be supplied from centralized generation at large electric power stations. Development of distributed generation in electric grids influences the conditions of their operation - conflict of interests arises. The possibility of optimal functioning of electric grids and renewable sources of energy, when complex criterion of the optimality is balance reliability of electric energy in local electric system and minimum losses of electric energy in it. Multilevel automated system for power flows control in electric grids by means of change of distributed generation of power is developed. Optimization of power flows is performed by local systems of automatic control of small hydropower stations and, if possible, solar power plants.

Influence of blood flow occlusion on muscle oxygenation characteristics and the parameters of the power-duration relationship.

PubMed

Broxterman, R M; Ade, C J; Craig, J C; Wilcox, S L; Schlup, S J; Barstow, T J

2015-04-01

It was previously (Monod H, Scherrer J. Ergonomics 8: 329-338, 1965) postulated that blood flow occlusion during exercise would reduce critical power (CP) to 0 Watts (W), while not altering the curvature constant (W'). We empirically assessed the influence of blood flow occlusion on CP, W', and muscle oxygenation characteristics. Ten healthy men (age: 24.8 ± 2.6 yr; height: 180 ± 5 cm; weight: 84.6 ± 10.1 kg) completed four constant-power handgrip exercise tests during both control blood flow (control) and blood flow occlusion (occlusion) for the determination of the power-duration relationship. Occlusion CP (-0.7 ± 0.4 W) was significantly (P < 0.001) lower than control CP (4.1 ± 0.7 W) and significantly (P < 0.001) lower than 0 W. Occlusion W' (808 ± 155 J) was significantly (P < 0.001) different from control W' (558 ± 129 J), and all 10 subjects demonstrated an increased occlusion W' with a mean increase of ∼49%. The present findings support the aerobic nature of CP. The findings also demonstrate that the amount of work that can be performed above CP is constant for a given condition, but can vary across conditions. Moreover, this amount of work that can be performed above CP does not appear to be the determinant of W', but rather a consequence of the depletion of intramuscular energy stores and/or the accumulation of fatigue-inducing metabolites, which limit exercise tolerance and determine W'. Copyright © 2015 the American Physiological Society.

Testing of active heat sink for advanced high-power laser diodes

NASA Astrophysics Data System (ADS)

Vetrovec, John; Copeland, Drew A.; Feeler, Ryan; Junghans, Jeremy

2011-03-01

We report on the development of a novel active heat sink for high-power laser diodes offering unparalleled capacity in high-heat flux handling and temperature control. The heat sink employs convective heat transfer by a liquid metal flowing at high speed inside a miniature sealed flow loop. Liquid metal flow in the loop is maintained electromagnetically without any moving parts. Thermal conductance of the heat sink is electronically adjustable, allowing for precise control of diode temperature and the laser light wavelength. This paper presents the principles and challenges of liquid metal cooling, and data from testing at high heat flux and high heat loads.

Shock Control and Power Extraction by MHD Processes in Hypersonic Air Flow

DTIC Science & Technology

2006-11-01

green) directions. The lower curve is smoothed to remove the pulser induced oscillations. E. Modeling of Hypersonic Aerodynamic Control and Thrust ...combination of deceleration near the surface and acceleration of the outer flow at XzO. 5 , to only acceleration ( thrust ) at y=l (Fig. 19). 1 - 1 - f...7 8 9 10 M Figure 20. Thrust (F.) and lift (AL) forces, their ratio (AL/AD), and the MHD deposited power versus Mach number for MHD accelerator with X

Low power electromagnetic flowmeter providing accurate zero set

NASA Technical Reports Server (NTRS)

Fryer, T. B. (Inventor)

1971-01-01

A low power, small size electromagnetic flowmeter system is described which produces a zero output signal for zero flow. The system comprises an air core type electromagnetic flow transducer, a field current supply circuit for the transducer coils and a pre-amplifier and demodulation circuit connected to the output of the transducer. To prevent spurious signals at zero flow, separate, isolated power supplies are provided for the two circuits. The demodulator includes a pair of synchronous rectifiers which are controlled by signals from the field current supply circuit. Pulse transformer connected in front of the synchronous rectifiers provide isolation between the two circuits.

Assessment by three-dimensional power Doppler ultrasound of cerebral blood flow perfusion in fetuses with congenital heart disease.

PubMed

Zeng, S; Zhou, J; Peng, Q; Tian, L; Xu, G; Zhao, Y; Wang, T; Zhou, Q

2015-06-01

To use three-dimensional (3D) power Doppler ultrasound to investigate cerebral blood flow perfusion in fetuses with congenital heart disease (CHD). The vascularization index (VI), flow index (FI) and vascularization flow index (VFI) in the total intracranial volume and the main arterial territories (middle cerebral artery (MCA), anterior cerebral artery (ACA) and posterior cerebral artery (PCA)) were evaluated prospectively and compared in 112 fetuses with CHD and 112 normal fetuses using 3D power Doppler. Correlations between the 3D power Doppler indices and neurodevelopment scores at 12 months of age were assessed in a subset of the CHD group, and values were compared with those of controls. Compared with the controls, the VI, FI and VFI of the total intracranial volume and the three main arteries were significantly higher in fetuses with hypoplastic left heart syndrome and left-sided obstructive lesions (P < 0.001), and the 3D power Doppler values in the ACA territory were significantly higher in fetuses with transposition of the great arteries (P < 0.01). The largest proportional increase in the blood flow perfusion indices in the fetuses with CHD relative to controls was observed in the ACA territory (P < 0.05). Among 41 cases with CHD that underwent testing, the mean Psychomotor Development Index (PDI) and Mental Development Index (MDI) scores were significantly lower than in 94 of the controls that were tested (P < 0.001). Among these CHD cases, total intracranial FI was positively correlated with PDI (r = 0.342, P = 0.029) and MDI (r = 0.339, P = 0.030), and ACA-VI and ACA-VFI were positively correlated with PDI (r = 0.377 and 0.389, P = 0.015 and 0.012, respectively) but were not correlated with MDI (r = 0.243 and 0.203, P = 0.126 and 0.204, respectively). Cerebral blood flow perfusion was increased relative to controls in most fetuses with CHD and was associated with neurodevelopment scores at 12 months. Prenatal 3D power Doppler ultrasound might help to identify cases of brain vasodilatation earlier and inform parental counseling. Copyright © 2015 ISUOG. Published by John Wiley & Sons Ltd.

ARPA-E: Advancing the Electric Grid

ScienceCinema

Lemmon, John; Ruiz, Pablo; Sommerer, Tim; Aziz, Michael

2018-06-07

The electric grid was designed with the assumption that all energy generation sources would be relatively controllable, and grid operators would always be able to predict when and where those sources would be located. With the addition of renewable energy sources like wind and solar, which can be installed faster than traditional generation technologies, this is no longer the case. Furthermore, the fact that renewable energy sources are imperfectly predictable means that the grid has to adapt in real-time to changing patterns of power flow. We need a dynamic grid that is far more flexible. This video highlights three ARPA-E-funded approaches to improving the grid's flexibility: topology control software from Boston University that optimizes power flow, gas tube switches from General Electric that provide efficient power conversion, and flow batteries from Harvard University that offer grid-scale energy storage.

Design and evaluation of a microgrid for PEV charging with flexible distribution of energy sources and storage

NASA Astrophysics Data System (ADS)

Pyne, Moinak

This thesis aspires to model and control, the flow of power in a DC microgrid. Specifically, the energy sources are a photovoltaic system and the utility grid, a lead acid battery based energy storage system and twenty PEV charging stations as the loads. Theoretical principles of large scale state space modeling are applied to model the considerable number of power electronic converters needed for controlling voltage and current thresholds. The energy storage system is developed using principles of neural networks to facilitate a stable and uncomplicated model of the lead acid battery. Power flow control is structured as a hierarchical problem with multiple interactions between individual components of the microgrid. The implementation is done using fuzzy logic with scheduling the maximum use of available solar energy and compensating demand or excess power with the energy storage system, and minimizing utility grid use, while providing multiple speeds of charging the PEVs.

Implantable physiologic controller for left ventricular assist devices with telemetry capability.

PubMed

Asgari, Siavash S; Bonde, Pramod

2014-01-01

Rotary type left ventricular assist devices have mitigated the problem of durability associated with earlier pulsatile pumps and demonstrated improved survival. However, the compromise is the loss of pulsatility due to continuous flow and retained percutaneous driveline leading to increased mortality and morbidity. Lack of pulsatility is implicated in increased gastrointestinal bleeding, aortic incompetence, and diastolic hypertension. We present a novel, wirelessly powered, ultra-compact, implantable physiologic controller capable of running a left ventricular assist device in a pulsatile mode with wireless power delivery. The schematic of our system was laid out on a circuit board to wirelessly receive power and run a left ventricular assist device with required safety and backup measures. We have embedded an antenna and wireless network for telemetry. Multiple signal processing steps and controlling algorithm were incorporated. The controller was tested in in vitro and in vivo experiments. The controller drove left ventricular assist devices continuously for 2 weeks in an in vitro setup and in vivo without any failure. Our controller is more power efficient than the current Food and Drug Administration-approved left ventricular assist device controllers. When used with electrocardiography synchronization, the controller allowed on-demand customization of operation with instantaneous flow and revolutions per minute changes, resulting in a pulsatile flow with adjustable pulse pressure. Our test results prove the system to be remarkably safe, accurate, and efficient. The unique combination of wireless powering and small footprint makes this system an ideal totally implantable physiologic left ventricular assist device system. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

Voltage stability index based optimal placement of static VAR compensator and sizing using Cuckoo search algorithm

NASA Astrophysics Data System (ADS)

Venkateswara Rao, B.; Kumar, G. V. Nagesh; Chowdary, D. Deepak; Bharathi, M. Aruna; Patra, Stutee

2017-07-01

This paper furnish the new Metaheuristic algorithm called Cuckoo Search Algorithm (CSA) for solving optimal power flow (OPF) problem with minimization of real power generation cost. The CSA is found to be the most efficient algorithm for solving single objective optimal power flow problems. The CSA performance is tested on IEEE 57 bus test system with real power generation cost minimization as objective function. Static VAR Compensator (SVC) is one of the best shunt connected device in the Flexible Alternating Current Transmission System (FACTS) family. It has capable of controlling the voltage magnitudes of buses by injecting the reactive power to system. In this paper SVC is integrated in CSA based Optimal Power Flow to optimize the real power generation cost. SVC is used to improve the voltage profile of the system. CSA gives better results as compared to genetic algorithm (GA) in both without and with SVC conditions.

Optimal power flow with optimal placement TCSC device on 500 kV Java-Bali electrical power system using genetic Algorithm-Taguchi method

NASA Astrophysics Data System (ADS)

Apribowo, Chico Hermanu Brillianto; Ibrahim, Muhammad Hamka; Wicaksono, F. X. Rian

2018-02-01

The growing burden of the load and the complexity of the power system has had an impact on the need for optimization of power system operation. Optimal power flow (OPF) with optimal location placement and rating of thyristor controlled series capacitor (TCSC) is an effective solution used to determine the economic cost of operating the plant and regulate the power flow in the power system. The purpose of this study is to minimize the total cost of generation by placing the location and the optimal rating of TCSC using genetic algorithm-design of experiment techniques (GA-DOE). Simulation on Java-Bali system 500 kV with the amount of TCSC used by 5 compensator, the proposed method can reduce the generation cost by 0.89% compared to OPF without using TCSC.

Voltage droop Coordinating Control applied in UPFC and STATCOM system

NASA Astrophysics Data System (ADS)

Junhui, Huang; Zhuyi, Peng; Chengjie, Ni; Yiqing, Xu; Jiliang, Xue

2018-04-01

When UPFC, unified power flow controller is applied with other FACTS into power grid, it is possible that the voltage controlled vibrates constantly to response to a sudden reactive power turbulent in grid if the parameters of these FACTS are not coordinating reasonably. Moreover, the reactive power generated by these equipment will intertwine unexpectedly. The article proposes a method named voltage-reactive power droop control to allow the reference voltage fluctuating around the rating voltage so that the vibration is reduced and the power distribution is improved. Finally, the article cite a electric-magnetic simulation by EMTDC models of east-China power grid to prove it effective when applied to improve the response characteristics to sudden turbulence in power grid.

Numerical simulation of a powered-lift landing, tracking flow features using overset grids, and simulation of high lift devices on a fighter-lift-and-control wing

NASA Technical Reports Server (NTRS)

Chawla, Kalpana

1993-01-01

Attached as appendices to this report are documents describing work performed on the simulation of a landing powered-lift delta wing, the tracking of flow features using overset grids, and the simulation of flaps on the Wright Patterson Lab's fighter-lift-and-control (FLAC) wing. Numerical simulation of a powered-lift landing includes the computation of flow about a delta wing at four fixed heights as well as a simulated landing, in which the delta wing descends toward the ground. Comparison of computed and experimental lift coefficients indicates that the simulations capture the qualitative trends in lift-loss encountered by thrust-vectoring aircraft operating in ground effect. Power spectra of temporal variations of pressure indicate computed vortex shedding frequencies close to the jet exit are in the experimentally observed frequency range; the power spectra of pressure also provide insights into the mechanisms of lift oscillations. Also, a method for using overset grids to track dynamic flow features is described and the method is validated by tracking a moving shock and vortices shed behind a circular cylinder. Finally, Chimera gridding strategies were used to develop pressure coefficient contours for the FLAC wing for a Mach no. of 0.18 and Reynolds no. of 2.5 million.

Control of Advanced Reactor-Coupled Heat Exchanger System: Incorporation of Reactor Dynamics in System Response to Load Disturbances

DOE PAGES

Skavdahl, Isaac; Utgikar, Vivek; Christensen, Richard; ...

2016-05-24

We present an alternative control schemes for an Advanced High Temperature Reactor system consisting of a reactor, an intermediate heat exchanger, and a secondary heat exchanger (SHX) in this paper. One scheme is designed to control the cold outlet temperature of the SHX (T co) and the hot outlet temperature of the intermediate heat exchanger (T ho2) by manipulating the hot-side flow rates of the heat exchangers (F h/F h2) responding to the flow rate and temperature disturbances. The flow rate disturbances typically require a larger manipulation of the flow rates than temperature disturbances. An alternate strategy examines the controlmore » of the cold outlet temperature of the SHX (T co) only, since this temperature provides the driving force for energy production in the power conversion unit or the process application. The control can be achieved by three options: (1) flow rate manipulation; (2) reactor power manipulation; or (3) a combination of the two. The first option has a quicker response but requires a large flow rate change. The second option is the slowest but does not involve any change in the flow rates of streams. The final option appears preferable as it has an intermediate response time and requires only a minimal flow rate change.« less

Challenges in reducing the computational time of QSTS simulations for distribution system analysis.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deboever, Jeremiah; Zhang, Xiaochen; Reno, Matthew J.

The rapid increase in penetration of distributed energy resources on the electric power distribution system has created a need for more comprehensive interconnection modelling and impact analysis. Unlike conventional scenario - based studies , quasi - static time - series (QSTS) simulation s can realistically model time - dependent voltage controllers and the diversity of potential impacts that can occur at different times of year . However, to accurately model a distribution system with all its controllable devices, a yearlong simulation at 1 - second resolution is often required , which could take conventional computers a computational time of 10more » to 120 hours when an actual unbalanced distribution feeder is modeled . This computational burden is a clear l imitation to the adoption of QSTS simulation s in interconnection studies and for determining optimal control solutions for utility operations . Our ongoing research to improve the speed of QSTS simulation has revealed many unique aspects of distribution system modelling and sequential power flow analysis that make fast QSTS a very difficult problem to solve. In this report , the most relevant challenges in reducing the computational time of QSTS simulations are presented: number of power flows to solve, circuit complexity, time dependence between time steps, multiple valid power flow solutions, controllable element interactions, and extensive accurate simulation analysis.« less

Measuring Power Flow in Electric Vehicles

NASA Technical Reports Server (NTRS)

Griffin, Daniel C., Jr; Wiker, G. A.

1983-01-01

Instrument accommodates fast rise and fall times of waveforms characteristic of modern, efficient power controllers. Power meter multiplies analog signals proportional to voltage and current, and converts resulting signal to frequency. Two mechanical counters provided: one for charging, one for discharging.

Coordinated Voltage Control of Transformer Taps on account of Hierarchical Structure in Power System

NASA Astrophysics Data System (ADS)

Nakachi, Yoshiki; Kato, Satoshi; Ukai, Hiroyuki

Participation of distributed generators (DG), such as wind turbines, co-generation system etc., is natural trend from ecological point of view and will increase more and more. The outputs of these DGs mainly depend on weather condition but don't correspond to the changes of electrical load demand necessarily. On the other hand, due to the deregulation of electric power market, the power flow in power system will uncertainly vary with several power transactions. Thus, complex power flow by DGs or transactions will cause the voltage deviation. It will be difficult to sustain the voltage quality by using the conventional voltage/reactive power control in near future. In this paper, in order to avoid such a voltage deviation and to decrease the frequency of transformer tap actions, the coordinated voltage control scheme of transformer taps on account of hierarchical structure in power system is proposed. In the proposed scheme, integral of voltage deviation at each layer bus is applied to decide the timing of each transformer tap action. It is confirmed by some numerical simulations that the proposed scheme is able to respond to every conditions on voltage deviation.

A Low-Power Thermal-Based Sensor System for Low Air Flow Detection

PubMed Central

Arifuzzman, AKM; Haider, Mohammad Rafiqul; Allison, David B.

2016-01-01

Being able to rapidly detect a low air flow rate with high accuracy is essential for various applications in the automotive and biomedical industries. We have developed a thermal-based low air flow sensor with a low-power sensor readout for biomedical applications. The thermal-based air flow sensor comprises a heater and three pairs of temperature sensors that sense temperature differences due to laminar air flow. The thermal-based flow sensor was designed and simulated by using laminar flow, heat transfer in solids and fluids physics in COMSOL MultiPhysics software. The proposed sensor can detect air flow as low as 0.0064 m/sec. The readout circuit is based on a current- controlled ring oscillator in which the output frequency of the ring oscillator is proportional to the temperature differences of the sensors. The entire readout circuit was designed and simulated by using a 130-nm standard CMOS process. The sensor circuit features a small area and low-power consumption of about 22.6 µW with an 800 mV power supply. In the simulation, the output frequency of the ring oscillator and the change in thermistor resistance showed a high linearity with an R2 value of 0.9987. The low-power dissipation, high linearity and small dimensions of the proposed flow sensor and circuit make the system highly suitable for biomedical applications. PMID:28435186

Performance of a High-Fidelity 4kW-Class Engineering Model PPU and Integration with HiVHAc System

NASA Technical Reports Server (NTRS)

Pinero, Luis R.; Kamhawi, Hani; Shilo, Vladislav

2016-01-01

The High Voltage Hall Accelerator (HiVHAc) propulsion system consists of a thruster,power processing unit (PPU), and propellant feed system. An engineering model PPU was developed by Colorado Power Electronics, Inc. funded by NASA's Small Business Innovative Research Program. This PPU uses an innovative 3-phase resonant converter to deliver 4 kW of discharge power over a wide range of input and output voltage conditions.The PPU includes a digital control interface unit that automatically controls the PPU and a xenon flow control module (XFCM). It interfaces with a control computer to receive high level commands and relay telemetry through a MIL-STD-1553B interface. The EM PPU was thoroughly tested at GRC for functionality and performance at temperature extremes and demonstrated total efficiencies a high as 95 percent. It was integrated with the HiVHAc thruster and the XFCM to demonstrate closed-loop control of discharge current with anode flow. Initiation of the main discharge and power throttling were also successfully demonstrated and discharge oscillations were characterized.

Performance of a High-Fidelity 4kW-Class Engineering Model PPU and Integration with HiVHAc System

NASA Technical Reports Server (NTRS)

Pinero, Luis R.; Kamhawi, Hani; Shilo, Vlad

2016-01-01

The High Voltage Hall Accelerator (HiVHAc) propulsion system consists of a thruster, power processing unit (PPU), and propellant feed system. An engineering model PPU was developed by Colorado Power Electronics, Inc. funded by NASA's Small Business Innovative Research Program. This PPU uses an innovative 3-phase resonant converter to deliver 4 kW of discharge power over a wide range of input and output voltage conditions. The PPU includes a digital control interface unit that automatically controls the PPU and a xenon flow control module (XFCM). It interfaces with a control computer to receive highlevel commands and relay telemetry through a MIL-STD-1553B interface. The EM PPU was thoroughly tested at GRC for functionality and performance at temperature limits and demonstrated total efficiencies a high as 95 percent. Integrated testing of the unit was performed with the HiVHAc thruster and the XFCM to demonstrate closed-loop control of discharge current with anode flow. Initiation of the main discharge and power throttling were also successfully demonstrated and discharge oscillations were characterized.

Experimental validation of tonal noise control from subsonic axial fans using flow control obstructions

NASA Astrophysics Data System (ADS)

Gérard, Anthony; Berry, Alain; Masson, Patrice; Gervais, Yves

2009-03-01

This paper presents the acoustic performance of a novel approach for the passive adaptive control of tonal noise radiated from subsonic fans. Tonal noise originates from non-uniform flow that causes circumferentially varying blade forces and gives rise to a considerably larger radiated dipolar sound at the blade passage frequency (BPF) and its harmonics compared to the tonal noise generated by a uniform flow. The approach presented in this paper uses obstructions in the flow to destructively interfere with the primary tonal noise arising from various flow conditions. The acoustic radiation of the obstructions is first demonstrated experimentally. Indirect on-axis acoustic measurements are used to validate the analytical prediction of the circumferential spectrum of the blade unsteady lift and related indicators generated by the trapezoidal and sinusoidal obstructions presented in Ref. [A. Gérard, A. Berry, P. Masson, Y. Gervais, Modelling of tonal noise control from subsonic axial fans using flow control obstructions, Journal of Sound and Vibration (2008), this issue, doi: 10.1016/j.jsv.2008.09.027.] and also by cylindrical obstructions used in the literature. The directivity and sound power attenuation are then given in free field for the control of the BPF tone generated by rotor/outlet guide vane (OGV) interaction and the control of an amplified BPF tone generated by the rotor/OGV interaction with an added triangular obstruction between two outlet guide vanes to enhance the primary non-uniform flow. Global control was demonstrated in free field, attenuation up to 8.4 dB of the acoustic power at BPF has been measured. Finally, the aerodynamic performances of the automotive fan used in this study are almost not affected by the presence of the control obstruction.

New power sharing control for inverter-dominated microgrid based on impedance match concept.

PubMed

Gu, Herong; Wang, Deyu; Shen, Hong; Zhao, Wei; Guo, Xiaoqiang

2013-01-01

Power flow control is one of the most important issues for operating the inverter-dominated autonomous microgrid. A technical challenge is how to achieve the accurate active/reactive power sharing of inverters. P-F and Q-V droop control schemes have been widely used for power sharing in the past decades. But they suffer from the poor power sharing in the presence of unequal line impedance. In order to solve the problem, a comprehensive analysis of the power droop control is presented, and a new droop control based on the impedance match concept is proposed in this paper. In addition, the design guidelines of control coefficients and virtual impedance are provided. Finally, the performance evaluation is carried out, and the evaluation results verify the effectiveness of the proposed method.

A Study of the Time Dependence in Fracture Processes Relating to Service Life Prediction of Adhesive Joints and Advanced Composites.

DTIC Science & Technology

1981-04-30

fluid temperature should exceed 145°F. The flow control module contains all the hydraulic circuit elements necessary for both the pressure line to and...are contained in three basic modules : 1) the hydraulic power supply, 2) a flow control module containing valving, accumulators and filters, and 3) the...hydraulic transient overpressures, is located in the flow control module , as are the high and low pressure filters. The load frame (MTS Systems Corp

X-29 vortex flow control tests

NASA Technical Reports Server (NTRS)

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.

Digital stroboscopic holographic interferometry for power flow measurements in acoustically driven membranes

NASA Astrophysics Data System (ADS)

Keustermans, William; Pires, Felipe; De Greef, Daniël; Vanlanduit, Steve J. A.; Dirckx, Joris J. J.

2016-06-01

Despite the importance of the eardrum and the ossicles in the hearing chain, it remains an open question how acoustical energy is transmitted between them. Identifying the transmission path at different frequencies could lead to valuable information for the domain of middle ear surgery. In this work a setup for stroboscopic holography is combined with an algorithm for power flow calculations. With our method we were able to accurately locate the power sources and sinks in a membrane. The setup enabled us to make amplitude maps of the out-of-plane displacement of a vibrating rubber membrane at subsequent instances of time within the vibration period. From these, the amplitude maps of the moments of force and velocities are calculated. The magnitude and phase maps are extracted from this amplitude data, and form the input for the power flow calculations. We present the algorithm used for the measurements and for the power flow calculations. Finite element models of a circular plate with a local energy source and sink allowed us to test and optimize this algorithm in a controlled way and without the present of noise, but will not be discussed below. At the setup an earphone was connected with a thin tube which was placed very close to the membrane so that sound impinges locally on the membrane, hereby acting as a local energy source. The energy sink was a little piece of foam carefully placed against the membrane. The laser pulses are fired at selected instants within the vibration period using a 30 mW HeNe continuous wave laser (red light, 632.8 nm) in combination with an acousto-optic modulator. A function generator controls the phase of these illumination pulses and the holograms are recorded using a CCD camera. We present the magnitude and phase maps as well as the power flow measurements on the rubber membrane. Calculation of the divergence of this power flow map provides a simple and fast way of identifying and locating an energy source or sink. In conclusion possible future improvements to the setup and the power flow algorithm are discussed.

Development of Localized Arc Filament RF Plasma Actuators for High-Speed and High Reynolds Number Flow Control

DTIC Science & Technology

2010-01-01

high-speed flows is problematic due to their low forcing frequency (for mechanical actuators) and low forcing amplitude (for piezo actuators...very low fraction of DC power is coupled to the actuators (5-10%), with the rest of the power dissipated in massive ballast resistors acting as heat... resistors . The use of high-power resistors also significantly increases the weight and size of the plasma generator and makes scaling to a large number of

Bio-medical flow sensor. [intrvenous procedures

NASA Technical Reports Server (NTRS)

Winkler, H. E. (Inventor)

1981-01-01

A bio-medical flow sensor including a packageable unit of a bottle, tubing and hypodermic needle which can be pre-sterilized and is disposable. The tubing has spaced apart tubular metal segments. The temperature of the metal segments and fluid flow therein is sensed by thermistors and at a downstream location heat is input by a resistor to the metal segment by a control electronics. The fluids flow and the electrical power required for the resisto to maintain a constant temperature differential between the tubular metal segments is a measurable function of fluid flow through the tubing. The differential temperature measurement is made in a control electronics and also can be used to control a flow control valve or pump on the tubing to maintain a constant flow in the tubing and to shut off the tubing when air is present in the tubing.

Dynamic ADMM for Real-Time Optimal Power Flow: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall-Anese, Emiliano; Zhang, Yijian; Hong, Mingyi

This paper considers distribution networks featuring distributed energy resources (DERs), and develops a dynamic optimization method to maximize given operational objectives in real time while adhering to relevant network constraints. The design of the dynamic algorithm is based on suitable linearizations of the AC power flow equations, and it leverages the so-called alternating direction method of multipliers (ADMM). The steps of the ADMM, however, are suitably modified to accommodate appropriate measurements from the distribution network and the DERs. With the aid of these measurements, the resultant algorithm can enforce given operational constraints in spite of inaccuracies in the representation ofmore » the AC power flows, and it avoids ubiquitous metering to gather the state of non-controllable resources. Optimality and convergence of the propose algorithm are established in terms of tracking of the solution of a convex surrogate of the AC optimal power flow problem.« less

Novel Active Combustion Control Valve

NASA Technical Reports Server (NTRS)

Caspermeyer, Matt

2014-01-01

This project presents an innovative solution for active combustion control. Relative to the state of the art, this concept provides frequency modulation (greater than 1,000 Hz) in combination with high-amplitude modulation (in excess of 30 percent flow) and can be adapted to a large range of fuel injector sizes. Existing valves often have low flow modulation strength. To achieve higher flow modulation requires excessively large valves or too much electrical power to be practical. This active combustion control valve (ACCV) has high-frequency and -amplitude modulation, consumes low electrical power, is closely coupled with the fuel injector for modulation strength, and is practical in size and weight. By mitigating combustion instabilities at higher frequencies than have been previously achieved (approximately 1,000 Hz), this new technology enables gas turbines to run at operating points that produce lower emissions and higher performance.

Linear Power-Flow Models in Multiphase Distribution Networks: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bernstein, Andrey; Dall'Anese, Emiliano

This paper considers multiphase unbalanced distribution systems and develops approximate power-flow models where bus-voltages, line-currents, and powers at the point of common coupling are linearly related to the nodal net power injections. The linearization approach is grounded on a fixed-point interpretation of the AC power-flow equations, and it is applicable to distribution systems featuring (i) wye connections; (ii) ungrounded delta connections; (iii) a combination of wye-connected and delta-connected sources/loads; and, (iv) a combination of line-to-line and line-to-grounded-neutral devices at the secondary of distribution transformers. The proposed linear models can facilitate the development of computationally-affordable optimization and control applications -- frommore » advanced distribution management systems settings to online and distributed optimization routines. Performance of the proposed models is evaluated on different test feeders.« less

How to Integrate Variable Power Source into a Power Grid

NASA Astrophysics Data System (ADS)

Asano, Hiroshi

This paper discusses how to integrate variable power source such as wind power and photovoltaic generation into a power grid. The intermittent renewable generation is expected to penetrate for less carbon intensive power supply system, but it causes voltage control problem in the distribution system, and supply-demand imbalance problem in a whole power system. Cooperative control of customers' energy storage equipment such as water heater with storage tank for reducing inverse power flow from the roof-top PV system, the operation technique using a battery system and the solar radiation forecast for stabilizing output of variable generation, smart charging of plug-in hybrid electric vehicles for load frequency control (LFC), and other methods to integrate variable power source with improving social benefits are surveyed.

Drag reduction and thrust generation by tangential surface motion in flow past a cylinder

NASA Astrophysics Data System (ADS)

Mao, Xuerui; Pearson, Emily

2018-03-01

Sensitivity of drag to tangential surface motion is calculated in flow past a circular cylinder in both two- and three-dimensional conditions at Reynolds number Re ≤ 1000 . The magnitude of the sensitivity maximises in the region slightly upstream of the separation points where the contour lines of spanwise vorticity are normal to the cylinder surface. A control to reduce drag can be obtained by (negatively) scaling the sensitivity. The high correlation of sensitivities of controlled and uncontrolled flow indicates that the scaled sensitivity is a good approximation of the nonlinear optimal control. It is validated through direct numerical simulations that the linear range of the steady control is much higher than the unsteady control, which synchronises the vortex shedding and induces lock-in effects. The steady control injects angular momentum into the separating boundary layer, stabilises the flow and increases the base pressure significantly. At Re=100 , when the maximum tangential motion reaches 50% of the free-stream velocity, the vortex shedding, boundary-layer separation and recirculation bubbles are eliminated and 32% of the drag is reduced. When the maximum tangential motion reaches 2.5 times of the free-stream velocity, thrust is generated and the power savings ratio, defined as the ratio of the reduced drag power to the control input power, reaches 19.6. The mechanism of drag reduction is attributed to the change of the radial gradient of spanwise vorticity (partial r \\hat{ζ } ) and the subsequent accelerated pressure recovery from the uncontrolled separation points to the rear stagnation point.

7 CFR 1710.252 - Construction work plans-power supply borrowers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... operating systems of supporting power pools and to connect with adjacent power suppliers; (4) Improvements..., new substations and substation improvements and replacements, and Systems Control and Data Acquisition... include studies of load flows, voltage regulation, and stability characteristics to demonstrate system...

7 CFR 1710.252 - Construction work plans-power supply borrowers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... operating systems of supporting power pools and to connect with adjacent power suppliers; (4) Improvements..., new substations and substation improvements and replacements, and Systems Control and Data Acquisition... include studies of load flows, voltage regulation, and stability characteristics to demonstrate system...

7 CFR 1710.252 - Construction work plans-power supply borrowers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... operating systems of supporting power pools and to connect with adjacent power suppliers; (4) Improvements..., new substations and substation improvements and replacements, and Systems Control and Data Acquisition... include studies of load flows, voltage regulation, and stability characteristics to demonstrate system...

7 CFR 1710.252 - Construction work plans-power supply borrowers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... operating systems of supporting power pools and to connect with adjacent power suppliers; (4) Improvements..., new substations and substation improvements and replacements, and Systems Control and Data Acquisition... include studies of load flows, voltage regulation, and stability characteristics to demonstrate system...

7 CFR 1710.252 - Construction work plans-power supply borrowers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... operating systems of supporting power pools and to connect with adjacent power suppliers; (4) Improvements..., new substations and substation improvements and replacements, and Systems Control and Data Acquisition... include studies of load flows, voltage regulation, and stability characteristics to demonstrate system...

Convective flow reversal in self-powered enzyme micropumps.

PubMed

Ortiz-Rivera, Isamar; Shum, Henry; Agrawal, Arjun; Sen, Ayusman; Balazs, Anna C

2016-03-08

Surface-bound enzymes can act as pumps that drive large-scale fluid flows in the presence of their substrates or promoters. Thus, enzymatic catalysis can be harnessed for “on demand” pumping in nano- and microfluidic devices powered by an intrinsic energy source. The mechanisms controlling the pumping have not, however, been completely elucidated. Herein, we combine theory and experiments to demonstrate a previously unreported spatiotemporal variation in pumping behavior in urease-based pumps and uncover the mechanisms behind these dynamics. We developed a theoretical model for the transduction of chemical energy into mechanical fluid flow in these systems, capturing buoyancy effects due to the solution containing nonuniform concentrations of substrate and product. We find that the qualitative features of the flow depend on the ratios of diffusivities δ=D(P)/D(S) and expansion coefficients β=β(P)/β(S) of the reaction substrate (S) and product (P). If δ>1 and δ>β (or if δ<1 and δ<β ), an unexpected phenomenon arises: the flow direction reverses with time and distance from the pump. Our experimental results are in qualitative agreement with the model and show that both the speed and direction of fluid pumping (i) depend on the enzyme activity and coverage, (ii) vary with the distance from the pump, and (iii) evolve with time. These findings permit the rational design of enzymatic pumps that accurately control the direction and speed of fluid flow without external power sources, enabling effective, self-powered fluidic devices.

Convective flow reversal in self-powered enzyme micropumps

PubMed Central

Ortiz-Rivera, Isamar; Shum, Henry; Agrawal, Arjun; Sen, Ayusman; Balazs, Anna C.

2016-01-01

Surface-bound enzymes can act as pumps that drive large-scale fluid flows in the presence of their substrates or promoters. Thus, enzymatic catalysis can be harnessed for “on demand” pumping in nano- and microfluidic devices powered by an intrinsic energy source. The mechanisms controlling the pumping have not, however, been completely elucidated. Herein, we combine theory and experiments to demonstrate a previously unreported spatiotemporal variation in pumping behavior in urease-based pumps and uncover the mechanisms behind these dynamics. We developed a theoretical model for the transduction of chemical energy into mechanical fluid flow in these systems, capturing buoyancy effects due to the solution containing nonuniform concentrations of substrate and product. We find that the qualitative features of the flow depend on the ratios of diffusivities δ=DP/DS and expansion coefficients β=βP/βS of the reaction substrate (S) and product (P). If δ>1 and δ>β (or if δ<1 and δ<β), an unexpected phenomenon arises: the flow direction reverses with time and distance from the pump. Our experimental results are in qualitative agreement with the model and show that both the speed and direction of fluid pumping (i) depend on the enzyme activity and coverage, (ii) vary with the distance from the pump, and (iii) evolve with time. These findings permit the rational design of enzymatic pumps that accurately control the direction and speed of fluid flow without external power sources, enabling effective, self-powered fluidic devices. PMID:26903618

Development of an inflow controlled environmental flow regime for a Norwegian river

NASA Astrophysics Data System (ADS)

Alfredsen, Knut; Harby, Atle; Linnansaari, Tommi; Ugedal, Ola

2010-05-01

For most regulated rivers in Norway the common environmental flow regime is static and shows very little variation over the year. Recent research indicate that flow regimes that follow the natural inflow variation can meet the ecological and social demands for water in a better way. The implementation of a variable environmental flow regime provides many challenges both related to defining flow for various species and user groups in the river, but also due to practical implementation, legislation and control. A inflow controlled flow regime is developed for a Norwegian river regulated for hydro power as a pilot study. The regime should meet ecological demands from Atlantic salmon and brown trout, recreational use of water and visual impression of the river. This should be achieved preferably without altering the energy production in the hydro power system. The flow regime is developed for wet, dry and normal discharge conditions based on unregulated inflow to the catchment. The development of the seasonal flow requirements for various targets identified is done using a modification of the Building Block Method. Several options are tested regarding the integration of the flow regime into the operational strategy of the hydropower plant, both using real time prognosis of inflow and combinations with historical data. An important topic in selecting the release strategy is how it meets current Norwegian legislation and how well future documentation and environmental control can be carried out. An evaluation protocol is also proposed for the flow regime to test if the ecological targets are met.

Balancing the Power-to-Load Ratio for a Novel Variable Geometry Wave Energy Converter with Nonideal Power Take-Off in Regular Waves: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tom, Nathan M; Yu, Yi-Hsiang; Wright, Alan D

This work attempts to balance power absorption against structural loading for a novel variable geometry wave energy converter. The variable geometry consists of four identical flaps that will be opened in ascending order starting with the flap closest to the seafloor and moving to the free surface. The influence of a pitch motion constraint on power absorption when utilizing a nonideal power take-off (PTO) is examined and found to reduce the losses associated with bidirectional energy flow. The power-to-load ratio is evaluated using pseudo-spectral control to determine the optimum PTO torque based on a multiterm objective function. The pseudo-spectral optimalmore » control problem is extended to include load metrics in the objective function, which may now consist of competing terms. Separate penalty weights are attached to the surge-foundation force and PTO control torque to tune the optimizer performance to emphasize either power absorption or load shedding. PTO efficiency is not included in the objective function, but the penalty weights are utilized to limit the force and torque amplitudes, thereby reducing losses associated with bidirectional energy flow. Results from pseudo-spectral control demonstrate that shedding a portion of the available wave energy can provide greater reductions in structural loads and reactive power.« less

Design of an Input-Parallel Output-Parallel LLC Resonant DC-DC Converter System for DC Microgrids

NASA Astrophysics Data System (ADS)

Juan, Y. L.; Chen, T. R.; Chang, H. M.; Wei, S. E.

2017-11-01

Compared with the centralized power system, the distributed modularized power system is composed of several power modules with lower power capacity to provide a totally enough power capacity for the load demand. Therefore, the current stress of the power components in each module can then be reduced, and the flexibility of system setup is also enhanced. However, the parallel-connected power modules in the conventional system are usually controlled to equally share the power flow which would result in lower efficiency in low loading condition. In this study, a modular power conversion system for DC micro grid is developed with 48 V dc low voltage input and 380 V dc high voltage output. However, in the developed system control strategy, the numbers of power modules enabled to share the power flow is decided according to the output power at lower load demand. Finally, three 350 W power modules are constructed and parallel-connected to setup a modular power conversion system. From the experimental results, compared with the conventional system, the efficiency of the developed power system in the light loading condition is greatly improved. The modularized design of the power system can also decrease the power loss ratio to the system capacity.

Hamiltonian methods of modeling and control of AC microgrids with spinning machines and inverters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matthews, Ronald C.; Weaver, Wayne W.; Robinett, Rush D.

This study presents a novel approach to the modeling and control of AC microgrids that contain spinning machines, power electronic inverters and energy storage devices. The inverters in the system can adjust their frequencies and power angles very quickly, so the modeling focuses on establishing a common reference frequency and angle in the microgrid based on the spinning machines. From this dynamic model, nonlinear Hamiltonian surface shaping and power flow control method is applied and shown to stabilize. From this approach the energy flow in the system is used to show the energy storage device requirements and limitations for themore » system. This paper first describes the model for a single bus AC microgrid with a Hamiltonian control, then extends this model and control to a more general class of multiple bus AC microgrids. Finally, simulation results demonstrate the efficacy of the approach in stabilizing and optimization of the microgrid.« less

Hamiltonian methods of modeling and control of AC microgrids with spinning machines and inverters

DOE PAGES

Matthews, Ronald C.; Weaver, Wayne W.; Robinett, Rush D.; ...

2017-12-22

This study presents a novel approach to the modeling and control of AC microgrids that contain spinning machines, power electronic inverters and energy storage devices. The inverters in the system can adjust their frequencies and power angles very quickly, so the modeling focuses on establishing a common reference frequency and angle in the microgrid based on the spinning machines. From this dynamic model, nonlinear Hamiltonian surface shaping and power flow control method is applied and shown to stabilize. From this approach the energy flow in the system is used to show the energy storage device requirements and limitations for themore » system. This paper first describes the model for a single bus AC microgrid with a Hamiltonian control, then extends this model and control to a more general class of multiple bus AC microgrids. Finally, simulation results demonstrate the efficacy of the approach in stabilizing and optimization of the microgrid.« less

New Power Sharing Control for Inverter-Dominated Microgrid Based on Impedance Match Concept

PubMed Central

Gu, Herong; Wang, Deyu; Shen, Hong; Zhao, Wei; Guo, Xiaoqiang

2013-01-01

Power flow control is one of the most important issues for operating the inverter-dominated autonomous microgrid. A technical challenge is how to achieve the accurate active/reactive power sharing of inverters. P-F and Q-V droop control schemes have been widely used for power sharing in the past decades. But they suffer from the poor power sharing in the presence of unequal line impedance. In order to solve the problem, a comprehensive analysis of the power droop control is presented, and a new droop control based on the impedance match concept is proposed in this paper. In addition, the design guidelines of control coefficients and virtual impedance are provided. Finally, the performance evaluation is carried out, and the evaluation results verify the effectiveness of the proposed method. PMID:24453910

High efficiency stoichiometric internal combustion engine system

DOEpatents

Winsor, Richard Edward; Chase, Scott Allen

2009-06-02

A power system including a stoichiometric compression ignition engine in which a roots blower is positioned in the air intake for the engine to control air flow. Air flow is decreased during part power conditions to maintain the air-fuel ratio in the combustion chamber of the engine at stoichiometric, thus enabling the use of inexpensive three-way catalyst to reduce oxides of nitrogen. The roots blower is connected to a motor generator so that when air flow is reduced, electrical energy is stored which is made available either to the roots blower to temporarily increase air flow or to the system electrical load and thus recapture energy that would otherwise be lost in reducing air flow.

Concept Design Report for a Low draft Stabilized - High Speed Connector (LDS-HSC) Vessel for the ONR High Speed Sea Lift (HSSL) Program

DTIC Science & Technology

2007-04-30

control of cushion air flow and, hence, control of cushion pressure fore and aft of the divider that provides significant dynamic control of ship pitch...fore and aft of the divider that provides significant dynamic control of ship pitch and heave in a seaway. All these modes of operation were tested by...Installed Power, SHP 402,306 Integrated Power System (IPS) featuring: * (6) 50 MW Rolls-Royce MT50 based Gensets Power Plant * Associated Conversion and

Aircraft energy efficiency laminar flow control glove flight conceptual design study

NASA Technical Reports Server (NTRS)

Wright, A. S.

1979-01-01

A laminar flow control glove applied to the wing of a short to medium range jet transport with aft mounted engines was designed. A slotted aluminum glove concept and a woven stainless steel mesh porous glove concept suction surfaces were studied. The laminar flow control glove and a dummy glove with a modified supercritical airfoil, ducting, modified wing leading and trailing edges, modified flaps, and an LFC trim tab were applied to the wing after slot spacing suction parameters, and compression power were determined. The results show that a laminar flow control glove can be applied to the wing of a jet transport with an appropriate suction system installed.

Evaluation of pressure and thermal data from a wind tunnel test of a large-scale, powered, STOL fighter model

NASA Technical Reports Server (NTRS)

Howell, G. A.; Crosthwait, E. L.; Witte, M. C.

1981-01-01

A STOL fighter model employing the vectored-engine-over wing concept was tested at low speeds in the NASA/Ames 40 by 80-foot wind tunnel. The model, approximately 0.75 scale of an operational fighter, was powered by two General Electric J-97 turbojet engines. Limited pressure and thermal instrumentation were provided to measure power effects (chordwise and spanwise blowing) and control-surface-deflection effects. An indepth study of the pressure and temperature data revealed many flow field features - the foremost being wing and canard leading-edge vortices. These vortices delineated regions of attached and separated flow, and their movements were often keys to an understanding of flow field changes caused by power and control-surface variations. Chordwise blowing increased wing lift and caused a modest aft shift in the center of pressure. The induced effects of chordwise blowing extended forward to the canard and significantly increased the canard lift when the surface was stalled. Spanwise blowing effectively enhanced the wing leading-edge vortex, thereby increasing lift and causing a forward shift in the center of pressure.

Weakly Ionized Plasmas in Hypersonics: Fundamental Kinetics and Flight Applications

NASA Astrophysics Data System (ADS)

Macheret, Sergey

2005-05-01

The paper reviews some of the recent studies of applications of weakly ionized plasmas to supersonic/hypersonic flight. Plasmas can be used simply as means of delivering energy (heating) to the flow, and also for electromagnetic flow control and magnetohydrodynamic (MHD) power generation. Plasma and MHD control can be especially effective in transient off-design flight regimes. In cold air flow, nonequilibrium plasmas must be created, and the ionization power budget determines design, performance envelope, and the very practicality of plasma/MHD devices. The minimum power budget is provided by electron beams and repetitive high-voltage nanosecond pulses, and the paper describes theoretical and computational modeling of plasmas created by the beams and repetitive pulses. The models include coupled equations for non-local and unsteady electron energy distribution function (modeled in forward-back approximation), plasma kinetics, and electric field. Recent experimental studies at Princeton University have successfully demonstrated stable diffuse plasmas sustained by repetitive nanosecond pulses in supersonic air flow, and for the first time have demonstrated the existence of MHD effects in such plasmas. Cold-air hypersonic MHD devices are shown to permit optimization of scramjet inlets at Mach numbers higher than the design value, while operating in self-powered regime. Plasma energy addition upstream of the inlet throat can increase the thrust by capturing more air (Virtual Cowl), or it can reduce the flow Mach number and thus eliminate the need for an isolator duct. In the latter two cases, the power that needs to be supplied to the plasma would be generated by an MHD generator downstream of the combustor, thus forming the "reverse energy bypass" scheme. MHD power generation on board reentry vehicles is also discussed.

A robust approach to chance constrained optimal power flow with renewable generation

DOE PAGES

Lubin, Miles; Dvorkin, Yury; Backhaus, Scott N.

2016-09-01

Optimal Power Flow (OPF) dispatches controllable generation at minimum cost subject to operational constraints on generation and transmission assets. The uncertainty and variability of intermittent renewable generation is challenging current deterministic OPF approaches. Recent formulations of OPF use chance constraints to limit the risk from renewable generation uncertainty, however, these new approaches typically assume the probability distributions which characterize the uncertainty and variability are known exactly. We formulate a robust chance constrained (RCC) OPF that accounts for uncertainty in the parameters of these probability distributions by allowing them to be within an uncertainty set. The RCC OPF is solved usingmore » a cutting-plane algorithm that scales to large power systems. We demonstrate the RRC OPF on a modified model of the Bonneville Power Administration network, which includes 2209 buses and 176 controllable generators. In conclusion, deterministic, chance constrained (CC), and RCC OPF formulations are compared using several metrics including cost of generation, area control error, ramping of controllable generators, and occurrence of transmission line overloads as well as the respective computational performance.« less

Optimal Scheduling Method of Controllable Loads in DC Smart Apartment Building

NASA Astrophysics Data System (ADS)

Shimoji, Tsubasa; Tahara, Hayato; Matayoshi, Hidehito; Yona, Atsushi; Senjyu, Tomonobu

2015-12-01

From the perspective of global warming suppression and the depletion of energy resources, renewable energies, such as the solar collector (SC) and photovoltaic generation (PV), have been gaining attention in worldwide. Houses or buildings with PV and heat pumps (HPs) are recently being used in residential areas widely due to the time of use (TOU) electricity pricing scheme which is essentially inexpensive during middle-night and expensive during day-time. If fixed batteries and electric vehicles (EVs) can be introduced in the premises, the electricity cost would be even more reduced. While, if the occupants arbitrarily use these controllable loads respectively, power demand in residential buildings may fluctuate in the future. Thus, an optimal operation of controllable loads such as HPs, batteries and EV should be scheduled in the buildings in order to prevent power flow from fluctuating rapidly. This paper proposes an optimal scheduling method of controllable loads, and the purpose is not only the minimization of electricity cost for the consumers, but also suppression of fluctuation of power flow on the power supply side. Furthermore, a novel electricity pricing scheme is also suggested in this paper.

Network-Cognizant Voltage Droop Control for Distribution Grids

DOE PAGES

Baker, Kyri; Bernstein, Andrey; Dall'Anese, Emiliano; ...

2017-08-07

Our paper examines distribution systems with a high integration of distributed energy resources (DERs) and addresses the design of local control methods for real-time voltage regulation. Particularly, the paper focuses on proportional control strategies where the active and reactive output-powers of DERs are adjusted in response to (and proportionally to) local changes in voltage levels. The design of the voltage-active power and voltage-reactive power characteristics leverages suitable linear approximation of the AC power-flow equations and is network-cognizant; that is, the coefficients of the controllers embed information on the location of the DERs and forecasted non-controllable loads/injections and, consequently, on themore » effect of DER power adjustments on the overall voltage profile. We pursued a robust approach to cope with uncertainty in the forecasted non-controllable loads/power injections. Stability of the proposed local controllers is analytically assessed and numerically corroborated.« less

Network-Cognizant Voltage Droop Control for Distribution Grids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baker, Kyri; Bernstein, Andrey; Dall'Anese, Emiliano

Our paper examines distribution systems with a high integration of distributed energy resources (DERs) and addresses the design of local control methods for real-time voltage regulation. Particularly, the paper focuses on proportional control strategies where the active and reactive output-powers of DERs are adjusted in response to (and proportionally to) local changes in voltage levels. The design of the voltage-active power and voltage-reactive power characteristics leverages suitable linear approximation of the AC power-flow equations and is network-cognizant; that is, the coefficients of the controllers embed information on the location of the DERs and forecasted non-controllable loads/injections and, consequently, on themore » effect of DER power adjustments on the overall voltage profile. We pursued a robust approach to cope with uncertainty in the forecasted non-controllable loads/power injections. Stability of the proposed local controllers is analytically assessed and numerically corroborated.« less

A study on the impact of high penetration distributed generation inverters on grid operation and stability

NASA Astrophysics Data System (ADS)

Gu, Fei; Brouwer, Jack; Samuelsen, Scott

2013-09-01

Recent advances in inverter technology have enabled ancillary services such as volt/VAR regulation, SCADA communications, and active power filtering. Smart inverters can not only provide real power, but can be controlled to use excess capacity to provide reactive power compensation, power flow control, and active power filtering without supplementary inverter hardware. A transient level inverter model based on the Solectria 7700 inverter is developed and used to assess these control strategies using field data from an existing branch circuit containing two Amonix 68kW CPV-7700 systems installed at the University of California, Irvine.

An Novel Continuation Power Flow Method Based on Line Voltage Stability Index

NASA Astrophysics Data System (ADS)

Zhou, Jianfang; He, Yuqing; He, Hongbin; Jiang, Zhuohan

2018-01-01

An novel continuation power flow method based on line voltage stability index is proposed in this paper. Line voltage stability index is used to determine the selection of parameterized lines, and constantly updated with the change of load parameterized lines. The calculation stages of the continuation power flow decided by the angle changes of the prediction of development trend equation direction vector are proposed in this paper. And, an adaptive step length control strategy is used to calculate the next prediction direction and value according to different calculation stages. The proposed method is applied clear physical concept, and the high computing speed, also considering the local characteristics of voltage instability which can reflect the weak nodes and weak area in a power system. Due to more fully to calculate the PV curves, the proposed method has certain advantages on analysing the voltage stability margin to large-scale power grid.

Active Combustion Control for Aircraft Gas-Turbine Engines-Experimental Results for an Advanced, Low-Emissions Combustor Prototype

NASA Technical Reports Server (NTRS)

DeLaat, John C.; Kopasakis, George; Saus, Joseph R.; Chang, Clarence T.; Wey, Changlie

2012-01-01

Lean combustion concepts for aircraft engine combustors are prone to combustion instabilities. Mitigation of instabilities is an enabling technology for these low-emissions combustors. NASA Glenn Research Center s prior activity has demonstrated active control to suppress a high-frequency combustion instability in a combustor rig designed to emulate an actual aircraft engine instability experience with a conventional, rich-front-end combustor. The current effort is developing further understanding of the problem specifically as applied to future lean-burning, very low-emissions combustors. A prototype advanced, low-emissions aircraft engine combustor with a combustion instability has been identified and previous work has characterized the dynamic behavior of that combustor prototype. The combustor exhibits thermoacoustic instabilities that are related to increasing fuel flow and that potentially prevent full-power operation. A simplified, non-linear oscillator model and a more physics-based sectored 1-D dynamic model have been developed to capture the combustor prototype s instability behavior. Utilizing these models, the NASA Adaptive Sliding Phasor Average Control (ASPAC) instability control method has been updated for the low-emissions combustor prototype. Active combustion instability suppression using the ASPAC control method has been demonstrated experimentally with this combustor prototype in a NASA combustion test cell operating at engine pressures, temperatures, and flows. A high-frequency fuel valve was utilized to perturb the combustor fuel flow. Successful instability suppression was shown using a dynamic pressure sensor in the combustor for controller feedback. Instability control was also shown with a pressure feedback sensor in the lower temperature region upstream of the combustor. It was also demonstrated that the controller can prevent the instability from occurring while combustor operation was transitioning from a stable, low-power condition to a normally unstable high-power condition, thus enabling the high-power condition.

