Control of a resonant d.c.-link converter for a.c. motor drives

Directory of Open Access Journals (Sweden)

Astrid Petterteig

1992-10-01

Full Text Available This paper presents the control of the resonant d.c.-link converter for a.c. motor drives. This is a low loss converter with higher efficiency than a conventional PWM converter, but it requires complex control. It needs a special control of the resonant d.c.-link voltage in addition to the discrete control of the a.c. side currents. Simulations show how the control of the a.c. currents, the modulation principle, influences the overall performance of the converter.

Design and implementation of co-operative control strategy for hybrid AC/DC microgrids

Science.gov (United States)

Mahmud, Rasel

This thesis is mainly divided in two major sections: 1) Modeling and control of AC microgrid, DC microgrid, Hybrid AC/DC microgrid using distributed co-operative control, and 2) Development of a four bus laboratory prototype of an AC microgrid system. At first, a distributed cooperative control (DCC) for a DC microgrid considering the state-of-charge (SoC) of the batteries in a typical plug-in-electric-vehicle (PEV) is developed. In DC microgrids, this methodology is developed to assist the load sharing amongst the distributed generation units (DGs), according to their ratings with improved voltage regulation. Subsequently, a DCC based control algorithm for AC microgrid is also investigated to improve the performance of AC microgrid in terms of power sharing among the DGs, voltage regulation and frequency deviation. The results validate the advantages of the proposed methodology as compared to traditional droop control of AC microgrid. The DCC-based control methodology for AC microgrid and DC microgrid are further expanded to develop a DCC-based power management algorithm for hybrid AC/DC microgrid. The developed algorithm for hybrid microgrid controls the power flow through the interfacing converter (IC) between the AC and DC microgrids. This will facilitate the power sharing between the DGs according to their power ratings. Moreover, it enables the fixed scheduled power delivery at different operating conditions, while maintaining good voltage regulation and improved frequency profile. The second section provides a detailed explanation and step-by-step design and development of an AC/DC microgrid testbed. Controllers for the three-phase inverters are designed and tested on different generation units along with their corresponding inductor-capacitor-inductor (LCL) filters to eliminate the switching frequency harmonics. Electric power distribution line models are developed to form the microgrid network topology. Voltage and current sensors are placed in the proper

Flexible AC transmission systems modelling and control

CERN Document Server

Zhang, Xiao-Ping; Pal, Bikash

2012-01-01

The extended and revised second edition of this successful monograph presents advanced modeling, analysis and control techniques of Flexible AC Transmission Systems (FACTS). The book covers comprehensively a range of power-system control problems: from steady-state voltage and power flow control, to voltage and reactive power control, to voltage stability control, to small signal stability control using FACTS controllers. In the six years since the first edition of the book has been published research on the FACTS has continued to flourish while renewable energy has developed into a mature and

On-Chip AC self-test controller

Science.gov (United States)

Flanagan, John D [Rhinebeck, NY; Herring, Jay R [Poughkeepsie, NY; Lo, Tin-Chee [Fishkill, NY

2009-09-29

A system for performing AC self-test on an integrated circuit that includes a system clock for normal operation is provided. The system includes the system clock, self-test circuitry, a first and second test register to capture and launch test data in response to a sequence of data pulses, and a logic circuit to be tested. The self-test circuitry includes an AC self-test controller and a clock splitter. The clock splitter generates the sequence of data pulses including a long data capture pulse followed by an at speed data launch pulse and an at speed data capture pulse followed by a long data launch pulse. The at speed data launch pulse and the at speed data capture pulse are generated for a common cycle of the system clock.

Droop-free Team-oriented Control for AC Distribution Systems

DEFF Research Database (Denmark)

Nasirian, Vahidreza; Shafiee, Qobad; Guerrero, Josep M.

2015-01-01

Droop control is conventionally used for load sharing in AC distribution systems. Despite decentralized nature of the droop technique, it requires centralized secondary control to provide voltage and frequency regulation across the system. Distributed control, as an alternative to the centralized...

Interlink Converter with Linear Quadratic Regulator Based Current Control for Hybrid AC/DC Microgrid

Directory of Open Access Journals (Sweden)

Dwi Riana Aryani

2017-11-01

Full Text Available A hybrid alternate current/direct current (AC/DC microgrid consists of an AC subgrid and a DC subgrid, and the subgrids are connected through the interlink bidirectional AC/DC converter. In the stand-alone operation mode, it is desirable that the interlink bidirectional AC/DC converter manages proportional power sharing between the subgrids by transferring power from the under-loaded subgrid to the over-loaded one. In terms of system security, the interlink bidirectional AC/DC converter takes an important role, so proper control strategies need to be established. In addition, it is assumed that a battery energy storage system is installed in one subgrid, and the coordinated control of interlink bidirectional AC/DC converter and battery energy storage system converter is required so that the power sharing scheme between subgrids becomes more efficient. For the purpose of designing a tracking controller for the power sharing by interlink bidirectional AC/DC converter in a hybrid AC/DC microgrid, a droop control method generates a power reference for interlink bidirectional AC/DC converter based on the deviation of the system frequency and voltages first and then interlink bidirectional AC/DC converter needs to transfer the power reference to the over-loaded subgrid. For efficiency of this power transferring, a linear quadratic regulator with exponential weighting for the current regulation of interlink bidirectional AC/DC converter is designed in such a way that the resulting microgrid can operate robustly against various uncertainties and the power sharing is carried out quickly. Simulation results show that the proposed interlink bidirectional AC/DC converter control strategy provides robust and efficient power sharing scheme between the subgrids without deteriorating the secure system operation.

Protective and control relays as coal-mine power-supply ACS subsystem

Science.gov (United States)

Kostin, V. N.; Minakova, T. E.

2017-10-01

The paper presents instantaneous selective short-circuit protection for the cabling of the underground part of a coal mine and central control algorithms as a Coal-Mine Power-Supply ACS Subsystem. In order to improve the reliability of electricity supply and reduce the mining equipment down-time, a dual channel relay protection and central control system is proposed as a subsystem of the coal-mine power-supply automated control system (PS ACS).

An improved power control strategy for hybrid AC-DC microgrids

DEFF Research Database (Denmark)

Baharizadeh, Mehdi; Karshenas, Hamid Reza; Guerrero, Josep M.

2018-01-01

This paper presents a new droop-based control strategy for hybrid microgrids (HMG) with improved power sharing. When ac microgrids (AC-MG) and dc microgrids (DC-MG) are present in a distribution grid, there is an opportunity to interconnect them via an interlinking converter (IC) and form a HMG......, the possibility of participation of IC in AC-MG reactive power adds some complexity to a HMG control system. In this paper, a new decentralized control strategy is presented for a HMG which relies on regulating the voltage magnitude of a common bus in each microgrid. In this regard, new droop characteristics...... for sources across both microgrids as well as IC are proposed. The proposed droop characteristics result in better active/reactive power sharing across both microgrids and at the same time results in better voltage regulation. The derivation of new droop characteristics is thoroughly discussed in this paper...

PWM CONTROLLER'S MODELS FOR INVESTIGATION ACS IN SPICEFAMILY ECAD PROGRAMS

Directory of Open Access Journals (Sweden)

O. V. VASYLENKO

2018-05-01

Full Text Available Purpose. To improve simulation and design of Automatic Control Systems in the SPICE-compatible programs and to obtain separate economic and universal macromodels of PWM controller. Development of an PWM controller economical macromodel for the study of automatic control systems (ACS in computer-aided design (ECAD  programs, which does not generate algorithmic failures in comparison with the existing models of PWM. Findings. Analysis of SPICE-family applications’ mathematical basis allowed to classifying existing models of PWM-controllers, defining their suitability for ACS simulation. The criteria for the synthesis of new models have been defined. For the SPICE 3G algorithms, the Switch and Averaged models based on behavioral elements has been developed. Universal and economical PWM controller macromodel based on the simple algorithm for determining the output signal with minimum numbers of input parameters has been designed. For the Automated Measuring magnetic susceptibility System, the macromodel of quasi-PWM signal generator have been designed, which is used in the compensation subsystem. This model is different from the existing ones: it synthesizes the staircase output signal instead the pulse one, thus, there is direct control of the amplitude of the output signal, which is taken averaged. The adequacy of the models is confirmed as comparison of the simulation results during investigations of the model already existing in the SPICE program, as well as the results of experiments with real ACS. The modeling of the PWM controller was carried out on the basis of behavioral elements from the ECAD library, simulation (solution of algebra-differential equations systems with programming elements is based on SPICE algorithms. The object of the study was the simulation process of ACS with the pulse-width principle of adjusting the output value. The subject of the research are the models of PWM controllers. Originality. The new macromodel of PWM

PREVENTION AND CONTROL OF TUBERCULOSIS *A.C. Okoh ...

African Journals Online (AJOL)

drclement

*A.C. Okoh. Department of Community Health, University of Teaching Hospital Benin City,. Nigeria ... tuberculosis to be a global emergency. There is an ... laboratory capacity as few laboratories are ... control: Survelliance, planning, financing.

Distributed Control for Autonomous Operation of a Three-Port AC/DC/DS Hybrid Microgrid

DEFF Research Database (Denmark)

Wang, Peng; Jin, Chi; Zhu, Dexuan

2015-01-01

This paper presents a distributed control scheme for reliable autonomous operation of a hybrid three-port ac/dc/distributed storage (ds) microgrid by means of power sharing in individual network, power exchange between ac and dc networks, and power management among three networks. The proposed...... distributed control scheme includes: 1) a fully decentralized control, which is achieved by local power sharing (LPS) in individual ac or dc network, global power sharing (GPS) throughout ac/dc networks, and storage power sharing (SPS) among distributed storages. Upon fully decentralized control, each power...... module can operate independently without communication links. This would benefit for riding through communication malfunction in multilayer supervision control system; 2) a multilevel power exchange control for scheduling LPS, GPS, and SPS has been developed to reduce unnecessary power exchange between...

System and Battery Charge Control for PV-Powered AC Lighting Systems

Energy Technology Data Exchange (ETDEWEB)

Kern, G.

1999-04-01

This report reviews a number of issues specific to stand-alone AC lighting systems. A review of AC lighting technology is presented, which discusses the advantages and disadvantages of various lamps. The best lamps for small lighting systems are compact fluorescent. The best lamps for intermediate-size systems are high- or low-pressure sodium. Specifications for battery charging and load control are provided with the goal of achieving lamp lifetimes on the order of 16,000 to 24,000 hours and battery lifetimes of 4 to 5 years. A rough estimate of the potential domestic and global markets for stand-alone AC lighting systems is presented. DC current injection tests were performed on high-pressure sodium lamps and the test results are presented. Finally, a prototype system was designed and a prototype system controller (with battery charger and DC/AC inverter) was developed and built.

Advanced AC Motor Control

Energy Technology Data Exchange (ETDEWEB)

Kazmierkowski, M.P. [Institute of Control and Industrial Electronics, Warsaw University of Technology, Warszawa (Poland)

1997-12-31

In this paper a review of control methods for high performance PWM inverter-fed induction motor drives is presented. Starting from the description of an induction motor by the help of the space vectors, three basic control strategic are discussed. As first, the most popular Field Oriented Control (FOC) is described. Secondly, the Direct Torque and Flux vector Control (DTFC) method, which - in contrast to FOC - depart from idea of coordinate transformation and analogy with DC motor, is briefly characterized. The last group is based on Feedback Linearization Control (FLC) and can be easy combined with sliding mode control. The simulation and experimental oscillograms that illustrate the performance of the discussed control strategies are shown. (orig.) 35 refs.

AC – AC Converters for UPS

Directory of Open Access Journals (Sweden)

Rusalin Lucian R. Păun

2008-05-01

Full Text Available This paper propose a new control technique forsingle – phase AC – AC converters used for a on-line UPSwith a good dynamic response, a reduced-partscomponents, a good output characteristic, a good powerfactorcorrection(PFC. This converter no needs anisolation transformer. A power factor correction rectifierand an inverter with the proposed control scheme has beendesigned and simulated using Caspoc2007, validating theconcept.

Sensorless Vector Control of AC Induction Motor Using Sliding-Mode Observer

Directory of Open Access Journals (Sweden)

Phuc Thinh Doan

2013-06-01

Full Text Available This paper develops a sensorless vector controlled method for AC induction motor using sliding-mode observer. For developing the control algorithm, modeling of AC induction motor is presented. After that, a sliding mode observer is proposed to estimate the motor speed, the rotor flux, the angular position of the rotor flux and the motor torque from monitored stator voltages and currents. The use of the nonlinear sliding mode observer provides very good performance for both low and high speed motor operation. Furthermore, the proposed system is robust in motor losses and load variations. The convergence of the proposed observer is obtained using the Lyapunov theory. Hardware and software for simulation and experiment of the AC induction motor drive are introduced. The hardware consists of a 1.5kw AC induction motor connected in series with a torque sensor and a powder brake. A controller is developed based on DSP TMS320F28355. The simulation and experimental results illustrate that fast torque and speed response with small torque ripples can be achieved. The proposed control scheme is suitable to the application fields that require high performance of torque response such as electric vehicles. doi:http://dx.doi.org/10.12777/ijse.4.2.2013.39-43 [How to cite this article: Doan, P. T., Nguyen, T. T., Jeong, S. K., Oh, S. J., & Kim, S. B. (2013. Sensorless Vector Control of AC Induction Motor Using Sliding-Mode Observer. INTERNATIONAL JOURNAL OF SCIENCE AND ENGINEERING, 4(2, 39-43; doi: http://dx.doi.org/10.12777/ijse.4.2.2013.39-43

Control of grid interactive AC microgrids

DEFF Research Database (Denmark)

Wang, Xiongfei; Guerrero, Josep M.; Chen, Zhe

2010-01-01

Over the last decade, distributed energy resources (DER) technology has undergone a fast development. Increased penetration of DER units and wide spread use of renewable energy sources challenge the entire architecture of traditional power system. Microgrid, characterizing higher flexibility......, microgrid controls and power management strategies are presented. Future trends of microgrid are discussed pointing out how this concept can be a key to achieve a more intelligent and flexible AC grid....

System and method for monitoring and controlling stator winding temperature in a de-energized AC motor

Science.gov (United States)

Lu, Bin [Kenosha, WI; Luebke, Charles John [Sussex, WI; Habetler, Thomas G [Snellville, GA; Zhang, Pinjia [Atlanta, GA; Becker, Scott K [Oak Creek, WI

2011-12-27

A system and method for measuring and controlling stator winding temperature in an AC motor while idling is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of a multi-phase AC motor. The circuit further includes a plurality of switching devices to control current flow and terminal voltages in the multi-phase AC motor and a controller connected to the circuit. The controller is configured to activate the plurality of switching devices to create a DC signal in an output of the motor control device corresponding to an input to the multi-phase AC motor, determine or estimate a stator winding resistance of the multi-phase AC motor based on the DC signal, and estimate a stator temperature from the stator winding resistance. Temperature can then be controlled and regulated by DC injection into the stator windings.

Team-oriented Adaptive Droop Control for Autonomous AC Microgrids

DEFF Research Database (Denmark)

Shafiee, Qobad; Nasirian, Vahidreza; Guerrero, Josep M.

2014-01-01

This paper proposes a distributed control strategy for voltage and reactive power regulation in ac Microgrids. First, the control module introduces a voltage regulator that maintains the average voltage of the system on the rated value, keeping all bus voltages within an acceptable range. Dynamic...

Controlled formation of metallic nanowires via Au nanoparticle ac trapping

International Nuclear Information System (INIS)

Bernard, L; Calame, M; Molen, S J van der; Liao, J; Schoenenberger, C

2007-01-01

Applying ac voltages, we trapped gold nanoparticles between micro-fabricated electrodes under well-defined conditions. We demonstrate that the nanoparticles can be controllably fused together to form homogeneous gold nanowires with pre-defined diameters and conductance values. Whereas electromigration is known to form a gap when a dc voltage is applied, this ac technique achieves the opposite, thereby completing the toolkit for the fabrication of nanoscale junctions

Controlled formation of metallic nanowires via Au nanoparticle ac trapping

Energy Technology Data Exchange (ETDEWEB)

Bernard, L; Calame, M; Molen, S J van der; Liao, J; Schoenenberger, C [Institute of Physics, University of Basel, CH-4056 Basel (Switzerland)

2007-06-13

Applying ac voltages, we trapped gold nanoparticles between micro-fabricated electrodes under well-defined conditions. We demonstrate that the nanoparticles can be controllably fused together to form homogeneous gold nanowires with pre-defined diameters and conductance values. Whereas electromigration is known to form a gap when a dc voltage is applied, this ac technique achieves the opposite, thereby completing the toolkit for the fabrication of nanoscale junctions.

Methods, systems and apparatus for controlling operation of two alternating current (AC) machines

Science.gov (United States)

Gallegos-Lopez, Gabriel [Torrance, CA; Nagashima, James M [Cerritos, CA; Perisic, Milun [Torrance, CA; Hiti, Silva [Redondo Beach, CA

2012-02-14

A system is provided for controlling two AC machines. The system comprises a DC input voltage source that provides a DC input voltage, a voltage boost command control module (VBCCM), a five-phase PWM inverter module coupled to the two AC machines, and a boost converter coupled to the inverter module and the DC input voltage source. The boost converter is designed to supply a new DC input voltage to the inverter module having a value that is greater than or equal to a value of the DC input voltage. The VBCCM generates a boost command signal (BCS) based on modulation indexes from the two AC machines. The BCS controls the boost converter such that the boost converter generates the new DC input voltage in response to the BCS. When the two AC machines require additional voltage that exceeds the DC input voltage required to meet a combined target mechanical power required by the two AC machines, the BCS controls the boost converter to drive the new DC input voltage generated by the boost converter to a value greater than the DC input voltage.

Development of magneto-rheologial fluid (MRF) based clutch for output torque control of AC motors

Science.gov (United States)

Nguyen, Q. Hung; Do, H. M. Hieu; Nguyen, V. Quoc; Nguyen, N. Diep; Le, D. Thang

2018-03-01

In industry, the AC motor is widely used because of low price, power availability, low cost maintenance. The main disadvantages of AC motors compared to DC motors are difficulty in speed and torque control, requiring expensive controllers with complex control algorithms. This is the basic limitations in the widespread adoption of AC motor systems for industrial automation. One feasible solution for AC motor control is using MRF (magneto-rheological fluid) based clutches (shortly called MR clutches) Although there have been many studies on MR clutches, most of these clutches used traditional configuration with coils wound on the middle cylindrical part and a compotator is used to supply power to the coils. Therefore, this type of MR clutches possesses many disadvantages such as high friction and unstable applied current due to commutator, complex structure which causes difficulty in manufacture, assembly, and maintenance. In addition, the bottleneck problem of magnetic field is also a challenging issue. In this research, we will develop a new type of MR clutches that overcomes the abovementioned disadvantages of traditional MR clutches and more suitable for application in controlling of AC motor. Besides, in this study, speed and torque control system for AC motors using developed MR clutches is designed and experimental validated.

Multi-phase AC/AC step-down converter for distribution systems

Science.gov (United States)

Aeloiza, Eddy C.; Burgos, Rolando P.

2017-10-25

A step-down AC/AC converter for use in an electric distribution system includes at least one chopper circuit for each one of a plurality of phases of the AC power, each chopper circuit including a four-quadrant switch coupled in series between primary and secondary sides of the chopper circuit and a current-bidirectional two-quadrant switch coupled between the secondary side of the chopper circuit and a common node. Each current-bidirectional two-quadrant switch is oriented in the same direction, with respect to the secondary side of the corresponding chopper circuit and the common node. The converter further includes a control circuit configured to pulse-width-modulate control inputs of the switches, to convert a first multiphase AC voltage at the primary sides of the chopper circuits to a second multiphase AC voltage at the secondary sides of the chopper circuits, the second multiphase AC voltage being lower in voltage than the first multiphase AC voltage.

ac power control in the Core Flow Test Loop

International Nuclear Information System (INIS)

McDonald, D.W.

1980-01-01

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

AC machine control : robust and sensorless control by parameter independency

Energy Technology Data Exchange (ETDEWEB)

Samuelsen, Dag Andreas Hals

2009-06-15

In this thesis it is first presented how robust control can be used to give AC motor drive systems competitive dynamic performance under parameter variations. These variations are common to all AC machines, and are a result of temperature change in the machine, and imperfect machine models. This robust control is, however, dependent on sensor operation in the sense that the rotor position is needed in the control loop. Elimination of this control loop has been for many years, and still is, a main research area of AC machines control systems. An integrated PWM modulator and sampler unit has been developed and tested. The sampler unit is able to give current and voltage measurements with a reduced noise component. It is further used to give the true derivative of currents and voltages in the machine and the power converter, as an average over a PWM period, and as separate values for all states of the power converter. In this way, it can give measurements of the currents as well as the derivative of the currents, at the start and at the end of a single power inverter state. This gave a large degree of freedom in parameter and state identification during uninterrupted operation of the induction machine. The special measurement scheme of the system achieved three main goals: By avoiding the time frame where the transistors commutate and the noise in the measurement of the current is large, filtering of the current measurement is no longer needed. The true derivative of the current in the machine is can be measured with far less noise components. This was extended to give any separate derivative in all three switching states of the power converter. Using the computational resources of the FPGA, more advanced information was supplied to the control system, in order to facilitate sensor less operation, with low computational demands on the DSP. As shown in the papers, this extra information was first used to estimate some of the states of the machine, in some or all of the

Fuzzy Secondary Controller for Autonomous Stand-alone and Grid-connected AC Microgrid

DEFF Research Database (Denmark)

Neves, Rodolpho V. A.; Machado, Ricardo Q.; Oliveira, Vilma A.

2016-01-01

The present paper adresses the AC microgrid control issue using the hierarchical control structure and droop controllers for load sharing. Once the droop controllers impose an operation with frequency and voltage deviations, depending on the load and droop parameters, a hierarchical control...... structure must be added to change the droop controller operating points. The hierarchical controllers operate with local measurements and shared signals from communication links among the distributed generation systems connected to the microgrid. Depending on the geographical size of the microgrid......, the communication links can be economically unviable. This paper thus proposes a fuzzy secondary controller for AC microgrids to reduce the link communication dependency by using only local measurements. The simulation results show that the deviations as happened with the conventional secondary controllers can...

Bearingless AC Homopolar Machine Design and Control for Distributed Flywheel Energy Storage

Science.gov (United States)

Severson, Eric Loren

The increasing ownership of electric vehicles, in-home solar and wind generation, and wider penetration of renewable energies onto the power grid has created a need for grid-based energy storage to provide energy-neutral services. These services include frequency regulation, which requires short response-times, high power ramping capabilities, and several charge cycles over the course of one day; and diurnal load-/generation-following services to offset the inherent mismatch between renewable generation and the power grid's load profile, which requires low self-discharge so that a reasonable efficiency is obtained over a 24 hour storage interval. To realize the maximum benefits of energy storage, the technology should be modular and have minimum geographic constraints, so that it is easily scalable according to local demands. Furthermore, the technology must be economically viable to participate in the energy markets. There is currently no storage technology that is able to simultaneously meet all of these needs. This dissertation focuses on developing a new energy storage device based on flywheel technology to meet these needs. It is shown that the bearingless ac homopolar machine can be used to overcome key obstacles in flywheel technology, namely: unacceptable self-discharge and overall system cost and complexity. Bearingless machines combine the functionality of a magnetic bearing and a motor/generator into a single electromechanical device. Design of these machines is particularly challenging due to cross-coupling effects and trade-offs between motor and magnetic bearing capabilities. The bearingless ac homopolar machine adds to these design challenges due to its 3D flux paths requiring computationally expensive 3D finite element analysis. At the time this dissertation was started, bearingless ac homopolar machines were a highly immature technology. This dissertation advances the state-of-the-art of these machines through research contributions in the areas of

Coordinated Control Scheme for Ancillary Services from Offshore Wind Power Plants to AC and DC Grids

DEFF Research Database (Denmark)

Sakamuri, Jayachandra N.; Altin, Müfit; Hansen, Anca Daniela

2016-01-01

This paper proposes a new approach of providing ancillary services to AC and DC grids from offshore wind power plants (OWPPs), connected through multi-terminal HVDC network. A coordinated control scheme where OWPP’s AC grid frequency modulated according to DC grid voltage variations is used...... to detect and provide the ancillary service requirements of both AC and DC grids, is proposed in this paper. In particular, control strategies for onshore frequency control, fault ridethrough support in the onshore grid, and DC grid voltage control are considered. The proposed control scheme involves only...

Enhanced DC-Link Capacitor Voltage Balancing Control of DC–AC Multilevel Multileg Converters

DEFF Research Database (Denmark)

Busquets-Monge, Sergio; Maheshwari, Ram Krishan; Nicolas-Apruzzese, Joan

2015-01-01

This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc-link vol......This paper presents a capacitor voltage balancing control applicable to any multilevel dc–ac converter formed by a single set of series-connected capacitors implementing the dc link and semiconductor devices, such as the diode-clamped topology. The control is defined for any number of dc...

A Secondary Voltage Control Method for an AC/DC Coupled Transmission System Based on Model Predictive Control

DEFF Research Database (Denmark)

Xu, Fengda; Guo, Qinglai; Sun, Hongbin

2015-01-01

For an AC/DC coupled transmission system, the change of transmission power on the DC lines will significantly influence the AC systems’ voltage. This paper describes a method to coordinated control the reactive power of power plants and shunt capacitors at DC converter stations nearby, in order t...

Improved SCR ac Motor Controller for Battery Powered Urban Electric Vehicles

Science.gov (United States)

Latos, T. S.

1982-01-01

An improved ac motor controller, which when coupled to a standard ac induction motor and a dc propulsion battery would provide a complete electric vehicle power train with the exception of the mechanical transmission and drive wheels was designed. In such a system, the motor controller converts the dc electrical power available at the battery terminals to ac electrical power for the induction motor in response to the drivers commands. The performance requirements of a hypothetical electric vehicle with an upper weight bound of 1590 kg (3500 lb) were used to determine the power rating of the controller. Vehicle acceleration capability, top speed, and gradeability requisites were contained in the Society of Automotive Engineers (SAE) Schedule 227a(d) driving cycle. The important capabilities contained in this driving cycle are a vehicle acceleration requirement of 0 to 72.4 kmph (0 to 45 mph) in 28 seconds a top speed of 88.5 kmph (55 mph), and the ability to negotiate a 10% grade at 48 kmph (30 mph). A 10% grade is defined as one foot of vertical rise per 10 feet of horizontal distance.

Introduction to AC machine design

CERN Document Server

Lipo, Thomas A

2018-01-01

AC electrical machine design is a key skill set for developing competitive electric motors and generators for applications in industry, aerospace, and defense. This book presents a thorough treatment of AC machine design, starting from basic electromagnetic principles and continuing through the various design aspects of an induction machine. Introduction to AC Machine Design includes one chapter each on the design of permanent magnet machines, synchronous machines, and thermal design. It also offers a basic treatment of the use of finite elements to compute the magnetic field within a machine without interfering with the initial comprehension of the core subject matter. Based on the author's notes, as well as after years of classroom instruction, Introduction to AC Machine Design: * Brings to light more advanced principles of machine design--not just the basic principles of AC and DC machine behavior * Introduces electrical machine design to neophytes while also being a resource for experienced designers * ...

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

Science.gov (United States)

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.

Coordinated control of three-phase AC and DC type EV–ESSs for efficient hybrid microgrid operations

International Nuclear Information System (INIS)

Rahman, Md Shamiur; Hossain, M.J.; Lu, Junwei

2016-01-01

Highlights: • A coordinated control is proposed for three-phase AC and DC type electric vehicles. • A four-quadrant interlinking converter is designed for hybrid microgrid operations. • Concurrent real irradiation data and commercial load profile are used for testing. • Unbalanced scenario due to single-phase electric vehicle charging is considered. • Improved AC and DC bus voltages and frequency regulations are achieved. - Abstract: This paper presents a three-layered coordinated control to incorporate three-phase (3P) alternating current (AC) and direct current (DC) type electric vehicle energy storage systems (EV–ESSs) for improved hybrid AC/DC microgrid operations. The first layer of the algorithm ensures DC subgrid management by regulating the DC bus voltage and DC side power management. The second and third layer manages AC subgrid by regulating the AC bus voltage and the frequency by managing reactive and active power respectively. The multi-layered coordination is embedded into the microgrid central controller (MGCC) which controls the interlinking controller in between AC and DC microgrid and the interfacing controllers of the participating electric vehicles (EVs) and distributed generation (DG) units. The whole system is designed in MATLAB/SIMULINK® environment resembling the under construction microgrid at Griffith University, Australia. Extensive case studies are performed using real life irradiation data and commercial loads of the campus buildings. Impacts of homogeneous and heterogeneous single-phase EV charging are investigated to observe both balanced and unbalanced scenarios. Synchronization during the transition from the islanded to grid-tied mode is tested considering a contingency situation. From the comparative simulation results it is evident that the proposed controller exhibits effective, reliable and robust performance for all the cases.

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

DEFF Research Database (Denmark)

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

2015-01-01

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

Implementation of Genetic Algorithm in Control Structure of Induction Motor A.C. Drive

Directory of Open Access Journals (Sweden)

BRANDSTETTER, P.

2014-11-01

Full Text Available Modern concepts of control systems with digital signal processors allow the implementation of time-consuming control algorithms in real-time, for example soft computing methods. The paper deals with the design and technical implementation of a genetic algorithm for setting proportional and integral gain of the speed controller of the A.C. drive with the vector-controlled induction motor. Important simulations and experimental measurements have been realized that confirm the correctness of the proposed speed controller tuned by the genetic algorithm and the quality speed response of the A.C. drive with changing parameters and disturbance variables, such as changes in load torque.

Analysis and control of induction generator supplying stand-alone AC loads employing a Matrix Converter

Directory of Open Access Journals (Sweden)

Sumedha Mahajan

2017-04-01

Full Text Available This paper proposes a Capacitor Excited Induction Generator (CEIG-Matrix Converter (MC system for feeding stand-alone AC loads. The variable output voltage magnitude and frequency from CEIG is converted into a constant voltage magnitude and frequency at the load terminals by controlling MC using Space Vector Modulation (SVM technique. This single-stage MC is turned up as a good alternative for the proposed system against commonly used AC/DC/AC two stage power converters. The configuration and implementation of the closed-loop control scheme employing dSPACE 1103 real time controller have been fully described in the paper. The proposed closed-loop controller regulates the AC load voltage irrespective of changes in the prime mover speed and load. A method for predetermining the steady-state performance of the proposed system has been developed and described with relevant analytical expressions. The effectiveness of the proposed system is exemplified through simulation results for various operating conditions. The proposed control technique is further validated using an experimental setup developed in the laboratory.

Sliding-Mode Control Design of a Boost-Buck Switching Converter for AC Signal Generation

OpenAIRE

Biel Solé, Domingo; Guinjoan Gispert, Francisco; Fossas Colet, Enric; Chavarría Roé, Javier

2004-01-01

This paper presents a sliding-mode control design of a boost–buck switching converter for a voltage step-up dc–ac conversion without the use of any transformer. This approach combines the step-up/step-down conversion ratio capability of the converter with the robustness properties of sliding-mode control. The proposed control strategy is based on the design of two slidingcontrol laws, one ensuring the control of a full-bridge buck converter for proper dc–ac conversion, and the other one the c...

Sensorless AC electric motor control robust advanced design techniques and applications

CERN Document Server

Glumineau, Alain

2015-01-01

This monograph shows the reader how to avoid the burdens of sensor cost, reduced internal physical space, and system complexity in the control of AC motors. Many applications fields—electric vehicles, wind- and wave-energy converters and robotics, among them—will benefit. Sensorless AC Electric Motor Control describes the elimination of physical sensors and their replacement with observers, i.e., software sensors. Robustness is introduced to overcome problems associated with the unavoidable imperfection of knowledge of machine parameters—resistance, inertia, and so on—encountered in real systems. The details of a large number of speed- and/or position-sensorless ideas for different types of permanent-magnet synchronous motors and induction motors are presented along with several novel observer designs for electrical machines. Control strategies are developed using high-order, sliding-mode and quasi-continuous-sliding-mode techniques and two types of observer–controller schemes based on backstepping ...

Analysis of an AC-DC full-controlled converter supplying two DC-Series-Motor loads

International Nuclear Information System (INIS)

Al-Hindawi, Mohammed M.; Al-Turki, Yusuf A.; Al-Subaie, Obaid T.

2000-01-01

Phase-controlled converters are widely used because these converters are simple, less expensive, reliable, and do not require any communication circuit. Series motors are extensively used in many applications that require both high starting torque and essentially constant horse power. This paper is concerned with the detailed study of the performance characteristics of an AC-DC full-controlled converter supplying two DC-series-motor loads. The converter loads combination is simulated on a digital computer. Different modes of operation (continuous and discontinuous converter currents) are considered. The critical firing angle at which the mode of operation changes from one mode to another is deduced. The performance characteristics such input power factor, supply current distortion factor, supply current fundamental power factor, torque speed, and motor current ripple factor have been derived and studied for both constant firing angle and constant load factor have been derived and studied for both constant firing angle and constant load power of one motor. Waveforms for each load current and converter current are investigated for different modes of operation. (author)

A New Coordinated Voltage Control Scheme for Offshore AC Grid of HVDC Connected Offshore Wind Power Plants

DEFF Research Database (Denmark)

Sakamuri, Jayachandra N.; Cutululis, Nicolaos Antonio; Rather, Zakir Hussain

2015-01-01

This paper proposes a coordinated voltage control scheme (CVCS) which enhances the voltage ride through (VRT) capability of an offshore AC grid comprised of a cluster of offshore wind power plants (WPP) connected through AC cables to the offshore voltage source converter based high voltage DC (VSC......-HVDC) converter station. Due to limited short circuit power contribution from power electronic interfaced variable speed wind generators and with the onshore main grid decoupled by the HVDC link, the offshore AC grid becomes more vulnerable to dynamic voltage events. Therefore, a short circuit fault...... in the offshore AC Grid is likely to have significant implications on the voltage of the offshore AC grid, hence on the power flow to the onshore mainland grid. The proposed CVCS integrates individual local reactive power control of wind turbines and of the HVDC converter with the secondary voltage controller...

Engine-start Control Strategy of P2 Parallel Hybrid Electric Vehicle

Science.gov (United States)

Xiangyang, Xu; Siqi, Zhao; Peng, Dong

2017-12-01

A smooth and fast engine-start process is important to parallel hybrid electric vehicles with an electric motor mounted in front of the transmission. However, there are some challenges during the engine-start control. Firstly, the electric motor must simultaneously provide a stable driving torque to ensure the drivability and a compensative torque to drag the engine before ignition. Secondly, engine-start time is a trade-off control objective because both fast start and smooth start have to be considered. To solve these problems, this paper first analyzed the resistance of the engine start process, and established a physic model in MATLAB/Simulink. Then a model-based coordinated control strategy among engine, motor and clutch was developed. Two basic control strategy during fast start and smooth start process were studied. Simulation results showed that the control objectives were realized by applying given control strategies, which can meet different requirement from the driver.

An estimator-based distributed voltage-predictive control strategy for ac islanded microgrids

DEFF Research Database (Denmark)

Wang, Yanbo; Chen, Zhe; Wang, Xiongfei

2015-01-01

This paper presents an estimator-based voltage predictive control strategy for AC islanded microgrids, which is able to perform voltage control without any communication facilities. The proposed control strategy is composed of a network voltage estimator and a voltage predictive controller for each...... and has a good capability to reject uncertain perturbations of islanded microgrids....

Hierarchical Control of Droop-Controlled DC and AC Microgrids - A General Approach Towards Standardization

DEFF Research Database (Denmark)

Guerrero, Josep M.; Vásquez, Juan V.; Teodorescu, Remus

2009-01-01

DC and AC Microgrids are key elements to integrate renewable and distributed energy resources as well as distributed energy storage systems. In the last years, efforts toward the standardization of these Microgrids have been made. In this sense, this paper present the hierarchical control derived...

Power control of a wind farm with active stall wind turbines and AC grid connection

DEFF Research Database (Denmark)

Hansen, Anca Daniela; Sørensen, Poul; Iov, Florin

both the control on wind turbine level as well as the central control on the wind farm level. The ability of active stall wind farms with AC grid connection to regulate the power production to the reference power ordered by the operators is assessed and discussed by means of simulations.......This paper describes the design of a centralised wind farm controller for a wind farm made-up exclusively of active stall wind turbines with AC grid connection. The overall aim of such controller is to enable the wind farms to provide the best grid support. The designed wind farm control involves...

Adaptive Sliding Mode Control of MEMS AC Voltage Reference Source

Directory of Open Access Journals (Sweden)

Ehsan Ranjbar

2017-01-01

Full Text Available The accuracy of physical parameters of a tunable MEMS capacitor, as the major part of MEMS AC voltage reference, is of great importance to achieve an accurate output voltage free of the malfunctioning noise and disturbance. Even though strenuous endeavors are made to fabricate MEMS tunable capacitors with desiderated accurate physical characteristics and ameliorate exactness of physical parameters’ values, parametric uncertainties ineluctably emerge in fabrication process attributable to imperfections in micromachining process. First off, this paper considers applying an adaptive sliding mode controller design in the MEMS AC voltage reference source so that it is capable of giving off a well-regulated output voltage in defiance of jumbling parametric uncertainties in the plant dynamics and also aggravating external disturbance imposed on the system. Secondly, it puts an investigatory comparison with the designed model reference adaptive controller and the pole-placement state feedback one into one’s prospective. Not only does the tuned adaptive sliding mode controller show remarkable robustness against slow parameter variation and external disturbance being compared to the pole-placement state feedback one, but also it immensely gets robust against the external disturbance in comparison with the conventional adaptive controller. The simulation results are promising.

Thrust distribution for attitude control in a variable thrust propulsion system with four ACS nozzles

Science.gov (United States)

Lim, Yeerang; Lee, Wonsuk; Bang, Hyochoong; Lee, Hosung

2017-04-01

A thrust distribution approach is proposed in this paper for a variable thrust solid propulsion system with an attitude control system (ACS) that uses a reduced number of nozzles for a three-axis attitude maneuver. Although a conventional variable thrust solid propulsion system needs six ACS nozzles, this paper proposes a thrust system with four ACS nozzles to reduce the complexity and mass of the system. The performance of the new system was analyzed with numerical simulations, and the results show that the performance of the system with four ACS nozzles was similar to the original system while the mass of the whole system was simultaneously reduced. Moreover, a feasibility analysis was performed to determine whether a thrust system with three ACS nozzles is possible.

Increased Ac excision (iae): Arabidopsis thaliana mutations affecting Ac transposition

International Nuclear Information System (INIS)

Jarvis, P.; Belzile, F.; Page, T.; Dean, C.

1997-01-01

The maize transposable element Ac is highly active in the heterologous hosts tobacco and tomato, but shows very much reduced levels of activity in Arabidopsis. A mutagenesis experiment was undertaken with the aim of identifying Arabidopsis host factors responsible for the observed low levels of Ac activity. Seed from a line carrying a single copy of the Ac element inserted into the streptomycin phosphotransferase (SPT) reporter fusion, and which displayed typically low levels of Ac activity, were mutagenized using gamma rays. Nineteen mutants displaying high levels of somatic Ac activity, as judged by their highly variegated phenotypes, were isolated after screening the M2 generation on streptomycin-containing medium. The mutations fall into two complementation groups, iae1 and iae2, are unlinked to the SPT::Ac locus and segregate in a Mendelian fashion. The iae1 mutation is recessive and the iae2 mutation is semi-dominant. The iae1 and iae2 mutants show 550- and 70-fold increases, respectively, in the average number of Ac excision sectors per cotyledon. The IAE1 locus maps to chromosome 2, whereas the SPT::Ac reporter maps to chromosome 3. A molecular study of Ac activity in the iae1 mutant confirmed the very high levels of Ac excision predicted using the phenotypic assay, but revealed only low levels of Ac re-insertion. Analyses of germinal transposition in the iae1 mutant demonstrated an average germinal excision frequency of 3% and a frequency of independent Ac re-insertions following germinal excision of 22%. The iae mutants represents a possible means of improving the efficiency of Ac/Ds transposon tagging systems in Arabidopsis, and will enable the dissection of host involvement in Ac transposition and the mechanisms employed for controlling transposable element activity

Distributed Coordination Control Based on State-of-Charge for Bidirectional Power Converters in a Hybrid AC/DC Microgrid

Directory of Open Access Journals (Sweden)

Zeyan Lv

2018-04-01

Full Text Available This paper proposes a distributed coordination control for multiple bidirectional power converters (BPCs in a hybrid AC/DC microgrid with consideration of state-of-charge (SOC of storages. The researched hybrid AC/DC microgrid is composed of both AC and DC subgrids connected by multiple parallel BPCs. In the literature, the storages of a hybrid microgrid are considered to allocate in only the AC subgrid or DC subgrid, which reduces the reliability of the whole system, especially during the islanded mode. Besides, the SOC management has not been considered in BPCs’ operating strategy. This paper considers a hybrid microgrid topology which has energy storages in both AC side and DC side. This ensures the reliability while increasing the complexity of the control strategy at the same time. Further, a distributed coordination control method for multiple BPCs based on SOC was proposed to enhance the reliability of hybrid microgrid. Finally, the performance of the proposed control methods was verified by real-time hardware-in-loop (HIL tests.

Equivalence of Primary Control Strategies for AC and DC Microgrids

Directory of Open Access Journals (Sweden)

Eneko Unamuno

2017-01-01

Full Text Available Microgrid frequency and voltage regulation is a challenging task, as classical generators with rotational inertia are usually replaced by converter-interfaced systems that inherently do not provide any inertial response. The aim of this paper is to analyse and compare autonomous primary control techniques for alternating current (AC and direct current (DC microgrids that improve this transient behaviour. In this context, a virtual synchronous machine (VSM technique is investigated for AC microgrids, and its behaviour for different values of emulated inertia and droop slopes is tested. Regarding DC microgrids, a virtual-impedance-based algorithm inspired by the operation concept of VSMs is proposed. The results demonstrate that the proposed strategy can be configured to have an analogous behaviour to VSM techniques by varying the control parameters of the integrated virtual-impedances. This means that the steady-state and transient behaviour of converters employing these strategies can be configured independently. As shown in the simulations, this is an interesting feature that could be, for instance, employed for the integration of different dynamic generation or storage systems, such as batteries or supercapacitors.

Power Flow Analysis for Low-Voltage AC and DC Microgrids Considering Droop Control and Virtual Impedance

DEFF Research Database (Denmark)

Li, Chendan; Chaudhary, Sanjay Kumar; Savaghebi, Mehdi

2017-01-01

In the low-voltage (LV) ac microgrids (MGs), with a relatively high R/X ratio, virtual impedance is usually adopted to improve the performance of droop control applied to distributed generators (DGs). At the same time, LV dc MG using virtual impedance as droop control is emerging without adequate...... power flow studies. In this paper, power flow analyses for both ac and dc MGs are formulated and implemented. The mathematical models for both types of MGs considering the concept of virtual impedance are used to be in conformity with the practical control of the DGs. As a result, calculation accuracy...... is improved for both ac and dc MG power flow analyses, comparing with previous methods without considering virtual impedance. Case studies are conducted to verify the proposed power flow analyses in terms of convergence and accuracy. Investigation of the impact to the system of internal control parameters...

Fuzzy Controlled Parallel AC-DC Converter for PFC

Directory of Open Access Journals (Sweden)

M Subba Rao

2011-01-01

Full Text Available Paralleling of converter modules is a well-known technique that is often used in medium-power applications to achieve the desired output power by using smaller size of high frequency transformers and inductors. In this paper, a parallel-connected single-phase PFC topology using flyback and forward converters is proposed to improve the output voltage regulation with simultaneous input power factor correction (PFC and control. The goal of the control is to stabilize the output voltage of the converter against the load variations. The paper presents the derivation of fuzzy control rules for the dc/dc converter circuit and control algorithm for regulating the dc/dc converter. This paper presents a design example and circuit analysis for 200 W power supply. The proposed approach offers cost effective, compact and efficient AC/DC converter by the use of parallel power processing. MATLAB/SIMULINK is used for implementation and simulation results show the performance improvement.

Hierarchical Control of Parallel AC-DC Converter Interfaces for Hybrid Microgrids

DEFF Research Database (Denmark)

Lu, Xiaonan; Guerrero, Josep M.; Sun, Kai

2014-01-01

In this paper, a hierarchical control system for parallel power electronics interfaces between ac bus and dc bus in a hybrid microgrid is presented. Both standalone and grid-connected operation modes in the dc side of the microgrid are analyzed. Concretely, a three-level hierarchical control system...... equal or proportional dc load current sharing. The common secondary control level is designed to eliminate the dc bus voltage deviation produced by the droop control, with dc bus voltage in the hybrid microgrid boosted to an acceptable range. After guaranteeing the performance of the dc side standalone...

Control device for start-up of reactor depressurization system

International Nuclear Information System (INIS)

Suzuki, Hiroshi; Saito, Minoru; Oda, Shingo; Miura, Satoshi; Hashimoto, Koji; Tate, Hitoshi; Fujii, Kazunobu

1998-01-01

The present invention concerns are emergency reactor core cooling system (ECCS) of a BWR type reactor and provides a control device for start-up of an automatic depressurization system. Namely, the device has an object of preventing erroneous opening of a main steam escape safety value when testing a start-up signal circuit of an automatic depressurization system for testing the automatic depressurization system. A start-up signal circuit receives both signals of a reactor container pressure high signal and a reactor pressure vessel water level low signal and outputs an automatic start-up signal for compulsorily opening a main steam escape safety valve automatically. A test switch having a self-holding circuit is disposed to a central control chamber. A test signal circuit is disposed for preventing transfer of an erroneous start-up signal to the main steam escape safety valve due to a simulation signal during output test signals by the test switch. (I.S.)

Nonlinear control of voltage source converters in AC-DC power system.

Science.gov (United States)

Dash, P K; Nayak, N

2014-07-01

This paper presents the design of a robust nonlinear controller for a parallel AC-DC power system using a Lyapunov function-based sliding mode control (LYPSMC) strategy. The inputs for the proposed control scheme are the DC voltage and reactive power errors at the converter station and the active and reactive power errors at the inverter station of the voltage-source converter-based high voltage direct current transmission (VSC-HVDC) link. The stability and robust tracking of the system parameters are ensured by applying the Lyapunov direct method. Also the gains of the sliding mode control (SMC) are made adaptive using the stability conditions of the Lyapunov function. The proposed control strategy offers invariant stability to a class of systems having modeling uncertainties due to parameter changes and exogenous inputs. Comprehensive computer simulations are carried out to verify the proposed control scheme under several system disturbances like changes in short-circuit ratio, converter parametric changes, and faults on the converter and inverter buses for single generating system connected to the power grid in a single machine infinite-bus AC-DC network and also for a 3-machine two-area power system. Furthermore, a second order super twisting sliding mode control scheme has been presented in this paper that provides a higher degree of nonlinearity than the LYPSMC and damps faster the converter and inverter voltage and power oscillations. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.

AC ignition of HID lamps

NARCIS (Netherlands)

Sobota, A.; Kanters, J.H.M.; Manders, F.; Veldhuizen, van E.M.; Haverlag, M.

2010-01-01

Our aim was to examine the starting behaviour of mid-pressure argon discharges in pin-pin (point-to-point) geometry, typically used in HID lamps. We focused our work on AC ignition of 300 and 700 mbar Ar discharges in Philips 70W standard burners. Frequency was varied between 200 kHz and 1 MHz. In

Analysis of automobile’s automatic control systems for the hill climbing start

Directory of Open Access Journals (Sweden)

Valeriy I. Klimenko

2014-12-01

Full Text Available To improve road safety while driving on the rise, facilitating the driver’s activity the automobile industry leaders are introducing automatic hill-hold control systems into the car design. This study purpose relates to the existing automatic start control systems’ design analysis. Analyzed are the existing design developments of automatic hill start assist control systems applied for driving at the start of the climbing. The effected research allows to select the scheme for further development of start driving automatic control systems. Further improvement of driving control systems and primarily the driver assistance hill-hold control systems is necessary to increase both the driving comfort and the traffic safety.

Current Control of Grid Converters Connected with Series AC Capacitor

DEFF Research Database (Denmark)

Wang, Xiongfei; Blaabjerg, Frede; Loh, Poh Chiang

2015-01-01

The series ac capacitor has recently been used with the transformerless grid-connected converters in the distribution power grids. The capacitive characteristic of the resulting series LC filter restricts the use of conventional synchronous integral or stationary resonant current controllers. Thus...... this paper proposes a fourth-order resonant controller in the stationary frame, which guarantees a zero steady-state current tracking error for the grid converters with series LC filter. This method is then implemented in a three-phase experimental system for verification, where the current harmonics below...... the LC filter resonance frequency are effectively eliminated. Experimental results confirm the validity of the proposed current control scheme....

Near-optimal order-reduced control for A/C (air-conditioning) system of EVs (electric vehicles)

International Nuclear Information System (INIS)

Chiu, Chien-Chin; Tsai, Nan-Chyuan; Lin, Chun-Chi

2014-01-01

This work is aimed to investigate the regulation problem for thermal comfortableness and propose control strategies for cabin environment of EVs (electric vehicles) by constructing a reduced-scale A/C (air-conditioning) system which mainly consists of two modules: ECB (environmental control box) and AHU (air-handling unit). Temperature and humidity in the ECB can be regulated by AHU via cooling, heating, mixing air streams and adjusting speed of fans. To synthesize the near-optimal controllers, the mathematical model for the system thermodynamics is developed by employing the equivalent lumped heat capacity approach, energy/mass conservation principle and the heat transfer theories. In addition, from the clustering pattern of system eigenvalues, the thermodynamics of the interested system can evidently be characterized by two-time-scale property. That is, the studied system can be decoupled into two subsystems, slow mode and fast mode, by singular perturbation technique. As to the optimal control strategies for EVs, by taking thermal comfortableness, humidity and energy consumption all into account, a series of optimal controllers is synthesized on the base of the order-reduced thermodynamic model. The feedback control loop for the experimental test rig is examined and realized by the aid of the control system development kit dSPACE DS1104 and the commercial software MATLAB/Simulink. To sum up, the intensive computer simulations and experimental results verify that the performance of the near-optimal order-reduced control law is almost as superior as that of standard LQR (Linear-Quadratic Regulator). - Highlights: • A reduced-scale test rig for A/C (air-conditioning) system to imitate the temperature/humidity of cabin in EV (electric vehicle) is constructed. • The non-linear thermodynamic model of A/C system can be decoupled by singular perturbation technique. • The temperature/humidity in cabin is regulated to the desired values by proposed optimal

Modeling and reliability analysis of three phase z-source AC-AC converter

Directory of Open Access Journals (Sweden)

Prasad Hanuman

2017-12-01

Full Text Available This paper presents the small signal modeling using the state space averaging technique and reliability analysis of a three-phase z-source ac-ac converter. By controlling the shoot-through duty ratio, it can operate in buck-boost mode and maintain desired output voltage during voltage sag and surge condition. It has faster dynamic response and higher efficiency as compared to the traditional voltage regulator. Small signal analysis derives different control transfer functions and this leads to design a suitable controller for a closed loop system during supply voltage variation. The closed loop system of the converter with a PID controller eliminates the transients in output voltage and provides steady state regulated output. The proposed model designed in the RT-LAB and executed in a field programming gate array (FPGA-based real-time digital simulator at a fixedtime step of 10 μs and a constant switching frequency of 10 kHz. The simulator was developed using very high speed integrated circuit hardware description language (VHDL, making it versatile and moveable. Hardware-in-the-loop (HIL simulation results are presented to justify the MATLAB simulation results during supply voltage variation of the three phase z-source ac-ac converter. The reliability analysis has been applied to the converter to find out the failure rate of its different components.

Control of Power Converters in AC Microgrids

DEFF Research Database (Denmark)

Rocabert, Joan; Luna, Alvaro; Blaabjerg, Frede

2012-01-01

The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability of the ele......The enabling of ac microgrids in distribution networks allows delivering distributed power and providing grid support services during regular operation of the grid, as well as powering isolated islands in case of faults and contingencies, thus increasing the performance and reliability...

Architecture and performance of neural networks for efficient A/C control in buildings

International Nuclear Information System (INIS)

Mahmoud, Mohamed A.; Ben-Nakhi, Abdullatif E.

2003-01-01

The feasibility of using neural networks (NNs) for optimizing air conditioning (AC) setback scheduling in public buildings was investigated. The main focus is on optimizing the network architecture in order to achieve best performance. To save energy, the temperature inside public buildings is allowed to rise after business hours by setting back the thermostat. The objective is to predict the time of the end of thermostat setback (EoS) such that the design temperature inside the building is restored in time for the start of business hours. State of the art building simulation software, ESP-r, was used to generate a database that covered the years 1995-1999. The software was used to calculate the EoS for two office buildings using the climate records in Kuwait. The EoS data for 1995 and 1996 were used for training and testing the NNs. The robustness of the trained NN was tested by applying them to a 'production' data set (1997-1999), which the networks have never 'seen' before. For each of the six different NN architectures evaluated, parametric studies were performed to determine the network parameters that best predict the EoS. External hourly temperature readings were used as network inputs, and the thermostat end of setback (EoS) is the output. The NN predictions were improved by developing a neural control scheme (NC). This scheme is based on using the temperature readings as they become available. For each NN architecture considered, six NNs were designed and trained for this purpose. The performance of the NN analysis was evaluated using a statistical indicator (the coefficient of multiple determination) and by statistical analysis of the error patterns, including ANOVA (analysis of variance). The results show that the NC, when used with a properly designed NN, is a powerful instrument for optimizing AC setback scheduling based only on external temperature records

Preliminary design of reactor coolant pump canned motor for AC600

International Nuclear Information System (INIS)

Deng Shaowen

1998-01-01

The reactor coolant pump canned motor of AC600 PWR is the kind of shielded motors with high moment of inertia, high reliability, high efficiency and nice starting performance. The author briefly presents the main feature, design criterion and technical requirements, preliminary design, computation results and analysis of performance of AC600 reactor coolant pump canned motor, and proposes some problems to be solved for study and design of AC600 reactor coolant pump canned motor

Research on a novel DDC-based capacity controller for the direct-expansion variable-air-volume A/C system

Energy Technology Data Exchange (ETDEWEB)

Chen Wu, E-mail: chenwu73@263.ne [School of Marine Engineering, Jimei University, Xiamen, Fujian Province 361021 (China); Deng Shiming [Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon (Hong Kong)

2010-01-15

A direct-expansion (DX) variable-air-volume (VAV) air-conditioning (A/C) system consists of a VAV air-distribution sub-system and a DX refrigeration plant. This paper reports in detail on a novel capacity controller developed for the DX VAV A/C system to regulate its compressor speed and hence its cooling capacity. The capacity controller consisted of both a numerical calculation algorithm (NCA), which was fundamentally based on the principle of energy balance using a number of real-time measured system's operating parameters, and a dead-band for decoupling the control actions from both the capacity controller and a conventional PI feedback controller for regulating the opening of an electronic expansion valve (EEV) in the refrigeration plant. To study the feasibility of the capacity controller, an experimental rig for the DX VAV A/C system having two conditioned spaces was built and experimental tests were carried out. The test results showed that using the capacity controller, the cooling capacity of the system's refrigeration plant can be accurately and continuously regulated and the supply air temperature well maintained at its desired value. The desirable independent zoning-control for space air temperatures can be successfully achieved by the DX VAV A/C system and the control performance for air temperatures in the conditioned space was highly satisfactory.

Research on a novel DDC-based capacity controller for the direct-expansion variable-air-volume A/C system

Energy Technology Data Exchange (ETDEWEB)

Chen, Wu [School of Marine Engineering, Jimei University, Xiamen, Fujian Province 361021 (China); Deng, Shiming [Department of Building Services Engineering, The Hong Kong Polytechnic University, Kowloon (China)

2010-01-15

A direct-expansion (DX) variable-air-volume (VAV) air-conditioning (A/C) system consists of a VAV air-distribution sub-system and a DX refrigeration plant. This paper reports in detail on a novel capacity controller developed for the DX VAV A/C system to regulate its compressor speed and hence its cooling capacity. The capacity controller consisted of both a numerical calculation algorithm (NCA), which was fundamentally based on the principle of energy balance using a number of real-time measured system's operating parameters, and a dead-band for decoupling the control actions from both the capacity controller and a conventional PI feedback controller for regulating the opening of an electronic expansion valve (EEV) in the refrigeration plant. To study the feasibility of the capacity controller, an experimental rig for the DX VAV A/C system having two conditioned spaces was built and experimental tests were carried out. The test results showed that using the capacity controller, the cooling capacity of the system's refrigeration plant can be accurately and continuously regulated and the supply air temperature well maintained at its desired value. The desirable independent zoning-control for space air temperatures can be successfully achieved by the DX VAV A/C system and the control performance for air temperatures in the conditioned space was highly satisfactory. (author)

Research on a novel DDC-based capacity controller for the direct-expansion variable-air-volume A/C system

International Nuclear Information System (INIS)

Chen Wu; Deng Shiming

2010-01-01

A direct-expansion (DX) variable-air-volume (VAV) air-conditioning (A/C) system consists of a VAV air-distribution sub-system and a DX refrigeration plant. This paper reports in detail on a novel capacity controller developed for the DX VAV A/C system to regulate its compressor speed and hence its cooling capacity. The capacity controller consisted of both a numerical calculation algorithm (NCA), which was fundamentally based on the principle of energy balance using a number of real-time measured system's operating parameters, and a dead-band for decoupling the control actions from both the capacity controller and a conventional PI feedback controller for regulating the opening of an electronic expansion valve (EEV) in the refrigeration plant. To study the feasibility of the capacity controller, an experimental rig for the DX VAV A/C system having two conditioned spaces was built and experimental tests were carried out. The test results showed that using the capacity controller, the cooling capacity of the system's refrigeration plant can be accurately and continuously regulated and the supply air temperature well maintained at its desired value. The desirable independent zoning-control for space air temperatures can be successfully achieved by the DX VAV A/C system and the control performance for air temperatures in the conditioned space was highly satisfactory.

Model Predictive Control of Power Converters for Robust and Fast Operation of AC Microgrids

DEFF Research Database (Denmark)

Dragicevic, Tomislav

2018-01-01

the load power at the same time. Those functionalities are conventionally achieved by hierarchical linear control loops. However, they have limited transient response and high sensitivity to parameter variations. This paper aims to mitigate these problems by firstly introducing an improvement of the FCS......This paper proposes the application of a finite control set model predictive control (FCS-MPC) strategy in standalone ac microgrids (MGs). AC MGs are usually built from two or more voltage source converters (VSCs) which can regulate the voltage at the point of common coupling, while sharing......-MPC strategy for a single VSC based on tracking of derivative of the voltage reference trajectory. Using only a single step prediction horizon, the proposed strategy exhibits low computational expense but provides steady state performance comparable to PWM, while its transient response and robustness...

Compensation methods applied in current control schemes for large AC drive systems

DEFF Research Database (Denmark)

Rus, D. C.; Preda, N. S.; Teodorescu, Remus

2012-01-01

The paper deals with modified PI current control structures for large AC drive systems which use surface mounted permanent magnet synchronous machines or squirrel-cage induction motors supplied with voltage source inverters. In order to reduce the power losses caused by high frequency switching...

Start Up Current Control of Buck-Boost Convertor-Fed Serial DC Motor

Directory of Open Access Journals (Sweden)

Yusuf SÖNMEZ

2009-02-01

Full Text Available Generally, DC motors are given preference for industrial applications such as electric locomotives, cranes, goods lifts. Because of they have high starting moment; they initially start with high current. This high start-up current must be decreased since it may damage windings of the motor and increases power consumption. It could be controlled by an appropriate driver system and controller. The nature of fuzzy logic control has adaptive characteristics that can achieve robust response to a system with uncertainty, parameter variation, and load disturbance. In this paper, fuzzy logic based control of start-up current of a Buck-Boost Converter fed serial DC motor is examined through computer simulation. In order to see the advantages of fuzzy logic control, classical PI control has applied to the same motor, under same circumstances and has been compared. C++ Builder software has been used for the simulation. According to the simulation results, plainly, fuzzy logic control has stronger responses than classical PI control and uses lower current at starting moment.

Large Signal Stabilization of Hybrid AC/DC Micro-Grids Using Nonlinear Robust Controller

Directory of Open Access Journals (Sweden)

Reza Pejmanfar

2017-12-01

Full Text Available This paper presents a robust nonlinear integrated controller to improve stability of hybrid AC/DC micro-grids under islanding mode. The proposed controller includes two independent controllers where each one is responsible to control one part of the system. First controller will improve the stability of input DC/DC converter. Using this controller, the voltage of DC bus is fully stabilized such that when a large disturbance occurs, its voltage will become constant without any significant dynamic. The necessity of DC bus regulation which has not been considered in previous studies, is imminent as it not only improves voltage stability of the micro-grid but also protects consumers which are directly connected to the DC bus, against voltage variations. Frequency stability of the micro-grid is provided by the second proposed controller which is applied to output DC/AC converter of the micro-grid. Adaptive method is used to make the controllers proposed in this paper, robust. Duty cycle of converters switches are adjusted such that voltage and frequency of the micro-grid are set on the desired value in minimum possible time under transient disturbances and uncertainty of the loads as well as micro-sources characteristics.

Containment and Consensus-based Distributed Coordination Control for Voltage Bound and Reactive Power Sharing in AC Microgrid

DEFF Research Database (Denmark)

Han, Renke; Meng, Lexuan; Ferrari-Trecate, Giancarlo

2017-01-01

This paper offers a highly flexible and reliable control strategy to achieve voltage bounded regulation and accurate reactive power sharing coordinately in AC Micro-Grids. A containment and consensus-based distributed coordination controller is proposed, by which each output voltage magnitude can...... be bounded within a reasonable range and the accurate reactive power sharing among distributed generators can be also achieved. Combined with the two proposed controllers and electrical part of the AC Micro-Grid, a small signal model is fully developed to analyze the sensitivity of different control...... parameters. The effectiveness of the proposed controller in case of load variation, communication failure, plug-and-play capability are verified by the experimental setup as an islanded Micro-Grid....

Operating experience of the automatic technological control system at the Kolsk NPP

International Nuclear Information System (INIS)

Volkov, A.P.; Ignatenko, E.I.; Kolomtsev, Yu.V.; Mel'nikov, E.F.; Trofimov, B.A.

1981-01-01

Briefly reviewed is operating experience of the automatic control systems of the kolsk NPP (KNPP) power units, where measuring technique of the neutron flux ''Iney'', ARM-4 power regulator, automatic turbine start-up system ATS are used. The main shortcomings of the technological process automatic control system (ACS) and ways of their removal are considered. It is noted that the KNPP ACS performs only limited start-up functions of the basic equipment and reactor power control as well as partially protection functions at instant loading drops and switch-off of the main circulating pump [ru

Vector control of three-phase AC machines system development in the practice

CERN Document Server

Quang, Nguyen Phung; Dittrich, J

2015-01-01

This book addresses the vector control of three-phase AC machines, in particular induction motors with squirrel-cage rotors (IM), permanent magnet synchronous motors (PMSM) and doubly-fed induction machines (DFIM), from a practical design and development perspective. The main focus is on the application of IM and PMSM in electrical drive systems, where field-orientated control has been successfully established in practice. It also discusses the use of grid-voltage oriented control of DFIMs in wind power plants. This second, enlarged edition includes new insights into flatness-based  nonlinear

A novel power control strategy of Modular Multi-level Converter in HVDC-AC hybrid transmission systems for passive networks

DEFF Research Database (Denmark)

Hu, Zhenda; Wu, Rui; Yang, Xiaodong

2014-01-01

With the development of High Voltage DC Transmission (HVDC) technology, there will be more and more HVDC-AC hybrid transmission system in the world. A basic challenge in HVDC-AC hybrid transmission systems is to optimize the power sharing between DC and AC lines, which become more severe when sup...... control strategy of Modular Multi-level Converter in VSC-HVDC, which can optimize converter output power according to passive network loading variation. Proposal method is studied with a case study of a VSC-HVDC AC hybrid project by PSCAD/EMTDC simulations....

Automatic start-up system of nuclear reactor based on sequence control technology

International Nuclear Information System (INIS)

Zhang Yao; Zhang Dafa; Peng Huaqing

2009-01-01

A conceptive design of an automatic start-up system based on the sequence control for the nuclear reactors is given in this paper, so as to solve the problems during the start-up process, such as the long operation time, low automatic control level and high accident rate. The start-up process and its requirements are analyzed in detail at first. Then,the principle, the architecture, the key technologies of the automatic start-up system of nuclear reactors are designed and discussed. With the designed system, the automatic start-up of the nuclear reactor can be realized,the work load of the operator can be reduced,and the safety and efficiency of the nuclear power plant during its start-up can be improved. (authors)

Innovative application of AC-voltammetry in the characterization of oxides nanolayers formed on metals, under the effect of AC-perturbations

Energy Technology Data Exchange (ETDEWEB)

Bueno, V.; Lazzari, L.; Ormellesse, M. [Politecnico di Milano, Milan (Italy). Dept. of Chemistry, Materials and Chemical Engineering; Spinelli, P. [Politecnico di Torino, Torino (Italy). Dept. of Materials Science and Chemical Engineering

2008-07-01

Stray AC-currents have been reported to cause many cases of unwanted corrosion on metallic structures. This study characterized the formation and stability of the surface oxide film formed on mild steel under the effect of AC voltage in a very basic environment. The response of the system to DC signals was examined, along with its reversibility to AC perturbations. SEM analysis was used to complement AC-Voltammetry. Reaction mechanisms responsible for the AC-corrosion were formulated. AC-Voltammetry involves the application of a controlled sinusoidal voltage onto a solid working electrode while it is being swept in a DC-voltage range, with the faradaic or capacitative components of the resulting AC-current being recorded. The innovative aspect is the application of AC-V to characterize its nano-surface while it is being affected by AC-signals. It was concluded that the AC-V can be useful for the study of redox processes occurring at the surface of a reactive electrode and for the application of a considerable AC perturbation to the electrode in a potentiostatically controlled way. According to the electrochemistry of the double layer, there are 3 main reactions in the NaOH 1M media that are not reversible to DC nor to AC perturbations in the range of cathodic protection of mild steel. When designing metallic systems susceptible to stray currents, the AC-V could quantify the final faradaic, resistive and capacitative responses. 6 refs., 1 fig.

Dynamics and Control During Start-Up of Energy Integrated Distillation Column

DEFF Research Database (Denmark)

of the inherent effects of process integration upon a start-up procedure. In particular the effect of energy recycle upon the possible start-up sequence, and the effect of using an actuator for control purposes, i.e. the heat pump, which in itself requires significant start-up time. The experimental application...

F2AC: A Lightweight, Fine-Grained, and Flexible Access Control Scheme for File Storage in Mobile Cloud Computing

Directory of Open Access Journals (Sweden)

Wei Ren

2016-01-01

Full Text Available Current file storage service models for cloud servers assume that users either belong to single layer with different privileges or cannot authorize privileges iteratively. Thus, the access control is not fine-grained and flexible. Besides, most access control methods at cloud servers mainly rely on computationally intensive cryptographic algorithms and, especially, may not be able to support highly dynamic ad hoc groups with addition and removal of group members. In this paper, we propose a scheme called F2AC, which is a lightweight, fine-grained, and flexible access control scheme for file storage in mobile cloud computing. F2AC can not only achieve iterative authorization, authentication with tailored policies, and access control for dynamically changing accessing groups, but also provide access privilege transition and revocation. A new access control model called directed tree with linked leaf model is proposed for further implementations in data structures and algorithms. The extensive analysis is given for justifying the soundness and completeness of F2AC.

Deletion of the AcMNPV core gene ac109 results in budded virions that are non-infectious

International Nuclear Information System (INIS)

Fang Minggang; Nie, Yingchao; Theilmann, David A.

2009-01-01

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac109 is a core gene and its function in the virus life cycle is unknown. To determine its role in the baculovirus life cycle, we used the AcMNPV bacmid system to generate an ac109 deletion virus (vAc 109KO ). Fluorescence and light microscopy showed that transfection of vAc 109KO results in a single-cell infection phenotype. Viral DNA replication is unaffected and the development of occlusion bodies in vAc 109KO -transfected cells evidenced progression to the very late phases of viral infection. Western blot and confocal immunofluorescence analysis showed that AC109 is expressed in the cytoplasm and nucleus throughout infection. In addition, AC109 is a structural protein as it was detected in both budded virus (BV) and occlusion derived virus in both the envelope and nucleocapsid fractions. Titration assays by qPCR and TCID 50 showed that vAc 109KO produced BV but the virions are non-infectious. The vAc 109KO BV were indistinguishable from the BV of repaired and wild type control viruses as determined by negative staining and electron microscopy.

A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

Directory of Open Access Journals (Sweden)

Yao Liu

2016-08-01

Full Text Available The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built based on photovoltaic (PV generator and ES; and coordinated control is proposed and developed to achieve power management in a decentralized manner. This control scheme contains three different droop strategies according to characteristics of PV and ES. First, the modified droop control is proposed for PV, which can take full utilization of renewable energy and avoid regulating output active power frequently. Second, to maintain the direct current (DC bus voltage stability, a novel droop control incorporating a constant power band is presented for DC-side ES. Third, a cascade droop control is designed for alternating current (AC-side ES. Thus, the ES lifetime is prolonged. Moreover, interlinking converters (ICs provide a bridge between AC/DC buses in a hybrid microgrid. The power control of IC is enabled when the AC- or DC-side suffer from active power demand shortage. In particular, if the AC microgrid does not satisfy the reactive power demand, IC then acts as a static synchronous compensator (STATCOM. The effectiveness of the proposed strategies is verified by simulations.

Automatic Control Systems (ACS for Generation and Sale of Electric Power Under Conditions of Industry-Sector Liberalization

Directory of Open Access Journals (Sweden)

Yu. S. Petrusha

2013-01-01

Full Text Available Possible risks pertaining to transition of electric-power industry to market relations have been considered in the paper. The paper presents an integrated ACS for generation and sale of electric power as an improvement of methodology for organizational and technical management. The given system is based on integration of operating Automatic Dispatch Control System (ADCS and developing Automatic Electricity Meter Reading System (AEMRS. The paper proposes to form an inter-branch sector of ACS PLC (Automatic Control System for Prolongation of Life Cycle users which is oriented on provision of development strategy.

AC Voltage Control of DC/DC Converters Based on Modular Multilevel Converters in Multi-Terminal High-Voltage Direct Current Transmission Systems

Directory of Open Access Journals (Sweden)

Rui Li

2016-12-01

Full Text Available The AC voltage control of a DC/DC converter based on the modular multilevel converter (MMC is considered under normal operation and during a local DC fault. By actively setting the AC voltage according to the two DC voltages of the DC/DC converter, the modulation index can be near unity, and the DC voltage is effectively utilized to output higher AC voltage. This significantly decreases submodule (SM capacitance and conduction losses of the DC/DC converter, yielding reduced capital cost, volume, and higher efficiency. Additionally, the AC voltage is limited in the controllable range of both the MMCs in the DC/DC converter; thus, over-modulation and uncontrolled currents are actively avoided. The AC voltage control of the DC/DC converter during local DC faults, i.e., standby operation, is also proposed, where only the MMC connected on the faulty cable is blocked, while the other MMC remains operational with zero AC voltage output. Thus, the capacitor voltages can be regulated at the rated value and the decrease of the SM capacitor voltages after the blocking of the DC/DC converter is avoided. Moreover, the fault can still be isolated as quickly as the conventional approach, where both MMCs are blocked and the DC/DC converter is not exposed to the risk of overcurrent. The proposed AC voltage control strategy is assessed in a three-terminal high-voltage direct current (HVDC system incorporating a DC/DC converter, and the simulation results confirm its feasibility.

Dynamics and Control During Start-up of Energy Integrated Distillation Column

DEFF Research Database (Denmark)

Eden, Mario Richard; Koggersbøl, Arne; Hallager, L.

2000-01-01

of the inherent effects of process integration upon a start-up procedure. In particular the effect of energy recycle upon the possible start-up sequence, and the effect of using an actuator f or control purposes, i.e. the heat pump, which in itself requires significant start-up time. The experimental application...

A Robust Suboptimal Current Control of an Interlink Converter for a Hybrid AC/DC Microgrid

Directory of Open Access Journals (Sweden)

Ismi Rosyiana Fitri

2018-05-01

Full Text Available A hybrid AC/DC microgrid is established with the aim of exploiting numerous types of renewable energy to meet the needs of different loads. The microgrid is decomposed by AC DC sub-grids which are connected by an interlink converter (IC. To maintain the security and reliability of the microgrid, an automatic controller for the interlink converter is needed. In this paper, we propose a Linear Matrix Inequalities (LMI-based current control method for the interlink converter. As the main features here, the interlink converter permits bidirectional power exchange between both sub-grids when a power–demand imbalance occurs in one sub-grid regardless of the converter system parameters. Simulations with various filter parameters are performed using the Matlab/Simulink software to validate the effectiveness of the proposed controller. In comparison with the existing Linear Quadratic Regulator (LQR-based current control, the proposed method is more robust against unknown system parameters and high load perturbation.

Three-Level AC-DC-AC Z-Source Converter Using Reduced Passive Component Count

DEFF Research Database (Denmark)

Loh, Poh Chiang; Gao, Feng; Tan, Pee-Chin

2009-01-01

This paper presents a three-level ac-dc-ac Z-source converter with output voltage buck-boost capability. The converter is implemented by connecting a low-cost front-end diode rectifier to a neutral-point-clamped inverter through a single X-shaped LC impedance network. The inverter is controlled...... to switch with a three-level output voltage, where the middle neutral potential is uniquely tapped from the star-point of a wye-connected capacitive filter placed before the front-end diode rectifier for input current filtering. Through careful control, the resulting converter can produce the correct volt...

Development of a hardware-based AC microgrid for AC stability assessment

Science.gov (United States)

Swanson, Robert R.

As more power electronic-based devices enable the development of high-bandwidth AC microgrids, the topic of microgrid power distribution stability has become of increased interest. Recently, researchers have proposed a relatively straightforward method to assess the stability of AC systems based upon the time-constants of sources, the net bus capacitance, and the rate limits of sources. In this research, a focus has been to develop a hardware test system to evaluate AC system stability. As a first step, a time domain model of a two converter microgrid was established in which a three phase inverter acts as a power source and an active rectifier serves as an adjustable constant power AC load. The constant power load can be utilized to create rapid power flow transients to the generating system. As a second step, the inverter and active rectifier were designed using a Smart Power Module IGBT for switching and an embedded microcontroller as a processor for algorithm implementation. The inverter and active rectifier were designed to operate simultaneously using a synchronization signal to ensure each respective local controller operates in a common reference frame. Finally, the physical system was created and initial testing performed to validate the hardware functionality as a variable amplitude and variable frequency AC system.

Towards controlled mutagenesis with transposons Ac and Tam3

Energy Technology Data Exchange (ETDEWEB)

Haring, M; Veken, J; Windrich, R; Kneppers, T; Rommens, C; Nijkamp, H J.J.; Hille, J [Department of Genetics, Free University, Amsterdam (Netherlands)

1990-01-01

Full text: The discovery of mobile genetic elements in plants has permitted the use of these transposons for insertional mutagenesis. This applies so far only to Zea mays and Antirrhinum majus, because other plant transposable elements have not been characterised so thoroughly at the genetic and the molecular level. To establish whether transposons (Ac from maize and Tam3 from Antirrhinum) remain mobile in heterologous hosts, either in somatic tissue or after meiosis, a phenotypic assay system for transposition was developed. The separation of the two transposition functions will allow controlled mutagenesis of plant genes. Our results indicate that both transposable elements remain active in heterologous hosts. (author)

Phase-insensitive detectors for ac resistance bridges with application to temperature control systems

International Nuclear Information System (INIS)

Duncan, M.G.

1977-01-01

A method of detecting AC resistance bridge error signals with low sensitivity to stray reactances is presented. The detector, which compares magnitudes of two bridge signals, can be used in a fast resistance temperature control to maintain constant resistance to better than 2 ppM at resistances down to 5 milliohms

Translation, modification and cellular distribution of two AC4 variants of African cassava mosaic virus in yeast and their pathogenic potential in plants

International Nuclear Information System (INIS)

Hipp, Katharina; Rau, Peter; Schäfer, Benjamin; Pfannstiel, Jens; Jeske, Holger

2016-01-01

Plant infecting geminiviruses encode a small (A)C4 protein within the open reading frame of the replication-initiator protein. In African cassava mosaic virus, two in-frame start codons may be used for the translation of a longer and a shorter AC4 variant. Both were fused to green fluorescent protein or glutathione-S-transferase genes and expressed in fission yeast. The longer variant accumulated in discrete spots in the cytoplasm, whereas the shorter variant localized to the plasma membrane. A similar expression pattern was found in plants. A myristoylation motif may promote a targeting of the shorter variant to the plasma membrane. Mass spectrometry analysis of the yeast-expressed shorter variant detected the corresponding myristoylation. The biological relevance of the second start codon was confirmed using mutated infectious clones. Whereas mutating the first start codon had no effect on the infectivity in Nicotiana benthamiana plants, the second start codon proved to be essential. -- Highlights: •The ACMV AC4 may be translated from one or the other in-frame start codon. •Both AC4 variants are translated in fission yeast. •The long AC4 protein localizes to the cytoplasm, the short to the plasma membrane. •The short variant is myristoylated in yeast and may promote membrane localization. •Only the shorter AC4 variant has an impact on viral infections in plants.

Translation, modification and cellular distribution of two AC4 variants of African cassava mosaic virus in yeast and their pathogenic potential in plants

Energy Technology Data Exchange (ETDEWEB)

Hipp, Katharina, E-mail: katharina.hipp@bio.uni-stuttgart.de [University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Rau, Peter; Schäfer, Benjamin [University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Pfannstiel, Jens [University of Hohenheim, Mass Spectrometry Core Facility, August-von-Hartmann-Straße 3, 70599 Stuttgart (Germany); Jeske, Holger [University of Stuttgart, Institute of Biomaterials and biomolecular Systems, Department of Molecular Biology and Plant Virology, Pfaffenwaldring 57, 70550 Stuttgart (Germany)

2016-11-15

Plant infecting geminiviruses encode a small (A)C4 protein within the open reading frame of the replication-initiator protein. In African cassava mosaic virus, two in-frame start codons may be used for the translation of a longer and a shorter AC4 variant. Both were fused to green fluorescent protein or glutathione-S-transferase genes and expressed in fission yeast. The longer variant accumulated in discrete spots in the cytoplasm, whereas the shorter variant localized to the plasma membrane. A similar expression pattern was found in plants. A myristoylation motif may promote a targeting of the shorter variant to the plasma membrane. Mass spectrometry analysis of the yeast-expressed shorter variant detected the corresponding myristoylation. The biological relevance of the second start codon was confirmed using mutated infectious clones. Whereas mutating the first start codon had no effect on the infectivity in Nicotiana benthamiana plants, the second start codon proved to be essential. -- Highlights: •The ACMV AC4 may be translated from one or the other in-frame start codon. •Both AC4 variants are translated in fission yeast. •The long AC4 protein localizes to the cytoplasm, the short to the plasma membrane. •The short variant is myristoylated in yeast and may promote membrane localization. •Only the shorter AC4 variant has an impact on viral infections in plants.

Road load simulator tests of the Gould phase 1 functional model silicon controlled rectifier ac motor controller for electric vehicles

Science.gov (United States)

Gourash, F.

1984-01-01

The test results for a functional model ac motor controller for electric vehicles and a three-phase induction motor which were dynamically tested on the Lewis Research Center road load simulator are presented. Results show that the controller has the capability to meet the SAE-J227a D cycle test schedule and to accelerate a 1576-kg (3456-lb) simulated vehicle to a cruise speed of 88.5 km/hr (55 mph). Combined motor controller efficiency is 72 percent and the power inverter efficiency alone is 89 percent for the cruise region of the D cycle. Steady state test results for motoring, regeneration, and thermal data obtained by operating the simulator as a conventional dynamometer are in agreement with the contractor's previously reported data. The regeneration test results indicate that a reduction in energy requirements for urban driving cycles is attainable with regenerative braking. Test results and data in this report serve as a data base for further development of ac motor controllers and propulsion systems for electric vehicles. The controller uses state-of-the-art silicon controlled rectifier (SCR) power semiconductors and microprocessor-based logic and control circuitry. The controller was developed by Gould Laboratories under a Lewis contract for the Department of Energy's Electric and Hybrid Vehicle program.

Road load simulator tests of the Gould phase 1 functional model silicon controlled rectifier ac motor controller for electric vehicles

Science.gov (United States)

Gourash, F.

1984-02-01

The test results for a functional model ac motor controller for electric vehicles and a three-phase induction motor which were dynamically tested on the Lewis Research Center road load simulator are presented. Results show that the controller has the capability to meet the SAE-J227a D cycle test schedule and to accelerate a 1576-kg (3456-lb) simulated vehicle to a cruise speed of 88.5 km/hr (55 mph). Combined motor controller efficiency is 72 percent and the power inverter efficiency alone is 89 percent for the cruise region of the D cycle. Steady state test results for motoring, regeneration, and thermal data obtained by operating the simulator as a conventional dynamometer are in agreement with the contractor's previously reported data. The regeneration test results indicate that a reduction in energy requirements for urban driving cycles is attainable with regenerative braking. Test results and data in this report serve as a data base for further development of ac motor controllers and propulsion systems for electric vehicles. The controller uses state-of-the-art silicon controlled rectifier (SCR) power semiconductors and microprocessor-based logic and control circuitry. The controller was developed by Gould Laboratories under a Lewis contract for the Department of Energy's Electric and Hybrid Vehicle program.

Stability Enhancement of Multi machine AC Systems by Synchronverter HVDC control

Directory of Open Access Journals (Sweden)

Raouia Aouini

2016-06-01

Full Text Available This paper investigates the impact of the Synchronverter based HVDC control on power system stability. The study considers multi machine power systems, with realistic parameters. A specific tuning method of the parameters of the regulators is used. The proposed control scheme is based on the sensitivity of the poles of the HVDC neighbor zone to the control parameters, and next, on their placement using residues. The transient stability of the HVDC neighbor zone is a priori taken into account at the design stage. The new tuning method is evaluated in comparison with the standard vector control via simulation tests. Extensive tests are performed using Matlab/Simulink implementation of the IEEE 9 bus/3 machines test system. The results prove the superiority of the proposed control to the classic vector control. The synchronverter control allows to improve not only the local performances of the HVDC link, but also the overall transient stability of the AC zone in which the HVDC is inserted. (where

Complex state variable- and disturbance observer-based current controllers for AC drives

DEFF Research Database (Denmark)

Dal, Mehmet; Teodorescu, Remus; Blaabjerg, Frede

2013-01-01

In vector-controlled AC drives, the design of current controller is usually based on a machine model defined in synchronous frame coordinate, where the drive performance may be degraded by both the variation of the machine parameters and the cross-coupling between the d- and q-axes components...... of the stator current. In order to improve the current control performance an alternative current control strategy was proposed previously aiming to avoid the undesired cross-coupling and non-linearities between the state variables. These effects are assumed as disturbances arisen in the closed-loop path...... of the parameter and the cross-coupling effect. Moreover, it provides a better performance, smooth and low noisy operation with respect to the complex variable controller....

MOEA based design of decentralized controllers for LFC of interconnected power systems with nonlinearities, AC-DC parallel tie-lines and SMES units

International Nuclear Information System (INIS)

Ganapathy, S.; Velusami, S.