Active Flow Control with Thermoacoustic Actuators

DTIC Science & Technology

2014-01-31

AC power has been shown to produce large-amplitude acoustic waves [6]. The input AC current sinusoidally heats this device due to joule heating and...conventional metals, the heat capacity value for carbon-based material (carbon nanotubes/graphene) in consideration here is at least 2 orders of...magnitude smaller. Since the output acoustic power delivered to the surrounding flow field is related inversely to the material heat capacity C (i.e., Poutput

More Efficient Power Conversion for EVs: Gallium-Nitride Advanced Power Semiconductor and Packaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

2010-02-01

Broad Funding Opportunity Announcement Project: Delphi is developing power converters that are smaller and more energy efficient, reliable, and cost-effective than current power converters. Power converters rely on power transistors which act like a very precisely controlled on-off switch, controlling the electrical energy flowing through an electrical circuit. Most power transistors today use silicon (Si) semiconductors. However, Delphi is using semiconductors made with a thin layer of gallium-nitride (GaN) applied on top of the more conventional Si material. The GaN layer increases the energy efficiency of the power transistor and also enables the transistor to operate at much higher temperatures,more » voltages, and power-density levels compared to its Si counterpart. Delphi is packaging these high-performance GaN semiconductors with advanced electrical connections and a cooling system that extracts waste heat from both sides of the device to further increase the device’s efficiency and allow more electrical current to flow through it. When combined with other electronic components on a circuit board, Delphi’s GaN power transistor package will help improve the overall performance and cost-effectiveness of HEVs and EVs.« less

A Novel Vaping Machine Dedicated to Fully Controlling the Generation of E-Cigarette Emissions

PubMed Central

Soulet, Sébastien; Pairaud, Charly; Lalo, Hélène

2017-01-01

The accurate study of aerosol composition and nicotine release by electronic cigarettes is a major issue. In order to fully and correctly characterize aerosol, emission generation has to be completely mastered. This study describes an original vaping machine named Universal System for Analysis of Vaping (U-SAV), dedicated to vaping product study, enabling the control and real-time monitoring of applied flow rate and power. Repeatability and stability of the machine are demonstrated on flow rate, power regulation and e-liquid consumption. The emission protocol used to characterize the vaping machine is based on the AFNOR-XP-D90-300-3 standard (15 W power, 1 Ω atomizer resistance, 100 puffs collected per session, 1.1 L/min airflow rate). Each of the parameters has been verified with two standardized liquids by studying mass variations, power regulation and flow rate stability. U-SAV presents the required and necessary stability for the full control of emission generation. The U-SAV is recognised by the French association for standardization (AFNOR), European Committee for Standardization (CEN) and International Standards Organisation (ISO) as a vaping machine. It can be used to highlight the influence of the e-liquid composition, user behaviour and nature of the device, on the e-liquid consumption and aerosol composition. PMID:29036888

A Novel Vaping Machine Dedicated to Fully Controlling the Generation of E-Cigarette Emissions.

PubMed

Soulet, Sébastien; Pairaud, Charly; Lalo, Hélène

2017-10-14

The accurate study of aerosol composition and nicotine release by electronic cigarettes is a major issue. In order to fully and correctly characterize aerosol, emission generation has to be completely mastered. This study describes an original vaping machine named Universal System for Analysis of Vaping (U-SAV), dedicated to vaping product study, enabling the control and real-time monitoring of applied flow rate and power. Repeatability and stability of the machine are demonstrated on flow rate, power regulation and e-liquid consumption. The emission protocol used to characterize the vaping machine is based on the AFNOR-XP-D90-300-3 standard (15 W power, 1 Ω atomizer resistance, 100 puffs collected per session, 1.1 L/min airflow rate). Each of the parameters has been verified with two standardized liquids by studying mass variations, power regulation and flow rate stability. U-SAV presents the required and necessary stability for the full control of emission generation. The U-SAV is recognised by the French association for standardization (AFNOR), European Committee for Standardization (CEN) and International Standards Organisation (ISO) as a vaping machine. It can be used to highlight the influence of the e-liquid composition, user behaviour and nature of the device, on the e-liquid consumption and aerosol composition.

Alternative Fuels Data Center: How Do All-Electric Cars Work?

Science.gov Websites

charge while charging the pack. Power electronics controller: This unit manages the flow of electrical of the engine, electric motor, power electronics, and other components. Traction battery pack: Stores

Power flow control using distributed saturable reactors

DOEpatents

Dimitrovski, Aleksandar D.

2016-02-13

A magnetic amplifier includes a saturable core having a plurality of legs. Control windings wound around separate legs are spaced apart from each other and connected in series in an anti-symmetric relation. The control windings are configured in such a way that a biasing magnetic flux arising from a control current flowing through one of the plurality of control windings is substantially equal to the biasing magnetic flux flowing into a second of the plurality of control windings. The flow of the control current through each of the plurality of control windings changes the reactance of the saturable core reactor by driving those portions of the saturable core that convey the biasing magnetic flux in the saturable core into saturation. The phasing of the control winding limits a voltage induced in the plurality of control windings caused by a magnetic flux passing around a portion of the saturable core.

A Comparative Study on Quantitative Assessment of Blood Flow and Vascularization in Polycystic Ovary Syndrome Patients and Normal Women Using Three-Dimensional Power Doppler Ultrasonography.

PubMed

Garg, Nitasha; Khaira, Harkiran Kaur; Kaur, Manjot; Sinha, Smita

2018-04-01

To compare the quantitative assessment of blood flow and vascularization of ovaries in polycystic ovary syndrome patients and normal women using three-dimensional power Doppler ultrasonography. This cross-sectional quantitative study was conducted on women of reproductive age group (15-45 years) attending Gynaecology OPD AIMSR, Bathinda, Punjab. Thirty women were enrolled in polycystic ovarian syndrome (PCOS) group and 30 healthy women in control group. Women were categorized as polycystic ovary syndrome according to Rotterdam's criteria. The women with PCOS underwent transvaginal USG Doppler on day 6 of the cycle using 3D power Doppler USG equipment (GE Voluson E8), and vascularization index (VI), flow index (FI) and vascularization flow index (VFI) were measured. The mean values of VI, FI and VFI measured by power Doppler ultrasonography were significantly increased ( P value = 0.000) in women with PCOS when compared with healthy women. This study suggests that blood flow and vascularization measured by 3D power Doppler ultrasonography in ovaries of polycystic ovary syndrome patients were significantly more than the ovaries of normal women.

Two phase exhaust for internal combustion engine

DOEpatents

Vuk, Carl T [Denver, IA

2011-11-29

An internal combustion engine having a reciprocating multi cylinder internal combustion engine with multiple valves. At least a pair of exhaust valves are provided and each supply a separate power extraction device. The first exhaust valves connect to a power turbine used to provide additional power to the engine either mechanically or electrically. The flow path from these exhaust valves is smaller in area and volume than a second flow path which is used to deliver products of combustion to a turbocharger turbine. The timing of the exhaust valve events is controlled to produce a higher grade of energy to the power turbine and enhance the ability to extract power from the combustion process.

Development of an Unmanned Air Research Vehicle for Supermaneuverability Studies

DTIC Science & Technology

1990-03-29

VORTEX CONTROL Another emerging concept involves strake- generated vortex interactions, which improves maneuverability using non-linear lift generated by...undisturbed flow and is capable of prcJucing powerful vortex flow fields at high angles of attack. Asymmetrical vort ,;x control is feasible with actuated...control configuration, serves as an initial test vehicle for supermaneuverability analysis . Due to the relatively small scale of the UAV and the use of

Liquid metal heat sink for high-power laser diodes

NASA Astrophysics Data System (ADS)

Vetrovec, John; Litt, Amardeep S.; Copeland, Drew A.; Junghans, Jeremy; Durkee, Roger

2013-02-01

We report on the development of a novel, ultra-low thermal resistance active heat sink (AHS) for thermal management of high-power laser diodes (HPLD) and other electronic and photonic components. AHS uses a liquid metal coolant flowing at high speed in a miniature closed and sealed loop. The liquid metal coolant receives waste heat from an HPLD at high flux and transfers it at much reduced flux to environment, primary coolant fluid, heat pipe, or structure. Liquid metal flow is maintained electromagnetically without any moving parts. Velocity of liquid metal flow can be controlled electronically, thus allowing for temperature control of HPLD wavelength. This feature also enables operation at a stable wavelength over a broad range of ambient conditions. Results from testing an HPLD cooled by AHS are presented.

Assessing the potential for improved scramjet performance through application of electromagnetic flow control

NASA Astrophysics Data System (ADS)

Lindsey, Martin Forrester

Sustained hypersonic flight using scramjet propulsion is the key technology bridging the gap between turbojets and the exoatmospheric environment where a rocket is required. Recent efforts have focused on electromagnetic (EM) flow control to mitigate the problems of high thermomechanical loads and low propulsion efficiencies associated with scramjet propulsion. This research effort is the first flight-scale, three-dimensional computational analysis of a realistic scramjet to determine how EM flow control can improve scramjet performance. Development of a quasi-one dimensional design tool culminated in the first open source geometry of an entire scramjet flowpath. This geometry was then tested extensively with the Air Force Research Laboratory's three-dimensional Navier-Stokes and EM coupled computational code. As part of improving the model fidelity, a loosely coupled algorithm was developed to incorporate thermochemistry. This resulted in the only open-source model of fuel injection, mixing and combustion in a magnetogasdynamic (MGD) flow controlled engine. In addition, a control volume analysis tool with an electron beam ionization model was presented for the first time in the context of the established computational method used. Local EM flow control within the internal inlet greatly impacted drag forces and wall heat transfer but was only marginally successful in raising the average pressure entering the combustor. The use of an MGD accelerator to locally increase flow momentum was an effective approach to improve flow into the scramjet's isolator. Combustor-based MGD generators proved superior to the inlet generator with respect to power density and overall engine efficiency. MGD acceleration was shown to be ineffective in improving overall performance, with all of the bypass engines having approximately 33% more drag than baseline and none of them achieving a self-powered state.

Alternative Fuels Data Center: How Do Plug-In Hybrid Electric Cars Work?

Science.gov Websites

the pack. Power electronics controller: This unit manages the flow of electrical energy delivered by , electric motor, power electronics, and other components. Traction battery pack: Stores electricity for use

A 400-kWe high-efficiency steam turbine for industrial cogeneration

NASA Technical Reports Server (NTRS)

Leibowitz, H. M.

1982-01-01

An advanced state-of-the-art steam turbine-generator developed to serve as the power conversion subsystem for the Department of Energy's Sandia National Laboratories' Solar Total-Energy Project (STEP) is described. The turbine-generator, which is designed to provide 400-kW of net electrical power, represents the largest turbine-generator built specifically for commercial solar-powered cogeneration. The controls for the turbine-generator incorporate a multiple, partial-arc entry to provide efficient off-design performance, as well as an extraction control scheme to permit extraction flow regulation while maintaining 110-spsig pressure. Normal turbine operation is achieved while synchronized to a local utility and in a stand-alone mode. In both cases, the turbine-generator features automatic load control as well as remote start-up and shutdown capability. Tests totaling 200 hours were conducted to confirm the integrity of the turbine's mechanical structure and control function. Performance tests resulted in a measured inlet throttle flow of 8,450 pounds per hour, which was near design conditions.

Microwave power transmission system studies. Volume 2: Introduction, organization, environmental and spaceborne systems analyses

NASA Technical Reports Server (NTRS)

Maynard, O. E.; Brown, W. C.; Edwards, A.; Haley, J. T.; Meltz, G.; Howell, J. M.; Nathan, A.

1975-01-01

Introduction, organization, analyses, conclusions, and recommendations for each of the spaceborne subsystems are presented. Environmental effects - propagation analyses are presented with appendices covering radio wave diffraction by random ionospheric irregularities, self-focusing plasma instabilities and ohmic heating of the D-region. Analyses of dc to rf conversion subsystems and system considerations for both the amplitron and the klystron are included with appendices for the klystron covering cavity circuit calculations, output power of the solenoid-focused klystron, thermal control system, and confined flow focusing of a relativistic beam. The photovoltaic power source characteristics are discussed as they apply to interfacing with the power distribution flow paths, magnetic field interaction, dc to rf converter protection, power distribution including estimates for the power budget, weights, and costs. Analyses for the transmitting antenna consider the aperture illumination and size, with associated efficiencies and ground power distributions. Analyses of subarray types and dimensions, attitude error, flatness, phase error, subarray layout, frequency tolerance, attenuation, waveguide dimensional tolerances, mechanical including thermal considerations are included. Implications associated with transportation, assembly and packaging, attitude control and alignment are discussed. The phase front control subsystem, including both ground based pilot signal driven adaptive and ground command approaches with their associated phase errors, are analyzed.

Techniques for enhancing durability and equivalence ratio control in a rich-lean, three-stage ground power gas turbine combustor

NASA Technical Reports Server (NTRS)

Schultz, D. F.

1982-01-01

Rig tests of a can-type combustor were performed to demonstrate two advanced ground power engine combustor concepts: steam cooled rich-burn combustor primary zones for enhanced durability; and variable combustor geometry for three stage combustion equivalence ratio control. Both concepts proved to be highly successful in achieving their desired objectives. The steam cooling reduced peak liner temperatures to less than 800 K. This offers the potential of both long life and reduced use of strategic materials for liner fabrication. Three degrees of variable geometry were successfully implemented to control airflow distribution within the combustor. One was a variable blade angle axial flow air swirler to control primary airflow while the other two consisted of rotating bands to control secondary and tertiary or dilution air flow.

Statistical analysis of cascading failures in power grids

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chertkov, Michael; Pfitzner, Rene; Turitsyn, Konstantin

2010-12-01

We introduce a new microscopic model of cascading failures in transmission power grids. This model accounts for automatic response of the grid to load fluctuations that take place on the scale of minutes, when optimum power flow adjustments and load shedding controls are unavailable. We describe extreme events, caused by load fluctuations, which cause cascading failures of loads, generators and lines. Our model is quasi-static in the causal, discrete time and sequential resolution of individual failures. The model, in its simplest realization based on the Directed Current description of the power flow problem, is tested on three standard IEEE systemsmore » consisting of 30, 39 and 118 buses. Our statistical analysis suggests a straightforward classification of cascading and islanding phases in terms of the ratios between average number of removed loads, generators and links. The analysis also demonstrates sensitivity to variations in line capacities. Future research challenges in modeling and control of cascading outages over real-world power networks are discussed.« less

Optimal Operation Method of Smart House by Controllable Loads based on Smart Grid Topology

NASA Astrophysics Data System (ADS)

Yoza, Akihiro; Uchida, Kosuke; Yona, Atsushi; Senju, Tomonobu

2013-08-01

From the perspective of global warming suppression and depletion of energy resources, renewable energy such as wind generation (WG) and photovoltaic generation (PV) are getting attention in distribution systems. Additionally, all electrification apartment house or residence such as DC smart house have increased in recent years. However, due to fluctuating power from renewable energy sources and loads, supply-demand balancing fluctuations of power system become problematic. Therefore, "smart grid" has become very popular in the worldwide. This article presents a methodology for optimal operation of a smart grid to minimize the interconnection point power flow fluctuations. To achieve the proposed optimal operation, we use distributed controllable loads such as battery and heat pump. By minimizing the interconnection point power flow fluctuations, it is possible to reduce the maximum electric power consumption and the electric cost. This system consists of photovoltaics generator, heat pump, battery, solar collector, and load. In order to verify the effectiveness of the proposed system, MATLAB is used in simulations.

Multi-mode evaluation of power-maximizing cross-flow turbine controllers

DOE PAGES

Forbush, Dominic; Cavagnaro, Robert J.; Donegan, James; ...

2017-09-21

A general method for predicting and evaluating the performance of three candidate cross-flow turbine power-maximizing controllers is presented in this paper using low-order dynamic simulation, scaled laboratory experiments, and full-scale field testing. For each testing mode and candidate controller, performance metrics quantifying energy capture (ability of a controller to maximize power), variation in torque and rotation rate (related to drive train fatigue), and variation in thrust loads (related to structural fatigue) are quantified for two purposes. First, for metrics that could be evaluated across all testing modes, we considered the accuracy with which simulation or laboratory experiments could predict performancemore » at full scale. Second, we explored the utility of these metrics to contrast candidate controller performance. For these turbines and set of candidate controllers, energy capture was found to only differentiate controller performance in simulation, while the other explored metrics were able to predict performance of the full-scale turbine in the field with various degrees of success. Finally, effects of scale between laboratory and full-scale testing are considered, along with recommendations for future improvements to dynamic simulations and controller evaluation.« less

Multi-mode evaluation of power-maximizing cross-flow turbine controllers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Forbush, Dominic; Cavagnaro, Robert J.; Donegan, James

A general method for predicting and evaluating the performance of three candidate cross-flow turbine power-maximizing controllers is presented in this paper using low-order dynamic simulation, scaled laboratory experiments, and full-scale field testing. For each testing mode and candidate controller, performance metrics quantifying energy capture (ability of a controller to maximize power), variation in torque and rotation rate (related to drive train fatigue), and variation in thrust loads (related to structural fatigue) are quantified for two purposes. First, for metrics that could be evaluated across all testing modes, we considered the accuracy with which simulation or laboratory experiments could predict performancemore » at full scale. Second, we explored the utility of these metrics to contrast candidate controller performance. For these turbines and set of candidate controllers, energy capture was found to only differentiate controller performance in simulation, while the other explored metrics were able to predict performance of the full-scale turbine in the field with various degrees of success. Finally, effects of scale between laboratory and full-scale testing are considered, along with recommendations for future improvements to dynamic simulations and controller evaluation.« less

Dynamic Modeling and Control of Nuclear Reactors Coupled to Closed-Loop Brayton Cycle Systems using SIMULINK{sup TM}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wright, Steven A.; Sanchez, Travis

2005-02-06

The operation of space reactors for both in-space and planetary operations will require unprecedented levels of autonomy and control. Development of these autonomous control systems will require dynamic system models, effective control methodologies, and autonomous control logic. This paper briefly describes the results of reactor, power-conversion, and control models that are implemented in SIMULINK{sup TM} (Simulink, 2004). SIMULINK{sup TM} is a development environment packaged with MatLab{sup TM} (MatLab, 2004) that allows the creation of dynamic state flow models. Simulation modules for liquid metal, gas cooled reactors, and electrically heated systems have been developed, as have modules for dynamic power-conversion componentsmore » such as, ducting, heat exchangers, turbines, compressors, permanent magnet alternators, and load resistors. Various control modules for the reactor and the power-conversion shaft speed have also been developed and simulated. The modules are compiled into libraries and can be easily connected in different ways to explore the operational space of a number of potential reactor, power-conversion system configurations, and control approaches. The modularity and variability of these SIMULINK{sup TM} models provides a way to simulate a variety of complete power generation systems. To date, both Liquid Metal Reactors (LMR), Gas Cooled Reactors (GCR), and electric heaters that are coupled to gas-dynamics systems and thermoelectric systems have been simulated and are used to understand the behavior of these systems. Current efforts are focused on improving the fidelity of the existing SIMULINK{sup TM} modules, extending them to include isotopic heaters, heat pipes, Stirling engines, and on developing state flow logic to provide intelligent autonomy. The simulation code is called RPC-SIM (Reactor Power and Control-Simulator)« less

Method for controlling start-up and steady state performance of a closed split flow recompression brayton cycle

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pasch, James Jay

A method of resolving a balanced condition that generates control parameters for start-up and steady state operating points and various component and cycle performances for a closed split flow recompression cycle system. The method provides for improved control of a Brayton cycle thermal to electrical power conversion system. The method may also be used for system design, operational simulation and/or parameter prediction.

Power and energy ratios in mechanical CVT drive control

NASA Astrophysics Data System (ADS)

Balakin, P. D.; Stripling, L. O.

2017-06-01

Being based on the principle of providing the systems with adaptation property to the real parameters and operational condition, the mechanical system capable to control automatically the components of convertible power is offered and this allows providing stationary operation of the vehicle engine in the terms of variable external loading. This is achieved by drive control integrated in the power transmission, which implements an additional degree of freedom and operates on the basis of the laws of motion, with the energy of the main power flow by changing automatically the kinematic characteristics of the power transmission, this system being named CVT. The power and energy ratios found allow performing the necessary design calculations of the sections and the links of the mechanical CVT scheme.

Regulated-current dc power supply for gaseous-discharge lamps

NASA Technical Reports Server (NTRS)

Freeman, W.; Huguenin, D.

1970-01-01

Controlled current source having a high output resistance feeds continuous-flow hydrogen lamps in vacuum-ultraviolet photometric equipment. The power supply, also used with low-pressure sealed lamps, has a short recovery time and smooth regulation without overshoot.

Towards feasible and effective predictive wavefront control for adaptive optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Poyneer, L A; Veran, J

We have recently proposed Predictive Fourier Control, a computationally efficient and adaptive algorithm for predictive wavefront control that assumes frozen flow turbulence. We summarize refinements to the state-space model that allow operation with arbitrary computational delays and reduce the computational cost of solving for new control. We present initial atmospheric characterization using observations with Gemini North's Altair AO system. These observations, taken over 1 year, indicate that frozen flow is exists, contains substantial power, and is strongly detected 94% of the time.

Heat transfer and oil flow studies on a single-stage-to-orbit control-configured winged entry vehicle

NASA Technical Reports Server (NTRS)

Helms, V. T., III; Bradley, P. F.

1984-01-01

Results are presented for oil flow and phase change paint heat transfer tests conducted on a 0.006 scale model of a proposed single stage to orbit control configured vehicle. The data were taken at angles of attack up to 40 deg at a free stream Mach number of 10 for Reynolds numbers based on model length of 0.5 x 10 to the 6th power, 1.0 x 10 to the 6th power and 2.0 x 10 to the 6th power. The magnitude and distribution of heating are characterized in terms of angle of attack and Reynolds number aided by an analysis of the flow data which are used to suggest the presence of various three dimensional flow structures that produce the observed heating patterns. Of particular interest are streak heating patterns that result in high localized heat transfer rates on the wing windward surface at low to moderate angles of attack. These streaks are caused by the bow-shock/wing-shock interaction and formation of the wing-shock. Embedded vorticity was found to be associated with these interactions.

Unsteady Flow Simulation of a Sweeping Jet Actuator Using a Lattice-Boltzmann Method

NASA Technical Reports Server (NTRS)

Duda, B.; Wessels, M.; Fares, E.; Vatsa, V.

2016-01-01

Active flow control technology is increasingly used in aerospace applications to control flow separation and to improve aerodynamic performance. In this paper, PowerFLOW is used to simulate the flow through a sweeping jet actuator at two different pressure ratios. The lower pressure ratio leads to a high subsonic flow, whereas the high pressure ratio produces a choked flow condition. Comparison of numerical results with experimental data is shown, which includes qualitatively good agreement of pressure histories and spectra. PIV measurements are also available but the simulation overestimates mean and fluctuation quantities outside the actuator. If supply pressure is matched at one point inside the mixing chamber a good qualitative agreement is achieved at all other monitor points.

Numerical Simulation of Fluidic Actuators for Flow Control Applications

NASA Technical Reports Server (NTRS)

Vasta, Veer N.; Koklu, Mehti; Wygnanski, Israel L.; Fares, Ehab

2012-01-01

Active flow control technology is finding increasing use in aerospace applications to control flow separation and improve aerodynamic performance. In this paper we examine the characteristics of a class of fluidic actuators that are being considered for active flow control applications for a variety of practical problems. Based on recent experimental work, such actuators have been found to be more efficient for controlling flow separation in terms of mass flow requirements compared to constant blowing and suction or even synthetic jet actuators. The fluidic actuators produce spanwise oscillating jets, and therefore are also known as sweeping jets. The frequency and spanwise sweeping extent depend on the geometric parameters and mass flow rate entering the actuators through the inlet section. The flow physics associated with these actuators is quite complex and not fully understood at this time. The unsteady flow generated by such actuators is simulated using the lattice Boltzmann based solver PowerFLOW R . Computed mean and standard deviation of velocity profiles generated by a family of fluidic actuators in quiescent air are compared with experimental data. Simulated results replicate the experimentally observed trends with parametric variation of geometry and inflow conditions.

Variable Frequency Diverter Actuation for Flow Control

NASA Technical Reports Server (NTRS)

Culley, Dennis E.

2006-01-01

The design and development of an actively controlled fluidic actuator for flow control applications is explored. The basic device, with one input and two output channels, takes advantage of the Coanda effect to force a fluid jet to adhere to one of two axi-symmetric surfaces. The resultant flow is bi-stable, producing a constant flow from one output channel, until a disturbance force applied at the control point causes the flow to switch to the alternate output channel. By properly applying active control the output flows can be manipulated to provide a high degree of modulation over a wide and variable range of frequency and duty cycle. In this study the momentary operative force is applied by small, high speed isolation valves of which several different types are examined. The active fluidic diverter actuator is shown to work in several configurations including that in which the operator valves are referenced to atmosphere as well as to a source common with the power stream.

Flash chemistry: flow chemistry that cannot be done in batch.

PubMed

Yoshida, Jun-ichi; Takahashi, Yusuke; Nagaki, Aiichiro

2013-11-04

Flash chemistry based on high-resolution reaction time control using flow microreactors enables chemical reactions that cannot be done in batch and serves as a powerful tool for laboratory synthesis of organic compounds and for production in chemical and pharmaceutical industries.

Reducing current reversal time in electric motor control

DOEpatents

Bredemann, Michael V

2014-11-04

The time required to reverse current flow in an electric motor is reduced by exploiting inductive current that persists in the motor when power is temporarily removed. Energy associated with this inductive current is used to initiate reverse current flow in the motor.

Adjoint-Baed Optimal Control on the Pitch Angle of a Single-Bladed Vertical-Axis Wind Turbine

NASA Astrophysics Data System (ADS)

Tsai, Hsieh-Chen; Colonius, Tim

2017-11-01

Optimal control on the pitch angle of a NACA0018 single-bladed vertical-axis wind turbine (VAWT) is numerically investigated at a low Reynolds number of 1500. With fixed tip-speed ratio, the input power is minimized and mean tangential force is maximized over a specific time horizon. The immersed boundary method is used to simulate the two-dimensional, incompressible flow around a horizontal cross section of the VAWT. The problem is formulated as a PDE constrained optimization problem and an iterative solution is obtained using adjoint-based conjugate gradient methods. By the end of the longest control horizon examined, two controls end up with time-invariant pitch angles of about the same magnitude but with the opposite signs. The results show that both cases lead to a reduction in the input power but not necessarily an enhancement in the mean tangential force. These reductions in input power are due to the removal of a power-damaging phenomenon that occurs when a vortex pair is captured by the blade in the upwind-half region of a cycle. This project was supported by Caltech FLOWE center/Gordon and Betty Moore Foundation.

Impact of transvaginal hydrolaparoscopy ovarian drilling on ovarian stromal blood flow and ovarian volume in clomiphene citrate-resistant PCOS patients: a case-control study.

PubMed

Giampaolino, Pierluigi; Morra, Ilaria; De Rosa, Nicoletta; Cagnacci, Angelo; Pellicano, Massimiliano; Di Carlo, Costantino; Nappi, Carmine; Bifulco, Giuseppe

2017-09-01

Polycystic ovarian syndrome (PCOS) is the most common endocrine disorder in gynecology. In PCOS patients vascularization parameters are altered. Transvaginal hydrolaparoscopy (THL) is a mini-invasive approach for ovarian drilling in PCOS patients. In this study, we assessed the effect of ovarian drilling using THL on ovarian volume (OV) and vascularization index (VI) using 3D power Doppler ultrasonography in CC-resistant PCOS patients. A case-control study on 123 CC-resistant PCOS women who underwent THL ovarian drilling was performed. Patients underwent 3D ultrasound and power Doppler to measure VI, flow index (FI), vascularization flow index (VFI) and to evaluate OV before and after the procedure, at six months, and on the early follicular phase of the menstrual cycle. After THL ovarian drilling, OV and power Doppler flow indices were significantly reduced compared to pre-operative values (OV: 7.85 versus 11.72 cm 3 , p < 0.01; VI: 2.50 versus 4.81, p < 0.01; VFI: 1.10 versus 2.16, p < 0.01; FI: 32.05 versus 35.37, p < 0.01). In conclusion, THL ovarian drilling seems to reduce OV and 3D power Doppler indices, and could therefore be a viable alternative to LOD in PCOS patients resistant to medical therapy.

Solid state rapid thermocycling

DOEpatents

Beer, Neil Reginald; Spadaccini, Christopher

2014-05-13

The rapid thermal cycling of a material is targeted. A solid state heat exchanger with a first well and second well is coupled to a power module. A thermoelectric element is coupled to the first well, the second well, and the power module, is configured to transfer thermal energy from the first well to the second well when current from the power module flows through the thermoelectric element in a first direction, and is configured to transfer thermal energy from the second well to the first well when current from the power module flows through the thermoelectric element in a second direction. A controller may be coupled to the thermoelectric elements, and may switch the direction of current flowing through the thermoelectric element in response to a determination by sensors coupled to the wells that the amount of thermal energy in the wells falls below or exceeds a pre-determined threshold.

Modeling and control of hybrid wind/photovoltaic/fuel cell distributed generation systems

NASA Astrophysics Data System (ADS)

Wang, Caisheng

Due to ever increasing energy consumption, rising public awareness of environmental protection, and steady progress in power deregulation, alternative (i.e., renewable and fuel cell based) distributed generation (DG) systems have attracted increased interest. Wind and photovoltaic (PV) power generation are two of the most promising renewable energy technologies. Fuel cell (FC) systems also show great potential in DG applications of the future due to their fast technology development and many merits they have, such as high efficiency, zero or low emission (of pollutant gases) and flexible modular structure. The modeling and control of a hybrid wind/PV/FC DG system is addressed in this dissertation. Different energy sources in the system are integrated through an AC bus. Dynamic models for the main system components, namely, wind energy conversion system (WECS), PV energy conversion system (PVECS), fuel cell, electrolyzer, power electronic interfacing circuits, battery, hydrogen storage tank, gas compressor and gas pressure regulator, are developed. Two types of fuel cells have been modeled in this dissertation: proton exchange membrane fuel cell (PEMFC) and solid oxide fuel cell (SOFC). Power control of a grid-connected FC system as well as load mitigation control of a stand-alone FC system are investigated. The pitch angle control for WECS, the maximum power point tracking (MPPT) control for PVECS, and the control for electrolyzer and power electronic devices, are also addressed in the dissertation. Based on the dynamic component models, a simulation model for the proposed hybrid energy system has been developed using MATLAB/Simulink. The overall power management strategy for coordinating the power flows among the different energy sources is presented in the dissertation. Simulation studies have been carried out to verify the system performance under different scenarios using a practical load profile and real weather data. The results show that the overall power management strategy is effective and the power flows among the different energy sources and the load demand is balanced successfully. The DG's impacts on the existing power system are also investigated in this dissertation. Analytical methods for finding optimal sites to deploy DG sources in power systems are presented and verified with simulation studies.

Active Wake Redirection Control to Improve Energy Yield (Poster)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Churchfield, M. J.; Fleming, P.; DeGeorge, E.

Wake effects can dramatically reduce the efficiency of waked turbines relative to the unwaked turbines. Wakes can be deflected, or 'redirected,' by applying yaw misalignment to the turbines. Yaw misalignment causes part of the rotor thrust vector to be pointed in the cross-stream direction, deflecting the flow and the wake. Yaw misalignment reduces power production, but the global increase in wind plant power due to decreased wake effect creates a net increase in power production. It is also a fairly simple control idea to implement at existing or new wind plants. We performed high-fidelity computational fluid dynamics simulations of themore » wake flow of the proposed Fishermen's Atlantic City Windfarm (FACW) that predict that under certain waking conditions, wake redirection can increase plant efficiency by 10%. This means that by applying wake redirection control, for a given watersheet area, a wind plant can either produce more power, or the same amount of power can be produced with a smaller watersheet area. With the power increase may come increased loads, though, due to the yaw misalignment. If misalignment is applied properly, or if layered with individual blade pitch control, though, the load increase can be mitigated. In this talk we will discuss the concept of wake redirection through yaw misalignment and present our CFD results of the FACW project. We will also discuss the implications of wake redirection control on annual energy production, and finally we will discuss plans to implement wake redirection control at FACW when it is operational.« less

Microfluidic on-chip fluorescence-activated interface control system

PubMed Central

Haiwang, Li; Nguyen, N. T.; Wong, T. N.; Ng, S. L.

2010-01-01

A microfluidic dynamic fluorescence-activated interface control system was developed for lab-on-a-chip applications. The system consists of a straight rectangular microchannel, a fluorescence excitation source, a detection sensor, a signal conversion circuit, and a high-voltage feedback system. Aqueous NaCl as conducting fluid and aqueous glycerol as nonconducting fluid were introduced to flow side by side into the straight rectangular microchannel. Fluorescent dye was added to the aqueous NaCl to work as a signal representing the interface position. Automatic control of the liquid interface was achieved by controlling the electroosmotic effect that exists only in the conducting fluid using a high-voltage feedback system. A LABVIEW program was developed to control the output of high-voltage power supply according the actual interface position, and then the interface position is modified as the output of high-voltage power supply. At last, the interface can be moved to the desired position automatically using this feedback system. The results show that the system presented in this paper can control an arbitrary interface location in real time. The effects of viscosity ratio, flow rates, and polarity of electric field were discussed. This technique can be extended to switch the sample flow and droplets automatically. PMID:21173886

High-bandwidth continuous-flow arc furnace

DOEpatents

Hardt, David E.; Lee, Steven G.

1996-01-01

A high-bandwidth continuous-flow arc furnace for stream welding applications includes a metal mass contained in a crucible having an orifice. A power source charges an electrode for generating an arc between the electrode and the mass. The arc heats the metal mass to a molten state. A pressurized gas source propels the molten metal mass through the crucible orifice in a continuous stream. As the metal is ejected, a metal feeder replenishes the molten metal bath. A control system regulates the electrode current, shielding gas pressure, and metal source to provide a continuous flow of molten metal at the crucible orifice. Independent control over the electrode current and shield gas pressure decouples the metal flow temperature and the molten metal flow rate, improving control over resultant weld characteristics.

High-bandwidth continuous-flow arc furnace

DOEpatents

Hardt, D.E.; Lee, S.G.

1996-08-06

A high-bandwidth continuous-flow arc furnace for stream welding applications includes a metal mass contained in a crucible having an orifice. A power source charges an electrode for generating an arc between the electrode and the mass. The arc heats the metal mass to a molten state. A pressurized gas source propels the molten metal mass through the crucible orifice in a continuous stream. As the metal is ejected, a metal feeder replenishes the molten metal bath. A control system regulates the electrode current, shielding gas pressure, and metal source to provide a continuous flow of molten metal at the crucible orifice. Independent control over the electrode current and shield gas pressure decouples the metal flow temperature and the molten metal flow rate, improving control over resultant weld characteristics. 4 figs.

Enhancing power density of biophotovoltaics by decoupling storage and power delivery

NASA Astrophysics Data System (ADS)

Saar, Kadi L.; Bombelli, Paolo; Lea-Smith, David J.; Call, Toby; Aro, Eva-Mari; Müller, Thomas; Howe, Christopher J.; Knowles, Tuomas P. J.

2018-01-01

Biophotovoltaic devices (BPVs), which use photosynthetic organisms as active materials to harvest light, have a range of attractive features relative to synthetic and non-biological photovoltaics, including their environmentally friendly nature and ability to self-repair. However, efficiencies of BPVs are currently lower than those of synthetic analogues. Here, we demonstrate BPVs delivering anodic power densities of over 0.5 W m-2, a value five times that for previously described BPVs. We achieved this through the use of cyanobacterial mutants with increased electron export characteristics together with a microscale flow-based design that allowed independent optimization of the charging and power delivery processes, as well as membrane-free operation by exploiting laminar flow to separate the catholyte and anolyte streams. These results suggest that miniaturization of active elements and flow control for decoupled operation and independent optimization of the core processes involved in BPV design are effective strategies for enhancing power output and thus the potential of BPVs as viable systems for sustainable energy generation.

Coordinated Control of Cross-Flow Turbines

NASA Astrophysics Data System (ADS)

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.

Effect of rod gap spacing on a suction panel for laminar flow and noise control in supersonic wind tunnels. M.S. Thesis - Old Dominion Univ.

NASA Technical Reports Server (NTRS)

Harvey, W. D.

1975-01-01

Results are presented of a coordinated experimental and theoretical study of a sound shield concept which aims to provide a means of noise reduction in the test section of supersonic wind tunnels at high Reynolds numbers. The model used consists of a planar array of circular rods aligned with the flow, with adjustable gaps between them for boundary layer removal by suction, i.e., laminar flow control. One of the basic requirements of the present sound shield concept is to achieve sonic cross flow through the gaps in order to prevent lee-side flow disturbances from penetrating back into the shielded region. Tests were conducted at Mach 6 over a local unit Reynolds number range from about 1.2 x 10 to the 6th power to 13.5 x 10 to the 6th power per foot. Measurements of heat transfer, static pressure, and sound levels were made to establish the transition characteristics of the boundary layer on the rod array and the sound shielding effectiveness.

14 CFR 23.1143 - Engine controls.

Code of Federal Regulations, 2014 CFR

2014-01-01

... independent of those for every other engine or supercharger. (e) For each fluid injection (other than fuel... flow of the injection fluid is adequately controlled. (f) If a power, thrust, or a fuel control (other than a mixture control) incorporates a fuel shutoff feature, the control must have a means to prevent...

14 CFR 23.1143 - Engine controls.

Code of Federal Regulations, 2013 CFR

2013-01-01

... independent of those for every other engine or supercharger. (e) For each fluid injection (other than fuel... flow of the injection fluid is adequately controlled. (f) If a power, thrust, or a fuel control (other than a mixture control) incorporates a fuel shutoff feature, the control must have a means to prevent...

Design and construction of an airfoil with controlled flap

NASA Astrophysics Data System (ADS)

Amin, Md. Ruhul; Rahman, S. M. Mahbobur; Mashud, Mohammad; Rabbi, Md. Fazle

2017-06-01

For modern aircrafts maneuvering control and reduction of power loss is a matter of great concern in Aerodynamics. Separation of airflow over the wings of aircraft at high angle of attack or at other situations is a hindrance to proper maneuvering control. As flow separation increases drag force on the aircraft, it consumes excess power. For these reasons much effort and research has gone into the design of aerodynamic surfaces which delay flow separation and keep the local flow attached for as long as possible. One of the simple and cost-effective way is to use a hinged flap on the wing of the aircraft, which lifts and self-adjusts to a position dependent on the aerodynamic forces and flap weight due to reversed flow at increasing angle of attack. There is a limitation of this kind of process. At very high angles of attack, the reversed flow would cause the flap to tip forwards entirely and the effect of the flap would vanish. For recovering this limitation an idea of controlling the movement or rotation of the flap has been proposed in this paper. A light surface was selected as a flap and was coupled to the shaft of a servo motor, which was placed on a model airfoil. For controlling the angle of rotation of the motor as well as the flap arbitrarily, an electronic circuit comprising necessary components was designed and applied to the servo motor successfully.

THYME: Toolkit for Hybrid Modeling of Electric Power Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nutaro Kalyan Perumalla, James Joseph

2011-01-01

THYME is an object oriented library for building models of wide area control and communications in electric power systems. This software is designed as a module to be used with existing open source simulators for discrete event systems in general and communication systems in particular. THYME consists of a typical model for simulating electro-mechanical transients (e.g., as are used in dynamic stability studies), data handling objects to work with CDF and PTI formatted power flow data, and sample models of discrete sensors and controllers.

Thermal Vacuum Testing of a Proto-flight Miniature Loop Heat Pipe with Two Evaporators and Two Condensers

NASA Technical Reports Server (NTRS)

Ku, Jentung; Ottenstein, Laura

2011-01-01

This paper describes thermal vacuum testing of a proto-flight miniature loop heat pipe (MLHP) with two evaporators and two condensers designed for future small systems applications requiring low mass, low power and compactness. Each evaporator contains a wick with an outer diameter of 6.35 mm, and each has its own integral compensation chamber (CC). Miniaturization of the loop components reduces the volume and mass of the thermal system. Multiple evaporators provide flexibility for placement of instruments that need to be maintained at the same temperature, and facilitate heat load sharing among instruments, reducing the auxiliary heater power requirement. A flow regulator is used to regulate heat dissipations between the two condensers, allowing flexible placement of radiators on the spacecraft. A thermoelectric converter (TEC) is attached to each CC for control of the operating temperature and enhancement of start-up success. Tests performed include start-up, power cycle, sink temperature cycle, high power and low power operation, heat load sharing, and operating temperature control. The proto-flight MLHP demonstrated excellent performance in the thermal vacuum test. The loop started successfully and operated stably under various evaporator heat loads and condenser sink temperatures. The TECs were able to maintain the loop operating temperature within b1K of the desired set point temperature at all power levels and all sink temperatures. The un-powered evaporator would automatically share heat from the other powered evaporator. The flow regulator was able to regulate the heat dissipation among the radiators and prevent vapor from flowing into the liquid line.

Enhanced High Performance Power Compensation Methodology by IPFC Using PIGBT-IDVR

PubMed Central

Arumugom, Subramanian; Rajaram, Marimuthu

2015-01-01

Currently, power systems are involuntarily controlled without high speed control and are frequently initiated, therefore resulting in a slow process when compared with static electronic devices. Among various power interruptions in power supply systems, voltage dips play a central role in causing disruption. The dynamic voltage restorer (DVR) is a process based on voltage control that compensates for line transients in the distributed system. To overcome these issues and to achieve a higher speed, a new methodology called the Parallel IGBT-Based Interline Dynamic Voltage Restorer (PIGBT-IDVR) method has been proposed, which mainly spotlights the dynamic processing of energy reloads in common dc-linked energy storage with less adaptive transition. The interline power flow controller (IPFC) scheme has been employed to manage the power transmission between the lines and the restorer method for controlling the reactive power in the individual lines. By employing the proposed methodology, the failure of a distributed system has been avoided and provides better performance than the existing methodologies. PMID:26613101

High quantum yield ZnO quantum dots synthesizing via an ultrasonication microreactor method.

PubMed

Yang, Weimin; Yang, Huafang; Ding, Wenhao; Zhang, Bing; Zhang, Le; Wang, Lixi; Yu, Mingxun; Zhang, Qitu

2016-11-01

Green emission ZnO quantum dots were synthesized by an ultrasonic microreactor. Ultrasonic radiation brought bubbles through ultrasonic cavitation. These bubbles built microreactor inside the microreactor. The photoluminescence properties of ZnO quantum dots synthesized with different flow rate, ultrasonic power and temperature were discussed. Flow rate, ultrasonic power and temperature would influence the type and quantity of defects in ZnO quantum dots. The sizes of ZnO quantum dots would be controlled by those conditions as well. Flow rate affected the reaction time. With the increasing of flow rate, the sizes of ZnO quantum dots decreased and the quantum yields first increased then decreased. Ultrasonic power changed the ultrasonic cavitation intensity, which affected the reaction energy and the separation of the solution. With the increasing of ultrasonic power, sizes of ZnO quantum dots first decreased then increased, while the quantum yields kept increasing. The effect of ultrasonic temperature on the photoluminescence properties of ZnO quantum dots was influenced by the flow rate. Different flow rate related to opposite changing trend. Moreover, the quantum yields of ZnO QDs synthesized by ultrasonic microreactor could reach 64.7%, which is higher than those synthesized only under ultrasonic radiation or only by microreactor. Copyright © 2016 Elsevier B.V. All rights reserved.

Fractionating power and outlet stream polydispersity in asymmetrical flow field-flow fractionation. Part I: isocratic operation.

PubMed

Williams, P Stephen

2016-05-01

Asymmetrical flow field-flow fractionation (As-FlFFF) has become the most commonly used of the field-flow fractionation techniques. However, because of the interdependence of the channel flow and the cross flow through the accumulation wall, it is the most difficult of the techniques to optimize, particularly for programmed cross flow operation. For the analysis of polydisperse samples, the optimization should ideally be guided by the predicted fractionating power. Many experimentalists, however, neglect fractionating power and rely on light scattering detection simply to confirm apparent selectivity across the breadth of the eluted peak. The size information returned by the light scattering software is assumed to dispense with any reliance on theory to predict retention, and any departure of theoretical predictions from experimental observations is therefore considered of no importance. Separation depends on efficiency as well as selectivity, however, and efficiency can be a strong function of retention. The fractionation of a polydisperse sample by field-flow fractionation never provides a perfectly separated series of monodisperse fractions at the channel outlet. The outlet stream has some residual polydispersity, and it will be shown in this manuscript that the residual polydispersity is inversely related to the fractionating power. Due to the strong dependence of light scattering intensity and its angular distribution on the size of the scattering species, the outlet polydispersity must be minimized if reliable size data are to be obtained from the light scattering detector signal. It is shown that light scattering detection should be used with careful control of fractionating power to obtain optimized analysis of polydisperse samples. Part I is concerned with isocratic operation of As-FlFFF, and part II with programmed operation.

Numerical and Experimental Methods for Wake Flow Analysis in Complex Terrain

NASA Astrophysics Data System (ADS)

Castellani, Francesco; Astolfi, Davide; Piccioni, Emanuele; Terzi, Ludovico

2015-06-01

Assessment and interpretation of the quality of wind farms power output is a non-trivial task, which poses at least three main challenges: reliable comprehension of free wind flow, which is stretched to the limit on very complex terrains, realistic model of how wake interactions resemble on the wind flow, awareness of the consequences on turbine control systems, including alignment patterns to the wind and, consequently, power output. The present work deals with an onshore wind farm in southern Italy, which has been a test case of IEA- Task 31 Wakebench project: 17 turbines, with 2.3 MW of rated power each, are sited on a very complex terrain. A cluster of machines is investigated through numerical and experimental methods: CFD is employed for simulating wind fields and power extraction, as well as wakes, are estimated through the Actuator Disc model. SCADA data mining techniques are employed for comparison between models and actual performances. The simulations are performed both on the real terrain and on flat terrain, in order to disentangle the effects of complex flow and wake effects. Attention is devoted to comparison between actual alignment patterns of the cluster of turbines and predicted flow deviation.

Control of a shock wave-boundary layer interaction using localized arc filament plasma actuators

NASA Astrophysics Data System (ADS)

Webb, Nathan Joseph

Supersonic flight is currently possible, but expensive. Inexpensive supersonic travel will require increased efficiency of high-speed air entrainment, an integral part of air-breathing propulsion systems. Although mixed compression inlet geometry can significantly improve entrainment efficiency, numerous Shock Wave-Boundary Layer Interactions (SWBLIs) are generated in this configuration. The boundary layer must therefore develop through multiple regions of adverse pressure gradient, causing it to thicken, and, in severe cases, separate. The associated increase in unsteadiness can have adverse effects on downstream engine hardware. The most severe consequence of these interactions is the increased aerodynamic blockage generated by the thickened boundary layer. If the increase is sufficient, it can choke the flow, causing inlet unstart, and resulting in a loss of thrust and high transient forces on the engine, airframe, and aircraft occupants. The potentially severe consequences associated with SWBLIs require flow control to ensure proper operation. Traditionally, boundary layer bleed has been used to control the interaction. Although this method is effective, it has inherent efficiency penalties. Localized Arc Filament Plasma Actuators (LAFPAs) are designed to generate perturbations for flow control. Natural flow instabilities act to amplify certain perturbations, allowing the LAFPAs to control the flow with minimal power input. LAFPAs also have the flexibility to maintain control over a variety of operating conditions. This work seeks to examine the effectiveness of LAFPAs as a separation control method for an oblique, impinging SWBLI. The low frequency unsteadiness in the reflected shock was thought to be the natural manifestation of a Kelvin-Helmholtz instability in the shear layer above the separation region. The LAFPAs were therefore placed upstream of the interaction to allow their perturbations to convect to the receptivity region (near the shear layer origin/separation line). Streamwise PIV measurements did not show that the boundary layer or separation region were energized by the actuation. The primary effect of the LAFPAs was the displacement of the reflected shock upstream. Jaunet et al. (2012) observed a similar shift in the reflected shock when they heated the wall beneath the boundary layer. A significantly greater power deposition was used in that work, and significantly larger shock displacements were observed. Although the LAFPAs output significantly less power (albeit in an unsteady, highly localized fashion), a parametric sweep strongly pointed to heating as the primary control mechanism. Further investigation and analysis showed that the near-wall heating of the flow by the plasma was the primary control mechanism of the LAFPAs, despite the small power input. The reflected shock was displaced by an increase in the separation region size, which was caused by the degradation of the upstream boundary layer. The LAFPAs degrade the upstream boundary layer through a variety of heating associated mechanisms: 1) Decreasing the density increases the mass flow deficit, 2) The altered skin-friction coefficient acts to retard the flow and make the velocity profile less full, and 3) The heating moves the sonic line further from the wall. Other mechanisms may also play a role.

Sliding mode controller for a photovoltaic pumping system

NASA Astrophysics Data System (ADS)

ElOugli, A.; Miqoi, S.; Boutouba, M.; Tidhaf, B.

2017-03-01

In this paper, a sliding mode control scheme (SMC) for maximum power point tracking controller for a photovoltaic pumping system, is proposed. The main goal is to maximize the flow rate for a water pump, by forcing the photovoltaic system to operate in its MPP, to obtain the maximum power that a PV system can deliver.And this, through the intermediary of a sliding mode controller to track and control the MPP by overcoming the power oscillation around the operating point, which appears in most implemented MPPT techniques. The sliding mode control approach is recognized as one of the efficient and powerful tools for nonlinear systems under uncertainty conditions.The proposed controller with photovoltaic pumping system is designed and simulated using MATLAB/SIMULINK environment. In addition, to evaluate its performances, a classical MPPT algorithm using perturb and observe (P&O) has been used for the same system to compare to our controller. Simulation results are shown.

Loop Heat Pipe Temperature Oscillation Induced by Gravity Assist and Reservoir Heating

NASA Technical Reports Server (NTRS)

Ku, Jentung; Garrison, Matthew; Patel, Deepak; Robinson, Franklin; Ottenstein, Laura

2015-01-01

The Laser Thermal Control System (LCTS) for the Advanced Topographic Laser Altimeter System (ATLAS) to be installed on NASA's Ice, Cloud, and Land Elevation Satellite (ICESat-2) consists of a constant conductance heat pipe and a loop heat pipe (LHP) with an associated radiator. During the recent thermal vacuum testing of the LTCS where the LHP condenser/radiator was placed in a vertical position above the evaporator and reservoir, it was found that the LHP reservoir control heater power requirement was much higher than the analytical model had predicted. Even with the control heater turned on continuously at its full power, the reservoir could not be maintained at its desired set point temperature. An investigation of the LHP behaviors found that the root cause of the problem was fluid flow and reservoir temperature oscillations, which led to persistent alternate forward and reversed flow along the liquid line and an imbalance between the vapor mass flow rate in the vapor line and liquid mass flow rate in the liquid line. The flow and temperature oscillations were caused by an interaction between gravity and reservoir heating, and were exacerbated by the large thermal mass of the instrument simulator which modulated the net heat load to the evaporator, and the vertical radiator/condenser which induced a variable gravitational pressure head. Furthermore, causes and effects of the contributing factors to flow and temperature oscillations intermingled.

Apparatus for Controlling Low Power Voltages in Space Based Processing Systems

NASA Technical Reports Server (NTRS)

Petrick, David J. (Inventor)

2017-01-01

A low power voltage control circuit for use in space missions includes a switching device coupled between an input voltage and an output voltage. The switching device includes a control input coupled to an enable signal, wherein the control input is configured to selectively turn the output voltage on or off based at least in part on the enable signal. A current monitoring circuit is coupled to the output voltage and configured to produce a trip signal, wherein the trip signal is active when a load current flowing through the switching device is determined to exceed a predetermined threshold and is inactive otherwise. The power voltage control circuit is constructed of space qualified components.

Estimation of cardiac reserve by peak power: validation and initial application of a simplified index

NASA Technical Reports Server (NTRS)

Armstrong, G. P.; Carlier, S. G.; Fukamachi, K.; Thomas, J. D.; Marwick, T. H.

1999-01-01

OBJECTIVES: To validate a simplified estimate of peak power (SPP) against true (invasively measured) peak instantaneous power (TPP), to assess the feasibility of measuring SPP during exercise and to correlate this with functional capacity. DESIGN: Development of a simplified method of measurement and observational study. SETTING: Tertiary referral centre for cardiothoracic disease. SUBJECTS: For validation of SPP with TPP, seven normal dogs and four dogs with dilated cardiomyopathy were studied. To assess feasibility and clinical significance in humans, 40 subjects were studied (26 patients; 14 normal controls). METHODS: In the animal validation study, TPP was derived from ascending aortic pressure and flow probe, and from Doppler measurements of flow. SPP, calculated using the different flow measures, was compared with peak instantaneous power under different loading conditions. For the assessment in humans, SPP was measured at rest and during maximum exercise. Peak aortic flow was measured with transthoracic continuous wave Doppler, and systolic and diastolic blood pressures were derived from brachial sphygmomanometry. The difference between exercise and rest simplified peak power (Delta SPP) was compared with maximum oxygen uptake (VO(2)max), measured from expired gas analysis. RESULTS: SPP estimates using peak flow measures correlated well with true peak instantaneous power (r = 0.89 to 0.97), despite marked changes in systemic pressure and flow induced by manipulation of loading conditions. In the human study, VO(2)max correlated with Delta SPP (r = 0.78) better than Delta ejection fraction (r = 0.18) and Delta rate-pressure product (r = 0.59). CONCLUSIONS: The simple product of mean arterial pressure and peak aortic flow (simplified peak power, SPP) correlates with peak instantaneous power over a range of loading conditions in dogs. In humans, it can be estimated during exercise echocardiography, and correlates with maximum oxygen uptake better than ejection fraction or rate-pressure product.

Network, system, and status software enhancements for the autonomously managed electrical power system breadboard. Volume 2: Protocol specification

NASA Technical Reports Server (NTRS)

Mckee, James W.

1990-01-01

This volume (2 of 4) contains the specification, structured flow charts, and code listing for the protocol. The purpose of an autonomous power system on a spacecraft is to relieve humans from having to continuously monitor and control the generation, storage, and distribution of power in the craft. This implies that algorithms will have been developed to monitor and control the power system. The power system will contain computers on which the algorithms run. There should be one control computer system that makes the high level decisions and sends commands to and receive data from the other distributed computers. This will require a communications network and an efficient protocol by which the computers will communicate. One of the major requirements on the protocol is that it be real time because of the need to control the power elements.

Regulation of Dynamical Systems to Optimal Solutions of Semidefinite Programs: Algorithms and Applications to AC Optimal Power Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Dhople, Sairaj V.; Giannakis, Georgios B.

2015-07-01

This paper considers a collection of networked nonlinear dynamical systems, and addresses the synthesis of feedback controllers that seek optimal operating points corresponding to the solution of pertinent network-wide optimization problems. Particular emphasis is placed on the solution of semidefinite programs (SDPs). The design of the feedback controller is grounded on a dual e-subgradient approach, with the dual iterates utilized to dynamically update the dynamical-system reference signals. Global convergence is guaranteed for diminishing stepsize rules, even when the reference inputs are updated at a faster rate than the dynamical-system settling time. The application of the proposed framework to the controlmore » of power-electronic inverters in AC distribution systems is discussed. The objective is to bridge the time-scale separation between real-time inverter control and network-wide optimization. Optimization objectives assume the form of SDP relaxations of prototypical AC optimal power flow problems.« less

Power system characteristics for more electric aircraft

NASA Technical Reports Server (NTRS)

Hansen, Irving G.