2010-01-01

A new design of Multi-Objective Evolutionary Algorithm based decentralized controllers for load-frequency control of interconnected power systems with Governor Dead Band and Generation Rate Constraint nonlinearities, AC-DC parallel tie-lines and Superconducting Magnetic Energy Storage (SMES) units, is proposed in this paper. The HVDC link is used as system interconnection in parallel with AC tie-line to effectively damp the frequency oscillations of AC system while the SMES unit provides bulk energy storage and release, thereby achieving combined benefits. The proposed controller satisfies two main objectives, namely, minimum Integral Squared Error of the system output and maximum closed-loop stability of the system. Simulation studies are conducted on a two area interconnected power system with nonlinearities, AC-DC tie-lines and SMES units. Results indicate that the proposed controller improves the transient responses and guarantees the closed-loop stability of the overall system even in the presence of system nonlinearities and with parameter changes.

Vector control of three-phase AC/DC front-end converter

Indian Academy of Sciences (India)

Section 4 presents the simulation and experimental results of FEC. Section 5 discusses the problems associated with the starting process of ..... A 250-kVA vector-controlled FEC is simulated with MATLAB/SIMULINK. ..... Ghosh R 2007 Modelling, Analysis and Control of Single-phase and Three-phase PWM Rectifiers.

Advantages of Square-Root Extended Kalman Filter for Sensorless Control of AC Drives

Czech Academy of Sciences Publication Activity Database

Šmídl, Václav; Peroutka, Z.

2012-01-01

Roč. 59, č. 11 (2012), s. 4189-4196 ISSN 0278-0046 Institutional research plan: CEZ:AV0Z10750506 Institutional support: RVO:67985556 Keywords : Kalman filters * Mathematical model * AC motors Subject RIV: BC - Control Systems Theory Impact factor: 5.165, year: 2012 http://library.utia.cas.cz/separaty/2012/AS/smidl-0436868.pdf

A Control Strategy of DC Building Microgrid Connected to the Neighborhood and AC Power Network

Directory of Open Access Journals (Sweden)

Thi Thuong Huyen Ma

2017-05-01

Full Text Available Recently, the use of DC microgrid distribution system has become more attractive than traditional AC systems due to their energy efficiency and ability to easily integrate with renewable energy sources and batteries. This paper proposes a 500 V DC microgrid which consists of a 20 kWp photovoltaic panel, batteries, and DC loads. A hierarchical control strategy to ensure balance power of the DC microgrid and the maintenance of common DC bus voltage is presented. The capability of exchanging power energy of the microgrid with the power system of neighborhood buildings is also considered. Typical operation modes are simulated in the Matlab/simulink environment to confirm the good performance of the controllers and the efficiency of appropriately controlling the charge–discharge of the battery system. This research is expected to bring benefits to the design and operation of the system, such as reducing the capacity of batteries, increasing the self-supply of buildings, and decreasing the electricity demand from the AC grid.

Aging, Counterfeiting Configuration Control (AC3)

Science.gov (United States)

2010-01-31

Systems Intergrated Into AC3 CABS - Common As-Built System PRISM - Process Re-inventing Integration Systems for Manufacturing PDM - Product Data...looks forward to deploying the completed tool at Raytheon in a true production environment, for as much as we like the challenge associated with...performance of DoD systems. DoD systems are particularly susceptible to intrusion of counterfeit parts, especially during surge and extended production

Performance evaluation of a DC-AC inverter controlled with ZAD-FPIC

Directory of Open Access Journals (Sweden)

Fredy Edimer Hoyos Velasco

2018-01-01

Full Text Available Introduction: Power converters are used in microgrids to transfer power to the load with a regulated voltage. However, the DC-AC converters present distortions in the waveform that can be improved with the help of real-time controllers. Objective: Evaluate the response in alternating current of the buck converter controlled using ZAD-FPIC technique. Methodology: Based on the differential equations that describe the buck power converter, the ZAD and FPIC controllers are designed, simulations of the complete controlled system are made in Simulink of MATLAB, the system is implemented experimentally, and the controller is executed in real-time with the help of a DS1104 from dSPACE. In the end, several tests are carried out to check the effectiveness of the controller. Results: The results show that the controller allows good stability against different variations in the system and in the load. Conclusions: The ZAD-FPIC technique controls the variable and tracks changes in the waveform, magnitude, and frequency of the reference signal. The controller presents good stability to different tests, tracking the reference signal after each event.

Conventional P-ω/Q-V Droop Control in Highly Resistive Line of Low-Voltage Converter-Based AC Microgrid

Directory of Open Access Journals (Sweden)

Xiaochao Hou

2016-11-01

Full Text Available In low-voltage converter-based alternating current (AC microgrids with resistive distribution lines, the P-V droop with Q-f boost (VPD/FQB is the most common method for load sharing. However, it cannot achieve the active power sharing proportionally. To overcome this drawback, the conventional P-ω/Q-V droop control is adopted in the low-voltage AC microgrid. As a result, the active power sharing among the distributed generators (DGs is easily obtained without communication. More importantly, this study clears up the previous misunderstanding that conventional P-ω/Q-V droop control is only applicable to microgrids with highly inductive lines, and lays a foundation for the application of conventional droop control under different line impedances. Moreover, in order to guarantee the accurate reactive power sharing, a guide for designing Q-V droop gains is given, and virtual resistance is adopted to shape the desired output impedance. Finally, the effects of power sharing and transient response are verified through simulations and experiments in converter-based AC Microgrid.

Epidemiology and Management of Patients With Acute Coronary Syndromes in Contemporary Real-World Practice: Evolving Trends From the EYESHOT Study to the START-ANTIPLATELET Registry.

Science.gov (United States)

Calabrò, Paolo; Gragnano, Felice; di Maio, Marco; Patti, Giuseppe; Antonucci, Emilia; Cirillo, Plinio; Gresele, Paolo; Palareti, Gualtiero; Pengo, Vittorio; Pignatelli, Pasquale; Pennacchi, Mauro; Granatelli, Antonino; De Servi, Stefano; De Luca, Leonardo; Marcucci, Rossella

2018-01-01

The epidemiology and management of patients with acute coronary syndromes (ACSs) have evolved. We aimed to describe recent demographics and therapeutic changes in the Italian ACS population. We analyzed data from 2 multicenter consecutive Italian registries (the EYESHOT [EmploYEd antithrombotic therapies in patients with acute coronary Syndromes HOspitalised in iTalian cardiac care units] and START-ANTIPLATELET registries) enrolling patients with ACS between December 2013 and June 2016. An overall population of 3756 patients with ACS was enrolled: 2585 in the EYESHOT and 1171 in the START-ANTIPLATELET. Compared with the EYESHOT, patients in the START-ANTIPLATELET registry presented more frequently with ST-segment elevation myocardial infarction and were more often smokers and dyslipidemic (all P START-ANTIPLATELET (all P START-ANTIPLATELET compared with the EYESHOT. The START-ANTIPLATELET and EYESHOT registries provide consecutive snapshots in the contemporary management of patients with ACS in Italy, showing important changes in both demographic characteristics and treatment strategies.

Predictive Current Control of a 7-level AC-DC back-to-back Converter for Universal and Flexible Power Management System

DEFF Research Database (Denmark)

Bifaretti, Steffano; Zanchetta, Pericle; Iov, Florin

2008-01-01

The paper proposes a novel power conversion system for Universal and Flexible Power Management (UNIFLEX-PM) in Future Electricity Network. Its structure is based on a back-to-back three-phase AC-DC 7-level converter; each AC side is connected to a different PCC, representing the main grid and....../or various distributed generation systems. Effective and accurate power flow control is demonstrated through simulation in Matlab- Simulink environment on a model based on a two-port structure and using a Predictive Control technique. Control of different Power flow profiles has been successfully tested...

Control of parallel-connected bidirectional AC-DC converters in stationary frame for microgrid application

DEFF Research Database (Denmark)

Lu, Xiaonan; Guerrero, Josep M.; Teodorescu, Remus

2011-01-01

With the penetration of renewable energy in modern power system, microgrid has become a popular application worldwide. In this paper, parallel-connected bidirectional converters for AC and DC hybrid microgrid application are proposed as an efficient interface. To reach the goal of bidirectional...... power conversion, both rectifier and inverter modes are analyzed. In order to achieve high performance operation, hierarchical control system is accomplished. The control system is designed in stationary frame, with harmonic compensation in parallel and no coupled terms between axes. In this control...

AC Transmission Emulation Control Strategies for the BTB VSC HVDC System in the Metropolitan Area of Seoul

Directory of Open Access Journals (Sweden)

Sungyoon Song

2017-08-01

Full Text Available In the Korean power system, growing power loads have recently created the problems of voltage instability and fault current in the Seoul Capital Area (SCA. Accordingly, the back-to-back (BTB voltage source converter (VSC high-voltage direct-current (HVDC system is emerging to resolve such problems with grid segmentation. However, non-convergence problems occur in this metropolitan area, due to the large change of power flow in some contingencies. Therefore, this paper proposes two kinds of AC transmission emulation control (ATEC strategies to improve the metropolitan transient stability, and to resolve the non-convergence problem. The proposed ATEC strategies are able to mitigate possible overloading of adjacent AC transmission, and maintain power balance between metropolitan regions. The first ATEC strategy uses a monitoring system that permits the reverse power flow of AC transmission, and thus effectively improves the grid stability based on the power transfer equation. The second ATEC strategy emulates AC transmission with DC link capacitors in a permissible DC-link voltage range according to angle difference, and securely improves the gird stability, without requiring grid operator schedule decisions. This paper compares two kinds of ATEC schemes: it demonstrates the first ATEC strategy with specific fault scenario with PSS/E (Power Transmission System Planning Software, and evaluates the second ATEC strategy with internal controller performance with PSCAD/EMTDC (Power System Electromagnetic Transients Simulation Software.

Aragonite coating solutions (ACS) based on artificial seawater

Science.gov (United States)

Tas, A. Cuneyt

2015-03-01

Aragonite (CaCO3, calcium carbonate) is an abundant biomaterial of marine life. It is the dominant inorganic phase of coral reefs, mollusc bivalve shells and the stalactites or stalagmites of geological sediments. Inorganic and initially precipitate-free aragonite coating solutions (ACS) of pH 7.4 were developed in this study to deposit monolayers of aragonite spherules or ooids on biomaterial (e.g., UHMWPE, ultrahigh molecular weight polyethylene) surfaces soaked in ACS at 30 °C. The ACS solutions of this study have been developed for the surface engineering of synthetic biomaterials. The abiotic ACS solutions, enriched with calcium and bicarbonate ions at different concentrations, essentially mimicked the artificial seawater composition and started to deposit aragonite after a long (4 h) incubation period at the tropical sea surface temperature of 30 °C. While numerous techniques for the solution deposition of calcium hydroxyapatite (Ca10(PO4)6(OH)2), of low thermodynamic solubility, on synthetic biomaterials have been demonstrated, procedures related to the solution-based surface deposition of high solubility aragonite remained uncommon. Monolayers of aragonite ooids deposited at 30 °C on UHMWPE substrates soaked in organic-free ACS solutions were found to possess nano-structures similar to the mortar-and-brick-type botryoids observed in biogenic marine shells. Samples were characterized using SEM, XRD, FTIR, ICP-AES and contact angle goniometry.

Vector control of three-phase AC/DC front-end converter

Indian Academy of Sciences (India)

directional power flow capability. A design procedure for selection of control parameters is discussed. A simple algorithm for unit-vector generation is presented. Starting current transients are studied with particular emphasis on high-power ...

Wavelet-Fuzzy Speed Indirect Field Oriented Controller for Three-Phase AC Motor Drive

DEFF Research Database (Denmark)

Sanjeevikumar, Padmanaban; Daya, Febin; Blaabjerg, Frede

2016-01-01

Three-phase voltage source inverter driven induction motor are used in many medium- and high-power applications. Precision in speed of the motor play vital role, i.e. popular methods of direct/indirect field-oriented control (FOC) are applied. FOC is employed with proportional-integral (P...... wavelet transform and the fuzzy logic controller, to generate the scaled gains for the indirect FOC induction motor. Complete model of the proposed ac motor drive is developed with numerical simulation Matlab/Simulink software and tested under different working conditions. For experimental verification...

A single-phase embedded Z-source DC-AC inverter.

Science.gov (United States)

Kim, Se-Jin; Lim, Young-Cheol

2014-01-01

In the conventional DC-AC inverter consisting of two DC-DC converters with unipolar output capacitors, the output capacitor voltages of the DC-DC converters must be higher than the DC input voltage. To overcome this weakness, this paper proposes a single-phase DC-AC inverter consisting of two embedded Z-source converters with bipolar output capacitors. The proposed inverter is composed of two embedded Z-source converters with a common DC source and output AC load. Though the output capacitor voltages of the converters are relatively low compared to those of a conventional inverter, an equivalent level of AC output voltages can be obtained. Moreover, by controlling the output capacitor voltages asymmetrically, the AC output voltage of the proposed inverter can be higher than the DC input voltage. To verify the validity of the proposed inverter, experiments were performed with a DC source voltage of 38 V. By controlling the output capacitor voltages of the converters symmetrically or asymmetrically, the proposed inverter can produce sinusoidal AC output voltages. The experiments show that efficiencies of up to 95% and 97% can be achieved with the proposed inverter using symmetric and asymmetric control, respectively.

Flexible AC transmission systems: the state of the art

Energy Technology Data Exchange (ETDEWEB)

Edris, Abdel-Aty [Electric Power Research Inst., Palo Alto, CA (United States). Electric Systems Division

1994-12-31

Flexible AC transmission systems (FACTS) is a concept promoting the use of power electronic controllers to enhance the controllability and usable capacity of AC transmission. This paper presents the state of the art of FACTS and the status of the current projects for the application of the FACTS controllers in transmission systems. (author) 8 refs., 8 figs.

Autonomous Operation of Hybrid Microgrid With AC and DC Subgrids

DEFF Research Database (Denmark)

Chiang Loh, Poh; Li, Ding; Kang Chai, Yi

2013-01-01

sources distributed throughout the two types of subgrids, which is certainly tougher than previous efforts developed for only ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc sources, ac sources, and interlinking...... converters. Suitable control and normalization schemes are now developed for controlling them with the overall hybrid microgrid performance already verified in simulation and experiment.......This paper investigates on power-sharing issues of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac subgrids interconnected by power electronic interfaces. The main challenge here is to manage power flows among all...

The decay properties of the trapped magnetic field in HTS bulk superconducting actuator by AC controlled magnetic field

International Nuclear Information System (INIS)

Kim, S.B.; Uwani, Y.; Joo, J.H.; Kawamoto, R.; Jo, Y.S.

2011-01-01

The electric device applications of a high temperature superconducting (HTS) bulk magnet, having stable levitation and suspension properties according to their strong flux pinning force, have been proposed and developed. We have been investigating a three-dimensional (3-D) superconducting actuator using HTS bulks to develop a non-contract transportation device which moves freely in space. It is certain for our proposed 3-D superconducting actuator to be useful as a transporter used in a clean room where silicon wafers, which do not like mechanical contact and dust, are manufactured. The proposed actuator consists of the trapped HTS bulk as a mover and two-dimensionally arranged electromagnets as a stator. Up to now, the electromagnets consisted with iron core and copper coil were used as a stator, and each electromagnet was individually controlled using DC power supplies. In our previous work, the unstable movement characteristics of HTS bulk were observed under the DC operation, and the AC electromagnets driven with AC controlled current was proposed to solve these problems. In general, the trapped magnetic field in HTS bulk was decayed by a time-varying external magnetic field. Thus, it needs to optimize the shapes of AC electromagnets and operating patterns, the decay properties of the trapped magnetic field in the HTS bulk mover by the AC magnetic field should be cleared. In this paper, the influences of the frequency, the overall operating time, the strength of magnetization field and drive current against the decay of trapped magnetic field were experimentally studied using the fabricated AC electromagnets.

Chooz B1 start-up marked by total computer control

International Nuclear Information System (INIS)

Anon.

1995-01-01

The start-up of Chooz B1, the first of EdF's latest generation 1450 MWe N4 reactors, marks the first use in a nuclear power plant of a fully computerised control room. Working in partnership with EdF, Sema Group designed and supplied the advanced command and control system for this plant. (Author)

A Communication-Less Distributed Voltage Control Strategy for a Multi-Bus AC Islanded Microgrid

DEFF Research Database (Denmark)

Wang, Yanbo; Tan, Yongdong; Chen, Zhe

2014-01-01

This paper presents a communication-less distributed voltage control strategy for a multi-bus AC islanded microgrid. First, a Kalman Filter-based network voltage estimator is proposed to obtain voltage responses without communication links in the presence of load disturbances. Then, a voltage...... and reliability is improved for islanded microgrids due to communication-less operation. The simulations and experimental results are presented to validate the proposed distributed voltage control strategy....... optimal controller using MPC (Model Predictive Control) are developed to implement voltage optimal control. The contributions of this paper are demonstrated: (1) The proposed voltage estimator can dynamically obtain network voltage responses just through local voltage and current associated with each DG...

The design of control algorithm for automatic start-up model of HWRR

International Nuclear Information System (INIS)

Guo Wenqi

1990-01-01

The design of control algorithm for automatic start-up model of HWRR (Heavy Water Research Reactor), the calculation of μ value and the application of digital compensator are described. Finally The flow diagram of the automatic start-up and digital compensator program for HWRR are given

Application of AC servo motor on the in-core neutron flux instrumentation system

International Nuclear Information System (INIS)

Du Xiaoguang; Wang Mingtao

2010-01-01

The application of ac servo motor in the In-Core Neutron Flux Instrumentation System is described. The hardware component of ac servo motor control system is different from the dc motor control system. The effect of two control system on the instrumentation system is compared. The ac servo motor control system can improve the accuracy of the motion control, optimize the speed control and increase the reliability. (authors)

AC Initiation System.

Science.gov (United States)

An ac initiation system is described which uses three ac transmission signals interlocked for safety by frequency, phase, and power discrimination...The ac initiation system is pre-armed by the application of two ac signals have the proper phases, and activates a load when an ac power signal of the proper frequency and power level is applied. (Author)

Operation Cost Minimization of Droop-Controlled AC Microgrids Using Multiagent-Based Distributed Control

DEFF Research Database (Denmark)

Li, Chendan; Savaghebi, Mehdi; Guerrero, Josep M.

2016-01-01

on the power rating of the power converters. With various primary source for the distributed generator (DG), factors that are closely related to the operation cost, such as fuel cost of the generators and losses should be taken into account in order to improve the efficiency of the whole system. In this paper......, a multiagent-based distributed method is proposed to minimize the operation cost in AC microgrids. In the microgrid, each DG is acting as an agent which regulates the power individually using a novel power regulation method based on frequency scheduling. An optimal power command is obtained through carefully...... designed consensus algorithm by using sparse communication links only among neighbouring agents. Experimental results for different cases verified that the proposed control strategy can effectively reduce the operation cost....

Operation Cost Minimization of Droop-Controlled AC Microgrids Using Multiagent-Based Distributed Control

Directory of Open Access Journals (Sweden)

Chendan Li

2016-09-01

Full Text Available Recently, microgrids are attracting increasing research interest as promising technologies to integrate renewable energy resources into the distribution system. Although many works have been done on droop control applied to microgrids, they mainly focus on achieving proportional power sharing based on the power rating of the power converters. With various primary source for the distributed generator (DG, factors that are closely related to the operation cost, such as fuel cost of the generators and losses should be taken into account in order to improve the efficiency of the whole system. In this paper, a multiagent-based distributed method is proposed to minimize the operation cost in AC microgrids. In the microgrid, each DG is acting as an agent which regulates the power individually using a novel power regulation method based on frequency scheduling. An optimal power command is obtained through carefully designed consensus algorithm by using sparse communication links only among neighbouring agents. Experimental results for different cases verified that the proposed control strategy can effectively reduce the operation cost.

Coordinated Secondary Control for Balanced Discharge Rate of Energy Storage System in Islanded AC Microgrids

DEFF Research Database (Denmark)

Guan, Yajuan; Quintero, Juan Carlos Vasquez; Guerrero, Josep M.

2016-01-01

A coordinated secondary control approach based on an autonomous current-sharing control strategy for balancing the discharge rates of energy storage systems (ESSs) in islanded AC microgrids is proposed in this paper. The coordinated secondary controller can regulate the power outputs of distributed...... incidents and unintentional outages in DG units, but also aims to provide a fast transient response and an accurate output-current-sharing performance. A complete root locus analysis is given in order to achieve system stability and parameter sensitivity. Experimental results are presented to show...... the performance of the whole system and to verify the effectiveness of the proposed controller....

Research and simulation of the decoupling transformation in AC motor vector control

Science.gov (United States)

He, Jiaojiao; Zhao, Zhongjie; Liu, Ken; Zhang, Yongping; Yao, Tuozhong

2018-04-01

Permanent magnet synchronous motor (PMSM) is a nonlinear, strong coupling, multivariable complex object, and transformation decoupling can solve the coupling problem of permanent magnet synchronous motor. This paper gives a permanent magnet synchronous motor (PMSM) mathematical model, introduces the permanent magnet synchronous motor vector control coordinate transformation in the process of modal matrix inductance matrix transform through the matrix related knowledge of different coordinates of diagonalization, which makes the coupling between the independent, realize the control of motor current and excitation the torque current coupling separation, and derived the coordinate transformation matrix, the thought to solve the coupling problem of AC motor. Finally, in the Matlab/Simulink environment, through the establishment and combination between the PMSM ontology, coordinate conversion module, built the simulation model of permanent magnet synchronous motor vector control, introduces the model of each part, and analyzed the simulation results.

Study on ac losses of HTS coil carrying ac transport current

International Nuclear Information System (INIS)

Dai Taozhen; Tang Yuejin; Li Jingdong; Zhou Yusheng; Cheng Shijie; Pan Yuan

2005-01-01

Ac loss has an important influence on the thermal performances of HTS coil. It is necessary to quantify ac loss to ascertain its impact on coil stability and for sizing the coil refrigeration system. In this paper, we analyzed in detail the ac loss components, hysteresis loss, eddy loss and flux flow loss in the pancake HTS coil carrying ac transport current by finite element method. We also investigated the distribution of the ac losses in the coil to study the effects of magnetic field distribution on ac losses

Self-discharge of AC/AC electrochemical capacitors in salt aqueous electrolyte

International Nuclear Information System (INIS)

García-Cruz, L.; Ratajczak, P.; Iniesta, J.; Montiel, V.; Béguin, F.

2016-01-01

The self-discharge (SD) of electrochemical capacitors based on activated carbon electrodes (AC/AC capacitors) in aqueous lithium sulfate was examined after applying a three-hour cell potential hold at U i values from 1.0 to 1.6 V. The leakage current measured during the potentiostatic period as well as the amplitude of self-discharge increased with U i ; the cell potential drop was approximately doubled by 10 °C increase of temperature. The potential decay of both negative and positive electrodes was explored separately, by introducing a reference electrode and it was found that the negative electrode contributes essentially to the capacitor self-discharge. A diffusion-controlled mechanism was found at U i ≤ 1.4 V and U i ≤ 1.2 V for the positive and negative electrodes, respectively. At higher U i of 1.6 V, both electrodes display an activation-controlled mechanism due to water oxidation and subsequent carbon oxidation at the positive electrode and water or oxygen reduction at the negative electrode.

Storage evaporator for vehicles with start-stop technology; Speicherverdampfer fuer Fahrzeuge mit Start-Stopp-Funktion

Energy Technology Data Exchange (ETDEWEB)

Wawzyniak, Markus; Link, Joachim [Behr GmbH und Co. KG, Stuttgart (Germany)

2013-04-15

Today, the use of engine start-stop technology - a system designed to cut fuel consumption when the vehicle stops or, in future applications, when vehicles are in coasting or ''sailing'' mode - is gaining ground in more and more vehicle classes. Shutting off the internal combustion engine, though, detrimentally affects cabin air conditioning because the belt-driven A/C compressor is likewise deactivated, thus bringing the vapor compression process to a standstill. As a result, during extended stop periods and in warm weather vent temperatures and air humidity rapidly increase.

Conventional P-ω/Q-V Droop Control in Highly Resistive Line of Low-Voltage Converter-Based AC Microgrid

DEFF Research Database (Denmark)

Hou, Xiaochao; Sun, Yao; Yuan, Wenbin

2016-01-01

-ω/Q-V droop control is adopted in the low-voltage AC microgrid. As a result, the active power sharing among the distributed generators (DGs) is easily obtained without communication. More importantly, this study clears up the previous misunderstanding that conventional P-ω/Q-V droop control is only applicable...... to microgrids with highly inductive lines, and lays a foundation for the application of conventional droop control under different line impedances. Moreover, in order to guarantee the accurate reactive power sharing, a guide for designing Q-V droop gains is given, and virtual resistance is adopted to shape......In low-voltage converter-based alternating current (AC) microgrids with resistive distribution lines, the P-V droop with Q-f boost (VPD/FQB) is the most common method for load sharing. However, it cannot achieve the active power sharing proportionally. To overcome this drawback, the conventional P...

Single conversion audio amplifier and DC-AC converters with high performance and low complexity control scheme

DEFF Research Database (Denmark)

Poulsen, Søren; Andersen, Michael Andreas E.

2004-01-01

This paper proposes a novel control topology for a mains isolated single conversion audio amplifier and DC-AC converters. The topology is made for use in audio applications, and differs from prior art in terms of significantly reduced distortion as well as lower system complexity. The topology can...

Multiagent-Based Distributed State of Charge Balancing Control for Distributed Energy Storage Units in AC Microgrids

DEFF Research Database (Denmark)

Li, Chendan; Coelho, Ernane Antônio Alves; Dragicevic, Tomislav

2017-01-01

In this paper, a multiagent-based distributed control algorithm has been proposed to achieve state of charge (SoC) balance of distributed energy storage (DES) units in an ac microgrid. The proposal uses frequency scheduling instead of adaptive droop gain to regulate the active power. Each DES unit...

System and method for determining stator winding resistance in an AC motor

Science.gov (United States)

Lu, Bin [Kenosha, WI; Habetler, Thomas G [Snellville, GA; Zhang, Pinjia [Atlanta, GA; Theisen, Peter J [West Bend, WI

2011-05-31

A system and method for determining stator winding resistance in an AC motor is disclosed. The system includes a circuit having an input connectable to an AC source and an output connectable to an input terminal of an AC motor. The circuit includes at least one contactor and at least one switch to control current flow and terminal voltages in the AC motor. The system also includes a controller connected to the circuit and configured to modify a switching time of the at least one switch to create a DC component in an output of the system corresponding to an input to the AC motor and determine a stator winding resistance of the AC motor based on the injected DC component of the voltage and current.

Autonomous Operation of Hybrid Microgrid with AC and DC Sub-Grids

DEFF Research Database (Denmark)

Loh, Poh Chiang; Blaabjerg, Frede

2011-01-01

the power flow among all the sources distributed throughout the two types of sub-grids, which certainly is tougher than previous efforts developed for only either ac or dc microgrid. This wider scope of control has not yet been investigated, and would certainly rely on the coordinated operation of dc...... sources, ac sources and interlinking converters. Suitable control and normalization schemes are therefore developed for controlling them with results presented for showing the overall performance of the hybrid microgrid.......This paper investigates on the active and reactive power sharing of an autonomous hybrid microgrid. Unlike existing microgrids which are purely ac, the hybrid microgrid studied here comprises dc and ac sub-grids, interconnected by power electronic interfaces. The main challenge here is to manage...

Take Control of Getting Started with Dreamweaver

CERN Document Server

Keller, Arnie

2009-01-01

Learn fundamental Web design principles and become comfortable working in Dreamweaver's complex interface! Dreamweaver 8 is a great Web design tool for pros, but newcomers may be overwhelmed by its interface or want to know more about how to work creatively and intelligently in the program. Help is at hand in Take Control of Getting Started with Dreamweaver, which offers a detailed tutorial for making your first site in Dreamweaver. Author Arnie Keller, who teaches Web design at the University of Victoria, shows you how to style type the smart way with CSS, create a sophisticated page layout

Experimental implementation of a robust damped-oscillation control algorithm on a full-sized, two-degree-of-freedom, AC induction motor-driven crane

International Nuclear Information System (INIS)

Kress, R.L.; Jansen, J.F.; Noakes, M.W.

1994-01-01

When suspended payloads are moved with an overhead crane, pendulum like oscillations are naturally introduced. This presents a problem any time a crane is used, especially when expensive and/or delicate objects are moved, when moving in a cluttered an or hazardous environment, and when objects are to be placed in tight locations. Damped-oscillation control algorithms have been demonstrated over the past several years for laboratory-scale robotic systems on dc motor-driven overhead cranes. Most overhead cranes presently in use in industry are driven by ac induction motors; consequently, Oak Ridge National Laboratory has implemented damped-oscillation crane control on one of its existing facility ac induction motor-driven overhead cranes. The purpose of this test was to determine feasibility, to work out control and interfacing specifications, and to establish the capability of newly available ac motor control hardware with respect to use in damped-oscillation-controlled systems. Flux vector inverter drives are used to investigate their acceptability for damped-oscillation crane control. The purpose of this paper is to describe the experimental implementation of a control algorithm on a full-sized, two-degree-of-freedom, industrial crane; describe the experimental evaluation of the controller including robustness to payload length changes; explain the results of experiments designed to determine the hardware required for implementation of the control algorithms; and to provide a theoretical description of the controller

Negative effect of the 5'-untranslated leader sequence on Ac transposon promoter expression.

Science.gov (United States)

Scortecci, K C; Raina, R; Fedoroff, N V; Van Sluys, M A

1999-08-01

Transposable elements are used in heterologous plant hosts to clone genes by insertional mutagenesis. The Activator (Ac) transposable element has been cloned from maize, and introduced into a variety of plants. However, differences in regulation and transposition frequency have been observed between different host plants. The cause of this variability is still unknown. To better understand the activity of the Ac element, we analyzed the Ac promoter region and its 5'-untranslated leader sequence (5' UTL). Transient assays in tobacco NT1 suspension cells showed that the Ac promoter is a weak promoter and its activity was localized by deletion analyses. The data presented here indicate that the core of the Ac promoter is contained within 153 bp fragment upstream to transcription start sites. An important inhibitory effect (80%) due to the presence of the 5' UTL was found on the expression of LUC reporter gene. Here we demonstrate that the presence of the 5' UTL in the constructs reduces the expression driven by either strong or weak promoters.

Context based computational analysis and characterization of ARS consensus sequences (ACS of Saccharomyces cerevisiae genome

Directory of Open Access Journals (Sweden)

Vinod Kumar Singh

2016-09-01

Full Text Available Genome-wide experimental studies in Saccharomyces cerevisiae reveal that autonomous replicating sequence (ARS requires an essential consensus sequence (ACS for replication activity. Computational studies identified thousands of ACS like patterns in the genome. However, only a few hundreds of these sites act as replicating sites and the rest are considered as dormant or evolving sites. In a bid to understand the sequence makeup of replication sites, a content and context-based analysis was performed on a set of replicating ACS sequences that binds to origin-recognition complex (ORC denoted as ORC-ACS and non-replicating ACS sequences (nrACS, that are not bound by ORC. In this study, DNA properties such as base composition, correlation, sequence dependent thermodynamic and DNA structural profiles, and their positions have been considered for characterizing ORC-ACS and nrACS. Analysis reveals that ORC-ACS depict marked differences in nucleotide composition and context features in its vicinity compared to nrACS. Interestingly, an A-rich motif was also discovered in ORC-ACS sequences within its nucleosome-free region. Profound changes in the conformational features, such as DNA helical twist, inclination angle and stacking energy between ORC-ACS and nrACS were observed. Distribution of ACS motifs in the non-coding segments points to the locations of ORC-ACS which are found far away from the adjacent gene start position compared to nrACS thereby enabling an accessible environment for ORC-proteins. Our attempt is novel in considering the contextual view of ACS and its flanking region along with nucleosome positioning in the S. cerevisiae genome and may be useful for any computational prediction scheme.

Study on AC loss measurements of HTS power cable for standardizing

Science.gov (United States)

Mukoyama, Shinichi; Amemiya, Naoyuki; Watanabe, Kazuo; Iijima, Yasuhiro; Mido, Nobuhiro; Masuda, Takao; Morimura, Toshiya; Oya, Masayoshi; Nakano, Tetsutaro; Yamamoto, Kiyoshi

2017-09-01

High-temperature superconducting power cables (HTS cables) have been developed for more than 20 years. In addition of the cable developments, the test methods of the HTS cables have been discussed and proposed in many laboratories and companies. Recently the test methods of the HTS cables is required to standardize and to common in the world. CIGRE made the working group (B1-31) for the discussion of the test methods of the HTS cables as a power cable, and published the recommendation of the test method. Additionally, IEC TC20 submitted the New Work Item Proposal (NP) based on the recommendation of CIGRE this year, IEC TC20 and IEC TC90 started the standardization work on Testing of HTS AC cables. However, the individual test method that used to measure a performance of HTS cables hasn’t been established as world’s common methods. The AC loss is one of the most important properties to disseminate low loss and economical efficient HTS cables in the world. We regard to establish the method of the AC loss measurements in rational and in high accuracy. Japan is at a leading position in the AC loss study, because Japanese researchers have studied on the AC loss technically and scientifically, and also developed the effective technologies for the AC loss reduction. The JP domestic commission of TC90 made a working team to discussion the methods of the AC loss measurements for aiming an international standard finally. This paper reports about the AC loss measurement of two type of the HTS conductors, such as a HTS conductor without a HTS shield and a HTS conductor with a HTS shield. The AC loss measurement method is suggested by the electrical method..

Performance of AC/graphite capacitors at high weight ratios of AC/graphite

Energy Technology Data Exchange (ETDEWEB)

Wang, Hongyu [IM and T Ltd., Advanced Research Center, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan); Yoshio, Masaki [Advanced Research Center, Department of Applied Chemistry, Saga University, 1341 Yoga-machi, Saga 840-0047 (Japan)

2008-03-01

The effect of negative to positive electrode materials' weight ratio on the electrochemical performance of both activated carbon (AC)/AC and AC/graphite capacitors has been investigated, especially in the terms of capacity and cycle-ability. The limited capacity charge mode has been proposed to improve the cycle performance of AC/graphite capacitors at high weight ratios of AC/graphite. (author)

Wind-powered asynchronous AC/DC/AC converter system. [for electric power supply regulation

Science.gov (United States)

Reitan, D. K.

1973-01-01

Two asynchronous ac/dc/ac systems are modelled that utilize wind power to drive a variable or constant hertz alternator. The first system employs a high power 60-hertz inverter tie to the large backup supply of the power company to either supplement them from wind energy, storage, or from a combination of both at a preset desired current; rectifier and inverter are identical and operate in either mode depending on the silicon control rectifier firing angle. The second system employs the same rectification but from a 60-hertz alternator arrangement; it provides mainly dc output, some sinusoidal 60-hertz from the wind bus and some high harmonic content 60-hertz from an 800-watt inverter.

Impurity control and its impact upon start-up and transformer recharging in NET

International Nuclear Information System (INIS)

Harrison, M.F.A.

1985-01-01

Control of the release of impurities and their subsequent ingress and exhaust from tokamak plasmas has been the subject of intensive studies aimed at both the prediction of reactor burn condition and the interpretation of results from present experiments. Control concepts which are specific to current-initiation, current ramp-up and RF heating during start-up of a reactor such as NET have to date received little attention, according to the author. This paper presents an inductive start-up scenario which is typical of those presently being considered for NET. Shown are plasma configurations during start-up. Particularly significant issues are the advantages of forming the divertor configuration at the earliest practicable stage and the problems expected due to contamination of the limiter with divertor material

Aragonite coating solutions (ACS) based on artificial seawater

International Nuclear Information System (INIS)

Tas, A. Cuneyt

2015-01-01

Graphical abstract: - Highlights: • Developed completely inorganic solutions for the deposition of monolayers of aragonite spherules (or ooids). • Solutions mimicked the artificial seawater. • Biomimetic crystallization was performed at the tropical sea surface temperature of 30 °C. - Abstract: Aragonite (CaCO 3 , calcium carbonate) is an abundant biomaterial of marine life. It is the dominant inorganic phase of coral reefs, mollusc bivalve shells and the stalactites or stalagmites of geological sediments. Inorganic and initially precipitate-free aragonite coating solutions (ACS) of pH 7.4 were developed in this study to deposit monolayers of aragonite spherules or ooids on biomaterial (e.g., UHMWPE, ultrahigh molecular weight polyethylene) surfaces soaked in ACS at 30 °C. The ACS solutions of this study have been developed for the surface engineering of synthetic biomaterials. The abiotic ACS solutions, enriched with calcium and bicarbonate ions at different concentrations, essentially mimicked the artificial seawater composition and started to deposit aragonite after a long (4 h) incubation period at the tropical sea surface temperature of 30 °C. While numerous techniques for the solution deposition of calcium hydroxyapatite (Ca 10 (PO 4 ) 6 (OH) 2 ), of low thermodynamic solubility, on synthetic biomaterials have been demonstrated, procedures related to the solution-based surface deposition of high solubility aragonite remained uncommon. Monolayers of aragonite ooids deposited at 30 °C on UHMWPE substrates soaked in organic-free ACS solutions were found to possess nano-structures similar to the mortar-and-brick-type botryoids observed in biogenic marine shells. Samples were characterized using SEM, XRD, FTIR, ICP-AES and contact angle goniometry

Aragonite coating solutions (ACS) based on artificial seawater

Energy Technology Data Exchange (ETDEWEB)

Tas, A. Cuneyt, E-mail: c_tas@hotmail.com

2015-03-01

Graphical abstract: - Highlights: • Developed completely inorganic solutions for the deposition of monolayers of aragonite spherules (or ooids). • Solutions mimicked the artificial seawater. • Biomimetic crystallization was performed at the tropical sea surface temperature of 30 °C. - Abstract: Aragonite (CaCO{sub 3}, calcium carbonate) is an abundant biomaterial of marine life. It is the dominant inorganic phase of coral reefs, mollusc bivalve shells and the stalactites or stalagmites of geological sediments. Inorganic and initially precipitate-free aragonite coating solutions (ACS) of pH 7.4 were developed in this study to deposit monolayers of aragonite spherules or ooids on biomaterial (e.g., UHMWPE, ultrahigh molecular weight polyethylene) surfaces soaked in ACS at 30 °C. The ACS solutions of this study have been developed for the surface engineering of synthetic biomaterials. The abiotic ACS solutions, enriched with calcium and bicarbonate ions at different concentrations, essentially mimicked the artificial seawater composition and started to deposit aragonite after a long (4 h) incubation period at the tropical sea surface temperature of 30 °C. While numerous techniques for the solution deposition of calcium hydroxyapatite (Ca{sub 10}(PO{sub 4}){sub 6}(OH){sub 2}), of low thermodynamic solubility, on synthetic biomaterials have been demonstrated, procedures related to the solution-based surface deposition of high solubility aragonite remained uncommon. Monolayers of aragonite ooids deposited at 30 °C on UHMWPE substrates soaked in organic-free ACS solutions were found to possess nano-structures similar to the mortar-and-brick-type botryoids observed in biogenic marine shells. Samples were characterized using SEM, XRD, FTIR, ICP-AES and contact angle goniometry.

Small-Signal Analysis of Single-Phase and Three-phase DC/AC and AC/DC PWM Converters with the Frequency-Shift Technique

DEFF Research Database (Denmark)

Blaabjerg, Frede; Aquila, A. Dell’; Liserre, Marco

2004-01-01

of dc/dc converters via a 50 Hz frequency-shift. The input admittance is calculated and measured for two study examples (a three-phase active rectifier and a single-phase photovoltaic inverter). These examples show that the purpose of a well designed controller for grid-connected converters......A systematic approach to study dc/ac and ac/dc converters without the use of synchronous transformation is proposed. The use of a frequency-shift technique allows a straightforward analysis of single-phase and three-phase systems. The study of dc/ac and of ac/dc converters is reported to the study...... is to minimize the input admittance in order to make the grid converter more robust to grid disturbance....

Expression Study of LeGAPDH, LeACO1, LeACS1A, and LeACS2 in Tomato Fruit (Solanum lycopersicum

Directory of Open Access Journals (Sweden)

Pijar Riza Anugerah

2015-10-01

Full Text Available Tomato is a climacteric fruit, which is characterized by ripening-related increase of respiration and elevated ethylene synthesis. Ethylene is the key hormone in ripening process of climacteric fruits. The objective of this research is to study the expression of three ethylene synthesis genes: LeACO1, LeACS1A, LeACS2, and a housekeeping gene LeGAPDH in ripening tomato fruit. Specific primers have been designed to amplify complementary DNA fragment of LeGAPDH (143 bp, LeACO1 (240 bp, LeACS1A (169 bp, and LeACS2 (148 bp using polymerase chain reaction. Nucleotide BLAST results of the complementary DNA fragments show high similarity with LeGAPDH (NM_001247874.1, LeACO1 (NM_001247095.1, LeACS1A (NM_001246993.1, LeACS2 (NM_001247249.1, respectively. Expression study showed that LeACO1, LeACS1A, LeACS2, and LeGAPDH genes were expressed in ripening tomato fruit. Isolation methods, reference sequences, and primers used in this study can be used in future experiments to study expression of genes responsible for ethylene synthesis using quantitative polymerase chain reaction and to design better strategy for controlling fruit ripening in agroindustry.

Frequency Control Strategy for Black Starts via PMSG-Based Wind Power Generation

Directory of Open Access Journals (Sweden)

Yi Tang

2017-03-01

Full Text Available The use of wind power generation (WPG as a source for black starts will significantly enhance the resiliency of power systems and shorten their recovery time from blackouts. Given that frequency stability is the most serious issue during the initial recovery period, virtual inertia control can enable wind turbines to provide frequency support to an external system. In this study, a general procedure of WPG participating in black starts is presented, and the key issues are discussed. The adaptability of existing virtual inertia control strategies is analyzed, and improvement work is performed. A new coordinated frequency control strategy is proposed based on the presented improvement work. A local power network with a permanent-magnet synchronous generator (PMSG-based wind farm is modeled and used to verify the effectiveness of the strategy.

A THREE-PHASE BOOST DC-AC CONVERTER

African Journals Online (AJOL)

dc-ac converter (inverter) based on the dc-dc boost converters. ... Sliding mode controllers are designed to perform a robust control for the ... Computer simulations and spectral analysis demon- ... the conventional three-phase buck inverter,.

Black start research of the wind and storage system based on the dual master-slave control

Science.gov (United States)

Leng, Xue; Shen, Li; Hu, Tian; Liu, Li

2018-02-01

Black start is the key to solving the problem of large-scale power failure, while the introduction of new renewable clean energy as a black start power supply was a new hotspot. Based on the dual master-slave control strategy, the wind and storage system was taken as the black start reliable power, energy storage and wind combined to ensure the stability of the micorgrid systems, to realize the black start. In order to obtain the capacity ratio of the storage in the small system based on the dual master-slave control strategy, and the black start constraint condition of the wind and storage combined system, obtain the key points of black start of wind storage combined system, but also provide reference and guidance for the subsequent large-scale wind and storage combined system in black start projects.

A new on-chip all-digital three-phase full-bridge dc/ac power inverter with feedforward and frequency control techniques.

Science.gov (United States)

Chen, Jiann-Jong; Kung, Che-Min

2010-09-01

The communication speed between components is far from satisfactory. To achieve high speed, simple control system configuration, and low cost, a new on-chip all-digital three-phase dc/ac power inverter using feedforward and frequency control techniques is proposed. The controller of the proposed power inverter, called the shift register, consists of six-stage D-latch flip-flops with a goal of achieving low-power consumption and area efficiency. Variable frequency is achieved by controlling the clocks of the shift register. One advantage regarding the data signal (D) and the common clock (CK) is that, regardless of the phase difference between the two, all of the D-latch flip-flops are capable of delaying data by one CK period. To ensure stability, the frequency of CK must be six times higher than that of D. The operation frequency of the proposed power inverter ranges from 10 Hz to 2 MHz, and the maximum output loading current is 0.8 A. The prototype of the proposed circuit has been fabricated with TSMC 0.35 μm 2P4M CMOS processes. The total chip area is 2.333 x 1.698 mm2. The three-phase dc/ac power inverter is applicable in uninterrupted power supplies, cold cathode fluorescent lamps, and motors, because of its ability to convert the dc supply voltage into the three-phase ac power sources.

Multi-Agent-Based Controller for Voltage Enhancement in AC/DC Hybrid Microgrid Using Energy Storages

Directory of Open Access Journals (Sweden)

Ahmadali Khatibzadeh

2017-02-01

Full Text Available Development of renewable energies and DC loads have led microgrids toward the creation of DC networks. The predictions show that the hybrid microgrids will be used widely in the future. This article has studied the voltage stability in the presence of sources of energy storage in AC/DC hybrid networks. However, because the different dynamics of hybrid networks applying centralized and distributed controllers will be faced with different problems, in this study, a multi-agent control for the microgrid has been used. A new structure referred to here as an event-driven microgrid control management (EDMCM has been developed to control the microgrid. This method increases response speed and accuracy of decision making. Hybrid Network Simulation results confirm the validity of the developed model.

Neural network based PWM AC chopper fed induction motor drive

Directory of Open Access Journals (Sweden)

Venkatesan Jamuna

2009-01-01

Full Text Available In this paper, a new Simulink model for a neural network controlled PWM AC chopper fed single phase induction motor is proposed. Closed loop speed control is achieved using a neural network controller. To maintain a constant fluid flow with a variation in pressure head, drives like fan and pump are operated with closed loop speed control. The need to improve the quality and reliability of the drive circuit has increased because of the growing demand for improving the performance of motor drives. With the increased availability of MOSFET's and IGBT's, PWM converters can be used efficiently in low and medium power applications. From the simulation studies, it is seen that the PWM AC chopper has a better harmonic spectrum and lesser copper loss than the Phase controlled AC chopper. It is observed that the drive system with the proposed model produces better dynamic performance, reduced overshoot and fast transient response. .

Three-Phase Multistage System (DC-AC-DC-AC for Connecting Solar Cells to the Grid

Directory of Open Access Journals (Sweden)

Mahmudreza Changizian

2017-11-01

Full Text Available Inverter systems that feed electrical power from photovoltaic (PV system into the grid must convert the direct current of the PV array into the alternating current of the grid. In many applications, it is important for a converter to be lightweight, highly reliable, input/output isolated, flexible and operable in a boost mode. These features can be achieved by using a High-Frequency inverter which involves an isolated DC-DC stage and DC-AC section, which provides AC output. This paper proposes a new three phase topology, based on multi stage converter and PV system in order to use in medium and high power applications. The Perturb and Observe (P&O method is used for maximum power point tracking (MPPT control of PV array. The switching control signals for three-phase inverter are provided by hysteresis control method. Also, the comparison between the proposed topology and traditional structures has been conducted and finally the simulation researches are performed in a closed-loop control system by MATLAB/Simulink software to verify the operation of the proposed structure. The results represent better performance of the introduced system over traditional topologies.

FUEL SUPPLY IN ACCUMULATOR DIESEL SYSTEMS WITH ELECTRONIC CONTROL AT STARTING REGIME

Directory of Open Access Journals (Sweden)

G. M. Kuharenok

2009-01-01

Full Text Available The paper contains review and analysis of fuel supply process in accumulator diesel systems with electronic control at starting regime. The necessity has been shown to  develop and use programs of mathematic simulation pertaining to fuel supply processes with the purpose to decrease number of bench tests and time period required for a fuel system adaptation. The paper cites results of practical investigations on starting engines  equipped with the mentioned-above systems.

OPTIMAL CONTROL OF AUTOCLAVE START MODE IN THE PRODUCTION OF NITRIC ACID

OpenAIRE

Ладієва, Леся Ростиславівна; Ширма, А. В.

2015-01-01

The algorithm of optimal control of autoclave start mode in the production of nitric acid is proposed. By optimality criterion is selected minimum time-autoclave at preset mode with the restriction on the concentration of nitric acid. End time start mode is entered on the terminal part of the cost function. The method of penalties and a gradient procedure is used to solve the problem. The applied algorithm is allowed to bring an autoclave at a given technological regime.Keywords: production o...

Distributed Primary and Secondary Power Sharing in a Droop-Controlled LVDC Microgrid with Merged AC and DC Characteristics

DEFF Research Database (Denmark)

Peyghami, Saeed; Mokhtari, Hossein; Loh, Poh Chiang

2018-01-01

In an ac microgrid, a common frequency exists for coordinating active power sharing among droop-controlled sources. A common frequency is absent in a dc microgrid, leaving only the dc source voltages for coordinating active power sharing. That causes sharing error and poorer voltage regulation in...

Peltier ac calorimeter

OpenAIRE

Jung, D. H.; Moon, I. K.; Jeong, Y. H.

2001-01-01

A new ac calorimeter, utilizing the Peltier effect of a thermocouple junction as an ac power source, is described. This Peltier ac calorimeter allows to measure the absolute value of heat capacity of small solid samples with sub-milligrams of mass. The calorimeter can also be used as a dynamic one with a dynamic range of several decades at low frequencies.

Digital model for harmonic interactions in AC/DC/AC systems

Energy Technology Data Exchange (ETDEWEB)

Guarini, A P; Rangel, R D; Pilotto, L A.S.; Pinto, R J; Passos, Junior, R [Centro de Pesquisas de Energia Eletrica (CEPEL), Rio de Janeiro, RJ (Brazil)

1994-12-31

The main purpose of this paper is to present a model for calculation of HVdc converter harmonics taking into account the influence of the harmonic interactions between the ac systems in dc link transmissions. The ideas and methodologies used in the model development take into account the dc current ripple and ac voltage distortion in the ac systems. The theory of switching functions is applied to contemplate for the frequency conversions between the ac and dc sides, in an iterative process. It is possible then to obtain, even in balanced situations, non-characteristic harmonics that are produced by frequencies originated in the other terminal, which can be significant in a strongly coupled system, such as back-to-back configuration. (author) 9 refs., 3 figs.

A Case Study of Wind-PV-Thermal-Bundled AC/DC Power Transmission from a Weak AC Network

Science.gov (United States)

Xiao, H. W.; Du, W. J.; Wang, H. F.; Song, Y. T.; Wang, Q.; Ding, J.; Chen, D. Z.; Wei, W.

2017-05-01

Wind power generation and photovoltaic (PV) power generation bundled with the support by conventional thermal generation enables the generation controllable and more suitable for being sent over to remote load centre which are beneficial for the stability of weak sending end systems. Meanwhile, HVDC for long-distance power transmission is of many significant technique advantages. Hence the effects of wind-PV-thermal-bundled power transmission by AC/DC on power system have become an actively pursued research subject recently. Firstly, this paper introduces the technical merits and difficulties of wind-photovoltaic-thermal bundled power transmission by AC/DC systems in terms of meeting the requirement of large-scale renewable power transmission. Secondly, a system model which contains a weak wind-PV-thermal-bundled sending end system and a receiving end system in together with a parallel AC/DC interconnection transmission system is established. Finally, the significant impacts of several factors which includes the power transmission ratio between the DC and AC line, the distance between the sending end system and receiving end system, the penetration rate of wind power and the sending end system structure on system stability are studied.

Device for the nuclear reactor automatic start-up and power control

International Nuclear Information System (INIS)

Nikiforov, B.N.; Volkov, A.V.; Ogon'kov, A.I.

1978-01-01

A description and flowsheet of a reactor start-up and power-control automatic device containing no nonlinear elements with a relay characteristic are presented. The device consists of two independent channels for measuring the physical power and time (period) constant of the reactor. Requirements for the device are considered, based on the condition of a minimum permissible number of a servomechanism operations due to fluctuations of an input signal which appear because of the statistical nature of processes taking place in the reactor. It is noted that the threshold amplifier used in the device allows a considerable decrease of the reactor start-up time

Design and Evaluation for Target Indicated Torque Based Engine Starting Control Strategy in a High Pressure Common Rail Diesel Engine

Directory of Open Access Journals (Sweden)

Xuedong Lin

2016-01-01

Full Text Available The diesel engine power demand of the start condition can be separated into two parts including resistance overcoming and acceleration realization for the reason that there is no power output during the starting process. The present paper mainly focuses on the fuel injection quantity control based on the engine power demand especially the acceleration demand for the resistance force is fixed for a specific engine, and the starting acceleration velocity is set as a target curve so that the acceleration process can also be fixed. The feasibility of the start control strategy proposed in this paper was verified by a comparison of the traditional starting control with a constant fuel quantity, and starting performance of the target acceleration based control shows predominance to the constant quantity control. And then the comparison between various starting acceleration processes, which was realized by the settings of acceleration curve slope factor, was conducted and results showed that the acceleration processes with higher slope factors perform better.

Flyback CCM inverter for AC module applications: iterative learning control and convergence analysis

Science.gov (United States)

Lee, Sung-Ho; Kim, Minsung

2017-12-01

This paper presents an iterative learning controller (ILC) for an interleaved flyback inverter operating in continuous conduction mode (CCM). The flyback CCM inverter features small output ripple current, high efficiency, and low cost, and hence it is well suited for photovoltaic power applications. However, it exhibits the non-minimum phase behaviour, because its transfer function from control duty to output current has the right-half-plane (RHP) zero. Moreover, the flyback CCM inverter suffers from the time-varying grid voltage disturbance. Thus, conventional control scheme results in inaccurate output tracking. To overcome these problems, the ILC is first developed and applied to the flyback inverter operating in CCM. The ILC makes use of both predictive and current learning terms which help the system output to converge to the reference trajectory. We take into account the nonlinear averaged model and use it to construct the proposed controller. It is proven that the system output globally converges to the reference trajectory in the absence of state disturbances, output noises, or initial state errors. Numerical simulations are performed to validate the proposed control scheme, and experiments using 400-W AC module prototype are carried out to demonstrate its practical feasibility.

ACS Zero Point Verification

Science.gov (United States)

Dolphin, Andrew

2005-07-01

The uncertainties in the photometric zero points create a fundamental limit to the accuracy of photometry. The current state of the ACS calibration is surprisingly poor, with zero point uncertainties of 0.03 magnitudes. The reason for this is that the ACS calibrations are based primarily on semi-emprical synthetic zero points and observations of fields too crowded for accurate ground-based photometry. I propose to remedy this problem by obtaining ACS images of the omega Cen standard field with all nine broadband ACS/WFC filters. This will permit the direct determination of the ACS zero points by comparison with excellent ground-based photometry, and should reduce their uncertainties to less than 0.01 magnitudes. A second benefit is that it will facilitate the comparison of the WFPC2 and ACS photometric systems, which will be important as WFPC2 is phased out and ACS becomes HST's primary imager. Finally, three of the filters will be repeated from my Cycle 12 observations, allowing for a measurement of any change in sensitivity.

Improved Design Methods for Robust Single- and Three-Phase ac-dc-ac Power Converters

DEFF Research Database (Denmark)

Qin, Zian

. The approaches for improving their performance, in terms of the voltage stress, efficiency, power density, cost, loss distribution, and temperature, will be studied. The structure of the thesis is as follows, Chapter 1 presents the introduction and motivation of the whole project as well as the background...... becomes a emerging challenge. Accordingly, installation of sustainable power generators like wind turbines and solar panels has experienced a large increase during the last decades. Meanwhile, power electronics converters, as interfaces in electrical system, are delivering approximately 80 % electricity...... back-to-back, and meanwhile improve the harmonics, control flexibility, and thermal distribution between the switches. Afterwards, active power decoupling methods for single-phase inverters or rectifiers that are similar to the single-phase ac-dc-ac converter, are studied in Chapter 4...

STARTing Again: What Happens After START I Expires?

International Nuclear Information System (INIS)

Mladineo, Stephen V.; Durbin, Karyn R.; Eastman, Christina M.

2007-01-01

The Strategic Arms Reduction Treaty (START I), a seminal arms control agreement that substantially reduced the levels of deployed strategic nuclear arms in the United States and Russia, will expire in December 2009. At this time, it is unclear what - if anything - will replace it. While the treaty remains relevant, more than a simple extension is appropriate. Instead the authors advocate for a successor regime that builds on the START I legacy but does not rely on the traditional tools of arms control. This paper examines the strategic context in which a successor regime would be developed and proposes several recommendations for future action

Multiagent based Distributed Control for Operation Cost Minimization of Droop Controlled AC Microgrid Using Incremental Cost Consensus

DEFF Research Database (Denmark)

Li, Chendan; Firoozabadi, Mehdi Savaghebi; Quintero, Juan Carlos Vasquez

2015-01-01

sharing based on the power rating. With various types of distributed generator (DG) units in the system, factors that closely related to the operation cost, such as fuel cost and efficiencies of the generator should be taken into account in order to improve the efficiency of the whole system....... In this paper, a multiagent based distributed method is proposed to minimize operation cost of the AC microgrid. Each DG is acting as an agent which regulates the power individually using proposed frequency scheduling method. Optimal power command is obtained through carefully designed consensus algorithm...... with only light communication between neighboring agents. Case studies verified that the proposed control strategy can effectively reduce the operation cost....

Start-up and control method and apparatus for resonant free piston Stirling engine

Science.gov (United States)

Walsh, Michael M.

1984-01-01

A resonant free-piston Stirling engine having a new and improved start-up and control method and system. A displacer linear electrodynamic machine is provided having an armature secured to and movable with the displacer and having a stator supported by the Stirling engine housing in juxtaposition to the armature. A control excitation circuit is provided for electrically exciting the displacer linear electrodynamic machine with electrical excitation signals having substantially the same frequency as the desired frequency of operation of the Stirling engine. The excitation control circuit is designed so that it selectively and controllably causes the displacer electrodynamic machine to function either as a generator load to extract power from the displacer or the control circuit selectively can be operated to cause the displacer electrodynamic machine to operate as an electric drive motor to apply additional input power to the displacer in addition to the thermodynamic power feedback to the displacer whereby the displacer linear electrodynamic machine also is used in the electric drive motor mode as a means for initially starting the resonant free-piston Stirling engine.

ac propulsion system for an electric vehicle

Science.gov (United States)

Geppert, S.

1980-01-01

It is pointed out that dc drives will be the logical choice for current production electric vehicles (EV). However, by the mid-80's, there is a good chance that the price and reliability of suitable high-power semiconductors will allow for a competitive ac system. The driving force behind the ac approach is the induction motor, which has specific advantages relative to a dc shunt or series traction motor. These advantages would be an important factor in the case of a vehicle for which low maintenance characteristics are of primary importance. A description of an EV ac propulsion system is provided, taking into account the logic controller, the inverter, the motor, and a two-speed transmission-differential-axle assembly. The main barrier to the employment of the considered propulsion system in EV is not any technical problem, but inverter transistor cost.

DC Voltage Droop Control Structures and its Impact on the Interaction Modes in Interconnected AC-HVDC Systems

DEFF Research Database (Denmark)

Thams, Florian; Chatzivasileiadis, Spyros; Eriksson, Robert

2017-01-01

Different dc voltage droop control structures for future multi-terminal HVDC systems have been proposed in literature. This paper contributes to the evaluation of those structures by an analysis of their impact on the coupling of the interconnected subsystems. In particular, the modes...... of the systems are classified in different subsets according to the participation of the various subsystems. Those subsets are then evaluated qualitatively and quantitatively indicating which impact the choice of the droop control structure has on the degree of coupling between the connected ac and dc systems...

Effect of gear shift and engine start losses on control strategies for hybrid electric vehicles

NARCIS (Netherlands)

Ngo, V.; Hofman, T.; Steinbuch, M.; Serrarens, A.

2012-01-01

In this paper, energetic loss models in the events of shifting gear and starting engine in a parallel Hybrid Electric Vehicle equipped with an Automated Manual Transmission (AMT) will be introduced. The optimal control algorithm for the start-stop, power split and gear shift problem based on Dynamic

Low Offset AC Correlator.

Science.gov (United States)

This patent describes a low offset AC correlator avoids DC offset and low frequency noise by frequency operating the correlation signal so that low...noise, low level AC amplification can be substituted for DC amplification. Subsequently, the high level AC signal is demodulated to a DC level. (Author)

DBSSP - A computer program for simulation of controlled circulation boiler and natural circulation boiler start up behavior

International Nuclear Information System (INIS)

Li Bin; Chen Tingkuan; Yang Dong

2005-01-01

In this paper, a computer program, Drum Boiler Start-up Simulation Program (DBSSP), is developed for simulating the start up behavior of controlled circulation and natural circulation boilers. The mathematical model developed here is based on the first principles of mass, energy and momentum conservations. In the boiler model, heat transfer in the waterwall, the superheater, the reheater and the economizer is simulated by the distributing parameter method, while heat transfer in the drum and the downcomer is simulated by lumped parameter analysis. The program can provide detailed flow and thermodynamic characteristics of the boiler components. The development of this program is based only on design data, so it can be used for any subcritical, controlled or natural circulation boiler. The simulation results were compared with experimental measurements, and good agreements between them were found. This program is expected to be useful for predicting the characteristics and the performance of controlled circulation and natural circulation boilers during the start up process. It also can be used to optimize a start up system for minimum start up time

AC power supply systems

International Nuclear Information System (INIS)

Law, H.

1987-01-01

An ac power supply system includes a rectifier fed by a normal ac supply, and an inverter connected to the rectifier by a dc link, the inverter being effective to invert the dc output of the receiver at a required frequency to provide an ac output. A dc backup power supply of lower voltage than the normal dc output of the rectifier is connected across the dc link such that the ac output of the rectifier is derived from the backup supply if the voltage of the output of the inverter falls below that of the backup supply. The dc backup power may be derived from a backup ac supply. Use in pumping coolant in nuclear reactor is envisaged. (author)

Control of VSC-HVDC in offshore AC islands with wind power plants: Comparison of two alternatives

DEFF Research Database (Denmark)

Zeni, Lorenzo; Hesselbæk, Bo; Sørensen, Poul Ejnar

2015-01-01

The subject of this paper is the control of offshore AC collection and export networks behind a voltage source converter based high voltage direct current transmission system. The inertia-less nature of such grids makes the control of voltages and power flows potentially more flexible......, but at the same time more prone to instabilities. Focus in this paper is on a voltage source converter based high voltage direct current connected wind power plant. Two state-of-art controllers for the offshore high voltage direct current converter station are compared, both at no-load and when wind turbine...... converters are producing power and controlled with usual vector current control. Sensitivity analyses help identify critical factors influencing stability. The influence of lumping the wind power plant into one converter is assessed by comparison with the full model. The conclusions identify the preferred...

A phase IIa randomised clinical study of GNbAC1, a humanised monoclonal antibody against the envelope protein of multiple sclerosis-associated endogenous retrovirus in multiple sclerosis patients.

Science.gov (United States)

Derfuss, Tobias; Curtin, François; Guebelin, Claudia; Bridel, Claire; Rasenack, Maria; Matthey, Alain; Du Pasquier, Renaud; Schluep, Myriam; Desmeules, Jules; Lang, Alois B; Perron, Hervé; Faucard, Raphael; Porchet, Hervé; Hartung, Hans-Peter; Kappos, Ludwig; Lalive, Patrice H

2015-06-01

GNbAC1 is an immunoglobulin (IgG4) humanised monoclonal antibody against multiple sclerosis-associated retrovirus (MSRV)-Env, a protein of endogenous retroviral origin, expressed in multiple sclerosis (MS) lesions, which is pro-inflammatory and inhibits oligodendrocyte precursor cell differentiation. This is a randomised, double-blind placebo-controlled dose-escalation study followed by a six-month open-label phase to test GNbAC1 in MS patients. The primary objective was to assess GNbAC1 safety in MS patients, and the other objectives were pharmacokinetic and pharmacodynamic assessments. Ten MS patients were randomised into two cohorts to receive a single intravenous infusion of GNbAC1/placebo at doses of 2 or 6 mg/kg. Then all patients received five infusions of GNbAC1 at 2 or 6 mg/kg at four-week intervals in an open-label setting. Safety, brain magnetic resonance imaging (MRI), pharmacokinetics, immunogenicity, cytokines and MSRV RNA expression were studied. All patients completed the study. GNbAC1 was well tolerated in all patients. GNbAC1 pharmacokinetics is dose-linear with mean elimination half-life of 27-37 d. Anti-GNbAC1 antibodies were not detected. Cytokine analysis did not indicate an adverse effect. MSRV-transcripts showed a decline after the start of treatment. Nine patients had stable brain lesions at MRI. The safety, pharmacokinetic profile, and pharmacodynamic responses to GNbAC1 are favourable in MS patients over a six-month treatment period. © The Author(s) 2014.

Demonstration of AC and DC charge control for the LISA test masses

Science.gov (United States)

Olatunde, Taiwo Janet

2018-01-01

Taiwo Olatunde, Stephen Apple, Andrew Chilton, Samantha Parry, Peter Wass, Guido Mueller, John W. Conklin The residual test mass acceleration in LISA must be below 3 fm/s2/√Hz at all frequencies between 0.1 and 3 mHz. Test mass charge coupled with stray electrical potentials and external electromagnetic fields is a well-known source of acceleration noise. LISA Pathfinder uses Hg lamps emitting mostly around 254 nm to discharge the test masses via photoemission, but a future LISA mission launched around 2030 will likely replace the lamps with newer UV LEDs with lower mass, better power efficiency, smaller size and higher bandwidth. This presentation will discuss charge control demonstrated on the torsion pendulum in AC and DC modes at the University of Florida using latest generation UV LEDs producing light at 240 nm with energy above the work function of pure Au. Initial results of Au quantum efficiency measurements (number of emitted electrons per incident photons) which is critical for bi-polar charge control will also be presented.

Combined operation of AC and DC distribution system with distributed generation units

International Nuclear Information System (INIS)

Noroozian, R.; Abedi, M.; Gharehpetian, G.

2010-01-01

This paper presents a DC distribution system which has been supplied by external AC systems as well as local DG units in order to demonstrate an overall solution to power quality issue. In this paper, the proposed operation method is demonstrated by simulation of power transfer between external AC systems, DG units, AC and DC loads. The power flow control in DC distribution system has been achieved by network converters and DG converters. Also, the mathematical model of the network, DG and load converters are obtained by using the average technique, which allows converter systems accurately simulated and control strategies for this converters is achieved. A suitable control strategy for network converters has been proposed that involves DC voltage droop regulator and novel instantaneous power regulation scheme. Also, a novel control technique has been proposed for DG converters. In this paper, a novel control system based on stationary and synchronously rotating reference frame has been proposed for load converters for supplying AC loads connected to the DC bus by balanced voltages. The several case studies have been studied based on proposed methods. The simulation results show that DC distribution systems including DG units can improve the power quality at the point of common coupling (PCC) in the power distribution system or industrial power system. (authors)

The impact of dry-land sprint start training on the short track speed skating start.

Science.gov (United States)

Haug, William B; Drinkwater, Eric J; Cicero, Nicholas J; Barthell, J Anthony; Chapman, Dale W

2017-05-05

This investigation sought to determine the effects of dry-land sprint start training on short track speed skating (STSS) start performance. Nine highly trained short track athletes completed a control period of normal STSS training followed by a four-week training intervention. Before and after the control and intervention periods, athletes performed three electronically timed dry-land and on-ice 14.43 m maximal sprint start efforts. The intervention consisted of two sprint sessions per week consisting of nine electronically timed 14.43 m dry-land sprint starts in addition to normal STSS training. The control period resulted in no substantial change in on-ice start performance (Mean Δ: -0.01 s, 95% Confidence Limits (CL): -0.08 to 0.05 s; Effect Size (ES): -0.05; Trivial) however, a small change was observed in dry-land start performance (Mean Δ: -0.07 s, 95% CL: -0.13 to -0.02 s; ES: -0.49). Following brief specific dry-land sprint start training a small improvement was observed in both on-ice (Mean Δ: -0.07 s, 95% CL: -0.13 to -0.01 s; ES: -0.33) and dry-land (Mean Δ: -0.04 s, 95% CL: -0.09 to 0.00 s; ES: -0.29) start performance. This investigation suggests STSS start performance can be improved through a brief dry-land sprint start training program.

Total synthesis and allelopathic activity of cytosporones A-C

Energy Technology Data Exchange (ETDEWEB)

Zamberlam, Charles E.M.; Meza, Alisson; Lima, Denis P. de; Beatriz, Adilson [Centro de Ciencias Exatas e Tecnologia, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS (Brazil); Leite, Carla Braga; Marques, Maria Rita [Centro de Ciencias Biologicas e da Saude, Universidade Federal de Mato Grosso do Sul, Campo Grande, MS (Brazil)

2012-07-01

The search for efficient, environmentally friendly herbicides has been the focus of numerous studies on the organic synthesis of compounds isolated from natural sources. Cytosporones, which are phenolic lipids isolated from fungi, exhibit noteworthy biological properties. This paper reports the preparation of cytosporones A-C from the same starting material through a short synthetic route, with good yields. All compounds were tested for allelopathic activity on lettuce (Lactuca sativa L) seeds. Cytosporone A and its methylated precursor showed remarkable allelopathic activity, inhibiting seed germination and plantule growth. (author)

Total synthesis and allelopathic activity of cytosporones A-C

International Nuclear Information System (INIS)

Zamberlam, Charles E.M.; Meza, Alisson; Lima, Denis P. de; Beatriz, Adilson; Leite, Carla Braga; Marques, Maria Rita

2012-01-01

The search for efficient, environmentally friendly herbicides has been the focus of numerous studies on the organic synthesis of compounds isolated from natural sources. Cytosporones, which are phenolic lipids isolated from fungi, exhibit noteworthy biological properties. This paper reports the preparation of cytosporones A-C from the same starting material through a short synthetic route, with good yields. All compounds were tested for allelopathic activity on lettuce (Lactuca sativa L) seeds. Cytosporone A and its methylated precursor showed remarkable allelopathic activity, inhibiting seed germination and plantule growth. (author)

AC/DC current ratio in a current superimposition variable flux reluctance machine

Science.gov (United States)

Kohara, Akira; Hirata, Katsuhiro; Niguchi, Noboru; Takahara, Kazuaki

2018-05-01

We have proposed a current superimposition variable flux reluctance machine for traction motors. The torque-speed characteristics of this machine can be controlled by increasing or decreasing the DC current. In this paper, we discuss an AC/DC current ratio in the current superimposition variable flux reluctance machine. The structure and control method are described, and the characteristics are computed using FEA in several AC/DC ratios.

ACS Photometric Zero Point Verification

Science.gov (United States)

Dolphin, Andrew

2003-07-01

The uncertainties in the photometric zero points create a fundamental limit to the accuracy of photometry. The current state of the ACS calibration is surprisingly poor, with zero point uncertainties of 0.03 magnitudes in the Johnson filters. The reason for this is that ACS observations of excellent ground-based standard fields, such as the omega Cen field used for WFPC2 calibrations, have not been obtained. Instead, the ACS photometric calibrations are based primarily on semi-emprical synthetic zero points and observations of fields too crowded for accurate ground-based photometry. I propose to remedy this problem by obtaining ACS broadband images of the omega Cen standard field with both the WFC and HRC. This will permit the direct determination of the ACS transformations, and is expected to double the accuracy to which the ACS zero points are known. A second benefit is that it will facilitate the comparison of the WFPC2 and ACS photometric systems, which will be important as WFPC2 is phased out and ACS becomes HST's primary imager.

Calculation method for control rod dropping time in reactor

International Nuclear Information System (INIS)

Nogami, Takeki; Kato, Yoshifumi; Ishino, Jun-ichi; Doi, Isamu.

1996-01-01

If a control rod starts dropping, the dropping speed is rapidly increased, then settled substantially constant, rapidly decreased when it reaches a dash pot. A second detection signal generated by removing an AC component from a first detection signal is differentiated twice. The time when the maximum value among the twice differentiated values is generated is determined as a time when the control rods starts dropping. The time when minimum value among the twice differentiated values is generated is determined as a time when the control rod reaches the dash pot of the reactor. The measuring time within a range from the time when the control rod starts dropping to the time when the control rod reaches the dash pot of the reactor is determined. As a result, processing for the calculation of the dropping start time and dash pot reaching time of the control rod can be automatized. Further, it is suffice to conduct differentiation twice till the reaching time, which can facilitate the processing thereby enabling to determine a reliable time range. (N.H.)

The Prevessin Control Room during LEP's start up in 1989.

CERN Multimedia

1989-01-01

The Prévessin Control Room saw its first momentous event when the 400 GeV beam for the SPS was commissioned in the presence of Project Leader John Adams. It was also here that the first proton-antiproton collisions were observed, in 1981. Eight years later, in 1989, operators and directors alike jumped for joy at the announcement of the first electron-positron collisions at the start up of LEP, the biggest accelerator in the world.

Field Performance of Bt Eggplants (Solanum melongena L. in the Philippines: Cry1Ac Expression and Control of the Eggplant Fruit and Shoot Borer (Leucinodes orbonalis Guenee.

Directory of Open Access Journals (Sweden)

Desiree M Hautea

Full Text Available Plants expressing Cry proteins from the bacterium, Bacillus thuringiensis (Bt, have become a major tactic for controlling insect pests in maize and cotton globally. However, there are few Bt vegetable crops. Eggplant (Solanum melongena is a popular vegetable grown throughout Asia that is heavily treated with insecticides to control the eggplant fruit and shoot borer, Leucinodes orbonalis (EFSB. Herein we provide the first publicly available data on field performance in Asia of eggplant engineered to produce the Cry1Ac protein. Replicated field trials with five Bt eggplant open-pollinated (OP lines from transformation event EE-1 and their non-Bt comparators were conducted over three cropping seasons in the Philippines from 2010-2012. Field trials documented levels of Cry1Ac protein expressed in plants and evaluated their efficacy against the primary target pest, EFSB. Cry1Ac concentrations ranged from 0.75-24.7 ppm dry weight with the highest in the terminal leaves (or shoots and the lowest in the roots. Cry1Ac levels significantly increased from the vegetative to the reproductive stage. Bt eggplant lines demonstrated excellent control of EFSB. Pairwise analysis of means detected highly significant differences between Bt eggplant lines and their non-Bt comparators for all field efficacy parameters tested. Bt eggplant lines demonstrated high levels of control of EFSB shoot damage (98.6-100% and fruit damage (98.1-99.7% and reduced EFSB larval infestation (95.8-99.3% under the most severe pest pressure during trial 2. Moths that emerged from larvae collected from Bt plants in the field and reared in their Bt eggplant hosts did not produce viable eggs or offspring. These results demonstrate that Bt eggplant lines containing Cry1Ac event EE-1 provide outstanding control of EFSB and can dramatically reduce the need for conventional insecticides.

Objectives and status of development of AC600

International Nuclear Information System (INIS)

Zhao Chengkun

1997-01-01

AC600 is a medium power capability nuclear power station of next generation, which is developed based on world nuclear power improving tendency, requirements of custom with considering China situation and technical foundation. Its main technical characteristics are as following: advanced core and passive safety system, double loop standard design and international popular equipment. Meanwhile, it a simplification of present system, using advanced control room and pattern construction thus developed the operation reliability of nuclear power station, lower construction and operating cost. In order to accelerate the development of next generation advanced reactor, cooperating with Westinghouse Electric Corporation, the joint economic technical research has been established. Based on AC600, the CAP600 is developed on further improving safety and reliability, economical and electric network adoption of AC600

FLUIDIC AC AMPLIFIERS.

Science.gov (United States)

Several fluidic tuned AC Amplifiers were designed and tested. Interstage tuning and feedback designs are considered. Good results were obtained...corresponding Q’s as high as 12. Element designs and test results of one, two, and three stage amplifiers are presented. AC Modulated Carrier Systems

Design of a data-driven predictive controller for start-up process of AMT vehicles.

Science.gov (United States)

Lu, Xiaohui; Chen, Hong; Wang, Ping; Gao, Bingzhao

2011-12-01

In this paper, a data-driven predictive controller is designed for the start-up process of vehicles with automated manual transmissions (AMTs). It is obtained directly from the input-output data of a driveline simulation model constructed by the commercial software AMESim. In order to obtain offset-free control for the reference input, the predictor equation is gained with incremental inputs and outputs. Because of the physical characteristics, the input and output constraints are considered explicitly in the problem formulation. The contradictory requirements of less friction losses and less driveline shock are included in the objective function. The designed controller is tested under nominal conditions and changed conditions. The simulation results show that, during the start-up process, the AMT clutch with the proposed controller works very well, and the process meets the control objectives: fast clutch lockup time, small friction losses, and the preservation of driver comfort, i.e., smooth acceleration of the vehicle. At the same time, the closed-loop system has the ability to reject uncertainties, such as the vehicle mass and road grade.

78 FR 49318 - Availability of Draft Advisory Circular (AC) 90-106A and AC 20-167A

Science.gov (United States)

2013-08-13

...] Availability of Draft Advisory Circular (AC) 90-106A and AC 20- 167A AGENCY: Federal Aviation Administration... of draft Advisory Circular (AC) 90-106A, Enhanced Flight Vision Systems and draft AC 20- 167A... Federal holidays. FOR FURTHER INFORMATION CONTACT: For technical questions concerning draft AC 90-106A...

The Challenge for Arms Control Verification in the Post-New START World

Energy Technology Data Exchange (ETDEWEB)

Wuest, C R

2012-05-24

Nuclear weapon arms control treaty verification is a key aspect of any agreement between signatories to establish that the terms and conditions spelled out in the treaty are being met. Historically, arms control negotiations have focused more on the rules and protocols for reducing the numbers of warheads and delivery systems - sometimes resorting to complex and arcane procedures for counting forces - in an attempt to address perceived or real imbalances in a nation's strategic posture that could lead to instability. Verification procedures are generally defined in arms control treaties and supporting documents and tend to focus on technical means and measures designed to ensure that a country is following the terms of the treaty and that it is not liable to engage in deception or outright cheating in an attempt to circumvent the spirit and the letter of the agreement. As the Obama Administration implements the articles, terms, and conditions of the recently ratified and entered-into-force New START treaty, there are already efforts within and outside of government to move well below the specified New START levels of 1550 warheads, 700 deployed strategic delivery vehicles, and 800 deployed and nondeployed strategic launchers (Inter-Continental Ballistic Missile (ICBM) silos, Submarine-Launched Ballistic Missile (SLBM) tubes on submarines, and bombers). A number of articles and opinion pieces have appeared that advocate for significantly deeper cuts in the U.S. nuclear stockpile, with some suggesting that unilateral reductions on the part of the U.S. would help coax Russia and others to follow our lead. Papers and studies prepared for the U.S. Department of Defense and at the U.S. Air War College have also been published, suggesting that nuclear forces totaling no more than about 300 warheads would be sufficient to meet U.S. national security and deterrence needs. (Davis 2011, Schaub and Forsyth 2010) Recent articles by James M. Acton and others suggest that

Assessing the allelotypic effect of two aminocyclopropane carboxylic acid synthase-encoding genes MdACS1 and MdACS3a on fruit ethylene production and softening in Malus

Science.gov (United States)

Dougherty, Laura; Zhu, Yuandi; Xu, Kenong

2016-01-01

Phytohormone ethylene largely determines apple fruit shelf life and storability. Previous studies demonstrated that MdACS1 and MdACS3a, which encode 1-aminocyclopropane-1-carboxylic acid synthases (ACS), are crucial in apple fruit ethylene production. MdACS1 is well-known to be intimately involved in the climacteric ethylene burst in fruit ripening, while MdACS3a has been regarded a main regulator for ethylene production transition from system 1 (during fruit development) to system 2 (during fruit ripening). However, MdACS3a was also shown to have limited roles in initiating the ripening process lately. To better assess their roles, fruit ethylene production and softening were evaluated at five time points during a 20-day post-harvest period in 97 Malus accessions and in 34 progeny from 2 controlled crosses. Allelotyping was accomplished using an existing marker (ACS1) for MdACS1 and two markers (CAPS866 and CAPS870) developed here to specifically detect the two null alleles (ACS3a-G289V and Mdacs3a) of MdACS3a. In total, 952 Malus accessions were allelotyped with the three markers. The major findings included: The effect of MdACS1 was significant on fruit ethylene production and softening while that of MdACS3a was less detectable; allele MdACS1–2 was significantly associated with low ethylene and slow softening; under the same background of the MdACS1 allelotypes, null allele Mdacs3a (not ACS3a-G289V) could confer a significant delay of ethylene peak; alleles MdACS1–2 and Mdacs3a (excluding ACS3a-G289V) were highly enriched in M. domestica and M. hybrid when compared with those in M. sieversii. These findings are of practical implications in developing apples of low and delayed ethylene profiles by utilizing the beneficial alleles MdACS1-2 and Mdacs3a. PMID:27231553

Programmable Power Supply for AC Switching Magnet of Proton Accelerator

CERN Document Server

Jeong, Seong-Hun; Kang Heung Sik; Lee, Chi-Hwan; Lee, Hong-Gi; Park, Ki-Hyeon; Ryu, Chun-Kil; Sik Han, Hong; Suck Suh, Hyung

2005-01-01

The 100-MeV PEFP proton linac has two proton beam extraction lines for user' experiment. Each extraction line has 5 beamlines and has 5 Hz operating frequency. An AC switching magnet is used to distribute the proton beam to the 5 beamlines, An AC switching magnet is powered by PWM-controlled bipolar switching-mode converters. This converter is designed to operate at ±350A, 5 Hz programmable step output. The power supply is employed IGBT module and has controlled by a DSP (Digital Signal Process). This paper describes the design and test results of the power supply.

Predicting AC loss in practical superconductors

International Nuclear Information System (INIS)

Goemoery, F; Souc, J; Vojenciak, M; Seiler, E; Klincok, B; Ceballos, J M; Pardo, E; Sanchez, A; Navau, C; Farinon, S; Fabbricatore, P

2006-01-01

Recent progress in the development of methods used to predict AC loss in superconducting conductors is summarized. It is underlined that the loss is just one of the electromagnetic characteristics controlled by the time evolution of magnetic field and current distribution inside the conductor. Powerful methods for the simulation of magnetic flux penetration, like Brandt's method and the method of minimal magnetic energy variation, allow us to model the interaction of the conductor with an external magnetic field or a transport current, or with both of them. The case of a coincident action of AC field and AC transport current is of prime importance for practical applications. Numerical simulation methods allow us to expand the prediction range from simplified shapes like a (infinitely high) slab or (infinitely thin) strip to more realistic forms like strips with finite rectangular or elliptic cross-section. Another substantial feature of these methods is that the real composite structure containing an array of superconducting filaments can be taken into account. Also, the case of a ferromagnetic matrix can be considered, with the simulations showing a dramatic impact on the local field. In all these circumstances, it is possible to indicate how the AC loss can be reduced by a proper architecture of the composite. On the other hand, the multifilamentary arrangement brings about a presence of coupling currents and coupling loss. Simulation of this phenomenon requires 3D formulation with corresponding growth of the problem complexity and computation time

I-F starting method with smooth transition to EMF based motion-sensorless vector control of PM synchronous motor/generator

DEFF Research Database (Denmark)

Blaabjerg, Frede; Teodorescu, Remus; Fatu, M.

2008-01-01

This paper proposes a novel hybrid motion- sensorless control system for permanent magnet synchronous motors (PMSM) using a new robust start-up method called I-f control, and a smooth transition to emf-based vector control. The I-f method is based on separate control of id, iq currents with the r......This paper proposes a novel hybrid motion- sensorless control system for permanent magnet synchronous motors (PMSM) using a new robust start-up method called I-f control, and a smooth transition to emf-based vector control. The I-f method is based on separate control of id, iq currents......-adaptive compensator to eliminate dc-offset and phase-delay. Digital simulations for PMSM start-up with full load torque are presented for different initial rotor-positions. The transitions from I-f to emf motion-sensorless vector control and back as well, at very low-speeds, are fully validated by experimental...

Early function of the Abutilon mosaic virus AC2 gene as a replication brake.