1993-01-01

It should not be suprising that more electric aircraft must meet significantly more difficult electrical power system requirements than were considereed when today's power distribution systems were being developed. Electric power, no longer a secondary system, will become a critical element of the primary control system. Functional reliability requiirements will be extremely stringent and can only be met by controlling element redundancy within a distributed power system. Existing electrical systems were not developed to have both the power system and the control/sensing elements distributed and yet meet the requirements of lighting tolerance and high intensity radio frequency (HIRF). In addition, the operation of electric actuators involves high transient loading and reverse energy flows. Such phenomena were also not anticipated when power quality was specified for either 270 vdc or 400 Hertz ac power systems. This paper will expand upon the issues and discuss some of the technologies involved in their resolution.

Large-eddy simulation of flow in a plane, asymmetric diffuser

NASA Technical Reports Server (NTRS)

Kaltenbach, Hans-Jakob

1993-01-01

Recent improvements in subgrid-scale modeling as well as increases in computer power make it feasible to investigate flows using large-eddy simulation (LES) which have been traditionally studied with techniques based on Reynolds averaging. However, LES has not yet been applied to many flows of immediate technical interest. Preliminary results from LES of a plane diffuser flow are described. The long term goal of this work is to investigate flow separation as well as separation control in ducts and ramp-like geometries.

Application of voltage oriented control technique in a fully renewable, wind powered, autonomous system with storage capabilities

NASA Astrophysics Data System (ADS)

Kondylis, Georgios P.; Vokas, Georgios A.; Anastasiadis, Anestis G.; Konstantinopoulos, Stavros A.

2017-02-01

The main purpose of this paper is to examine the technological feasibility of a small autonomous network, with electricity storage capability, which is completely electrified by wind energy. The excess energy produced, with respect to the load requirements, is sent to the batteries for storage. When the energy produced by the wind generator is not sufficient, load's energy requirement is covered by the battery system, ensuring, however, that voltage, frequency and other system characteristics are within the proper boundaries. For the purpose of this study, a Voltage Oriented Control system has been developed in order to monitor the autonomous operation and perform the energy management of the network. This system manages the power flows between the load and the storage system by properly controlling the Pulse Width Modulation pulses in the converter, thus ensuring power flows are adequate and frequency remains under control. The experimental results clearly indicate that a stand-alone wind energy system based on battery energy storage system is feasible and reliable. This paves the way for fully renewable and zero emission energy schemes.

Computing Optic Flow with ArduEye Vision Sensor

DTIC Science & Technology

2013-01-01

processing algorithm that can be applied to the flight control of other robotic platforms. 15. SUBJECT TERMS Optical flow, ArduEye, vision based ...2 Figure 2. ArduEye vision chip on Stonyman breakout board connected to Arduino Mega (8) (left) and the Stonyman vision chips (7...robotic platforms. There is a significant need for small, light , less power-hungry sensors and sensory data processing algorithms in order to control the

Modification of the continuous flow diffusion chamber for use in zero-gravity. [atmospheric cloud physics lab

NASA Technical Reports Server (NTRS)

Keyser, G.

1978-01-01

The design philosophy and performance characteristics of the continuous flow diffusion chamber developed for use in ground-based simulation of some of the experiments planned for the atmospheric cloud physics laboratory during the first Spacelab flight are discussed. Topics covered include principle of operation, thermal control, temperature measurement, tem-powered heat exchangers, wettable metal surfaces, sample injection system, and control electronics.

Operational Characteristics of an Ultra Compact Combustor

DTIC Science & Technology

2014-03-27

to control this temperature profile to the turbine. A thermally non -uniform flow can create problems with power extraction and heat loading within...NOx) in an experimental rig set-up using air jet cross flows in non -reacting and reacting conditions at high pressure. NOx formation has become the...performance. One of the obstacles for implementing an UCC is the ability to control this temperature profile to the turbine. A thermally non

The minimum control authority of a system of actuators with applications to Gravity Probe-B

NASA Technical Reports Server (NTRS)

Wiktor, Peter; Debra, Dan

1991-01-01

The forcing capabilities of systems composed of many actuators are analyzed in this paper. Multiactuator systems can generate higher forces in some directions than in others. Techniques are developed to find the force in the weakest direction. This corresponds to the worst-case output and is defined as the 'minimum control authority'. The minimum control authority is a function of three things: the actuator configuration, the actuator controller and the way in which the output of the system is limited. Three output limits are studied: (1) fuel-flow rate, (2) power, and (3) actuator output. The three corresponding actuator controllers are derived. These controllers generate the desired force while minimizing either fuel flow rate, power or actuator output. It is shown that using the optimal controller can substantially increase the minimum control authority. The techniques for calculating the minimum control authority are applied to the Gravity Probe-B spacecraft thruster system. This example shows that the minimum control authority can be used to design the individual actuators, choose actuator configuration, actuator controller, and study redundancy.

Reliable and Affordable Control Systems Active Combustor Pattern Factor Control

NASA Technical Reports Server (NTRS)

McCarty, Bob; Tomondi, Chris; McGinley, Ray

2004-01-01

Active, closed-loop control of combustor pattern factor is a cooperative effort between Honeywell (formerly AlliedSignal) Engines and Systems and the NASA Glenn Research Center to reduce emissions and turbine-stator vane temperature variations, thereby enhancing engine performance and life, and reducing direct operating costs. Total fuel flow supplied to the engine is established by the speed/power control, but the distribution to individual atomizers will be controlled by the Active Combustor Pattern Factor Control (ACPFC). This system consist of three major components: multiple, thin-film sensors located on the turbine-stator vanes; fuel-flow modulators for individual atomizers; and control logic and algorithms within the electronic control.

Inverting Quasi-Resonant Switched-Capacitor Bidirectional Converter and Its Application to Battery Equalization

NASA Astrophysics Data System (ADS)

Lee, Yuang-Shung; Chiu, Yin-Yuan; Cheng, Ming-Wang; Ko, Yi-Pin; Hsiao, Sung-Hsin

The proposed quasi-resonant (QR) zero current switching (ZCS) switched-capacitor (SC) converter is a new type of bidirectional power flow control conversion scheme. The proposed converter is able to provide voltage conversion ratios from -3/-{1 \\over 3} (triple-mode/trisection-mode) to -n/-{1 \\over n} (-n-mode/-{1 \\over n}-mode) by adding a different number of switched-capacitors and power MOSFET switches with a small series connected resonant inductor for forward and reverse power flow control schemes. It possesses the advantages of low switching losses and current stress in this QR ZCS SC converter. The principle of operation, theoretical analysis of the proposed triple-mode/trisection-mode bidirectional power conversion scheme is described in detail with circuit model analysis. Simulation and experimental studies are carried out to verify the performance of the proposed inverting type ZCS SC QR bidirectional converter. The proposed converters can be applied to battery equalization for battery management system (BMS).

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

NASA Technical Reports Server (NTRS)

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.

Real time closed loop control of an Ar and Ar/O2 plasma in an ICP

NASA Astrophysics Data System (ADS)

Faulkner, R.; Soberón, F.; McCarter, A.; Gahan, D.; Karkari, S.; Milosavljevic, V.; Hayden, C.; Islyaikin, A.; Law, V. J.; Hopkins, M. B.; Keville, B.; Iordanov, P.; Doherty, S.; Ringwood, J. V.

2006-10-01

Real time closed loop control for plasma assisted semiconductor manufacturing has been the subject of academic research for over a decade. However, due to process complexity and the lack of suitable real time metrology, progress has been elusive and genuine real time, multi-input, multi-output (MIMO) control of a plasma assisted process has yet to be successfully implemented in an industrial setting. A Splasma parameter control strategy T is required to be adopted whereby process recipes which are defined in terms of plasma properties such as critical species densities as opposed to input variables such as rf power and gas flow rates may be transferable between different chamber types. While PIC simulations and multidimensional fluid models have contributed considerably to the basic understanding of plasmas and the design of process equipment, such models require a large amount of processing time and are hence unsuitable for testing control algorithms. In contrast, linear dynamical empirical models, obtained through system identification techniques are ideal in some respects for control design since their computational requirements are comparatively small and their structure facilitates the application of classical control design techniques. However, such models provide little process insight and are specific to an operating point of a particular machine. An ideal first principles-based, control-oriented model would exhibit the simplicity and computational requirements of an empirical model and, in addition, despite sacrificing first principles detail, capture enough of the essential physics and chemistry of the process in order to provide reasonably accurate qualitative predictions. This paper will discuss the development of such a first-principles based, control-oriented model of a laboratory inductively coupled plasma chamber. The model consists of a global model of the chemical kinetics coupled to an analytical model of power deposition. Dynamics of actuators including mass flow controllers and exhaust throttle are included and sensor characteristics are also modelled. The application of this control-oriented model to achieve multivariable closed loop control of specific species e.g. atomic Oxygen and ion density using the actuators rf power, Oxygen and Argon flow rates, and pressure/exhaust flow rate in an Ar/O2 ICP plasma will be presented.

Self-actuating reactor shutdown system

DOEpatents

Barrus, Donald M.; Brummond, Willian A; Peterson, Leslie F.

1988-01-01

A control system for the automatic or self-actuated shutdown or "scram" of a nuclear reactor. The system is capable of initiating scram insertion by a signal from the plant protection system or by independent action directly sensing reactor conditions of low-flow or over-power. Self-actuation due to a loss of reactor coolant flow results from a decrease of pressure differential between the upper and lower ends of an absorber element. When the force due to this differential falls below the weight of the element, the element will fall by gravitational force to scram the reactor. Self-actuation due to high neutron flux is accomplished via a valve controlled by an electromagnet and a thermionic diode. In a reactor over-power, the diode will be heated to a change of state causing the electromagnet to be shorted thereby actuating the valve which provides the changed flow and pressure conditions required for scramming the absorber element.

Grid tied PV/battery system architecture and power management for fast electric vehicle charging

NASA Astrophysics Data System (ADS)

Badawy, Mohamed O.

The prospective spread of Electric vehicles (EV) and plug-in hybrid electric vehicles (PHEV) arises the need for fast charging rates. Higher charging rates requirements lead to high power demands, which cant be always supported by the grid. Thus, the use of on-site sources alongside the electrical grid for EVs charging is a rising area of interest. In this dissertation, a photovoltaic (PV) source is used to support the high power EVs charging. However, the PV output power has an intermittent nature that is dependable on the weather conditions. Thus, battery storage are combined with the PV in a grid tied system, providing a steady source for on-site EVs use in a renewable energy based fast charging station. Verily, renewable energy based fast charging stations should be cost effective, efficient, and reliable to increase the penetration of EVs in the automotive market. Thus, this Dissertation proposes a novel power flow management topology that aims on decreasing the running cost along with innovative hardware solutions and control structures for the developed architecture. The developed power flow management topology operates the hybrid system at the minimum operating cost while extending the battery lifetime. An optimization problem is formulated and two stages of optimization, i.e online and offline stages, are adopted to optimize the batteries state of charge (SOC) scheduling and continuously compensate for the forecasting errors. The proposed power flow management topology is validated and tested with two metering systems, i.e unified and dual metering systems. The results suggested that minimal power flow is anticipated from the battery storage to the grid in the dual metering system. Thus, the power electronic interfacing system is designed accordingly. Interconnecting bi-directional DC/DC converters are analyzed, and a cascaded buck boost (CBB) converter is chosen and tested under 80 kW power flow rates. The need to perform power factor correction (PFC) on the grid power while supplying the battery storage and the DC loads inspired a novel dual switch control structure for the CBB AC/DC converter used in this dissertation. Thus, The CBB operates at a discontinuous capacitor voltage mode (DCVM) and the control structure enables for a non-distorted input current at overlapping output voltage levels. The PFC concept is validated and tested for a single phase rectifier and a 3 phase extension of the proposed concept is presented. Lastly, the PV source used in this study is required to supply power to both, the grid system, and to the DC loads, i.e the battery storage and the EVs. Thus, the PV panels used are connected in series to reach a desirable high voltage on the DC bus output of the PV system. Consequently, a novel differential power processing architecture is proposed in this dissertation. The proposed architecture enables each PV element to operate at its local maximum power point (MPP) while processing only a small portion of its total generated power through the distributed integrated converters. This leads to higher energy capture at an increased conversion efficiency while overcoming the difficulties associated with unmatched MPPs of the PV elements.

Self-regulating flow control device

DOEpatents

Humphreys, Duane A.

1984-01-01

A variable, self-regulating valve having a hydraulic loss coefficient proportional to a positive exponential power of the flow rate. The device includes two objects in a flow channel and structure which assures that the distance between the two objects is an increasing function of the flow rate. The range of spacing between the objects is such that the hydraulic resistance of the valve is an increasing function of the distance between the two objects so that the desired hydraulic loss coefficient as a function of flow rate is obtained without variation in the flow area.

Energy harvesting for self-powered aerostructure actuation

NASA Astrophysics Data System (ADS)

Bryant, Matthew; Pizzonia, Matthew; Mehallow, Michael; Garcia, Ephrahim

2014-04-01

This paper proposes and experimentally investigates applying piezoelectric energy harvesting devices driven by flow induced vibrations to create self-powered actuation of aerostructure surfaces such as tabs, flaps, spoilers, or morphing devices. Recently, we have investigated flow-induced vibrations and limit cycle oscillations due to aeroelastic flutter phenomena in piezoelectric structures as a mechanism to harvest energy from an ambient fluid flow. We will describe how our experimental investigations in a wind tunnel have demonstrated that this harvested energy can be stored and used on-demand to actuate a control surface such as a trailing edge flap in the airflow. This actuated control surface could take the form of a separate and discrete actuated flap, or could constitute rotating or deflecting the oscillating energy harvester itself to produce a non-zero mean angle of attack. Such a rotation of the energy harvester and the associated change in aerodynamic force is shown to influence the operating wind speed range of the device, its limit cycle oscillation (LCO) amplitude, and its harvested power output; hence creating a coupling between the device's performance as an energy harvester and as a control surface. Finally, the induced changes in the lift, pitching moment, and drag acting on a wing model are quantified and compared for a control surface equipped with an oscillating energy harvester and a traditional, static control surface of the same geometry. The results show that when operated in small amplitude LCO the energy harvester adds negligible aerodynamic drag.

Unscheduled load flow effect due to large variation in the distributed generation in a subtransmission network

NASA Astrophysics Data System (ADS)

Islam, Mujahidul

A sustainable energy delivery infrastructure implies the safe and reliable accommodation of large scale penetration of renewable sources in the power grid. In this dissertation it is assumed there will be no significant change in the power transmission and distribution structure currently in place; except in the operating strategy and regulatory policy. That is to say, with the same old structure, the path towards unveiling a high penetration of switching power converters in the power system will be challenging. Some of the dimensions of this challenge are power quality degradation, frequent false trips due to power system imbalance, and losses due to a large neutral current. The ultimate result is the reduced life of many power distribution components - transformers, switches and sophisticated loads. Numerous ancillary services are being developed and offered by the utility operators to mitigate these problems. These services will likely raise the system's operational cost, not only from the utility operators' end, but also reflected on the Independent System Operators and by the Regional Transmission Operators (RTO) due to an unforeseen backlash of frequent variation in the load-side generation or distributed generation. The North American transmission grid is an interconnected system similar to a large electrical circuit. This circuit was not planned but designed over 100 years. The natural laws of physics govern the power flow among loads and generators except where control mechanisms are installed. The control mechanism has not matured enough to withstand the high penetration of variable generators at uncontrolled distribution ends. Unlike a radial distribution system, mesh or loop networks can alleviate complex channels for real and reactive power flow. Significant variation in real power injection and absorption on the distribution side can emerge as a bias signal on the routing reactive power in some physical links or channels that are not distinguishable from the vast network. A path tracing methodology is developed to identify the power lines that are vulnerable to an unscheduled flow effect in the sub-transmission network. It is much harder to aggregate power system network sensitivity information or data from measuring load flow physically than to simulate in software. System dynamics is one of the key factors to determine an appropriate dynamic control mechanism at an optimum network location. Once a model of deterministic but variable power generator is used, the simulation can be meaningful in justifying this claim. The method used to model the variable generator is named the two-components phase distortion model. The model was validated from the high resolution data collected from three pilot photovoltaic sites in Florida - two in the city of St. Petersburg and one in the city of Tampa. The high resolution data was correlated with weather radar closest to the sites during the design stage of the model. Technically the deterministic model cannot replicate a stochastic model which is more realistically applicable for solar isolation and involves a Markov chain. The author justified the proposition based on the fact that for analysis of the response functions of different systems, the excitation function should be common for comparison. Moreover, there could be many possible simulation scenarios but fewer worst cases. Almost all commercial systems are protected against potential faults and contingencies to a certain extent. Hence, the proposed model for worst case studies was designed within a reasonable limit. The simulation includes steady state and transient mode using multiple software modules including MatlabRTM, PSCADRTM and Paladin Design BaseRTM. It is shown that by identifying vulnerable or sensitive branches in the network, the control mechanisms can be coordinated reliably. In the long run this can save money by preventing unscheduled power flow in the network and eventually stabilizing the energy market.

Performance Evaluation of UPQC under Nonlinear Unbalanced Load Conditions Using Synchronous Reference Frame Based Control

NASA Astrophysics Data System (ADS)

Kota, Venkata Reddy; Vinnakoti, Sudheer

2017-12-01

Today, maintaining Power Quality (PQ) is very important in the growing competent world. With new equipments and devices, new challenges are also being put before power system operators. Unified Power Quality Conditioner (UPQC) is proposed to mitigate many power quality problems and to improve the performance of the power system. In this paper, an UPQC with Fuzzy Logic controller for capacitor voltage balancing is proposed in Synchronous Reference Frame (SRF) based control with Modified Phased Locked Loop (MPLL). The proposed controller with SRF-MPLL based control is tested under non-linear and unbalanced load conditions. The system is developed in Matlab/Simulink and its performance is analyzed under various conditions like non-linear, unbalanced load and polluted supply voltage including voltage sag/swells. Active and reactive power flow in the system, power factor and %THD of voltages and currents before and after compensation are also analyzed in this work. Results prove the applicability of the proposed scheme for power quality improvement. It is observed that the fuzzy controller gives better performance than PI controller with faster capacitor voltage balancing and also improves the dynamic performance of the system.

Variable-pulse switching circuit accurately controls solenoid-valve actuations

NASA Technical Reports Server (NTRS)

Gillett, J. D.

1967-01-01

Solid state circuit generating adjustable square wave pulses of sufficient power operates a 28 volt dc solenoid valve at precise time intervals. This circuit is used for precise time control of fluid flow in combustion experiments.

Advanced Energy Harvesting Control Schemes for Marine Renewable Energy Devices

DOE Office of Scientific and Technical Information (OSTI.GOV)

McEntee, Jarlath; Polagye, Brian; Fabien, Brian

2016-03-31

The Advanced Energy Harvesting Control Schemes for Marine Renewable Energy Devices (Project) investigated, analyzed and modeled advanced turbine control schemes with the objective of increasing the energy harvested by hydrokinetic turbines in turbulent flow. Ocean Renewable Power Company (ORPC) implemented and validated a feedforward controller to increase power capture; and applied and tested the controls on ORPC’s RivGen® Power Systems in Igiugig, Alaska. Assessments of performance improvements were made for the RivGen® in the Igiugig environment and for ORPC’s TidGen® Power System in a reference tidal environment. Annualized Energy Production (AEP) and Levelized Cost of Energy (LCOE) improvements associated withmore » implementation of the recommended control methodology were made for the TidGen® Power System in the DOE reference tidal environment. System Performance Advancement (SPA) goals were selected for the project. SPA targets were to improve Power to Weight Ratio (PWR) and system Availability, with the intention of reducing Levelized Cost of Electricity (LCOE). This project focused primarily reducing in PWR. Reductions in PWR of 25.5% were achieved. Reductions of 20.3% in LCOE were achieved. This project evaluated four types of controllers which were tested in simulation, emulation, a laboratory flume, and the field. The adaptive Kω2 controller performs similarly to the non-adaptive version of the same controller and may be useful in tidal channels where the mean velocity is continually evolving. Trends in simulation were largely verified through experiments, which also provided the opportunity to test assumptions about turbine responsiveness and control resilience to varying scales of turbulence. Laboratory experiments provided an essential stepping stone between simulation and implementation on a field-scale turbine. Experiments also demonstrated that using “energy loss” as a metric to differentiate between well-designed controllers operating at an optimal tip-speed ratio set-point is difficult, which anticipated the outcome from field experiments. The clear message is that the feedforward Kω2 controller out-performs the feedback controllers in almost all aspects and modes of evaluation. The controllers proved a substantial improvement over the baseline performance of the TidGen® turbine, in terms of energy capture. The effects of noise-contaminated angular velocity signals were investigated and validated by simulation as an explanation for the performance limitations observed for TidGen® turbine operations in Eastport, Maine. Measurements of loads performed as part of the laboratory testing indicate that there are limited differences in average axial thrust force between control architectures. This suggests that none of the control strategies are likely to substantially affect loads on the turbine support structure. Velocity measurements during the ORPC RivGen® turbine deployment at Igiugig, Alaska, in 2014 were used to assess the variability of the river flow. Results suggest that the river flow is approximately steady, in the mean sense, at any particular location in the river, with random turbulent fluctuations that are around 10% of the mean flow. The mean flow in the center channel of the river is 2.5 m/s, with reductions near the riverbanks and in the shallows. Spectral analysis and lagged correlation results indicate that temporal fluctuations at a given point are dominated by large scale fluctuations, such that measurements at the turbine location are just as useful for inflow control implementation as upstream measurements. At this site, and likely at many other river sites, flow is generally steady at a given location, but flow varies dramatically between locations, particularly laterally across the river. The primary result is that a lateral change in position of a few meters results in changes to flow speed that far exceed the turbulence fluctuations at any given location. The turbulence is dominated by long time scales. Following final system tests, the RivGen® device was submerged and each evaluated controller was tested across a range of gain/set point values and filter configurations for a minimum of 5 minutes, with longer runs attempted for well-performing cases. In addition to testing controllers during the 2015 deployment season, LGL Alaska Research Associates Inc. (LGL) performed a fish monitoring study in compliance with Alaska Department of Fish and Game fisheries habitat permit for the project. During the season, LGL reviewed 10% of 179 one-hour blocks of footage (6 minutes on the hour) and documented a total of over 1200 fish in the vicinity of the RivGen® device, including over 800 salmon smolt and over 350 adult salmon. No evidence of adverse effects including passage delay by upstream migrating salmon was noted. This is an important result for future deployments and has a direct impact on commercial system designs.« less

ZaP-HD: High Energy Density Z-Pinch Plasmas using Sheared Flow Stabilization

NASA Astrophysics Data System (ADS)

Golingo, R. P.; Shumlak, U.; Nelson, B. A.; Claveau, E. L.; Doty, S. A.; Forbes, E. G.; Hughes, M. C.; Kim, B.; Ross, M. P.; Weed, J. R.

2015-11-01

The ZaP-HD flow Z-pinch project investigates scaling the flow Z-pinch to High Energy Density Plasma, HEDP, conditions by using sheared flow stabilization. ZaP used a single power supply to produce 100 cm long Z-pinches that were quiescent for many radial Alfven times and axial flow-through times. The flow Z-pinch concept provides an approach to achieve HED plasmas, which are dimensionally large and persist for extended durations. The ZaP-HD device replaces the single power supply from ZaP with two separate power supplies to independently control the plasma flow and current in the Z-pinch. Equilibrium is determined by diagnostic measurements of the density with interferometry and digital holography, the plasma flow and temperature with passive spectroscopy, the magnetic field with surface magnetic probes, and plasma emission with optical imaging. The diagnostics fully characterize the plasma from its initiation in the coaxial accelerator, through the pinch, and exhaust from the assembly region. The plasma evolution is modeled with high resolution codes: Mach2, WARPX, and NIMROD. Experimental results and scaling analyses are presented. This work is supported by grants from the U.S. Department of Energy and the U.S. National Nuclear Security Administration.

Generator powered electrically heated diesel particulate filter

DOEpatents

Gonze, Eugene V; Paratore, Jr., Michael J

2014-03-18

A control circuit for a vehicle powertrain includes a switch that selectivity interrupts current flow between a first terminal and a second terminal. A first power source provides power to the first terminal and a second power source provides power to the second terminal and to a heater of a heated diesel particulate filter (DPF). The switch is opened during a DPF regeneration cycle to prevent the first power source from being loaded by the heater while the heater is energized.

Optimal placement of unified power flow controllers to improve dynamic voltage stability using power system variable based voltage stability indices.

PubMed

Albatsh, Fadi M; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M A

2015-01-01

This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches.

Optimal Placement of Unified Power Flow Controllers to Improve Dynamic Voltage Stability Using Power System Variable Based Voltage Stability Indices

PubMed Central

Albatsh, Fadi M.; Ahmad, Shameem; Mekhilef, Saad; Mokhlis, Hazlie; Hassan, M. A.

2015-01-01

This study examines a new approach to selecting the locations of unified power flow controllers (UPFCs) in power system networks based on a dynamic analysis of voltage stability. Power system voltage stability indices (VSIs) including the line stability index (LQP), the voltage collapse proximity indicator (VCPI), and the line stability index (Lmn) are employed to identify the most suitable locations in the system for UPFCs. In this study, the locations of the UPFCs are identified by dynamically varying the loads across all of the load buses to represent actual power system conditions. Simulations were conducted in a power system computer-aided design (PSCAD) software using the IEEE 14-bus and 39- bus benchmark power system models. The simulation results demonstrate the effectiveness of the proposed method. When the UPFCs are placed in the locations obtained with the new approach, the voltage stability improves. A comparison of the steady-state VSIs resulting from the UPFCs placed in the locations obtained with the new approach and with particle swarm optimization (PSO) and differential evolution (DE), which are static methods, is presented. In all cases, the UPFC locations given by the proposed approach result in better voltage stability than those obtained with the other approaches. PMID:25874560

Helicopter Fuselage Active Flow Control in the Presence of a Rotor

NASA Technical Reports Server (NTRS)

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.

Optically triggered high voltage switch network and method for switching a high voltage

DOEpatents

El-Sharkawi, Mohamed A.; Andexler, George; Silberkleit, Lee I.

1993-01-19

An optically triggered solid state switch and method for switching a high voltage electrical current. A plurality of solid state switches (350) are connected in series for controlling electrical current flow between a compensation capacitor (112) and ground in a reactive power compensator (50, 50') that monitors the voltage and current flowing through each of three distribution lines (52a, 52b and 52c), which are supplying three-phase power to one or more inductive loads. An optical transmitter (100) controlled by the reactive power compensation system produces light pulses that are conveyed over optical fibers (102) to a switch driver (110') that includes a plurality of series connected optical triger circuits (288). Each of the optical trigger circuits controls a pair of the solid state switches and includes a plurality of series connected resistors (294, 326, 330, and 334) that equalize or balance the potential across the plurality of trigger circuits. The trigger circuits are connected to one of the distribution lines through a trigger capacitor (340). In each switch driver, the light signals activate a phototransistor (300) so that an electrical current flows from one of the energy reservoir capacitors through a pulse transformer (306) in the trigger circuit, producing gate signals that turn on the pair of serially connected solid state switches (350).

Membrane has high urea-rejection properties

NASA Technical Reports Server (NTRS)

Johnson, C. C.; Wydeven, T.

1977-01-01

Membranes are synthesized from ethylene and nitrogen in RF plasma at low power, gas-flow rates, and pressure. Ethylene and nitrogen are used because flow rate and partial pressure of each gas can be independently controlled to produce optimum conditions for synthesizing membrane. Membrane is particularly useful in recycling and purifying water.

Thermoelectric power generator for variable thermal power source

DOEpatents

Bell, Lon E; Crane, Douglas Todd

2015-04-14

Traditional power generation systems using thermoelectric power generators are designed to operate most efficiently for a single operating condition. The present invention provides a power generation system in which the characteristics of the thermoelectrics, the flow of the thermal power, and the operational characteristics of the power generator are monitored and controlled such that higher operation efficiencies and/or higher output powers can be maintained with variably thermal power input. Such a system is particularly beneficial in variable thermal power source systems, such as recovering power from the waste heat generated in the exhaust of combustion engines.

Optimal Power Flow for Distribution Systems under Uncertain Forecasts: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Baker, Kyri; Summers, Tyler

2016-12-01

The paper focuses on distribution systems featuring renewable energy sources and energy storage devices, and develops an optimal power flow (OPF) approach to optimize the system operation in spite of forecasting errors. The proposed method builds on a chance-constrained multi-period AC OPF formulation, where probabilistic constraints are utilized to enforce voltage regulation with a prescribed probability. To enable a computationally affordable solution approach, a convex reformulation of the OPF task is obtained by resorting to i) pertinent linear approximations of the power flow equations, and ii) convex approximations of the chance constraints. Particularly, the approximate chance constraints provide conservative boundsmore » that hold for arbitrary distributions of the forecasting errors. An adaptive optimization strategy is then obtained by embedding the proposed OPF task into a model predictive control framework.« less

Motor Starters

NASA Technical Reports Server (NTRS)

1986-01-01

The power factor controller (PFC) was invented by a NASA engineer. It matches voltage with a motor's actual need by sensing shifts in the relationship between voltage and current flow. With the device, power can be trimmed as much as 65%. Intellinet adopted this technology and designed "soft start" and "load-responsive" control modes to start engines gradually and recycle voltage without reducing motor speed. Other features are lower motor heat and faster fault identification.

Full State Feedback Control for Virtual Power Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Jay Tillay

This report presents an object-oriented implementation of full state feedback control for virtual power plants (VPP). The components of the VPP full state feedback control are (1) objectoriented high-fidelity modeling for all devices in the VPP; (2) Distribution System Distributed Quasi-Dynamic State Estimation (DS-DQSE) that enables full observability of the VPP by augmenting actual measurements with virtual, derived and pseudo measurements and performing the Quasi-Dynamic State Estimation (QSE) in a distributed manner, and (3) automated formulation of the Optimal Power Flow (OPF) in real time using the output of the DS-DQSE, and solving the distributed OPF to provide the optimalmore » control commands to the DERs of the VPP.« less

Distributed Optimal Power Flow of AC/DC Interconnected Power Grid Using Synchronous ADMM

NASA Astrophysics Data System (ADS)

Liang, Zijun; Lin, Shunjiang; Liu, Mingbo

2017-05-01

Distributed optimal power flow (OPF) is of great importance and challenge to AC/DC interconnected power grid with different dispatching centres, considering the security and privacy of information transmission. In this paper, a fully distributed algorithm for OPF problem of AC/DC interconnected power grid called synchronous ADMM is proposed, and it requires no form of central controller. The algorithm is based on the fundamental alternating direction multiplier method (ADMM), by using the average value of boundary variables of adjacent regions obtained from current iteration as the reference values of both regions for next iteration, which realizes the parallel computation among different regions. The algorithm is tested with the IEEE 11-bus AC/DC interconnected power grid, and by comparing the results with centralized algorithm, we find it nearly no differences, and its correctness and effectiveness can be validated.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, John M.; Onar, Omer C.; Chinthavali, Madhu

Various noncontacting methods of plug-in electric vehicle charging are either under development or now deployed as aftermarket options in the light-duty automotive market. Wireless power transfer (WPT) is now the accepted term for wireless charging and is used synonymously for inductive power transfer and magnetic resonance coupling. WPT technology is in its infancy; standardization is lacking, especially on interoperability, center frequency selection, magnetic fringe field suppression, and the methods employed for power flow regulation. This paper proposes a new analysis concept for power flow in WPT in which the primary provides frequency selection and the tuned secondary, with its resemblancemore » to a power transmission network having a reactive power voltage control, is analyzed as a transmission network. Analysis is supported with experimental data taken from Oak Ridge National Laboratory s WPT apparatus. Lastly, this paper also provides an experimental evidence for frequency selection, fringe field assessment, and the need for low-latency communications in the feedback path.« less

Method and apparatus for in-cell vacuuming of radiologically contaminated materials

DOEpatents

Spadaro, Peter R.; Smith, Jay E.; Speer, Elmer L.; Cecconi, Arnold L.

1987-01-01

A vacuum air flow operated cyclone separator arrangement for collecting, handling and packaging loose contaminated material in accordance with acceptable radiological and criticality control requirements. The vacuum air flow system includes a specially designed fail-safe prefilter installed upstream of the vacuum air flow power supply. The fail-safe prefilter provides in-cell vacuum system flow visualization and automatically reduces or shuts off the vacuum air flow in the event of an upstream prefilter failure. The system is effective for collecting and handling highly contaminated radiological waste in the form of dust, dirt, fuel element fines, metal chips and similar loose material in accordance with radiological and criticality control requirements for disposal by means of shipment and burial.

Development of a smart type motor operated valve for nuclear power plants

NASA Astrophysics Data System (ADS)

Kim, Chang-Hwoi; Park, Joo-Hyun; Lee, Dong-young; Koo, In-Soo

2005-12-01

In this paper, the design concept of the smart type motor operator valve for nuclear power plant was described. The development objective of the smart valve is to achieve superior accuracy, long-term reliability, and ease of use. In this reasons, developed smart valve has fieldbus communication such as deviceNet and Profibus-DP, auto-tuning PID controller, self-diagnostics, and on-line calibration capabilities. And also, to achieve pressure, temperature, and flow control with internal PID controller, the pressure sensor and transmitter were included in this valve. And, temperature and flow signal acquisition port was prepared. The developed smart valve will be performed equipment qualification test such as environment, EMI/EMC, and vibration in Korea Test Lab. And, the valve performance is tested in a test loop which is located in Seoul National University Lab. To apply nuclear power plant, the software is being developed according to software life cycle. The developed software is verified by independent software V and V team. It is expected that the smart valve can be applied to an existing NPPs for replacing or to a new nuclear power plants. The design and fabrication of smart valve is now being processed.

Jet spoiler arrangement for wind turbine

DOEpatents

Cyrus, J.D.; Kadlec, E.G.; Klimas, P.C.

1983-09-15

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Jet spoiler arrangement for wind turbine

DOEpatents

Cyrus, Jack D.; Kadlec, Emil G.; Klimas, Paul C.

1985-01-01

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the ends thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby inducing stall conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Jet spoiler arrangement for wind turbine

NASA Astrophysics Data System (ADS)

Cyrus, J. D.; Kablec, E. G.; Klimas, P. C.

1983-09-01

An air jet spoiler arrangement is provided for a Darrieus-type vertical axis wind-powered turbine. Air is drawn into hollow turbine blades through air inlets at the end thereof and is ejected in the form of air jets through small holes or openings provided along the lengths of the blades. The air jets create flow separation at the surfaces of the turbine blades, thereby including stal conditions and reducing the output power. A feedback control unit senses the power output of the turbine and controls the amount of air drawn into the air inlets accordingly.

Design of a stateless low-latency router architecture for green software-defined networking

NASA Astrophysics Data System (ADS)

Saldaña Cercós, Silvia; Ramos, Ramon M.; Ewald Eller, Ana C.; Martinello, Magnos; Ribeiro, Moisés. R. N.; Manolova Fagertun, Anna; Tafur Monroy, Idelfonso

2015-01-01

Expanding software defined networking (SDN) to transport networks requires new strategies to deal with the large number of flows that future core networks will have to face. New south-bound protocols within SDN have been proposed to benefit from having control plane detached from the data plane offering a cost- and energy-efficient forwarding engine. This paper presents an overview of a new approach named KeyFlow to simultaneously reduce latency, jitter, and power consumption in core network nodes. Results on an emulation platform indicate that round trip time (RTT) can be reduced above 50% compared to the reference protocol OpenFlow, specially when flow tables are densely populated. Jitter reduction has been demonstrated experimentally on a NetFPGA-based platform, and 57.3% power consumption reduction has been achieved.

Apparatus for dispensing compressed natural gas and liquified natural gas to natural gas powered vehicles

DOEpatents

Bingham, Dennis A.; Clark, Michael L.; Wilding, Bruce M.; Palmer, Gary L.

2007-05-29

A fueling facility and method for dispensing liquid natural gas (LNG), compressed natural gas (CNG) or both on-demand. The fueling facility may include a source of LNG, such as cryogenic storage vessel. A low volume high pressure pump is coupled to the source of LNG to produce a stream of pressurized LNG. The stream of pressurized LNG may be selectively directed through an LNG flow path or to a CNG flow path which includes a vaporizer configured to produce CNG from the pressurized LNG. A portion of the CNG may be drawn from the CNG flow path and introduced into the CNG flow path to control the temperature of LNG flowing therethrough. Similarly, a portion of the LNG may be drawn from the LNG flow path and introduced into the CNG flow path to control the temperature of CNG flowing therethrough.

Method and apparatus for dispensing compressed natural gas and liquified natural gas to natural gas powered vehicles

DOEpatents

Bingham, Dennis A.; Clark, Michael L.; Wilding, Bruce M.; Palmer, Gary L.

2005-05-31

A fueling facility and method for dispensing liquid natural gas (LNG), compressed natural gas (CNG) or both on-demand. The fueling facility may include a source of LNG, such as cryogenic storage vessel. A low volume high pressure pump is coupled to the source of LNG to produce a stream of pressurized LNG. The stream of pressurized LNG may be selectively directed through an LNG flow path or to a CNG flow path which includes a vaporizer configured to produce CNG from the pressurized LNG. A portion of the CNG may be drawn from the CNG flow path and introduced into the CNG flow path to control the temperature of LNG flowing therethrough. Similarly, a portion of the LNG may be drawn from the LNG flow path and introduced into the CNG flow path to control the temperature of CNG flowing therethrough.

Experimental assessment of spanwise-oscillating dielectric electroactive surfaces for turbulent drag reduction in an air channel flow

NASA Astrophysics Data System (ADS)

Gatti, Davide; Güttler, Andreas; Frohnapfel, Bettina; Tropea, Cameron

2015-05-01

In the present work, wall oscillations for turbulent skin friction drag reduction are realized in an air turbulent duct flow by means of spanwise-oscillating active surfaces based on dielectric electroactive polymers. The actuator system produces spanwise wall velocity oscillations of 820 mm/s semi-amplitude at its resonance frequency of 65 Hz while consuming an active power of a few 100 mW. The actuators achieved a maximum integral drag reduction of 2.4 %. The maximum net power saving, budget of the power benefit and cost of the control, was measured for the first time with wall oscillations. Though negative, the net power saving is order of magnitudes higher than what has been estimated in previous studies. Two new direct numerical simulations of turbulent channel flow show that the finite size of the actuator only partially explains the lower values of integral drag reduction typically achieved in laboratory experiments compared to numerical simulations.

18 CFR 12.25 - Posting and readiness.

Code of Federal Regulations, 2010 CFR

2010-04-01

..., DEPARTMENT OF ENERGY REGULATIONS UNDER THE FEDERAL POWER ACT SAFETY OF WATER POWER PROJECTS AND PROJECT WORKS... personnel who are responsible for controlling water flows and for notifying public health and safety agencies and affected persons. (b) Each licensee or applicant must annually test the state of training and...

Effect of Several Factors on the Cooling of a Radial Engine in Flight

NASA Technical Reports Server (NTRS)

Schey, Oscar W; Pinkel, Benjamin

1936-01-01

Flight tests of a Grumman Scout (XSF-2) airplane fitted with a Pratt & Whitney 1535 supercharged engine were conducted to determine the effect of engine power, mass flow of the cooling air, and atmospheric temperature on cylinder temperature. The tests indicated that the difference in temperature between the cylinder wall and the cooling air varied as the 0.38 power of the brake horsepower for a constant mass flow of cooling air, cooling-air temperature, engine speed, and brake fuel consumption. The difference in temperature was also found to vary inversely as the 0.39 power of the mass flow for points on the head and the 0.35 power for points on the barrel, provided that engine power, engine speed, brake fuel consumption, and cooling-air temperature were kept constant. The results of the tests of the effect of atmospheric temperature on cylinder temperature were inconclusive owing to unfavorable weather conditions prevailing at the time of the tests. The method used for controlling the test conditions, however, was found to be feasible.

Unity power factor converter

NASA Technical Reports Server (NTRS)

Wester, Gene W. (Inventor)

1980-01-01

A unity power factor converter capable of effecting either inversion (dc-to-dc) or rectification (ac-to-dc), and capable of providing bilateral power control from a DC source (or load) through an AC transmission line to a DC load (or source) for power flow in either direction, is comprised of comparators for comparing the AC current i with an AC signal i.sub.ref (or its phase inversion) derived from the AC ports to generate control signals to operate a switch control circuit for high speed switching to shape the AC current waveform to a sine waveform, and synchronize it in phase and frequency with the AC voltage at the AC ports, by selectively switching the connections to a series inductor as required to increase or decrease the current i.

Performance of a Dynamically Controlled Inverter in a Photovoltaic System Interconnected with a Secondary Network Distribution System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coddington, M. H.; Kroposki, B. D.; Basso, T.

In 2008, a 300 kW{sub peak} photovoltaic (PV) system was installed on the rooftop of the Colorado Convention Center (CCC). The installation was unique for the electric utility, Xcel Energy, as it had not previously permitted a PV system to be interconnected on a building served by the local secondary network distribution system (network). The PV system was installed with several provisions; one to prevent reverse power flow, another called a dynamically controlled inverter (DCI), that curtails the output of the PV inverters to maintain an amount of load supplied by Xcel Energy at the CCC. The DCI system utilizesmore » current transformers (CTs) to sense power flow to insure that a minimum threshold is maintained from Xcel Energy through the network transformers. The inverters are set to track the load on each of the three phases and curtail power from the PV system when the generated PV system current reaches 95% of the current on any phase. This is achieved by the DCI, which gathers inputs from current transformers measuring the current from the PV array, Xcel, and the spot network load. Preventing reverse power flow is a critical technical requirement for the spot network which serve this part of the CCC. The PV system was designed with the expectation that the DCI system would not curtail the PV system, as the expected minimum load consumption was historically higher than the designed PV system size. However, the DCI system has operated many days during the course of a year, and the performance has been excellent. The DCI system at the CCC was installed as a secondary measure to insure that a minimum level of power flows to the CCC from the Xcel Energy network. While this DCI system was intended for localized control, the system could also reduce output percent if an external smart grid control signal was employed. This paper specifically focuses on the performance of the innovative design at this installation; however, the DCI system could also be used for new s- art grid-enabled distribution systems where renewables power contributions at certain conditions or times may need to be curtailed.« less

Flow profiling of a surface-acoustic-wave nanopump.

PubMed

Guttenberg, Z; Rathgeber, A; Keller, S; Rädler, J O; Wixforth, A; Kostur, M; Schindler, M; Talkner, P

2004-11-01

The flow profile in a capillary gap and the pumping efficiency of an acoustic micropump employing surface acoustic waves is investigated both experimentally and theoretically. Ultrasonic surface waves on a piezoelectric substrate strongly couple to a thin liquid layer and generate a quadrupolar streaming pattern within the fluid. We use fluorescence correlation spectroscopy and fluorescence microscopy as complementary tools to investigate the resulting flow profile. The velocity was found to depend on the applied power approximately linearly and to decrease with the inverse third power of the distance from the ultrasound generator on the chip. The found properties reveal acoustic streaming as a promising tool for the controlled agitation during microarray hybridization.

Flow profiling of a surface-acoustic-wave nanopump

NASA Astrophysics Data System (ADS)

Guttenberg, Z.; Rathgeber, A.; Keller, S.; Rädler, J. O.; Wixforth, A.; Kostur, M.; Schindler, M.; Talkner, P.

2004-11-01

The flow profile in a capillary gap and the pumping efficiency of an acoustic micropump employing surface acoustic waves is investigated both experimentally and theoretically. Ultrasonic surface waves on a piezoelectric substrate strongly couple to a thin liquid layer and generate a quadrupolar streaming pattern within the fluid. We use fluorescence correlation spectroscopy and fluorescence microscopy as complementary tools to investigate the resulting flow profile. The velocity was found to depend on the applied power approximately linearly and to decrease with the inverse third power of the distance from the ultrasound generator on the chip. The found properties reveal acoustic streaming as a promising tool for the controlled agitation during microarray hybridization.

Plasma-Assisted Control of Mach-2 Flowfield over Ramp Geometry

NASA Astrophysics Data System (ADS)

Watanabe, Yasumasa; Leonov, Sergey B.; Houpt, Alec; Hedlund, Brock E.; Elliott, Skye

2017-10-01

This study examined the effect of Reynolds number on plasma-assisted flow control ahead of a compression ramp geometry in Mach-2 supersonic flow. The experiments were conducted in the supersonic wind tunnel SBR-50 at the University of Notre Dame. Stagnation temperature and pressure were varied as T0=294-500K and P0=1-3bar to attain Reynolds number ranging from 3.4×105-2.2×106. Ramp pressure measurements, schlieren visualization, and high-speed camera imaging were used for the evaluation of plasma-assisted flow control effects. A linear dependency was found between the ramp pressure change per averaged plasma power and Reynolds number.

Controlling transient chaos in deterministic flows with applications to electrical power systems and ecology

NASA Astrophysics Data System (ADS)

Dhamala, Mukeshwar; Lai, Ying-Cheng

1999-02-01

Transient chaos is a common phenomenon in nonlinear dynamics of many physical, biological, and engineering systems. In applications it is often desirable to maintain sustained chaos even in parameter regimes of transient chaos. We address how to sustain transient chaos in deterministic flows. We utilize a simple and practical method, based on extracting the fundamental dynamics from time series, to maintain chaos. The method can result in control of trajectories from almost all initial conditions in the original basin of the chaotic attractor from which transient chaos is created. We apply our method to three problems: (1) voltage collapse in electrical power systems, (2) species preservation in ecology, and (3) elimination of undesirable bursting behavior in a chemical reaction system.

Robust Power Management Control for Stand-Alone Hybrid Power Generation System

NASA Astrophysics Data System (ADS)

Kamal, Elkhatib; Adouane, Lounis; Aitouche, Abdel; Mohammed, Walaa

2017-01-01

This paper presents a new robust fuzzy control of energy management strategy for the stand-alone hybrid power systems. It consists of two levels named centralized fuzzy supervisory control which generates the power references for each decentralized robust fuzzy control. Hybrid power systems comprises: a photovoltaic panel and wind turbine as renewable sources, a micro turbine generator and a battery storage system. The proposed control strategy is able to satisfy the load requirements based on a fuzzy supervisor controller and manage power flows between the different energy sources and the storage unit by respecting the state of charge and the variation of wind speed and irradiance. Centralized controller is designed based on If-Then fuzzy rules to manage and optimize the hybrid power system production by generating the reference power for photovoltaic panel and wind turbine. Decentralized controller is based on the Takagi-Sugeno fuzzy model and permits us to stabilize each photovoltaic panel and wind turbine in presence of disturbances and parametric uncertainties and to optimize the tracking reference which is given by the centralized controller level. The sufficient conditions stability are formulated in the format of linear matrix inequalities using the Lyapunov stability theory. The effectiveness of the proposed Strategy is finally demonstrated through a SAHPS (stand-alone hybrid power systems) to illustrate the effectiveness of the overall proposed method.

Solid polymer electrolyte water electrolysis preprototype subsystem. [oxygen production for life support systems on space stations

NASA Technical Reports Server (NTRS)

1979-01-01

Hardware and controls developed for an electrolysis demonstration unit for use with the life sciences payload program and in NASA's regenerative life support evaluation program are described. Components discussed include: the electrolysis module; power conditioner; phase separator-pump and hydrogen differential regulator; pressure regulation of O2, He, and N2; air-cooled heat exchanger; water accumulator; fluid flow sight gage assembly; catalytic O2/H2 sensor; gas flow sensors; low voltage power supply; 100 Amp DC contactor assembly; and the water purifier design.

Enhanced power quality based single phase photovoltaic distributed generation system

NASA Astrophysics Data System (ADS)

Panda, Aurobinda; Pathak, M. K.; Srivastava, S. P.

2016-08-01

This article presents a novel control strategy for a 1-ϕ 2-level grid-tie photovoltaic (PV) inverter to enhance the power quality (PQ) of a PV distributed generation (PVDG) system. The objective is to obtain the maximum benefits from the grid-tie PV inverter by introducing current harmonics as well as reactive power compensation schemes in its control strategy, thereby controlling the PV inverter to achieve multiple functions in the PVDG system such as: (1) active power flow control between the PV inverter and the grid, (2) reactive power compensation, and (3) grid current harmonics compensation. A PQ enhancement controller (PQEC) has been designed to achieve the aforementioned objectives. The issue of underutilisation of the PV inverter in nighttime has also been addressed in this article and for the optimal use of the system; the PV inverter is used as a shunt active power filter in nighttime. A prototype model of the proposed system is developed in the laboratory, to validate the effectiveness of the control scheme, and is tested with the help of the dSPACE DS1104 platform.

Core Dynamics Analysis for Reactivity Insertion and Loss of Coolant Flow Tests Using the High Temperature Engineering Test Reactor

NASA Astrophysics Data System (ADS)

Takamatsu, Kuniyoshi; Nakagawa, Shigeaki; Takeda, Tetsuaki

Safety demonstration tests using the High Temperature Engineering Test Reactor (HTTR) are in progress to verify its inherent safety features and improve the safety technology and design methodology for High-temperature Gas-cooled Reactors (HTGRs). The reactivity insertion test is one of the safety demonstration tests for the HTTR. This test simulates the rapid increase in the reactor power by withdrawing the control rod without operating the reactor power control system. In addition, the loss of coolant flow tests has been conducted to simulate the rapid decrease in the reactor power by tripping one, two or all out of three gas circulators. The experimental results have revealed the inherent safety features of HTGRs, such as the negative reactivity feedback effect. The numerical analysis code, which was named-ACCORD-, was developed to analyze the reactor dynamics including the flow behavior in the HTTR core. We have modified this code to use a model with four parallel channels and twenty temperature coefficients. Furthermore, we added another analytical model of the core for calculating the heat conduction between the fuel channels and the core in the case of the loss of coolant flow tests. This paper describes the validation results for the newly developed code using the experimental results. Moreover, the effect of the model is formulated quantitatively with our proposed equation. Finally, the pre-analytical result of the loss of coolant flow test by tripping all gas circulators is also discussed.

Temperature control system for a J-module heat exchanger

DOEpatents

Basdekas, Demetrios L.; Macrae, George; Walsh, Joseph M.

1978-01-01

The level of primary fluid is controlled to change the effective heat transfer area of a heat exchanger utilized in a liquid metal nuclear power plant to eliminate the need for liquid metal control valves to regulate the flow of primary fluid and the temperature of the effluent secondary fluid.

An Operational Short-Term Forecasting System for Regional Hydropower Management

NASA Astrophysics Data System (ADS)

Gronewold, A.; Labuhn, K. A.; Calappi, T. J.; MacNeil, A.

2017-12-01

The Niagara River is the natural outlet of Lake Erie and drains four of the five Great lakes. The river is used to move commerce and is home to both sport fishing and tourism industries. It also provides nearly 5 million kilowatts of hydropower for approximately 3.9 million homes. Due to a complex international treaty and the necessity of balancing water needs for an extensive tourism industry, the power entities operating on the river require detailed and accurate short-term river flow forecasts to maximize power output. A new forecast system is being evaluated that takes advantage of several previously independent components including the NOAA Lake Erie operational Forecast System (LEOFS), a previously developed HEC-RAS model, input from the New York Power Authority(NYPA) and Ontario Power Generation (OPG) and lateral flow forecasts for some of the tributaries provided by the NOAA Northeast River Forecast Center (NERFC). The Corps of Engineers updated the HEC-RAS model of the upper Niagara River to use the output forcing from LEOFS and a planned Grass Island Pool elevation provided by the power entities. The entire system has been integrated at the NERFC; it will be run multiple times per day with results provided to the Niagara River Control Center operators. The new model helps improve discharge forecasts by better accounting for dynamic conditions on Lake Erie. LEOFS captures seiche events on the lake that are often several meters of displacement from still water level. These seiche events translate into flow spikes that HEC-RAS routes downstream. Knowledge of the peak arrival time helps improve operational decisions at the Grass Island Pool. This poster will compare and contrast results from the existing operational flow forecast and the new integrated LEOFS/HEC-RAS forecast. This additional model will supply the Niagara River Control Center operators with multiple forecasts of flow to help improve forecasting under a wider variety of conditions.

Controls on summer low flow

NASA Astrophysics Data System (ADS)

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.

Temperature-gated thermal rectifier for active heat flow control.

PubMed

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 (<1%). To the best of our knowledge, this is the first demonstration of solid-state active-thermal devices with a large rectification in the 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.

Fluid Flow Characteristics and Porosity Behavior in Full Penetration Laser Welding of a Titanium Alloy

NASA Astrophysics Data System (ADS)

Chang, Baohua; Allen, Chris; Blackburn, Jon; Hilton, Paul; Du, Dong

2015-04-01

In this paper, a computational fluid mechanics model is developed for full penetration laser welding of titanium alloy Ti6Al4V. This has been used to analyze possible porosity formation mechanisms, based on predictions of keyhole behavior and fluid flow characteristics in the weld pool. Numerical results show that when laser welding 3 mm thickness titanium alloy sheets with given laser beam focusing optics, keyhole depth oscillates before a full penetration keyhole is formed, but thereafter keyhole collapses are not predicted numerically. For lower power, lower speed welding, the fluid flow behind the keyhole is turbulent and unstable, and vortices are formed. Molten metal is predicted to flow away from the center plane of the weld pool, and leave a gap or void within the weld pool behind the keyhole. For higher power, higher speed welding, fluid flow is less turbulent, and such vortices are not formed. Corresponding experimental results show that porosity was absent in the melt runs made at higher power and higher welding speed. In contrast, large pores were present in melt runs made at lower power and lower welding speed. Based on the combination of experimental results and numerical predictions, it is proposed that porosity formation when keyhole laser welding may result from turbulent fluid flow behind the keyhole, with the larger the value of associated Reynolds number, the higher the possibility of porosity formation. For such fluid flow controlled porosities, measures to decrease Reynolds number of the fluid flow close to the keyhole could prove effective in reducing or avoiding porosity.

Performance characteristics of plane-wall venturi-like reverse flow diverters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, G.V.; Counce, R.M.

1984-02-01

The results of an analytical and experimental study of plane-wall venturi-like reverse flow diverters (RFD) are presented. In general, the flow characteristics of the RFD are reasonably well predicted by the mathematical model of the RFD, although a divergence between theory and data is observed for the output characteristics in the reverse flow mode as the output impedance is reduced. Overall, the performance of these devices indicates their usefulness in fluid control and fluid power systems, such as displacement pumping systems.

Performance characteristics of plane-wall venturi-like reverse flow diverters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, G.V.; Counce, R.M.

1982-01-01

The results of an analytical and experimental study of plane-wall venturi-like reverse flow diverters (RFD) are presented. In general, the flow characteristics of the RFD are reasonably well predicted by the mathematical model of the RFD, although a divergence between theory and data is observed for the output characteristics in the reverse flow mode as the output impedance is reduced. Overall, the performance of these devices indicates their usefulness in fluid control and fluid power systems, such as displacement pumping systems.

Increasing power generation in horizontal axis wind turbines using optimized flow control

NASA Astrophysics Data System (ADS)

Cooney, John A., Jr.

In order to effectively realize future goals for wind energy, the efficiency of wind turbines must increase beyond existing technology. One direct method for achieving increased efficiency is by improving the individual power generation characteristics of horizontal axis wind turbines. The potential for additional improvement by traditional approaches is diminishing rapidly however. As a result, a research program was undertaken to assess the potential of using distributed flow control to increase power generation. The overall objective was the development of validated aerodynamic simulations and flow control approaches to improve wind turbine power generation characteristics. BEM analysis was conducted for a general set of wind turbine models encompassing last, current, and next generation designs. This analysis indicated that rotor lift control applied in Region II of the turbine power curve would produce a notable increase in annual power generated. This was achieved by optimizing induction factors along the rotor blade for maximum power generation. In order to demonstrate this approach and other advanced concepts, the University of Notre Dame established the Laboratory for Enhanced Wind Energy Design (eWiND). This initiative includes a fully instrumented meteorological tower and two pitch-controlled wind turbines. The wind turbines are representative in their design and operation to larger multi-megawatt turbines, but of a scale that allows rotors to be easily instrumented and replaced to explore new design concepts. Baseline data detailing typical site conditions and turbine operation is presented. To realize optimized performance, lift control systems were designed and evaluated in CFD simulations coupled with shape optimization tools. These were integrated into a systematic design methodology involving BEM simulations, CFD simulations and shape optimization, and selected experimental validation. To refine and illustrate the proposed design methodology, a complete design cycle was performed for the turbine model incorporated in the wind energy lab. Enhanced power generation was obtained through passive trailing edge shaping aimed at reaching lift and lift-to-drag goals predicted to optimize performance. These targets were determined by BEM analysis to improve power generation characteristics and annual energy production (AEP) for the wind turbine. A preliminary design was validated in wind tunnel experiments on a 2D rotor section in preparation for testing in the full atmospheric environment of the eWiND Laboratory. These tests were performed for the full-scale geometry and atmospheric conditions. Upon making additional improvements to the shape optimization tools, a series of trailing edge additions were designed to optimize power generation. The trailing edge additions were predicted to increase the AEP by up to 4.2% at the White Field site. The pieces were rapid-prototyped and installed on the wind turbine in March, 2014. Field tests are ongoing.

ELECTRICAL PROTECTIVE DEVICE

DOEpatents

Baker, W.R.

1958-05-01

A protective system for high-energy resonant cavities is described. It is particularly directed to the discharging of resonant cavities for preventing energy back flow through associated equipment as a result of faults. The invention in general provides means defining a spark gap communicating with the interior of a cavity or waveguide adapted for high-power energization or an evacuated chamber containing an electrode having a large power differential from the wall or other electrode. A control or trigger circuit is connected between a power supply energizing the cavity and the spark gap whereby reverse current flow in the power supply circuit instantaneously triggers the spark gap to initiate discharge within the cavity, whereupon cavity energy discharges across the gap, or with an electrode present the electrode discharges to one of the spark gap elements.

Formation of visual memories controlled by gamma power phase-locked to alpha oscillations.

PubMed

Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jiang, Haiteng; Gross, Joachim; Jensen, Ole

2016-06-16

Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity.

Formation of visual memories controlled by gamma power phase-locked to alpha oscillations

PubMed Central

Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jiang, Haiteng; Gross, Joachim; Jensen, Ole

2016-01-01

Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity. PMID:27306959

Formation of visual memories controlled by gamma power phase-locked to alpha oscillations

NASA Astrophysics Data System (ADS)

Park, Hyojin; Lee, Dong Soo; Kang, Eunjoo; Kang, Hyejin; Hahm, Jarang; Kim, June Sic; Chung, Chun Kee; Jiang, Haiteng; Gross, Joachim; Jensen, Ole

2016-06-01

Neuronal oscillations provide a window for understanding the brain dynamics that organize the flow of information from sensory to memory areas. While it has been suggested that gamma power reflects feedforward processing and alpha oscillations feedback control, it remains unknown how these oscillations dynamically interact. Magnetoencephalography (MEG) data was acquired from healthy subjects who were cued to either remember or not remember presented pictures. Our analysis revealed that in anticipation of a picture to be remembered, alpha power decreased while the cross-frequency coupling between gamma power and alpha phase increased. A measure of directionality between alpha phase and gamma power predicted individual ability to encode memory: stronger control of alpha phase over gamma power was associated with better memory. These findings demonstrate that encoding of visual information is reflected by a state determined by the interaction between alpha and gamma activity.

A decision tree-based on-line preventive control strategy for power system transient instability prevention

NASA Astrophysics Data System (ADS)

Xu, Yan; Dong, Zhao Yang; Zhang, Rui; Wong, Kit Po

2014-02-01

Maintaining transient stability is a basic requirement for secure power system operations. Preventive control deals with modifying the system operating point to withstand probable contingencies. In this article, a decision tree (DT)-based on-line preventive control strategy is proposed for transient instability prevention of power systems. Given a stability database, a distance-based feature estimation algorithm is first applied to identify the critical generators, which are then used as features to develop a DT. By interpreting the splitting rules of DT, preventive control is realised by formulating the rules in a standard optimal power flow model and solving it. The proposed method is transparent in control mechanism, on-line computation compatible and convenient to deal with multi-contingency. The effectiveness and efficiency of the method has been verified on New England 10-machine 39-bus test system.

Nano-composite insert in 1D waveguides for control of elastic power flow

NASA Astrophysics Data System (ADS)

Vignesh, P. S.; Mitra, Mira; Gopalakrishnan, S.

2007-01-01

In this paper, carbon nanotube embedded polymer composite/nano-composites are used to regulate power flow from its source to other parts of the structure. This is done by inserting nano-composite strips in the waveguides which are modelled here as isotropic Euler-Bernoulli beams with axial, transverse and rotational degrees of freedom. The power flow is due to wave propagation resulting from a high frequency broadband impulse load. The underlying concept is that the high stiffness of the insert reduces the wave transmission between different parts of the structures. The simulations are done using a wavelet based spectral finite element (WSFE) technique which is specially tailored for such high frequency wave propagation analysis. Numerical experiments are performed to illustrate the use of inserts in maintaining the power flow in a certain region of the structure below a given threshold value which may be specified depending on various applications. The effects of parameters such as the volume fraction of carbon nanotube (CNT) in the polymer, and the length and position of the inserts are also studied. These studies help in defining the optimal volume fraction of CNT and length of the insert for a specified structural configuration.

Direct power production from a water salinity difference in a membrane-modified supercapacitor flow cell.

PubMed

Sales, B B; Saakes, M; Post, J W; Buisman, C J N; Biesheuvel, P M; Hamelers, H V M

2010-07-15

The entropy increase of mixing two solutions of different salt concentrations can be harnessed to generate electrical energy. Worldwide, the potential of this resource, the controlled mixing of river and seawater, is enormous, but existing conversion technologies are still complex and expensive. Here we present a small-scale device that directly generates electrical power from the sequential flow of fresh and saline water, without the need for auxiliary processes or converters. The device consists of a sandwich of porous "supercapacitor" electrodes, ion-exchange membranes, and a spacer and can be further miniaturized or scaled-out. Our results demonstrate that alternating the flow of saline and fresh water through a capacitive cell allows direct autogeneration of voltage and current and consequently leads to power generation. Theoretical calculations aid in providing directions for further optimization of the properties of membranes and electrodes.

Chance-Constrained AC Optimal Power Flow for Distribution Systems With Renewables

DOE Office of Scientific and Technical Information (OSTI.GOV)

DallAnese, Emiliano; Baker, Kyri; Summers, Tyler

This paper focuses on distribution systems featuring renewable energy sources (RESs) and energy storage systems, and presents an AC optimal power flow (OPF) approach to optimize system-level performance objectives while coping with uncertainty in both RES generation and loads. The proposed method hinges on a chance-constrained AC OPF formulation where probabilistic constraints are utilized to enforce voltage regulation with prescribed probability. A computationally more affordable convex reformulation is developed by resorting to suitable linear approximations of the AC power-flow equations as well as convex approximations of the chance constraints. The approximate chance constraints provide conservative bounds that hold for arbitrarymore » distributions of the forecasting errors. An adaptive strategy is then obtained by embedding the proposed AC OPF task into a model predictive control framework. Finally, a distributed solver is developed to strategically distribute the solution of the optimization problems across utility and customers.« less

Assessing China’s Soft Power in Asia: Implications for U.S. Strategy

DTIC Science & Technology

2012-04-01

especially as it might be thought of as an instrument of policy.”19 Gray‟s critiques deride the strategic usefulness of soft 8 power based on the length...soft power flows from hard power, but not the reverse. Gray critiques soft power as if it is mutually exclusive of hard power; that is, if you use ...and film …the freedom is not there. (The Chinese government) really tries to control and manage it, and there is self- censorship as well. That is

Neuro-Fuzzy Computational Technique to Control Load Frequency in Hydro-Thermal Interconnected Power System

NASA Astrophysics Data System (ADS)

Prakash, S.; Sinha, S. K.

2015-09-01

In this research work, two areas hydro-thermal power system connected through tie-lines is considered. The perturbation of frequencies at the areas and resulting tie line power flows arise due to unpredictable load variations that cause mismatch between the generated and demanded powers. Due to rising and falling power demand, the real and reactive power balance is harmed; hence frequency and voltage get deviated from nominal value. This necessitates designing of an accurate and fast controller to maintain the system parameters at nominal value. The main purpose of system generation control is to balance the system generation against the load and losses so that the desired frequency and power interchange between neighboring systems are maintained. The intelligent controllers like fuzzy logic, artificial neural network (ANN) and hybrid fuzzy neural network approaches are used for automatic generation control for the two area interconnected power systems. Area 1 consists of thermal reheat power plant whereas area 2 consists of hydro power plant with electric governor. Performance evaluation is carried out by using intelligent (ANFIS, ANN and fuzzy) control and conventional PI and PID control approaches. To enhance the performance of controller sliding surface i.e. variable structure control is included. The model of interconnected power system has been developed with all five types of said controllers and simulated using MATLAB/SIMULINK package. The performance of the intelligent controllers has been compared with the conventional PI and PID controllers for the interconnected power system. A comparison of ANFIS, ANN, Fuzzy and PI, PID based approaches shows the superiority of proposed ANFIS over ANN, fuzzy and PI, PID. Thus the hybrid fuzzy neural network controller has better dynamic response i.e., quick in operation, reduced error magnitude and minimized frequency transients.

Geomorphic versus land use controls on suspended sediment rating curves

NASA Astrophysics Data System (ADS)

Belmont, P.; Vaughan, A. A.; Fisher, A. C. N.

2017-12-01

The relation between river discharge (Q) and suspended sediment (SS) concentration reflects the degree to which sediment sources are accessed or depleted across the range of flow conditions. Increased availability of high resolution topography and land use data greatly enhance our ability to evaluate linkages between characteristics of these sediment rating curves (SRCs) and the geomorphic features that influence them. We evaluated Q-SS relations at 45 gages throughout Minnesota, USA representing a wide variety of landscape settings in terms of topography, land use, and geologic history. We characterized the SRCs according to the overall shape, steepness (exponent), vertical offset (coefficient) and SS concentration under low flow (90% exceedance) conditions. Rivers exhibited three distinct SRC shapes, simple power functions, threshold power functions and peaked power functions. We used random forest models to analyze relations between SRC parameters and attributes of the watershed as well as the near-channel environment. The model correctly classified 78% of SRC shapes and explained 60% of variance in the SRC exponent, 43% of the SRC coefficient for rising limb samples, and 45% of variance under low flow conditions. Notably, the random forest models predict that near-channel morphology predominately controls both the shape and steepness of the sediment rating curves. Land use predominately controls the vertical offset (coefficient) and SS concentration under low flow conditions. These findings suggest that land use and watershed restoration practices may have little capacity to alter the shape and steepness of these curves as these characteristics may be dictated by the geologic and geomorphic setting. Rather, human influences in the watershed may exhibit the greatest influence on suspended sediment concentrations at moderate to low flows. Criteria to evaluate improvements in water quality as a result of changes in land management might be most meaningful if they target these moderate to low flow conditions.

Development of the Optimum Operation Scheduling Model of Domestic Electric Appliances for the Supply-Demand Adjustment in a Power System

NASA Astrophysics Data System (ADS)

Ikegami, Takashi; Iwafune, Yumiko; Ogimoto, Kazuhiko

The high penetration of variable renewable generation such as Photovoltaic (PV) systems will cause the issue of supply-demand imbalance in a whole power system. The activation of the residential power usage, storage and generation by sophisticated scheduling and control using the Home Energy Management System (HEMS) will be needed to balance power supply and demand in the near future. In order to evaluate the applicability of the HEMS as a distributed controller for local and system-wide supply-demand balances, we developed an optimum operation scheduling model of domestic electric appliances using the mixed integer linear programming. Applying this model to several houses with dynamic electricity prices reflecting the power balance of the total power system, it was found that the adequate changes in electricity prices bring about the shift of residential power usages to control the amount of the reverse power flow due to excess PV generation.

Performance evaluation of the Russian SPT-100 thruster at NASA LeRC

NASA Technical Reports Server (NTRS)

Sankovic, John M.; Hamley, John A.; Haag, Thomas W.

1994-01-01

Performance measurements of a Russian flight-model SPT-100 thruster were obtained as part of a comprehensive program to evaluate engineering issues pertinent to integration with Western spacecraft. Power processing was provided by a US Government developed laboratory power conditioner. When received the thruster had been subjected to only a few hours of acceptance testing by the manufacturer. Accumulated operating time during this study totalled 148 h and included operation of both cathodes. Cathode flow fraction was controlled both manually and using the flow splitter contained within the supplied xenon flow controller. Data were obtained at current levels ranging from 3 A to 5 A and thruster voltages ranging from 200 V to 300 V. Testing centered on the design power of 1.35 kW with a discharge current of 4.5 A. The effects of facility pressure on thruster operation were examined by varying the pressure via injection of xenon into the vacuum chamber. The facility pressure had a significant effect on thruster performance and stability at the conditions tested. Periods of current instabilities were noted throughout the testing period and became more frequent as testing progressed. Performance during periods of stability agreed with previous data obtained in Russian laboratories.

Guide to Flow Measurement for Electric Propulsion Systems

NASA Technical Reports Server (NTRS)

Frieman, Jason D.; Walker, Mitchell L. R.; Snyder, Steve

2013-01-01

In electric propulsion (EP) systems, accurate measurement of the propellant mass flow rate of gas or liquid to the thruster and external cathode is a key input in the calculation of thruster efficiency and specific impulse. Although such measurements are often achieved with commercial mass flow controllers and meters integrated into propellant feed systems, the variability in potential propellant options and flow requirements amongst the spectrum of EP power regimes and devices complicates meter selection, integration, and operation. At the direction of the Committee on Standards for Electric Propulsion Testing, a guide was jointly developed by members of the electric propulsion community to establish a unified document that contains the working principles, methods of implementation and analysis, and calibration techniques and recommendations on the use of mass flow meters in laboratory and spacecraft electric propulsion systems. The guide is applicable to EP devices of all types and power levels ranging from microthrusters to high-power ion engines and Hall effect thrusters. The establishment of a community standard on mass flow metering will help ensure the selection of the proper meter for each application. It will also improve the quality of system performance estimates by providing comprehensive information on the physical phenomena and systematic errors that must be accounted for during the analysis of flow measurement data. This paper will outline the standard methods and recommended practices described in the guide titled "Flow Measurement for Electric Propulsion Systems."

Subsonic flight test evaluation of a performance seeking control algorithm on an F-15 airplane

NASA Technical Reports Server (NTRS)

Gilyard, Glenn B.; Orme, John S.

1992-01-01

The subsonic flight test evaluation phase of the NASA F-15 (powered by F 100 engines) performance seeking control program was completed for single-engine operation at part- and military-power settings. The subsonic performance seeking control algorithm optimizes the quasi-steady-state performance of the propulsion system for three modes of operation. The minimum fuel flow mode minimizes fuel consumption. The minimum thrust mode maximizes thrust at military power. Decreases in thrust-specific fuel consumption of 1 to 2 percent were measured in the minimum fuel flow mode; these fuel savings are significant, especially for supersonic cruise aircraft. Decreases of up to approximately 100 degree R in fan turbine inlet temperature were measured in the minimum temperature mode. Temperature reductions of this magnitude would more than double turbine life if inlet temperature was the only life factor. Measured thrust increases of up to approximately 15 percent in the maximum thrust mode cause substantial increases in aircraft acceleration. The system dynamics of the closed-loop algorithm operation were good. The subsonic flight phase has validated the performance seeking control technology, which can significantly benefit the next generation of fighter and transport aircraft.

Operating characteristics of 120-millimeter-bore ball bearings at 3 million DN

NASA Technical Reports Server (NTRS)

Zaretsky, E. V.; Bamberger, E. N.; Signer, H.

1974-01-01

A parametric study was performed with split inner-race 120-mm-bore angular-contact ball bearings at a speed of 25,000 rpm (3 million DN) at initial contact angles of 20 deg and 24 deg. Provisions were made for outer- and inner-race cooling and for injection of lubricant into the bearing through a number of radial holes in the split inner-race of the bearing. Oil flow and coolant rate to the bearing was controlled and varied for a total up to approximately 3.2 gal/min. Bearing temperature was found to decrease as the total lubricant flow to the bearing increased. However, at intermediate flow rates temperature began to increase with increasing flow. Power consumption increased with increasing flow rate. Bearing operating temperature, differences in temperatures between the inner and outer races, and bearing power consumption can be tuned to any desirable operating requirement. Cage speed increased by not more than 2 percent with increasing oil flow to the inner race.

Dense Array Optimization of Cross-Flow Turbines

NASA Astrophysics Data System (ADS)

Scherl, Isabel; Strom, Benjamin; Brunton, Steven; Polagye, Brian

2017-11-01

Cross-flow turbines, where the axis of rotation is perpendicular to the freestream flow, can be used to convert the kinetic energy in wind or water currents to electrical power. By taking advantage of mean and time-resolved wake structures, the optimal density of an array of cross-flow turbines has the potential for higher power output per unit area of land or sea-floor than an equivalent array of axial-flow turbines. In addition, dense arrays in tidal or river channels may be able to further elevate efficiency by exploiting flow confinement and surface proximity. In this work, a two-turbine array is optimized experimentally in a recirculating water channel. The spacing between turbines, as well as individual and coordinated turbine control strategies are optimized. Array efficiency is found to exceed the maximum efficiency for a sparse array (i.e., no interaction between turbines) for stream-wise rotor spacing of less than two diameters. Results are discussed in the context of wake measurements made behind a single rotor.

Modelling and optimization of transient processes in line focusing power plants with single-phase heat transfer medium

NASA Astrophysics Data System (ADS)

Noureldin, K.; González-Escalada, L. M.; Hirsch, T.; Nouri, B.; Pitz-Paal, R.

2016-05-01

A large number of commercial and research line focusing solar power plants are in operation and under development. Such plants include parabolic trough collectors (PTC) or linear Fresnel using thermal oil or molten salt as the heat transfer medium (HTM). However, the continuously varying and dynamic solar condition represent a big challenge for the plant control in order to optimize its power production and to keep the operation safe. A better understanding of the behaviour of such power plants under transient conditions will help reduce defocusing instances, improve field control, and hence, increase the energy yield and confidence in this new technology. Computational methods are very powerful and cost-effective tools to gain such understanding. However, most simulation models described in literature assume equal mass flow distributions among the parallel loops in the field or totally decouple the flow and thermal conditions. In this paper, a new numerical model to simulate a whole solar field with single-phase HTM is described. The proposed model consists of a hydraulic part and a thermal part that are coupled to account for the effect of the thermal condition of the field on the flow distribution among the parallel loops. The model is specifically designed for large line-focusing solar fields offering a high degree of flexibility in terms of layout, condition of the mirrors, and spatially resolved DNI data. Moreover, the model results have been compared to other simulation tools, as well as experimental and plant data, and the results show very good agreement. The model can provide more precise data to the control algorithms to improve the plant control. In addition, short-term and accurate spatially discretized DNI forecasts can be used as input to predict the field behaviour in-advance. In this paper, the hydraulic and thermal parts, as well as the coupling procedure, are described and some validation results and results of simulating an example field are shown.

Flow separation on wind turbines blades

NASA Astrophysics Data System (ADS)

Corten, G. P.

2001-01-01

In the year 2000, 15GW of wind power was installed throughout the world, producing 100PJ of energy annually. This contributes to the total electricity demand by only 0.2%. Both the installed power and the generated energy are increasing by 30% per year world-wide. If the airflow over wind turbine blades could be controlled fully, the generation efficiency and thus the energy production would increase by 9%. Power Control To avoid damage to wind turbines, they are cut out above 10 Beaufort (25 m/s) on the wind speed scale. A turbine could be designed in such a way that it converts as much power as possible in all wind speeds, but then it would have to be to heavy. The high costs of such a design would not be compensated by the extra production in high winds, since such winds are rare. Therefore turbines usually reach maximum power at a much lower wind speed: the rated wind speed, which occurs at about 6 Beaufort (12.5 m/s). Above this rated speed, the power intake is kept constant by a control mechanism. Two different mechanisms are commonly used. Active pitch control, where the blades pitch to vane if the turbine maximum is exceeded or, passive stall control, where the power control is an implicit property of the rotor. Stall Control The flow over airfoils is called "attached" when it flows over the surface from the leading edge to the trailing edge. However, when the angle of attack of the flow exceeds a certain critical angle, the flow does not reach the trailing edge, but leaves the surface at the separation line. Beyond this line the flow direction is reversed, i.e. it flows from the trailing edge backward to the separation line. A blade section extracts much less energy from the flow when it separates. This property is used for stall control. Stall controlled rotors always operate at a constant rotation speed. The angle of attack of the flow incident to the blades is determined by the blade speed and the wind speed. Since the latter is variable, it determines the angle of attack. The art of designing stall rotors is to make the separated area on the blades extend in such a way, that the extracted power remains precisely constant, independent of the wind speed, while the power in the wind at cut-out exceeds the maximum power of the turbine by a factor of 8. Since the stall behaviour is influenced by many parameters, this demand cannot be easily met. However, if it can be met, the advantage of stall control is its passive operation, which is reliable and cheap. Problem Definition In practical application, stall control is not very accurate and many stall-controlled turbines do not meet their specifications. Deviations of the design-power in the order of tens of percent are regular. In the nineties, the aerodynamic research on these deviations focussed on: profile aerodynamics, computational fluid dynamics, rotational effects on separation and pressure measurements on test turbines. However, this did not adequately solve the actual problems with stall turbines. In this thesis, we therefore formulated the following as the essential question: "Does the separated blade area really extend with the wind speed, as we predict?" To find the answer a measurement technique was required, which 1) was applicable on large commercial wind turbines, 2) could follow the dynamic changes of the stall pattern, 3) was not influenced by the centrifugal force and 4) did not disturb the flow. Such a technique was not available, therefore we decided to develop it. Stall Flag Method For this method, a few hundred indicators are fixed to the rotor blades in a special pattern. These indicators, called "stall flags" are patented by the Netherlands Energy Research Foundation (ECN). They have a retro-reflective area which, depending on the flow direction, is or is not covered. A powerful light source in the field up to 500m behind the turbine illuminates the swept rotor area. The uncovered reflectors reflect the light to the source, where a digital video camera records the dynamic stall patterns. The images are analysed by image processing software that we developed. The program extracts the stall pattern, the blade azimuth angles and the rotor speed from the stall flags. It also measures the yaw error and the wind speed from the optical signals of other sensors, which are recorded simultaneously. We subsequently characterise the statistical stall behaviour from the sequences of thousands of analysed images. For example, the delay in the stall angle by vortex generators can be measured within 1° of accuracy from the stall flag signals. Properties of the Stall Flag The new indicators are compared to the classic tufts. Stall flags are pressure driven while tufts are driven by frictional drag, which means that they have more drag. The self-excited motion of tufts, due to the Kelvin-Helmholtz instability, complicates the interpretation and gives more drag. We designed stall flags in such a way that this instability is avoided. An experiment with a 65cm diameter propeller confirms the independence of stall flags from the centrifugal force and that stall flags respond quickly to changes in the flow. We developed an optical model of the method to find an optimum set-up. With the present system, we can take measurements on turbines of all actual diameters. The stall flag responds to separated flow with an optical signal. The contrast of this signal exceeds that of tuft-signals by a factor of at least 1000. To detect the stall flag signal we need a factor of 25 fewer pixels of the CCD chip than is necessary for tufts. Stall flags applied on fast moving objects may show light tracks due to motion blur, which in fact yields even more information. In the case of tuft visualisations, even a slight motion blur is fatal. Principal Results In dealing with the fundamental theory of wind turbines, we found a new aspect of the conversion efficiency of a wind turbine, which also concerns the stall behaviour. Another new aspect concerns the effects of rotation on stall. By using the stall flag method, we were able to clear up two practical problems that seriously threatened the performance of stall turbines. These topics will be described briefly. 1. Inherent Heat Generation The classic result for an actuator disk representing a wind turbine is that the power extracted equals the kinetic power transferred. This is a consequence of disregarding the flow around the disk. When this flow is included, we need to introduce a heat generation term in the energy balance. This has the practical consequence that an actuator disk at the Lanchester-Betz limit transfers 50% more kinetic energy than it extracts. This surplus is dissipated in heat. Using this new argument, together with a classic argument on induction, we see no reason to introduce the concept of edge-forces on the tips of the rotor blades (Van Kuik, 1991). We rather recommend following the ideas of Lanchester (1915) on the edge of the actuator disk and on the wind speed at the disc. We analyse the concept induction, and show that correcting for the aspect ratio, for induced drag and application of Blade Element Momentum Theory all have the same significance for a wind turbine. Such corrections are sometimes made twice (Viterna & Corrigan, 1981). 2. Rotational Effects on Flow Separation In designing wind turbine rotors, one uses the aerodynamic characteristics measured in the wind tunnel on fixed aerodynamic profiles. These characteristics are corrected for the effects of rotation and subsequently used for wind turbine rotors. Such a correction was developed by Snel (1990-1999). This correction is based on boundary layer theory, the validity of which we question in regard to separated flow. We estimated the effects of rotation on flow separation by arguing that the separation layer is thick so the velocity gradients are small and viscosity can be neglected. We add the argument that the chord-wise speed and its derivative normal to the wall is zero at the separation line, which causes the terms with the chord-wise speed or accelerations to disappear. The conclusion is that the chord-wise pressure gradient balances the Coriolis force. By doing so we obtain a simple set of equations that can be solved analytically. Subsequently, our model predicts that the convective term with the radial velocity (vrvr/r) is dominant in the equation for the r-direction, precisely the term that was neglected in Snel's analysis. 3. Multiple Power Levels Several large commercial wind turbines demonstrate drops in maximum power levels up to 45%, under apparently equal conditions. Earlier studies attempting to explain this effect by technical malfunctioning, aerodynamic instabilities and blade contamination effects estimated with computational fluid dynamics, have not yet yielded a plausible result. We formulated many hypotheses, three of which were useful. By taking stall flag measurements and making two other crucial experiments, we could confirm one of those three hypotheses: the insect hypothesis. Insects only fly in low wind, impacting upon the blades at specific locations. In these conditions, the insectual remains are located at positions where roughness has little influence on the profile performance, so that the power is not affected. In high winds however, the flow around the blades has changed. As a result, the positions at which the insects have impacted at low winds are very sensitive to contamination. So the contamination level changes at low wind when insects fly and this level determines the power in high winds when insects do not fly. As a consequence we get discrete power levels in high winds. The other two hypotheses, which did not cause the multiple power levels for the case we studied, gave rise to two new insights. First, we expect the power to depend on the wind direction at sites where the shape of the terrain concentrates the wind. In this case the power level of all turbine types, including pitch regulated ones, will be affected. Second, we infer heuristically that the stalled area on wind turbine blades will adapt continuously to wind variations. Therefore, the occurrence of strong bi-stable stall-hysteresis, which most blade sections demonstrate in the wind tunnel, is lost. This has been confirmed by taking special stall flag measurements. 4. Deviation of Specifications The maximum power of stall controlled wind turbines often shows large systematic deviations from the design. We took stall flag measurements on a rotor, the maximum power of which was 30% too high, so that the turbine had to be cut out far below the designed cut-out wind speed. We immediately observed the blade areas with deviating stall behaviour. Some areas that should have stalled did not and caused the excessive power. We adapted those areas by shifting the vortex generators. In this way we obtained a power curve that met the design much more closely and we realised a production increase of 8%.

Heat And Mass Transfer Analysis of a Film Evaporative MEMS Tunable Array

NASA Astrophysics Data System (ADS)

O'Neill, William J.

This thesis details the heat and mass transfer analysis of a MEMs microthruster designed to provide propulsive, attitude control and thermal control capabilities to a cubesat. This thruster is designed to function by retaining water as a propellant and applying resistive heating in order to increase the temperature of the liquid-vapor interface to either increase evaporation or induce boiling to regulate mass flow. The resulting vapor is then expanded out of a diverging nozzle to produce thrust. Because of the low operating pressure and small length scale of this thruster, unique forms of mass transfer analysis such as non-continuum gas flow were modeled using the Direct Simulation Monte Carlo method. Continuum fluid/thermal simulations using COMSOL Multiphysics have been applied to model heat and mass transfer in the solid and liquid portions of the thruster. The two methods were coupled through variables at the liquid-vapor interface and solved iteratively by the bisection method. The simulations presented in this thesis confirm the thermal valving concept. It is shown that when power is applied to the thruster there is a nearly linear increase in mass flow and thrust. Thus, mass flow can be regulated by regulating the applied power. This concept can also be used as a thermal control device for spacecraft.

Hold-up power supply for flash memory

NASA Technical Reports Server (NTRS)

Ott, William E. (Inventor)

2004-01-01

A hold-up power supply for flash memory systems is provided. The hold-up power supply provides the flash memory with the power needed to temporarily operate when a power loss exists. This allows the flash memory system to complete any erasures and writes, and thus allows it to shut down gracefully. The hold-up power supply detects when a power loss on a power supply bus is occurring and supplies the power needed for the flash memory system to temporally operate. The hold-up power supply stores power in at least one capacitor. During normal operation, power from a high voltage supply bus is used to charge the storage capacitors. When a power supply loss is detected, the power supply bus is disconnected from the flash memory system. A hold-up controller controls the power flow from the storage capacitors to the flash memory system. The hold-up controller uses feedback to assure that the proper voltage is provided from the storage capacitors to the flash memory system. This power supplied by the storage capacitors allows the flash memory system to complete any erasures and writes, and thus allows the flash memory system to shut down gracefully.

Influence of TCSC Devices on Congestion Management in a Deregulated Power System Using Evolutionary Programming Technique

NASA Astrophysics Data System (ADS)

Ananthichristy, A., Dr.; Elanthirayan, R.; Brindha, R., Dr.; Siddhiq, M. S.; Venkatesh, N.; Harshit, M. V.; Nikhilreddy, M.

2018-04-01

Congestion management is one of the technical challenges in power system deregulation. In deregulated electricity market it may always not be possible to dispatch all of the contracted power transactions due to congestion of the transmission corridors. Transmission congestion occurs when there is insufficient transmission capacity to simultaneously accommodate all constraints for transmission of a line. Flexible Alternative Current Transmission System (FACTS) devices can be an alternative to reduce the flows in the heavily loaded lines, resulting in an increased loadability, low system loss, improved stability of the network, reduced cost of production and fulfilled contractual requirement by controlling the power flow in the network. A method to determine the optimal location of FACTS has been suggested based on reduction of total system VAR power losses. The simulation was done on IEEE 14 bus system and results were obtained.

Glow Discharge Plasma Demonstrated for Separation Control in the Low-Pressure Turbine

NASA Technical Reports Server (NTRS)

Ashpis, David e.; Hultgren, Lennart S.

2004-01-01

Flow separation in the low-pressure turbine (LPT) is a major barrier that limits further improvements of aerodynamic designs of turbine airfoils. The separation is responsible for performance degradation, and it prevents the design of highly loaded airfoils. The separation can be delayed, reduced, or eliminated completely if flow control techniques are used. Successful flow control technology will enable breakthrough improvements in gas turbine performance and design. The focus of this research project was the development and experimental demonstration of active separation control using glow discharge plasma (GDP) actuators in flow conditions simulating the LPT. The separation delay was shown to be successful, laying the foundation for further development of the technologies to practical application in the LPT. In a fluid mechanics context, the term "flow control" means a technology by which a very small input results in a very large effect on the flow. In this project, the interest is to eliminate or delay flow separation on LPT airfoils by using an active flow control approach, in which disturbances are dynamically inserted into the flow, they interact with the flow, and they delay separation. The disturbances can be inserted using a localized, externally powered, actuating device, examples are acoustic, pneumatic, or mechanical devices that generate vibrations, flow oscillations, or pulses. A variety of flow control devices have been demonstrated in recent years in the context of the external aerodynamics of aircraft wings and airframes, where the incoming flow is quiescent or of a very low turbulence level. However, the flow conditions in the LPT are significantly different because there are high levels of disturbances in the incoming flow that are characterized by high free-stream turbulence intensity. In addition, the Reynolds number, which characterizes the viscous forces in the flow and is related to the flow speed, is very low in the LPT passages.

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Floating Debris Control; A Literature Review.

DTIC Science & Technology

1987-06-01

Debris diversion boom and debris, Appalachian Power Company Station at Winfield Lock and Dam, Kanavha River, West Virginia. Than, T 9 (sin a) - 1.94...control dam. Central gate Is blocked partly open causing .ime downstream scour. Water flows right to left. BOTTOM-Debris diversion boom and debris... Appalachian Power Company Station at Winfield Lock and Dam, Kanawha River, West Virginia. - 0 .’ Unclass ified SECURITY CLASSIFICATION OF THIS PAGE for- 40

Optimal coordinated voltage control in active distribution networks using backtracking search algorithm

PubMed Central

Tengku Hashim, Tengku Juhana; Mohamed, Azah

2017-01-01

The growing interest in distributed generation (DG) in recent years has led to a number of generators connected to a distribution system. The integration of DGs in a distribution system has resulted in a network known as active distribution network due to the existence of bidirectional power flow in the system. Voltage rise issue is one of the predominantly important technical issues to be addressed when DGs exist in an active distribution network. This paper presents the application of the backtracking search algorithm (BSA), which is relatively new optimisation technique to determine the optimal settings of coordinated voltage control in a distribution system. The coordinated voltage control considers power factor, on-load tap-changer and generation curtailment control to manage voltage rise issue. A multi-objective function is formulated to minimise total losses and voltage deviation in a distribution system. The proposed BSA is compared with that of particle swarm optimisation (PSO) so as to evaluate its effectiveness in determining the optimal settings of power factor, tap-changer and percentage active power generation to be curtailed. The load flow algorithm from MATPOWER is integrated in the MATLAB environment to solve the multi-objective optimisation problem. Both the BSA and PSO optimisation techniques have been tested on a radial 13-bus distribution system and the results show that the BSA performs better than PSO by providing better fitness value and convergence rate. PMID:28991919

Optimal coordinated voltage control in active distribution networks using backtracking search algorithm.

PubMed

Tengku Hashim, Tengku Juhana; Mohamed, Azah

2017-01-01

The growing interest in distributed generation (DG) in recent years has led to a number of generators connected to a distribution system. The integration of DGs in a distribution system has resulted in a network known as active distribution network due to the existence of bidirectional power flow in the system. Voltage rise issue is one of the predominantly important technical issues to be addressed when DGs exist in an active distribution network. This paper presents the application of the backtracking search algorithm (BSA), which is relatively new optimisation technique to determine the optimal settings of coordinated voltage control in a distribution system. The coordinated voltage control considers power factor, on-load tap-changer and generation curtailment control to manage voltage rise issue. A multi-objective function is formulated to minimise total losses and voltage deviation in a distribution system. The proposed BSA is compared with that of particle swarm optimisation (PSO) so as to evaluate its effectiveness in determining the optimal settings of power factor, tap-changer and percentage active power generation to be curtailed. The load flow algorithm from MATPOWER is integrated in the MATLAB environment to solve the multi-objective optimisation problem. Both the BSA and PSO optimisation techniques have been tested on a radial 13-bus distribution system and the results show that the BSA performs better than PSO by providing better fitness value and convergence rate.

78 FR 52172 - Don W. Gilbert Hydro Power, LLC; Notice of Availability of Environmental Assessment

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-22

... kilowatts (kW) and would utilize the flow from several unnamed springs that converge into an unnamed channel... to the existing stream channel that flows into the Bear River; (5) a 150-foot-long, 480-volt... Construction Implement industry-standard erosion control measures to minimize erosion and sedimentation; Stop...

NASA F-16XL supersonic laminar flow control program overview

NASA Technical Reports Server (NTRS)

Fischer, Michael C.

1992-01-01

The viewgraphs and discussion of the NASA supersonic laminar flow control program are provided. Successful application of laminar flow control to a High Speed Civil Transport (HSCT) offers significant benefits in reductions of take-off gross weight, mission fuel burn, cruise drag, structural temperatures, engine size, emissions, and sonic boom. The ultimate economic success of the proposed HSCT may depend on the successful adaption of laminar flow control, which offers the single most significant potential improvements in lift drag ratio (L/D) of all the aerodynamic technologies under consideration. The F-16XL Supersonic Laminar Flow Control (SLFC) Experiment was conceived based on the encouraging results of in-house and NASA supported industry studies to determine if laminar flow control is feasible for the HSCT. The primary objective is to achieve extensive laminar flow (50-60 percent chord) on a highly swept supersonic wing. Data obtained from the flight test will be used to validate existing Euler and Navier Stokes aerodynamic codes and transition prediction boundary layer stability codes. These validated codes and developed design methodology will be delivered to industry for their use in designing supersonic laminar flow control wings. Results from this experiment will establish preliminary suction system design criteria enabling industry to better size the suction system and develop improved estimates of system weight, fuel volume loss due to wing ducting, turbocompressor power requirements, etc. so that benefits and penalties can be more accurately assessed.

Iodine Hall Thruster Propellant Feed System for a CubeSat

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.

2014-01-01

There has been significant work recently in the development of iodine-fed Hall thrusters for in-space propulsion applications.1 The use of iodine as a propellant provides many advantages over present xenon-gas-fed Hall thruster systems. Iodine is a solid at ambient temperature (no pressurization required) and has no special handling requirements, making it safe for secondary flight opportunities. It has exceptionally high ?I sp (density times specific impulse), making it an enabling technology for small satellite near-term applications and providing system level advantages over mid-term high power electric propulsion options. Iodine provides thrust and efficiency that are comparable to xenonfed Hall thrusters while operating in the same discharge current and voltage regime, making it possible to leverage the development of flight-qualified xenon Hall thruster power processing units for the iodine application. Work at MSFC is presently aimed at designing, integrating, and demonstrating a flight-like iodine feed system suitable for the Hall thruster application. This effort represents a significant advancement in state-of-the-art. Though Iodine thrusters have demonstrated high performance with mission enabling potential, a flight-like feed system has never been demonstrated and iodine compatible components do not yet exist. Presented in this paper is the end-to-end integrated feed system demonstration. The system includes a propellant tank with active feedback-control heating, fill and drain interfaces, latching and proportional flow control valves (PFCV), flow resistors, and flight-like CubeSat power and control electronics. Hardware is integrated into a CubeSat-sized structure, calibrated and tested under vacuum conditions, and operated under under hot-fire conditions using a Busek BHT-200 thruster designed for iodine. Performance of the system is evaluated thorugh accurate measurement of thrust and a calibrated of mass flow rate measurement, which is a function of reservoir temperature/pressure, the flow resistors, and the setting of the PFCV. The calibration is performed using independent flow control monitoring techniques, providing an in situ measure of the flowrate as a function of controllable parameters. The reservoir temperature controls the iodine sublimation rate, providing propellant to ths thruster by pressurizing the propellant feed system to approx.1-2 psi. Control of the temperature and the PFCV are used to maintain reservoir pressure and keep the thruster discharge current constant.

Fine PM measurements: personal and indoor air monitoring.

PubMed

Jantunen, M; Hänninen, O; Koistinen, K; Hashim, J H

2002-12-01

This review compiles personal and indoor microenvironment particulate matter (PM) monitoring needs from recently set research objectives, most importantly the NRC published "Research Priorities for Airborne Particulate Matter (1998)". Techniques and equipment used to monitor PM personal exposures and microenvironment concentrations and the constituents of the sampled PM during the last 20 years are then reviewed. Development objectives are set and discussed for personal and microenvironment PM samplers and monitors, for filter materials, and analytical laboratory techniques for equipment calibration, filter weighing and laboratory climate control. The progress is leading towards smaller sample flows, lighter, silent, independent (battery powered) monitors with data logging capacity to store microenvironment or activity relevant sensor data, advanced flow controls and continuous recording of the concentration. The best filters are non-hygroscopic, chemically pure and inert, and physically robust against mechanical wear. Semiautomatic and primary standard equivalent positive displacement flow meters are replacing the less accurate methods in flow calibration, and also personal sampling flow rates should become mass flow controlled (with or without volumetric compensation for pressure and temperature changes). In the weighing laboratory the alternatives are climatic control (set temperature and relative humidity), and mechanically simpler thermostatic heating, air conditioning and dehumidification systems combined with numerical control of temperature, humidity and pressure effects on flow calibration and filter weighing.

Wind Plant Power Optimization through Yaw Control using a Parametric Model for Wake Effects -- A CFD Simulation Study

DOE PAGES

Gebraad, P. M. O.; Teeuwisse, F. W.; van Wingerden, J. W.; ...

2016-01-01

This article presents a wind plant control strategy that optimizes the yaw settings of wind turbines for improved energy production of the whole wind plant by taking into account wake effects. The optimization controller is based on a novel internal parametric model for wake effects, called the FLOw Redirection and Induction in Steady-state (FLORIS) model. The FLORIS model predicts the steady-state wake locations and the effective flow velocities at each turbine, and the resulting turbine electrical energy production levels, as a function of the axial induction and the yaw angle of the different rotors. The FLORIS model has a limitedmore » number of parameters that are estimated based on turbine electrical power production data. In high-fidelity computational fluid dynamics simulations of a small wind plant, we demonstrate that the optimization control based on the FLORIS model increases the energy production of the wind plant, with a reduction of loads on the turbines as an additional effect.« less

Wireless programmable electrochemical drug delivery micropump with fully integrated electrochemical dosing sensors.

PubMed

Sheybani, Roya; Cobo, Angelica; Meng, Ellis

2015-08-01

We present a fully integrated implantable electrolysis-based micropump with incorporated EI dosing sensors. Wireless powering and data telemetry (through amplitude and frequency modulation) were utilized to achieve variable flow control and a bi-directional data link with the sensors. Wireless infusion rate control (0.14-1.04 μL/min) and dose sensing (bolus resolution of 0.55-2 μL) were each calibrated separately with the final circuit architecture and then simultaneous wireless flow control and dose sensing were demonstrated. Recombination detection using the dosing system, as well as, effects of coil separation distance and misalignment in wireless power and data transfer were studied. A custom-made normally closed spring-loaded ball check valve was designed and incorporated at the reservoir outlet to prevent backflow of fluids as a result of the reverse pressure gradient caused by recombination of electrolysis gases. Successful delivery, infusion rate control, and dose sensing were achieved in simulated brain tissue.

Microbubble-assisted optofluidic control using a photothermal waveguide

NASA Astrophysics Data System (ADS)

Cheng, YuPeng; Yang, JianXin; Li, ZongBao; Zhu, DeBin; Cai, Xiang; Hu, Xiaowen; Huang, Wen; Xing, XiaoBo

2017-10-01

A convenient and easily controllable microfluidic system was proposed based on a photothermal device. Here, graphene oxide was assembled on an optical waveguide, which could serve as a miniature heat source to generate a microbubble and to control dynamic behaviors of flow by adjusting optical power at the micrometer scale. Micro/nanoparticles were used to demonstrate the trace of fluid flow around the microbubble, which displayed the ability of the flow to capture, transmit, and rotate particles in thermal convection. Correspondingly, three-dimensional theoretical simulation combining thermodynamics with hydrodynamics analyzed the distribution of the velocity field induced by the microbubble for collection and driving of particles. Furthermore, the photothermal waveguide would be developed into a microbubble-based device in the manipulation or transmission of micro/nanoparticles.

Temperature Oscillation in a Loop Heat Pipe with Gravity Assist

NASA Technical Reports Server (NTRS)

Ku, Jentung; Garrison, Matt; Patel, Deepak; Ottenstein, Laura; Robinson, Frank

2014-01-01

ATLAS Laser Thermal Control System (LTCS) thermal vacuum testing where the condenser-radiator was placed in a vertical position, it was found that the loop heat pipe (LHP) reservoir required much more control heater power than the analytical model had predicted. The required control heater power was also higher than the liquid subcooling entering the reservoir using the measured temperatures and the calculated mass flow rate based on steady state LHP operation. This presentation describes the investigation of the LHP behaviors under a gravity assist mode with a very cold radiator sink temperature and a large thermal mass attached to the evaporator. It is concluded that gravity caused the cold liquid to drop from the condenser-radiator to the reservoir, resulting in a rapid decrease of the reservoir temperature. When the reservoir temperature was increasing, a reverse flow occurred in the liquid line, carrying warm liquid to the condenser-radiator. Both events consumed the reservoir control heater power. The fall and rise of the reservoir temperature also caused the net heat input to the evaporator to vary due to the release and storage of the sensible heat of the thermal mass. The combination of these effects led to a persistent reservoir temperature oscillation and a repeated influx of cold liquid from the condenser. This was the root cause of the extraordinary high control heater power requirement in the LTCS TV test. Without gravity assist, such a persistent temperature oscillation will not be present.

Experimental prototype of an electric elevator

NASA Astrophysics Data System (ADS)

Gaiceanu, M.; Epure, S.; Ciuta, S.

2016-08-01

The main objective is to achieve an elevator prototype powered by a three-phase voltage system via a bidirectional static power converter ac-ac with regenerating capability. In order to diminish the power size of the electric motor up to 1/3 of rated power, the elevator contains two carriages of the same weight, one serving as the payload, and the other as counterweight. Before proper operation of the static power converter, the capacitor must be charged at rated voltage via a precharge circuit. At the moment of stabilizing the DC voltage at nominal value, the AC-AC power converter can operates in the proper limits. The functions of the control structure are: the load control task, speed and torque controls. System includes transducers for current measuring, voltage sensors and encoder. As reserve power sources the hybrid battery-photovoltaic panels are used. The control voltage is modulated by implementing four types of pulse width modulations: sinusoidal, with reduced commutation, third order harmonic insertion, and the space vector modulation. Therefore, the prototype could operates with an increased efficiency, in spite of the existing ones. The experimental results confirm the well design of the chosen solution. The control solution assures bidirectional power flow control, precharge control, and load control and it is implemented on a digital signal processor. The elevator capacity is between 300-450 kg, and it is driven by using a 1.5 kW three-phase asynchronous machine.

Analysis characteristics determination of electrohydraulic control system operation to reduce the operation time of a powered roof support

NASA Astrophysics Data System (ADS)

Szurgacz, Dawid

2018-01-01

The article discusses basic functions of a powered roof support in a longwall unit. The support function is to provide safety by protecting mine workings against uncontrolled falling of rocks. The subject of the research includes the measures to shorten the time of roof support shifting. The roof support is adapted to transfer, in hazard conditions of rock mass tremors, dynamic loads caused by mining exploitation. The article presents preliminary research results on the time reduction of the unit advance to increase the extraction process and thus reduce operating costs. Conducted stand tests showed the ability to increase the flow for 3/2-way valve cartridges. The level of fluid flowing through the cartridges is adequate to control individual actuators.

Transient analysis of a molten salt central receiver (MSCR) in a solar power plant

NASA Astrophysics Data System (ADS)

Joshi, A.; Wang, C.; Akinjiola, O.; Lou, X.; Neuschaefer, C.; Quinn, J.

2016-05-01

Alstom is developing solar power tower plants utilizing molten salt as the working fluid. In solar power tower, the molten salt central receiver (MSCR) atop of the tower is constructed of banks of tubes arranged in panels creating a heat transfer surface exposed to the solar irradiation from the heliostat field. The molten salt heat transfer fluid (HTF), in this case 60/40%wt NaNO3-KNO3, flows in serpentine flow through the surface collecting sensible heat thus raising the HTF temperature from 290°C to 565°C. The hot molten salt is stored and dispatched to produce superheated steam in a steam generator, which in turn produces electricity in the steam turbine generator. The MSCR based power plant with a thermal energy storage system (TESS) is a fully dispatchable renewable power plant with a number of opportunities for operational and economic optimization. This paper presents operation and controls challenges to the MSCR and the overall power plant, and the use of dynamic model computer simulation based transient analyses applied to molten salt based solar thermal power plant. This study presents the evaluation of the current MSCR design, using a dynamic model, with emphasis on severe events affecting critical process response, such as MS temperature deviations, and recommend MSCR control design improvements based on the results. Cloud events are the scope of the transient analysis presented in this paper. The paper presents results from a comparative study to examine impacts or effects on key process variables related to controls and operation of the MSCR plant.

Noble gas storage and delivery system for ion propulsion

NASA Technical Reports Server (NTRS)

Back, Dwight Douglas (Inventor); Ramos, Charlie (Inventor)

2001-01-01

A method and system for storing and delivering a noble gas for an ion propulsion system where an adsorbent bearing a noble gas is heated within a storage vessel to desorb the noble gas which is then flowed through a pressure reduction device to a thruster assembly. The pressure and flow is controlled using a flow restrictor and low wattage heater which heats an adsorbent bed containing the noble gas propellant at low pressures. Flow rates of 5-60 sccm can be controlled to within about 0.5% or less and the required input power is generally less than 50 W. This noble gas storage and delivery system and method can be used for earth orbit satellites, and lunar or planetary space missions.

Corrective Control to Handle Forecast Uncertainty: A Chance Constrained Optimal Power Flow

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roald, Line; Misra, Sidhant; Krause, Thilo

Higher shares of electricity generation from renewable energy sources and market liberalization is increasing uncertainty in power systems operation. At the same time, operation is becoming more flexible with improved control systems and new technology such as phase shifting transformers (PSTs) and high voltage direct current connections (HVDC). Previous studies have shown that the use of corrective control in response to outages contributes to a reduction in operating cost, while maintaining N-1 security. In this work, we propose a method to extend the use of corrective control of PSTs and HVDCs to react to uncertainty. We characterize the uncertainty asmore » continuous random variables, and define the corrective control actions through affine control policies. This allows us to efficiently model control reactions to a large number of uncertainty sources. The control policies are then included in a chance constrained optimal power flow formulation, which guarantees that the system constraints are enforced with a desired probability. Lastly, by applying an analytical reformulation of the chance constraints, we obtain a second-order cone problem for which we develop an efficient solution algorithm. In a case study for the IEEE 118 bus system, we show that corrective control for uncertainty leads to a decrease in operational cost, while maintaining system security. Further, we demonstrate the scalability of the method by solving the problem for the IEEE 300 bus and the Polish system test cases.« less

Corrective Control to Handle Forecast Uncertainty: A Chance Constrained Optimal Power Flow

DOE PAGES

Roald, Line; Misra, Sidhant; Krause, Thilo; ...

2016-08-25

Higher shares of electricity generation from renewable energy sources and market liberalization is increasing uncertainty in power systems operation. At the same time, operation is becoming more flexible with improved control systems and new technology such as phase shifting transformers (PSTs) and high voltage direct current connections (HVDC). Previous studies have shown that the use of corrective control in response to outages contributes to a reduction in operating cost, while maintaining N-1 security. In this work, we propose a method to extend the use of corrective control of PSTs and HVDCs to react to uncertainty. We characterize the uncertainty asmore » continuous random variables, and define the corrective control actions through affine control policies. This allows us to efficiently model control reactions to a large number of uncertainty sources. The control policies are then included in a chance constrained optimal power flow formulation, which guarantees that the system constraints are enforced with a desired probability. Lastly, by applying an analytical reformulation of the chance constraints, we obtain a second-order cone problem for which we develop an efficient solution algorithm. In a case study for the IEEE 118 bus system, we show that corrective control for uncertainty leads to a decrease in operational cost, while maintaining system security. Further, we demonstrate the scalability of the method by solving the problem for the IEEE 300 bus and the Polish system test cases.« less

Dependence of Laminar Flow Fluctuation on Indium Composition in In0.07GaAs/GaAs Quantum Wells for 940-nm Infrared Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Kim, Dae-Kwang; Lee, Hyung-Joo; An, Won-Chan; Kim, Hong-Gun; Kwac, Lee-Ku

2018-05-01

The effect of laminar flow fluctuation on the indium composition of In0.07GaAs quantum wells was investigated in order to obtain a higher output power from infrared lighting-emitting diodes (IR-LEDs) having a 940-nm wavelength. By controlling the injection pressure, we obtained various laminar flow conditions. Through subsequent photoluminescence (PL) and X-ray diffraction (XRD) measurements, a noticeable improvement in the optical and the crystalline characteristics of the In0.07GaAs quantum wells was observed at an optimum laminar flow. This result could be attributed to a reduction of non-crystallization in InGaAs quantum wells that had their indium composition improved via the optimized laminar flow. Overall, a significantly improved output power (11.2 mW) was obtained from a 940-nm IR-LED chip fabricated at an optimum laminar flow of 500 sccm, and a remarkable increase of approximately 250% was displayed compared to a conventional chip (3.9 mW) fabricated at a laminar flow of 100 sccm.