Science.gov (United States)

Krenz, Björn; Deuschle, Kathrin; Deigner, Tobias; Unseld, Sigrid; Kepp, Gabi; Wege, Christina; Kleinow, Tatjana; Jeske, Holger

2015-04-01

The C2/AC2 genes of monopartite/bipartite geminiviruses of the genera Begomovirus and Curtovirus encode important pathogenicity factors with multiple functions described so far. A novel function of Abutilon mosaic virus (AbMV) AC2 as a replication brake is described, utilizing transgenic plants with dimeric inserts of DNA B or with a reporter construct to express green fluorescent protein (GFP). Their replicational release upon AbMV superinfection or the individual and combined expression of epitope-tagged AbMV AC1, AC2, and AC3 was studied. In addition, the effects were compared in the presence and in the absence of an unrelated tombusvirus suppressor of silencing (P19). The results show that AC2 suppresses replication reproducibly in all assays and that AC3 counteracts this effect. Examination of the topoisomer distribution of supercoiled DNA, which indicates changes in the viral minichromosome structure, did not support any influence of AC2 on transcriptional gene silencing and DNA methylation. The geminiviral AC2 protein has been detected here for the first time in plants. The experiments revealed an extremely low level of AC2, which was slightly increased if constructs with an intron and a hemagglutinin (HA) tag in addition to P19 expression were used. AbMV AC2 properties are discussed with reference to those of other geminiviruses with respect to charge, modification, and size in order to delimit possible reasons for the different behaviors. The (A)C2 genes encode a key pathogenicity factor of begomoviruses and curtoviruses in the plant virus family Geminiviridae. This factor has been implicated in the resistance breaking observed in agricultural cotton production. AC2 is a multifunctional protein involved in transcriptional control, gene silencing, and regulation of basal biosynthesis. Here, a new function of Abutilon mosaic virus AC2 in replication control is added as a feature of this protein in viral multiplication, providing a novel finding on

Low start-up voltage dc–dc converter with negative voltage control for thermoelectric energy harvesting

Directory of Open Access Journals (Sweden)

Pui-Sun Lei

2015-01-01

Full Text Available This Letter presents a low start-up voltage dc–dc converter for low-power thermoelectric systems which uses a native n-type MOS transistor as the start-up switch. The start-up voltage of the proposed converter is 300 mV and the converter does not need batteries to start up. The negative voltage control is proposed to reduce the leakage current caused by native n-type transistor and increase the efficiency. The proposed converter was designed using standard 0.18 µm CMOS process with chip size of 0.388 mm^2. The peak efficiency is 63% at load current of 1.5 mA. The proposed converter provides output voltage >1 V at maximum load current of 3.2 mA.

Electrically heated catalysts for cold-start emission control on gasoline- and methanol-fueled vehicles

International Nuclear Information System (INIS)

Heimrich, M.J.; Albu, S.; Ahuja, M.

1992-01-01

Cold-start emissions from current technology vehicles equipped with catalytic converters can account for over 80 percent of the emissions produced during the Federal Test Procedure (FTP). Excessive pollutants can be emitted for a period of one to two minutes following cold engine starting, partially because the catalyst has not reached an efficient operating temperature. Electrically heated catalysts, which are heated prior to engine starting, have been identified as a potential strategy for controlling cold-start emissions. This paper summarizes the emission results of three gasoline-fueled and three methanol-fueled vehicles equipped with electrically heated catalyst systems. Results from these vehicles demonstrate that heated catalyst technology can provide FTP emission levels of nonmethane organic gases (NMOG), carbon monoxide (CO), and oxides of nitrogen (NO x ) that show promise of meeting the Ultra-Low Emission Vehicle (ULEV) standards established by the California Air Resources Board

Unbalanced Voltage Compensation in Low Voltage Residential AC Grids

DEFF Research Database (Denmark)

Trintis, Ionut; Douglass, Philip; Munk-Nielsen, Stig

2016-01-01

This paper describes the design and test of a control algorithm for active front-end rectifiers that draw power from a residential AC grid to feed heat pump loads. The control algorithm is able to control the phase to neutral or phase to phase RMS voltages at the point of common coupling...

Arthroscopically Assisted Reconstruction of Acute Acromioclavicular Joint Dislocations: Anatomic AC Ligament Reconstruction With Protective Internal Bracing—The “AC-RecoBridge” Technique

Science.gov (United States)

Izadpanah, Kaywan; Jaeger, Martin; Ogon, Peter; Südkamp, Norbert P.; Maier, Dirk

2015-01-01

An arthroscopically assisted technique for the treatment of acute acromioclavicular joint dislocations is presented. This pathology-based procedure aims to achieve anatomic healing of both the acromioclavicular ligament complex (ACLC) and the coracoclavicular ligaments. First, the acromioclavicular joint is reduced anatomically under macroscopic and radiologic control and temporarily transfixed with a K-wire. A single-channel technique using 2 suture tapes provides secure coracoclavicular stabilization. The key step of the procedure consists of the anatomic repair of the ACLC (“AC-Reco”). Basically, we have observed 4 patterns of injury: clavicular-sided, acromial-sided, oblique, and midportion tears. Direct and/or transosseous ACLC repair is performed accordingly. Then, an X-configured acromioclavicular suture tape cerclage (“AC-Bridge”) is applied under arthroscopic assistance to limit horizontal clavicular translation to a physiological extent. The AC-Bridge follows the principle of internal bracing and protects healing of the ACLC repair. The AC-Bridge is tightened on top of the repair, creating an additional suture-bridge effect and promoting anatomic ACLC healing. We refer to this combined technique of anatomic ACLC repair and protective internal bracing as the “AC-RecoBridge.” A detailed stepwise description of the surgical technique, including indications, technical pearls and pitfalls, and potential complications, is given. PMID:26052493

Estimating BrAC from transdermal alcohol concentration data using the BrAC estimator software program.

Science.gov (United States)

Luczak, Susan E; Rosen, I Gary

2014-08-01

Transdermal alcohol sensor (TAS) devices have the potential to allow researchers and clinicians to unobtrusively collect naturalistic drinking data for weeks at a time, but the transdermal alcohol concentration (TAC) data these devices produce do not consistently correspond with breath alcohol concentration (BrAC) data. We present and test the BrAC Estimator software, a program designed to produce individualized estimates of BrAC from TAC data by fitting mathematical models to a specific person wearing a specific TAS device. Two TAS devices were worn simultaneously by 1 participant for 18 days. The trial began with a laboratory alcohol session to calibrate the model and was followed by a field trial with 10 drinking episodes. Model parameter estimates and fit indices were compared across drinking episodes to examine the calibration phase of the software. Software-generated estimates of peak BrAC, time of peak BrAC, and area under the BrAC curve were compared with breath analyzer data to examine the estimation phase of the software. In this single-subject design with breath analyzer peak BrAC scores ranging from 0.013 to 0.057, the software created consistent models for the 2 TAS devices, despite differences in raw TAC data, and was able to compensate for the attenuation of peak BrAC and latency of the time of peak BrAC that are typically observed in TAC data. This software program represents an important initial step for making it possible for non mathematician researchers and clinicians to obtain estimates of BrAC from TAC data in naturalistic drinking environments. Future research with more participants and greater variation in alcohol consumption levels and patterns, as well as examination of gain scheduling calibration procedures and nonlinear models of diffusion, will help to determine how precise these software models can become. Copyright © 2014 by the Research Society on Alcoholism.

Start-up conditions and the performance of women - and men - controlled businesses in manufacturing industries

Directory of Open Access Journals (Sweden)

Otilia Driga

2010-01-01

Full Text Available Recent research into the economic performance of women-controlled firms suggests that their underperformance may not be the result of differences in the managerial ability of women as compared to men, and that it may in fact be a consequence of differing levels of start-up resources. Using accounting data, we examine the effects that selected start-up conditions have had on the observed economic performance of a sample of 4450 Spanish manufacturing firms. The results, which indicate significant differences in the initial conditions and show lower levels of assets and employee numbers in women-controlled firms, have implications for the economic performance of such firms.

Reactor core flow rate control system

International Nuclear Information System (INIS)

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

1996-01-01

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

Detection of combustion start in the controlled auto ignition engine by wavelet transform of the engine block vibration signal

International Nuclear Information System (INIS)

Kim, Seonguk; Min, Kyoungdoug

2008-01-01

The CAI (controlled auto ignition) engine ignites fuel and air mixture by trapping high temperature burnt gas using a negative valve overlap. Due to auto ignition in CAI combustion, efficiency improvements and low level NO x emission can be obtained. Meanwhile, the CAI combustion regime is restricted and control parameters are limited. The start of combustion data in the compressed ignition engine are most critical for controlling the overall combustion. In this research, the engine block vibration signal is transformed by the Meyer wavelet to analyze CAI combustion more easily and accurately. Signal acquisition of the engine block vibration is a more suitable method for practical use than measurement of in-cylinder pressure. A new method for detecting combustion start in CAI engines through wavelet transformation of the engine block vibration signal was developed and results indicate that it is accurate enough to analyze the start of combustion. Experimental results show that wavelet transformation of engine block vibration can track the start of combustion in each cycle. From this newly developed method, the start of combustion data in CAI engines can be detected more easily and used as input data for controlling CAI combustion

Detection of combustion start in the controlled auto ignition engine by wavelet transform of the engine block vibration signal

Science.gov (United States)

Kim, Seonguk; Min, Kyoungdoug

2008-08-01

The CAI (controlled auto ignition) engine ignites fuel and air mixture by trapping high temperature burnt gas using a negative valve overlap. Due to auto ignition in CAI combustion, efficiency improvements and low level NOx emission can be obtained. Meanwhile, the CAI combustion regime is restricted and control parameters are limited. The start of combustion data in the compressed ignition engine are most critical for controlling the overall combustion. In this research, the engine block vibration signal is transformed by the Meyer wavelet to analyze CAI combustion more easily and accurately. Signal acquisition of the engine block vibration is a more suitable method for practical use than measurement of in-cylinder pressure. A new method for detecting combustion start in CAI engines through wavelet transformation of the engine block vibration signal was developed and results indicate that it is accurate enough to analyze the start of combustion. Experimental results show that wavelet transformation of engine block vibration can track the start of combustion in each cycle. From this newly developed method, the start of combustion data in CAI engines can be detected more easily and used as input data for controlling CAI combustion.

Why START?

International Nuclear Information System (INIS)

Mendelsohn, J.

1991-01-01

Barring some major unexpected downturn in US-Soviet relations, it seems likely that the long-awaited Strategic Arms Reduction Talks (START) treaty will be signed sometime in 1991. Under negotiation for the past nine years, public acceptance and Senate approval of a START treaty will be facilitated by the generally less confrontational East-West relationship which has evolved over that time, by the growing constraints on the US defense budget, and by the obvious merits of the treaty itself. Not only will the nearly complete START treaty be an extremely useful and powerful arms control agreement, it is also decidedly advantageous to US security interests. First and foremost, a START treaty will cap and reduce the steady buildup of nuclear weapons that has characterized the last 30 years of the US-Soviet strategic relationship. As a result of the basic outline originally agreed to at the Reykjavik summit, START will take a 25 to 35 percent bite out of existing nuclear arsenals, impose approximately a 50 percent cut in overall Soviet ballistic missile warheads and throw-weight (lifting power or payload capacity), and produce an exact 50 percent cut in Soviet SS-18 missiles

Apple MdACS6 Regulates Ethylene Biosynthesis During Fruit Development Involving Ethylene-Responsive Factor.

Science.gov (United States)

Li, Tong; Tan, Dongmei; Liu, Zhi; Jiang, Zhongyu; Wei, Yun; Zhang, Lichao; Li, Xinyue; Yuan, Hui; Wang, Aide

2015-10-01

Ethylene biosynthesis in plants involves different 1-aminocyclopropane-1-carboxylic acid synthase (ACS) genes. The regulation of each ACS gene during fruit development is unclear. Here, we characterized another apple (Malus×domestica) ACS gene, MdACS6. The transcript of MdACS6 was observed not only in fruits but also in other tissues. During fruit development, MdACS6 was initiated at a much earlier stage, whereas MdACS3a and MdACS1 began to be expressed at 35 d before harvest and immediateley after harvest, respectively. Moreover, the enzyme activity of MdACS6 was significantly lower than that of MdACS3a and MdACS1, accounting for the low ethylene biosynthesis in young fruits. Overexpression of MdACS6 (MdACS6-OE) by transient assay in apple showed enhanced ethylene production, and MdACS3a was induced in MdACS6-OE fruits but not in control fruits. In MdACS6 apple fruits silenced by the virus-induced gene silencing (VIGS) system (MdACS6-AN), neither ethylene production nor MdACS3a transcript was detectable. In order to explore the mechanism through which MdACS3a was induced in MdACS6-OE fruits, we investigated the expression of apple ethylene-responsive factor (ERF) genes. The results showed that the expression of MdERF2 was induced in MdACS6-OE fruits and inhibited in MdACS6-AN fruits. Yeast one-hybrid assay showed that MdERF2 protein could bind to the promoter of MdACS3a. Moreover, down-regulation of MdERF2 in apple flesh callus led to a decrease of MdACS3a expression, demonstrating the regulation of MdERF2 on MdACS3a. The mechanism through which MdACS6 regulates the action of MdACS3a was discussed. © The Author 2015. Published by Oxford University Press on behalf of Japanese Society of Plant Physiologists. All rights reserved. For permissions, please email: journals.permissions@oup.com.

Direct AC–AC grid interface converter for ocean wave energy system

International Nuclear Information System (INIS)

Tsang, K.M.; Chan, W.L.

2015-01-01

Highlights: • Novel power grid interface converter for ocean wave energy system. • Unlike conventional approach, generator output is directly converted into fixed frequency AC for synchronous connection. • High conversion efficient and power quality could be achieved. - Abstract: Ocean wave energy is very promising. However, existing systems are using rectifying circuits to convert variable voltage and variable frequency output of electric generator into DC voltage and then use grid-tied inverter to connect to the power grid. Such arrangement will not only reduce the overall efficient but also increase the cost of the system. A direct AC–AC converter is a desirable solution. In this paper, a six-switch AC–AC converter has been proposed as a single phase grid-connected interface. New switching scheme has been derived for the converter such that the virtual input AC–DC conversion and the output DC–AC conversion can be decoupled. State-space averaging model and pulse width modulation scheme have been derived for the converter. As the input and the output operations can be decoupled, two independent controllers have been designed to handle the input AC–DC regulation and the output DC–AC regulation. The proposed scheme demands for two separate duty ratios and novel switching scheme has been derived to realize the combined duty ratios in one switching cycle. Power regulation, harmonics elimination and power factor correction control algorithms have also been derived for the converter when it is connected to the supply grid. Experimental results of a small scale model are included to demonstrate the effectiveness of the proposed switching and control schemes

The Hubble Legacy Archive ACS grism data

Science.gov (United States)

Kümmel, M.; Rosati, P.; Fosbury, R.; Haase, J.; Hook, R. N.; Kuntschner, H.; Lombardi, M.; Micol, A.; Nilsson, K. K.; Stoehr, F.; Walsh, J. R.

2011-06-01

A public release of slitless spectra, obtained with ACS/WFC and the G800L grism, is presented. Spectra were automatically extracted in a uniform way from 153 archival fields (or "associations") distributed across the two Galactic caps, covering all observations to 2008. The ACS G800L grism provides a wavelength range of 0.55-1.00 μm, with a dispersion of 40 Å/pixel and a resolution of ~80 Å for point-like sources. The ACS G800L images and matched direct images were reduced with an automatic pipeline that handles all steps from archive retrieval, alignment and astrometric calibration, direct image combination, catalogue generation, spectral extraction and collection of metadata. The large number of extracted spectra (73,581) demanded automatic methods for quality control and an automated classification algorithm was trained on the visual inspection of several thousand spectra. The final sample of quality controlled spectra includes 47 919 datasets (65% of the total number of extracted spectra) for 32 149 unique objects, with a median iAB-band magnitude of 23.7, reaching 26.5 AB for the faintest objects. Each released dataset contains science-ready 1D and 2D spectra, as well as multi-band image cutouts of corresponding sources and a useful preview page summarising the direct and slitless data, astrometric and photometric parameters. This release is part of the continuing effort to enhance the content of the Hubble Legacy Archive (HLA) with highly processed data products which significantly facilitate the scientific exploitation of the Hubble data. In order to characterize the slitless spectra, emission-line flux and equivalent width sensitivity of the ACS data were compared with public ground-based spectra in the GOODS-South field. An example list of emission line galaxies with two or more identified lines is also included, covering the redshift range 0.2 - 4.6. Almost all redshift determinations outside of the GOODS fields are new. The scope of science projects

Development of software to improve AC power quality on large spacecraft

Science.gov (United States)

Kraft, L. Alan

1991-01-01

To insure the reliability of a 20 kHz, alternating current (AC) power system on spacecraft, it is essential to analyze its behavior under many adverse operating conditions. Some of these conditions include overloads, short circuits, switching surges, and harmonic distortions. Harmonic distortions can become a serious problem. It can cause malfunctions in equipment that the power system is supplying, and, during distortions such as voltage resonance, it can cause equipment and insulation failures due to the extreme peak voltages. To address the harmonic distortion issue, work was begun under the 1990 NASA-ASEE Summer Faculty Fellowship Program. Software, originally developed by EPRI, called HARMFLO, a power flow program capable of analyzing harmonic conditions on three phase, balanced, 60 Hz AC power systems, was modified to analyze single phase, 20 kHz, AC power systems. Since almost all of the equipment used on spacecraft power systems is electrically different from equipment used on terrestrial power systems, it was also necessary to develop mathematical models for the equipment to be used on the spacecraft. The modelling was also started under the same fellowship work period. Details of the modifications and models completed during the 1990 NASA-ASEE Summer Faculty Fellowship Program can be found in a project report. As a continuation of the work to develop a complete package necessary for the full analysis of spacecraft AC power system behavior, deployment work has continued through NASA Grant NAG3-1254. This report details the work covered by the above mentioned grant.

Changes in stimulus and response AC/A ratio with vision therapy in Convergence Insufficiency.

Science.gov (United States)

Singh, Neeraj Kumar; Mani, Revathy; Hussaindeen, Jameel Rizwana

To evaluate the changes in the stimulus and response Accommodative Convergence to Accommodation (AC/A) ratio following vision therapy (VT) in Convergence Insufficiency (CI). Stimulus and response AC/A ratio were measured on twenty five CI participants, pre and post 10 sessions of VT. Stimulus AC/A ratio was measured using the gradient method and response AC/A ratio was calculated using modified Thorington technique with accommodative responses measured using WAM-5500 open-field autorefractor. The gradient stimulus and response AC/A cross-link ratios were compared with thirty age matched controls. Mean age of the CI and control participants were 23.3±5.2 years and 22.7±4.2 years, respectively. The mean stimulus and response AC/A ratio for CI pre therapy was 2.2±0.72 and 6.3±2.0 PD/D that changed to 4.2±0.9 and 8.28±3.31 PD/D respectively post vision therapy and these changes were statistically significant (paired t-test; paccommodation parameters in subjects with convergence insufficiency. This represents the plasticity of the AC/A crosslink ratios that could be achieved with vision therapy in CI. Copyright © 2016 Spanish General Council of Optometry. Published by Elsevier España, S.L.U. All rights reserved.

pH-controlled Bacillus thuringiensis Cry1Ac protoxin loading and release from polyelectrolyte microcapsules.

Directory of Open Access Journals (Sweden)

Wenhui Yang

Full Text Available Crystal proteins synthesized by Bacillus thuringiensis (Bt have been used as biopesticides because of their toxicity to the insect larval hosts. To protect the proteins from environmental stress to extend their activity, we have developed a new microcapsule formulation. Poly (acrylic acid (PAH and poly (styrene sulfonate (PSS were fabricated through layer-by-layer self-assembly based on a CaCO(3 core. Cry1Ac protoxins were loaded into microcapsules through layer-by-layer self-assembly at low pH, and the encapsulated product was stored in water at 4°C. Scanning electron microscopy (SEM was used to observe the morphology of the capsules. To confirm the successful encapsulation, the loading results were observed with a confocal laser scattering microscope (CLSM, using fluorescein-labeled Cry1Ac protoxin (FITC-Cry1Ac. The protoxins were released from the capsule under the alkaline condition corresponding to the midgut of certain insects, a condition which seldom exists elsewhere in the environment. The following bioassay experiment demonstrated that the microcapsules with Cry1Ac protoxins displayed approximately equivalent insecticidal activity to the Asian corn borer compared with free Cry1Ac protoxins, and empty capsules proved to have no effect on insects. Further result also indicated that the formulation could keep stable under the condition of heat and desiccation. These results suggest that this formulation provides a promising methodology that protects protoxins from the environment and releases them specifically in the target insects' midgut, which has shown potential as biopesticide in the field.

Synthesis of state observer and nonlinear output feedback controller design of AC machines

International Nuclear Information System (INIS)

Al-Tahir, Ali Abdul Razzaq

2016-01-01

The research work developed in this thesis has been mainly devoted to the observation and sensor-less control problems of electrical systems. Three major contributions have been carried out using the high - gain concept and output feedback adaptive nonlinear control for online UPS. In this thesis, we dealt with synthesis of sampled high - gain observers for nonlinear systems application to PMSMs and DFIGs. We particularly focus on two constraints: sampling effect and tracking unmeasured mechanical and magnetic state variables. The first contribution consists in a high gain observer design that performs a relatively accurate estimation of both mechanical and magnetic state variable using the available measurements on stator currents and voltages of PMSM. We propose a global exponential observer having state predictor for a class of nonlinear globally Lipschitz system. In second contribution, we proposed a novel non - standard HGO design for non-injective feedback relation application to variable speed DFIG based WPGS. Meanwhile, a reduced system model is analyzed, provided by observability test to check is it possible synthesis state observer for sensor-less control. In last contribution, an adaptive observer for states and parameters estimation are designed for a class of state - affine systems application to output feedback adaptive nonlinear control of three-phase AC/DC boost power converter for online UPS systems. Basically, the problem focused on cascade nonlinear adaptive controller that is developed making use Lyapunov theory. The parameters uncertainties are processed by the practical control laws under back-stepping design techniques with capacity of adaptation. (author)

Light-controlled endosomal escape of the novel CD133-targeting immunotoxin AC133-saporin by photochemical internalization - A minimally invasive cancer stem cell-targeting strategy.

Science.gov (United States)

Bostad, Monica; Olsen, Cathrine Elisabeth; Peng, Qian; Berg, Kristian; Høgset, Anders; Selbo, Pål Kristian

2015-05-28

The cancer stem cell (CSC) marker CD133 is an attractive target to improve antitumor therapy. We have used photochemical internalization (PCI) for the endosomal escape of the novel CD133-targeting immunotoxin AC133-saporin (PCIAC133-saporin). PCI employs an endocytic vesicle-localizing photosensitizer, which generates reactive oxygen species upon light-activation causing a rupture of the vesicle membranes and endosomal escape of entrapped drugs. Here we show that AC133-saporin co-localizes with the PCI-photosensitizer TPCS2a, which upon light exposure induces cytosolic release of AC133-saporin. PCI of picomolar levels of AC133-saporin in colorectal adenocarcinoma WiDr cells blocked cell proliferation and induced 100% inhibition of cell viability and colony forming ability at the highest light doses, whereas no cytotoxicity was obtained in the absence of light. Efficient PCI-based CD133-targeting was in addition demonstrated in the stem-cell-like, triple negative breast cancer cell line MDA-MB-231 and in the aggressive malignant melanoma cell line FEMX-1, whereas no enhanced targeting was obtained in the CD133-negative breast cancer cell line MCF-7. PCIAC133-saporin induced mainly necrosis and a minimal apoptotic response based on assessing cleavage of caspase-3 and PARP, and the TUNEL assay. PCIAC133-saporin resulted in S phase arrest and reduced LC3-II conversion compared to control treatments. Notably, co-treatment with Bafilomycin A1 and PCIAC133-saporin blocked LC3-II conversion, indicating a termination of the autophagic flux in WiDr cells. For the first time, we demonstrate laser-controlled targeting of CD133 in vivo. After only one systemic injection of AC133-saporin and TPCS2a, a strong anti-tumor response was observed after PCIAC133-saporin. The present PCI-based endosomal escape technology represents a minimally invasive strategy for spatio-temporal, light-controlled targeting of CD133+ cells in localized primary tumors or metastasis. Copyright © 2015

Dielectric behavior and ac electrical conductivity of nanocrystalline nickel aluminate

International Nuclear Information System (INIS)

Kurien, Siby; Mathew, Jose; Sebastian, Shajo; Potty, S.N.; George, K.C.

2006-01-01

Nanocrystalline nickel aluminate was prepared by chemical co-precipitation, and nanoparticles having different particle size were obtained by annealing the precursor at different temperatures. The TG/DTA measurements showed thermal decomposition was a three-step process with crystallisation of the spinel phase started at a temperature 420 deg. C. The X-ray diffraction analysis confirmed that the specimen began to crystallise on annealing above 420 deg. C and became almost crystalline at about 900 deg. C. The particle sizes were calculated from XRD. Dielectric properties of nickel aluminate were studied as a function of the frequency of the applied ac signal at different temperatures. It was seen the real dielectric constant ε', and dielectric loss tan δ decreased with frequency of applied field while the ac conductivity increased as the frequency of the applied field increased. The dielectric relaxation mechanism is explained by considering nanostructured NiAl 2 O 4 as a carrier-dominated dielectric with high density of hopping charge carriers. The variation of ε' with different particle size depends on several interfacial region parameters, which change with the average particle size

Control of a post-combustion CO2 capture plant during process start-up and load variations

DEFF Research Database (Denmark)

Gaspar, Jozsef; Jørgensen, John Bagterp; Fosbøl, Philip Loldrup

2015-01-01

Dynamic and flexible operation of a carbon capture plant is important as thermal power plants must be operated very flexibly to accommodate large shares of intermittent energy sources such as wind and solar energy. To facilitate such operation, dynamic models for simulation, optimization...... and control system design are crucial. In this paper, we present a dynamic mathematical model for the absorption and desorption columns in a carbon capture plant. Moreover, we implement a decentralized proportional-integral (PI) based control scheme and we evaluate the performance of the control structure...... for various operational procedures, e.g. start-up, load changes, noise on the flue gas flow rate and composition. Note that the carbon capture plant is based on the solvent storage configuration. To the authors knowledge, this is the first paper addressing the issue of start-up operation and control of carbon...

Cost effective second generation AC-modules: Development and testing aspects

International Nuclear Information System (INIS)

Islam, Saiful; Woyte, Achim; Belmans, Ronnie; Heskes, Peter; Rooij, P.M.; Hogedoorn, Ron

2006-01-01

In the framework of the European research project PV2GO, a new AC-module inverter was developed, taking into account all relevant aspects from a European market's point of view (standards, market, application, and research and development goals). The project goal was to achieve the overall system costs of 3 Euro per Wp for a modular plug-and-play photovoltaic system. For the photovoltaic-module, a standard 130-Wp Eurosolare module was chosen. The research and development (R and D) goal was to develop an advanced DC-control system consisting of a state-of-the-art programmable digital device and an Application Specific Integrated Circuit (ASIC) for the AC-control of the inverter. According to the topology concept, thermal and magnetic designs were optimized with regard to production technology and packaging for large-scale production. The new AC-modules were tested in a number of field-test sites in various parts of Europe and their reliability was assessed through Highly Accelerated Stress Tests. Efficiency and power quality have been tested in the laboratory. Further in the PV2GO project an optimization study of the manufacturing process of the new generation of AC-modules for high volume output was done. Another task was the pre-certification procedure to assure compliance with the European guidelines and standards

The AC photovoltaic module is here!

Science.gov (United States)

Strong, Steven J.; Wohlgemuth, John H.; Wills, Robert H.

1997-02-01

This paper describes the design, development, and performance results of a large-area photovoltaic module whose electrical output is ac power suitable for direct connection to the utility grid. The large-area ac PV module features a dedicated, integrally mounted, high-efficiency dc-to-ac power inverter with a nominal output of 250 watts (STC) at 120 Vac, 60 H, that is fully compatible with utility power. The module's output is connected directly to the building's conventional ac distribution system without need for any dc wiring, string combiners, dc ground-fault protection or additional power-conditioning equipment. With its advantages, the ac photovoltaic module promises to become a universal building block for use in all utility-interactive PV systems. This paper discusses AC Module design aspects and utility interface issues (including islanding).

The Effects of Theta and Gamma tACS on Working Memory and Electrophysiology

Directory of Open Access Journals (Sweden)

Anja Pahor

2018-01-01

Full Text Available A single blind sham-controlled study was conducted to explore the effects of theta and gamma transcranial alternating current stimulation (tACS on offline performance on working memory tasks. In order to systematically investigate how specific parameters of tACS affect working memory, we manipulated the frequency of stimulation (theta frequency vs. gamma frequency, the type of task (n-back vs. change detection task and the content of the tasks (verbal vs. figural stimuli. A repeated measures design was used that consisted of three sessions: theta tACS, gamma tACS and sham tACS. In total, four experiments were conducted which differed only with respect to placement of tACS electrodes (bilateral frontal, bilateral parietal, left fronto-parietal and right-fronto parietal. Healthy female students (N = 72 were randomly assigned to one of these groups, hence we were able to assess the efficacy of theta and gamma tACS applied over different brain areas, contrasted against sham stimulation. The pre-post/sham resting electroencephalogram (EEG analysis showed that theta tACS significantly affected theta amplitude, whereas gamma tACS had no significant effect on EEG amplitude in any of the frequency bands of interest. Gamma tACS did not significantly affect working memory performance compared to sham, and theta tACS led to inconsistent changes in performance on the n-back tasks. Active theta tACS significantly affected P3 amplitude and latency during performance on the n-back tasks in the bilateral parietal and right-fronto parietal protocols.

AC power losses in Bi-2223/Ag HTS tapes

International Nuclear Information System (INIS)

Savvides, N.; Reilly, D.; Mueller, K.-H.; Herrmann, J.

1998-01-01

Full text: We report measurements at 77 K of the transport ac losses of Bi-2223/Ag composite tapes. The investigated tapes vary from single filament to multifilament construction and include both conventional tapes and other conductor shapes with twisted filaments. The self-field ac losses were determined at 77 K and 60 Hz as a function of ac current amplitude (0 - 100 A). We observe different behaviour among tapes depending on their quality and strain history. For 'good' virgin tapes the experimental data are well described by the Norris equations for the dependence of power loss P on the amplitude I m of the transport current. The data of good monofilament tapes are fitted to the Norris equation P ∼ I m n for an elliptical cross section (ie. n = 3) and the data of good multifilament tapes are fitted to the Norris equation for a rectangular strip (ie. n = 4). Many specimens, however, show a range of behaviour with lower values of n. Based on our work on the effect of strain on the dc transport properties of tapes, we carried out detailed investigations of the effect of controlled applied bend strain on the ac loss. Our results show that irreversible damage to superconducting filaments (ie. cracks) cause the ac loss to rise and n to decrease with increasing strain. In addition, applied strains much greater than the irreversible strain limit cause the ac loss to increase by several orders of magnitude and become ohmic in character with n = 2. Theoretical work is in progress to model the observed behaviour

Modelling and Control Design of a Dual Buck-Boost AC/DC Converter Used in the DC Nano-Grid

DEFF Research Database (Denmark)

Wu, Weimin; Liu, Yuan; Wang, Houqing

2016-01-01

Due to widely used DC characterized loads and more distributed power generation sources, the DC Nano-grid becomes more and more popular and seen as an alternative to the AC-grid in future. For the safety considerations, the DC Nano-grid should provide reliable grounding for the residential loads...... like the low voltage AC power system. In this paper, a dual Buck-Boost AC/DC converter for use in the united grounding configuration based DC Nano-grid with three terminal outputs is proposed. It will be much easy to construct an efficient DC Nano-grid based on the existing low AC power system by using...

Fixed switching frequency applied in single-phase boost AC to DC converter

International Nuclear Information System (INIS)

Chen, T.-C.; Ren, T.-J.; Ou, J.-C.

2009-01-01

The fixed switching frequency control for a single-phase boost AC to DC converter to achieve a sinusoidal line current and unity power factor is proposed in this paper. The relation between the line current error and the fixed switching frequency was developed. For a limit line current error, the minimum switching frequency for a boost AC to DC converter can be achieved. The proposed scheme was implemented using a 32-bit digital signal processor TMS320C32. Simulations and experimental results demonstrate the feasibility and fast dynamic response of the proposed control strategy.

Causes and effects of vital instrumentation and control power supply bus failures

International Nuclear Information System (INIS)

Muhlheim, M.D.; Murphy, G.A.

1987-01-01

This article presents the results of a study in which the objective was to evaluate nuclear power-plant operating experience to identify the causes and the effects of vital instrumentation and control (I and C) power supply bus failures. Vital I and C power is normally provided to essential instrumentation and controls through either vital d-c or a-c power supply systems. The vital d-c power supply system generally provides control power for starting the diesel generators, for operating electrical circuit breakers, and for controlling various logic circuits. The vital d-c power system also supplies vital a-c power through an inverter. The vital a-c power supply system generally feeds the reactor protection system channels, the engineered safety features actuation system channels, and critical instrumentation in the control room. The leading cause of vital bus failures is inverter failures; other causes are human errors, battery charger failures, and miscellaneous failures. The effects of these failures are that the margin of safety can be degraded by (1) denying key information to the operators, (2) inducing plant transients, (3) causing safety injection actuations, and (4) causing the loss of shutdown cooling flow

Control of a post-combustion CO₂ capture plantduring process start-up and load variations

DEFF Research Database (Denmark)

Gaspar, Jozsef; Jørgensen, John Bagterp; Fosbøl, Philip Loldrup

2015-01-01

for various operational procedures, e.g. start-up, load changes, noise on the flue gas flow rate and composition. Note that the carbon capture plant is based on the solvent storage configuration. To the authors knowledge, this is the first paper addressing the issue of start-up operation and control of carbon...

Method for calculation of the dynamic behaviour of permanent-magnet synchronous machines controlled by a thyristor-based softstarter; Berechnungsmethode zur Bestimmung des dynamischen Verhaltens von permanentmagneterregten Synchronmaschinen am Drehstromsteller

Energy Technology Data Exchange (ETDEWEB)

Benecke, Marcel; Lindemann, Andreas [Magdeburg Univ. (Germany). Inst. fuer Elektrische Energiesysteme; Griepentrog, Gerd [Siemens AG (Germany). Corporate Technology CT T DE

2011-07-01

Permanentmagnet synchronous machines (PMSM) show lower losses compared to induction machines (IM) due to the lack of rotor losses which are typical only for IM. Hence, for many applications with a fixed rotational speed such as fans or pumps the PMSM would be a good choice in case the PMSM is directly connected to the grid without any converter in between at nominal speed. This would be an optimal solution with respect to efficiency and losses. Because the PMSM is not able to speed up when directly connected to the grid, it has normally to be started using a frequency converter or it has to be equipped with a start-up short-circuit cage which would develop an asynchronous torque. A cost effective alternative is to use AC voltage controller or softstarter based on thyristors to speed up the PMSM and bridge the AC voltage controller once the PMSM has reached nominal speed. This paper presents a calculation method to predict the dynamic behaviour of a PMSM when fed by a thyristor-based AC voltage controller. (orig.)

Levitação acústica

OpenAIRE

Andrade, Marco Aurélio Brizzotti; Pérez, Nicolás; Adamowski, Julio Cezar

2015-01-01

A levitação acústica pode ser uma ferramenta valiosa para auxiliar estudantes de graduação a aprender conceitos básicos de física, tais como movimento harmônico simples, ondas acústicas estacionárias, e energia potencial. Neste artigo, apresentamos o princípio de funcionamento de um levitador acústico e explicamos como aplicar as equações básicas da acústica para determinar a força de radiação acústica que atua numa esfera em uma onda estacionária. Acoustic levitation can be a valuable too...

Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers

DEFF Research Database (Denmark)

Ljusev, Petar; Andersen, Michael Andreas E.

2004-01-01

This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion...

I-f Starting and Active Flux Based Sensorless Vector Control of Reluctance Synchronous Motors, with Experiments

DEFF Research Database (Denmark)

Agarlita, Sorin-Christian; Fatu, M.; Tutelea, L. N.

2010-01-01

This paper presents a novel, hybrid, motion sensorless control of an axially laminated anisotropic (ALA) reluctance synchronous machine (RSM). By separately controlling Id and Iq currents with the reference currents Id*, Iq* being held constant, and ramping the reference frequency, the motor starts...

New Subarray Readout Patterns for the ACS Wide Field Channel

Science.gov (United States)

Golimowski, D.; Anderson, J.; Arslanian, S.; Chiaberge, M.; Grogin, N.; Lim, Pey Lian; Lupie, O.; McMaster, M.; Reinhart, M.; Schiffer, F.; Serrano, B.; Van Marshall, M.; Welty, A.

2017-04-01

At the start of Cycle 24, the original CCD-readout timing patterns used to generate ACS Wide Field Channel (WFC) subarray images were replaced with new patterns adapted from the four-quadrant readout pattern used to generate full-frame WFC images. The primary motivation for this replacement was a substantial reduction of observatory and staff resources needed to support WFC subarray bias calibration, which became a new and challenging obligation after the installation of the ACS CCD Electronics Box Replacement during Servicing Mission 4. The new readout patterns also improve the overall efficiency of observing with WFC subarrays and enable the processing of subarray images through stages of the ACS data calibration pipeline (calacs) that were previously restricted to full-frame WFC images. The new readout patterns replace the original 512×512, 1024×1024, and 2048×2046-pixel subarrays with subarrays having 2048 columns and 512, 1024, and 2048 rows, respectively. Whereas the original square subarrays were limited to certain WFC quadrants, the new rectangular subarrays are available in all four quadrants. The underlying bias structure of the new subarrays now conforms with those of the corresponding regions of the full-frame image, which allows raw frames in all image formats to be calibrated using one contemporaneous full-frame "superbias" reference image. The original subarrays remain available for scientific use, but calibration of these image formats is no longer supported by STScI.

Heating calculation features at self-start of large asynchronous motor

Science.gov (United States)

Shevchenko, A. A.; Temlyakova, Z. S.; Grechkin, V. V.; Vilberger, M. E.

2017-10-01

The article proposes a method for optimizing the incremental heating calculation in the active volume of a large asynchronous motor for certain kinds of load characteristics. The incremental heating calculation is conditioned by the need to determine the aging level of the insulation and to predict a decrease in the electric machine service life. The method for optimizing the incremental heating calculation of asynchronous motor active volume is based on the automation of calculating the heating when simulating the self-starting process of the motor after eliminating an AC drop.

AcMNPV ac143 (odv-e18) is essential for mediating budded virus production and is the 30th baculovirus core gene

International Nuclear Information System (INIS)

McCarthy, Christina B.; Theilmann, David A.

2008-01-01

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) ac143 (odv-e18) is a late gene that encodes for a predicted 9.6 kDa structural protein that locates to the occlusion derived viral envelope and viral induced intranuclear microvesicles [Braunagel, S.C., He, H., Ramamurthy, P., and Summers, M.D. (1996). Transcription, translation, and cellular localization of three Autographa californica nuclear polyhedrosis virus structural proteins: ODV-E18, ODV-E35, and ODV-EC27. Virology 222, 100-114.]. In this study we demonstrate that ac143 is actually a previously unrecognized core gene and that it is essential for mediating budded virus production. To examine the role of ac143 in the baculovirus life cycle, we used the AcMNPV bacmid system to generate an ac143 knockout (KO) virus (AcBAC ac142REP-ac143KO ). Fluorescence and light microscopy showed that infection by AcBAC ac142REP-ac143KO is limited to a single cell and titration assays confirmed that AcBAC ac142REP-ac143KO was unable to produce budded virus (BV). Progression to very late phases of the viral infection was evidenced by the development of occlusion bodies in the nuclei of transfected cells. This correlated with the fact that viral DNA replication was unaffected in AcBAC ac142REP-ac143KO transfected cells. The entire ac143 promoter, which includes three late promoter motifs, is contained within the ac142 open reading frame. Different deletion mutants of this region showed that the integrity of the ac142-ac143 core gene cluster was required for the bacmids to display wild-type patterns of viral replication, BV production and RNA transcription

Development of AC-DC power system simulator

International Nuclear Information System (INIS)

Ichikawa, Tatsumi; Ueda, Kiyotaka; Inoue, Toshio

1984-01-01

A modeling and realization technique is described for realtime plant dynamics simulation of nuclear power generating unit in AC-DC power system simulator. Dynamic behavior of reactor system and steam system is important for investigation a further adequate unit control and protection system to system faults in AC and DC power system. Each unit of two nuclear power generating unit in the power system simulator consists of micro generator, DC motors, flywheels and process computer. The DC motor and flywheel simulates dynamic characteristics of steam turbine, and process computer simulates plant dynamics by digital simulation. We have realized real-time plant dynamics simulation by utilizing a high speed process I/O and a high speed digital differential analyzing processor (DDA) in which we builted a newly developed simple plant model. (author)

DC Vs AC - War Of Currents For Future Power Systems A HVDC Technology Overview

Directory of Open Access Journals (Sweden)

Anil K. Rai

2015-08-01

Full Text Available DC vs AC discussion began in 1880s with development of first commercial power transmission in Wall Street New York. Later when AC technology came into notice by efforts of inventor and researcher Sir Nicola Tesla soon the advantages of AC transmission and AC devices overtook the DC technology. It was hoped that DC technology had lost battle of currents. Today with researches going on FACTS devices and bulk power transmission HVDC has again gained a reputation in power sector. Solution of this centuries old debate is to develop HVDC systems that assists HVAC systems for better performance stability and control

Emergency ac power systems operating experience at U.S. nuclear power plants - 1976 through 1983

Energy Technology Data Exchange (ETDEWEB)

Battle, R. E. [Oak Ridge National Laboratory, Oak Ridge, Tennessee (United States)

1986-02-15

Success and failure data of test and emergency starts of emergency ac power sources (diesel generators) at U.S. nuclear power plants were collected and evaluated to estimate diesel generator reliability parameters. A regression analysis of the estimates of the probability of failure to start based on surveillance test data from 1976 through 1983 indicates that the probability of failure to start has been decreasing. However, the reliability of diesel generator performance during losses of off-site power for 1981 through 1983 was less than expected based on the test data estimates. The failures that occurred during losses of off-site power were reviewed to determine why the calculated failure to start was greater than expected, and possible explanations for this high value are presented. The subsystems involved In diesel generator subsystem failures were categorized to determine whether there were any dominant failure modes. The results indicate that further significant Improvement in diesel generator reliability will require improvement of many subsystems. (author)

High voltage AC/AC electrochemical capacitor operating at low temperature in salt aqueous electrolyte

Science.gov (United States)

Abbas, Qamar; Béguin, François

2016-06-01

We demonstrate that an activated carbon (AC)-based electrochemical capacitor implementing aqueous lithium sulfate electrolyte in 7:3 vol:vol water/methanol mixture can operate down to -40 °C with good electrochemical performance. Three-electrode cell investigations show that the faradaic contributions related with hydrogen chemisorption in the negative AC electrode are thermodynamically unfavored at -40 °C, enabling the system to work as a typical electrical double-layer (EDL) capacitor. After prolonged floating of the AC/AC capacitor at 1.6 V and -40°C, the capacitance, equivalent series resistance and efficiency remain constant, demonstrating the absence of ageing related with side redox reactions at this temperature. Interestingly, when temperature is increased back to 24 °C, the redox behavior due to hydrogen storage reappears and the system behaves as a freshly prepared one.