Continuation Power Flow with Variable-Step Variable-Order Nonlinear Predictor

NASA Astrophysics Data System (ADS)

Kojima, Takayuki; Mori, Hiroyuki

This paper proposes a new continuation power flow calculation method for drawing a P-V curve in power systems. The continuation power flow calculation successively evaluates power flow solutions through changing a specified value of the power flow calculation. In recent years, power system operators are quite concerned with voltage instability due to the appearance of deregulated and competitive power markets. The continuation power flow calculation plays an important role to understand the load characteristics in a sense of static voltage instability. In this paper, a new continuation power flow with a variable-step variable-order (VSVO) nonlinear predictor is proposed. The proposed method evaluates optimal predicted points confirming with the feature of P-V curves. The proposed method is successfully applied to IEEE 118-bus and IEEE 300-bus systems.

Dissipated power and induced velocity fields data of a micro single dielectric barrier discharge plasma actuator for active flow control☆

PubMed Central

Pescini, E.; Martínez, D.S.; De Giorgi, M.G.; Francioso, L.; Ficarella, A.

2015-01-01

In recent years, single dielectric barrier discharge (SDBD) plasma actuators have gained great interest among all the active flow control devices typically employed in aerospace and turbomachinery applications [1,2]. Compared with the macro SDBDs, the micro single dielectric barrier discharge (MSDBD) actuators showed a higher efficiency in conversion of input electrical power to delivered mechanical power [3,4]. This article provides data regarding the performances of a MSDBD plasma actuator [5,6]. The power dissipation values [5] and the experimental and numerical induced velocity fields [6] are provided. The present data support and enrich the research article entitled “Optimization of micro single dielectric barrier discharge plasma actuator models based on experimental velocity and body force fields” by Pescini et al. [6]. PMID:26425667

Communications and control for electric power systems: Power flow classification for static security assessment

NASA Technical Reports Server (NTRS)

Niebur, D.; Germond, A.

1993-01-01

This report investigates the classification of power system states using an artificial neural network model, Kohonen's self-organizing feature map. The ultimate goal of this classification is to assess power system static security in real-time. Kohonen's self-organizing feature map is an unsupervised neural network which maps N-dimensional input vectors to an array of M neurons. After learning, the synaptic weight vectors exhibit a topological organization which represents the relationship between the vectors of the training set. This learning is unsupervised, which means that the number and size of the classes are not specified beforehand. In the application developed in this report, the input vectors used as the training set are generated by off-line load-flow simulations. The learning algorithm and the results of the organization are discussed.

Study on the flow in the pipelines of the support system of circulating fluidized bed

NASA Astrophysics Data System (ADS)

Meng, L.; Yang, J.; Zhou, L. J.; Wang, Z. W.; Zhuang, X. H.

2013-12-01

In the support system of Circulating Fluidized Bed (Below referred to as CFB) of thermal power plant, the pipelines of primary wind are used for transporting the cold air to the boiler, which is important in controlling and combustion effect. The pipeline design will greatly affect the energy loss of the system, and accordingly affect the thermal power plant economic benefits and production environment. Three-dimensional numerical simulation is carried out for the pipeline internal flow field of a thermal power plant in this paper. Firstly three turbulence models were compared and the results showed that the SST k-ω model converged better and the energy losses predicted were closer to the experimental results. The influence of the pipeline design form on the flow characteristics are analysed, then the optimization designs of the pipeline are proposed according to the energy loss distribution of the flow field, in order to reduce energy loss and improve the efficiency of tunnel. The optimization plan turned out to be efficacious; about 36% of the pressure loss is reduced.

Systems and methods for optimal power flow on a radial network

DOEpatents

Low, Steven H.; Peng, Qiuyu

2018-04-24

Node controllers and power distribution networks in accordance with embodiments of the invention enable distributed power control. One embodiment includes a node controller including a distributed power control application; a plurality of node operating parameters describing the operating parameter of a node and a set of at least one node selected from the group consisting of an ancestor node and at least one child node; wherein send node operating parameters to nodes in the set of at least one node; receive operating parameters from the nodes in the set of at least one node; calculate a plurality of updated node operating parameters using an iterative process to determine the updated node operating parameters using the node operating parameters that describe the operating parameters of the node and the set of at least one node, where the iterative process involves evaluation of a closed form solution; and adjust node operating parameters.

Model predictive direct power control for active power decoupled single-phase quasi- Z -source inverter

DOE PAGES

Liu, Yushan; Ge, Baoming; Abu-Rub, Haitham; ...

2016-06-14

In this study, the active power filter (APF) that consists of a half-bridge leg and an ac capacitor is integrated in the single-phase quasi-Z-source inverter (qZSI) in this paper to avoid the second harmonic power flowing into the dc side. The capacitor of APF buffers the second harmonic power of the load, and the ac capacitor allows highly pulsating ac voltage, so that the capacitances of both dc and ac sides can be small. A model predictive direct power control (DPC) is further proposed to achieve the purpose of this newtopology through predicting the capacitor voltage of APF at eachmore » sampling period and ensuring the APF power to track the second harmonic power of single-phase qZSI. Simulation and experimental results verify the model predictive DPC for the APF-integrated single-phase qZSI.« less

Model predictive direct power control for active power decoupled single-phase quasi- Z -source inverter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Liu, Yushan; Ge, Baoming; Abu-Rub, Haitham

In this study, the active power filter (APF) that consists of a half-bridge leg and an ac capacitor is integrated in the single-phase quasi-Z-source inverter (qZSI) in this paper to avoid the second harmonic power flowing into the dc side. The capacitor of APF buffers the second harmonic power of the load, and the ac capacitor allows highly pulsating ac voltage, so that the capacitances of both dc and ac sides can be small. A model predictive direct power control (DPC) is further proposed to achieve the purpose of this newtopology through predicting the capacitor voltage of APF at eachmore » sampling period and ensuring the APF power to track the second harmonic power of single-phase qZSI. Simulation and experimental results verify the model predictive DPC for the APF-integrated single-phase qZSI.« less

Power Controller

NASA Technical Reports Server (NTRS)

1982-01-01

The device called the Power Factor Controller (PFC) offers exceptional energy conservation potential by virtue of its ability to sense shifts in the relationship between voltage and current flow, and to match them with the motor's need. Originating from the solar heating/cooling program, the PFC senses a light load, it cuts the voltage level to the minimum needed which in turn reduces current flow and heat loss. Laboratory tests showed that the PFC could reduce power used by six to eight percent under normal motor loads, and as much as 65 percent when the motor was idling. Over 150 companies have been granted NASA licenses for commercial use of this technology. One system that utilizes this technology is the Vectrol Energy System, (VES) produced by Vectrol, Inc. a subsidiary of Westinghouse. The VES is being used at Woodward & Lothrop, on their escalators. Energy use is regulated according to how many people are on the escalator at any time. It is estimated that the energy savings are between 30 to 40 percent.

Ocean Current Power Generator. Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

O'Sullivan, G. A.

2002-07-26

The Ocean Power Generator is both technically and economically suitable for deployment in the Gulf Stream from the US Navy facility in Dania, Florida. Yet to be completed is the calibration test in the Chesapeake Bay with the prototype dual hydroturbine Underwater Electric Kite. For the production units a revised design includes two ballast tanks mounted as pontoons to provide buoyancy and depth control. The power rating of the Ocean Power Generator has been doubled to 200 kW ready for insertion into the utility grid. The projected cost for a 10 MW installation is $3.38 per watt, a cost thatmore » is consistent with wind power pricing when it was in its deployment infancy, and a cost that is far better than photovoltaics after 25 years of research and development. The Gulf Stream flows 24 hours per day, and water flow is both environmentally and ecologically perfect as a renewable energy source. No real estate purchases are necessary, and you cannot see, hear, smell, or touch an Ocean Power Generator.« less

A multi-mode operation control strategy for flexible microgrid based on sliding-mode direct voltage and hierarchical controls.

PubMed

Zhang, Qinjin; Liu, Yancheng; Zhao, Youtao; Wang, Ning

2016-03-01

Multi-mode operation and transient stability are two problems that significantly affect flexible microgrid (MG). This paper proposes a multi-mode operation control strategy for flexible MG based on a three-layer hierarchical structure. The proposed structure is composed of autonomous, cooperative, and scheduling controllers. Autonomous controller is utilized to control the performance of the single micro-source inverter. An adaptive sliding-mode direct voltage loop and an improved droop power loop based on virtual negative impedance are presented respectively to enhance the system disturbance-rejection performance and the power sharing accuracy. Cooperative controller, which is composed of secondary voltage/frequency control and phase synchronization control, is designed to eliminate the voltage/frequency deviations produced by the autonomous controller and prepare for grid connection. Scheduling controller manages the power flow between the MG and the grid. The MG with the improved hierarchical control scheme can achieve seamless transitions from islanded to grid-connected mode and have a good transient performance. In addition the presented work can also optimize the power quality issues and improve the load power sharing accuracy between parallel VSIs. Finally, the transient performance and effectiveness of the proposed control scheme are evaluated by theoretical analysis and simulation results. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

On the dependence of the domain of values of functionals of hypersonic aerodynamics on controls

NASA Astrophysics Data System (ADS)

Bilchenko, Grigory; Bilchenko, Nataly

2018-05-01

The properties of mathematical model of control of heat and mass transfer in laminar boundary layer on permeable cylindrical and spherical surfaces of the hypersonic aircraft are considered. Dependences of hypersonic aerodynamics functionals (the total heat flow and the total Newton friction force) on controls (the blowing into boundary layer, the temperature factor, the magnetic field) are investigated. The domains of allowed values of functionals of hypersonic aerodynamics are obtained. The results of the computational experiments are presented: the dependences of total heat flow on controls; the dependences of total Newton friction force on controls; the mutual dependences of functionals (as the domains of allowed values "Heat and Friction"); the dependences of blowing system power on controls. The influences of magnetic field and dissociation on the domain of "Heat and Friction" allowed values are studied. It is proved that for any fixed constant value of magnetic field the blowing system power is a symmetric function of constant dimensionless controls (the blowing into boundary layer and the temperature factor). It is shown that the obtained domain of allowed values of functionals of hypersonic aerodynamics depending on permissible range of controls may be used in engineering.

Development of an air flow calorimeter prototype for the measurement of thermal power released by large radioactive waste packages.

PubMed

Razouk, R; Beaumont, O; Failleau, G; Hay, B; Plumeri, S

2018-03-01

The estimation and control of the thermal power released by the radioactive waste packages are a key parameter in the management of radioactive waste geological repository sites. In the framework of the European project "Metrology for decommissioning nuclear facilities," the French National Agency of Radioactive Waste Management (ANDRA) collaborates with Laboratoire National de Métrologie et D'essais in order to measure the thermal power up to 500 W of typical real size radioactive waste packages (of at least 0.175 m 3 ) with an uncertainty better than 5% by using a measurement method traceable to the international system of units. One of the selected metrological approaches is based on the principles of air flow calorimetry. This paper describes in detail the development of the air flow calorimeter prototype as well as the design of a radioactive waste package simulator used for its calibration. Results obtained from the calibration of the calorimeter and from the determination of thermal powers are presented here with an investigation of the measurement uncertainties.

Development of an air flow calorimeter prototype for the measurement of thermal power released by large radioactive waste packages

NASA Astrophysics Data System (ADS)

Razouk, R.; Beaumont, O.; Failleau, G.; Hay, B.; Plumeri, S.

2018-03-01

The estimation and control of the thermal power released by the radioactive waste packages are a key parameter in the management of radioactive waste geological repository sites. In the framework of the European project "Metrology for decommissioning nuclear facilities," the French National Agency of Radioactive Waste Management (ANDRA) collaborates with Laboratoire National de Métrologie et D'essais in order to measure the thermal power up to 500 W of typical real size radioactive waste packages (of at least 0.175 m3) with an uncertainty better than 5% by using a measurement method traceable to the international system of units. One of the selected metrological approaches is based on the principles of air flow calorimetry. This paper describes in detail the development of the air flow calorimeter prototype as well as the design of a radioactive waste package simulator used for its calibration. Results obtained from the calibration of the calorimeter and from the determination of thermal powers are presented here with an investigation of the measurement uncertainties.

Reactor transient control in support of PFR/TREAT TUCOP experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Burrows, D.R.; Larsen, G.R.; Harrison, L.J.

1984-01-01

Unique energy deposition and experiment control requirements posed bythe PFR/TREAT series of transient undercooling/overpower (TUCOP) experiments resulted in equally unique TREAT reactor operations. New reactor control computer algorithms were written and used with the TREAT reactor control computer system to perform such functions as early power burst generation (based on test train flow conditions), burst generation produced by a step insertion of reactivity following a controlled power ramp, and shutdown (SCRAM) initiators based on both test train conditions and energy deposition. Specialized hardware was constructed to simulate test train inputs to the control computer system so that computer algorithms couldmore » be tested in real time without irradiating the experiment.« less

Dispatching power system for preventive and corrective voltage collapse problem in a deregulated power system

NASA Astrophysics Data System (ADS)

Alemadi, Nasser Ahmed

Deregulation has brought opportunities for increasing efficiency of production and delivery and reduced costs to customers. Deregulation has also bought great challenges to provide the reliability and security customers have come to expect and demand from the electrical delivery system. One of the challenges in the deregulated power system is voltage instability. Voltage instability has become the principal constraint on power system operation for many utilities. Voltage instability is a unique problem because it can produce an uncontrollable, cascading instability that results in blackout for a large region or an entire country. In this work we define a system of advanced analytical methods and tools for secure and efficient operation of the power system in the deregulated environment. The work consists of two modules; (a) contingency selection module and (b) a Security Constrained Optimization module. The contingency selection module to be used for voltage instability is the Voltage Stability Security Assessment and Diagnosis (VSSAD). VSSAD shows that each voltage control area and its reactive reserve basin describe a subsystem or agent that has a unique voltage instability problem. VSSAD identifies each such agent. VS SAD is to assess proximity to voltage instability for each agent and rank voltage instability agents for each contingency simulated. Contingency selection and ranking for each agent is also performed. Diagnosis of where, why, when, and what can be done to cure voltage instability for each equipment outage and transaction change combination that has no load flow solution is also performed. A security constrained optimization module developed solves a minimum control solvability problem. A minimum control solvability problem obtains the reactive reserves through action of voltage control devices that VSSAD determines are needed in each agent to obtain solution of the load flow. VSSAD makes a physically impossible recommendation of adding reactive generation capability to specific generators to allow a load flow solution to be obtained. The minimum control solvability problem can also obtain solution of the load flow without curtailing transactions that shed load and generation as recommended by VSSAD. A minimum control solvability problem will be implemented as a corrective control, that will achieve the above objectives by using minimum control changes. The control includes; (1) voltage setpoint on generator bus voltage terminals; (2) under load tap changer tap positions and switchable shunt capacitors; and (3) active generation at generator buses. The minimum control solvability problem uses the VSSAD recommendation to obtain the feasible stable starting point but completely eliminates the impossible or onerous recommendation made by VSSAD. This thesis reviews the capabilities of Voltage Stability Security Assessment and Diagnosis and how it can be used to implement a contingency selection module for the Open Access System Dispatch (OASYDIS). The OASYDIS will also use the corrective control computed by Security Constrained Dispatch. The corrective control would be computed off line and stored for each contingency that produces voltage instability. The control is triggered and implemented to correct the voltage instability in the agent experiencing voltage instability only after the equipment outage or operating changes predicted to produce voltage instability have occurred. The advantages and the requirements to implement the corrective control are also discussed.

Zebra Mussel Chemical Control Guide, Version 2.0

DTIC Science & Technology

2015-07-01

delivery systems, including potable water treatment, agriculture, industry, power generation, and fire protection. Since this invasive organism’s...delivery systems, including potable water treatment, agriculture, industry, power generation, and fire protection (Mackie and Claudi 2010). Zebra mussels...generators, pipes, valves, sensing equipment (level, flow, and pressure) and fire protection (Mackie and Claudi 2010; Prescott et al. 2014). Other USACE

Evidence for tectonic, lithologic, and thermal controls on fracture system geometries in an andesitic high-temperature geothermal field

NASA Astrophysics Data System (ADS)

Massiot, Cécile; Nicol, Andrew; McNamara, David D.; Townend, John

2017-08-01

Analysis of fracture orientation, spacing, and thickness from acoustic borehole televiewer (BHTV) logs and cores in the andesite-hosted Rotokawa geothermal reservoir (New Zealand) highlights potential controls on the geometry of the fracture system. Cluster analysis of fracture orientations indicates four fracture sets. Probability distributions of fracture spacing and thickness measured on BHTV logs are estimated for each fracture set, using maximum likelihood estimations applied to truncated size distributions to account for sampling bias. Fracture spacing is dominantly lognormal, though two subordinate fracture sets have a power law spacing. This difference in spacing distributions may reflect the influence of the andesitic sequence stratification (lognormal) and tectonic faults (power law). Fracture thicknesses of 9-30 mm observed in BHTV logs, and 1-3 mm in cores, are interpreted to follow a power law. Fractures in thin sections (˜5 μm thick) do not fit this power law distribution, which, together with their orientation, reflect a change of controls on fracture thickness from uniform (such as thermal) controls at thin section scale to anisotropic (tectonic) at core and BHTV scales of observation. However, the ˜5% volumetric percentage of fractures within the rock at all three scales suggests a self-similar behavior in 3-D. Power law thickness distributions potentially associated with power law fluid flow rates, and increased connectivity where fracture sets intersect, may cause the large permeability variations that occur at hundred meter scales in the reservoir. The described fracture geometries can be incorporated into fracture and flow models to explore the roles of fracture connectivity, stress, and mineral precipitation/dissolution on permeability in such andesite-hosted geothermal systems.

Preliminary design of a solar central receiver for a site-specific repowering application (Saguaro Power Plant). Volume IV. Appendixes. Final report, October 1982-September 1983

DOE Office of Scientific and Technical Information (OSTI.GOV)

Weber, E.R.

1983-09-01

The appendixes for the Saguaro Power Plant includes the following: receiver configuration selection report; cooperating modes and transitions; failure modes analysis; control system analysis; computer codes and simulation models; procurement package scope descriptions; responsibility matrix; solar system flow diagram component purpose list; thermal storage component and system test plans; solar steam generator tube-to-tubesheet weld analysis; pipeline listing; management control schedule; and system list and definitions.

Novel operation and control of an electric vehicle aluminum/air battery system

NASA Astrophysics Data System (ADS)

Zhang, Xin; Yang, Shao Hua; Knickle, Harold

The objective of this paper is to create a method to size battery subsystems for an electric vehicle to optimize battery performance. Optimization of performance includes minimizing corrosion by operating at a constant current density. These subsystems will allow for easy mechanical recharging. A proper choice of battery subsystem will allow for longer battery life, greater range and performance. For longer life, the current density and reaction rate should be nearly constant. The control method requires control of power by controlling electrolyte flow in battery sub modules. As power is increased more sub modules come on line and more electrolyte is needed. Solenoid valves open in a sequence to provide the required power. Corrosion is limited because there is no electrolyte in the modules not being used.

Computational investigation of flow control by means of tubercles on Darrieus wind turbine blades

NASA Astrophysics Data System (ADS)

Sevinç, K.; Özdamar, G.; Şentürk, U.; Özdamar, A.

2015-09-01

This work presents the current status of the computational study of the boundary layer control of a vertical axis wind turbine blade by modifying the blade geometry for use in wind energy conversion. The control method is a passive method which comprises the implementation of the tubercle geometry of a humpback whale flipper onto the leading edge of the blades. The baseline design is an H-type, three-bladed Darrieus turbine with a NACA 0015 cross-section. Finite-volume based software ANSYS Fluent was used in the simulations. Using the optimum control parameters for a NACA 634-021 profile given by Johari et al. (2006), turbine blades were modified. Three dimensional, unsteady, turbulent simulations for the blade were conducted to look for a possible improvement on the performance. The flow structure on the blades was investigated and flow phenomena such as separation and stall were examined to understand their impact on the overall performance. For a tip speed ratio of 2.12, good agreement was obtained in the validation of the baseline model with a relative error in time- averaged power coefficient of 1.05%. Modified turbine simulations with a less expensive but less accurate turbulence model yielded a decrease in power coefficient. Results are shown comparatively.

Experimental study on the 300W class planar type solid oxide fuel cell stack: Investigation for appropriate fuel provision control and the transient capability of the cell performance

NASA Astrophysics Data System (ADS)

Komatsu, Y.; Brus, G.; Kimijima, S.; Szmyd, J. S.

2012-11-01

The present paper reports the experimental study on the dynamic behavior of a solid oxide fuel cell (SOFC). The cell stack consists of planar type cells with standard power output 300W. A Major subject of the present study is characterization of the transient response to the electric current change, assuming load-following operation. The present studies particularly focus on fuel provision control to the load change. Optimized fuel provision improves power generation efficiency. However, the capability of SOFC must be restricted by a few operative parameters. Fuel utilization factor, which is defined as the ratio of the consumed fuel to the supplied fuel is adopted for a reference in the control scheme. The fuel flow rate was regulated to keep the fuel utilization at 50%, 60% and 70% during the current ramping. Lower voltage was observed with the higher fuel utilization, but achieved efficiency was higher. The appropriate mass flow control is required not to violate the voltage transient behavior. Appropriate fuel flow manipulation can contribute to moderate the overshoot on the voltage that may appear to the current change. The overshoot on the voltage response resulted from the gradual temperature behavior in the SOFC stack module.

Numerical Simulation of a High-Lift Configuration with Embedded Fluidic Actuators

NASA Technical Reports Server (NTRS)

Vatsa, Veer N.; Casalino, Damiano; Lin, John C.; Appelbaum, Jason

2014-01-01

Numerical simulations have been performed for a vertical tail configuration with deflected rudder. The suction surface of the main element of this configuration is embedded with an array of 32 fluidic actuators that produce oscillating sweeping jets. Such oscillating jets have been found to be very effective for flow control applications in the past. In the current paper, a high-fidelity computational fluid dynamics (CFD) code known as the PowerFLOW(Registered TradeMark) code is used to simulate the entire flow field associated with this configuration, including the flow inside the actuators. The computed results for the surface pressure and integrated forces compare favorably with measured data. In addition, numerical solutions predict the correct trends in forces with active flow control compared to the no control case. Effect of varying yaw and rudder deflection angles are also presented. In addition, computations have been performed at a higher Reynolds number to assess the performance of fluidic actuators at flight conditions.

An overview of active flow control actuators and applications (presentation video)

NASA Astrophysics Data System (ADS)

Brzozowski, Daniel; Whalen, Edward A.

2014-04-01

Active Flow Control (AFC) is an emerging technology which promises performance enhancements to both military and civilian aircraft. A technique which uses energy input at discrete locations to manipulate the flow over an aerodynamic surface, AFC may be used to reduce drag, prevent flow separation, and enable otherwise-infeasible aerodynamic designs. Additional applications include shear layer and turbulence control for aero-optics applications and mixing enhancement for thermal applications. Many AFC applications call for a high frequency fluidic perturbation provided by an electrically-powered actuator. In these instances, piezoelectric (PZT) materials have served as the workhorse for flow control actuators, such as the widely-studied synthetic jet. Because the PZT materials form the critical component of the actuator, the maximum performance of the synthetic jet (velocity and momentum output) is limited by the physical limitations of the PZT material. The purpose of this presentation is to provide a high level overview of AFC actuators and applications in an attempt to engage the smart materials community and encourage advanced material development in support of these crucial applications.

Modern control techniques in active flutter suppression using a control moment gyro

NASA Technical Reports Server (NTRS)

Buchek, P. M.

1974-01-01

Development of organized synthesis techniques, using concepts of modern control theory was studied for the design of active flutter suppression systems for two and three-dimensional lifting surfaces, utilizing a control moment gyro (CMG) to generate the required control torques. Incompressible flow theory is assumed, with the unsteady aerodynamic forces and moments for arbitrary airfoil motion obtained by using the convolution integral based on Wagner's indicial lift function. Linear optimal control theory is applied to find particular optimal sets of gain values which minimize a quadratic performance function. The closed loop system's response to impulsive gust disturbances and the resulting control power requirements are investigated, and the system eigenvalues necessary to minimize the maximum value of control power are determined.

Reverse matrix converter control method for PMSM drives using DPC

NASA Astrophysics Data System (ADS)

Bak, Yeongsu; Lee, Kyo-Beum

2018-05-01

This paper proposes a control method for a reverse matrix converter (RMC) that drives a three-phase permanent magnet synchronous motor (PMSM). In this proposed method, direct power control (DPC) is used to control the voltage source rectifier of the RMC. The RMC is an indirect matrix converter operating in the boost mode, in which the power-flow directions of the input and output are switched. It has a minimum voltage transfer ratio of 1/0.866 in a linear-modulation region. In this paper, a control method that uses DPC as an additional control method is proposed in order to control the RMC driving a PMSM in the output stage. Simulations and experimental results verify the effectiveness of the proposed control method.

Frequency response of the renal vasculature in congestive heart failure.

PubMed

DiBona, Gerald F; Sawin, Linda L

2003-04-29

The renal vasoconstrictor response to renal nerve stimulation is greater in congestive heart failure (CHF) rats than in control rats. This study tested the hypothesis that the enhanced renal vasoconstrictor response to renal nerve stimulation in CHF is a result of an impairment in the low-pass filter function of the renal vasculature. In response to conventional graded-frequency renal nerve stimulation, the reductions in renal blood flow at each stimulation frequency were greater in CHF rats than control rats. A pseudorandom binary sequence pattern of renal nerve stimulation was used to examine the frequency response of the renal vasculature. Although this did not affect the renal blood flow power spectrum in control rats, there was a 10-fold increase in renal blood flow power over the frequency range of 0.01 to 1.0 Hz in CHF rats. On analysis of transfer function gain, attenuation of the renal nerve stimulation input signal was similar in control and CHF rats over the frequency range of 0.001 to 0.1 Hz. However, over the frequency range of 0.1 to 1.0 Hz, although there was progressive attenuation of the input signal (-30 to -70 dB) in control rats, CHF rats exhibited a flat gain response (-20 dB) without progressive attenuation. The enhanced renal vasoconstrictor response to renal nerve stimulation in CHF rats is caused by an alteration in the low-pass filter function of the renal vasculature, resulting in a greater transfer of input signals into renal blood flow in the 0.1 to 1.0 Hz range.

Power systems and requirements for the integration of smart structures into aircraft

NASA Astrophysics Data System (ADS)

Lockyer, Allen J.; Martin, Christopher A.; Lindner, Douglas K.; Walia, Paramjit S.

2002-07-01

Electrical power distribution for recently developed smart actuators becomes an important air-vehicle challenge if projected smart actuation benefits are to be met. Among the items under development are variable shape inlets and control surfaces that utilize shape memory alloys (SMA); full span, chord-wise and span-wise contouring trailing control surfaces that use SMA or piezoelectric materials for actuation; and other strain-based actuators for buffet load alleviation, flutter suppression and flow control. At first glance, such technologies afford overall vehicle performance improvement, however, integration system impacts have yet to be determined or quantified. Power systems to support smart structures initiatives are the focus of the current paper. The paper has been organized into five main topics for further discussion: (1) air-vehicle power system architectures - standard and advanced distribution concepts for actuators, (2) smart wing actuator power requirements and results - highlighting wind tunnel power measurements from shape memory alloy and piezoelectric ultrasonic motor actuated control surfaces and different dynamic pressure and angle of attack; (3) vehicle electromagnetic effects (EME) issues, (4) power supply design considerations for smart actuators - featuring the aircraft power and actuator interface, and (5) summary and conclusions.

Effects of bleed air extraction on thrust levels on the F404-GE-400 turbofan engine

NASA Technical Reports Server (NTRS)

Yuhas, Andrew J.; Ray, Ronald J.

1992-01-01

A ground test was performed to determine the effects of compressor bleed flow extraction on the performance of F404-GE-400 afterburning turbofan engines. The two engines were installed in the F/A-18 High Alpha Research Vehicle at the NASA Dryden Flight Research Facility. A specialized bleed ducting system was installed onto the aircraft to control and measure engine bleed airflow while the aircraft was tied down to a thrust measuring stand. The test was conducted on each engine and at various power settings. The bleed air extraction levels analyzed included flow rates above the manufacturer's maximum specification limit. The measured relationship between thrust and bleed flow extraction was shown to be essentially linear at all power settings with an increase in bleed flow causing a corresponding decrease in thrust. A comparison with the F404-GE-400 steady-state engine simulation showed the estimation to be within +/- 1 percent of measured thrust losses for large increases in bleed flow rate.

A lab-in-a-droplet bioassay strategy for centrifugal microfluidics with density difference pumping, power to disc and bidirectional flow control.

PubMed

Wang, Guanghui; Ho, Ho-Pui; Chen, Qiulan; Yang, Alice Kar-Lai; Kwok, Ho-Chin; Wu, Shu-Yuen; Kong, Siu-Kai; Kwan, Yiu-Wa; Zhang, Xuping

2013-09-21

In this paper, we present a lab-in-a-droplet bioassay strategy for a centrifugal microfluidics or lab-on-a-disc (LOAD) platform with three important advancements including density difference pumping, power to disc and bidirectional flow control. First, with the water based bioassay droplets trapped in a micro-channel filled with mineral oil, centrifugal force due to the density difference between the water and oil phases actuates droplet movement while the oil based medium remains stationary. Second, electricity is coupled to the rotating disc through a split-core transformer, thus enabling on-chip real-time heating in selected areas as desired and wireless programmable functionality. Third, an inertial mechanical structure is proposed to achieve bidirectional flow control within the spinning disc. The droplets can move back and forth between two heaters upon changing the rotational speed. Our platform is an essential and versatile solution for bioassays such as those involving DNA amplification, where localized temperature cycling is required. Finally, without the loss of generality, we demonstrate the functionality of our platform by performing real-time polymerase chain reaction (RT-PCR) in a linear microchannel made with PTFE (Teflon) micro-tubing.

Development of a 13 kW Hall Thruster Propulsion System Performance Model for AEPS

NASA Technical Reports Server (NTRS)

Stanley, Steven; Allen, May; Goodfellow, Keith; Chew, Gilbert; Rapetti, Ryan; Tofil, Todd; Herman, Dan; Jackson, Jerry; Myers, Roger

2017-01-01

The Advanced Electric Propulsion System (AEPS) program will develop a flight 13kW Hall thruster propulsion system based on NASA's HERMeS thruster. The AEPS system includes the Hall Thruster, the Power Processing Unit (PPU) and the Xenon Flow Controller (XFC). These three primary components must operate together to ensure that the system generates the required combinations of thrust and specific impulse at the required system efficiencies for the desired system lifetime. At the highest level, the AEPS system will be integrated into the spacecraft and will receive power, propellant, and commands from the spacecraft. Power and propellant flow rates will be determined by the throttle set points commanded by the spacecraft. Within the system, the major control loop is between the mass flow rate and thruster current, with time-dependencies required to handle all expected transients, and additional, much slower interactions between the thruster and cathode temperatures, flow controller and PPU. The internal system interactions generally occur on shorter timescales than the spacecraft interactions, though certain failure modes may require rapid responses from the spacecraft. The AEPS system performance model is designed to account for all these interactions in a way that allows evaluation of the sensitivity of the system to expected changes over the planned mission as well as to assess the impacts of normal component and assembly variability during the production phase of the program. This effort describes the plan for the system performance model development, correlation to NASA test data, and how the model will be used to evaluate the critical internal and external interactions. The results will ensure the component requirements do not unnecessarily drive the system cost or overly constrain the development program. Finally, the model will be available to quickly troubleshoot any future unforeseen development challenges.

Integrated Liquid Bismuth Propellant Feed System

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Markusic, Thomas E.; Stanojev, Boris J.

2006-01-01

A prototype bismuth propellant feed and control system was constructed and tested. An electromagnetic pump was used in this system to provide fine control of the hydrostatic pressure, and a new type of in-line flow sensor was developed to provide an accurate, real-time measurement of the mass flow rate. High-temperature material compatibility was a driving design requirement for the pump and flow sensor, leading to the selection of macor for the main body of both components. Post-test inspections of both components revealed no cracks or leaking in either. In separate proof-of-concept experiments, the pump produced a linear pressure rise as a function of current that compared favorably with theoretical pump pressure predictions, with a pressure of 10 kPa at 30 A. Flow sensing was successfully demonstrated in a bench-top test using gallium as a substitute liquid metal. A real-time controller was successfully used to control the entire system, simultaneously monitoring all power supplies and performing data acquisition duties.

How shear increments affect the flow production branching ratio in CSDX

NASA Astrophysics Data System (ADS)

Li, J. C.; Diamond, P. H.

2018-06-01

The coupling of turbulence-driven azimuthal and axial flows in a linear device absent magnetic shear (Controlled Shear Decorrelation Experiment) is investigated. In particular, we examine the apportionment of Reynolds power between azimuthal and axial flows, and how the azimuthal flow shear affects axial flow generation and saturation by drift wave turbulence. We study the response of the energy branching ratio, i.e., ratio of axial and azimuthal Reynolds powers, PzR/PyR , to incremental changes of azimuthal and axial flow shears. We show that increasing azimuthal flow shear decreases the energy branching ratio. When axial flow shear increases, this ratio first increases but then decreases to zero. The axial flow shear saturates below the threshold for parallel shear flow instability. The effects of azimuthal flow shear on the generation and saturation of intrinsic axial flows are analyzed. Azimuthal flow shear slows down the modulational growth of the seed axial flow shear, and thus reduces intrinsic axial flow production. Azimuthal flow shear reduces both the residual Reynolds stress (of axial flow, i.e., ΠxzR e s ) and turbulent viscosity ( χzDW ) by the same factor |⟨vy⟩'|-2Δx-2Ln-2ρs2cs2 , where Δx is the distance relative to the reference point where ⟨vy⟩=0 in the plasma frame. Therefore, the stationary state axial flow shear is not affected by azimuthal flow shear to leading order since ⟨vz⟩'˜ΠxzR e s/χzDW .

Modeling of Autovariator Operation as Power Components Adjuster in Adaptive Machine Drives

NASA Astrophysics Data System (ADS)

Balakin, P. D.; Belkov, V. N.; Shtripling, L. O.

2018-01-01

Full application of the available power and stationary mode preservation for the power station (engine) operation of the transport machine under the conditions of variable external loading, are topical issues. The issues solution is possible by means of mechanical drives with the autovaried rate transfer function and nonholonomic constraint of the main driving mediums. Additional to the main motion, controlled motion of the driving mediums is formed by a variable part of the transformed power flow and is implemented by the integrated control loop, functioning only on the basis of the laws of motion. The mathematical model of the mechanical autovariator operation is developed using Gibbs function, acceleration energy; the study results are presented; on their basis, the design calculations of the autovariator driving mediums and constraints, including its automatic control loop, are possible.

Power console development for NASA's electric propulsion outreach program

NASA Technical Reports Server (NTRS)

Pinero, Luis R.; Patterson, Michael J.; Satterwhite, Vincent E.

1993-01-01

NASA LeRC is developing a 30 cm diameter xenon ion thruster for auxiliary and primary propulsion applications. To maximize expectations for user-acceptance of ion propulsion technology, NASA LeRC, through their Electric Propulsion Outreach Program, is providing sectors of industry with portable power consoles for operation of 5 KW-class xenon ion thrusters. This power console provides all necessary functions to permit thruster operations over a 0.5-5 KW envelope under both manual and automated control. These functions include the following: discharge, cathode heater, neutralizer keeper, and neutralizer heater currents, screen and accelerator voltages, and a gas feed system to regulate and control propellant flow to the thruster. An electronic circuit monitors screen and accelerator currents and controls arcing events. The power console was successfully integrated with the NASA 30 cm thruster.

On the use of an Arduino-based controller to control the charging process of a wind turbine

NASA Astrophysics Data System (ADS)

Mahmuddin, Faisal; Yusran, Ahmad Muhtam; Klara, Syerly

2017-02-01

In order to avoid an excessive charging voltage which can damage power storage when converting wind energy using a turbine, it is necessary to control the charging voltage of the turbine generator. In the present study, a charging controller which uses an Arduino microcontroller, is designed. 3 (three) indicator lights are installed to indicate the battery charging process, power diversion to dummy load and battery power level. The performance of the designed controller is evaluated by simulating 3 cases. In this simulation, a battery with maximum voltage of 12.4 V is used. Case 1 is performed with input voltage equals the one set in Arduino which is 10 V. In this case, the battery is charged up to 10.8 V. In case 2, the input voltage is 13 V while the maximum voltage set in Arduino is also 13 V. In this case, the battery is charged up to maximum voltage of the battery. Moreover, the dummy load indicator is ON and charging indicator is OFF after the maximum charging voltage is reached because the electricity is flowed to the dummy load. In the final case, the input voltage is set to be 16 V while the maximum voltage set in Arduino is 13 V. In this case, the charging indicator is OFF and dummy load indicator is ON which means that the Arduino has successfully switched the power to be flowed to dummy load. From the 3 (three) cases, it can be concluded that the designed controller works perfectly to control the charging process of the wind turbine. Moreover, the charging time needed in each case can also be determined.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lagier, B.; Rousset, B.; Hoa, C.

Superconducting magnets used in tokamaks undergo periodic heat load caused by cycling plasma operations inducing AC losses, neutrons fluxes and eddy currents in magnet structures. In the cryogenic system of JT60-SA tokamak, the Auxiliary Cold Box (ACB) distributes helium from the refrigerator to the cryogenic users and in particular to the superconducting magnets. ACB comprises a saturated helium bath with immersed heat exchangers, extracting heat from independent cooling loops. The supercritical helium flow in each cooling loop is driven by a cold circulator. In order to safely operate the refrigerator during plasma pulses, the interface between the ACB and themore » refrigerator shall be as stable as possible, with well-balanced bath inlet and outlet mass flows during cycling operation. The solution presented in this paper relies on a combination of regulations to smooth pulsed heat loads and to keep a constant refrigeration power during all the cycle. Two smoothing strategies are presented, both regulating the outlet mass flow of the bath: the first one using the bath as a thermal buffer and the second one storing energy in the loop by varying the cold circulator speed. The bath outlet mass flow is also controlled by an immersed resistive heater which enables a constant evaporation rate in the bath when power coming from the loops is decreasing. The refrigeration power is controlled so that the compensating power remains within an acceptable margin. Experimental validation is achieved using the HELIOS facility. This facility running at CEA Grenoble since 2010 is a scaled down model of the ACB bath and Central Solenoid magnet cooling loop of the JT60-SA tokamak. Test results show performances and robustness of the regulations.« less

Enhancement of laser power-efficiency by control of spatial hole burning interactions

NASA Astrophysics Data System (ADS)

Ge, Li; Malik, Omer; Türeci, Hakan E.

2014-11-01

The laser is an out-of-equilibrium nonlinear wave system where the interplay of the cavity geometry and nonlinear wave interactions mediated by the gain medium determines the self-organized oscillation frequencies and the associated spatial field patterns. In the steady state, a constant energy flux flows through the laser from the pump to the far field, with the ratio of the total output power to the input power determining the power-efficiency. Although nonlinear wave interactions have been modelled and well understood since the early days of laser theory, their impact on the power-efficiency of a laser system is poorly understood. Here, we show that spatial hole burning interactions generally decrease the power-efficiency. We then demonstrate how spatial hole burning interactions can be controlled by a spatially tailored pump profile, thereby boosting the power-efficiency, in some cases by orders of magnitude.

Investigation of natural circulation instability and transients in passively safe novel modular reactor

NASA Astrophysics Data System (ADS)

Shi, Shanbin

The Purdue Novel Modular Reactor (NMR) is a new type small modular reactor (SMR) that belongs to the design of boiling water reactor (BWR). Specifically, the NMR is one third the height and area of a conventional BWR reactor pressure vessel (RPV) with an electric output of 50 MWe. The fuel cycle length of the NMR-50 is extended up to 10 years due to optimized neutronics design. The NMR-50 is designed with double passive engineering safety system. However, natural circulation BWRs (NCBWR) could experience certain operational difficulties due to flow instabilities that occur at low pressure and low power conditions. Static instabilities (i.e. flow excursion (Ledinegg) instability and flow pattern transition instability) and dynamic instabilities (i.e. density wave instability and flashing/condensation instability) pose a significant challenge in two-phase natural circulation systems. In order to experimentally study the natural circulation flow instability, a proper scaling methodology is needed to build a reduced-size test facility. The scaling analysis of the NMR uses a three-level scaling method, which was developed and applied for the design of the Purdue Multi-dimensional Integral Test Assembly (PUMA). Scaling criteria is derived from dimensionless field equations and constitutive equations. The scaling process is validated by the RELAP5 analysis for both steady state and startup transients. A new well-scaled natural circulation test facility is designed and constructed based on the scaling analysis of the NMR-50. The experimental facility is installed with different equipment to measure various thermal-hydraulic parameters such as pressure, temperature, mass flow rate and void fraction. Characterization tests are performed before the startup transient tests and quasi-steady tests to determine the loop flow resistance. The controlling system and data acquisition system are programmed with LabVIEW to realize the real-time control and data storage. The thermal-hydraulic and nuclear coupled startup transients are performed to investigate the flow instabilities at low pressure and low power conditions. Two different power ramps are chosen to study the effect of power density on the flow instability. The experimental startup transient tests show the existence of three different flow instability mechanisms during the low pressure startup transients, i.e., flashing instability, condensation induced instability, and density wave oscillations. Flashing instability in the chimney section of the test loop and density wave oscillation are the main flow instabilities observed when the system pressure is below 0.5 MPa. They show completely different type of oscillations, i.e., intermittent oscillation and sinusoidal oscillation, in void fraction profile during the startup transients. In order to perform nuclear-coupled startup transients with void reactivity feedback, the Point Kinetics model is utilized to calculate the transient power during the startup transients. In addition, the differences between the electric resistance heaters and typical fuel element are taken into account. The reactor power calculated shows some oscillations due to flashing instability during the transients. However, the void reactivity feedback does not have significant influence on the flow instability during the startup procedure for the NMR-50. Further investigation of very small power ramp on the startup transients is carried out for the thermal-hydraulic startup transients. It is found that very small power density can eliminate the flashing oscillation in the single phase natural circulation and stabilize the flow oscillations in the phase of net vapor generation. Furthermore, initially pressurized startup procedure is investigated to eliminate the main flow instabilities. The results show that the pressurized startup procedure can suppress the flashing instability at low pressure and low power conditions. In order to have a deep understanding of natural circulation flow instability, the quasi-steady tests are performed using the test facility installed with preheater and subcooler. The effects of system pressure, core inlet subcooling, core power density, inlet flow resistance coefficient, and void reactivity feedback are investigated in the quasi-steady state tests. The stability boundaries are determined between unstable and stable flow conditions in the dimensionless stability plane of inlet subcooling number and Zuber number. In order to predict the stability boundary theoretically, linear stability analysis in the frequency domain is performed at four sections of the loop. The flashing in the chimney is considered as an axially uniform heat source. The dimensionless characteristic equation of the pressure drop perturbation is obtained by considering the void fraction effect and outlet flow resistance in the chimney section. The flashing boundary shows some discrepancies with previous experimental data from the quasi-steady state tests. In the future, thermal non-equilibrium is recommended to improve the accuracy of flashing instability boundary.

Optofluidic control of axonal guidance

NASA Astrophysics Data System (ADS)

Gu, Ling; Ordonez, Simon; Black, Bryan; Mohanty, Samarendra K.

2013-03-01

Significant efforts are being made for control on axonal guidance due to its importance in nerve regeneration and in the formation of functional neuronal circuitry in-vitro. These include several physical (topographic modification, optical force, and electric field), chemical (surface functionalization cues) and hybrid (electro-chemical, photochemical etc) methods. Here, we report comparison of the effect of linear flow versus microfluidic flow produced by an opticallydriven micromotor in guiding retinal ganglion axons. A circularly polarized laser tweezers was used to hold, position and spin birefringent calcite particle near growth cone, which in turn resulted in microfluidic flow. The flow rate and resulting shear-force on axons could be controlled by a varying the power of the laser tweezers beam. The calcite particles were placed separately in one chamber and single particle was transported through microfluidic channel to another chamber containing the retina explant. In presence of flow, the turning of axons was found to strongly correlate with the direction of flow. Turning angle as high as 90° was achieved. Optofluidic-manipulation can be applied to other types of mammalian neurons and also can be extended to stimulate mechano-sensing neurons.

Compact and Integrated Liquid Bismuth Propellant Feed System

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Stanojev, Boris; Korman, Valentin; Gross, Jeffrey T.

2007-01-01

Operation of Hall thrusters with bismuth propellant has been shown to be a promising path toward high-power, high-performance, long-lifetime electric propulsion for spaceflight missions [1]. There has been considerable effort in the past three years aimed at resuscitating this promising technology and validating earlier experimental results indicating the advantages of a bismuth-fed Hall thruster. A critical element of the present effort is the precise metering of propellant to the thruster, since performance cannot be accurately assessed without an accurate accounting of mass flow rate. Earlier work used a pre./post-test propellant weighing scheme that did not provide any real-time measurement of mass flow rate while the thruster was firing, and makes subsequent performance calculations difficult. The motivation of the present work is to develop a precision liquid bismuth Propellant Management System (PMS) that provides hot, molten bismuth to the thruster while simultaneously monitoring in real-time the propellant mass flow rate. The system is a derivative of our previous propellant feed system [2], but the present system represents a more compact design. In addition, all control electronics are integrated into a single unit and designed to reside on a thrust stand and operate in the relevant vacuum environment where the thruster is operating, significantly increasing the present technology readiness level of liquid metal propellant feed systems. The design of various critical components in a bismuth PMS are described. These include the bismuth reservoir and pressurization system, 'hotspot' flow sensor, power system and integrated control system. Particular emphasis is given to selection of the electronics employed in this system and the methods that were used to isolate the power and control systems from the high-temperature portions of the feed system and thruster. Open loop calibration test results from the 'hotspot' flow sensor are reported, and results of integrated thruster/PMS tests demonstrate operation of the feed system in the relevant environment.

Computational simulations of supersonic magnetohydrodynamic flow control, power and propulsion systems

NASA Astrophysics Data System (ADS)

Wan, Tian

This work is motivated by the lack of fully coupled computational tool that solves successfully the turbulent chemically reacting Navier-Stokes equation, the electron energy conservation equation and the electric current Poisson equation. In the present work, the abovementioned equations are solved in a fully coupled manner using fully implicit parallel GMRES methods. The system of Navier-Stokes equations are solved using a GMRES method with combined Schwarz and ILU(0) preconditioners. The electron energy equation and the electric current Poisson equation are solved using a GMRES method with combined SOR and Jacobi preconditioners. The fully coupled method has also been implemented successfully in an unstructured solver, US3D, and convergence test results were presented. This new method is shown two to five times faster than the original DPLR method. The Poisson solver is validated with analytic test problems. Then, four problems are selected; two of them are computed to explore the possibility of onboard MHD control and power generation, and the other two are simulation of experiments. First, the possibility of onboard reentry shock control by a magnetic field is explored. As part of a previous project, MHD power generation onboard a re-entry vehicle is also simulated. Then, the MHD acceleration experiments conducted at NASA Ames research center are simulated. Lastly, the MHD power generation experiments known as the HVEPS project are simulated. For code validation, the scramjet experiments at University of Queensland are simulated first. The generator section of the HVEPS test facility is computed then. The main conclusion is that the computational tool is accurate for different types of problems and flow conditions, and its accuracy and efficiency are necessary when the flow complexity increases.

Vertical axis wind turbine power regulation through centrifugally pumped lift spoiling

NASA Astrophysics Data System (ADS)

Klimas, P. C.; Sladky, J. F., Jr.

This paper describes an approach for lowering the rated windspeeds of Darrieus-type vertical axis wind turbines (VAWTs) whose blades are hollow aluminum extrusions. The blades, which when rotating act as centrifugal pumps, are fitted with a series of small perforations distributed along a portion of the blades' span. By valving the ends of the hollow blades, flow into the blade ends and out of the perforations may be controlled. This flow can induce premature aerodynamic stall on the blade elements, thereby reducing both the rated power of the turbine and its cost-of-energy. The concept has been proven on the Sandia National Laboratories 5-m diameter research VAWT and force balance and flow visualization wind tunnel tests have been conducted using a blade section designed for the VAWT application.

Power flows and Mechanical Intensities in structural finite element analysis

NASA Technical Reports Server (NTRS)

Hambric, Stephen A.

1989-01-01

The identification of power flow paths in dynamically loaded structures is an important, but currently unavailable, capability for the finite element analyst. For this reason, methods for calculating power flows and mechanical intensities in finite element models are developed here. Formulations for calculating input and output powers, power flows, mechanical intensities, and power dissipations for beam, plate, and solid element types are derived. NASTRAN is used to calculate the required velocity, force, and stress results of an analysis, which a post-processor then uses to calculate power flow quantities. The SDRC I-deas Supertab module is used to view the final results. Test models include a simple truss and a beam-stiffened cantilever plate. Both test cases showed reasonable power flow fields over low to medium frequencies, with accurate power balances. Future work will include testing with more complex models, developing an interactive graphics program to view easily and efficiently the analysis results, applying shape optimization methods to the problem with power flow variables as design constraints, and adding the power flow capability to NASTRAN.

Fluidics and heat generation of Alcon Infiniti and Legacy, Bausch & Lomb Millennium, and advanced medical optics sovereign phacoemulsification systems.

PubMed

Floyd, Michael S; Valentine, Jeremy R; Olson, Randall J

2006-09-01

To study heat generation, vacuum, and flow characteristics of the Alcon Infiniti and Bausch & Lomb Millennium with results compared with the Alcon Legacy and advanced medical optics (AMO) Sovereign machines previously studied. Experimental study. Heat generation with continuous ultrasound was determined with and without a 200-g weight. Flow and vacuum were determined from 12 to 40-ml/min in 2-ml/min steps. The impact of a STAAR Cruise Control was also tested. Millennium created the most heat/20% of power (5.67 +/- 0.51 degrees C unweighted and 6.80 +/- 0.80 degrees C weighted), followed by Sovereign (4.59 +/- 0.70 degrees C unweighted and 5.65 +/- 0.72 degrees C weighted), Infiniti (2.79 +/- 0.62 degrees C unweighted and 3.96 +/- 0.31 degrees C weighted), and Legacy (1.99 +/- 0.49 degrees C unweighted and 4.27 +/- 0.76 degrees C weighted; P < .0001 for all comparisons between machines except Infiniti vs Legacy, both weighted). Flow studies revealed that Millennium Peristaltic was 17% less than indicated (P < .0001 to all other machines), and all other machines were within 3.5% of indicated. Cruise Control decreased flow by 4.1% (P < .0001 for same machine without it). Millennium Venturi had the greatest vacuum (81% more than the least Sovereign; P < .0001), and Cruise Control increased vacuum in a peristaltic machine 35% more than the Venturi system (P < .0001). Percent power is not consistent in regard to heat generation, however, flow was accurate for all machines except Millennium Peristaltic. Restriction with Cruise Control elevates unoccluded vacuum to levels greater than the Venturi system tested.

Self-powered enzyme micropumps

NASA Astrophysics Data System (ADS)

Sengupta, Samudra; Patra, Debabrata; Ortiz-Rivera, Isamar; Agrawal, Arjun; Shklyaev, Sergey; Dey, Krishna K.; Córdova-Figueroa, Ubaldo; Mallouk, Thomas E.; Sen, Ayusman

2014-05-01

Non-mechanical nano- and microscale pumps that function without the aid of an external power source and provide precise control over the flow rate in response to specific signals are needed for the development of new autonomous nano- and microscale systems. Here we show that surface-immobilized enzymes that are independent of adenosine triphosphate function as self-powered micropumps in the presence of their respective substrates. In the four cases studied (catalase, lipase, urease and glucose oxidase), the flow is driven by a gradient in fluid density generated by the enzymatic reaction. The pumping velocity increases with increasing substrate concentration and reaction rate. These rechargeable pumps can be triggered by the presence of specific analytes, which enables the design of enzyme-based devices that act both as sensor and pump. Finally, we show proof-of-concept enzyme-powered devices that autonomously deliver small molecules and proteins in response to specific chemical stimuli, including the release of insulin in response to glucose.

Operation of Direct Drive Systems: Experiments in Peak Power Tracking and Multi-Thruster Control

NASA Technical Reports Server (NTRS)

Snyder, John Steven; Brophy, John R.

2013-01-01

Direct-drive power and propulsion systems have the potential to significantly reduce the mass of high-power solar electric propulsion spacecraft, among other advantages. Recent experimental direct-drive work has significantly mitigated or retired the technical risks associated with single-thruster operation, so attention is now moving toward systems-level areas of interest. One of those areas is the use of a Hall thruster system as a peak power tracker to fully use the available power from a solar array. A simple and elegant control based on the incremental conductance method, enhanced by combining it with the unique properties of Hall thruster systems, is derived here and it is shown to track peak solar array power very well. Another area of interest is multi-thruster operation and control. Dualthruster operation was investigated in a parallel electrical configuration, with both thrusters operating from discharge power provided by a single solar array. Startup and shutdown sequences are discussed, and it is shown that multi-thruster operation and control is as simple as for a single thruster. Some system architectures require operation of multiple cathodes while they are electrically connected together. Four different methods to control the discharge current emitted by individual cathodes in this configuration are investigated, with cathode flow rate control appearing to be advantageous. Dual-parallel thruster operation with equal cathode current sharing at total powers up to 10 kW is presented.

Integrative energy-systems design: System structure from thermodynamic optimization

NASA Astrophysics Data System (ADS)

Ordonez, Juan Carlos

This thesis deals with the application of thermodynamic optimization to find optimal structure and operation conditions of energy systems. Chapter 1 outlines the thermodynamic optimization of a combined power and refrigeration system subject to constraints. It is shown that the thermodynamic optimum is reached by distributing optimally the heat exchanger inventory. Chapter 2 considers the maximization of power extraction from a hot stream in the presence of phase change. It shows that when the receiving (cold) stream boils in a counterflow heat exchanger, the thermodynamic optimization consists of locating the optimal capacity rate of the cold stream. Chapter 3 shows that the main architectural features of a counterflow heat exchanger can be determined based on thermodynamic optimization subject to volume constraint. Chapter 4 addresses two basic issues in the thermodynamic optimization of environmental control systems (ECS) for aircraft: realistic limits for the minimal power requirement, and design features that facilitate operation at minimal power consumption. Several models of the ECS-Cabin interaction are considered and it is shown that in all the models the temperature of the air stream that the ECS delivers to the cabin can be optimized for operation at minimal power. In chapter 5 it is shown that the sizes (weights) of heat and fluid flow systems that function on board vehicles such as aircraft can be derived from the maximization of overall (system level) performance. Chapter 6 develops analytically the optimal sizes (hydraulic diameters) of parallel channels that penetrate and cool a volume with uniformly distributed internal heat generation and Chapter 7 shows analytically and numerically how an originally uniform flow structure transforms itself into a nonuniform one when the objective is to minimize global flow losses. It is shown that flow maldistribution and the abandonment of symmetry are necessary for the development of flow structures with minimal resistance. In the second part of the chapter, the flow medium is continuous and permeated by Darcy flow. As flow systems become smaller and more compact, the flow systems themselves become "designed porous media".