Final design of the Korean AC/DC converters for the ITER coil power supply system

Energy Technology Data Exchange (ETDEWEB)

Oh, Jong-Seok, E-mail: jsoh@nfri.re.kr [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Choi, Jungwan; Suh, Jae-Hak; Choi, Jihyun [ITER Korea, National Fusion Research Institute, Daejeon 305-806 (Korea, Republic of); Lee, Lacksang; Kim, Changwoo; Park, Hyungjin; Jo, Seongman; Lee, Seungyun; Hwang, Kwangcheol; Liu, Hyoyol [Dawonsys Corp., Siheung 429-450 (Korea, Republic of); Hong, Ki-Don; Sim, Dong-Joon; Lee, Jang-Soo [Hyosung Corp., Gongdeok-Dong, Seoul 121-720 (Korea, Republic of); Lee, Eui-Jae; Kwon, Yang-Hae; Lee, Dae-Yeol; Ko, Ki-Won; Kim, Jong-Min [Mobiis Corp., Yangjae-dong, Seoul 137-888 (Korea, Republic of); Song, Inho [ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 St. Paul Lez Durance Cedex (France); and others

2015-10-15

The final design of the ITER TF, CS, CC and VS AC/DC converters has been completed to implement ITER requirements following the detailed design and refinements of the preliminary design. The number of parallel thyristors and the rating of fuses are coordinated to keep those devices within the explosion limit even under most severe fault conditions. The impedance of the converter transformer has been optimized taking into account the energization inrush current, short circuit current, reactive power consumption and the available DC voltage. To ensure system integrity, AC/DC converters are mechanically divided into transformers, AC busbars, 6-pulse bridges, DC interconnecting busbars and DC reactors, and then all subsystems are decoupled by flexible links. To provide stable real time network communication down to the converters, a one GbE link is deployed between master controllers and local controllers. IEEE 1588 is implemented to the embedded controllers for precision time synchronization. This paper describes the detailed solutions implemented in the final design for the ITER AC/DC converters with R&D results of converter prototypes.

AcEST: DK954361 [AcEST

Lifescience Database Archive (English)

Full Text Available in 5-4 OS=Homo sap... 33 1.1 sp|Q9DBY1|SYVN1_MOUSE E3 ubiquitin-protein ligase synoviolin OS=... 33 1.4 sp|Q...86TM6|SYVN1_HUMAN E3 ubiquitin-protein ligase synoviolin OS=... 33 1.4 sp|O55188|DMP1_MOUSE Dentin matrix ac

21 CFR 886.4440 - AC-powered magnet.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered magnet. 886.4440 Section 886.4440 Food... DEVICES OPHTHALMIC DEVICES Surgical Devices § 886.4440 AC-powered magnet. (a) Identification. An AC-powered magnet is an AC-powered device that generates a magnetic field intended to find and remove...

R744 air conditioner with stop/start air conditioning, parking air conditioning and heat pump function in the ''COMET'' test car; R744-Klimaanlage mit Stopp/Start- und Standklimatisierung sowie Waermepumpenfunktion im Versuchstraeger ''COMET''

Energy Technology Data Exchange (ETDEWEB)

Brandes, H.; Horstmann, P.; Kneifel, M.; Hohl, R. [Robert Bosch GmbH, Schwieberdingen (Germany)

2006-07-01

Within a several years development project Robert Bosch GmbH has setup a test vehicle to investigate an integral energy management concept (COMET - Control of Mechanical, Electrical and Thermal Power). Key feature of the COMET vehicle concept is the hybrid drive train comprising the standard combustion engine and two electrical motors - each with 8 kW - being integrated in the power splitting Dual-E gearbox. Directly via the gearbox the compressor of the CO{sub 2} A/C system is driven so that an electrically parking and start-stop air condition and heating function using a CO{sub 2} heat pump can be realized. System setup, Cool down and heating up tests are shown and discussed. (orig.)

Efficacy of low level electric current (A-C) for controlling quagga mussles in the Welland Canal

Energy Technology Data Exchange (ETDEWEB)

Fears, C. [Delta Applied Technology, Inc., Pittsburgh, PA (United States); Mackie, G.L. [Water Systems Analysts, Guelph, Ontario (Canada)

1995-06-01

The efficacy of systems (for which patents are pending) which use low-voltage A-C currents for preventing settlement and attachment by zebra mussels were tested with steel rods and plates placed near the intake of a pulp and paper plant in the Welland Canal at Thorold, Ontario. Six racks made of 16 ft. (4.9 m), 2x4s (5.1 x 10.2 cm) were placed into the Welland Canal on August 5, 1994. One rack had 1/8th in (3.2 mm) diam x 12 in (30.5 cm) long steel rods, each separated by 2 in (5.1 cm) attached to pressure treated wood and concrete blocks and an A-C current of 16 v (or 8 v/in); rack 2 had steel rods of the same configuration but 12 v (or 6 v/in) was applied; rack 3 was identical to these but no current was applied and was used as a rod control. The remaining three racks had steel plates, each plate being 3 in (7.6 cm) wide X 24 in (61 cm) long X 1/4 in (6.4 mm) thick and separated by 2 in (5.1 cm); one had 12 v applied (or 6 v/in), another had 16 v applied (or 8 v/in), and the third had no current and was used as a plate control. The racks were placed on the upstream and downstream side of the intake at a depth of about 7 ft (2.1 m) where the mussels populations were heaviest (as determined by SCUBA diving). All mussels were quagga mussels (Dreissena bugensis). The racks were pulled in mid November after settlement was complete and the results showed: (1) complete prevention of settlement of both new recruits and translocators at 8 volts/in with steel rods on both wood and concrete surfaces and with steel plate trash bars; (2) partial prevention of settlement at 6 volts/in with steel rods on both wood and concrete surfaces and steel plates; and (3) that, at current kilowatt hr rates, total efficacy at 8 volts/in would cost approximately $10.80/day/1000 sq ft using rods to protect concrete walls and about $16.32/day/1000 sq ft to protect 3 in wide x 1/4 in thick trash bars. These costs can be reduced even further with pulse dosed AC currents.

Effects of AC Electric Field on Small Laminar Nonpremixed Flames

KAUST Repository

Xiong, Yuan

2015-01-01

Electric field can be a viable method in controlling various combustion properties. Comparing to traditional actuators, an application of electric field requires very small power consumption. Especially, alternating current (AC) has received

Application of a Self-recurrent Wavelet Neural Network in the Modeling and Control of an AC Servo System

Directory of Open Access Journals (Sweden)

Run Min HOU

2014-05-01

Full Text Available To control the nonlinearity, widespread variations in loads and time varying characteristic of the high power ac servo system, the modeling and control techniques are studied here. A self-recurrent wavelet neural network (SRWNN modeling scheme is proposed, which successfully addresses the issue of the traditional wavelet neural network easily falling into local optimum, and significantly improves the network approximation capability and convergence rate. The control scheme of a SRWNN based on fuzzy compensation is expected. Gradient information is provided in real time for the controller by using a SRWNN identifier, so as to ensure that the learning and adjusting function of the controller of the SRWNN operate well, and fuzzy compensation control is applied to improve rapidity and accuracy of the entire system. Then the Lyapunov function is utilized to judge the stability of the system. The experimental analysis and comparisons with other modeling and control methods, it is clearly shown that the validities of the proposed modeling scheme and control scheme are effective.

Automated start-up of EBR-II

International Nuclear Information System (INIS)

Kisner, R.A.

1989-01-01

Oak Ridge National Laboratory (ORNL) and Argonne National Laboratory (ANL) are undertaking a joint project to develop control philosophies, strategies, and algorithms for computer control of the start-up mode of the Experimental Breeder Reactor II (EBR-II). The major objective of this project is to show that advanced liquid-metal reactor (LMR) plants can be operated from low power to full power using computer control. Development of an automated control system with this objective in view will help resolve specific issues and provide proof through demonstration that automatic control for plant start-up is feasible. This paper describes the approach that will be used to develop such a system and some of the features it is expected to have. Structured, rule-based methods, which will provide start-up capability from a variety of initial plant conditions and degrees of equipment operability, will be used for accomplishing mode changes during plant start-up. Several innovative features will be incorporated such as signal, command, and strategy validation to maximize reliability, flexibility to accommodate a wide range of plant conditions, and overall utility. Continuous control design will utilize figures of merit to evaluate how well the controller meets the mission requirements. The operator interface will have unique ''look ahead'' features to let the operator see what will happen next. 15 refs., 7 figs., 1 tab

Progress on advanced dc and ac induction drives for electric vehicles

Science.gov (United States)

Schwartz, H. J.

1982-01-01

Progress is reported in the development of complete electric vehicle propulsion systems, and the results of tests on the Road Load Simulator of two such systems representative of advanced dc and ac drive technology are presented. One is the system used in the DOE's ETV-1 integrated test vehicle which consists of a shunt wound dc traction motor under microprocessor control using a transistorized controller. The motor drives the vehicle through a fixed ratio transmission. The second system uses an ac induction motor controlled by transistorized pulse width modulated inverter which drives through a two speed automatically shifted transmission. The inverter and transmission both operate under the control of a microprocessor. The characteristics of these systems are also compared with the propulsion system technology available in vehicles being manufactured at the inception of the DOE program and with an advanced, highly integrated propulsion system upon which technology development was recently initiated.

Food safety assessment of Cry8Ka5 mutant protein using Cry1Ac as a control Bt protein.

Science.gov (United States)

Farias, Davi Felipe; Viana, Martônio Ponte; Oliveira, Gustavo Ramos; Santos, Vanessa Olinto; Pinto, Clidia Eduarda Moreira; Viana, Daniel Araújo; Vasconcelos, Ilka Maria; Grossi-de-Sa, Maria Fátima; Carvalho, Ana Fontenele Urano

2015-07-01

Cry8Ka5 is a mutant protein from Bacillus thuringiensis (Bt) that has been proposed for developing transgenic plants due to promising activity against coleopterans, like Anthonomus grandis (the major pest of Brazilian cotton culture). Thus, an early food safety assessment of Cry8Ka5 protein could provide valuable information to support its use as a harmless biotechnological tool. This study aimed to evaluate the food safety of Cry8Ka5 protein following the two-tiered approach, based on weights of evidence, proposed by ILSI. Cry1Ac protein was used as a control Bt protein. The history of safe use revealed no convincing hazard reports for Bt pesticides and three-domain Cry proteins. The bioinformatics analysis with the primary amino acids sequence of Cry8Ka5 showed no similarity to any known toxic, antinutritional or allergenic proteins. The mode of action of Cry proteins is well understood and their fine specificity is restricted to insects. Cry8Ka5 and Cry1Ac proteins were rapidly degraded in simulated gastric fluid, but were resistant to simulated intestinal fluid and heat treatment. The LD50 for Cry8Ka5 and Cry1Ac was >5000 mg/kg body weight when administered by gavage in mice. Thus, no expected relevant risks are associated with the consumption of Cry8Ka5 protein. Copyright © 2015 Elsevier Ltd. All rights reserved.

Construction and characterisation of near-isogenic Plutella xylostella (Lepidoptera: Plutellidae) strains resistant to Cry1Ac toxin.

Science.gov (United States)

Zhu, Xun; Lei, Yanyuan; Yang, Yanjv; Baxter, Simon W; Li, Jianhong; Wu, Qingjun; Wang, Shaoli; Xie, Wen; Guo, Zhaojiang; Fu, Wei; Zhang, Youjun

2015-02-01

Resistance to insecticidal Bacillus thuringiensis (Bt) toxins has arisen in multiple populations of the worldwide Brassica pest Plutella xylostella (L.). To help elucidate the mechanism of resistance to Bt Cry1Ac toxin in a population from Florida, two pairs of near-isogenic lines (NILs) were developed. NILs were generated using either backcross or recombinant inbred line methodologies and evaluated for near-isogenicity with inter-simple-sequence-repeat (ISSR) markers. Backcross line BC6F4 maintained a similar level of Cry1Ac resistance to parental strain DBM1Ac-R (>5000-fold) yet showed 98.24% genetic similarity to the susceptible parental strain DBM1Ac-S. Single-pair backcrosses between DBM1Ac-S and BC6F4 revealed that Cry1Ac resistance was controlled by one recessive autosomal locus. BC6F4 exhibited high levels of cross-resistance to Cry1Ab and Cry1Ah but not to Cry1Ca or Cry1Ie. Near-isogenic strains were constructed to provide a reliable biological system to investigate the mechanism of Cry1Ac resistance in P. xylostella. These data suggest that resistance to Cry1Ac, Cry1Ab and Cry1Ah is probably caused by the alteration of a common receptor not recognised by Cry1Ca or Cry1Ie. Understanding Bt toxin cross-resistance provides valuable information to consider when developing pest control strategies to delay resistance evolution. © 2014 Society of Chemical Industry. © 2014 Society of Chemical Industry.

Test facility for auxiliary cooling system (ACS) of fast breeder reactor for Power Reactor and Nuclear Fuel Development Corporation (PNC)

International Nuclear Information System (INIS)

1983-01-01

In preparation of constructing ''Monju'', a prototype fast breeder reactor, PNC has been pushing forward its research and development projects and the ACS was constructed under these projects. The auxiliary cooling system is an important engineered safety feature, and is used for safe removal of heat from the reactor at the shutdown. The ACS serves as a means of testing and assessing the auxiliary cooling system for the ''Monju'' and is designed and manufactured to have one fifth capacity of the Monju. The air heat exchanger and the ACS system was designed to withstand higher temperature range of the conventional design code (MITI-501), and finned tubes were applied for effective heat removal. Preheating system was designed to heat up the whole system over 200 0 C within 20 hours to prevent sodium from freezing. Basic performance of ACS was verified satisfactorily by a series of performance tests, such as start up test, flow rate measurement and preheating test before delivery. The experience from designing and construction of ACS and data obtained by these tests will be very instructive for designing and construction of the ''Monju''. (author)

Financial planning and control in very small start-up companies: antecedents and effects on company performance

NARCIS (Netherlands)

Mengel, S.; Wouters, M.

2015-01-01

This study motivates and tests hypotheses about the antecedents of the use of financial planning and control systems in very small and young start-up firms, and, in turn, the effect of this on firm performance. This setting is of particular interest since theory on financial planning and control in

Study of Power Flow Algorithm of AC/DC Distribution System including VSC-MTDC

Directory of Open Access Journals (Sweden)

Haifeng Liang

2015-08-01

Full Text Available In recent years, distributed generation and a large number of sensitive AC and DC loads have been connected to distribution networks, which introduce a series of challenges to distribution network operators (DNOs. In addition, the advantages of DC distribution networks, such as the energy conservation and emission reduction, mean that the voltage source converter based multi-terminal direct current (VSC-MTDC for AC/DC distribution systems demonstrates a great potential, hence drawing growing research interest. In this paper, considering losses of the reactor, the filter and the converter, a mathematical model of VSC-HVDC for the load flow analysis is derived. An AC/DC distribution network architecture has been built, based on which the differences in modified equations of the VSC-MTDC-based network under different control modes are analyzed. In addition, corresponding interface functions under five control modes are provided, and a back/forward iterative algorithm which is applied to power flow calculation of the AC/DC distribution system including VSC-MTDC is proposed. Finally, by calculating the power flow of the modified IEEE14 AC/DC distribution network, the efficiency and validity of the model and algorithm are evaluated. With various distributed generations connected to the network at appropriate locations, power flow results show that network losses and utilization of transmission networks are effectively reduced.

Targeted α-Therapy of Metastatic Castration-Resistant Prostate Cancer with 225Ac-PSMA-617: Swimmer-Plot Analysis Suggests Efficacy Regarding Duration of Tumor Control.

Science.gov (United States)

Kratochwil, Clemens; Bruchertseifer, Frank; Rathke, Hendrik; Hohenfellner, Markus; Giesel, Frederik L; Haberkorn, Uwe; Morgenstern, Alfred

2018-05-01

The aim of this evaluation was to identify the first indicators of efficacy for 225 Ac-labeled prostate-specific membrane antigen (PSMA)-617 therapy in a retrospectively analyzed group of patients. Methods: Forty patients with metastatic castration-resistant prostate cancer were selected for treatment with three 100 kBq/kg cycles of 225 Ac-PSMA-617 at 2-mo intervals. Prostate-specific antigen (PSA) and blood cell count were measured every 4 wk. PSMA PET/CT or PSMA SPECT/CT were used for baseline staging and imaging follow-up at month 6. Follow-up included the duration of PSA response and radiologic progression-free survival at month 6. Patient histories were reviewed for the duration of previous treatment lines, and a swimmer plot was used to intraindividually compare the duration of tumor control by PSMA therapy versus prior treatment modalities. Results: Thirty-one of 40 patients were treated per protocol. Five patients discontinued treatment because of nonresponse, and 4 because of xerostomia. Of the 38 patients surviving at least 8 wk, 24 (63%) had a PSA decline of more than 50%, and 33 (87%) had a PSA response of any degree. The median duration of tumor control under 225 Ac-PSMA-617 last-line therapy was 9.0 mo; 5 patients had an enduring response of more than 2 y. Because all patients had advanced disease, this result compares favorably with the tumor control rates associated with earlier-phase disease; the most common preceding first-, second-, third-, and fourth-line therapies were abiraterone (median duration 10.0 mo), docetaxel (6.5 mo), enzalutamide (6.5 mo), and cabazitaxel (6.0 mo), respectively. Conclusion: A positive response for surrogate parameters demonstrates remarkable antitumor activity for 225 Ac-PSMA-617. Swimmer-plot analysis indicates a promising duration of tumor control, especially considering the unfavorable prognostic profile of the selected advanced-stage patients. Xerostomia was the main reason patients discontinued therapy or refused

Random-start GnRH antagonist for emergency fertility preservation: a self-controlled trial

Directory of Open Access Journals (Sweden)

Checa MA

2015-02-01

Full Text Available Miguel A Checa,1,2 Mario Brassesco,2 Margalida Sastre,1 Manuel Gómez,2 Julio Herrero,3 Laura Marque,3 Arturo Brassesco,2 Juan José Espinós3 1Department of Obstetrics and Gynecology, Parc de Salut Mar, Universitat Autònoma de Barcelona, 2Centro de Infertilidad y Reproducción Humana (CIRH, 3Centro de Reproducción Asistida Sagrada Familia, Clínica Sagrada Familia, Barcelona, Spain Abstract: The aim of this study is to evaluate the feasibility and safety of random-start controlled ovarian hyperstimulation (COH for emergency fertility preservation, regardless of the phase of the menstrual cycle. A self-controlled pilot clinical trial (NCT01385332 was performed in an acute-care teaching hospital and in two private reproductive centers in Barcelona, Spain. Eleven egg donors participated in the study. Two random-start gonadotropin-releasing hormone (GnRH antagonist protocols were assessed in which ganirelix was initiated on either day 10 (protocol B or on day 20 (protocol C of the menstrual cycle and was continued until estradiol levels were below 60 pg/dL. These protocols were compared with a standard protocol (protocol A. The main outcome of interest was the number of metaphase 2 oocytes retrieved. Results from this study show that the number of mature oocytes retrieved was comparable across the different protocols (14.3±4.6 in the standard protocol versus 13.0±9.1 and 13.2±5.2 in protocols B and C, respectively; values expressed as mean ± standard deviation. The mean number of days needed for a GnRH antagonist to lower estradiol levels, as well as the ongoing pregnancy rates, were also similar when protocols B (stimulation in follicular phase and C (stimulation on luteal phase were compared with protocol A (standard stimulation. GnRH antagonists can be effectively used for random-start controlled ovarian hyperstimulation with an ovarian response similar to that of standard protocols, and the antagonists appear suitable for emergency

Max Launch Abort System (MLAS) Pad Abort Test Vehicle (PATV) II Attitude Control System (ACS) Integration and Pressurization Subsystem Dynamic Random Vibration Analysis

Science.gov (United States)

Ekrami, Yasamin; Cook, Joseph S.

2011-01-01

In order to mitigate catastrophic failures on future generation space vehicles, engineers at the National Aeronautics and Space Administration have begun to integrate a novel crew abort systems that could pull a crew module away in case of an emergency at the launch pad or during ascent. The Max Launch Abort System (MLAS) is a recent test vehicle that was designed as an alternative to the baseline Orion Launch Abort System (LAS) to demonstrate the performance of a "tower-less" LAS configuration under abort conditions. The MLAS II test vehicle will execute a propulsive coast stabilization maneuver during abort to control the vehicles trajectory and thrust. To accomplish this, the spacecraft will integrate an Attitude Control System (ACS) with eight hypergolic monomethyl hydrazine liquid propulsion engines that are capable of operating in a quick pulsing mode. Two main elements of the ACS include a propellant distribution subsystem and a pressurization subsystem to regulate the flow of pressurized gas to the propellant tanks and the engines. The CAD assembly of the Attitude Control System (ACS) was configured and integrated into the Launch Abort Vehicle (LAV) design. A dynamic random vibration analysis was conducted on the Main Propulsion System (MPS) helium pressurization panels to assess the response of the panel and its components under increased gravitational acceleration loads during flight. The results indicated that the panels fundamental and natural frequencies were farther from the maximum Acceleration Spectral Density (ASD) vibrations which were in the range of 150-300 Hz. These values will direct how the components will be packaged in the vehicle to reduce the effects high gravitational loads.

Simultaneous distribution of AC and DC power

Science.gov (United States)

Polese, Luigi Gentile

2015-09-15

A system and method for the transport and distribution of both AC (alternating current) power and DC (direct current) power over wiring infrastructure normally used for distributing AC power only, for example, residential and/or commercial buildings' electrical wires is disclosed and taught. The system and method permits the combining of AC and DC power sources and the simultaneous distribution of the resulting power over the same wiring. At the utilization site a complementary device permits the separation of the DC power from the AC power and their reconstruction, for use in conventional AC-only and DC-only devices.

Isolation of MA-ACS Gene Family and Expression Study of MA-ACS1 Gene in Musa acuminata Cultivar Pisang Ambon Lumut

Directory of Open Access Journals (Sweden)

LISTYA UTAMI KARMAWAN

2009-03-01

Full Text Available Musa acuminata cultivar pisang ambon lumut is a native climacteric fruit from Indonesia. Climacteric fruit ripening process is triggered by the gaseous plant hormone ethylene. The rate limiting enzyme involved in ethylene biosynthesis is ACC synthase (ACS which is encoded by ACS gene family. The objective of this study is to identify MA-ACS gene family in M. acuminata cultivar pisang ambon lumut and to study the MA-ACS1 gene expression. The result showed that there were nine M. acuminata ACS gene family members called MA-ACS1–9. Two of them (MA-ACS1 and MA-ACS2 were assessed using reverse transcriptase PCR (RT-PCR for gene expression study and it was only MA-ACS1 correlated with fruit ripening. The MA-ACS1 gene fragment has been successfully isolated and characterized and it has three introns, four exons, and one stop codon. It also shows highest homology with MACS1 gene from M. acuminata cultivar Hsian Jien Chiao (GenBank accession number AF056164. Expression analysis of MA-ACS1 using quantitative PCR (qPCR showed that MA-ACS1 gene expression increased significantly in the third day, reached maximum at the fifth day, and then decreased in the seventh day after harvesting. The qPCR expression analysis result correlated with the result of physical analysis during fruit ripening.

Universality of ac conduction in disordered solids

DEFF Research Database (Denmark)

Dyre, Jeppe; Schrøder, Thomas

2000-01-01

The striking similarity of ac conduction in quite different disordered solids is discussed in terms of experimental results, modeling, and computer simulations. After giving an overview of experiment, a macroscopic and a microscopic model are reviewed. For both models the normalized ac conductivity...... as a function of a suitably scaled frequency becomes independent of details of the disorder in the extreme disorder limit, i.e., when the local randomly varying mobilities cover many orders of magnitude. The two universal ac conductivities are similar, but not identical; both are examples of unusual non......-power-law universalities. It is argued that ac universality reflects an underlying percolation determining dc as well as ac conductivity in the extreme disorder limit. Three analytical approximations to the universal ac conductivities are presented and compared to computer simulations. Finally, model predictions...

The Start2Bike program is effective in increasing health-enhancing physical activity: a controlled study

Directory of Open Access Journals (Sweden)

Linda Ooms

2017-06-01

Full Text Available Abstract Background The sports club is seen as a new relevant setting to promote health-enhancing physical activity (HEPA among inactive population groups. Little is known about the effectiveness of strategies and activities implemented in the sports club setting on increasing HEPA levels. This study investigated the effects of Start2Bike, a six-week training program for inactive adults and adult novice cyclers, on HEPA levels of participants in the Netherlands. Methods To measure physical activity, the Short QUestionnaire to ASsess Health-enhancing physical activity was used (SQUASH. Start2Bike participants were measured at baseline, six weeks and six months. A matched control group was measured at baseline and six months. The main outcome measure was whether participants met the Dutch Norm for Health-enhancing Physical Activity (DNHPA: 30 min of moderate-intensity activity on five days a week; Fit-norm (20 min of vigorous-intensity activity on three days a week; and Combi-norm (meeting the DNHPA and/or Fit-norm. Other outcome measures included: total minutes of physical activity per week; and minutes of physical activity per week per domain and intensity category. Statistical analyses consisted of McNemar tests and paired t-tests (within-group changes; and multiple logistic and linear regression analyses (between-group changes. Results In the Start2Bike group, compliance with Dutch physical activity norms increased significantly, both after six weeks and six months. Control group members did not alter their physical activity behavior. Between-group analyses showed that participants in the Start2Bike group were more likely to meet the Fit-norm at the six-month measurement compared to the control group (odds ratio = 2.5; 95% confidence interval (CI = 1.1–5.8, p = 0.03. This was due to the Start2Bike participants spending on average 193 min/week more in vigorous-intensity activities (b = 193; 95% CI = 94–293, p < 0.001 and 130�

Gas Turbine Engine Starting Applicated on TV2-117 Turboshaft

Directory of Open Access Journals (Sweden)

R. M. Catana

2017-10-01

Full Text Available The paper presents the examination of two different types of engine starting configurations, applicated on TV2-117A turboshaft, running into the test bench. The first type of starting configuration is a normal starting, with the engine connected to the dynamometer which controls the free turbine speed by the dynamometer load. The second type of starting is a different one, the engine is not connected with the dynamometer, therefore it results that there is no control of the free turbine speed from the dynamometer, only from the engine but in particular conditions. To achieve the starting phase an instrumentation scheme is created, to control and monitor the engine, and a starting sequence with all the parameters, confirmations and commands that are involved into the starting phase. The engine starting is performed by the test bench operating system, composed of an acquisition system and a programmable controller, wherewith is running the starting sequence.

An NPV and AC Analysis of a Stochastic Inventory System with Joint Manufacturing and Remanufacturing

NARCIS (Netherlands)

E.A. van der Laan (Erwin)

2000-01-01

textabstractWhile the net present value (NPV) approach is widely accepted as the right framework for studying production and inventory control systems, average cost (AC) models are more widely used. For the well known EOQ model it can be veri_ed that (under certain conditions) the AC approach gives

Pixel-based CTE Correction of ACS/WFC: Modifications To The ACS Calibration Pipeline (CALACS)

Science.gov (United States)

Smith, Linda J.; Anderson, J.; Armstrong, A.; Avila, R.; Bedin, L.; Chiaberge, M.; Davis, M.; Ferguson, B.; Fruchter, A.; Golimowski, D.; Grogin, N.; Hack, W.; Lim, P. L.; Lucas, R.; Maybhate, A.; McMaster, M.; Ogaz, S.; Suchkov, A.; Ubeda, L.

2012-01-01

The Advanced Camera for Surveys (ACS) was installed on the Hubble Space Telescope (HST) nearly ten years ago. Over the last decade, continuous exposure to the harsh radiation environment has degraded the charge transfer efficiency (CTE) of the CCDs. The worsening CTE impacts the science that can be obtained by altering the photometric, astrometric and morphological characteristics of sources, particularly those farthest from the readout amplifiers. To ameliorate these effects, Anderson & Bedin (2010, PASP, 122, 1035) developed a pixel-based empirical approach to correcting ACS data by characterizing the CTE profiles of trails behind warm pixels in dark exposures. The success of this technique means that it is now possible to correct full-frame ACS/WFC images for CTE degradation in the standard data calibration and reduction pipeline CALACS. Over the past year, the ACS team at STScI has developed, refined and tested the new software. The details of this work are described in separate posters. The new code is more effective at low flux levels (repair ACS electronics) and pixel-based CTE correction. In addition to the standard cosmic ray corrected, flat-fielded and drizzled data products (crj, flt and drz files) there are three new equivalent files (crc, flc and drc) which contain the CTE-corrected data products. The user community will be able to choose whether to use the standard or CTE-corrected products.

Chloroplast localization of Cry1Ac and Cry2A protein- an alternative way of insect control in cotton

Directory of Open Access Journals (Sweden)

Adnan Muzaffar

2015-01-01

Full Text Available BACKGROUND: Insects have developed resistance against Bt-transgenic plants. A multi-barrier defense system to weaken their resistance development is now necessary. One such approach is to use fusion protein genes to increase resistance in plants by introducing more Bt genes in combination. The locating the target protein at the point of insect attack will be more effective. It will not mean that the non-green parts of the plants are free of toxic proteins, but it will inflict more damage on the insects because they are at maximum activity in the green parts of plants. RESULTS: Successful cloning was achieved by the amplification of Cry2A, Cry1Ac, and a transit peptide. The appropriate polymerase chain reaction amplification and digested products confirmed that Cry1Ac and Cry2A were successfully cloned in the correct orientation. The appearance of a blue color in sections of infiltrated leaves after 72 hours confirmed the successful expression of the construct in the plant expression system. The overall transformation efficiency was calculated to be 0.7%. The amplification of Cry1Ac-Cry2A and Tp2 showed the successful integration of target genes into the genome of cotton plants. A maximum of 0.673 μg/g tissue of Cry1Ac and 0.568 μg/g tissue of Cry2A was observed in transgenic plants. We obtained 100% mortality in the target insect after 72 hours of feeding the 2nd instar larvae with transgenic plants. The appearance of a yellow color in transgenic cross sections, while absent in the control, through phase contrast microscopy indicated chloroplast localization of the target protein. CONCLUSION: Locating the target protein at the point of insect attack increases insect mortality when compared with that of other transgenic plants. The results of this study will also be of great value from a biosafety point of view.

MATHEMATICAL MODELING OF AC ELECTRIC POINT MOTOR

Directory of Open Access Journals (Sweden)

S. YU. Buryak

2014-03-01

Full Text Available Purpose. In order to ensure reliability, security, and the most important the continuity of the transportation process, it is necessary to develop, implement, and then improve the automated methods of diagnostic mechanisms, devices and rail transport systems. Only systems that operate in real time mode and transmit data on the instantaneous state of the control objects can timely detect any faults and thus provide additional time for their correction by railway employees. Turnouts are one of the most important and responsible components, and therefore require the development and implementation of such diagnostics system.Methodology. Achieving the goal of monitoring and control of railway automation objects in real time is possible only with the use of an automated process of the objects state diagnosing. For this we need to know the diagnostic features of a control object, which determine its state at any given time. The most rational way of remote diagnostics is the shape and current spectrum analysis that flows in the power circuits of railway automatics. Turnouts include electric motors, which are powered by electric circuits, and the shape of the current curve depends on both the condition of the electric motor, and the conditions of the turnout maintenance. Findings. For the research and analysis of AC electric point motor it was developed its mathematical model. The calculation of parameters and interdependencies between the main factors affecting the operation of the asynchronous machine was conducted. The results of the model operation in the form of time dependences of the waveform curves of current on the load on engine shaft were obtained. Originality. During simulation the model of AC electric point motor, which satisfies the conditions of adequacy was built. Practical value. On the basis of the constructed model we can study the AC motor in various mode of operation, record and analyze current curve, as a response to various changes

Clinical significance of determination of serum hypersensitive C reactive protein (HS-CRP) levels in patients with acute coronary syndrome (ACS)

International Nuclear Information System (INIS)

Zhai Chunxi; Zhang Fengju; Wang Kejun

2005-01-01

Objective: To study the relationship between changes in serum HS-CRP levels and the status of atherosclerotic plaques in patients with ACS. Methods: Serum HS-CRP levels were measured in 35 patients with ACS at admission, 1 week and 1 month later as well as in 30 controls without recent infection. Results: HS-CRP levels in patients with ACS were significantly higher than those in the controls (P<0.01). The levels were highest at admission and fell gradually. Conclusion: HS-CRP could be a marker reflecting the status of atherosclerotic plaques in patients with ACS. (authors)

AcMNPV

African Journals Online (AJOL)

USER

2010-08-16

Aug 16, 2010 ... biosynthesis pathway and plays an important role in insect growth and .... Construction and propagation of recombined AcMNPV. The recombined ... infected by virus increased with incubation time (Figure. 3). The growth of ...

Propiedades acústicas de los paneles de carrizo

Directory of Open Access Journals (Sweden)

Díaz, César

2012-03-01

Full Text Available Reed is a plant species very similar to common cane which is widespread all over the Earth. It is an ecological and sustainable material which is low-cost, aesthetically attractive, easy to obtain and install, and can be used in different construction systems. This work analyses the acoustic properties of reed panels from the point of view of sound absorption and sound insulation against airborne noise, according to the corresponding EN ISO standards. The experimental results obtained point to the conclusion that reed panels are suitable construction systems for controlling reverberant sound within a space, and that the sound reduction index values for different thicknesses of reed panels, or reed panels used in combination with wood particle boards, demonstrate the possibility of using them in construction as an element on the facades and roofs of buildings and for interior partitions.

El carrizo es una especie vegetal, parecida a la caña común, que se encuentra ampliamente distribuida en la superficie terrestre. Es un material ecológico y sostenible de bajo coste, estéticamente aceptable, fácil de obtener y colocar, que permite generar diferentes sistemas constructivos. En este trabajo se analizan las propiedades acústicas de los paneles de carrizo en lo referente a la absorción acústica y al aislamiento acústico a ruido aéreo, para ello se han aplicado los procedimientos de las normas EN ISO correspondientes. De los resultados experimentales obtenidos se concluye que los paneles de carrizo son unos sistemas constructivos adecuados para el control del sonido reverberante en un recinto y que los valores del índice de reducción acústica de paneles de diferentes espesores o en combinación con tableros de partículas de madera muestran la posibilidad de utilizarlos en la edificación como elemento de fachada, en cubiertas de edificios y particiones interiores.

New three-phase ac-ac converter incorporating three-phase boost integrated ZVT bridge and single-phase HF link

International Nuclear Information System (INIS)

Abdelhamid, Tamer H.; Sabzali, Ahmad J.

2008-01-01

This paper presents a new zero voltage transition (ZVT), power factor corrected three phase ac-ac converter with single phase high frequency (HF) link. It is a two stage converter; the first stage is a boost integrated bridge converter (combination of a 3 ph boost converter and a bridge converter) operated at fixed frequency and that operates in two modes at ZVT for all switches and establishes a 1 ph square wave HF link. The second stage is a bi-directional pulse width modulation (PWM) 3 ph bridge that converts the 1 ph HF link to a 3 ph voltage using a novel switching strategy. The converter modes of operation and key equations are outlined. Simulation of the overall system is conducted using Simulink. The switching strategy and its corresponding control circuit are clearly described. Experimental verification of the simulation is conducted for a prototype of 100 V, 500 W at 10 kHz link frequency

Autonomous power management for interlinked AC-DC microgrids

DEFF Research Database (Denmark)

Nutkani, Inam Ullah; Meegahapola, Lasantha; Andrew, Loh Poh Chiang

2018-01-01

of the DC micro-grid before importing power from the interlinked AC microgrid. This strategy enables voltage regulation in the DC microgrid, and also reduces the number of converters in operation. The proposed scheme is fully autonomous while it retains the plug-n-play features for generators and tie......The existing power management schemes for inter-linked AC-DC microgrids have several operational drawbacks. Some of the existing control schemes are designed with the main objective of sharing power among the interlinked microgrids based on their loading conditions, while other schemes regulate...... the voltage of the interlinked microgrids without considering the specific loading conditions. However, the existing schemes cannot achieve both objectives efficiently. To address these issues, an autonomous power management scheme is proposed, which explicitly considers the specific loading condition...

Engineering cotton (Gossypium hirsutum L.) for resistance to cotton leaf curl disease using viral truncated AC1 DNA sequences.

Science.gov (United States)

Hashmi, Jamil A; Zafar, Yusuf; Arshad, Muhammad; Mansoor, Shahid; Asad, Shaheen

2011-04-01

Several important biological processes are performed by distinct functional domains found on replication-associated protein (Rep) encoded by AC1 of geminiviruses. Two truncated forms of replicase (tAC1) gene, capable of expressing only the N-terminal 669 bp (5'AC1) and C-terminal 783 bp (3'AC1) nucleotides cloned under transcriptional control of the CaMV35S were introduced into cotton (Gossypium hirsutum L.) using LBA4404 strain of Agrobacterium tumefaciens to make use of an interference strategy for impairing cotton leaf curl virus (CLCuV) infection in transgenic cotton. Compared with nontransformed control, we observed that transgenic cotton plants overexpressing either N-terminal (5'AC1) or C-terminal (3'AC1) sequences confer resistance to CLCuV by inhibiting replication of viral genomic and β satellite DNA components. Molecular analysis by Northern blot hybridization revealed high transgene expression in early and late growth stages associated with inhibition of CLCuV replication. Of the eight T(1) transgenic lines tested, six had delayed and minor symptoms as compared to nontransformed control lines which developed disease symptoms after 2-3 weeks of whitefly-mediated viral delivery. Virus biological assay and growth of T(2) plants proved that transgenic cotton plants overexpressing 5'- and 3'AC1 displayed high resistance level up to 72, 81%, respectively, as compared to non-transformed control plants following inoculation with viruliferous whiteflies giving significantly high cotton seed yield. Progeny analysis of these plants by polymerase chain reaction (PCR), Southern blotting and virus biological assay showed stable transgene, integration, inheritance and cotton leaf curl disease (CLCuD) resistance in two of the eight transgenic lines having single or two transgene insertions. Transgenic cotton expressing partial AC1 gene of CLCuV can be used as virus resistance source in cotton breeding programs aiming to improve virus resistance in cotton crop.

Approaches to building single-stage AC/AC conversion switch-mode audio power amplifiers

Energy Technology Data Exchange (ETDEWEB)

Ljusev, P.; Andersen, Michael A.E.

2005-07-01

This paper discusses the possible topologies and promising approaches towards direct single-phase AC-AC conversion of the mains voltage for audio applications. When compared to standard Class-D switching audio power amplifiers with a separate power supply, it is expected that direct conversion will provide better efficiency and higher level of integration, leading to lower component count, volume and cost, but at the expense of a minor performance deterioration. (au)

Active Power Regulation based on Droop for AC Microgrid

DEFF Research Database (Denmark)

Li, Chendan; Coelho, Ernane A. A.; Firoozabadi, Mehdi Savaghebi

2015-01-01

In this paper, two different control strategies are proposed to address the active power regulation issue in AC microgrids. The principle of power regulation in the droop controller is firstly introduced. Frequency scheduling and droop gain scheduling on top of droop control is proposed...... to successfully follow the active power command. The limitation of each method is discussed in term of small signal stability and light load sharing, respectively. Discussion on the effects of power command is also given. The simulation is carried out for both the strategies to verify the active power control...

Low ac loss geometries in YBCO coated conductors

International Nuclear Information System (INIS)

Duckworth, R.C.; List, F.A.; Paranthaman, M.P.; Rupich, M.W.; Zhang, W.; Xie, Y.Y.; Selvamanickam, V.