Freeform Fluidics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Love, Lonnie J; Richardson, Bradley S; Lind, Randall F

This work explores the integration of miniaturized fluid power and additive manufacturing. Oak Ridge National Laboratory (ORNL) has been developing an approach to miniaturized fluidic actuation and control that enables high dexterity, low cost and a pathway towards energy efficiency. Previous work focused on mesoscale digital control valves (high pressure, low flow) and the integration of actuation and fluid passages directly with the structure. The primary application being fluid powered robotics. The fundamental challenge was part complexity. Additive manufacturing technologies (E-Beam, Laser and Ultrasonic deposition) enable freeform manufacturing using conventional metal alloys with excellent mechanical properties. The combination of thesemore » two technologies (miniaturized fluid power and additive manufacturing) can enable a paradigm shift in fluid power, increasing efficiency while simultaneously reducing weight, size, complexity and cost.« less

Comparison of brachial artery vasoreactivity in elite power athletes and age-matched controls.

PubMed

Welsch, Michael A; Blalock, Paul; Credeur, Daniel P; Parish, Tracie R

2013-01-01

Elite endurance athletes typically have larger arteries contributing to greater skeletal muscle blood flow, oxygen and nutrient delivery and improved physical performance. Few studies have examined structural and functional properties of arteries in power athletes. To compare the size and vasoreactivity of the brachial artery of elite power athletes to age-matched controls. It was hypothesized brachial artery diameters of athletes would be larger, have less vasodilation in response to cuff occlusion, but more constriction after a cold pressor test than age-matched controls. Eight elite power athletes (age = 23 ± 2 years) and ten controls (age = 22 ± 1 yrs) were studied. High-resolution ultrasonography was used to assess brachial artery diameters at rest and following 5 minutes of forearm occlusion (Brachial Artery Flow Mediated Dilation = BAFMD) and a cold pressor test (CPT). Basic fitness measures included a handgrip test and 3-minute step test. Brachial arteries of athletes were larger (Athletes 5.39 ± 1.51 vs. 3.73 ± 0.71 mm, p<0.05), had greater vasodilatory (BAFMD%: Athletes: 8.21 ± 1.78 vs. 5.69 ± 1.56%) and constrictor (CPT %: Athletes: -2.95 ± 1.07 vs. -1.20 ± 0.48%) responses, compared to controls. Vascular operating range (VOR = Peak dilation+Peak Constriction) was also greater in athletes (VOR: Athletes: 0.55 ± 0.15 vs. 0.25 ± 0.18 mm, p<0.05). Athletes had superior handgrip strength (Athletes: 55.92 ± 17.06 vs. 36.77 ± 17.06 kg, p<0.05) but similar heart rate responses at peak (Athletes: 123 ± 16 vs. 130 ± 25 bpm, p>0.05) and 1 minute recovery (Athletes: 88 ± 21 vs. 98 ± 26 bpm, p>0.05) following the step test. Elite power athletes have larger brachial arteries, and greater vasoreactivity (greater vasodilatory and constrictor responses) than age-matched controls, contributing to a significantly greater VOR. These data extend the existence of an 'athlete's artery' as previously shown for elite endurance athletes to elite power athletes, and presents a hypothetical explanation for the functional significance of the 'power athlete's artery'.

Research on Centralized Voltage and Effective Inequality Identification Based on Circuit Analysis Method

NASA Astrophysics Data System (ADS)

Su, Yi; Wang, Feifeng; Lu, Yufeng; Huang, Huimin; Xia, Xiaofei

2017-09-01

This paper is based on affine function equation of the grid and OPF problem, discusses the equivalent of some inequality constraints variables optimizing. Further, we propose the model of injection current and set up the constraint sensitivity index of affine characteristics. The index can be used to identify the central point voltage and effective inequality of the system automatically. And then we can know how to compensate reactive power of the corresponding generator node and control the voltage to ensure the quality of the system voltage. When checking the effective inequalities we introduce cross-solving method of power flow. This provide a different idea for solving the power flow. The paper uses the results of the IEEE5 node examples to illustrate the validity and practicality of the proposed method.

Transitioning of power flow in beam models with bends

NASA Technical Reports Server (NTRS)

Hambric, Stephen A.

1990-01-01

The propagation of power flow through a dynamically loaded beam model with 90 degree bends is investigated using NASTRAN and McPOW. The transitioning of power flow types (axial, torsional, and flexural) is observed throughout the structure. To get accurate calculations of the torsional response of beams using NASTRAN, torsional inertia effects had to be added to the mass matrix calculation section of the program. Also, mass effects were included in the calculation of BAR forces to improve the continuity of power flow between elements. The importance of including all types of power flow in an analysis, rather than only flexural power, is indicated by the example. Trying to interpret power flow results that only consider flexural components in even a moderately complex problem will result in incorrect conclusions concerning the total power flow field.

Parametric and experimental analysis using a power flow approach

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.

1990-01-01

A structural power flow approach for the analysis of structure-borne transmission of vibrations is used to analyze the influence of structural parameters on transmitted power. The parametric analysis is also performed using the Statistical Energy Analysis approach and the results are compared with those obtained using the power flow approach. The advantages of structural power flow analysis are demonstrated by comparing the type of results that are obtained by the two analytical methods. Also, to demonstrate that the power flow results represent a direct physical parameter that can be measured on a typical structure, an experimental study of structural power flow is presented. This experimental study presents results for an L shaped beam for which an available solution was already obtained. Various methods to measure vibrational power flow are compared to study their advantages and disadvantages.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano

Past works that focused on addressing power-quality and reliability concerns related to renewable energy resources (RESs) operating with business-as-usual practices have looked at the design of Volt/VAr and Volt/Watt strategies to regulate real or reactive powers based on local voltage measurements, so that terminal voltages are within acceptable levels. These control strategies have the potential of operating at the same time scale of distribution-system dynamics, and can therefore mitigate disturbances precipitated fast time-varying loads and ambient conditions; however, they do not necessarily guarantee system-level optimality, and stability claims are mainly based on empirical evidences. On a different time scale, centralizedmore » and distributed optimal power flow (OPF) algorithms have been proposed to compute optimal steady-state inverter setpoints, so that power losses and voltage deviations are minimized and economic benefits to end-users providing ancillary services are maximized. However, traditional OPF schemes may offer decision making capabilities that do not match the dynamics of distribution systems. Particularly, during the time required to collect data from all the nodes of the network (e.g., loads), solve the OPF, and subsequently dispatch setpoints, the underlying load, ambient, and network conditions may have already changed; in this case, the DER output powers would be consistently regulated around outdated setpoints, leading to suboptimal system operation and violation of relevant electrical limits. The present work focuses on the synthesis of distributed RES-inverter controllers that leverage the opportunities for fast feedback offered by power-electronics interfaced RESs. The overarching objective is to bridge the temporal gap between long-term system optimization and real-time control, to enable seamless RES integration in large scale with stability and efficiency guarantees, while congruently pursuing system-level optimization objectives. The design of the control framework is based on suitable linear approximations of the AC power-flow equations as well as Lagrangian regularization methods. The proposed controllers enable an update of the power outputs at a time scale that is compatible with the underlying dynamics of loads and ambient conditions, and continuously drive the system operation towards OPF-based solutions.« less

Power System Decomposition for Practical Implementation of Bulk-Grid Voltage Control Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vallem, Mallikarjuna R.; Vyakaranam, Bharat GNVSR; Holzer, Jesse T.

Power system algorithms such as AC optimal power flow and coordinated volt/var control of the bulk power system are computationally intensive and become difficult to solve in operational time frames. The computational time required to run these algorithms increases exponentially as the size of the power system increases. The solution time for multiple subsystems is less than that for solving the entire system simultaneously, and the local nature of the voltage problem lends itself to such decomposition. This paper describes an algorithm that can be used to perform power system decomposition from the point of view of the voltage controlmore » problem. Our approach takes advantage of the dominant localized effect of voltage control and is based on clustering buses according to the electrical distances between them. One of the contributions of the paper is to use multidimensional scaling to compute n-dimensional Euclidean coordinates for each bus based on electrical distance to perform algorithms like K-means clustering. A simple coordinated reactive power control of photovoltaic inverters for voltage regulation is used to demonstrate the effectiveness of the proposed decomposition algorithm and its components. The proposed decomposition method is demonstrated on the IEEE 118-bus system.« less

AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT XXIV, MICHIGAN/CLARK TRANSMISSION--OIL FLOW THROUGH THE CONTROL COVER ASSEMBLY.

ERIC Educational Resources Information Center

Human Engineering Inst., Cleveland, OH.

THIS MODULE OF A 25-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE SERVICING PROCEDURES FOR THE CONTROL SYSTEM OF A SPECIFIC TRANSMISSION USED ON DIESEL POWERED EQUIPMENT. TOPICS ARE EXAMINING THE CONTROL COVER ASSEMBLY, REGULATING VALVE AND SAFETY VALVE, AND INSPECTING THE SYSTEM. THE MODULE CONSISTS OF A SELF-INSTRUCTIONAL…

Integration of plug-in hybrid electric vehicles (PHEV) with grid connected residential photovoltaic energy systems

NASA Astrophysics Data System (ADS)

Nagarajan, Adarsh; Shireen, Wajiha

2013-06-01

This paper proposes an approach for integrating Plug-In Hybrid Electric Vehicles (PHEV) to an existing residential photovoltaic system, to control and optimize the power consumption of residential load. Control involves determining the source from which residential load will be catered, where as optimization of power flow reduces the stress on the grid. The system built to achieve the goal is a combination of the existing residential photovoltaic system, PHEV, Power Conditioning Unit (PCU), and a controller. The PCU involves two DC-DC Boost Converters and an inverter. This paper emphasizes on developing the controller logic and its implementation in order to accommodate the flexibility and benefits of the proposed integrated system. The proposed controller logic has been simulated using MATLAB SIMULINK and further implemented using Digital Signal Processor (DSP) microcontroller, TMS320F28035, from Texas Instruments

An analogue study of the influence of solidification on the advance and surface thermal signature of lava flows

NASA Astrophysics Data System (ADS)

Garel, F.; Kaminski, E.; Tait, S.; Limare, A.

2014-06-01

The prediction of lava flow advance and velocity is crucial during an effusive volcanic crisis. The effusion rate is a key control of lava dynamics, and proxies have been developed to estimate it in near real-time. The thermal proxy in predominant use links the satellite-measured thermal radiated power to the effusion rate. It lacks however a robust physical basis to allow time-dependent modeling. We investigate here through analogue experiments the coupling between the spreading of a solidifying flow and its surface thermal signal. We extract a first order behavior from experimental results obtained using polyethylene glycol (PEG) wax, that solidifies abruptly during cooling. We find that the flow advance is discontinuous, with relatively low supply rates yielding long stagnation phases and compound flows. Flows with higher supply rates are less sensitive to solidification and display a spreading behavior closer to that of purely viscous currents. The total power radiated from the upper surface also grows by stages, but the signal radiated by the hottest and liquid part of the flow reaches a quasi-steady state after some time. This plateau value scales around half of the theoretical prediction of a model developed previously for the spreading and cooling of isoviscous gravity currents. The corrected scaling yields satisfying estimates of the effusion rate from the total radiated power measured on a range of basaltic lava flows. We conclude that a gross estimate of the supply rate of solidifying flows can be retrieved from thermal remote-sensing, but the predictions of lava advance as a function of effusion rate appears a more difficult task due to chaotic emplacement of solidifying flows.

Mesoscopic Length Scale Controls the Rheology of Dense Suspensions

NASA Astrophysics Data System (ADS)

Bonnoit, Claire; Lanuza, Jose; Lindner, Anke; Clement, Eric

2010-09-01

From the flow properties of dense granular suspensions on an inclined plane, we identify a mesoscopic length scale strongly increasing with volume fraction. When the flowing layer height is larger than this length scale, a diverging Newtonian viscosity is determined. However, when the flowing layer height drops below this scale, we evidence a nonlocal effective viscosity, decreasing as a power law of the flow height. We establish a scaling relation between this mesoscopic length scale and the suspension viscosity. These results support recent theoretical and numerical results implying collective and clustered granular motion when the jamming point is approached from below.

Mesoscopic length scale controls the rheology of dense suspensions.

PubMed

Bonnoit, Claire; Lanuza, Jose; Lindner, Anke; Clement, Eric

2010-09-03

From the flow properties of dense granular suspensions on an inclined plane, we identify a mesoscopic length scale strongly increasing with volume fraction. When the flowing layer height is larger than this length scale, a diverging Newtonian viscosity is determined. However, when the flowing layer height drops below this scale, we evidence a nonlocal effective viscosity, decreasing as a power law of the flow height. We establish a scaling relation between this mesoscopic length scale and the suspension viscosity. These results support recent theoretical and numerical results implying collective and clustered granular motion when the jamming point is approached from below.

76 FR 20971 - Free Flow Power Corporation; Notice of Intent To File License Application, Filing of Pre...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-14

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. P-13346-001] Free Flow...: February 18, 2011. d. Submitted By: Free Flow Power Corporation (Free Flow Power), on behalf of its... Officer, Free Flow Power Corporation, 239 Causeway Street, Boston, MA 02114-2130; or at (978) 283-2822. i...

Radiation tolerant power converter controls

NASA Astrophysics Data System (ADS)

Todd, B.; Dinius, A.; King, Q.; Uznanski, S.

2012-11-01

The Large Hadron Collider (LHC) at the European Organisation for Nuclear Research (CERN) is the world's most powerful particle collider. The LHC has several thousand magnets, both warm and super-conducting, which are supplied with current by power converters. Each converter is controlled by a purpose-built electronic module called a Function Generator Controller (FGC). The FGC allows remote control of the power converter and forms the central part of a closed-loop control system where the power converter voltage is set, based on the converter output current and magnet-circuit characteristics. Some power converters and FGCs are located in areas which are exposed to beam-induced radiation. There are numerous radiation induced effects, some of which lead to a loss of control of the power converter, having a direct impact upon the accelerator's availability. Following the first long shut down (LS1), the LHC will be able to run with higher intensity beams and higher beam energy. This is expected to lead to significantly increased radiation induced effects in materials close to the accelerator, including the FGC. Recent radiation tests indicate that the current FGC would not be sufficiently reliable. A so-called FGClite is being designed to work reliably in the radiation environment in the post-LS1 era. This paper outlines the concepts of power converter controls for machines such as the LHC, introduces the risks related to radiation and a radiation tolerant project flow. The FGClite is then described, with its key concepts and challenges: aiming for high reliability in a radiation field.

The impact of circulation control on rotary aircraft controls systems

NASA Technical Reports Server (NTRS)

Kingloff, R. F.; Cooper, D. E.

1987-01-01

Application of circulation to rotary wing systems is a new development. Efforts to determine the near and far field flow patterns and to analytically predict those flow patterns have been underway for some years. Rotary wing applications present a new set of challenges in circulation control technology. Rotary wing sections must accommodate substantial Mach number, free stream dynamic pressure and section angle of attack variation at each flight condition within the design envelope. They must also be capable of short term circulation blowing modulation to produce control moments and vibration alleviation in addition to a lift augmentation function. Control system design must provide this primary control moment, vibration alleviation and lift augmentation function. To accomplish this, one must simultaneously control the compressed air source and its distribution. The control law algorithm must therefore address the compressor as the air source, the plenum as the air pressure storage and the pneumatic flow gates or valves that distribute and meter the stored pressure to the rotating blades. Also, mechanical collective blade pitch, rotor shaft angle of attack and engine power control must be maintained.

Parametric and experimental analysis using a power flow approach

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.

1988-01-01

Having defined and developed a structural power flow approach for the analysis of structure-borne transmission of structural vibrations, the technique is used to perform an analysis of the influence of structural parameters on the transmitted energy. As a base for comparison, the parametric analysis is first performed using a Statistical Energy Analysis approach and the results compared with those obtained using the power flow approach. The advantages of using structural power flow are thus demonstrated by comparing the type of results obtained by the two methods. Additionally, to demonstrate the advantages of using the power flow method and to show that the power flow results represent a direct physical parameter that can be measured on a typical structure, an experimental investigation of structural power flow is also presented. Results are presented for an L-shaped beam for which an analytical solution has already been obtained. Furthermore, the various methods available to measure vibrational power flow are compared to investigate the advantages and disadvantages of each method.

Automatic Learning of Fine Operating Rules for Online Power System Security Control.

PubMed

Sun, Hongbin; Zhao, Feng; Wang, Hao; Wang, Kang; Jiang, Weiyong; Guo, Qinglai; Zhang, Boming; Wehenkel, Louis

2016-08-01

Fine operating rules for security control and an automatic system for their online discovery were developed to adapt to the development of smart grids. The automatic system uses the real-time system state to determine critical flowgates, and then a continuation power flow-based security analysis is used to compute the initial transfer capability of critical flowgates. Next, the system applies the Monte Carlo simulations to expected short-term operating condition changes, feature selection, and a linear least squares fitting of the fine operating rules. The proposed system was validated both on an academic test system and on a provincial power system in China. The results indicated that the derived rules provide accuracy and good interpretability and are suitable for real-time power system security control. The use of high-performance computing systems enables these fine operating rules to be refreshed online every 15 min.

Graphical models for optimal power flow

DOE PAGES

Dvijotham, Krishnamurthy; Chertkov, Michael; Van Hentenryck, Pascal; ...

2016-09-13

Optimal power flow (OPF) is the central optimization problem in electric power grids. Although solved routinely in the course of power grid operations, it is known to be strongly NP-hard in general, and weakly NP-hard over tree networks. In this paper, we formulate the optimal power flow problem over tree networks as an inference problem over a tree-structured graphical model where the nodal variables are low-dimensional vectors. We adapt the standard dynamic programming algorithm for inference over a tree-structured graphical model to the OPF problem. Combining this with an interval discretization of the nodal variables, we develop an approximation algorithmmore » for the OPF problem. Further, we use techniques from constraint programming (CP) to perform interval computations and adaptive bound propagation to obtain practically efficient algorithms. Compared to previous algorithms that solve OPF with optimality guarantees using convex relaxations, our approach is able to work for arbitrary tree-structured distribution networks and handle mixed-integer optimization problems. Further, it can be implemented in a distributed message-passing fashion that is scalable and is suitable for “smart grid” applications like control of distributed energy resources. In conclusion, numerical evaluations on several benchmark networks show that practical OPF problems can be solved effectively using this approach.« less

Singlet delta oxygen production in a 2D micro-discharge array in air: effect of gas residence time and discharge power

NASA Astrophysics Data System (ADS)

Nayak, Gaurav; Santos Sousa, João; Bruggeman, Peter J.

2017-03-01

The production of singlet delta oxygen (O2(a 1Δg)) is of growing interest for many applications. We report on the measurement of O2(a 1Δg) and ozone (O3) in a room temperature atmospheric pressure discharge in dry air. The plasma source is a 2D array of micro-discharges generated by an alternating current voltage at 20 kHz. The study focuses on the effect of gas flow through the discharge. The maximum investigated flow rate allows reducing the gas residence time in the discharge zone to half the discharge period. Results indicate that the residence time and discharge power have a major effect on the O2(a 1Δg) production. Different O2(a 1Δg) density dependencies on power are observed for different flow rates. Effects of collisional quenching on the as-produced and measured O2(a 1Δg) densities are discussed. The flow rate also allows for control of the O2(a 1Δg) to O3 density ratio in the effluent from 0.7 to conditions of pure O3.

Methanol tailgas combustor control method

DOEpatents

Hart-Predmore, David J.; Pettit, William H.

2002-01-01

A method for controlling the power and temperature and fuel source of a combustor in a fuel cell apparatus to supply heat to a fuel processor where the combustor has dual fuel inlet streams including a first fuel stream, and a second fuel stream of anode effluent from the fuel cell and reformate from the fuel processor. In all operating modes, an enthalpy balance is determined by regulating the amount of the first and/or second fuel streams and the quantity of the first air flow stream to support fuel processor power requirements.

Proceedings of the ISTVS (International Society for Terrain-Vehicle Systems) Workshop on Measurement and Evaluation of Tire Performance under Winter Conditions, Alta, Utah, 11-14 April 1983.

DTIC Science & Technology

1985-09-01

Transducers capable of measuring electro-hydraulic control system which fore-aft and vertical load on a driven controls the brake system to deactivate tire...power. * axle allows design of all load-carrying - System logic power. ENGINE I EXTERNAL COMPARTMENT COMPONENTS CAB Brake Levelin system I trans... brake con- The TWS DAS was designed to 1) pro- trol system . vide onboard data sampling and filtering, A simplified truck operational flow chart 2) make

Hybrid Manipulation of Streamwise Vorticity in a Diffuser Boundary Layer

NASA Astrophysics Data System (ADS)

Gissen, Abraham; Vukasinovic, Bojan; Culp, John; Glezer, Ari

2010-11-01

The formation of streamwise vorticity concentrations by exploiting the interaction of surface-mounted passive (micro-vanes) and active (synthetic jets) flow control elements with the cross flow is investigated experimentally in a small-scale serpentine duct at high subsonic speeds (up to M = 0.6). Streamwise vortices can be a key element in the mitigation of the adverse effects on pressure recovery and distortion caused by the naturally occurring secondary flows in embedded propulsion systems with complex inlet geometries. Counter rotating and single-sense vortices are formed using conventional passive micro-vanes and active high-power synthetic jet actuators. Interaction of the flow control elements is examined through a hybrid actuation scheme whereby synthetic jet actuation augments the primary vanes' vortices resulting in dynamic enhancement of their strength. It is shown that such sub-boundary layer individual vortices can merge and evolve into duct-scale vortical structures that counteract the inherent secondary flow and mitigates global flow distortion.

Fuel cell system modeling for solid oxide fuel cell/gas turbine hybrid power plants, Part I: Modeling and simulation framework

NASA Astrophysics Data System (ADS)

Leucht, Florian; Bessler, Wolfgang G.; Kallo, Josef; Friedrich, K. Andreas; Müller-Steinhagen, H.

A sustainable future power supply requires high fuel-to-electricity conversion efficiencies even in small-scale power plants. A promising technology to reach this goal is a hybrid power plant in which a gas turbine (GT) is coupled with a solid oxide fuel cell (SOFC). This paper presents a dynamic model of a pressurized SOFC system consisting of the fuel cell stack with combustion zone and balance-of-plant components such as desulphurization, humidification, reformer, ejector and heat exchangers. The model includes thermal coupling between the different components. A number of control loops for fuel and air flows as well as power management are integrated in order to keep the system within the desired operation window. Models and controls are implemented in a MATLAB/SIMULINK environment. Different hybrid cycles proposed earlier are discussed and a preferred cycle is developed. Simulation results show the prospects of the developed modeling and control system.

Local Voltage Control in Distribution Networks: A Game-Theoretic Perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xinyang; Tian, Jie; Chen, Lijun

Inverter-based voltage regulation is gaining importance to alleviate emerging reliability and power-quality concerns related to distribution systems with high penetration of photovoltaic (PV) systems. This paper seeks contribution in the domain of reactive power compensation by establishing stability of local Volt/VAr controllers. In lieu of the approximate linear surrogate used in the existing work, the paper establishes existence and uniqueness of an equilibrium point using nonlinear AC power flow model. Key to this end is to consider a nonlinear dynamical system with non-incremental local Volt/VAr control, cast the Volt/VAr dynamics as a game, and leverage the fixed-point theorem as wellmore » as pertinent contraction mapping argument. Numerical examples are provided to complement the analytical results.« less

Local Voltage Control in Distribution Networks: A Game-Theoretic Perspective: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Xinyang; Tian, Jie; Chen, Lijun

Inverter-based voltage regulation is gaining importance to alleviate emerging reliability and power-quality concerns related to distribution systems with high penetration of photovoltaic (PV) systems. This paper seeks contribution in the domain of reactive power compensation by establishing stability of local Volt/VAr controllers. In lieu of the approximate linear surrogate used in the existing work, the paper establishes existence and uniqueness of an equilibrium point using nonlinear AC power flow model. Key to this end is to consider a nonlinear dynamical system with non-incremental local Volt/VAr control, cast the Volt/VAr dynamics as a game, and leverage the fixed-point theorem as wellmore » as pertinent contraction mapping argument. Numerical examples are provided to complement the analytical results.« less

Convection- and SASI-driven flows in parametrized models of core-collapse supernova explosions

DOE PAGES

Endeve, E.; Cardall, C. Y.; Budiardja, R. D.; ...

2016-01-21

We present initial results from three-dimensional simulations of parametrized core-collapse supernova (CCSN) explosions obtained with our astrophysical simulation code General Astrophysical Simulation System (GenASIS). We are interested in nonlinear flows resulting from neutrino-driven convection and the standing accretion shock instability (SASI) in the CCSN environment prior to and during the explosion. By varying parameters in our model that control neutrino heating and shock dissociation, our simulations result in convection-dominated and SASI-dominated evolution. We describe this initial set of simulation results in some detail. To characterize the turbulent flows in the simulations, we compute and compare velocity power spectra from convection-dominatedmore » and SASI-dominated (both non-exploding and exploding) models. When compared to SASI-dominated models, convection-dominated models exhibit significantly more power on small spatial scales.« less

77 FR 3761 - Free Flow Power Corporation, Northland Power Mississippi River LLC; Notice Announcing Filing...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-01-25

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 12817-002, Project No. 14083-000] Free Flow Power Corporation, Northland Power Mississippi River LLC; Notice Announcing Filing... priority is as follows: 1. Free Flow Power Corporation; Project No. 12817-002. 2. Northland Power...

A predication model for combustion modes of the scramjet-powered aerospace vehicle based on the nonlinear features of the isolator flow field

NASA Astrophysics Data System (ADS)

Yang, Qingchun; Wang, Hongxin; Chetehouna, Khaled; Gascoin, Nicolas

2017-01-01

The supersonic combustion ramjet (scramjet) engine remains the most promising airbreathing engine cycle for hypersonic flight, particularly the high-performance dual-mode scramjet in the range of flight Mach number from 4 to 7, because it can operates under different combustion modes. Isolator is a very key component of the dual-mode scramjet engine. In this paper, nonlinear characteristics of combustion mode transition is theoretically analyzed. The discontinuous sudden changes of static pressure and Mach number are obtained as the mode transition occurs, which emphasizing the importance of predication and control of combustion modes. In this paper, a predication model of different combustion modes is developed based on these these nonlinear features in the isolator flow field. it can provide a valuable reference for control system design of the scramjet-powered aerospace vehicle.

Active Flow Control: Instrumentation Automation and Experimental Technique

NASA Technical Reports Server (NTRS)

Gimbert, N. Wes

1995-01-01

In investigating the potential of a new actuator for use in an active flow control system, several objectives had to be accomplished, the largest of which was the experimental setup. The work was conducted at the NASA Langley 20x28 Shear Flow Control Tunnel. The actuator named Thunder, is a high deflection piezo device recently developed at Langley Research Center. This research involved setting up the instrumentation, the lighting, the smoke, and the recording devices. The instrumentation was automated by means of a Power Macintosh running LabVIEW, a graphical instrumentation package developed by National Instruments. Routines were written to allow the tunnel conditions to be determined at a given instant at the push of a button. This included determination of tunnel pressures, speed, density, temperature, and viscosity. Other aspects of the experimental equipment included the set up of a CCD video camera with a video frame grabber, monitor, and VCR to capture the motion. A strobe light was used to highlight the smoke that was used to visualize the flow. Additional effort was put into creating a scale drawing of another tunnel on site and a limited literature search in the area of active flow control.

Liquid Bismuth Propellant Management System for the Very High Specific Impulse Thruster with Anode Layer

NASA Technical Reports Server (NTRS)

Polzin, K. A.; Markusic, T. E.; Stanojev, B. J.

2007-01-01

Two prototype bismuth propellant feed systems were constructed and operated in conjunction with a propellant vaporizer. One system provided bismuth to a vaporizer using gas pressurization but did not include a means to measure the flow rate. The second system incorporated an electromagnetic pump to provide fine control of the hydrostatic pressure and a new type of in-line flow sensor that was developed for accurate, real-time measurement of the mass flow rate. High-temperature material compatibility was a driving design requirement for the pump and flow sensor, leading to the selection of Macor for the main body of both components. Posttest inspections of both components revealed no degradation of the material. The gas pressurization system demonstrated continuous pressure control over a range from zero to 200 torr. In separate proof-of-concept experiments, the electromagnetic pump produced a linear pressure rise as a function of current that compared favorably with theoretical pump pressure predictions, producing a pressure rise of 10 kPa at 30 A. Preliminary flow sensor operation indicated a bismuth flow rate of 6 mg/s with an uncertainty of plus or minus 6%. An electronics suite containing a real-time controller was successfully used to control the entire system, simultaneously monitoring all power supplies and performing data acquisition duties.

A network architecture for International Business Satellite communications

NASA Astrophysics Data System (ADS)

Takahata, Fumio; Nohara, Mitsuo; Takeuchi, Yoshio

Demand Assignment (DA) control is expected to be introduced in the International Business Satellte communications (IBS) network in order to cope with a growing international business traffic. The paper discusses the DA/IBS network from the viewpoints of network configuration, satellite channel configuration and DA control. The network configuration proposed here consists of one Central Station with network management function and several Network Coordination Stations with user management function. A satellite channel configuration is also presented along with a tradeoff study on transmission bit rate, high power amplifier output power requirement, and service quality. The DA control flow and protocol based on CCITT Signalling System No. 7 are also proposed.

Evidence of sublaminar drag naturally occurring in a curved pipe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noorani, A.; Schlatter, P., E-mail: pschlatt@mech.kth.se

Steady and unsteady flows in a mildly curved pipe for a wide range of Reynolds numbers are examined with direct numerical simulation. It is shown that in a range of Reynolds numbers in the vicinity of Re{sub b} ≈ 3400, based on bulk velocity and pipe diameter, a marginally turbulent flow is established in which the friction drag naturally reduces below the laminar solution at the same Reynolds number. The obtained values for friction drag for the laminar and turbulent (sublaminar) flows turn out to be in excellent agreement with experimental measurements in the literature. Our results are also inmore » agreement with Fukagata et al. [“On the lower bound of net driving power in controlled duct flows,” Phys. D 238, 1082 (2009)], as the lower bound of net power required to drive the flow, i.e., the pressure drop of the Stokes solution, is still lower than our marginally turbulent flow. A large-scale traveling structure that is thought to be responsible for that behaviour is identified in the instantaneous field. This mode could also be extracted using proper orthogonal decomposition. The effect of this mode is to redistribute the mean flow in the circular cross section which leads to lower gradients at the wall compared to the laminar flow.« less

Evidence of sublaminar drag naturally occurring in a curved pipe

NASA Astrophysics Data System (ADS)

Noorani, A.; Schlatter, P.

2015-03-01

Steady and unsteady flows in a mildly curved pipe for a wide range of Reynolds numbers are examined with direct numerical simulation. It is shown that in a range of Reynolds numbers in the vicinity of Reb ≈ 3400, based on bulk velocity and pipe diameter, a marginally turbulent flow is established in which the friction drag naturally reduces below the laminar solution at the same Reynolds number. The obtained values for friction drag for the laminar and turbulent (sublaminar) flows turn out to be in excellent agreement with experimental measurements in the literature. Our results are also in agreement with Fukagata et al. ["On the lower bound of net driving power in controlled duct flows," Phys. D 238, 1082 (2009)], as the lower bound of net power required to drive the flow, i.e., the pressure drop of the Stokes solution, is still lower than our marginally turbulent flow. A large-scale traveling structure that is thought to be responsible for that behaviour is identified in the instantaneous field. This mode could also be extracted using proper orthogonal decomposition. The effect of this mode is to redistribute the mean flow in the circular cross section which leads to lower gradients at the wall compared to the laminar flow.

An engine trade study for a supersonic STOVL fighter-attack aircraft, volume 1

NASA Technical Reports Server (NTRS)

Beard, B. B.; Foley, W. H.

1982-01-01

The best main engine for an advanced STOVL aircraft flight demonstrator was studied. The STOVL aircraft uses ejectors powered by engine bypass flow together with vectored core exhaust to achieve vertical thrust capability. Bypass flow and core flow are exhausted through separate nozzles during wingborne flight. Six near term turbofan engines were examined for suitability for this aircraft concept. Fan pressure ratio, thrust split between bypass and core flow, and total thrust level were used to compare engines. One of the six candidate engines was selected for the flight demonstrator configuration. Propulsion related to this aircraft concept was studied. A preliminary candidate for the aircraft reaction control system for hover attitude control was selected. A mathematical model of transfer of bypass thrust from ejectors to aft directed nozzle during the transition to wingborne flight was developed. An equation to predict ejector secondary air flow rate and ram drag is derived. Additional topics discussed include: nozzle area control, ejector to engine inlet reingestion, bypass/core thrust split variation, and gyroscopic behavior during hover.

An Investigation of Chaotic Kolmogorov Flows

DTIC Science & Technology

1990-08-01

plane for the Poincare sections used later. The choice of the constant D controls apparent positioning of the hyperplane in the phase...discovered in large scale structure regime. Features of the diverse cases are displayed in terms of the temporal power spectrum, Poincare sections and...examine in some detail the behavior of the flow and its transition states for a range of the bifurcation parameter Re. We use Poincare sections to

Optimal Regulation of Virtual Power Plants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall Anese, Emiliano; Guggilam, Swaroop S.; Simonetto, Andrea

This paper develops a real-time algorithmic framework for aggregations of distributed energy resources (DERs) in distribution networks to provide regulation services in response to transmission-level requests. Leveraging online primal-dual-type methods for time-varying optimization problems and suitable linearizations of the nonlinear AC power-flow equations, we believe this work establishes the system-theoretic foundation to realize the vision of distribution-level virtual power plants. The optimization framework controls the output powers of dispatchable DERs such that, in aggregate, they respond to automatic-generation-control and/or regulation-services commands. This is achieved while concurrently regulating voltages within the feeder and maximizing customers' and utility's performance objectives. Convergence andmore » tracking capabilities are analytically established under suitable modeling assumptions. Simulations are provided to validate the proposed approach.« less

Solar Energy Grid Integration Systems (SEGIS): adding functionality while maintaining reliability and economics

NASA Astrophysics Data System (ADS)

Bower, Ward

2011-09-01

An overview of the activities and progress made during the US DOE Solar Energy Grid Integration Systems (SEGIS) solicitation, while maintaining reliability and economics is provided. The SEGIS R&D opened pathways for interconnecting PV systems to intelligent utility grids and micro-grids of the future. In addition to new capabilities are "value added" features. The new hardware designs resulted in smaller, less material-intensive products that are being viewed by utilities as enabling dispatchable generation and not just unpredictable negative loads. The technical solutions enable "advanced integrated system" concepts and "smart grid" processes to move forward in a faster and focused manner. The advanced integrated inverters/controllers can now incorporate energy management functionality, intelligent electrical grid support features and a multiplicity of communication technologies. Portals for energy flow and two-way communications have been implemented. SEGIS hardware was developed for the utility grid of today, which was designed for one-way power flow, for intermediate grid scenarios, AND for the grid of tomorrow, which will seamlessly accommodate managed two-way power flows as required by large-scale deployment of solar and other distributed generation. The SEGIS hardware and control developed for today meets existing standards and codes AND provides for future connections to a "smart grid" mode that enables utility control and optimized performance.

Supply and Demand Control of Distributed Generators in a Microgrid for New Energy

NASA Astrophysics Data System (ADS)

Shimakage, Toyonari; Sumita, Jiro; Uchiyama, Noriyuki; Kato, Takeyoshi; Suzuoki, Yasuo

We report the operational results of distributed generators (DGs) in a microgrid and present the effects after incorporating photovoltaic power generation (PV) systems into the microgrid for electric power system. The microgrid was constructed at the EXPO 2005 Aichi site as part of a demonstration promoted by NEDO. A solution is needed to problems where instability in the DGs that utilize natural energy such as solar light and wind force negatively influence existing electric power systems. So, we developed energy control system and controlled DGs output to reduce the fluctuation at the grid connected point caused by PV system's instability output. Our microgrid consists of DGs such as PV systems, fuel cells, and NaS batteries, and these DGs are controlled by an energy control system. We verified practical effectiveness of the installing the microgrid as follows. (1) 99.5% of the power imbalance in the supply and demand over 30 minutes was within a range of ±3% under normal operating conditions, (2) the microgrid contributes to the load leveling, (3) energy control system smoothes the power flow fluctuation of PV system output at the grid connected point, (4) in the future, installing a microgrid will help reduce the additional LFC (Load Frequency Control) capacity.

Reduced-Noise Gas Flow Design Guide Developed as a Noise-Control Design Tool for Meeting Glenn's Hearing Conservation and Community Noise Goals

NASA Technical Reports Server (NTRS)

Cooper, Beth A.

2000-01-01

A Reduced-Noise Gas Flow Design Guide has been developed for the NASA Glenn Research Center at Lewis Field by Nelson Acoustical Engineering of Elgin, Texas. Gas flow systems are a significant contributor to t he noise exposure landscape at Glenn. Because of the power of many of these systems, hearing conservation and community noise are importan t issues. The purpose of the Guide is to allow Glenn engineers and de signers to address noise emission and control at the design stage by using readily available system parameters. Although the Guide was deve loped with Glenn equipment and systems in mind, it is expected to hav e wide application in industry.

Technology of forced flow and once-through boiling: A survey. [pressure distribution

NASA Technical Reports Server (NTRS)

Poppendieck, H. F.; Sabin, C. M.

1975-01-01

Representative boiling heat transfer and pressure drop information obtained primarily from past NASA and AEC programs is presented which is applicable to forced flow and once-through boiler systems. The forced convection boiler has a number of advantages: little possibility of flow mal-distribution; heat transfer characteristics are usually consistent; and conductances are predictable, so that higher heat fluxes may be employed with safety (which leads to more compact, lighter weight equipment). It was found that in gas-fired systems particularly, the controlling heat transfer resistance may be on the hot side, so that increased fluxes would require extended surfaces. If in a power generation system the working fluid is very expensive, a forced flow boiler can be designed especially for small holdup volume. If the fluid is temperature sensitive, the boiling side wall temperatures can be tailored to maintain maximum heat transfer rates without overheating the fluid. The forced flow and once-through configurations may be the only type which can satisfy a specific need (such as the automotive Rankine cycle power plant design having a very short time-response boiler).

Characteristics and performance of the variable polarity plasma arc welding process used in the Space Shuttle external tank

NASA Technical Reports Server (NTRS)

Hung, R. J.; Lee, C. C.; Liu, J. W.

1990-01-01

Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. Flow profiles and power distribution of argon plasma gas as a working fluid to produce plasma arc jet in the VPPA welding process was analyzed. Major loss of heat transfer for flow through the nozzle is convective heat transfer; for the plasma jet flow between the outlet of the nozzle and workpiece is radiative heat transfer; and for the flow through the keyhole of the workpiece is convective heat transfer. The majority of the power absorbed by the keyhole of the workpiece is used for melting the solid metal workpiece into a molten metallic puddle. The crown and root widths and the crown and root heights can be predicted. An algorithm for promoting automatic control of flow parameters and the dimensions of the final product of the welding specification to be used for the VPPA Welding System operated at MSFC are provided.

Using artificial intelligence to control fluid flow computations

NASA Technical Reports Server (NTRS)

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.

Active control of panel vibrations induced by a boundary layer flow

NASA Technical Reports Server (NTRS)

Chow, Pao-Liu

1995-01-01

The problems of active and passive control of sound and vibration has been investigated by many researchers for a number of years. However, few of the articles are concerned with the sound and vibration with flow-structure interaction. Experimental and numerical studies on the coupling between panel vibration and acoustic radiation due to flow excitation have been done by Maestrello and his associates at NASA/Langley Research Center. Since the coupled system of nonlinear partial differential equations is formidable, an analytical solution to the full problem seems impossible. For this reason, we have to simplify the problem to that of the nonlinear panel vibration induced by a uniform flow or a boundary-layer flow with a given wall pressure distribution. Based on this simplified model, we have been able to consider the control and stabilization of the nonlinear panel vibration, which have not been treated satisfactorily by other authors. Although the sound radiation has not been included, the vibration suppression will clearly reduce the sound radiation power from the panel. The major research findings are presented in three sections. In section two we describe results on the boundary control of nonlinear panel vibration, with or without flow excitation. Sections three and four are concerned with some analytical and numerical results in the optimal control of the linear and nonlinear panel vibrations, respectively, excited by the flow pressure fluctuations. Finally, in section five, we draw some conclusions from research findings.

78 FR 33400 - Free Flow Power Corporation; Notice Soliciting Scoping Comments

Federal Register 2010, 2011, 2012, 2013, 2014

2013-06-04

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [ Project No. 13346-003] Free Flow Power... Major License. b. Project No.: P-13346-003. c. Date filed: December 3, 2012. d. Applicant: Free Flow Power Corporation (Free Flow Power), on behalf of its subsidiary PayneBridge, LLC. e. Name of Project...

Wind Farm Flow Modeling using an Input-Output Reduced-Order Model

DOE Office of Scientific and Technical Information (OSTI.GOV)

Annoni, Jennifer; Gebraad, Pieter; Seiler, Peter

Wind turbines in a wind farm operate individually to maximize their own power regardless of the impact of aerodynamic interactions on neighboring turbines. There is the potential to increase power and reduce overall structural loads by properly coordinating turbines. To perform control design and analysis, a model needs to be of low computational cost, but retains the necessary dynamics seen in high-fidelity models. The objective of this work is to obtain a reduced-order model that represents the full-order flow computed using a high-fidelity model. A variety of methods, including proper orthogonal decomposition and dynamic mode decomposition, can be used tomore » extract the dominant flow structures and obtain a reduced-order model. In this paper, we combine proper orthogonal decomposition with a system identification technique to produce an input-output reduced-order model. This technique is used to construct a reduced-order model of the flow within a two-turbine array computed using a large-eddy simulation.« less

Wave propagation and power flow in an acoustic metamaterial plate with lateral local resonance attachment

NASA Astrophysics Data System (ADS)

Wang, Ting; Sheng, Meiping; Ding, Xiaodong; Yan, Xiaowei

2018-03-01

This paper presents analysis on wave propagation and power flow in an acoustic metamaterial plate with lateral local resonance. The metamaterial is designed to have lateral local resonance systems attached to a homogeneous plate. Relevant theoretical analysis, numerical modelling and application prospect are presented. Results show that the metamaterial has two complete band gaps for flexural wave absorption and vibration attenuation. Damping can smooth and lower the metamaterial’s frequency responses in high frequency ranges at the expense of the band gap effect, and as an important factor to calculate the power flow is thoroughly investigated. Moreover, the effective mass density becomes negative and unbounded at specific frequencies. Simultaneously, power flow within band gaps are dramatically blocked from the power flow contour and power flow maps. Results from finite element modelling and power flow analysis reveal the working mechanism of the flexural wave attenuation and power flow blocked within the band gaps, where part of the flexural vibration is absorbed by the vertical resonator and the rest is transformed through four-link-mechanisms to the lateral resonators that oscillate and generate inertial forces indirectly to counterbalance the shear forces induced by the vibrational plate. The power flow is stored in the vertical and lateral local resonance, as well as in the connected plate.

Power flow analysis of two coupled plates with arbitrary characteristics

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.

1990-01-01

In the last progress report (Feb. 1988) some results were presented for a parametric analysis on the vibrational power flow between two coupled plate structures using the mobility power flow approach. The results reported then were for changes in the structural parameters of the two plates, but with the two plates identical in their structural characteristics. Herein, limitation is removed. The vibrational power input and output are evaluated for different values of the structural damping loss factor for the source and receiver plates. In performing this parametric analysis, the source plate characteristics are kept constant. The purpose of this parametric analysis is to determine the most critical parameters that influence the flow of vibrational power from the source plate to the receiver plate. In the case of the structural damping parametric analysis, the influence of changes in the source plate damping is also investigated. The results obtained from the mobility power flow approach are compared to results obtained using a statistical energy analysis (SEA) approach. The significance of the power flow results are discussed together with a discussion and a comparison between the SEA results and the mobility power flow results. Furthermore, the benefits derived from using the mobility power flow approach are examined.

Bidirectional control system for energy flow in solar powered flywheel

NASA Technical Reports Server (NTRS)

Nola, Frank J. (Inventor)

1987-01-01

An energy storage system for a spacecraft is provided which employs a solar powered flywheel arrangement including a motor/generator which, in different operating modes, drives the flywheel and is driven thereby. A control circuit, including a threshold comparator, senses the output of a solar energy converter, and when a threshold voltage is exceeded thereby indicating the availability of solar power for the spacecraft loads, activates a speed control loop including the motor/generator so as to accelerate the flywheel to a constant speed and thereby store mechanical energy, while also supplying energy from the solar converter to the loads. Under circumstances where solar energy is not available and thus the threshold voltage is not exceeded, the control circuit deactivates the speed control loop and activates a voltage control loop that provides for operation of the motor as a generator so that mechanical energy from the flywheel is converted into electrical energy for supply to the spacecraft loads.

Advanced Distribution Network Modelling with Distributed Energy Resources

NASA Astrophysics Data System (ADS)

O'Connell, Alison

The addition of new distributed energy resources, such as electric vehicles, photovoltaics, and storage, to low voltage distribution networks means that these networks will undergo major changes in the future. Traditionally, distribution systems would have been a passive part of the wider power system, delivering electricity to the customer and not needing much control or management. However, the introduction of these new technologies may cause unforeseen issues for distribution networks, due to the fact that they were not considered when the networks were originally designed. This thesis examines different types of technologies that may begin to emerge on distribution systems, as well as the resulting challenges that they may impose. Three-phase models of distribution networks are developed and subsequently utilised as test cases. Various management strategies are devised for the purposes of controlling distributed resources from a distribution network perspective. The aim of the management strategies is to mitigate those issues that distributed resources may cause, while also keeping customers' preferences in mind. A rolling optimisation formulation is proposed as an operational tool which can manage distributed resources, while also accounting for the uncertainties that these resources may present. Network sensitivities for a particular feeder are extracted from a three-phase load flow methodology and incorporated into an optimisation. Electric vehicles are the focus of the work, although the method could be applied to other types of resources. The aim is to minimise the cost of electric vehicle charging over a 24-hour time horizon by controlling the charge rates and timings of the vehicles. The results demonstrate the advantage that controlled EV charging can have over an uncontrolled case, as well as the benefits provided by the rolling formulation and updated inputs in terms of cost and energy delivered to customers. Building upon the rolling optimisation, a three-phase optimal power flow method is developed. The formulation has the capability to provide optimal solutions for distribution system control variables, for a chosen objective function, subject to required constraints. It can, therefore, be utilised for numerous technologies and applications. The three-phase optimal power flow is employed to manage various distributed resources, such as photovoltaics and storage, as well as distribution equipment, including tap changers and switches. The flexibility of the methodology allows it to be applied in both an operational and a planning capacity. The three-phase optimal power flow is employed in an operational planning capacity to determine volt-var curves for distributed photovoltaic inverters. The formulation finds optimal reactive power settings for a number of load and solar scenarios and uses these reactive power points to create volt-var curves. Volt-var curves are determined for 10 PV systems on a test feeder. A universal curve is also determined which is applicable to all inverters. The curves are validated by testing them in a power flow setting over a 24-hour test period. The curves are shown to provide advantages to the feeder in terms of reduction of voltage deviations and unbalance, with the individual curves proving to be more effective. It is also shown that adding a new PV system to the feeder only requires analysis for that system. In order to represent the uncertainties that inherently occur on distribution systems, an information gap decision theory method is also proposed and integrated into the three-phase optimal power flow formulation. This allows for robust network decisions to be made using only an initial prediction for what the uncertain parameter will be. The work determines tap and switch settings for a test network with demand being treated as uncertain. The aim is to keep losses below a predefined acceptable value. The results provide the decision maker with the maximum possible variation in demand for a given acceptable variation in the losses. A validation is performed with the resulting tap and switch settings being implemented, and shows that the control decisions provided by the formulation keep losses below the acceptable value while adhering to the limits imposed by the network.

Reactive power compensator

DOEpatents

El-Sharkawi, Mohamed A.; Venkata, Subrahmanyam S.; Chen, Mingliang; Andexler, George; Huang, Tony

1992-01-01

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation.

Reactive Power Compensator.

DOEpatents

El-Sharkawi, M.A.; Venkata, S.S.; Chen, M.; Andexler, G.; Huang, T.

1992-07-28

A system and method for determining and providing reactive power compensation for an inductive load. A reactive power compensator (50,50') monitors the voltage and current flowing through each of three distribution lines (52a, 52b, 52c), which are supplying three-phase power to one or more inductive loads. Using signals indicative of the current on each of these lines when the voltage waveform on the line crosses zero, the reactive power compensator determines a reactive power compensator capacitance that must be connected to the lines to maintain a desired VAR level, power factor, or line voltage. Alternatively, an operator can manually select a specific capacitance for connection to each line, or the capacitance can be selected based on a time schedule. The reactive power compensator produces control signals, which are coupled through optical fibers (102/106) to a switch driver (110, 110') to select specific compensation capacitors (112) for connections to each line. The switch driver develops triggering signals that are supplied to a plurality of series-connected solid state switches (350), which control charge current in one direction in respect to ground for each compensation capacitor. During each cycle, current flows from ground to charge the capacitors as the voltage on the line begins to go negative from its positive peak value. The triggering signals are applied to gate the solid state switches into a conducting state when the potential on the lines and on the capacitors reaches a negative peak value, thereby minimizing both the potential difference and across the charge current through the switches when they begin to conduct. Any harmonic distortion on the potential and current carried by the lines is filtered out from the current and potential signals used by the reactive power compensator so that it does not affect the determination of the required reactive compensation. 26 figs.

Fluid Distribution for In-space Cryogenic Propulsion

NASA Technical Reports Server (NTRS)

Lear, William

2005-01-01

The ultimate goal of this task is to enable the use of a single supply of cryogenic propellants for three distinct spacecraft propulsion missions: main propulsion, orbital maneuvering, and attitude control. A fluid distribution system is sought which allows large propellant flows during the first two missions while still allowing control of small propellant flows during attitude control. Existing research has identified the probable benefits of a combined thermal management/power/fluid distribution system based on the Solar Integrated Thermal Management and Power (SITMAP) cycle. Both a numerical model and an experimental model are constructed in order to predict the performance of such an integrated thermal management/propulsion system. This research task provides a numerical model and an experimental apparatus which will simulate an integrated thermal/power/fluid management system based on the SITMAP cycle, and assess its feasibility for various space missions. Various modifications are done to the cycle, such as the addition of a regeneration process that allows heat to be transferred into the working fluid prior to the solar collector, thereby reducing the collector size and weight. Fabri choking analysis was also accounted for. Finally the cycle is to be optimized for various space missions based on a mass based figure of merit, namely the System Mass Ratio (SMR). -. 1 he theoretical and experimental results from these models are be used to develop a design code (JETSIT code) which is able to provide design parameters for such a system, over a range of cooling loads, power generation, and attitude control thrust levels. The performance gains and mass savings will be compared to those of existing spacecraft systems.

Wave Intensity Analysis Provides Novel Insights Into Pulmonary Arterial Hypertension and Chronic Thromboembolic Pulmonary Hypertension.

PubMed

Su, Junjing; Manisty, Charlotte; Parker, Kim H; Simonsen, Ulf; Nielsen-Kudsk, Jens Erik; Mellemkjaer, Soren; Connolly, Susan; Lim, P Boon; Whinnett, Zachary I; Malik, Iqbal S; Watson, Geoffrey; Davies, Justin E; Gibbs, Simon; Hughes, Alun D; Howard, Luke

2017-10-31

In contrast to systemic hypertension, the significance of arterial waves in pulmonary hypertension (PH) is not well understood. We hypothesized that arterial wave energy and wave reflection are augmented in PH and that wave behavior differs between patients with pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). Right heart catheterization was performed using a pressure and Doppler flow sensor-tipped catheter to obtain simultaneous pressure and flow velocity measurements in the pulmonary artery. Wave intensity analysis was subsequently applied to the acquired data. Ten control participants, 11 patients with PAH, and 10 patients with CTEPH were studied. Wave speed and wave power were significantly greater in PH patients compared with controls, indicating increased arterial stiffness and right ventricular work, respectively. The ratio of wave power to mean right ventricular power was lower in PAH patients than CTEPH patients and controls. Wave reflection index in PH patients (PAH: ≈25%; CTEPH: ≈30%) was significantly greater compared with controls (≈4%), indicating downstream vascular impedance mismatch. Although wave speed was significantly correlated to disease severity, wave reflection indexes of patients with mildly and severely elevated pulmonary pressures were similar. Wave reflection in the pulmonary artery increased in PH and was unrelated to severity, suggesting that vascular impedance mismatch occurs early in the development of pulmonary vascular disease. The lower wave power fraction in PAH compared with CTEPH indicates differences in the intrinsic and/or extrinsic ventricular load between the 2 diseases. © 2017 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley.

Droop Control of Solar PV, Grid and Critical Load using Suppressing DC Current Injection Technique without Battery Storage

NASA Astrophysics Data System (ADS)

Dama Mr., Jayachandra; (Mrs. , Lini Mathew, Dr.; Srikanth Mr., G.

2017-08-01

This paper presents design of a sustainable solar Photo voltaic system for an Indian cities based residential/community house, integrated with grid, supporting it as supplementary sources, to meet energy demand of domestic loads. The role of renewable energy sources in Distributed Generation (DG) is increasingly being recognized as a supplement and an alternative to large conventional central power supply. Though centralized economic system that solely depends on cities is hampered due to energy deficiency, the use of solar energy in cities is never been tried widely due to technical inconvenience and high installation cost. To mitigate these problems, this paper proposes an optimized design of grid-tied PV system without storage which is suitable for Indian origin as it requires less installallation cost and supplies residential loads when the grid power is unavailable. The energy requirement is mainly fulfilled from PV energy module for critical load of a city located residential house and supplemented by grid/DG for base and peak load. The system has been developed for maximum daily household demand of 50kWp and can be scaled to any higher value as per requirement of individual/community building ranging from 50kWp to 60kWp as per the requirement. A simplified control system model has been developed to optimize and control flow of power from these sources. The simulation work, using MATLAB Simulink software for proposed energy management, has resulted in an optimal yield leading efficient power flow control of proposed system.

AUTOMOTIVE DIESEL MAINTENANCE 2. UNIT XXIII, MICHIGAN/CLARK TRANSMISSION--HYDRAULIC SHIFT.