2007-01-01

Reduction of ac losses in applied ac fields can be accomplished through either the creation of filaments and bridging in YBCO coated conductors or by an assembly of narrow width YBCO tapes. The ac losses for each of these geometries were measured at 77 K in perpendicular ac fields up to 100 mT. Despite physical isolation of the filaments, coupling losses were still present in the samples when compared to the expected hysteretic loss. In addition to filamentary conductors the assembly of stacked YBCO conductor provides an alternative method of ac loss reduction. When compared to a 4-mm wide YBCO coated conductor with a critical current of 60 A, the ac loss in a stack of 2-mm wide YBCO coated conductors with a similar total critical current was reduced. While the reduction in ac loss in a 2-mm wide stack coincided with the reduction in the engineering current density of the conductor, further reduction of ac loss was obtained through the splicing of the 2-mm wide tapes with low resistance solders

Low ac loss geometries in YBCO coated conductors

Energy Technology Data Exchange (ETDEWEB)

Duckworth, R.C. [Oak Ridge National Laboratory, One Bethel Valley Road, P.O. Box 2008, MS-6305, Oak Ridge, TN 37831-6305 (United States)], E-mail: duckworthrc@ornl.gov; List, F.A.; Paranthaman, M.P. [Oak Ridge National Laboratory, One Bethel Valley Road, P.O. Box 2008, MS-6305, Oak Ridge, TN 37831-6305 (United States); Rupich, M.W.; Zhang, W. [American Superconductor, Two Technology Drive, Westborough, MA 01581 (United States); Xie, Y.Y.; Selvamanickam, V. [SuperPower, 450 Duane Ave, Schenectady, NY 12304 (United States)

2007-10-01

Reduction of ac losses in applied ac fields can be accomplished through either the creation of filaments and bridging in YBCO coated conductors or by an assembly of narrow width YBCO tapes. The ac losses for each of these geometries were measured at 77 K in perpendicular ac fields up to 100 mT. Despite physical isolation of the filaments, coupling losses were still present in the samples when compared to the expected hysteretic loss. In addition to filamentary conductors the assembly of stacked YBCO conductor provides an alternative method of ac loss reduction. When compared to a 4-mm wide YBCO coated conductor with a critical current of 60 A, the ac loss in a stack of 2-mm wide YBCO coated conductors with a similar total critical current was reduced. While the reduction in ac loss in a 2-mm wide stack coincided with the reduction in the engineering current density of the conductor, further reduction of ac loss was obtained through the splicing of the 2-mm wide tapes with low resistance solders.

Improvement of the dynamic performance of an AC linear permanent magnet machine

NARCIS (Netherlands)

Jansen, J.W.; Lomonova, E.; Vandenput, A.J.A.; Compter, J.C.; Verweij, A.H.

2003-01-01

This paper discusses the controller design and test approaches leading to the performance improvement of a brushless 3-phase AC synchronous permanent magnet linear machine. The feasible controller design concept for the linear machine is presented and further implemented in Simulink and dSPACE. Two

Integration of Xantrex HY-100 Hybrid Inverter with an AC Induction Wind Turbine

Energy Technology Data Exchange (ETDEWEB)

Corbus, D.; Newcomb, C.; Friedly, S.

2003-05-01

Several issues must be addressed before solid-state inverters can be used in wind-diesel systems with larger wind turbines. This project addresses those issues by using a commercial hybrid inverter designed for PV-diesel systems and modifying the inverter for use with an AC induction wind turbine. Another approach would have entailed building an inverter specifically for use with an AC induction wind turbine, but that was beyond the scope of this project. The inverter chosen for this project was a Xantrex HY-100, an inverter designed for PV systems. The unit consists of an inverter/rectifier bridge, a generator interface contactor, a battery charge controller, a hybrid controller, and the associated control electronics. Details of the inverter may be found in Appendix A. A twofold approach was taken to integrating the existing inverter for use with an AC induction wind turbine: 1) development of a detailed model to model both steady-state and transient behavior of the system, and 2) modification and testing of the inverter with an induction wind turbine based on the modeling results. This report describes these two tasks.

Wavelet-fuzzy speed indirect field oriented controller for three-phase AC motor drive – Investigation and implementation

Directory of Open Access Journals (Sweden)

Sanjeevikumar Padmanaban

2016-09-01

Full Text Available Three-phase voltage source inverter driven induction motor is used in many medium- and high-power applications. Precision in speed of the motor play vital role, i.e. popular methods of direct/indirect field-oriented control (FOC are applied. FOC is employed with proportional–integral (P-I or proportional–integral–derivative (P-I-D controllers and they are not adaptive, since gains are fixed at all operating conditions. Therefore, it needs a robust speed controlling in precision for induction motor drive application. This research paper articulates a novel speed control for FOC induction motor drive based on wavelet-fuzzy logic interface system. In specific, the P-I-D controller of IFOC which is actually replaced by the wavelet-fuzzy controller. The speed feedback (error signal is composed of multiple low and high frequency components. Further, these components are decomposed by the discrete wavelet transform and the fuzzy logic controller to generate the scaled gains for the indirect FOC induction motor. Complete model of the proposed ac motor drive is developed with numerical simulation Matlab/Simulink software and tested under different working conditions. For experimental verification, a hardware prototype was implemented and the control algorithm is framed using TMS320F2812 digital signal processor (dsp. Both simulation and hardware results presented in this paper are shown in close agreement and conformity about the suitability for industrial applications.

AC conductivity and dielectric behavior of bulk Furfurylidenemalononitrile

Science.gov (United States)

El-Nahass, M. M.; Ali, H. A. M.

2012-06-01

AC conductivity and dielectric behavior for bulk Furfurylidenemalononitrile have been studied over a temperature range (293-333 K) and frequency range (50-5×106 Hz). The frequency dependence of ac conductivity, σac, has been investigated by the universal power law, σac(ω)=Aωs. The variation of the frequency exponent (s) with temperature was analyzed in terms of different conduction mechanisms, and it was found that the correlated barrier hopping (CBH) model is the predominant conduction mechanism. The temperature dependence of σac(ω) showed a linear increase with the increase in temperature at different frequencies. The ac activation energy was determined at different frequencies. Dielectric data were analyzed using complex permittivity and complex electric modulus for bulk Furfurylidenemalononitrile at various temperatures.

Marker-assisted selection on E. coli F4ab/ac resistance and the effect on neonatal survival in piglets

DEFF Research Database (Denmark)

Jørgensen, Claus Bøttcher; Anderson, Susan I.; Cirera, Susanna

Enterotoxigenic Escherichia coli (ETEC) that express the F4ab or F4ac fimbriae (formerly known as K88ab/ac) are major causes of diarrhea and death in neonatal and young pigs. A locus controlling susceptibility towards ETEC F4ab/ac has previously been mapped to pig chromosome 13q41. A number...

Assay Methods for ACS Activity and ACS Phosphorylation by MAP Kinases In Vitro and In Vivo.

Science.gov (United States)

Han, Xiaomin; Li, Guojing; Zhang, Shuqun

2017-01-01

Ethylene, a gaseous phytohormone, has profound effects on plant growth, development, and adaptation to the environment. Ethylene-regulated processes begin with the induction of ethylene biosynthesis. There are two key steps in ethylene biosynthesis. The first is the biosynthesis of 1-aminocyclopropane-1-carboxylic acid (ACC) from S-Adenosyl-Methionine (SAM), a common precursor in many metabolic pathways, which is catalyzed by ACC synthase (ACS). The second is the oxidative cleavage of ACC to form ethylene under the action of ACC oxidase (ACO). ACC biosynthesis is the committing and generally the rate-limiting step in ethylene biosynthesis. As a result, characterizing the cellular ACS activity and understanding its regulation are important. In this chapter, we detail the methods used to measure, (1) the enzymatic activity of both recombinant and native ACS proteins, and (2) the phosphorylation of ACS protein by mitogen-activated protein kinases (MAPKs) in vivo and in vitro.

Software for physical start-up console

International Nuclear Information System (INIS)

Arbet, L.; Suchy, R.

1991-01-01

The physical start-up console comprises an PC AT-based control unit equipped with an 80386 processor, and information input/output units. The basic functions to be fulfilled by the control unit software include data acquisition related to the following parameters: neutron physics properties of the reactor core (neutron fluxes recorded by ionization chambers and reactivity recorded by a digital reactimeter), positions of the reactor core control elements (by the digital position meter) and reactor core control measurements, and technological quantities requisite for evaluating physical start-up tests. The measured and calculated data are shown on the control unit display. The setup of the data acquisition system and of user programs is dealt with, and characteristics of the user processes are briefly described. (Z.S.)

Design of Controller for Reducing In-Rush Current of Single-Phase Induction Motor

Energy Technology Data Exchange (ETDEWEB)

Park, Su Kang; Baek, Hyung Lae; Lee, Sang Il [Chosun University, Kwangju (Korea)

2001-05-01

During an AC motor's start-up accelerating period, a large amount of current is required to reach to the rating speed. This is called in-rush current. This peak in-rush current can be more than about several times the operating or steady-state current in the full load rating of the motor. In-rush current is present in both and electronic ballasts. The main area of concern is the tripping of circuit breaker and fuses which can affect electrical system components From this, we can see that the electrical power controllers will be rather concerned, since they have to supply the actual current necessary to start the motor. This paper presents a new method to reducing in-rush current and energy saving of the single-phase induction motor used in air-conditioner. It can be obtained that proposed system is low cost and small size as compared with other controller. Experiments are focused on a capacitor starting single-phase induction motor. The optimal power saving and in-rush current limiting by phase angle control are verified by experimental results. Also, auxiliary winding was controlled by electronic starting switch. (author). 10 refs., 13 figs., 2 tabs.

Application of intelligent soft start in asynchronous motor

Science.gov (United States)

Du, Xue; Ye, Ying; Wang, Yuelong; Peng, Lei; Zhang, Suying

2018-05-01

The starting way of three phase asynchronous motor has full voltage start and step-down start. Direct starting brings large current impact, causing excessive local temperature to the power grid and larger starting torque will also impact the motor equipment and affect the service life of the motor. Aim at the problem of large current and torque caused by start-up, an intelligent soft starter is proposed. Through the application of intelligent soft start on asynchronous motor, highlights its application advantage in motor control.

RNA interference suppression of mucin 5AC (MUC5AC reduces the adhesive and invasive capacity of human pancreatic cancer cells

Directory of Open Access Journals (Sweden)

Yamada Nobuya

2010-05-01

Full Text Available Abstract Background MUC5AC is a secretory mucin normally expressed in the surface muconous cells of stomach and bronchial tract. It has been known that MUC5AC de novo expression occurred in the invasive ductal carcinoma and pancreatic intraepithelial neoplasm with no detectable expression in normal pancreas, however, its function remains uncertain. Here, we report the impact of MUC5AC on the adhesive and invasive ability of pancreatic cancer cells. Methods We used two MUC5AC expressing cell lines derived from human pancreatic cancer, SW1990 and BxPC3. Small-interfering (si RNA directed against MUC5AC were used to assess the effects of MUC5AC on invasion and adhesion of pancreas cancer cells in vitro and in vivo. We compared parental cells (SW1990 and BxPC3 with MUC5AC suppressed cells by si RNA (si-SW1990 and si-BxPC3. Results MUC5AC was found to express in more than 80% of pancreatic ductal carcinoma specimens. Next we observed that both of si-SW1990 and si-BxPC3 showed significantly lower adhesion and invasion to extracellular matrix components compared with parental cell lines. Expression of genes associated with adhesion and invasion including several integerins, matrix metalloproteinase (MMP -3 and vascular endothelial growth factor (VEGF were down-regulated in both MUC5AC suppressed cells. Furthermore, production of VEGF and phosphorylation of VEGFR-1 were significantly reduced by MUC5AC down regulation. Both of si-SW1990 and si-BxPC3 attenuated activation of Erk1/2. In vivo, si-SW1990 did not establish subcutaneous tumor in nude mice. Conclusions Knockdown of MUC5AC reduced the ability of pancreatic cancer cells to adhesion and invasion, suggesting that MUC5AC might contribute to the invasive motility of pancreatic cancer cells by enhancing the expression of integrins, MMP-3, VEGF and activating Erk pathway.

The Adder Phenomenon Emerges from Independent Control of Pre- and Post-Start Phases of the Budding Yeast Cell Cycle.

Science.gov (United States)

Chandler-Brown, Devon; Schmoller, Kurt M; Winetraub, Yonatan; Skotheim, Jan M

2017-09-25

Although it has long been clear that cells actively regulate their size, the molecular mechanisms underlying this regulation have remained poorly understood. In budding yeast, cell size primarily modulates the duration of the cell-division cycle by controlling the G1/S transition known as Start. We have recently shown that the rate of progression through Start increases with cell size, because cell growth dilutes the cell-cycle inhibitor Whi5 in G1. Recent phenomenological studies in yeast and bacteria have shown that these cells add an approximately constant volume during each complete cell cycle, independent of their size at birth. These results seem to be in conflict, as the phenomenological studies suggest that cells measure the amount they grow, rather than their size, and that size control acts over the whole cell cycle, rather than specifically in G1. Here, we propose an integrated model that unifies the adder phenomenology with the molecular mechanism of G1/S cell-size control. We use single-cell microscopy to parameterize a full cell-cycle model based on independent control of pre- and post-Start cell-cycle periods. We find that our model predicts the size-independent amount of cell growth during the full cell cycle. This suggests that the adder phenomenon is an emergent property of the independent regulation of pre- and post-Start cell-cycle periods rather than the consequence of an underlying molecular mechanism measuring a fixed amount of growth. Copyright © 2017 Elsevier Ltd. All rights reserved.

Gamma-irradiation produces active chlorine species (ACS) in physiological solutions: Secoisolariciresinol diglucoside (SDG) scavenges ACS - A novel mechanism of DNA radioprotection.

Science.gov (United States)

Mishra, Om P; Popov, Anatoliy V; Pietrofesa, Ralph A; Christofidou-Solomidou, Melpo

2016-09-01

Secoisolariciresinol diglucoside (SDG), the main lignan in whole grain flaxseed, is a potent antioxidant and free radical scavenger with known radioprotective properties. However, the exact mechanism of SDG radioprotection is not well understood. The current study identified a novel mechanism of DNA radioprotection by SDG in physiological solutions by scavenging active chlorine species (ACS) and reducing chlorinated nucleobases. The ACS scavenging activity of SDG was determined using two highly specific fluoroprobes: hypochlorite-specific 3'-(p-aminophenyl) fluorescein (APF) and hydroxyl radical-sensitive 3'-(p-hydroxyphenyl) fluorescein (HPF). Dopamine, an SDG structural analog, was used for proton (1)H NMR studies to trap primary ACS radicals. Taurine N-chlorination was determined to demonstrate radiation-induced generation of hypochlorite, a secondary ACS. DNA protection was assessed by determining the extent of DNA fragmentation and plasmid DNA relaxation following exposure to ClO(-) and radiation. Purine base chlorination by ClO(-) and γ-radiation was determined by using 2-aminopurine (2-AP), a fluorescent analog of 6-aminopurine. Chloride anions (Cl(-)) consumed >90% of hydroxyl radicals in physiological solutions produced by γ-radiation resulting in ACS formation, which was detected by (1)H NMR. Importantly, SDG scavenged hypochlorite- and γ-radiation-induced ACS. In addition, SDG blunted ACS-induced fragmentation of calf thymus DNA and plasmid DNA relaxation. SDG treatment before or after ACS exposure decreased the ClO(-) or γ-radiation-induced chlorination of 2-AP. Exposure to γ-radiation resulted in increased taurine chlorination, indicative of ClO(-) generation. NMR studies revealed formation of primary ACS radicals (chlorine atoms (Cl) and dichloro radical anions (Cl2¯)), which were trapped by SDG and its structural analog dopamine. We demonstrate that γ-radiation induces the generation of ACS in physiological solutions. SDG treatment scavenged

Hopping models and ac universality

DEFF Research Database (Denmark)

Dyre, Jeppe; Schrøder, Thomas

2002-01-01

Some general relations for hopping models are established. We proceed to discuss the universality of the ac conductivity which arises in the extreme disorder limit of the random barrier model. It is shown that the relevant dimension entering into the diffusion cluster approximation (DCA) is the h......Some general relations for hopping models are established. We proceed to discuss the universality of the ac conductivity which arises in the extreme disorder limit of the random barrier model. It is shown that the relevant dimension entering into the diffusion cluster approximation (DCA......) is the harmonic (fracton) dimension of the diffusion cluster. The temperature scaling of the dimensionless frequency entering into the DCA is discussed. Finally, some open problems regarding ac universality are listed....

Influences of Cry1Ac broccoli on larval survival and oviposition of diamondback moth.

Science.gov (United States)

Yi, Dengxia; Cui, Shusong; Yang, Limei; Fang, Zhiyuan; Liu, Yumei; Zhuang, Mu; Zhang, Yangyong

2015-01-01

Larval survival and oviposition behavior of three genotypes of diamondback moth, Plutella xylostella L. (Lepidoptera: Plutellidae), (homozygous Cry1Ac-susceptibile, Cry1Ac-resistant, and their F1 hybrids), on transgenic Bacillus thuringiensis (Bt) broccoli expressing different levels of Cry1Ac protein were evaluated in laboratory. These Bt broccoli lines were designated as relative low, medium, and high, respectively, according to the Cry1Ac content. Untransformed brocccoli plants were used as control. Larval survival of diamondback moth on non-Bt leaves was not significantly different among the three genotypes. The Cry1Ac-resistant larvae could survive on the low level of Bt broccoli plants, while Cry1Ac-susceptible and F1 larvae could not survive on them. The three genotypes of P. xylostella larvae could not survive on medium and high levels of Bt broccoli. In oviposition choice tests, there was no significant difference in the number of eggs laid by the three P. xylostella genotypes among different Bt broccoli plants. The development of Cry1Ac-susceptible and Cry1Ac-resistant P. xylostella on intact Bt plants was also tested in greenhouse. All susceptible P. xylostella larvae died on all Bt plants, while resistant larvae could survive on broccoli, which expresses low Cry1Ac protein under greenhouse conditions. The results of the greenhouse trials were similar to that of laboratory tests. This study indicated that high dose of Bt toxins in broccoli cultivars or germplasm lines is required for effective resistance management. © The Author 2015. Published by Oxford University Press on behalf of the Entomological Society of America.

Transport AC losses in YBCO coated conductors

Energy Technology Data Exchange (ETDEWEB)

Majoros, M [Ohio State University, Columbus, OH 43210 (United States); Ye, L [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Velichko, A V [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Coombs, T A [IRC in Superconductivity, University of Cambridge, Madingley Road, Cambridge CB3 0HE (United Kingdom); Sumption, M D [Ohio State University, Columbus, OH 43210 (United States); Collings, E W [Ohio State University, Columbus, OH 43210 (United States)

2007-09-15

Transport AC loss measurements have been made on YBCO-coated conductors prepared on two different substrate templates-RABiTS (rolling-assisted biaxially textured substrate) and IBAD (ion-beam-assisted deposition). RABiTS samples show higher losses compared with the theoretical values obtained from the critical state model, with constant critical current density, at currents lower than the critical current. An origin of this extra AC loss was demonstrated experimentally by comparison of the AC loss of two samples with different I-V curves. Despite a difference in I-V curves and in the critical currents, their measured losses, as well as the normalized losses, were practically the same. However, the functional dependence of the losses was affected by the ferromagnetic substrate. An influence of the presence of a ferromagnetic substrate on transport AC losses in YBCO film was calculated numerically by the finite element method. The presence of a ferromagnetic substrate increases transport AC losses in YBCO films depending on its relative magnetic permeability. The two loss contributions-transport AC loss in YBCO films and ferromagnetic loss in the substrate-cannot be considered as mutually independent.

Resonance reduction for AC drives with small capacitance in the DC link

DEFF Research Database (Denmark)

Máthé, Lászlo; Török, Lajos; Wang, Dong

2016-01-01

Pulse Width Modulated AC drives equipped with small DC-link capacitor are becoming an attractive solution for electric drive applications with moderate requirements for shaft dynamic performance. However, when these drives are fed from a weak grid a resonance between the line side impedance...... and the DC-link capacitor appears. Due to this resonance, the THD and the partially weighted harmonic distortion of the line currents are increased, which may rise compatibility problems with the AC line harmonic standards. By using vector control the motor drive is transformed into a constant power load...

Robust backstepping control of an interlink converter in a hybrid AC/DC microgrid based on feedback linearisation method

Science.gov (United States)

Dehkordi, N. Mahdian; Sadati, N.; Hamzeh, M.

2017-09-01

This paper presents a robust dc-link voltage as well as a current control strategy for a bidirectional interlink converter (BIC) in a hybrid ac/dc microgrid. To enhance the dc-bus voltage control, conventional methods strive to measure and feedforward the load or source power in the dc-bus control scheme. However, the conventional feedforward-based approaches require remote measurement with communications. Moreover, conventional methods suffer from stability and performance issues, mainly due to the use of the small-signal-based control design method. To overcome these issues, in this paper, the power from DG units of the dc subgrid imposed on the BIC is considered an unmeasurable disturbance signal. In the proposed method, in contrast to existing methods, using the nonlinear model of BIC, a robust controller that does not need the remote measurement with communications effectively rejects the impact of the disturbance signal imposed on the BIC's dc-link voltage. To avoid communication links, the robust controller has a plug-and-play feature that makes it possible to add a DG/load to or remove it from the dc subgrid without distorting the hybrid microgrid stability. Finally, Monte Carlo simulations are conducted to confirm the effectiveness of the proposed control strategy in MATLAB/SimPowerSystems software environment.

Distributed cooperative control of AC microgrids

Science.gov (United States)

Bidram, Ali

In this dissertation, the comprehensive secondary control of electric power microgrids is of concern. Microgrid technical challenges are mainly realized through the hierarchical control structure, including primary, secondary, and tertiary control levels. Primary control level is locally implemented at each distributed generator (DG), while the secondary and tertiary control levels are conventionally implemented through a centralized control structure. The centralized structure requires a central controller which increases the reliability concerns by posing the single point of failure. In this dissertation, the distributed control structure using the distributed cooperative control of multi-agent systems is exploited to increase the secondary control reliability. The secondary control objectives are microgrid voltage and frequency, and distributed generators (DGs) active and reactive powers. Fully distributed control protocols are implemented through distributed communication networks. In the distributed control structure, each DG only requires its own information and the information of its neighbors on the communication network. The distributed structure obviates the requirements for a central controller and complex communication network which, in turn, improves the system reliability. Since the DG dynamics are nonlinear and non-identical, input-output feedback linearization is used to transform the nonlinear dynamics of DGs to linear dynamics. Proposed control frameworks cover the control of microgrids containing inverter-based DGs. Typical microgrid test systems are used to verify the effectiveness of the proposed control protocols.

Circle of Security–Parenting: A randomized controlled trial in Head Start

Science.gov (United States)

CASSIDY, JUDE; BRETT, BONNIE E.; GROSS, JACQUELYN T.; STERN, JESSICA A.; MARTIN, DAVID R.; MOHR, JONATHAN J.; WOODHOUSE, SUSAN S.

2017-01-01

Although evidence shows that attachment insecurity and disorganization increase risk for the development of psychopathology (Fearon, Bakermans-Kranenburg, van IJzendoorn, Lapsley, & Roisman, 2010; Groh, Roisman, van IJzendoorn, Bakermans-Kranenburg, & Fearon, 2012), implementation challenges have precluded dissemination of attachment interventions on the broad scale at which they are needed. The Circle of Security–Parenting Intervention (COS-P; Cooper, Hoffman, & Powell, 2009), designed with broad implementation in mind, addresses this gap by training community service providers to use a manualized, video-based program to help caregivers provide a secure base and a safe haven for their children. The present study is a randomized controlled trial of COS-P in a low-income sample of Head Start enrolled children and their mothers. Mothers (N = 141; 75 intervention, 66 waitlist control) completed a baseline assessment and returned with their children after the 10-week intervention for the outcome assessment, which included the Strange Situation. Intent to treat analyses revealed a main effect for maternal response to child distress, with mothers assigned to COS-P reporting fewer unsupportive (but not more supportive) responses to distress than control group mothers, and a main effect for one dimension of child executive functioning (inhibitory control but not cognitive flexibility when maternal age and marital status were controlled), with intervention group children showing greater control. There were, however, no main effects of intervention for child attachment or behavior problems. Exploratory follow-up analyses suggested intervention effects were moderated by maternal attachment style or depressive symptoms, with moderated intervention effects emerging for child attachment security and disorganization, but not avoidance; for inhibitory control but not cognitive flexibility; and for child internalizing but not externalizing behavior problems. This initial

Circle of Security-Parenting: A randomized controlled trial in Head Start.

Science.gov (United States)

Cassidy, Jude; Brett, Bonnie E; Gross, Jacquelyn T; Stern, Jessica A; Martin, David R; Mohr, Jonathan J; Woodhouse, Susan S

2017-05-01

Although evidence shows that attachment insecurity and disorganization increase risk for the development of psychopathology (Fearon, Bakermans-Kranenburg, van IJzendoorn, Lapsley, & Roisman, 2010; Groh, Roisman, van IJzendoorn, Bakermans-Kranenburg, & Fearon, 2012), implementation challenges have precluded dissemination of attachment interventions on the broad scale at which they are needed. The Circle of Security-Parenting Intervention (COS-P; Cooper, Hoffman, & Powell, 2009), designed with broad implementation in mind, addresses this gap by training community service providers to use a manualized, video-based program to help caregivers provide a secure base and a safe haven for their children. The present study is a randomized controlled trial of COS-P in a low-income sample of Head Start enrolled children and their mothers. Mothers (N = 141; 75 intervention, 66 waitlist control) completed a baseline assessment and returned with their children after the 10-week intervention for the outcome assessment, which included the Strange Situation. Intent to treat analyses revealed a main effect for maternal response to child distress, with mothers assigned to COS-P reporting fewer unsupportive (but not more supportive) responses to distress than control group mothers, and a main effect for one dimension of child executive functioning (inhibitory control but not cognitive flexibility when maternal age and marital status were controlled), with intervention group children showing greater control. There were, however, no main effects of intervention for child attachment or behavior problems. Exploratory follow-up analyses suggested intervention effects were moderated by maternal attachment style or depressive symptoms, with moderated intervention effects emerging for child attachment security and disorganization, but not avoidance; for inhibitory control but not cognitive flexibility; and for child internalizing but not externalizing behavior problems. This initial randomized

Phage-Mediated Immuno-PCR for Ultrasensitive Detection of Cry1Ac Protein Based on Nanobody.

Science.gov (United States)

Liu, Yuanyuan; Jiang, Dongjian; Lu, Xin; Wang, Wei; Xu, Yang; He, Qinghua

2016-10-11

The widespread use of Cry proteins in transgenic plants for insect control has raised concerns about the environment and food safety in the public. An effective detection method for introduced Cry proteins is of significance for environmental risk assessment and product quality control. This paper describes a novel phage mediated immuno-PCR (iPCR) for the ultrasensitive determination of Cry proteins based on nanobodies. Three nanobodies against Cry1Ac protein were obtained from a naı̈ve phage displayed nanobody library without animal immunization process and were applied to the iPCR assay for Cry1Ac. The phage-mediated iPCR for Cry1Ac based on nanobodies showed a dynamic range of 0.001-100 ng/mL and a limit detection of 0.1 pg/mL. Specific measurement of this established method was performed by testing cross-reativity of other Cry1Ac analogues, and the result showed negligible cross-reactivity with other test Cry proteins (Cry1Ab, Cry1F, Cry3B). Furthermore, the phage-mediated iPCR based on nanobody should be easily applicable to the detection of many other Cry proteins.

The Start2Bike program is effective in increasing health-enhancing physical activity: a controlled study.

Science.gov (United States)

Ooms, Linda; Veenhof, Cindy; de Bakker, Dinny H

2017-06-29

The sports club is seen as a new relevant setting to promote health-enhancing physical activity (HEPA) among inactive population groups. Little is known about the effectiveness of strategies and activities implemented in the sports club setting on increasing HEPA levels. This study investigated the effects of Start2Bike, a six-week training program for inactive adults and adult novice cyclers, on HEPA levels of participants in the Netherlands. To measure physical activity, the Short QUestionnaire to ASsess Health-enhancing physical activity was used (SQUASH). Start2Bike participants were measured at baseline, six weeks and six months. A matched control group was measured at baseline and six months. The main outcome measure was whether participants met the Dutch Norm for Health-enhancing Physical Activity (DNHPA: 30 min of moderate-intensity activity on five days a week); Fit-norm (20 min of vigorous-intensity activity on three days a week); and Combi-norm (meeting the DNHPA and/or Fit-norm). Other outcome measures included: total minutes of physical activity per week; and minutes of physical activity per week per domain and intensity category. Statistical analyses consisted of McNemar tests and paired t-tests (within-group changes); and multiple logistic and linear regression analyses (between-group changes). In the Start2Bike group, compliance with Dutch physical activity norms increased significantly, both after six weeks and six months. Control group members did not alter their physical activity behavior. Between-group analyses showed that participants in the Start2Bike group were more likely to meet the Fit-norm at the six-month measurement compared to the control group (odds ratio = 2.5; 95% confidence interval (CI) = 1.1-5.8, p = 0.03). This was due to the Start2Bike participants spending on average 193 min/week more in vigorous-intensity activities (b = 193; 95% CI = 94-293, p Bike positively influences HEPA levels of participants by increasing

Dicty_cDB: FC-AC21 [Dicty_cDB

Lifescience Database Archive (English)

Full Text Available FC (Link to library) FC-AC21 (Link to dictyBase) - - - Contig-U15104-1 FC-AC21E (Li...nk to Original site) - - - - - - FC-AC21E 527 Show FC-AC21 Library FC (Link to library) Clone ID FC-AC21 (Link to dict...yBase) Atlas ID - NBRP ID - dictyBase ID - Link to Contig Contig-U15104-1 Original site URL http://dict...ce KDSLDVIIFPEMVKLVGLTPNTMEKVLTYFQDNDTIDLSTFPMEIQVEQLSGKYIFICTH KQKDQRCGYCGPILVDQLRDQIKERSLEKEIQVFGTSHVGGHKY... Frames) Frame A: KDSLDVIIFPEMVKLVGLTPNTMEKVLTYFQDNDTIDLSTFPMEIQVEQLSGKYIFICTH KQ

Herbal Medicine AC591 Prevents Oxaliplatin-Induced Peripheral Neuropathy in Animal Model and Cancer Patients

Directory of Open Access Journals (Sweden)

Xiaolan Cheng

2017-06-01

Full Text Available Oxaliplatin is clinically compelling because of severe peripheral neuropathy. The side effect can result in dosage reductions or even cessation of chemotherapy, and no effective treatments are available. AC591 is a standardized extract of Huangqi Guizhi Wuwu decoction, an herbal formula recorded in “Synopsis of the Golden Chamber” for improving limb numbness and pain. In this study, we investigated whether AC591 could protect against oxaliplatin-induced peripheral neuropathy. To clarify it, a rat model of oxaliplatin-induced peripheral neuropathy was established, and neuroprotective effect of AC591 was studied. Our results showed that pretreatment with AC591 reduced oxaliplatin-induced cold hyperalgesia, mechanical allodynia as well as morphological damage of dorsal root ganglion. Microarray analysis indicated the neuroprotective action of AC591 depended on the modulation of multiple molecular targets and pathways involved in the downregulation of inflammation and immune response. Moreover, AC591 enhanced the antitumor activity of oxaliplatin to some extent in Balb/c mice bearing CT-26 carcinoma cells. The efficacy of AC591 is also investigated in 72 colorectal cancer patients. After four cycles of treatment, the percentage of grades 1–2 neurotoxicity in AC591-treated group (n = 36 was 25%, whereas in the control group the incidence was 55.55% (P < 0.01 (n = 36. No significant differences in the tumor response rate between the two groups were found. These evidences suggested that AC591 can prevent oxaliplatin-induced neuropathy without reducing its antitumor activity, and may be a promising adjuvant to alleviate sensory symptoms in clinical practice.

THERMIONIC AC GENERATION

Science.gov (United States)

is shown that the maximum ac efficiency is equal to approximately 70% of the corresponding dc value. An illustrative example, including a proposed design for a rather unconventional transformer, is appended. (Author)

Flexible treatment of gestational diabetes modulated on ultrasound evaluation of intrauterine growth: a controlled randomized clinical trial.

Science.gov (United States)

Bonomo, M; Cetin, I; Pisoni, M P; Faden, D; Mion, E; Taricco, E; Nobile de Santis, M; Radaelli, T; Motta, G; Costa, M; Solerte, L; Morabito, A

2004-06-01

In order to prevent abnormalities of fetal growth still characterizing pregnancies complicated by Gestational Diabetes (GDM), in the present study we evaluated a therapeutic strategy for GDM based on ultrasound (US) measurement of fetal insulin-sensitive tissues. All GDM women diagnosed before 28th week immediately started diet and self-monitoring of blood glucose; after 2 weeks they were randomized to conventional (C) or modified (M) management. In C the glycemic target (GT) was fixed at 90 fasting/120 post-prandial mg/dl; in M GT varied, according to US measurement of the Abdominal Circumference (AC) centile performed every 2 weeks: 80/100 if AC > or =75th, 100/140 if AC or =75th c. Mean metabolic data were similar in the 2 groups, but in M a tightly-optimized subgroup, resulting from the lowering of GT due to AC > or =75th, coexisted with a less-controlled one, whose higher GT was justified by ACgrowth, with clear advantages on global pregnancy outcome.

21 CFR 880.6320 - AC-powered medical examination light.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered medical examination light. 880.6320... Miscellaneous Devices § 880.6320 AC-powered medical examination light. (a) Identification. An AC-powered medical examination light is an AC-powered device intended for medical purposes that is used to illuminate body...

Ac-dc converter firing error detection

International Nuclear Information System (INIS)

Gould, O.L.

1996-01-01

Each of the twelve Booster Main Magnet Power Supply modules consist of two three-phase, full-wave rectifier bridges in series to provide a 560 VDC maximum output. The harmonic contents of the twelve-pulse ac-dc converter output are multiples of the 60 Hz ac power input, with a predominant 720 Hz signal greater than 14 dB in magnitude above the closest harmonic components at maximum output. The 720 Hz harmonic is typically greater than 20 dB below the 500 VDC output signal under normal operation. Extracting specific harmonics from the rectifier output signal of a 6, 12, or 24 pulse ac-dc converter allows the detection of SCR firing angle errors or complete misfires. A bandpass filter provides the input signal to a frequency-to-voltage converter. Comparing the output of the frequency-to-voltage converter to a reference voltage level provides an indication of the magnitude of the harmonics in the ac-dc converter output signal

The Implementation of Satellite Control System Software Using Object Oriented Design

Science.gov (United States)

Anderson, Mark O.; Reid, Mark; Drury, Derek; Hansell, William; Phillips, Tom

1998-01-01

NASA established the Small Explorer (SMEX) program in 1988 to provide frequent opportunities for highly focused and relatively inexpensive space science missions that can be launched into low earth orbit by small expendable vehicles. The development schedule for each SMEX spacecraft was three years from start to launch. The SMEX program has produced five satellites; Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX), Fast Auroral Snapshot Explorer (FAST), Submillimeter Wave Astronomy Satellite (SWAS), Transition Region and Coronal Explorer (TRACE) and Wide-Field Infrared Explorer (WIRE). SAMPEX and FAST are on-orbit, TRACE is scheduled to be launched in April of 1998, WIRE is scheduled to be launched in September of 1998, and SWAS is scheduled to be launched in January of 1999. In each of these missions, the Attitude Control System (ACS) software was written using a modular procedural design. Current program goals require complete spacecraft development within 18 months. This requirement has increased pressure to write reusable flight software. Object-Oriented Design (OOD) offers the constructs for developing an application that only needs modification for mission unique requirements. This paper describes the OOD that was used to develop the SMEX-Lite ACS software. The SMEX-Lite ACS is three-axis controlled, momentum stabilized, and is capable of performing sub-arc-minute pointing. The paper first describes the high level requirements which governed the architecture of the SMEX-Lite ACS software. Next, the context in which the software resides is explained. The paper describes the benefits of encapsulation, inheritance and polymorphism with respect to the implementation of an ACS software system. This paper will discuss the design of several software components that comprise the ACS software. Specifically, Object-Oriented designs are presented for sensor data processing, attitude control, attitude determination and failure detection. The paper addresses

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

Science.gov (United States)

Pasch, James Jay

2017-02-07

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.

A Simple and General Approach to Determination of Self and Mutual Inductances for AC machines

DEFF Research Database (Denmark)

Lu, Kaiyuan; Rasmussen, Peter Omand; Ritchie, Ewen

2011-01-01

Modelling of AC electrical machines plays an important role in electrical engineering education related to electrical machine design and control. One of the fundamental requirements in AC machine modelling is to derive the self and mutual inductances, which could be position dependant. Theories...... developed so far for inductance determination are often associated with complicated machine magnetic field analysis, which exhibits a difficulty for most students. This paper describes a simple and general approach to the determination of self and mutual inductances of different types of AC machines. A new...... determination are given for a 3-phase, salient-pole synchronous machine, and an induction machine....

Grid support of a wind farm with active stall wind turbines and AC grid connection

DEFF Research Database (Denmark)

Hansen, Anca Daniela; Sørensen, Poul Ejnar; Iov, F.

2006-01-01

grid connection. The designed control system has the task of enabling such a wind farm to provide the best grid support. It is based on two control levels: a supervisory control level, which controls the power production of the whole farm by sending out reference signals to each individual wind turbine......One of the main concerns in the grid integration of large wind farms is their ability to behave as active controllable components in the power system. This article presents the design of a new integrated power control system for a wind farm made up exclusively of active stall wind turbines with AC......, and a local control level, which ensures that the reference power signals at the wind turbine level are reached. The ability of active stall wind farms with AC grid connection to control the power production to the reference power ordered by the operators is assessed and discussed by means of simulations....

An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

OpenAIRE

Liwen Pan; Chengning Zhang

2016-01-01

This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs). The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for m...

Drivability Improvement Control for Vehicle Start-Up Applied to an Automated Manual Transmission

Directory of Open Access Journals (Sweden)

Danna Jiang

2017-01-01

Full Text Available Drivability is the key factor for the automated manual transmission. It includes fast response to the driver’s demand and the driving comfort. This paper deals with a control methodology applied to an automated manual transmission vehicle for drivability enhancement during vehicle start-up phase. Based on a piecewise model of powertrain, a multiple-model predictive controller (mMPC is designed with the engine speed, clutch disc speed, and wheel speed as the measurable input variables and the engine torque reference and clutch friction torque reference as the controller’s output variables. The model not only includes the clutch dynamic, the flexible shaft dynamic, but also includes the actuators’ delay character. Considering the driver’s intention, a slipping speed trajectory is generated based on the acceleration pedal dynamically. The designed control strategy is verified on a complete powertrain and longitudinal vehicle dynamic model with different driver’s torque demands.

ACS sampling system: design, implementation, and performance evaluation

Science.gov (United States)

Di Marcantonio, Paolo; Cirami, Roberto; Chiozzi, Gianluca

2004-09-01

By means of ACS (ALMA Common Software) framework we designed and implemented a sampling system which allows sampling of every Characteristic Component Property with a specific, user-defined, sustained frequency limited only by the hardware. Collected data are sent to various clients (one or more Java plotting widgets, a dedicated GUI or a COTS application) using the ACS/CORBA Notification Channel. The data transport is optimized: samples are cached locally and sent in packets with a lower and user-defined frequency to keep network load under control. Simultaneous sampling of the Properties of different Components is also possible. Together with the design and implementation issues we present the performance of the sampling system evaluated on two different platforms: on a VME based system using VxWorks RTOS (currently adopted by ALMA) and on a PC/104+ embedded platform using Red Hat 9 Linux operating system. The PC/104+ solution offers, as an alternative, a low cost PC compatible hardware environment with free and open operating system.

Start up testing for the secure automated fabrication line

International Nuclear Information System (INIS)

Gerber, E.W.; Benson, E.M.; Dahl, R.E.

1987-01-01

The secure automated fabrication (SAF) line is a remotely operated, liquid metal reactor fuel fabrication process being built by Westinghouse Hanford Company for the Department of Energy. All process and control equipment is installed and start up testing has been initiated. Start up testing is comprised of five phases, each incorporating higher degrees of equipment integration, automation, and remote control. Testing methodology for SAF line start up is described in this report

Jump starting shared medical appointments for diabetes with weight management: Rationale and design of a randomized controlled trial.

Science.gov (United States)

Crowley, Matthew J; Edelman, David; Voils, Corrine I; Maciejewski, Matthew L; Coffman, Cynthia J; Jeffreys, Amy S; Turner, Marsha J; Gaillard, Leslie A; Hinton, Teresa A; Strawbridge, Elizabeth; Zervakis, Jennifer; Barton, Anna Beth; Yancy, William S

2017-07-01

Rates of glycemic control remain suboptimal nationwide. Medication intensification for diabetes can have undesirable side effects (weight gain, hypoglycemia), which offset the benefits of glycemic control. A Shared Medical Appointment (SMA) intervention for diabetes that emphasizes weight management could improve glycemic outcomes and reduce weight while simultaneously lowering diabetes medication needs, resulting in less hypoglycemia and better quality of life. We describe the rationale and design for a study evaluating a novel SMA intervention for diabetes that primarily emphasizes low-carbohydrate diet-focused weight management. Jump Starting Shared Medical Appointments for Diabetes with Weight Management (Jump Start) is a randomized, controlled trial that is allocating overweight Veterans (body mass index≥27kg/m 2 ) with type 2 diabetes into two arms: 1) a traditional SMA group focusing on medication management and self-management counseling; or 2) an SMA group that combines low-carbohydrate diet-focused weight management (WM/SMA) with medication management. Hemoglobin A1c reduction at 48weeks is the primary outcome. Secondary outcomes include hypoglycemic events, diabetes medication use, weight, medication adherence, diabetes-related quality of life, and cost-effectiveness. We hypothesize that WM/SMA will be non-inferior to standard SMA for glycemic control, and will reduce hypoglycemia, diabetes medication use, and weight relative to standard SMA, while also improving quality of life and costs. Jump Start targets two common problems that are closely related but infrequently managed together: diabetes and obesity. By focusing on diet and weight loss as the primary means to control diabetes, this intervention may improve several meaningful patient-centered outcomes related to diabetes. Copyright © 2017. Published by Elsevier Inc.

Characterisation of AC1: a naturally decaffeinated coffee

Directory of Open Access Journals (Sweden)

Luciana Benjamim Benatti

2012-01-01

Full Text Available We compared the biochemical characteristics of the beans of a naturally decaffeinated Arabica coffee (AC1 discovered in 2004 with those of the widely grown Brazilian Arabica cultivar "Mundo Novo" (MN. Although we observed differences during fruit development, the contents of amino acids, organic acids, chlorogenic acids, soluble sugars and trigonelline were similar in the ripe fruits of AC1 and MN. AC1 beans accumulated theobromine, and caffeine was almost entirely absent. Tests on the supply of [2-14C] adenine and enzymatic analysis of theobromine synthase and caffeine synthase in the endosperm of AC1 confirmed that, as in the leaves, caffeine synthesis is blocked during the methylation of theobromine to caffeine. The quality of the final coffee beverage obtained from AC1 was similar to that of MN.