ERIC Educational Resources Information Center

Minnesota State Dept. of Education, St. Paul. Div. of Vocational and Technical Education.

THIS MODULE OF A 25-MODULE COURSE IS DESIGNED TO DEVELOP AN UNDERSTANDING OF THE SHIFTING AND CONTROL FUNCTIONS OF A SPECIFIC TRANSMISSION USED ON DIESEL POWERED EQUIPMENT. TOPICS ARE MECHANICAL AND HYDRAULIC SHIFTING, AND OIL FLOW THROUGH THE CONTROL VALVE. THE MODULE CONSISTS OF A SELF-INSTRUCTIONAL PROGRAMED TRAINING FILM "MICHIGAN/CLARK…

A pattern-based analysis of clinical computer-interpretable guideline modeling languages.

PubMed

Mulyar, Nataliya; van der Aalst, Wil M P; Peleg, Mor

2007-01-01

Languages used to specify computer-interpretable guidelines (CIGs) differ in their approaches to addressing particular modeling challenges. The main goals of this article are: (1) to examine the expressive power of CIG modeling languages, and (2) to define the differences, from the control-flow perspective, between process languages in workflow management systems and modeling languages used to design clinical guidelines. The pattern-based analysis was applied to guideline modeling languages Asbru, EON, GLIF, and PROforma. We focused on control-flow and left other perspectives out of consideration. We evaluated the selected CIG modeling languages and identified their degree of support of 43 control-flow patterns. We used a set of explicitly defined evaluation criteria to determine whether each pattern is supported directly, indirectly, or not at all. PROforma offers direct support for 22 of 43 patterns, Asbru 20, GLIF 17, and EON 11. All four directly support basic control-flow patterns, cancellation patterns, and some advance branching and synchronization patterns. None support multiple instances patterns. They offer varying levels of support for synchronizing merge patterns and state-based patterns. Some support a few scenarios not covered by the 43 control-flow patterns. CIG modeling languages are remarkably close to traditional workflow languages from the control-flow perspective, but cover many fewer workflow patterns. CIG languages offer some flexibility that supports modeling of complex decisions and provide ways for modeling some decisions not covered by workflow management systems. Workflow management systems may be suitable for clinical guideline applications.

The efficacy of stream power and flow duration on geomorphic responses to catastrophic flooding

NASA Astrophysics Data System (ADS)

Magilligan, F. J.; Buraas, E. M.; Renshaw, C. E.

2015-01-01

Geomorphologists have long studied the impacts of extreme floods, yet the association between the magnitude of flow parameters (discharge, velocity, shear stress, or stream power) and resulting geomorphic effectiveness remains vague and non-deterministic. Attempts have been made to include flow duration and total expenditure of stream power, in combination with peak unit stream power, as important variables, but there has been minimal exploration of this hydraulic combination. Taking advantage of Tropical Storm Irene's rapid track through eastern Vermont (USA) in late summer 2011, this paper presents the array of geomorphic responses to a short duration (time to peak of < 8 h) but high magnitude flood that was the twentieth century flood of record for numerous watersheds. We present herein the geomorphic imprint of Tropical Storm Irene flooding within a larger context of fluvial theory concerning the role of, and trade-off between, the magnitude of energy expenditure during a flood and its duration. Focusing on a detailed field effort within the 187-km2 Saxtons River basin in southeastern VT, augmented by select sites along the adjacent lower gradient Williams River (291-km2), we elucidate (1) the geomorphic effects of a short duration flood in a humid, well-vegetated landscape; (2) the relationship between geomorphic response and (a) peak stream power, (b) total stream power, and (c) flow duration of stream power above a critical threshold; and (3) the spatial variation of geomorphic effects relative to reach-scale geologic and geomorphic controls. Flooding associated with Tropical Storm Irene ranged from the 1000 year recurrence interval (RI) flood (based on Weibull flood frequency analysis) to the 300 year RI flood (log Pearson Type III). Discharges spawned a peak unit stream power of 712 W/m2 (Saxtons River) and 361 W/m2 (Williams River), with total energy expenditure throughout the event of ~ 16,000 × 103 and 15,000 × 103 J, respectively. For the Saxtons River, channel widening was spatially infrequent and limited in magnitude; however, other geomorphic effects were profound (1) the entrainment, transport, and deposition of extremely coarse material; (2) stripping of floodplain surfaces; (3) channel avulsions and incision into Pleistocene-aged material; and (4) deposition of coarse material across floodplains. Based on our extensive field data and hydrologic/hydraulic analyses, we contend that short duration, high energy flows can have profound sedimentological effects but have limited erosive, channel widening impacts. Gravel entrainment and deposition of a catastrophic nature can certainly occur under these flow regimes, but the impacts of these extreme flows on channel geometry may have limited expression.

Unconventional Rotor Power Response to Yaw Error Variations

DOE PAGES

Schreck, S. J.; Schepers, J. G.

2014-12-16

Continued inquiry into rotor and blade aerodynamics remains crucial for achieving accurate, reliable prediction of wind turbine power performance under yawed conditions. To exploit key advantages conferred by controlled inflow conditions, we used EU-JOULE DATA Project and UAE Phase VI experimental data to characterize rotor power production under yawed conditions. Anomalies in rotor power variation with yaw error were observed, and the underlying fluid dynamic interactions were isolated. Unlike currently recognized influences caused by angled inflow and skewed wake, which may be considered potential flow interactions, these anomalies were linked to pronounced viscous and unsteady effects.

High Power Helicon Plasma Source for Plasma Processing

NASA Astrophysics Data System (ADS)

Prager, James; Ziemba, Timothy; Miller, Kenneth E.

2015-09-01

Eagle Harbor Technologies (EHT), Inc. is developing a high power helicon plasma source. The high power nature and pulsed neutral gas make this source unique compared to traditional helicon source. These properties produce a plasma flow along the magnetic field lines, and therefore allow the source to be decoupled from the reaction chamber. Neutral gas can be injected downstream, which allows for precision control of the ion-neutral ratio at the surface of the sample. Although operated at high power, the source has demonstrated very low impurity production. This source has applications to nanoparticle productions, surface modification, and ionized physical vapor deposition.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zamzam, Ahmed, S.; Zhaoy, Changhong; Dall'Anesey, Emiliano

This paper examines the AC Optimal Power Flow (OPF) problem for multiphase distribution networks featuring renewable energy resources (RESs). We start by outlining a power flow model for radial multiphase systems that accommodates wye-connected and delta-connected RESs and non-controllable energy assets. We then formalize an AC OPF problem that accounts for both types of connections. Similar to various AC OPF renditions, the resultant problem is a non convex quadratically-constrained quadratic program. However, the so-called Feasible Point Pursuit-Successive Convex Approximation algorithm is leveraged to obtain a feasible and yet locally-optimal solution. The merits of the proposed solution approach are demonstrated usingmore » two unbalanced multiphase distribution feeders with both wye and delta connections.« less

REGULATOR FOR CALUTRON ION SOURCE

DOEpatents

Miller, B.F.

1958-09-01

Improvements are described in electric discharge devices and circuits for a calutron and, more specifically, presents an arc discharge regulator circuit for the ion source of the calatron. In general, the source comprises a filament which bombards a cathode with electrons, a griid control electrode between the filament and the cathode, and an anode electrode. The control electrode has a DC potential which is varied in response to changes in the anode current flow by means of a saturable reactor installed in its power supply energizing line having the anode current flowing through its control winding. In this manner the bombardment current to the cathode may be decreased when the anode current increases beyond a predetermined level.

78 FR 71594 - Free Flow Power Missouri 2, LLC; Notice of Application Tendered for Filing With the Commission...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-29

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13703-002] Free Flow Power.... c. Date filed: November 13, 2013. d. Applicant: Free Flow Power Missouri 2, LLC. e. Name of Project... President of Project Development, Free Flow Power Corporation, 239 Causeway Street, Suite 300, Boston, MA...

78 FR 71596 - Free Flow Power Missouri 2, LLC; Notice of Application Tendered for Filing With the Commission...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-29

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13704-002] Free Flow Power.... c. Date Filed: November 13, 2013. d. Applicant: Free Flow Power Missouri 2, LLC. e. Name of Project... Feldman, Vice President of Project Development, Free Flow Power Corporation, 239 Causeway Street, Suite...

78 FR 71593 - Free Flow Power Missouri 2, LLC; Notice of Application Tendered for Filing With the Commission...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-29

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13702-002] Free Flow Power.... c. Date filed: November 13, 2013. d. Applicant: Free Flow Power Missouri 2, LLC. e. Name of Project... President of Project Development, Free Flow Power Corporation, 239 Causeway Street, Suite 300, Boston, MA...

78 FR 71592 - Free Flow Power Missouri 2, LLC; Notice of Application Tendered for Filing With the Commission...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-11-29

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Project No. 13701-002] Free Flow Power.... c. Date filed: November 13, 2013. d. Applicant: Free Flow Power Missouri 2, LLC. e. Name of Project..., Vice President of Project Development, Free Flow Power Corporation, 239 Causeway Street, Suite 300...

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

PubMed

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.

Strategies for Voltage Control and Transient Stability Assessment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hiskens, Ian A.

As wind generation grows, its influence on power system performance will becoming increasingly noticeable. Wind generation di ffers from traditional forms of generation in numerous ways though, motivating the need to reconsider the usual approaches to power system assessment and performance enhancement. The project has investigated the impact of wind generation on transient stability and voltage control, identifying and addressing issues at three distinct levels of the power system: 1) at the device level, the physical characteristics of wind turbine generators (WTGs) are quite unlike those of synchronous machines, 2) at the wind-farm level, the provision of reactive support ismore » achieved through coordination of numerous dissimilar devices, rather than straightforward generator control, and 3) from a systems perspective, the location of wind-farms on the sub-transmission network, coupled with the variability inherent in their power output, can cause complex voltage control issues. The project has sought to develop a thorough understanding of the dynamic behaviour of type-3 WTGs, and in particular the WECC generic model. The behaviour of such models is governed by interactions between the continuous dynamics of state variables and discrete events associated with limits. It was shown that these interactions can be quite complex, and may lead to switching deadlock that prevents continuation of the trajectory. Switching hysteresis was proposed for eliminating deadlock situations. Various type-3 WTG models include control blocks that duplicate integrators. It was shown that this leads to non-uniqueness in the conditions governing steady-state, and may result in pre- and post-disturbance equilibria not coinciding. It also gives rise to a zero eigenvalue in the linearized WTG model. In order to eliminate the anomalous behaviour revealed through this investigation, WECC has now released a new generic model for type-3 WTGs. Wind-farms typically incorporate a variety of voltage control equipment including tapchanging transformers, switched capacitors, SVCs, STATCOMs and the WTGs themselves. The project has considered the coordinated control of this equipment, and has addressed a range of issues that arise in wind-farm operation. The first concerns the ability of WTGs to meet reactive power requirements when voltage saturation in the collector network restricts the reactive power availability of individual generators. Secondly, dynamic interactions between voltage regulating devices have been investigated. It was found that under certain realistic conditions, tap-changing transformers may exhibit instability. In order to meet cost, maintenance, fault tolerance and other requirements, it is desirable for voltage control equipment to be treated as an integrated system rather than as independent devices. The resulting high-level scheduling of wind-farm reactive support has been investigated. In addressing this control problem, several forms of future information were considered, including exact future knowledge and stochastic predictions. Deterministic and Stochastic Dynamic Programming techniques were used in the development of control algorithms. The results demonstrated that while exact future knowledge is very useful, simple prediction methods yield little bene fit. The integration of inherently variable wind generation into weak grids, particularly subtransmission networks that are characterized by low X=R ratios, aff ects bus voltages, regulating devices and line flows. The meshed structure of these networks adds to the complexity, especially when wind generation is distributed across multiple nodes. A range of techniques have been considered for analyzing the impact of wind variability on weak grids. Sensitivity analysis, based on the power-flow Jacobian, was used to highlight sections of a system that are most severely a ffected by wind-power variations. A continuation power flow was used to determine parameter changes that reduce the impact of wind-power variability. It was also used to explore interactions between multiple wind-farms. Furthermore, these tools have been used to examine the impact of wind injection on transformer tap operation in subtransmission networks. The results of a tap operation simulation study show that voltage regulation at wind injection nodes increases tap change operations. The tradeo ff between local voltage regulation and tap change frequency is fundamentally important in optimizing the size of reactive compensation used for voltage regulation at wind injection nodes. Line congestion arising as a consequence of variable patterns of wind-power production has also been investigated. Two optimization problems have been formulated, based respectively on the DC and AC power flow models, for identifying vulnerable line segments. The DC optimization is computationally more e fficient, whereas the AC sensitivity-based optimization provides greater accuracy.« less

Experimental Investigation of a Direct-drive Hall Thruster and Solar Array System at Power Levels up to 10 kW

NASA Technical Reports Server (NTRS)

Snyder, John S.; Brophy, John R.; Hofer, Richard R.; Goebel, Dan M.; Katz, Ira

2012-01-01

As NASA considers future exploration missions, high-power solar-electric propulsion (SEP) plays a prominent role in achieving many mission goals. Studies of high-power SEP systems (i.e. tens to hundreds of kilowatts) suggest that significant mass savings may be realized by implementing a direct-drive power system, so NASA recently established the National Direct-Drive Testbed to examine technical issues identified by previous investigations. The testbed includes a 12-kW solar array and power control station designed to power single and multiple Hall thrusters over a wide range of voltages and currents. In this paper, single Hall thruster operation directly from solar array output at discharge voltages of 200 to 450 V and discharge powers of 1 to 10 kW is reported. Hall thruster control and operation is shown to be simple and no different than for operation on conventional power supplies. Thruster and power system electrical oscillations were investigated over a large range of operating conditions and with different filter capacitances. Thruster oscillations were the same as for conventional power supplies, did not adversely affect solar array operation, and were independent of filter capacitance from 8 to 80 ?F. Solar array current and voltage oscillations were very small compared to their mean values and showed a modest dependence on capacitor size. No instabilities or anomalous behavior were observed in the thruster or power system at any operating condition investigated, including near and at the array peak power point. Thruster startup using the anode propellant flow as the power 'switch' was shown to be simple and reliable with system transients mitigated by the proper selection of filter capacitance size. Shutdown via cutoff of propellant flow was also demonstrated. A simple electrical circuit model was developed and is shown to have good agreement with the experimental data.

Airfoil/Wing Flow Control Using Flexible Extended Trailing Edge

DTIC Science & Technology

2009-02-27

and (b) Power spectrums of drag coefficient Figure 4. Mean velocity profiles O Baseline NACA0012. AoA 18 deg c Baseline NACA0012. AoA 20...dynamics, (a) fin amplitude and (b) power spectrum of fin amplitude Development of Computational Tools Simulations of the time-dependent deformation of...combination of experimental, computational and theoretical methods. Compared with Gurney flap and conventional flap, this device enhanced lift at a smaller

An enhanced SOCP-based method for feeder load balancing using the multi-terminal soft open point in active distribution networks

DOE PAGES

Ji, Haoran; Wang, Chengshan; Li, Peng; ...

2017-09-20

The integration of distributed generators (DGs) exacerbates the feeder power flow fluctuation and load unbalanced condition in active distribution networks (ADNs). The unbalanced feeder load causes inefficient use of network assets and network congestion during system operation. The flexible interconnection based on the multi-terminal soft open point (SOP) significantly benefits the operation of ADNs. The multi-terminal SOP, which is a controllable power electronic device installed to replace the normally open point, provides accurate active and reactive power flow control to enable the flexible connection of feeders. An enhanced SOCP-based method for feeder load balancing using the multi-terminal SOP is proposedmore » in this paper. Furthermore, by regulating the operation of the multi-terminal SOP, the proposed method can mitigate the unbalanced condition of feeder load and simultaneously reduce the power losses of ADNs. Then, the original non-convex model is converted into a second-order cone programming (SOCP) model using convex relaxation. In order to tighten the SOCP relaxation and improve the computation efficiency, an enhanced SOCP-based approach is developed to solve the proposed model. Finally, case studies are performed on the modified IEEE 33-node system to verify the effectiveness and efficiency of the proposed method.« less

An enhanced SOCP-based method for feeder load balancing using the multi-terminal soft open point in active distribution networks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ji, Haoran; Wang, Chengshan; Li, Peng

The integration of distributed generators (DGs) exacerbates the feeder power flow fluctuation and load unbalanced condition in active distribution networks (ADNs). The unbalanced feeder load causes inefficient use of network assets and network congestion during system operation. The flexible interconnection based on the multi-terminal soft open point (SOP) significantly benefits the operation of ADNs. The multi-terminal SOP, which is a controllable power electronic device installed to replace the normally open point, provides accurate active and reactive power flow control to enable the flexible connection of feeders. An enhanced SOCP-based method for feeder load balancing using the multi-terminal SOP is proposedmore » in this paper. Furthermore, by regulating the operation of the multi-terminal SOP, the proposed method can mitigate the unbalanced condition of feeder load and simultaneously reduce the power losses of ADNs. Then, the original non-convex model is converted into a second-order cone programming (SOCP) model using convex relaxation. In order to tighten the SOCP relaxation and improve the computation efficiency, an enhanced SOCP-based approach is developed to solve the proposed model. Finally, case studies are performed on the modified IEEE 33-node system to verify the effectiveness and efficiency of the proposed method.« less

Evaluation of the Lattice-Boltzmann Equation Solver PowerFLOW for Aerodynamic Applications

NASA Technical Reports Server (NTRS)

Lockard, David P.; Luo, Li-Shi; Singer, Bart A.; Bushnell, Dennis M. (Technical Monitor)

2000-01-01

A careful comparison of the performance of a commercially available Lattice-Boltzmann Equation solver (Power-FLOW) was made with a conventional, block-structured computational fluid-dynamics code (CFL3D) for the flow over a two-dimensional NACA-0012 airfoil. The results suggest that the version of PowerFLOW used in the investigation produced solutions with large errors in the computed flow field; these errors are attributed to inadequate resolution of the boundary layer for reasons related to grid resolution and primitive turbulence modeling. The requirement of square grid cells in the PowerFLOW calculations limited the number of points that could be used to span the boundary layer on the wing and still keep the computation size small enough to fit on the available computers. Although not discussed in detail, disappointing results were also obtained with PowerFLOW for a cavity flow and for the flow around a generic helicopter configuration.

Transient Characteristics of Free Piston Vuilleurnier Cycle Heat Pumps

NASA Astrophysics Data System (ADS)

Matsue, Junji; Fujimoto, Norioki; Shirai, Hiroyuki

A dynamic analysis of a free piston Vuilleumier cycle heat pump was performed using a time-stepping integration method to investigate transient characteristics under power controlling. The nonlinear relationship between displacement and force for pistons was taken into account for the motion of reciprocating components. The force for pistons is mainly caused by the pressure change of working gas varying with piston displacements; moreover nonlinear viscous dissipative force due to the oscillating flow of working gas in heat exchangers and discontinuous damping force caused by solid friction at piston seals and rod seals are included. The displacements of pistons and pressure changes in the Vuilleumier cycle heat pump were integrated by an ideal isothermal thermodynamic relationship. It was assumed that the flow friction was proportional to the kinematic pressure of working gas, and that the solid friction at the seals was due to the functions of the working gas pressure and the tension of seal springs. In order to investigate the transient characteristics of a proposed free piston Vuilleumier cycle heat pump machine when hot-side working gas temperatures and alternate force were changed, some calculations were performed and discussed. These calculation results make clear transient characteristics at starting and power controlling. It was further found that only a small amount of starter power is required in particular conditions. During controlling, the machine becomes unstable when there is ar elatively large reduction in cooling or heating power. Therefore, an auxiliary device is additionally needed to obtain stable operation, such as al inear motor.

Silane-Pyrolysis Reactor With Nonuniform Heating

NASA Technical Reports Server (NTRS)

Iya, Sridhar K.

1991-01-01

Improved reactor serves as last stage in system processing metallurgical-grade silicon feedstock into silicon powder of ultrahigh purity. Silane pyrolized to silicon powder and hydrogen gas via homogeneous decomposition reaction in free space. Features set of individually adjustable electrical heaters and purge flow of hydrogen to improve control of pyrolysis conditions. Power supplied to each heater set in conjunction with flow in reactor to obtain desired distribution of temperature as function of position along reactor.

Control of the probe influence on the flow field in LP steam turbine

NASA Astrophysics Data System (ADS)

Kolovratník, Michal; Yun, Kukchol; Bartoš, Ondřej

For measuring the fine droplets properties in the wet steam expanding in the steam turbines the light extinction probes are usually used. The paper presents CFD modelling of the extinction probe influence on the wet steam flow field at the measurement position. The aim is to get a basic information about the influence of the flow field deviation on the measured data, in other words, of necessity to correct the measured data. The basic modelling procedure is described, as well as the supposed simplifications and the factor considering the change in the steam density in the measuring slot of the probe. The model is based on the experimental data that were achieved during the developmental measurements in the steam turbine 1090 MW in the power station Temelín. The experimental measurement was done in the cooperation with the Doosan Škoda Power s.r.o.

Range of control of cardiovascular variables by the hypothalamus

NASA Technical Reports Server (NTRS)

Smith, O. A.; Stephenson, R. B.; Randall, D. C.

1974-01-01

New methodologies were utilized to study the influence of the hypothalamus on the cardiovascular system. The regulation of myocardial activity was investigated in monkeys with hypothalamic lesions that eliminate cardiovascular responses. Observations showed that a specific part of the hypothalamus regulates changes in myocardial contractility that accompanies emotion. Studies of the hypothalamus control of renal blood flow showed the powerful potential control of this organ over renal circulation.

Remotely powered distributed microfluidic pumps and mixers based on miniature diodes.

PubMed

Chang, Suk Tai; Beaumont, Erin; Petsev, Dimiter N; Velev, Orlin D

2008-01-01

We demonstrate new principles of microfluidic pumping and mixing by electronic components integrated into a microfluidic chip. The miniature diodes embedded into the microchannel walls rectify the voltage induced between their electrodes from an external alternating electric field. The resulting electroosmotic flows, developed in the vicinity of the diode surfaces, were utilized for pumping or mixing of the fluid in the microfluidic channel. The flow velocity of liquid pumped by the diodes facing in the same direction linearly increased with the magnitude of the applied voltage and the pumping direction could be controlled by the pH of the solutions. The transverse flow driven by the localized electroosmotic flux between diodes oriented oppositely on the microchannel was used in microfluidic mixers. The experimental results were interpreted by numerical simulations of the electrohydrodynamic flows. The techniques may be used in novel actively controlled microfluidic-electronic chips.

The Effect of Flow Distribution on the Concentration of NO Produced by Pulsed Arc Discharge

NASA Astrophysics Data System (ADS)

Hu, Hui; Bao, Bin; Wang, Heli; Liang, Haiyan; He, Junjia; He, Zhenghao; Li, Jin

2007-12-01

As a new method to cure acute respiratory distress syndrome (ARDS), high blood pressure and some illnesses related to the lung, NO has recently received more attention. Thermal plasmas produced by arc discharge can create medical NO, but the concentration of NO2 produced by arc discharge must be controlled simultaneously. This paper investigates the characteristics and regulations of NO production at different flow distribution by pulsed arc discharge in dry air with a special pulsed power. The experimental results show that the flow distribution has a considerable effect on the NO concentration, the stabilization of NO. The production of NO2 could be controlled and the ratio of NO2/NO was decreased to about 10% in the arc discharge. Therefore, the arc discharge could produce stable inhaled NO for medical treatment by changing the flow distribution.

Effect of water chemistry upsets on the dynamics of corrective reagent dosing systems at thermal power stations

NASA Astrophysics Data System (ADS)

Voronov, V. N.; Yegoshina, O. V.; Bolshakova, N. A.; Yarovoi, V. O.; Latt, Aie Min

2016-12-01

Typical disturbances in the dynamics of a corrective reagent dosing system under unsteady-state conditions during the unsatisfactory operation of a chemical control system with some water chemistry upsets at thermal and nuclear power stations are considered. An experimental setup representing a physical model for the water chemistry control system is described. The two disturbances, which are most frequently encountered in water chemistry control practice, such as a breakdown or shutdown of temperature compensation during pH measurement and an increase in the heat-transfer fluid flow rate, have been modeled in the process of study. The study of the effect produced by the response characteristics of chemical control analyzers on the operation of a reagent dosing system under unsteady-state conditions is important for the operative control of a water chemistry regime state. The effect of temperature compensation during pH measurement on the dynamics of an ammonia-dosing system in the manual and automatic cycle chemistry control modes has been studied. It has been demonstrated that the reading settling time of a pH meter in the manual ammonia- dosing mode grows with a breakdown in temperature compensation and a simultaneous increase in the temperature of a heat-transfer fluid sample. To improve the efficiency of water chemistry control, some systems for the quality control of a heat-transfer fluid by a chemical parameter with the obligatory compensation of a disturbance in its flow rate have been proposed for use. Experimental results will possibly differ from industrial data due to a great length of sampling lines. For this reason, corrective reagent dosing systems must be adapted to the conditions of a certain power-generating unit in the process of their implementation.

REACTOR

DOEpatents

Roman, W.G.

1961-06-27

A pressurized water reactor in which automatic control is achieved by varying the average density of the liquid moderator-cooiant is patented. Density is controlled by the temperature and power level of the reactor ftself. This control can be effected by the use of either plate, pellet, or tubular fuel elements. The fuel elements are disposed between upper and lower coolant plenum chambers and are designed to permit unrestricted coolant flow. The control chamber has an inlet opening communicating with the lower coolant plenum chamber and a restricted vapor vent communicating with the upper coolant plenum chamber. Thus, a variation in temperature of the fuel elements will cause a variation in the average moderator density in the chamber which directly affects the power level of the reactor.

Development of model reference adaptive control theory for electric power plant control applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mabius, L.E.

1982-09-15

The scope of this effort includes the theoretical development of a multi-input, multi-output (MIMO) Model Reference Control (MRC) algorithm, (i.e., model following control law), Model Reference Adaptive Control (MRAC) algorithm and the formulation of a nonlinear model of a typical electric power plant. Previous single-input, single-output MRAC algorithm designs have been generalized to MIMO MRAC designs using the MIMO MRC algorithm. This MRC algorithm, which has been developed using Command Generator Tracker methodologies, represents the steady state behavior (in the adaptive sense) of the MRAC algorithm. The MRC algorithm is a fundamental component in the MRAC design and stability analysis.more » An enhanced MRC algorithm, which has been developed for systems with more controls than regulated outputs, alleviates the MRC stability constraint of stable plant transmission zeroes. The nonlinear power plant model is based on the Cromby model with the addition of a governor valve management algorithm, turbine dynamics and turbine interactions with extraction flows. An application of the MRC algorithm to a linearization of this model demonstrates its applicability to power plant systems. In particular, the generated power changes at 7% per minute while throttle pressure and temperature, reheat temperature and drum level are held constant with a reasonable level of control. The enhanced algorithm reduces significantly control fluctuations without modifying the output response.« less

Extension of vibrational power flow techniques to two-dimensional structures

NASA Technical Reports Server (NTRS)

Cuschieri, Joseph M.

1988-01-01

In the analysis of the vibration response and structure-borne vibration transmission between elements of a complex structure, statistical energy analysis (SEA) or finite element analysis (FEA) are generally used. However, an alternative method is using vibrational power flow techniques which can be especially useful in the mid frequencies between the optimum frequency regimes for SEA and FEA. Power flow analysis has in general been used on 1-D beam-like structures or between structures with point joints. In this paper, the power flow technique is extended to 2-D plate-like structures joined along a common edge without frequency or spatial averaging the results, such that the resonant response of the structure is determined. The power flow results are compared to results obtained using FEA results at low frequencies and SEA at high frequencies. The agreement with FEA results is good but the power flow technique has an improved computational efficiency. Compared to the SEA results the power flow results show a closer representation of the actual response of the structure.

Extension of vibrational power flow techniques to two-dimensional structures

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.

1987-01-01

In the analysis of the vibration response and structure-borne vibration transmission between elements of a complex structure, statistical energy analysis (SEA) or Finite Element Analysis (FEA) are generally used. However, an alternative method is using vibrational power flow techniques which can be especially useful in the mid- frequencies between the optimum frequency regimes for FEA and SEA. Power flow analysis has in general been used on one-dimensional beam-like structures or between structures with point joints. In this paper, the power flow technique is extended to two-dimensional plate like structures joined along a common edge without frequency or spatial averaging the results, such that the resonant response of the structure is determined. The power flow results are compared to results obtained using FEA at low frequencies and SEA at high frequencies. The agreement with FEA results is good but the power flow technique has an improved computational efficiency. Compared to the SEA results the power flow results show a closer representation of the actual response of the structure.

Electro-osmotically driven liquid delivery method and apparatus

DOEpatents

Rakestraw, David J.; Anex, Deon S.; Yan, Chao; Dadoo, Rajeev; Zare, Richard N.

1999-01-01

Method and apparatus for controlling precisely the composition and delivery of liquid at sub-.mu.L/min flow rate. One embodiment of such a delivery system is an electro-osmotically driven gradient flow delivery system that generates dynamic gradient flows with sub-.mu.L/min flow rates by merging a plurality of electro-osmotic flows. These flows are delivered by a plurality of delivery arms attached to a mixing connector, where they mix and then flow into a receiving means, preferably a column. Each inlet of the plurality of delivery arms is placed in a corresponding solution reservoir. A plurality of independent programmable high-voltage power supplies is used to apply a voltage program to each of the plurality of solution reservoirs to regulate the electro-osmotic flow in each delivery arm. The electro-osmotic flow rates in the delivery arms are changed with time according to each voltage program to deliver the required gradient profile to the column.

Gas Flow Detection System

NASA Technical Reports Server (NTRS)

Moss, Thomas; Ihlefeld, Curtis; Slack, Barry

2010-01-01

This system provides a portable means to detect gas flow through a thin-walled tube without breaking into the tubing system. The flow detection system was specifically designed to detect flow through two parallel branches of a manifold with only one inlet and outlet, and is a means for verifying a space shuttle program requirement that saves time and reduces the risk of flight hardware damage compared to the current means of requirement verification. The prototype Purge Vent and Drain Window Cavity Conditioning System (PVD WCCS) Flow Detection System consists of a heater and a temperature-sensing thermistor attached to a piece of Velcro to be attached to each branch of a WCCS manifold for the duration of the requirement verification test. The heaters and thermistors are connected to a shielded cable and then to an electronics enclosure, which contains the power supplies, relays, and circuit board to provide power, signal conditioning, and control. The electronics enclosure is then connected to a commercial data acquisition box to provide analog to digital conversion as well as digital control. This data acquisition box is then connected to a commercial laptop running a custom application created using National Instruments LabVIEW. The operation of the PVD WCCS Flow Detection System consists of first attaching a heater/thermistor assembly to each of the two branches of one manifold while there is no flow through the manifold. Next, the software application running on the laptop is used to turn on the heaters and to monitor the manifold branch temperatures. When the system has reached thermal equilibrium, the software application s graphical user interface (GUI) will indicate that the branch temperatures are stable. The operator can then physically open the flow control valve to initiate the test flow of gaseous nitrogen (GN2) through the manifold. Next, the software user interface will be monitored for stable temperature indications when the system is again at thermal equilibrium with the test flow of GN2. The temperature drop of each branch from its "no flow" stable temperature peak to its stable "with flow" temperature will allow the operator to determine whether a minimum level of flow exists. An alternative operation has the operator turning on the software only long enough to record the ambient temperature of the tubing before turning on the heaters and initiating GN2 flow. The stable temperature of the heated tubing with GN2 flow is then compared with the ambient tubing temperature to determine if flow is present in each branch. To help quantify the level of flow in the manifolds, each branch will be bench calibrated to establish its thermal properties using the flow detection system and different flow rates. These calibration values can then be incorporated into the software application to provide more detailed flow rate information.

Circuit with a Switch for Charging a Battery in a Battery Capacitor Circuit

NASA Technical Reports Server (NTRS)

Stuart, Thomas A. (Inventor); Ashtiani, Cyrus N. (Inventor)

2008-01-01

A circuit for charging a battery combined with a capacitor includes a power supply adapted to be connected to the capacitor, and the battery. The circuit includes an electronic switch connected to the power supply. The electronic switch is responsive to switch between a conducting state to allow current and a non-conducting state to prevent current flow. The circuit includes a control device connected to the switch and is operable to generate a control signal to continuously switch the electronic switch between the conducting and non-conducting states to charge the battery.

Transonic Flutter Suppression Control Law Design, Analysis and Wind-Tunnel Results

NASA Technical Reports Server (NTRS)

Mukhopadhyay, Vivek

1999-01-01

The benchmark active controls technology and wind tunnel test program at NASA Langley Research Center was started with the objective to investigate the nonlinear, unsteady aerodynamics and active flutter suppression of wings in transonic flow. The paper will present the flutter suppression control law design process, numerical nonlinear simulation and wind tunnel test results for the NACA 0012 benchmark active control wing model. The flutter suppression control law design processes using classical, and minimax techniques are described. A unified general formulation and solution for the minimax approach, based on the steady state differential game theory is presented. Design considerations for improving the control law robustness and digital implementation are outlined. It was shown that simple control laws when properly designed based on physical principles, can suppress flutter with limited control power even in the presence of transonic shocks and flow separation. In wind tunnel tests in air and heavy gas medium, the closed-loop flutter dynamic pressure was increased to the tunnel upper limit of 200 psf. The control law robustness and performance predictions were verified in highly nonlinear flow conditions, gain and phase perturbations, and spoiler deployment. A non-design plunge instability condition was also successfully suppressed.

Smart house-based optimal operation of thermal unit commitment for a smart grid considering transmission constraints

NASA Astrophysics Data System (ADS)

Howlader, Harun Or Rashid; Matayoshi, Hidehito; Noorzad, Ahmad Samim; Muarapaz, Cirio Celestino; Senjyu, Tomonobu

2018-05-01

This paper presents a smart house-based power system for thermal unit commitment programme. The proposed power system consists of smart houses, renewable energy plants and conventional thermal units. The transmission constraints are considered for the proposed system. The generated power of the large capacity renewable energy plant leads to the violated transmission constraints in the thermal unit commitment programme, therefore, the transmission constraint should be considered. This paper focuses on the optimal operation of the thermal units incorporated with controllable loads such as Electrical Vehicle and Heat Pump water heater of the smart houses. The proposed method is compared with the power flow in thermal units operation without controllable loads and the optimal operation without the transmission constraints. Simulation results show the validation of the proposed method.

Low-Pressure Long-Term Xenon Storage for Electric Propulsion

NASA Technical Reports Server (NTRS)

Back, Dwight D.; Ramos, Charlie; Meyer, John A.

2001-01-01

This Phase 2 effort demonstrated an alternative Xe storage and regulation system using activated carbon (AC) as a secondary storage media (ACSFR). This regulator system is nonmechanical, simple, inexpensive, and lighter. The ACSFR system isolates the thruster from the compressed gas tank, and allows independent multiple setpoint thruster operation. The flow using an ACSFR can also be throttled by applying increments in electrical power. Primary storage of Xe by AC is not superior to compressed gas storage with regard to weight, but AC storage can provide volume reduction, lower pressures in space, and potentially in situ Xe purification. With partial fill designs, a primary AC storage vessel for Xe could also eliminate problems with two-phase storage and regulate pressure. AC could also be utilized in long-term large quantity storage of Xe serving as a compact capture site for boil-off. Several Xe delivery ACSFR protocols between 2 and 45 sccm, and 15 min to 7 hr, were tested with an average flow variance of 1.2 percent, average power requirements of 5 W, and repeatability s of about 0.4 percent. Power requirements are affected by ACSFR bed sizing and flow rate/ duration design points, and these flow variances can be reduced by optimizing PID controller parameters.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schreck, S. J.; Schepers, J. G.

Continued inquiry into rotor and blade aerodynamics remains crucial for achieving accurate, reliable prediction of wind turbine power performance under yawed conditions. To exploit key advantages conferred by controlled inflow conditions, we used EU-JOULE DATA Project and UAE Phase VI experimental data to characterize rotor power production under yawed conditions. Anomalies in rotor power variation with yaw error were observed, and the underlying fluid dynamic interactions were isolated. Unlike currently recognized influences caused by angled inflow and skewed wake, which may be considered potential flow interactions, these anomalies were linked to pronounced viscous and unsteady effects.

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

NASA Astrophysics Data System (ADS)

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.

Upgrade of the gas flow control system of the resistive current leads of the LHC inner triplet magnets: Simulation and experimental validation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Perin, A.; Casas-Cubillos, J.; Pezzetti, M.

2014-01-29

The 600 A and 120 A circuits of the inner triplet magnets of the Large Hadron Collider are powered by resistive gas cooled current leads. The current solution for controlling the gas flow of these leads has shown severe operability limitations. In order to allow a more precise and more reliable control of the cooling gas flow, new flowmeters will be installed during the first long shutdown of the LHC. Because of the high level of radiation in the area next to the current leads, the flowmeters will be installed in shielded areas located up to 50 m away frommore » the current leads. The control valves being located next to the current leads, this configuration leads to long piping between the valves and the flowmeters. In order to determine its dynamic behaviour, the proposed system was simulated with a numerical model and validated with experimental measurements performed on a dedicated test bench.« less

Finite size scaling analysis on Nagel-Schreckenberg model for traffic flow

NASA Astrophysics Data System (ADS)

Balouchi, Ashkan; Browne, Dana

2015-03-01

The traffic flow problem as a many-particle non-equilibrium system has caught the interest of physicists for decades. Understanding the traffic flow properties and though obtaining the ability to control the transition from the free-flow phase to the jammed phase plays a critical role in the future world of urging self-driven cars technology. We have studied phase transitions in one-lane traffic flow through the mean velocity, distributions of car spacing, dynamic susceptibility and jam persistence -as candidates for an order parameter- using the Nagel-Schreckenberg model to simulate traffic flow. The length dependent transition has been observed for a range of maximum velocities greater than a certain value. Finite size scaling analysis indicates power-law scaling of these quantities at the onset of the jammed phase.

Emissions-critical charge cooling using an organic rankine cycle

DOEpatents

Ernst, Timothy C.; Nelson, Christopher R.

2014-07-15

The disclosure provides a system including a Rankine power cycle cooling subsystem providing emissions-critical charge cooling of an input charge flow. The system includes a boiler fluidly coupled to the input charge flow, an energy conversion device fluidly coupled to the boiler, a condenser fluidly coupled to the energy conversion device, a pump fluidly coupled to the condenser and the boiler, an adjuster that adjusts at least one parameter of the Rankine power cycle subsystem to change a temperature of the input charge exiting the boiler, and a sensor adapted to sense a temperature characteristic of the vaporized input charge. The system includes a controller that can determine a target temperature of the input charge sufficient to meet or exceed predetermined target emissions and cause the adjuster to adjust at least one parameter of the Rankine power cycle to achieve the predetermined target emissions.

Oscillatory motion based measurement method and sensor for measuring wall shear stress due to fluid flow

DOEpatents

Armstrong, William D [Laramie, WY; Naughton, Jonathan [Laramie, WY; Lindberg, William R [Laramie, WY

2008-09-02

A shear stress sensor for measuring fluid wall shear stress on a test surface is provided. The wall shear stress sensor is comprised of an active sensing surface and a sensor body. An elastic mechanism mounted between the active sensing surface and the sensor body allows movement between the active sensing surface and the sensor body. A driving mechanism forces the shear stress sensor to oscillate. A measuring mechanism measures displacement of the active sensing surface relative to the sensor body. The sensor may be operated under periodic excitation where changes in the nature of the fluid properties or the fluid flow over the sensor measurably changes the amplitude or phase of the motion of the active sensing surface, or changes the force and power required from a control system in order to maintain constant motion. The device may be operated under non-periodic excitation where changes in the nature of the fluid properties or the fluid flow over the sensor change the transient motion of the active sensor surface or change the force and power required from a control system to maintain a specified transient motion of the active sensor surface.

Numerical and in-situ investigations of water hammer effects in Drava river Kaplan turbine hydropower plants

NASA Astrophysics Data System (ADS)

Bergant, A.; Gregorc, B.; Gale, J.

2012-11-01

This paper deals with critical flow regimes that may induce unacceptable water hammer in Kaplan turbine hydropower plants. Water hammer analysis should be performed for normal, emergency and catastrophic operating conditions. Hydropower plants with Kaplan turbines are usually comprised of relatively short inlet and outlet conduits. The rigid water hammer theory can be used for this case. For hydropower plants with long penstocks the elastic water hammer should be used. Some Kaplan turbine units are installed in systems with long open channels. In this case, water level oscillations in the channels should be carefully investigated. Computational results are compared with results of measurements in recently rehabilitated seven Drava river hydroelectric power plants in Slovenia. Water hammer in the six power plants is controlled by appropriate adjustment of the wicket gates and runner blades closing/opening manoeuvres. Due to very long inflow and outflow open channels in Zlatoličje HPP a special vaned pressure regulating device attenuates extreme pressures in Kaplan turbine flow-passage system and controls unsteady flow in both open channels. Comparisons of results include normal operating regimes. The agreement between computed and measured results is reasonable.

SiC MOSFET Based Single Phase Active Boost Rectifier with Power Factor Correction for Wireless Power Transfer Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Onar, Omer C; Tang, Lixin; Chinthavali, Madhu Sudhan

2014-01-01

Wireless Power Transfer (WPT) technology is a novel research area in the charging technology that bridges the utility and the automotive industries. There are various solutions that are currently being evaluated by several research teams to find the most efficient way to manage the power flow from the grid to the vehicle energy storage system. There are different control parameters that can be utilized to compensate for the change in the impedance due to variable parameters such as battery state-of-charge, coupling factor, and coil misalignment. This paper presents the implementation of an active front-end rectifier on the grid side formore » power factor control and voltage boost capability for load power regulation. The proposed SiC MOSFET based single phase active front end rectifier with PFC resulted in >97% efficiency at 137mm air-gap and >95% efficiency at 160mm air-gap.« less

Graph theory applied to noise and vibration control in statistical energy analysis models.

PubMed

Guasch, Oriol; Cortés, Lluís

2009-06-01

A fundamental aspect of noise and vibration control in statistical energy analysis (SEA) models consists in first identifying and then reducing the energy flow paths between subsystems. In this work, it is proposed to make use of some results from graph theory to address both issues. On the one hand, linear and path algebras applied to adjacency matrices of SEA graphs are used to determine the existence of any order paths between subsystems, counting and labeling them, finding extremal paths, or determining the power flow contributions from groups of paths. On the other hand, a strategy is presented that makes use of graph cut algorithms to reduce the energy flow from a source subsystem to a receiver one, modifying as few internal and coupling loss factors as possible.

Power formula for open-channel flow resistance

USGS Publications Warehouse

Chen, Cheng-lung

1988-01-01

This paper evaluates various power formulas for flow resistance in open channels. Unlike the logarithmic resistance equation that can be theoretically derived either from Prandtl's mixing-length hypothesis or von Karman's similarity hypothesis, the power formula has long had an appearance of empiricism. Nevertheless, the simplicity in the form of the power formula has made it popular among the many possible forms of flow resistance formulas. This paper reexamines the concept and rationale of the power formulation, thereby addressing some critical issues in the modeling of flow resistance.

[Examination of placental three-dimensional power Doppler indices and perinatal outcome in pregnancies complicated by intrauterine growth restriction].

PubMed

Molnár, András; Surányi, Andrea; Jakó, Mária; Nyári, Tibor; Németh, Gábor

2017-07-01

Development of intrauterine growth restriction (IUGR) can be traced back to maternal or fetal factors, but in many cases we find placental factors (reduced placental circulation) in the background. Our aim was to examine whether the reduced placental bloodperfusion and vascularity show any correlation with cesarean section frequency and the clinical outcome in IUGR pregnancies. The aim of the present study was also to use a properly calibrated and reproducible method for evaluating placental blood flow, that can later be incorporated into the routine examination. 254 women were recruited in our prospective case-control study. The 3 dimensional power Doppler (3DPD) ultrasound indices; vascularisation index (VI), flow index (FI) and vascularization flow index (VFI) were measured on each participant. Median VI was 3.7% (interquartile range [IQR] 3.2%-4.2%) in the IUGR group and 10.1% (IQR 8.6%-10.9%) in the control group (p = 0.001). Median FI value was 40.0 (IQR 39.7-42.5) in the IUGR group and 45.1 (IQR 44.1-53.1) in the control group (p = 0.012). Median VFI was 2.2 (IQR 2.1-2.4) in the IUGR group and 4.8 (IQR 4.4-5.3) in the control. The 3DPD indices may be useful for examining changes in circulation in IUGR pregnancies to characterize the underlying pathology. Orv Hetil. 2017; 158(26): 1008-1013.

Redd dewatering effects on hatching and larval survival of the robust redhorse

USGS Publications Warehouse

Fisk, J. M.; Kwak, Thomas J.; Heise, R. J.; Sessions, F. W.

2013-01-01

Riverine habitats have been altered and fragmented from hydroelectric dams and change spatially and temporally with hydropower flow releases. Hydropeaking flow regimes for electrical power production inundate areas that create temporary suitable habitat for fish that may be rapidly drained. Robust redhorse Moxostoma robustum, an imperiled, rare fish species, uses such temporary habitats to spawn, but when power generation ceases, these areas are dewatered until the next pulse of water is released. We experimentally simulated the effects of dewatering periods on the survival of robust redhorse eggs and larvae in the laboratory. Robust redhorse eggs were placed in gravel in eyeing-hatching jars (three jars per treatment) and subjected to one of four dewatering periods (6, 12, 24 and 48 h), followed by 12 h of inundation for each treatment, and a control treatment was never dewatered. Egg desiccation was observed in some eggs in the 24- and 48-h treatments after one dewatering period. For all treatments except the control, the subsequent dewatering period after eggs hatched was lethal. Larval emergence for the control treatment was observed on day 5 post-hatching and continued until the end of the experiment (day 21). Larval survival was significantly different between the control and all dewatering treatments for individuals in the gravel. These findings support the need for hydropower facilities to set minimum flows to maintain inundation of spawning areas for robust redhorse and other species to reduce dewatering mortality.

Flow Components in a NaK Test Loop Designed to Simulate Conditions in a Nuclear Surface Power Reactor

NASA Astrophysics Data System (ADS)

Polzin, Kurt A.; Godfroy, Thomas J.

2008-01-01

A test loop using NaK as the working fluid is presently in use to study material compatibility effects on various components that comprise a possible nuclear reactor design for use on the lunar surface. A DC electromagnetic (EM) pump has been designed and implemented as a means of actively controlling the NaK flow rate through the system and an EM flow sensor is employed to monitor the developed flow rate. These components allow for the matching of the flow rate conditions in test loops with those that would be found in a full-scale surface-power reactor. The design and operating characteristics of the EM pump and flow sensor are presented. In the EM pump, current is applied to a set of electrodes to produce a Lorentz body force in the fluid. A measurement of the induced voltage (back-EMF) in the flow sensor provides the means of monitoring flow rate. Both components are compact, employing high magnetic field strength neodymium magnets thermally coupled to a water-cooled housing. A vacuum gap limits the heat transferred from the high temperature NaK tube to the magnets and a magnetically-permeable material completes the magnetic circuit. The pump is designed to produce a pressure rise of 34.5 kPa, and the flow sensor's predicted output is roughly 20 mV at the loop's nominal flow rate of 0.114 m3/hr.

Flow Components in a NaK Test Loop Designed to Simulate Conditions in a Nuclear Surface Power Reactor

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.; Godfroy, Thomas J.

2008-01-01

A test loop using NaK as the working fluid is presently in use to study material compatibility effects on various components that comprise a possible nuclear reactor design for use on the lunar surface. A DC electromagnetic (EM) pump has been designed and implemented as a means of actively controlling the NaK flow rate through the system and an EM flow sensor is employed to monitor the developed flow rate. These components allow for the matching of the flow rate conditions in test loops with those that would be found in a full-scale surface-power reactor. The design and operating characteristics of the EM pump and flow sensor are presented. In the EM pump, current is applied to a set of electrodes to produce a Lorentz body force in the fluid. A measurement of the induced voltage (back-EMF) in the flow sensor provides the means of monitoring flow rate. Both components are compact, employing high magnetic field strength neodymium magnets thermally coupled to a water-cooled housing. A vacuum gap limits the heat transferred from the high temperature NaK tube to the magnets and a magnetically-permeable material completes the magnetic circuit. The pump is designed to produce a pressure rise of 5 psi, and the flow sensor's predicted output is roughly 20 mV at the loop's nominal flow rate of 0.5 GPM.

Reinforcement learning techniques for controlling resources in power networks

NASA Astrophysics Data System (ADS)

Kowli, Anupama Sunil

As power grids transition towards increased reliance on renewable generation, energy storage and demand response resources, an effective control architecture is required to harness the full functionalities of these resources. There is a critical need for control techniques that recognize the unique characteristics of the different resources and exploit the flexibility afforded by them to provide ancillary services to the grid. The work presented in this dissertation addresses these needs. Specifically, new algorithms are proposed, which allow control synthesis in settings wherein the precise distribution of the uncertainty and its temporal statistics are not known. These algorithms are based on recent developments in Markov decision theory, approximate dynamic programming and reinforcement learning. They impose minimal assumptions on the system model and allow the control to be "learned" based on the actual dynamics of the system. Furthermore, they can accommodate complex constraints such as capacity and ramping limits on generation resources, state-of-charge constraints on storage resources, comfort-related limitations on demand response resources and power flow limits on transmission lines. Numerical studies demonstrating applications of these algorithms to practical control problems in power systems are discussed. Results demonstrate how the proposed control algorithms can be used to improve the performance and reduce the computational complexity of the economic dispatch mechanism in a power network. We argue that the proposed algorithms are eminently suitable to develop operational decision-making tools for large power grids with many resources and many sources of uncertainty.

Application of laminar flow control to supersonic transport configurations

NASA Technical Reports Server (NTRS)

Parikh, P. G.; Nagel, A. L.

1990-01-01

The feasibility and impact of implementing a laminar flow control system on a supersonic transport configuration were investigated. A hybrid laminar flow control scheme consisting of suction controlled and natural laminar flow was developed for a double-delta type wing planform. The required suction flow rates were determined from boundary layer stability analyses using representative wing pressure distributions. A preliminary design of structural modifications needed to accommodate suction through a perforated titanium skin was carried out together with the ducting and systems needed to collect, compress and discharge the suction air. The benefits of reduced aerodynamic drag were weighed against the weight, volume and power requirement penalties of suction system installation in a mission performance and sizing program to assess the net benefits. The study showed a feasibility of achieving significant laminarization of the wing surface by use of a hybrid scheme, leading to an 8.2 percent reduction in the cruise drag. This resulted in an 8.5 percent reduction in the maximum takeoff weight and a 12 percent reduction in the fuel burn after the inclusion of the LFC system installation penalties. Several research needs were identified for a resolution of aerodynamics, structural and systems issues before these potential benefits could be realized in a practical system.

Guest Editorial Introduction to the Special Issue on 'Advanced Signal Processing Techniques and Telecommunications Network Infrastructures for Smart Grid Analysis, Monitoring, and Management'

DOE PAGES

Bracale, Antonio; Barros, Julio; Cacciapuoti, Angela Sara; ...

2015-06-10

Electrical power systems are undergoing a radical change in structure, components, and operational paradigms, and are progressively approaching the new concept of smart grids (SGs). Future power distribution systems will be characterized by the simultaneous presence of various distributed resources, such as renewable energy systems (i.e., photovoltaic power plant and wind farms), storage systems, and controllable/non-controllable loads. Control and optimization architectures will enable network-wide coordination of these grid components in order to improve system efficiency and reliability and to limit greenhouse gas emissions. In this context, the energy flows will be bidirectional from large power plants to end users andmore » vice versa; producers and consumers will continuously interact at different voltage levels to determine in advance the requests of loads and to adapt the production and demand for electricity flexibly and efficiently also taking into account the presence of storage systems.« less

Control of respiration-driven retrograde flow in the subdiaphragmatic venous return of the Fontan circulation

PubMed Central

Vukicevic, M; Conover, T; Jaeggli, M; Zhou, J; Pennati, G; Hsia, TY; Figliola, RS

2014-01-01

Respiration influences the subdiaphragmatic venous return in the total cavopulmonary connection (TCPC) of the Fontan circulation whereby both the inferior vena cava (IVC) and hepatic vein flows can experience retrograde motion. Controlling retrograde flows could improve patient outcomes. Using a patient-specific model within a Fontan mock circulatory system with respiration, we inserted a valve into the IVC to examine its effects on local hemodynamics while varying retrograde volumes by changing vascular impedances. A bovine valved conduit reduced IVC retrograde flow to within 3% of antegrade flow in all cases. The valve closed only under conditions supporting retrograde flow and its effects on local hemodynamics increased with larger retrograde volume. Liver and TCPC pressures improved only while the valve leaflets were closed while cycle-averaged pressures improved only slightly (italic>1 mm Hg). Increased pulmonary vascular resistance raised mean circulation pressures but the valve functioned and cardiac output improved and stabilized. Power loss across the TCPC improved by 12–15% (pbold>0.05) with a valve. The effectiveness of valve therapy is dependent on patient vascular impedance. PMID:24814833

Flow Control of Liquid Metal Propellants for In-Space Electric Propulsion Systems

NASA Technical Reports Server (NTRS)

Bonds, Kevin W.; Polzin, Kurt A.

2010-01-01

Operation of Hall thrusters with bismuth propellant has been shown to be a promising path for development of high-power (140 kW per thruster), high performance (8000s I(sub sp at >70% efficiency) electric propulsion systems.

40 CFR 51.363 - Quality assurance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... test, the evaporative system tests, and emission control component checks (as applicable); (vi...) A check of the Constant Volume Sampler flow calibration; (5) A check for the optimization of the... selection, and power absorption; (9) A check of the system's ability to accurately detect background...

Robust Fixed-Structure Control

DTIC Science & Technology

1994-10-30

Deterministic Foundation for Statistical Energy Analysis ," J. Sound Vibr., to appear. 1.96 D. S. Bernstein and S. P. Bhat, "Lyapunov Stability, Semistability...S. Bernstein, "Power Flow, Energy Balance, and Statistical Energy Analysis for Large Scale, Interconnected Systems," Proc. Amer. Contr. Conf., pp

The modeling, simulation, and control of transport phenomena in a thermally destabilizing Bridgman crystal growth system

NASA Astrophysics Data System (ADS)

Sonda, Paul Julio

This thesis presents a comprehensive examination of the modeling, simulation, and control of axisymmetric flows occurring in a vertical Bridgman crystal growth system with the melt underlying the crystal. The significant complexity and duration of the manufacturing process make experimental optimization a prohibitive task. Numerical simulation has emerged as a powerful tool in understanding the processing issues still prevalent in industry. A first-principles model is developed to better understand the transport phenomena within a representative vertical Bridgman system. The set of conservation equations for momentum, energy, and species concentration are discretized using the Galerkin finite element method and simulated using accurate time-marching schemes. Simulation results detail the occurrence of fascinating nonlinear dynamics, in the form of stable, time-varying behavior for sufficiently large melt regimes and multiple steady flow states. This discovery of time-periodic flows for high intensity flows is qualitatively consistent with experimental observations. Transient simulations demonstrate that process operating conditions have a marked effect on the hydrodynamic behavior within the melt, which consequently affects the dopant concentration profile within the crystal. The existence of nonlinear dynamical behavior within this system motivates the need for feedback control algorithms which can provide superior crystal quality. This work studies the feasibility of using crucible rotation to control flows in the vertical Bridgman system. Simulations show that crucible rotation acts to suppress the axisymmetric flows. However, for the case when the melt lies below the crystal, crucible rotation also acts to accelerate the onset of time-periodic behavior. This result is attributed to coupling between the centrifugal force and the intense, buoyancy-driven flows. Proportional, proportional-integral, and input-output linearizing controllers are applied to vertical Bridgman systems in stabilizing (crystal below the melt) and destabilizing (melt below the crystal) configurations. The spatially-averaged, axisymmetric kinetic energy is the controlled output. The flows are controlled via rotation of the crucible containing the molten material. Simulation results show that feedback controllers using crucible rotation effectively attenuate flow oscillations in a stabilizing configuration with time-varying disturbance. Crucible rotation is not an optimal choice for suppressing inherent flow oscillations in the destabilizing configuration.

Wake flow control using a dynamically controlled wind turbine

NASA Astrophysics Data System (ADS)

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).

Transformative Pulsed Power Science and Technology

DTIC Science & Technology

2014-12-16

Lin, D. Singleton, J. Sanders, A. Kuthi and M.A. Gundersen, “Experimental study of pulsed corona discharge in air at high pressures”, 65th Annual...Kastner, E. Gutmark, and M. A. Gundersen. “Surface Streamer Discharge for Plasma Flow Control Using Nanosecond Pulsed Power.” Plasma Sciences, IEEE... discharge in atmospheric pressure fuel/air mixtures”, J. Phys. D: Appl. Phys. 45 495401 (2012). 28. S. J. Pendleton, S. Bowman, C. Carter, M. A. Gundersen

Persistence of baroreceptor control of cerebral blood flow velocity at a simulated altitude of 5000 m.

PubMed

Passino, Claudio; Cencetti, Simone; Spadacini, Giammario; Quintana, Robert; Parker, Daryl; Robergs, Robert; Appenzeller, Otto; Bernardi, Luciano

2007-09-01

To assess the effects of acute exposure to simulated high altitude on baroreflex control of mean cerebral blood flow velocity (MCFV). We compared beat-to-beat changes in RR interval, arterial blood pressure, mean MCFV (by transcranial Doppler velocimetry in the middle cerebral artery), end-tidal CO2, oxygen saturation and respiration in 19 healthy subjects at baseline (Albuquerque, 1779 m), after acute exposure to simulated high altitude in a hypobaric chamber (barometric pressure as at 5000 m) and during oxygen administration (to achieve 100% oxygen saturation) at the same barometric pressure (HOX). Baroreflex control on each signal was assessed by univariate and bivariate power spectral analysis performed on time series obtained during controlled (15 breaths/min) breathing, before and during baroreflex modulation induced by 0.1-Hz sinusoidal neck suction. At baseline, neck suction was able to induce a clear increase in low-frequency power in MCFV (P<0.001) as well as in RR and blood pressure. At high altitude, MCFV, as well as RR and blood pressure, was still able to respond to neck suction (all P<0.001), compared to controlled breathing alone, despite marked decreases in end-tidal CO2 and oxygen saturation at high altitude. A similar response was obtained at HOX. Phase delay analysis excluded a passive transmission of low-frequency oscillations from arterial pressure to cerebral circulation. During acute exposure to high altitude, cerebral blood flow is still modulated by the autonomic nervous system through the baroreflex, whose sensitivity is not affected by changes in CO2 and oxygen saturation levels.

Mechanisms of Active Aerodynamic Load Reduction on a Rotorcraft Fuselage With Rotor Effects

NASA Technical Reports Server (NTRS)

Schaeffler, Norman W.; Allan, Brian G.; Jenkins, Luther N.; Yao, Chung-Sheng; Bartram, Scott M.; Mace, W. Derry; Wong, Oliver D.; Tanner, Philip E.

2016-01-01

The reduction of the aerodynamic load that acts on a generic rotorcraft fuselage by the application of active flow control was investigated in a wind tunnel test conducted on an approximately 1/3-scale powered rotorcraft model simulating forward flight. The aerodynamic mechanisms that make these reductions, in both the drag and the download, possible were examined in detail through the use of the measured surface pressure distribution on the fuselage, velocity field measurements made in the wake directly behind the ramp of the fuselage and computational simulations. The fuselage tested was the ROBIN-mod7, which was equipped with a series of eight slots located on the ramp section through which flow control excitation was introduced. These slots were arranged in a U-shaped pattern located slightly downstream of the baseline separation line and parallel to it. The flow control excitation took the form of either synthetic jets, also known as zero-net-mass-flux blowing, and steady blowing. The same set of slots were used for both types of excitation. The differences between the two excitation types and between flow control excitation from different combinations of slots were examined. The flow control is shown to alter the size of the wake and its trajectory relative to the ramp and the tailboom and it is these changes to the wake that result in a reduction in the aerodynamic load.

A Theoretical Solid Oxide Fuel Cell Model for System Controls and Stability Design

NASA Technical Reports Server (NTRS)

Kopasakis, George; Brinson, Thomas; Credle, Sydni; Xu, Ming

2006-01-01

As the aviation industry moves towards higher efficiency electrical power generation, all electric aircraft, or zero emissions and more quiet aircraft, fuel cells are sought as the technology that can deliver on these high expectations. The Hybrid Solid Oxide Fuel Cell system combines the fuel cell with a microturbine to obtain up to 70 percent cycle efficiency, and then distributes the electrical power to the loads via a power distribution system. The challenge is to understand the dynamics of this complex multi-discipline system, and design distributed controls that take the system through its operating conditions in a stable and safe manner while maintaining the system performance. This particular system is a power generation and distribution system and the fuel cell and microturbine model fidelity should be compatible with the dynamics of the power distribution system in order to allow proper stability and distributed controls design. A novel modeling approach is proposed for the fuel cell that will allow the fuel cell and the power system to be integrated and designed for stability, distributed controls, and other interface specifications. This investigation shows that for the fuel cell, the voltage characteristic should be modeled, but in addition, conservation equation dynamics, ion diffusion, charge transfer kinetics, and the electron flow inherent impedance should also be included.

Mobility power flow analysis of an L-shaped plate structure subjected to acoustic excitation

NASA Technical Reports Server (NTRS)

Cuschieri, J. M.

1989-01-01

An analytical investigation based on the Mobility Power Flow method is presented for the determination of the vibrational response and power flow for two coupled flat plate structures in an L-shaped configuration, subjected to acoustical excitation. The principle of the mobility power flow method consists of dividing the global structure into a series of subsystems coupled together using mobility functions. Each separate subsystem is analyzed independently to determine the structural mobility functions for the junction and excitation locations. The mobility functions, together with the characteristics of the junction between the subsystems, are then used to determine the response of the global structure and the power flow. In the coupled plate structure considered here, mobility power flow expressions are derived for excitation by an incident acoustic plane wave. In this case, the forces (acoustic pressures) acting on the structure are dependent on the response of the structure because of the scattered pressure component. The interaction between the structure and the fluid leads to the derivation of a corrected mode shape for the plates' normal surface velocity and also for the structure mobility functions. The determination of the scattered pressure components in the expressions for the power flow represents an additional component in the power flow balance for the source plate and the receiver plate. This component represents the radiated acoustical power from the plate structure.

Integration Tests of the 4 kW-class High Voltage Hall Accelerator Power Processing Unit with the HiVHAc and the SPT-140 Hall Effect Thrusters

NASA Technical Reports Server (NTRS)

Kamhawi, Hani; Pinero, Luis; Haag, Thomas; Huang, Wensheng; Ahern, Drew; Liang, Ray; Shilo, Vlad

2016-01-01

NASAs Science Mission Directorate is sponsoring the development of a 4 kW-class Hall propulsion system for implementation in NASA science and exploration missions. The main components of the system include the High Voltage Hall Accelerator (HiVHAc), an engineering model power processing unit (PPU) developed by Colorado Power Electronics, and a xenon flow control module (XFCM) developed by VACCO Industries. NASA Glenn Research Center is performing integrated tests of the Hall thruster propulsion system. This presentation presents results from integrated tests of the PPU and XFCM with the HiVHAc engineering development thruster and a SPT-140 thruster provided by Space System Loral. The results presented in this paper demonstrate thruster discharge initiation, open-loop and closed-loop control of the discharge current with anode flow for both the HiVHAc and the SPT-140 thrusters. Integrated tests with the SPT-140 thruster indicated that the PPU was able to repeatedly initiate the thrusters discharge, achieve steady state operation, and successfully throttle the thruster between 1.5 and 4.5 kW. The measured SPT-140 performance was identical to levels reported by Space Systems Loral.

FACTS Devices Cost Recovery During Congestion Management in Deregulated Electricity Markets

NASA Astrophysics Data System (ADS)

Sharma, Ashwani Kumar; Mittapalli, Ram Kumar; Pal, Yash

2016-09-01

In future electricity markets, flexible alternating current transmission system (FACTS) devices will play key role for providing ancillary services. Since huge cost is involved for the FACTS devices placement in the power system, the cost invested has to be recovered in their life time for the replacement of these devices. The FACTS devices in future electricity markets can act as an ancillary services provider and have to be remunerated. The main contributions of the paper are: (1) investment recovery of FACTS devices during congestion management such as static VAR compensator and unified power flow controller along with thyristor controlled series compensator using non-linear bid curves, (2) the impact of ZIP load model on the FACTS cost recovery of the devices, (3) the comparison of results obtained without ZIP load model for both pool and hybrid market model, (4) secure bilateral transactions incorporation in hybrid market model. An optimal power flow based approach has been developed for maximizing social welfare including FACTS devices cost. The optimal placement of the FACTS devices have been obtained based on maximum social welfare. The results have been obtained for both pool and hybrid electricity market for IEEE 24-bus RTS.

Development of a Cross-Flow Fan Powered Quad-Rotor Unmanned Aerial Vehicle

DTIC Science & Technology

2015-06-01

HVAC Heating ventilation and air conditioning LiPo Lithium - ion polymer PLA Polylactic acid, 3-D printer filament PVA Polyvinyl alcohol PREPREG...control console Figure 79. Rheostat speed control console. 74 c) 6 cell lithium polymer battery Figure 80. 6 Cell LiPo battery . 75 d...Radio control system and versatile unit mounted with zip ties. ......................67  Figure 75.  LiPo batteries and parallel battery connector

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dall'Anese, Emiliano; Baker, Kyri; Summers, Tyler

The paper focuses on distribution systems featuring renewable energy sources and energy storage devices, and develops an optimal power flow (OPF) approach to optimize the system operation in spite of forecasting errors. The proposed method builds on a chance-constrained multi-period AC OPF formulation, where probabilistic constraints are utilized to enforce voltage regulation with a prescribed probability. To enable a computationally affordable solution approach, a convex reformulation of the OPF task is obtained by resorting to i) pertinent linear approximations of the power flow equations, and ii) convex approximations of the chance constraints. Particularly, the approximate chance constraints provide conservative boundsmore » that hold for arbitrary distributions of the forecasting errors. An adaptive optimization strategy is then obtained by embedding the proposed OPF task into a model predictive control framework.« less

Stochastic control of smart home energy management with plug-in electric vehicle battery energy storage and photovoltaic array

NASA Astrophysics Data System (ADS)

Wu, Xiaohua; Hu, Xiaosong; Moura, Scott; Yin, Xiaofeng; Pickert, Volker

2016-11-01

Energy management strategies are instrumental in the performance and economy of smart homes integrating renewable energy and energy storage. This article focuses on stochastic energy management of a smart home with PEV (plug-in electric vehicle) energy storage and photovoltaic (PV) array. It is motivated by the challenges associated with sustainable energy supplies and the local energy storage opportunity provided by vehicle electrification. This paper seeks to minimize a consumer's energy charges under a time-of-use tariff, while satisfying home power demand and PEV charging requirements, and accommodating the variability of solar power. First, the random-variable models are developed, including Markov Chain model of PEV mobility, as well as predictive models of home power demand and PV power supply. Second, a stochastic optimal control problem is mathematically formulated for managing the power flow among energy sources in the smart home. Finally, based on time-varying electricity price, we systematically examine the performance of the proposed control strategy. As a result, the electric cost is 493.6% less for a Tesla Model S with optimal stochastic dynamic programming (SDP) control relative to the no optimal control case, and it is by 175.89% for a Nissan Leaf.

Central receiver solar thermal power system, Phase 1. CDRL item 2. Pilot plant preliminary design report. Volume VI. Electrical power generation and master control subsystems and balance of plant

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hallet, Jr., R. W.; Gervais, R. L.

1977-10-01

The requirements, performance, and subsystem configuration for both the Commercial and Pilot Plant electrical power generation subsystems (EPGS) and balance of plants are presented. The EPGS for both the Commercial Plant and Pilot Plant make use of conventional, proven equipment consistent with good power plant design practices in order to minimize risk and maximize reliability. The basic EPGS cycle selected is a regenerative cycle that uses a single automatic admission, condensing, tandem-compound double-flow turbine. Specifications, performance data, drawings, and schematics are included. (WHK)

Digital computer study of nuclear reactor thermal transients during startup of 60-kWe Brayton power conversion system

NASA Technical Reports Server (NTRS)

Jefferies, K. S.; Tew, R. C.

1974-01-01

A digital computer study was made of reactor thermal transients during startup of the Brayton power conversion loop of a 60-kWe reactor Brayton power system. A startup procedure requiring the least Brayton system complication was tried first; this procedure caused violations of design limits on key reactor variables. Several modifications of this procedure were then found which caused no design limit violations. These modifications involved: (1) using a slower rate of increase in gas flow; (2) increasing the initial reactor power level to make the reactor respond faster; and (3) appropriate reactor control drum manipulation during the startup transient.

Noninvasive assessment of vascular function and hydraulic power and efficiency in pediatric Fontan patients.

PubMed

Myers, Kimberley A; Leung, Mande T; Terri Potts, M; Potts, James E; Sandor, George G S

2013-10-01

Invasive studies have shown that children with Fontan palliation have abnormal arterial stiffness, impedance, and hydraulic power and efficiency. The aim of this study was to assess these indexes noninvasively in a cohort of children with Fontan circulation using Doppler echocardiography and compare their results with those of healthy peers. This was a case-control study of 22 Fontan patients and 31 healthy control children. Using standard two-dimensional, M-mode, and Doppler echocardiographic imaging and carotid artery applanation tonometry, aortic flows, dimensions, and pulse-wave velocity were measured, and vascular impedance and arterial stiffness were calculated. Hydraulic power and efficiency were calculated from standard fluid dynamics formulae. The median age was similar between groups. Stroke volume index (39 vs 39 mL/min/m(2)) and cardiac index (2.6 vs 2.5 L/min/m(2)) were similar. Aortic cross-sectional area (3.3 vs 2.8 cm(2)), peak aortic flow (302 vs 261 cm(3)/sec), and myocardial performance index (0.47 vs 0.25) were higher and ejection fraction (50% vs 66%) was lower in Fontan patients. Input impedance (61 vs 83 dyne · sec/cm(5)/m(2)) was lower in Fontan patients. Pulse-wave velocity (488 vs 364 cm/sec), elastic pressure-strain modulus (305 vs 263 torr), and stiffness index (4.15 vs 3.04) were higher in Fontan patients. Total arterial compliance (1.29 vs 1.32 mL/torr/m(2)) and mean power (606 vs 527 mW/m(2)) were similar and total hydraulic power (716 vs 627 mW/m(2)) was higher in Fontan patients. Efficiency and the power cost per unit of forward flow were similar. Despite stiffer aortas, Fontan patients generate more hydraulic power associated with decreased ventricular function to achieve a similar hydraulic efficiency. In Fontan patients, therapy that is given to improve ventricular function may need to target vascular stiffness as well. This technique may be used to monitor the efficacy of therapeutic interventions. Copyright © 2013 American Society of Echocardiography. Published by Mosby, Inc. All rights reserved.

Fault ride-through enhancement using an enhanced field oriented control technique for converters of grid connected DFIG and STATCOM for different types of faults.

PubMed

Ananth, D V N; Nagesh Kumar, G V

2016-05-01

With increase in electric power demand, transmission lines were forced to operate close to its full load and due to the drastic change in weather conditions, thermal limit is increasing and the system is operating with less security margin. To meet the increased power demand, a doubly fed induction generator (DFIG) based wind generation system is a better alternative. For improving power flow capability and increasing security STATCOM can be adopted. As per modern grid rules, DFIG needs to operate without losing synchronism called low voltage ride through (LVRT) during severe grid faults. Hence, an enhanced field oriented control technique (EFOC) was adopted in Rotor Side Converter of DFIG converter to improve power flow transfer and to improve dynamic and transient stability. A STATCOM is coordinated to the system for obtaining much better stability and enhanced operation during grid fault. For the EFOC technique, rotor flux reference changes its value from synchronous speed to zero during fault for injecting current at the rotor slip frequency. In this process DC-Offset component of flux is controlled, decomposition during symmetric and asymmetric faults. The offset decomposition of flux will be oscillatory in a conventional field oriented control, whereas in EFOC it was aimed to damp quickly. This paper mitigates voltage and limits surge currents to enhance the operation of DFIG during symmetrical and asymmetrical faults. The system performance with different types of faults like single line to ground, double line to ground and triple line to ground was applied and compared without and with a STATCOM occurring at the point of common coupling with fault resistance of a very small value at 0.001Ω. Copyright © 2015 ISA. Published by Elsevier Ltd. All rights reserved.

Design of an FPGA-based electronic flow regulator (EFR) for spacecraft propulsion system

NASA Astrophysics Data System (ADS)

Manikandan, J.; Jayaraman, M.; Jayachandran, M.

2011-02-01

This paper describes a scheme for electronically regulating the flow of propellant to the thruster from a high-pressure storage tank used in spacecraft application. Precise flow delivery of propellant to thrusters ensures propulsion system operation at best efficiency by maximizing the propellant and power utilization for the mission. The proposed field programmable gate array (FPGA) based electronic flow regulator (EFR) is used to ensure precise flow of propellant to the thrusters from a high-pressure storage tank used in spacecraft application. This paper presents hardware and software design of electronic flow regulator and implementation of the regulation logic onto an FPGA.Motivation for proposed FPGA-based electronic flow regulation is on the disadvantages of conventional approach of using analog circuits. Digital flow regulation overcomes the analog equivalent as digital circuits are highly flexible, are not much affected due to noise, accurate performance is repeatable, interface is easier to computers, storing facilities are possible and finally failure rate of digital circuits is less. FPGA has certain advantages over ASIC and microprocessor/micro-controller that motivated us to opt for FPGA-based electronic flow regulator. Also the control algorithm being software, it is well modifiable without changing the hardware. This scheme is simple enough to adopt for a wide range of applications, where the flow is to be regulated for efficient operation.The proposed scheme is based on a space-qualified re-configurable field programmable gate arrays (FPGA) and hybrid micro circuit (HMC). A graphical user interface (GUI) based application software is also developed for debugging, monitoring and controlling the electronic flow regulator from PC COM port.

In-situ Condition Monitoring of Components in Small Modular Reactors Using Process and Electrical Signature Analysis. Final report, volume 1. Development of experimental flow control loop, data analysis and plant monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Upadhyaya, Belle; Hines, J. Wesley; Damiano, Brian

The research and development under this project was focused on the following three major objectives: Objective 1: Identification of critical in-vessel SMR components for remote monitoring and development of their low-order dynamic models, along with a simulation model of an integral pressurized water reactor (iPWR). Objective 2: Development of an experimental flow control loop with motor-driven valves and pumps, incorporating data acquisition and on-line monitoring interface. Objective 3: Development of stationary and transient signal processing methods for electrical signatures, machinery vibration, and for characterizing process variables for equipment monitoring. This objective includes the development of a data analysis toolbox. Themore » following is a summary of the technical accomplishments under this project: - A detailed literature review of various SMR types and electrical signature analysis of motor-driven systems was completed. A bibliography of literature is provided at the end of this report. Assistance was provided by ORNL in identifying some key references. - A review of literature on pump-motor modeling and digital signal processing methods was performed. - An existing flow control loop was upgraded with new instrumentation, data acquisition hardware and software. The upgrading of the experimental loop included the installation of a new submersible pump driven by a three-phase induction motor. All the sensors were calibrated before full-scale experimental runs were performed. - MATLAB-Simulink model of a three-phase induction motor and pump system was completed. The model was used to simulate normal operation and fault conditions in the motor-pump system, and to identify changes in the electrical signatures. - A simulation model of an integral PWR (iPWR) was updated and the MATLAB-Simulink model was validated for known transients. The pump-motor model was interfaced with the iPWR model for testing the impact of primary flow perturbations (upsets) on plant parameters and the pump electrical signatures. Additionally, the reactor simulation is being used to generate normal operation data and data with instrumentation faults and process anomalies. A frequency controller was interfaced with the motor power supply in order to vary the electrical supply frequency. The experimental flow control loop was used to generate operational data under varying motor performance characteristics. Coolant leakage events were simulated by varying the bypass loop flow rate. The accuracy of motor power calculation was improved by incorporating the power factor, computed from motor current and voltage in each phase of the induction motor.- A variety of experimental runs were made for steady-state and transient pump operating conditions. Process, vibration, and electrical signatures were measured using a submersible pump with variable supply frequency. High correlation was seen between motor current and pump discharge pressure signal; similar high correlation was exhibited between pump motor power and flow rate. Wide-band analysis indicated high coherence (in the frequency domain) between motor current and vibration signals. - Wide-band operational data from a PWR were acquired from AMS Corporation and used to develop time-series models, and to estimate signal spectrum and sensor time constant. All the data were from different pressure transmitters in the system, including primary and secondary loops. These signals were pre-processed using the wavelet transform for filtering both low-frequency and high-frequency bands. This technique of signal pre-processing provides minimum distortion of the data, and results in a more optimal estimation of time constants of plant sensors using time-series modeling techniques.« less

Evaluation of exhaled nitric oxide in schoolchildren at different exhalation flow rates.

PubMed

Pedroletti, Christophe; Zetterquist, Wilhelm; Nordvall, Lennart; Alving, Kjell

2002-09-01

Nitric oxide (NO) in exhaled air is believed to reflect allergic inflammation in the airways. Measured levels of exhaled NO vary with the exhaled flow rate, which therefore must be standardized. The aim of this study was to estimate the optimal exhalation flow rate when measuring NO in exhaled air. We studied 15 asthmatic children (8-18 y) with elevated NO levels and 15 age-matched controls and focused on how the quality of the NO curve profile, the discriminatory power, and the reproducibility were influenced by the exhalation flow rate. We used an on-line system for NO measurements at six different exhalation flow rates in the interval of 11-382 mL/s. The fraction of exhaled nitric oxide (FENO) was highly flow-dependent as was expected. Intermediate flow rates yielded a flat and stable NO plateau and were considerably easier to interpret than those obtained at the highest and lowest flow rates. The ratio of FENO between asthmatics and controls was lower at higher flow rates and a considerable overlap in NO values was demonstrated at all flow rates except 50 mL/s. The reproducibility was much lower at more extreme flow rates and was best at 50 mL/s. We conclude that a target exhalation flow rate of approximately 50 mL/s is to be preferred using the single-breath method for on-line NO measurements in schoolchildren.

Investigation of Injector Slot Geometry on Curved-Diffuser Aerodynamic Performance

NASA Technical Reports Server (NTRS)

Silva, Odlanier

2004-01-01

The Compressor Branch vision is to be recognized as world-class leaders in research for fluid mechanics of compressors. Its mission is to conduct research and develop technology to advance the state of the art of compressors and transfer new technology to U.S. industries. Maintain partnerships with U.S. industries, universities, and other government organizations. Maintain a balance between customers focused and long range research. Flow control comprises enabling technologies to meet compression system performance requirements driven by emissions and fuel reduction goals (e.g., in UEET), missions (e.g., access-to-space), aerodynamically aggressive vehicle configurations (e.g., UAV and future blended wing body configurations with highly distorted inlets), and cost goals (e.g., in VAATE). The compression system requirements include increased efficiency, power-to-weight, and adaptability (i.e., robustness in terms of wide operability, distortion tolerance, and engine system health and reliability). The compressor flow control task comprises efforts to develop, demonstrate, and transfer adaptive flow control technology to industry to increase aerodynamic loading at current blade row loss levels, to enable adaptive1 y wide operability, and to develop plant models for adaptive compression systems. In this context, flow control is the controlled modification of a flow field by a deliberate means beyond the natural (uncontrolled) shaping of the solid surfaces that define the principal flow path. The objective of the compressor flow control task is to develop and apply techniques that control circulation, aerodynamic blockage, and entropy production in order to enhance the performance and operability of compression systems for advanced aero-propulsion applications. This summer I would be working with a curved-diffuser because it simulates what happens with flow in the stator blades in the compressor. With this experiment I will be doing some data analysis and parametric study of the injector slot geometries to get the best aerodynamic performance of it. This includes some data reduction, redesign and fast prototyping of the injector nozzle.

Charging, power management, and battery degradation mitigation in plug-in hybrid electric vehicles: A unified cost-optimal approach

NASA Astrophysics Data System (ADS)

Hu, Xiaosong; Martinez, Clara Marina; Yang, Yalian

2017-03-01

Holistic energy management of plug-in hybrid electric vehicles (PHEVs) in smart grid environment constitutes an enormous control challenge. This paper responds to this challenge by investigating the interactions among three important control tasks, i.e., charging, on-road power management, and battery degradation mitigation, in PHEVs. Three notable original contributions distinguish our work from existing endeavors. First, a new convex programming (CP)-based cost-optimal control framework is constructed to minimize the daily operational expense of a PHEV, which seamlessly integrates costs of the three tasks. Second, a straightforward but useful sensitivity assessment of the optimization outcome is executed with respect to price changes of battery and energy carriers. The potential impact of vehicle-to-grid (V2G) power flow on the PHEV economy is eventually analyzed through a multitude of comparative studies.

Modeling transport kinetics in clinoptilolite-phosphate rock systems

NASA Technical Reports Server (NTRS)

Allen, E. R.; Ming, D. W.; Hossner, L. R.; Henninger, D. L.

1995-01-01

Nutrient release in clinoptilolite-phosphate rock (Cp-PR) systems occurs through dissolution and cation-exchange reactions. Investigating the kinetics of these reactions expands our understanding of nutrient release processes. Research was conducted to model transport kinetics of nutrient release in Cp-PR systems. The objectives were to identify empirical models that best describe NH4, K, and P release and define diffusion-controlling processes. Materials included a Texas clinoptilolite (Cp) and North Carolina phosphate rock (PR). A continuous-flow thin-disk technique was used. Models evaluated included zero order, first order, second order, parabolic diffusion, simplified Elovich, Elovich, and power function. The power-function, Elovich, and parabolic-diffusion models adequately described NH4, K, and P release. The power-function model was preferred because of its simplicity. Models indicated nutrient release was diffusion controlled. Primary transport processes controlling nutrient release for the time span observed were probably the result of a combination of several interacting transport mechanisms.

Power generation systems and methods

NASA Technical Reports Server (NTRS)

Jones, Jack A. (Inventor); Chao, Yi (Inventor)

2011-01-01

A power generation system includes a plurality of submerged mechanical devices. Each device includes a pump that can be powered, in operation, by mechanical energy to output a pressurized output liquid flow in a conduit. Main output conduits are connected with the device conduits to combine pressurized output flows output from the submerged mechanical devices into a lower number of pressurized flows. These flows are delivered to a location remote of the submerged mechanical devices for power generation.

Vibration Power Flow In A Constrained Layer Damping Cylindrical Shell

NASA Astrophysics Data System (ADS)

Wang, Yun; Zheng, Gangtie

2012-07-01

In this paper, the vibration power flow in a constrained layer damping (CLD) cylindrical shell using wave propagation approach is investigated. The dynamic equations of the shell are derived with the Hamilton principle in conjunction with the Donnell shell assumption. With these equations, the dynamic responses of the system under a line circumferential cosine harmonic exciting force is obtained by employing the Fourier transform and the residue theorem. The vibration power flows inputted to the system and transmitted along the shell axial direction are both studied. The results show that input power flow varies with driving frequency and circumferential mode order, and the constrained damping layer can obviously restrict the exciting force from inputting power flow into the base shell especially for a thicker viscoelastic layer, a thicker or stiffer constraining layer (CL), and a higher circumferential mode order, can rapidly attenuate the vibration power flow transmitted along the base shell axial direction.

Mechanical energy and power flow of the upper extremity in manual wheelchair propulsion.

PubMed

Guo, Lan-Yuen; Su, Fong-Chin; Wu, Hong-Wen; An, Kai-Nan

2003-02-01

To investigate the characteristics of mechanical energy and power flow of the upper limb during wheelchair propulsion. Mechanical energy and power flow of segments were calculated. Very few studies have taken into account the mechanical energy and power flow of the musculoskeletal system during wheelchair propulsion. Mechanical energy and power flow have proven to be useful tools for investigating locomotion disorders during human gait. Twelve healthy male adults (mean age, 23.5 years) were recruited for this study. Three-dimensional kinematic and kinetic data of the upper extremity were collected during wheelchair propulsion using a Hi-Res Expert Vision system and an instrumented wheel, respectively. During the initiation of the propulsion phase, joint power is generated in the upper arm or is transferred from the trunk downward to the forearm and hand to propel the wheel forward. During terminal propulsion, joint power is transferred upward to the trunk from the forearm and upper arm. The rate of change of mechanical energy and power flow for the forearm and hand have similar patterns, but the upper arm values differ. Joint power plays an important role in energy transfer as well as the energy generated and absorbed by muscles spanning the joints during wheelchair propulsion. Energy and power flow information during wheelchair propulsion allows us to gain a better understanding of the coordination of the movement by the musculoskeletal system.

Nuclear-coupled thermal-hydraulic stability analysis of boiling water reactors

NASA Astrophysics Data System (ADS)

Karve, Atul A.

We have studied the nuclear-coupled thermal-hydraulic stability of boiling water reactors (BWRs) using a model we developed from: the space-time modal neutron kinetics equations based on spatial omega-modes, the equations for two-phase flow in parallel boiling channels, the fuel rod heat conduction equations, and a simple model for the recirculation loop. The model is represented as a dynamical system comprised of time-dependent nonlinear ordinary differential equations, and it is studied using stability analysis, modern bifurcation theory, and numerical simulations. We first determine the stability boundary (SB) in the most relevant parameter plane, the inlet-subcooling-number/external-pressure-drop plane, for a fixed control rod induced external reactivity equal to the 100% rod line value and then transform the SB to the practical power-flow map. Using this SB, we show that the normal operating point at 100% power is very stable, stability of points on the 100% rod line decreases as the flow rate is reduced, and that points are least stable in the low-flow/high-power region. We also determine the SB when the modal kinetics is replaced by simple point reactor kinetics and show that the first harmonic mode has no significant effect on the SB. Later we carry out the relevant numerical simulations where we first show that the Hopf bifurcation, that occurs as a parameter is varied across the SB is subcritical, and that, in the important low-flow/high-power region, growing oscillations can result following small finite perturbations of stable steady-states on the 100% rod line. Hence, a point on the 100% rod line in the low-flow/high-power region, although stable, may nevertheless be a point at which a BWR should not be operated. Numerical simulations are then done to calculate the decay ratios (DRs) and frequencies of oscillations for various points on the 100% rod line. It is determined that the NRC requirement of DR < 0.75-0.8 is not rigorously satisfied in the low-flow/high-power region and hence these points should be avoided during normal startup and shutdown operations. The frequency of oscillation is shown to decrease as the flow rate is reduced and the frequency of 0.5Hz observed in the low-flow/high-power region is consistent with those observed during actual instability incidents. Additional numerical simulations show that in the low-flow/high-power region, for the same initial conditions, the use of point kinetics leads to damped oscillations, whereas the model that includes the modal kinetics equations results in growing nonlinear oscillations. Thus, we show that side-by-side out-of-phase growing power oscillations result due to the very important first harmonic mode effect and that the use of point kinetics, which fails to predict these growing oscillations, leads to dramatically nonconservative results. Finally, the effect of a simple recirculation loop model that we develop is studied by carrying out additional stability analyses and additional numerical simulations. It is shown that the loop has a stabilizing effect on certain points on the 100% rod line for time delays equal to integer multiples of the natural period of oscillation, whereas it has a destabilizing effect for half-integer multiples. However, for more practical time delays, it is determined that the overall effect generally is destabilizing.

System for detecting and limiting electrical ground faults within electrical devices

DOEpatents

Gaubatz, Donald C.

1990-01-01

An electrical ground fault detection and limitation system for employment with a nuclear reactor utilizing a liquid metal coolant. Elongate electromagnetic pumps submerged within the liquid metal coolant and electrical support equipment experiencing an insulation breakdown occasion the development of electrical ground fault current. Without some form of detection and control, these currents may build to damaging power levels to expose the pump drive components to liquid metal coolant such as sodium with resultant undesirable secondary effects. Such electrical ground fault currents are detected and controlled through the employment of an isolated power input to the pumps and with the use of a ground fault control conductor providing a direct return path from the affected components to the power source. By incorporating a resistance arrangement with the ground fault control conductor, the amount of fault current permitted to flow may be regulated to the extent that the reactor may remain in operation until maintenance may be performed, notwithstanding the existence of the fault. Monitors such as synchronous demodulators may be employed to identify and evaluate fault currents for each phase of a polyphase power, and control input to the submerged pump and associated support equipment.

Control system and method for a universal power conditioning system

DOEpatents

Lai, Jih-Sheng; Park, Sung Yeul; Chen, Chien-Liang

2014-09-02

A new current loop control system method is proposed for a single-phase grid-tie power conditioning system that can be used under a standalone or a grid-tie mode. This type of inverter utilizes an inductor-capacitor-inductor (LCL) filter as the interface in between inverter and the utility grid. The first set of inductor-capacitor (LC) can be used in the standalone mode, and the complete LCL can be used for the grid-tie mode. A new admittance compensation technique is proposed for the controller design to avoid low stability margin while maintaining sufficient gain at the fundamental frequency. The proposed current loop controller system and admittance compensation technique have been simulated and tested. Simulation results indicate that without the admittance path compensation, the current loop controller output duty cycle is largely offset by an undesired admittance path. At the initial simulation cycle, the power flow may be erratically fed back to the inverter causing catastrophic failure. With admittance path compensation, the output power shows a steady-state offset that matches the design value. Experimental results show that the inverter is capable of both a standalone and a grid-tie connection mode using the LCL filter configuration.

Status of linear boundary-layer stability and the e to the nth method, with emphasis on swept-wing applications

NASA Technical Reports Server (NTRS)

Hefner, J. N.; Bushnell, D. M.

1980-01-01

The-state-of-the-art for the application of linear stability theory and the e to the nth power method for transition prediction and laminar flow control design are summarized, with analyses of previously published low disturbance, swept wing data presented. For any set of transition data with similar stream distrubance levels and spectra, the e to the nth power method for estimating the beginning of transition works reasonably well; however, the value of n can vary significantly, depending upon variations in disturbance field or receptivity. Where disturbance levels are high, the values of n are appreciably below the usual average value of 9 to 10 obtained for relatively low disturbance levels. It is recommended that the design of laminar flow control systems be based on conservative estimates of n and that, in considering the values of n obtained from different analytical approaches or investigations, the designer explore the various assumptions which entered into the analyses.

Sensor for Individual Burner Control of Coal Firing Rate, Fuel-Air Ratio and Coal Fineness Correlation

DOE Office of Scientific and Technical Information (OSTI.GOV)

R. Demler

2006-04-01

Accurate, cost-efficient monitoring instrumentation has long been considered essential to the operation of power plants. Nonetheless, for the monitoring of coal flow, such instrumentation has been sorely lacking and technically difficult to achieve. With more than half of the electrical power in the United States currently supplied by coal, energy generated by this resource is critical to the US economy. The demand for improvement in this area has only increased as a result of the following two situations: First, deregulation has produced a heightened demand for both reduced electrical cost and improved grid connectivity. Second, environmental concerns have simultaneously resultedmore » in a need for both increased efficiency and reduced carbon and NOx emissions. A potential approach to addressing both these needs would be improvement in the area of combustion control. This would result in a better heat rate, reduced unburned carbon in ash, and reduced NOx emissions. However, before feedback control can be implemented, the ability to monitor coal flow to the burners in real-time must be established. While there are several ''commercially available'' products for real-time coal flow measurement, power plant personnel are highly skeptical about the accuracy and longevity of these systems in their current state of development. In fact, following several demonstration projects of in-situ coal flow measurement systems in full scale utility boilers, it became obvious that there were still many unknown influences on these instruments during field applications. Due to the operational environment of the power plant, it has been difficult if not impossible to sort out what parameters could be influencing the various probe technologies. Additionally, it has been recognized for some time that little is known regarding the performance of coal flow splitters, even where rifflers are employed. Often the coal flow distribution from these splitters remains mal-distributed. There have been mixed results in the field using variable orifices in coal pipes. Development of other coal flow control devices has been limited. An underlying difficulty that, to date, has hindered the development of an accurate instrument for coal flow measurements is the fact that coal flow is characterized by irregular temporal and spatial variation. However, despite the inherent complexity of the dynamic system, the system is in fact deterministic. Therefore, in principle, the coal flow can be deduced from the dynamics it exhibits. Nonetheless, the interactions are highly nonlinear, rendering standard signal processing approaches, which rely on techniques such as frequency decomposition, to be of little value. Foster-Miller, Inc. has developed a methodology that relates the complex variation in such systems to the information of interest. This technology will be described in detail in Section 2. A second concern regarding the current measurement systems is installation, which can be labor-intensive and cost-prohibitive. A process that does not require the pulverizer to be taken off line would be highly desirable. Most microwave and electrostatic methods require drilling up to 20 holes in the pipe, all with a high degree of precision so as to produce a proper alignment of the probes. At least one electrostatic method requires a special spool piece to be fitted into each existing coal pipe. Overall, these procedures are both difficult and very expensive. An alternative approach is pursued here, namely the development of an instrument that relies on an acoustic signal captured by way of a commercial accelerometer. The installation of this type of sensor is both simpler and less invasive than other techniques. An accelerometer installed in a pipe wall need not penetrate through the wall, which means that the system may be able to remain on line during the installation. Further, due to the fact that the Dynamical Instruments technology, unlike other systems, does not rely on uniformity of the air or coal profile, the installation location need not be on a long, straight run of pipe. In fact, an optimal signal is obtained near a pipe elbow. This is fortuitous, as bends are often more accessible on pipes in a power plant than straight sections. In contrast to measurement systems that rely on the uniformity of the air and coal profile, the accuracy of the system under development will not compromised by varying levels of flow uniformity.« less

Automotive Stirling Engine Mod 1 Design Review, volume 2

NASA Technical Reports Server (NTRS)

1982-01-01

The auxiliaries and the control system for the ASE MOD I: (1) provide the required fuel and air flows for a well controlled combustion process, generating heat to the Stirling cycle; (2) provide a driver acceptable method for controlling the power output of the engine; (3) provide adequate lubrication and cooling water circulation; (4) generate the electric energy required for engine and vehicle operation; (5) provide a driver acceptable method for starting, stopping and monitoring the engine; and (6) provide a guard system, that protects the engine at component or system malfunction. The control principles and the way the different components and sub-systems interact are described as well as the different auxiliaries, the air fuel system, the power control systems and the electronics. The arrangement and location of auxiliaries and other major components are also examined.

Bosch CO2 Reduction System Development

NASA Technical Reports Server (NTRS)

Holmes, R. F.; King, C. D.; Keller, E. E.

1975-01-01

Refinements in the design of a Bosch CO2 reduction unit for spacecraft O2 production are described. Sealing of the vacuum insulation jacket was simplified so that high vacuum and high insulation performance are easily maintained. The device includes a relatively simple concentric shell recuperative heat exchanger which operates at approximately 95% temperature effectiveness and helps lower power consumption. The influence of reactor temperature, pressure, and recycle gas composition on power consumption was investigated. In general, precise control is not required since power consumption is not very sensitive to moderate variations of these parameters near their optimum values. There are two process rate control modes which match flow rate to process demand. Catalyst conditioning, support, and packing pattern developments assure consistent starts, reduced energy consumption, and extended cartridge life. Operation levels for four or five men were maintained with overall power input values of 50 to 60 watts per man.

Evaluation of the effect of reactant gases mass flow rates on power density in a polymer electrolyte membrane fuel cell

NASA Astrophysics Data System (ADS)

Kahveci, E. E.; Taymaz, I.

2018-03-01

In this study it was experimentally investigated the effect of mass flow rates of reactant gases which is one of the most important operational parameters of polymer electrolyte membrane (PEM) fuel cell on power density. The channel type is serpentine and single PEM fuel cell has an active area of 25 cm2. Design-Expert 8.0 (trial version) was used with four variables to investigate the effect of variables on the response using. Cell temperature, hydrogen mass flow rate, oxygen mass flow rate and humidification temperature were selected as independent variables. In addition, the power density was used as response to determine the combined effects of these variables. It was kept constant cell and humidification temperatures while changing mass flow rates of reactant gases. From the results an increase occurred in power density with increasing the hydrogen flow rates. But oxygen flow rate does not have a significant effect on power density within determined mass flow rates.

Development of 3 and 5kW Fuel Cell Power Plants

DTIC Science & Technology

1985-12-12

automotive type air -cooled (cross-flow) copper heat exchanger (Figure 7.7) was used for water reclamation. A 48V, 0.5A brushless DC blower was used to...and the balance is combusted in ’a burner to supply heat required for the endothermic reforming process. The phosphoric acid fuel cell stack is air ...the use of inter- changeable power conditioners . A microprocessor based con- troller provides event sequencing and system. control during startup

Zinc Bromide Flow Battery Installation for Islanding and Backup Power

DTIC Science & Technology

2017-08-09

predictably is in place. The ability to control generation has become more difficult with the increase of RE systems such as solar PV and wind turbines ...Both PV and wind systems generate power based on unpredictable cycles of nature. At very low levels of RE penetration the grid can be balanced by...Page Intentionally Left Blank 15 5.0 TEST DESIGN This goal of this demonstration was to solve two main problems . The first

Room temperature micro-hydrogen-generator

NASA Astrophysics Data System (ADS)

Gervasio, Don; Tasic, Sonja; Zenhausern, Frederic

A new compact and cost-effective hydrogen-gas generator has been made that is well suited for supplying hydrogen to a fuel-cell for providing base electrical power to hand-carried appliances. This hydrogen-generator operates at room temperature, ambient pressure and is orientation-independent. The hydrogen-gas is generated by the heterogeneous catalytic hydrolysis of aqueous alkaline borohydride solution as it flows into a micro-reactor. This reactor has a membrane as one wall. Using the membrane keeps the liquid in the reactor, but allows the hydrogen-gas to pass out of the reactor to a fuel-cell anode. Aqueous alkaline 30 wt% borohydride solution is safe and promotes long application life, because this solution is non-toxic, non-flammable, and is a high energy-density (≥2200 W-h per liter or per kilogram) hydrogen-storage solution. The hydrogen is released from this storage-solution only when it passes over the solid catalyst surface in the reactor, so controlling the flow of the solution over the catalyst controls the rate of hydrogen-gas generation. This allows hydrogen generation to be matched to hydrogen consumption in the fuel-cell, so there is virtually no free hydrogen-gas during power generation. A hydrogen-generator scaled for a system to provide about 10 W electrical power is described here. However, the technology is expected to be scalable for systems providing power spanning from 1 W to kW levels.

Evaluation of joint effusion in rabbits by color Doppler, power Doppler, and contrast-enhanced power Doppler ultrasonography.

PubMed

Lim, Gye-Yeon; Im, Soo Ah; Jung, Won Sang; Lee, Jae Mun; Lee, Ah Won

2005-09-01

The aim of this prospective study was to evaluate the diagnostic value of power Doppler ultrasonography (PDUS) and contrast-enhanced PDUS (CEPDUS) in the depiction and characterization of experimentally induced arthritis in the rabbit. Thirty rabbits were divided into three groups consisting of one control group (saline injection group) and two experimental groups: a suppurative arthritis group and a chemically induced synovitis group. The same amount (1 ml) of each agent was directly injected into the right hip joint. Serial color Doppler ultrasound (CDUS), PDUS, and CEPDUS images were obtained before and after injection. We observed that all of the infected knees in the suppurative arthritis group with Staphylococcus aureus demonstrated an increased signal on PDUS after inoculation. A minimal power Doppler signal was presented in the chemically induced synovitis group with talc injection, but none of the control knees demonstrated any increased signals. CEPDUS was the most sensitive imaging modality for evaluating the increase of blood flows in suppurative arthritis and was subsequently followed by PDUS and CDUS. The increased signals obtained with PDUS represent increased local blood flows; therefore, this technique can be used for evaluating the degree of inflammation. Furthermore, using the contrast agent enhances the sensitivity of PDUS, and it can even be useful for differentiating borderline cases. Copyright 2005 Wiley Periodicals, Inc

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jager, Yetta; Smith, Brennan T

Hydroelectric power provides a cheap source of electricity with few carbon emissions. Yet, reservoirs are not operated sustainably, which we define as meeting societal needs for water and power while protecting long-term health of the river ecosystem. Reservoirs that generate hydropower are typically operated with the goal of maximizing energy revenue, while meeting other legal water requirements. Reservoir optimization schemes used in practice do not seek flow regimes that maximize aquatic ecosystem health. Here, we review optimization studies that considered environmental goals in one of three approaches. The first approach seeks flow regimes that maximize hydropower generations while satisfying legalmore » requirements, including environmental (or minimum) flows. Solutions from this approach are often used in practice to operate hydropower projects. In the second approach, flow releases from a dam are timed to meet water quality constraints on dissolved oxygen (DO), temperature and nutrients. In the third approach, flow releases are timed to improve the health of fish populations. We conclude by suggesting three steps for bringing multi-objective reservoir operation closer to the goal of ecological sustainability: (1) conduct research to identify which features of flow variation are essential for river health and to quantify these relationships, (2) develop valuation methods to assess the total value of river health and (3) develop optimal control softwares that combine water balance modeling with models that predict ecosystem responses to flow.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jager, Yetta; Smith, Brennan T

Hydroelectric power provides a cheap source of electricity with few carbon emissions. Yet, reservoirs are not operated sustainably, which we define as meeting societal needs for water and power while protecting long-term health of the river ecosystem. Reservoirs that generate hydropower are typically operated with the goal of maximizing energy revenue, while meeting other legal water requirements. Reservoir optimization schemes used in practice do not seek flow regimes that maximize aquatic ecosystem health. Here, we review optimization studies that considered environmental goals in one of three approaches. The first approach seeks flow regimes that maximize hydropower generation, while satisfying legalmore » requirements, including environmental (or minimum) flows. Solutions from this approach are often used in practice to operate hydropower projects. In the second approach, flow releases from a dam are timed to meet water quality constraints on dissolved oxygen (DO), temperature and nutrients. In the third approach, flow releases are timed to improve the health of fish populations. We conclude by suggesting three steps for bringing multi-objective reservoir operation closer to the goal of ecological sustainability: (1) conduct research to identify which features of flow variation are essential for river health and to quantify these relationships, (2) develop valuation methods to assess the total value of river health and (3) develop optimal control softwares that combine water balance modelling with models that predict ecosystem responses to flow.« less

Generation and reactions of oxiranyllithiums by use of a flow microreactor system.

PubMed

Nagaki, Aiichiro; Takizawa, Eiji; Yoshida, Jun-ichi

2010-12-17

A flow microreactor system consisting of micromixers and microtubes provides an effective reactor for the generation and reactions of aryloxiranyllithiums without decomposition by virtue of short residence time and efficient temperature control. The deprotonation of styrene oxides with sBuLi can be conducted by using the flow microreactor system at -78 or -68 °C (whereas much lower temperatures (< -100 °C) are needed for the same reactions conducted under macrobatch conditions). The resulting α-aryloxiranyllithiums were allowed to react with electrophiles in the flow microreactor system at the same temperature. The sequential introduction of various electrophiles onto 2,3-diphenyloxiranes was also achieved by using an integrated flow microreactor, which serves as a powerful system for the stereoselective synthesis of tetrasubstituted epoxides.

In vitro evaluation of forward and reverse volumetric flow across a regurgitant aortic valve using Doppler power-weighted mean velocities.

PubMed

Minich, L L; Tani, L Y; Pantalos, G M

1997-01-01

To determine the accuracy of using power-weighted mean velocities for quantitating volumetric flow across a cardiac valve, we equipped pulsatile flow-tank systems with a 25 mm porcine or a 27 mm mechanical valve with various sizes of regurgitant orifices. Forward and reverse volumetric flows were measured over a range of hemodynamic conditions using two insonating angles (0 and 45 degrees). Pulsed Doppler power-weighted mean velocity measurements were obtained simultaneously with electromagnetic or ultrasonic transit-time probe measurements. For the porcine valve, Doppler measurements correlated well with electromagnetic flow measurements for all (r = 0.75 to 0.97, p < 0.05) except the smallest (2.7 mm) orifice (r = 0.19). For the mechanical valve, power-weighted mean velocity measurements correlated well with ultrasonic transit-time measurements for each hemodynamic condition defined by pulse rate, mean arterial pressure, and insonating angle (r = 0.93 to 0.99, p < 0.01), but equations varied unpredictably. Thus, although power-weighted mean velocity volumetric flow measurements correlate well with flow probe measurements, equations vary widely as hemodynamic conditions change. Because of this variation, power-weighted mean velocity data are not useful for quantitation of volumetric flow across a cardiac valve at this time. Further investigation may show how different hemodynamic conditions affect power-weighted mean velocity measurements of volumetric flow.

A novel optimized hybrid fuzzy logic intelligent PID controller for an interconnected multi-area power system with physical constraints and boiler dynamics.

PubMed

Gomaa Haroun, A H; Li, Yin-Ya

2017-11-01

In the fast developing world nowadays, load frequency control (LFC) is considered to be a most significant role for providing the power supply with good quality in the power system. To deliver a reliable power, LFC system requires highly competent and intelligent control technique. Hence, in this article, a novel hybrid fuzzy logic intelligent proportional-integral-derivative (FLiPID) controller has been proposed for LFC of interconnected multi-area power systems. A four-area interconnected thermal power system incorporated with physical constraints and boiler dynamics is considered and the adjustable parameters of the FLiPID controller are optimized using particle swarm optimization (PSO) scheme employing an integral square error (ISE) criterion. The proposed method has been established to enhance the power system performances as well as to reduce the oscillations of uncertainties due to variations in the system parameters and load perturbations. The supremacy of the suggested method is demonstrated by comparing the simulation results with some recently reported heuristic methods such as fuzzy logic proportional-integral (FLPI) and intelligent proportional-integral-derivative (PID) controllers for the same electrical power system. the investigations showed that the FLiPID controller provides a better dynamic performance and outperform compared to the other approaches in terms of the settling time, and minimum undershoots of the frequency as well as tie-line power flow deviations following a perturbation, in addition to perform appropriate settlement of integral absolute error (IAE). Finally, the sensitivity analysis of the plant is inspected by varying the system parameters and operating load conditions from their nominal values. It is observed that the suggested controller based optimization algorithm is robust and perform satisfactorily with the variations in operating load condition, system parameters and load pattern. Copyright © 2017 ISA. Published by Elsevier Ltd. All rights reserved.

Application of Microsecond Voltage Pulses for Water Disinfection by Diaphragm Electric Discharge

NASA Astrophysics Data System (ADS)

Kakaurov, S. V.; Suvorov, I. F.; Yudin, A. S.; Solovyova, T. L.; Kuznetsova, N. S.

2015-11-01

The paper presents the dependence of copper and silver ions formation on the duration of voltage pulses of diaphragm electric discharge and on the pH of treated liquid medium. Knowing it allows one to create an automatic control system to control bactericidal agent's parameters obtained in diaphragm electric discharge reactor. The current-voltage characteristic of the reactor with a horizontal to the diaphragm membrane water flow powered from the author's custom pulse voltage source is also presented. The results of studies of the power consumption of diaphragm electric discharge depending on temperature of the treated liquid medium are given.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Boyack, B.E.; Steiner, J.L.; Harmony, S.C.

The PIUS advanced reactor is a 640-MWe pressurized water reactor concept developed by Asea Brown Boveri. A unique feature of PIUS is the absence of mechanical control and shutdown rods. Reactivity is controlled by coolant boron concentration and the temperature of the moderator coolant. Los Alamos is supporting the US Nuclear Regulatory Commission`s preapplication review of the PIUS reactor. Baseline calculations of the PIUS design were performed for a loss of offsite power initiator using TRAC-PF1/MOD2. Additional sensitivity studies examined flow blockage and boron dilution events to explore the robustness of the PIUS concept for low-probability combination events following amore » loss of offsite power.« less

A numerical analysis to evaluate Betz's Law for vertical axis wind turbines

NASA Astrophysics Data System (ADS)

Thönnißen, F.; Marnett, M.; Roidl, B.; Schröder, W.

2016-09-01

The upper limit for the energy conversion rate of horizontal axis wind turbines (HAWT) is known as the Betz limit. Often this limit is also applied to vertical axis wind turbines (VAWT). However, a literature review reveals that early analytical and recent numerical approaches predicted values for the maximum power output of VAWTs close to or even higher than the Betz limit. Thus, it can be questioned whether the application of Betz's Law to VAWTs is justified. To answer this question, the current approach combines a free vortex model with a 2D inviscid panel code to represent the flow field of a generic VAWT. To ensure the validity of the model, an active blade pitch control system is used to avoid flow separation. An optimal pitch curve avoiding flow separation is determined for one specific turbine configuration by applying an evolutionary algorithm. The analysis yields a net power output that is slightly (≈6%) above the Betz limit. Besides the numerical result of an increased energy conversion rate, especially the identification of two physical power increasing mechanisms shows, that the application of Betz's Law to VAWTs is not justified.