Bioinformatics and Astrophysics Cluster (BinAc)

Science.gov (United States)

Krüger, Jens; Lutz, Volker; Bartusch, Felix; Dilling, Werner; Gorska, Anna; Schäfer, Christoph; Walter, Thomas

2017-09-01

BinAC provides central high performance computing capacities for bioinformaticians and astrophysicists from the state of Baden-Württemberg. The bwForCluster BinAC is part of the implementation concept for scientific computing for the universities in Baden-Württemberg. Community specific support is offered through the bwHPC-C5 project.

Audit-based Compliance Control (AC2) for EHR Systems

NARCIS (Netherlands)

Dekker, M.A.C.; den Hartog, Jeremy; Etalle, Sandro

2007-01-01

Traditionally, medical data is stored and processed using paper-based files. Recently, medical facilities have started to store, access and exchange medical data in digital form. The drivers for this change are mainly demands for cost reduction, and higher quality of health care. The main concerns

Ac, La, and Ce radioimpurities in {sup 225}Ac produced in 40-200 MeV proton irradiations of thorium

Energy Technology Data Exchange (ETDEWEB)

Engle, Jonathan W.; Ballard, Beau D. [Los Alamos National Laboratory, NM (United States); Weidner, John W. [Air Force Institute of Technology, Wright Patterson Air Force Base, OH (United States); and others

2014-10-01

Accelerator production of {sup 225}Ac addresses the global supply deficiency currently inhibiting clinical trials from establishing {sup 225}Ac's therapeutic utility, provided that the accelerator product is of sufficient radionuclidic purity for patient use. Two proton activation experiments utilizing the stacked foil technique between 40 and 200 MeV were employed to study the likely co-formation of radionuclides expected to be especially challenging to separate from {sup 225}Ac. Foils were assayed by nondestructive γ-spectroscopy and by α-spectroscopy of chemically processed target material. Nuclear formation cross sections for the radionuclides {sup 226}Ac and {sup 227}Ac as well as lower lanthanide radioisotopes {sup 139}Ce, {sup 141}Ce, {sup 143}Ce, and {sup 140}La whose elemental ionic radii closely match that of actinium were measured and are reported. The predictions of the latest MCNP6 event generators are compared with measured data, as they permit estimation of the formation rates of other radionuclides whose decay emissions are not clearly discerned in the complex spectra collected from {sup 232}Th(p,x) fission product mixtures. (orig.)

Research & Implementation of AC - DC Converter with High Power Factor & High Efficiency

Directory of Open Access Journals (Sweden)

Hsiou-Hsian Nien

2014-05-01

Full Text Available In this paper, we design and develop a high power factor, high efficiency two-stage AC - DC power converter. This paper proposes a two-stage AC - DC power converter. The first stage is boost active power factor correction circuit. The latter stage is near constant frequency LLC resonant converter. In addition to traditional LLC high efficiency advantages, light-load conversion efficiency of this power converter can be improved. And it possesses high power factor and near constant frequency operating characteristics, can significantly reduce the electromagnetic interference. This paper first discusses the main structure and control manner of power factor correction circuit. And then by the LLC resonant converter equivalent model proceed to circuit analysis to determine the important parameters of the converter circuit elements. Then design a variable frequency resonant tank. The resonant frequency can change automatically on the basis of the load to reach near constant frequency operation and a purpose of high efficiency. Finally, actually design and produce an AC – DC power converter with output of 190W to verify the characteristics and feasibility of this converter. The experimental results show that in a very light load (9.5 W the efficiency is as high as 81%, the highest efficiency of 88% (90 W. Full load efficiency is 87%. At 19 W ~ 190 W power changes, the operating frequency change is only 0.4 kHz (AC 110 V and 0.3 kHz (AC 220 V.

Transition towards DC micro grids: From an AC to a hybrid AC and DC energy infrastructure

Directory of Open Access Journals (Sweden)

Evi Ploumpidou

2017-12-01

Full Text Available Our electricity is predominantly powered by alternating current (AC, ever since the War of Currents ended in the favor of Nicola Tesla at the end of the 19th century. However, lots of the appliances we use, such as electronics and lights with light-emitting diode (LED technology, work internally on direct current (DC and it is projected that the number of these appliances will increase in the near future. Another contributor to the increase in DC consumption is the ongoing electrification of mobility (Electric Vehicles (EVs. At the same time, photovoltaics (PV generate DC voltages, while the most common storage technologies also use DC. In order to integrate all these appliances and technologies to the existing AC grid, there is a need for converters which introduce power losses. By distributing DC power to DC devices instead of converting it to AC first, it is possible to avoid substantial energy losses that occur every time electricity is converted. This situation initiated the concept for the implementation of the DC-Flexhouse project. A prototype DC installation will be developed and tested in one of the buildings of the developing living lab area called the District of Tomorrow (De Wijk van Morgen which is located in Heerlen, the Netherlands. A neighborhood cooperative (Vrieheide cooperatie is also part of the consortium in order to address the aspect of social acceptance. Although DC seems to be a promising solution for a more sustainable energy system, the business case is still debatable due to both technology- and market-related challenges. The current energy infrastructure is predominantly based on AC, manufacturers produce devices based on AC standards and people are using many AC products across a long life span. This Smart Energy Buildings & Cities (SEB&C PDEng project is a contribution to the DC-Flexhouse project. The aim is to analyze the challenges in the transition to DC micro grids, assess the market potential of DC

A single-phase PWM controlled AC to DC converter based on control of unity displacement power factor

OpenAIRE

Funabiki, Shigeyuki

1990-01-01

A modified pulse-width modulation (PWM) technique that improves the displacement power factor and the input power factor of a single-phase AC to DC converter is discussed. The modified converter is shown to have a high input power factor and allows the of DC voltage from zero to more than the maximum value of the source voltage. The displacement power factor is unity, and the input power factor is almost unity in the wide range of current command

The Ethylene Biosynthesis Gene CitACS4 Regulates Monoecy/Andromonoecy in Watermelon (Citrullus lanatus).

Science.gov (United States)

Manzano, Susana; Aguado, Encarnación; Martínez, Cecilia; Megías, Zoraida; García, Alicia; Jamilena, Manuel

2016-01-01

Monoecious and andromonoecious cultivars of watermelon are characterised by the production of male and female flower or male and hermaphrodite flowers, respectively. The segregation analysis in the offspring of crosses between monoecious and andromonoecious lines has demonstrated that this trait is controlled by a single gene pair, being the monoecious allele M semi-dominant to the andromonoecious allele A. The two studied F1 hybrids (MA) had a predominantly monoecious phenotype since both produced not only female flowers, but also bisexual flowers with incomplete stamens, and hermaphrodite flowers with pollen. Given that in other cucurbit species andromonoecy is conferred by mutations in the ethylene biosynthesis genes CmACS7, CsACS2 and CpACS27A we have cloned and characterised CitACS4, the watermelon gene showing the highest similarity with the formers. CitACS4 encoded for a type ACS type III enzyme that is predominantly expressed in pistillate flowers of watermelon. In the andromonoecious line we have detected a missense mutation in a very conserved residue of CitACS4 (C364W) that cosegregates with the andromonoecious phenotype in two independent F2 populations, concomitantly with a reduction in ethylene production in the floral buds that will develop as hermaphrodite flowers. The gene does not however co-segregates with other sex expression traits regulated by ethylene in this species, including pistillate flowering transition and the number of pistillate flowers per plant. These data indicate that CitAC4 is likely to be involved in the biosynthesis of the ethylene required for stamen arrest during the development of female flowers. The C364W mutation would reduce the production of ethylene in pistillate floral buds, promoting the conversion of female into hermaphrodite flowers, and therefore of monoecy into andromonoecy.

An adaptive neuro fuzzy inference system controlled space cector pulse width modulation based HVDC light transmission system under AC fault conditions

Science.gov (United States)

Ajay Kumar, M.; Srikanth, N. V.

2014-03-01

In HVDC Light transmission systems, converter control is one of the major fields of present day research works. In this paper, fuzzy logic controller is utilized for controlling both the converters of the space vector pulse width modulation (SVPWM) based HVDC Light transmission systems. Due to its complexity in the rule base formation, an intelligent controller known as adaptive neuro fuzzy inference system (ANFIS) controller is also introduced in this paper. The proposed ANFIS controller changes the PI gains automatically for different operating conditions. A hybrid learning method which combines and exploits the best features of both the back propagation algorithm and least square estimation method is used to train the 5-layer ANFIS controller. The performance of the proposed ANFIS controller is compared and validated with the fuzzy logic controller and also with the fixed gain conventional PI controller. The simulations are carried out in the MATLAB/SIMULINK environment. The results reveal that the proposed ANFIS controller is reducing power fluctuations at both the converters. It also improves the dynamic performance of the test power system effectively when tested for various ac fault conditions.

Expression of hybrid fusion protein (Cry1Ac::ASAL) in transgenic rice plants imparts resistance against multiple insect pests.

Science.gov (United States)

Boddupally, Dayakar; Tamirisa, Srinath; Gundra, Sivakrishna Rao; Vudem, Dashavantha Reddy; Khareedu, Venkateswara Rao

2018-05-31

To evolve rice varieties resistant to different groups of insect pests a fusion gene, comprising DI and DII domains of Bt Cry1Ac and carbohydrate binding domain of garlic lectin (ASAL), was constructed. Transgenic rice lines were generated and evaluated to assess the efficacy of Cry1Ac::ASAL fusion protein against three major pests, viz., yellow stem borer (YSB), leaf folder (LF) and brown planthopper (BPH). Molecular analyses of transgenic plants revealed stable integration and expression of the fusion gene. In planta insect bioassays on transgenics disclosed enhanced levels of resistance compared to the control plants. High insect mortality of YSB, LF and BPH was observed on transgenics compared to that of control plants. Furthermore, honeydew assays revealed significant decreases in the feeding ability of BPH on transgenic plants as compared to the controls. Ligand blot analysis, using BPH insects fed on cry1Ac::asal transgenic rice plants, revealed a modified receptor protein-binding pattern owing to its ability to bind to additional receptors in insects. The overall results authenticate that Cry1Ac::ASAL protein is endowed with remarkable entomotoxic effects against major lepidopteran and hemipteran insects. As such, the fusion gene appears promising and can be introduced into various other crops to control multiple insect pests.

Effects of AC Electric Field on Small Laminar Nonpremixed Flames

KAUST Repository

Xiong, Yuan

2015-04-01

Electric field can be a viable method in controlling various combustion properties. Comparing to traditional actuators, an application of electric field requires very small power consumption. Especially, alternating current (AC) has received attention recently, since it could modulate flames appreciably even for the cases when direct current (DC) has minimal effects. In this study, the effect of AC electric fields on small coflow diffusion flames is focused with applications of various laser diagnostic techniques. Flow characteristics of baseline diffusion flames, which corresponds to stationary small coflow diffusion flames when electric field is not applied, were firstly investigated with a particular focus on the flow field in near-nozzle region with the buoyancy force exerted on fuels due to density differences among fuel, ambient air, and burnt gas. The result showed that the buoyancy force exerted on the fuel as well as on burnt gas significantly distorted the near-nozzle flow-fields. In the fuels with densities heavier than air, recirculation zones were formed very close to the nozzle exit. Nozzle heating effect influenced this near-nozzle flow-field particularly among lighter fuels. Numerical simulations were also conducted and the results showed that a fuel inlet boundary condition with a fully developed velocity profile for cases with long fuel tubes should be specified inside the fuel tube to obtain satisfactory agreement in both the flow and temperature fields with those from experiment. With sub-critical AC applied to the baseline flames, particle image velocimetry (PIV), light scattering, laser-induced incandescence (LII), and laser-induced fluores- cence (LIF) techniques were adopted to identify the flow field and the structures of OH, polycyclic aromatic hydrocarbons (PAHs), soot zone. Under certain AC condi- tions of applied voltage and frequency, the distribution of PAHs and the flow field near the nozzle exit were drastically altered from the

ACS and STEMI treatment: gender-related issues.

Science.gov (United States)

Chieffo, Alaide; Buchanan, Gill Louise; Mauri, Fina; Mehilli, Julinda; Vaquerizo, Beatriz; Moynagh, Anouska; Mehran, Roxana; Morice, Marie-Claude

2012-08-01

Cardiovascular disease is the leading cause of death amongst women, with acute coronary syndromes (ACS) representing a significant proportion. It has been reported that in women presenting with ACS there is underdiagnosis and consequent undertreatment leading to an increase in hospital and long-term mortality. Several factors have to be taken into account, including lack of awareness both at patient and at physician level. Women are generally not aware of the cardiovascular risk and symptoms, often atypical, and therefore wait longer to seek medical attention. In addition, physicians often underestimate the risk of ACS in women leading to a further delay in accurate diagnosis and timely appropriate treatment, including cardiac catheterisation and primary percutaneous coronary intervention, with consequent delayed revascularisation times. It has been acknowledged by the European Society of Cardiology that gender disparities do exist, with a Class I, Level of Evidence B recommendation that both genders should be treated in the same way when presenting with ACS. However, there is still a lack of awareness and the mission of Women in Innovation, in association with Stent for Life, is to change the perception of women with ACS and to achieve prompt diagnosis and treatment.

Use of an AC/DC/AC Electrochemical Technique to Assess the Durability of Protection Systems for Magnesium Alloys

Science.gov (United States)

Song, Sen; McCune, Robert C.; Shen, Weidian; Wang, Yar-Ming

One task under the U.S. Automotive Materials Partnership (USAMP) "Magnesium Front End Research and Development" (MFERD) Project has been the evaluation of methodologies for the assessment of protective capability for a variety of proposed protection schemes for this hypothesized multi-material, articulated structure. Techniques which consider the entire protection system, including both pretreatments and topcoats are of interest. In recent years, an adaptation of the classical electrochemical impedance spectroscopy (EIS) approach using an intermediate cathodic DC polarization step (viz. AC/DC/AC) has been employed to accelerate breakdown of coating protection, specifically at the polymer-pretreatment interface. This work reports outcomes of studies to employ the AC/DC/AC approach for comparison of protective coatings to various magnesium alloys considered for front end structures. In at least one instance, the protective coating system breakdown could be attributed to the poorer intrinsic corrosion resistance of the sheet material (AZ31) relative to die-cast AM60B.

International comparison of AC-DC current transfer standards

Science.gov (United States)

Heine, G.; Garcocz, M.; Waldmann, W.

2017-01-01

The measurements of the international comparison of ac-dc current transfer standards identified as EURAMET.EM-K12 started in June 2012 and were completed in December 2014. Twenty NMIs in the EURAMET region and one NMI in the AFRIMET region took part: BEV (Austria), CMI (Czech Republic), PTB (Germany), METAS (Switzerland), JV (Norway), UME (Turkey), GUM (Poland), IPQ (Portugal), CEM (Spain), INRIM (Italy), SP (Sweden), DANIAmet-MI-Trescal (Denmark), BIM (Bulgaria), MKEH (Hungary), SIQ (Slovenia), LNE (France), NSAI NML (Ireland), VSL (The Netherlands), NPL (United Kingdom), Metrosert (Estonia), NIS (Egypt). The comparison was proposed to link the National Metrology Institutes organised in EURAMET to the key comparison CCEM-K12. The ac-dc current transfer difference of each travelling standard had been measured at its nominal current 10 mA and 5 A at the following frequencies: 10 Hz, 55 Hz, 1 kHz, 10 kHz, 20 kHz, 50 kHz, 100 kHz. The test points were selected to link the results with the equivalent CCEM Key Comparison (CCEM-K12), through five NMIs participating in both EURAMET and CCEM key comparisons (PTB, JV, NPL, SP and BEV). The report shows the degree of equivalence in the EURAMET region and also the degree of equivalence with the corresponding CCEM reference value. Main text To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCEM, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

Should fee-for-service be for all guideline-advocated acute coronary syndrome (ACS) care? Observations from the Snapshot ACS study.

Science.gov (United States)

Briffa, Thomas G; Hammett, Christopher J; Cross, David B; Macisaac, Andrew I; Rankin, James M; Board, Neville; Carr, Bridie; Hyun, Karice K; French, John; Brieger, David B; Chew, Derek P

2015-09-01

The aim of the present study was to explore the association of health insurance status on the provision of guideline-advocated acute coronary syndrome (ACS) care in Australia. Consecutive hospitalisations of suspected ACS from 14 to 27 May 2012 enrolled in the Snapshot study of Australian and New Zealand patients were evaluated. Descriptive and logistic regression analysis was performed to evaluate the association of patient risk and insurance status with the receipt of care. In all, 3391 patients with suspected ACS from 247 hospitals (23 private) were enrolled in the present study. One-third of patients declared private insurance coverage; of these, 27.9% (304/1088) presented to private facilities. Compared with public patients, privately insured patients were more likely to undergo in-patient echocardiography and receive early angiography; furthermore, in those with a discharge diagnosis of ACS, there was a higher rate of revascularisation (P fee-for-service. In contrast, proportionately fewer privately insured ACS patients were discharged on selected guideline therapies and were referred to a secondary prevention program (P = 0.056), neither of which directly attracts a fee. Typically, as GRACE (the Global Registry of Acute Coronary Events) risk score rose, so did the level of ACS care; however, propensity-adjusted analyses showed lower in-hospital adverse events among the insured group (odds ratio 0.68; 95% confidence interval 0.52-0.88; P = 0.004). Fee-for-service reimbursement may explain differences in the provision of selected guideline-advocated components of ACS care between privately insured and public patients.

AC/RF Superconductivity

Energy Technology Data Exchange (ETDEWEB)

Ciovati, G [Jefferson Lab (United States)

2014-07-01

This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

AC/RF Superconductivity

Energy Technology Data Exchange (ETDEWEB)

Ciovati, Gianluigi [JLAB

2015-02-01

This contribution provides a brief introduction to AC/RF superconductivity, with an emphasis on application to accelerators. The topics covered include the surface impedance of normal conductors and superconductors, the residual resistance, the field dependence of the surface resistance, and the superheating field.

Brain Oscillatory and Hemodynamic Activity in a Bimanual Coordination Task Following Transcranial Alternating Current Stimulation (tACS: A Combined EEG-fNIRS Study

Directory of Open Access Journals (Sweden)

Alisa Berger

2018-04-01

Full Text Available Motor control is associated with synchronized oscillatory activity at alpha (8–12 Hz and beta (12–30 Hz frequencies in a cerebello-thalamo-cortical network. Previous studies demonstrated that transcranial alternating current stimulation (tACS is capable of entraining ongoing oscillatory activity while also modulating motor control. However, the modulatory effects of tACS on both motor control and its underlying electro- and neurophysiological mechanisms remain ambiguous. Thus, the purpose of this study was to contribute to gathering neurophysiological knowledge regarding tACS effects by investigating the after-effects of 10 Hz tACS and 20 Hz tACS at parietal brain areas on bimanual coordination and its concurrent oscillatory and hemodynamic activity. Twenty-four right-handed healthy volunteers (12 females aged between 18 and 30 (M = 22.35 ± 3.62 participated in the study and performed a coordination task requiring bimanual movements. Concurrent to bimanual motor training, participants received either 10 Hz tACS, 20 Hz tACS or a sham stimulation over the parietal cortex (at P3/P4 electrode positions for 20 min via small gel electrodes (3,14 cm2 Ag/AgCl, amperage = 1 mA. Before and three time-points after tACS (immediately, 30 min and 1 day, bimanual coordination performance was assessed. Oscillatory activities were measured by electroencephalography (EEG and hemodynamic changes were examined using functional near-infrared spectroscopy (fNIRS. Improvements of bimanual coordination performance were not differently between groups, thus, no tACS-specific effect on bimanual coordination performance emerged. However, physiological measures during the task revealed significant increases in parietal alpha activity immediately following 10 Hz tACS and 20 Hz tACS which were accompanied by significant decreases of Hboxy concentration in the right hemispheric motor cortex compared to the sham group. Based on the physiological responses, we conclude that

Brain Oscillatory and Hemodynamic Activity in a Bimanual Coordination Task Following Transcranial Alternating Current Stimulation (tACS): A Combined EEG-fNIRS Study.

Science.gov (United States)

Berger, Alisa; Pixa, Nils H; Steinberg, Fabian; Doppelmayr, Michael

2018-01-01

Motor control is associated with synchronized oscillatory activity at alpha (8-12 Hz) and beta (12-30 Hz) frequencies in a cerebello-thalamo-cortical network. Previous studies demonstrated that transcranial alternating current stimulation (tACS) is capable of entraining ongoing oscillatory activity while also modulating motor control. However, the modulatory effects of tACS on both motor control and its underlying electro- and neurophysiological mechanisms remain ambiguous. Thus, the purpose of this study was to contribute to gathering neurophysiological knowledge regarding tACS effects by investigating the after-effects of 10 Hz tACS and 20 Hz tACS at parietal brain areas on bimanual coordination and its concurrent oscillatory and hemodynamic activity. Twenty-four right-handed healthy volunteers (12 females) aged between 18 and 30 ( M = 22.35 ± 3.62) participated in the study and performed a coordination task requiring bimanual movements. Concurrent to bimanual motor training, participants received either 10 Hz tACS, 20 Hz tACS or a sham stimulation over the parietal cortex (at P3/P4 electrode positions) for 20 min via small gel electrodes (3,14 cm 2 Ag/AgCl, amperage = 1 mA). Before and three time-points after tACS (immediately, 30 min and 1 day), bimanual coordination performance was assessed. Oscillatory activities were measured by electroencephalography (EEG) and hemodynamic changes were examined using functional near-infrared spectroscopy (fNIRS). Improvements of bimanual coordination performance were not differently between groups, thus, no tACS-specific effect on bimanual coordination performance emerged. However, physiological measures during the task revealed significant increases in parietal alpha activity immediately following 10 Hz tACS and 20 Hz tACS which were accompanied by significant decreases of Hboxy concentration in the right hemispheric motor cortex compared to the sham group. Based on the physiological responses, we conclude that tACS

Japan: The institute for the economy of energy recommends a quick re-start of nuclear reactors

International Nuclear Information System (INIS)

Anon.

2014-01-01

The Japanese Institute for the Economy of the Energy (IEEJ) considers that the sooner the nuclear reactors will re-start, the better the Japanese economy and environment will be. The 48 Japanese reactors were stopped after the Fukushima accident and their restart is linked to the implementation of new measures for reinforcing safety. Until now only 2 reactors Sendai 1 and Sendai 2 have been allowed to re-start. The procedure for the safety assessment of the reactors is slower than expected. A study shows that only 7 reactors may be allowed to re-start before march 2015 and a total of 19 units may be operating in march 2016. In this scenario 2% of the electricity will come from nuclear energy in 2014 and 15% in 2015, natural gas imports will still be necessary for the production of electricity and their global cost is estimated to reach 56 billions euros while Japan's rate of energy independence will drop by 4.6%. (A.C.)

Safe-commutation principle for direct single-phase AC-AC converters for use in audio power amplification

Energy Technology Data Exchange (ETDEWEB)

Ljusev, P.; Andersen, Michael A.E.

2005-07-01

This paper presents an alternative safe commutation principle for a single phase bidirectional bridge, for use in the new generation of direct single-stage AC-AC audio power amplifiers. As compared with the bridge commutation with load current or source voltage sensing, in this approach it is not required to do any measurements, thus making it more reliable. Initial testing made on the prototype prove the feasibility of the approach. (au)

Ac irreversibility line of bismuth-based high temperature superconductors

International Nuclear Information System (INIS)

Mehdaoui, A.; Beille, J.; Berling, D.; Loegel, B.; Noudem, J.G.; Tournier, R.

1997-01-01

We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe ac <100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL close-quote s for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.copyright 1997 Materials Research Society

AC, DC or EC motor? What type of engine for what purpose?; AC-, DC- oder EC-Motor? Welche Motorausfuehrung fuer welchen Zweck

Energy Technology Data Exchange (ETDEWEB)

Zeiff, Andreas; Homburg, Dietrich

2009-01-15

Electronics is the key technology in control engineering, but even the best control system requires reliable modules to transmit signals. Modern electric motors have become indispensable here. There are nearly as many motor types as there are applications. Electromagnetic conversion of electric into mechanical power is directly related to motor design. There are AC and DC motors, one-speed motors and variable-speed motors. Rotary momentum and synchronisation can be optimized by selecting the appropriate motor type, as can dynamics and detent torque. Correct selection of the electric motor therefore is essential for an optimal drive concept. (orig.)

Autonomous Active Power Control for Islanded AC Microgrids with Photovoltaic Generation and Energy Storage System

DEFF Research Database (Denmark)

Wu, Dan; Tang, Fen; Dragicevic, Tomislav

2014-01-01

In an islanded AC microgrid with distributed energy storage system (ESS), photovoltaic (PV) generation and loads, a coordinated active power regulation is required to ensure efficient utilization of renewable energy, while keeping the ESS from overcharge and over discharge conditions. In this paper...

ACS-Hach Programs: Supporting Excellence in High School Chemistry Teaching

Science.gov (United States)

Taylor, Terri

2009-05-01

In January 2009, the ACS received a gift of approximately $33 million from the Hach Scientific Foundation, the largest gift in the society's 133-year history. The foundation's programs will be continued by the ACS and will complement pre-existing ACS resources that support high school chemistry teaching. Three activities serve as the pillars of the ACS-Hach programs—the High School Chemistry Grant Program, the Second Career Teacher Scholarship Program, and the Land Grant University Scholars Program. Collectively, the ACS-Hach programs support high school chemistry teaching and learning by responding to the needs of both in-service and pre-service secondary teachers. The goals of each of the ACS-Hach programs align well with the ACS Mission—to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and its people.

ac driving amplitude dependent systematic error in scanning Kelvin probe microscope measurements: Detection and correction

International Nuclear Information System (INIS)

Wu Yan; Shannon, Mark A.

2006-01-01

The dependence of the contact potential difference (CPD) reading on the ac driving amplitude in scanning Kelvin probe microscope (SKPM) hinders researchers from quantifying true material properties. We show theoretically and demonstrate experimentally that an ac driving amplitude dependence in the SKPM measurement can come from a systematic error, and it is common for all tip sample systems as long as there is a nonzero tracking error in the feedback control loop of the instrument. We further propose a methodology to detect and to correct the ac driving amplitude dependent systematic error in SKPM measurements. The true contact potential difference can be found by applying a linear regression to the measured CPD versus one over ac driving amplitude data. Two scenarios are studied: (a) when the surface being scanned by SKPM is not semiconducting and there is an ac driving amplitude dependent systematic error; (b) when a semiconductor surface is probed and asymmetric band bending occurs when the systematic error is present. Experiments are conducted using a commercial SKPM and CPD measurement results of two systems: platinum-iridium/gap/gold and platinum-iridium/gap/thermal oxide/silicon are discussed

Computer soundcard as an AC signal generator and oscilloscope for the physics laboratory

Science.gov (United States)

Sinlapanuntakul, Jinda; Kijamnajsuk, Puchong; Jetjamnong, Chanthawut; Chotikaprakhan, Sutharat

2018-01-01

The purpose of this paper is to develop both an AC signal generator and a dual-channel oscilloscope based on standard personal computer equipped with sound card as parts of the laboratory of the fundamental physics and the introduction to electronics classes. The setup turns the computer into the two channel measured device which can provides sample rate, simultaneous sampling, frequency range, filters and others essential capabilities required to perform amplitude, phase and frequency measurements of AC signal. The AC signal also generate from the same computer sound card output simultaneously in any waveform such as sine, square, triangle, saw-toothed pulsed, swept sine and white noise etc. These can convert an inexpensive PC sound card into powerful device, which allows the students to measure physical phenomena with their own PCs either at home or at university attendance. A graphic user interface software was developed for control and analysis, including facilities for data recording, signal processing and real time measurement display. The result is expanded utility of self-learning for the students in the field of electronics both AC and DC circuits, including the sound and vibration experiments.

Two very long chain fatty acid acyl-CoA synthetase genes, acs-20 and acs-22, have roles in the cuticle surface barrier in Caenorhabditis elegans.

Directory of Open Access Journals (Sweden)

Eriko Kage-Nakadai

Full Text Available In multicellular organisms, the surface barrier is essential for maintaining the internal environment. In mammals, the barrier is the stratum corneum. Fatty acid transport protein 4 (FATP4 is a key factor involved in forming the stratum corneum barrier. Mice lacking Fatp4 display early neonatal lethality with features such as tight, thick, and shiny skin, and a defective skin barrier. These symptoms are strikingly similar to those of a human skin disease called restrictive dermopathy. FATP4 is a member of the FATP family that possesses acyl-CoA synthetase activity for very long chain fatty acids. How Fatp4 contributes to skin barrier function, however, remains to be elucidated. In the present study, we characterized two Caenorhabditis elegans genes, acs-20 and acs-22, that are homologous to mammalian FATPs. Animals with mutant acs-20 exhibited defects in the cuticle barrier, which normally prevents the penetration of small molecules. acs-20 mutant animals also exhibited abnormalities in the cuticle structure, but not in epidermal cell fate or cell integrity. The acs-22 mutants rarely showed a barrier defect, whereas acs-20;acs-22 double mutants had severely disrupted barrier function. Moreover, the barrier defects of acs-20 and acs-20;acs-22 mutants were rescued by acs-20, acs-22, or human Fatp4 transgenes. We further demonstrated that the incorporation of exogenous very long chain fatty acids into sphingomyelin was reduced in acs-20 and acs-22 mutants. These findings indicate that C. elegans Fatp4 homologue(s have a crucial role in the surface barrier function and this model might be useful for studying the fundamental molecular mechanisms underlying human skin barrier and relevant diseases.

Improved insecticidal toxicity by fusing Cry1Ac of Bacillus thuringiensis with Av3 of Anemonia viridis.

Science.gov (United States)

Yan, Fu; Cheng, Xing; Ding, Xuezhi; Yao, Ting; Chen, Hanna; Li, Wenping; Hu, Shengbiao; Yu, Ziquan; Sun, Yunjun; Zhang, Youming; Xia, Liqiu

2014-05-01

Av3, a neurotoxin of Anemonia viridis, is toxic to crustaceans and cockroaches but inactive in mammals. In the present study, Av3 was expressed in Escherichia coli Origami B (DE3) and purified by reversed-phase liquid chromatography. The purified Av3 was injected into the hemocoel of Helicoverpa armigera, rendering the worm paralyzed. Then, Av3 was expressed alone or fusion expressed with the Cry1Ac in acrystalliferous strain Cry(-)B of Bacillus thuringiensis. The shape of Cry1Ac was changed by fusion with Av3. The expressed fusion protein, Cry1AcAv3, formed irregular rhombus- or crescent-shaped crystalline inclusions, which is quite different from the shape of original Cry1Ac crystals. The toxicity of Cry1Ac was improved by fused expression. Compared with original Cry1Ac expressed in Cry(-)B, the oral toxicity of Cry1AcAv3 to H. armigera was elevated about 2.6-fold. No toxicity was detected when Av3 was expressed in Cry(-)B alone. The present study confirmed that marine toxins could be used in bio-control and implied that fused expression with other insecticidal proteins could be an efficient way for their application.

Magnetic irreversibility in granular superconductors: ac susceptibility study

International Nuclear Information System (INIS)

Perez, F.; Obradors, X.; Fontcuberta, J.; Vallet, M.; Gonzalez-Calbet, J.

1991-01-01

Ac susceptibility measurements of a ceramic weak-coupled superconductor in very low ac fields (2mG, 111Hz) are reported. We present evidence for the observation of the magnetic irreversibility following a ZFC-FC thermal cycling by means of ac susceptibilty measurements. It is shown that this technique also reflect local magnetic field effects in granular superconductors, as previously suggested in microwave surface resistance and I-V characteristics. (orig.)

Inkjet printing of multifilamentary YBCO for low AC loss coated conductors

International Nuclear Information System (INIS)

Hopkins, S C; Joseph, D; Mitchell-Williams, T B; Glowacki, B A; Calleja, A; Vlad, V R; Vilardell, M; Ricart, S; Granados, X; Puig, T; Obradors, X; Usoskin, A; Falter, M; Bäcker, M

2014-01-01

Considerable progress has been made with the development of REBCO coated conductors in recent years, and high performance conductors are available commercially. For many applications, however, the cost remains prohibitive, and AC losses discourage their selection for higher frequency applications. Chemical solution deposition (CSD) methods are attractive for low-cost, scalable preparation of buffer and superconductor layers, and in many respects inkjet printing is the method of choice, permitting non-contact deposition with minimal materials wastage and excellent control of coating thickness. Highly textured coatings of YBCO and Gd-doped CeO 2 have previously been reported on buffered metal substrates. Inkjet printing also introduces the possibility of patterning - directly depositing two and three dimensional structures without subtractive processing - offering a low-cost route to coated conductors with reduced AC losses. In this contribution, the inkjet deposition of superconducting YBCO tracks is reported on industrially relevant buffered metal substrates both by direct printing and an inverse patterning approach. In the latter approach, ceria tracks were printed reported, which are a candidate both for resistive filament spacers and buffer layers. TFA-based precursor solutions have been printed on SS/ABAD-YSZ/CeO 2 and Ni-W/LZO/CeO 2 RABiTS substrates, and the resulting multifilamentary samples characterised by microscopy and scanning Hall probe measurements. The prospects for future inkjet-printed low AC loss coated conductors are discussed, including control of interfilamentary resistivity and bridging, transposed filamentary structures and stabilisation material.

Ac irreversibility line of bismuth-based high temperature superconductors

Energy Technology Data Exchange (ETDEWEB)

Mehdaoui, A. [Laboratoire de Physique et de Spectroscopie Electronique, URA 1435 Faculte des Sciences, Universite de Haute Alsace 4, rue des Freres Lumiere, 68093 Mulhouse Cedex (France); Beille, J. [Laboratoire Louis Neel, CNRS, BP 166, 38042 Grenoble Cedex 9 (France); Berling, D.; Loegel, B. [Laboratoire de Physique et de Spectroscopie Electronique, URA 1435 Faculte des Sciences, Universite de Haute Alsace 4, rue des Freres Lumiere, 68093 Mulhouse Cedex (France); Noudem, J.G.; Tournier, R. [EPM-MATFORMAG, Laboratoire dElaboration par Procede Magnetique, CNRS, BP 166, 38042 Grenoble Cedex 9 (France)

1997-09-01

We discuss the magnetic properties of lead doped Bi-2223 bulk samples obtained through combined magnetic melt texturing and hot pressing (MMTHP). The ac complex susceptibility measurements are achieved over a broad ac field range (1 Oe{lt}h{sub ac}{lt}100 Oe) and show highly anisotropic properties. The intergranular coupling is improved in the direction perpendicular to the applied stress and magnetic field direction, and an intragranular loss peak is observed for the first time. A comparison is made with other bismuth-based compounds and it is shown that the MMTHP process shifts the ac irreversibility line (ac IL) toward higher fields. It is also shown that all the ac IL{close_quote}s for quasi 2D bismuth-based compounds show a nearly quadratic temperature dependence and deviate therefore strongly from the linear behavior observed in quasi 3D compounds and expected from a critical state model.{copyright} {ital 1997 Materials Research Society.}

A Circulating-Current Suppression Method for Parallel-Connected Voltage-Source Inverters With Common DC and AC Buses

DEFF Research Database (Denmark)

Wei, Baoze; Guerrero, Josep M.; Quintero, Juan Carlos Vasquez

2017-01-01

This paper presents a theoretical study with experimental validation of a circulating-current suppression method for parallel operation of three-phase voltage source inverters (VSI), which may be suitable for modular parallel uninterruptible power supply systems or hybrid AC/DC microgrid applicat......This paper presents a theoretical study with experimental validation of a circulating-current suppression method for parallel operation of three-phase voltage source inverters (VSI), which may be suitable for modular parallel uninterruptible power supply systems or hybrid AC/DC microgrid......, and added into the conventional droop plus virtual impedance control. In the control architecture, the reference voltages of the inverters are generated by the primary control loop which consists of a droop control and a virtual impedance. The secondary control is used to compensate the voltage drop...

ECRH-assisted start-up in ITER

International Nuclear Information System (INIS)

Lloyd, B.; Carolan, P.G.; Warrick, C.D.

1996-07-01

In ITER, the electric field applied for ionisation and to ramp up the plasma current may be limited to ∼ 0.3 V/m. In this case, based on established theories of the avalanche process, it is shown that ohmic breakdown in ITER is only possible over a narrow range of pressure and magnetic error field. Therefore, ECRH may be necessary to provide robust and reliable start-up. ECRH can ensure prompt breakdown over a wide range of prefill pressure and error field and can also give control over the initial time and location of breakdown. For ECRH-assisted start-up in ITER, the power and pulse length requirements are essentially determined by the need to ensure burnthrough, i.e. complete ionisation of hydrogen and the transition to high ionisation states of impurities. A 0-D code (with inclusion of some 1-D effects) has been developed to analyse burnthrough in ITER. The 0-D simulations indicate that control of the deuterium density is the key factor for ensuring successful start-up in ITER, where the effects of neutral screening and dynamic fuelling by the ex-plasma volume are also crucial. It is concluded that without ECRH, successful start-up will only be possible over a very restricted range of parameters but 3MW of absorbed ECRH power will ensure reasonably robust start-up for a broad range of conditions with beryllium impurity. In the case of carbon impurity, even with an absorbed ECRH power of 5MW one may be restricted to low prefill pressure and/or low carbon concentration for successful start-up. (Author)

21 CFR 880.5100 - AC-powered adjustable hospital bed.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false AC-powered adjustable hospital bed. 880.5100 Section 880.5100 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES... Therapeutic Devices § 880.5100 AC-powered adjustable hospital bed. (a) Identification. An AC-powered...

Nonlinear AC susceptibility, surface and bulk shielding

Science.gov (United States)

van der Beek, C. J.; Indenbom, M. V.; D'Anna, G.; Benoit, W.

1996-02-01

We calculate the nonlinear AC response of a thin superconducting strip in perpendicular field, shielded by an edge current due to the geometrical barrier. A comparison with the results for infinite samples in parallel field, screened by a surface barrier, and with those for screening by a bulk current in the critical state, shows that the AC response due to a barrier has general features that are independent of geometry, and that are significantly different from those for screening by a bulk current in the critical state. By consequence, the nonlinear (global) AC susceptibility can be used to determine the origin of magnetic irreversibility. A comparison with experiments on a Bi 2Sr 2CaCu 2O 8+δ crystal shows that in this material, the low-frequency AC screening at high temperature is mainly due to the screening by an edge current, and that this is the unique source of the nonlinear magnetic response at temperatures above 40 K.

AC BREAKDOWN IN GASES

Science.gov (United States)

electron- emission (multipactor) region, and (3) the low-frequency region. The breakdown mechanism in each of these regions is explained. An extensive bibliography on AC breakdown in gases is included.

An Enhanced Power Sharing Scheme for Voltage unbalance and harmonics compensation in an islanded AC microgrid

DEFF Research Database (Denmark)

Han, Yang; Shen, Pan; Zhao, Xin

2016-01-01

In this paper, an enhanced hierarchical control structure with multiple current loop damping schemes for voltage unbalance and harmonics compensation in ac islanded microgrid is proposed to address unequal power sharing problems. The distributed generation (DG) is properly controlled to autonomou......In this paper, an enhanced hierarchical control structure with multiple current loop damping schemes for voltage unbalance and harmonics compensation in ac islanded microgrid is proposed to address unequal power sharing problems. The distributed generation (DG) is properly controlled...... to autonomously compensate voltage unbalance and harmonics while sharing the compensation effort for the real power, reactive power, unbalance and harmonic powers. The proposed control system of the microgrid mainly consists of the positive sequence real and reactive power droop controllers, voltage and current......) technique is adopted to send the compensation command of the secondary control and auxiliary control from the microgrid control center (MGCC) to the local controllers of DG unit. Finally, the hardware-in-the-loop (HIL) results using dSPACE 1006 platform are presented to demonstrate the effectiveness...

Start 2: Thinking one move ahead

Energy Technology Data Exchange (ETDEWEB)

Gaines, L.L.

1991-11-01

At their summit meeting in the spring of 1990, Presidents Bush and Gorbachev issued a joint statement expressing their intentions to continue the process of strategic arms control beyond the Strategic Arms Reduction Treaty (START), which was eventually signed in July 1991, toward agreement on further reductions. They set general goals for negotiation of a follow-on treaty to START, which has been called START II. President Bush`s historic speech on September 27, 1991, reinforced those goals and specified several actions the US would take. It is the purpose of this report to examine possible provisions of START II and the implications of those provisions for achievement of the goals set at the 1990 summit, for verifiability, and for US force planning. This look ahead will contribute to advance planning of appropriate negotiating positions, verification research and development (R&D), and force modernization and restructuring. This report describes the goals for a START II treaty and possible means for achieving them. It postulates one set of provisions for such a treaty, while it examines force structures for the US that could result from adoption of a treaty with these provisions. The adequacy of methods for verifying START II are examined and the implications of a START II treaty are postulated.

Start 2: Thinking one move ahead

Energy Technology Data Exchange (ETDEWEB)

Gaines, L.L.

1991-11-01

At their summit meeting in the spring of 1990, Presidents Bush and Gorbachev issued a joint statement expressing their intentions to continue the process of strategic arms control beyond the Strategic Arms Reduction Treaty (START), which was eventually signed in July 1991, toward agreement on further reductions. They set general goals for negotiation of a follow-on treaty to START, which has been called START II. President Bush's historic speech on September 27, 1991, reinforced those goals and specified several actions the US would take. It is the purpose of this report to examine possible provisions of START II and the implications of those provisions for achievement of the goals set at the 1990 summit, for verifiability, and for US force planning. This look ahead will contribute to advance planning of appropriate negotiating positions, verification research and development (R D), and force modernization and restructuring. This report describes the goals for a START II treaty and possible means for achieving them. It postulates one set of provisions for such a treaty, while it examines force structures for the US that could result from adoption of a treaty with these provisions. The adequacy of methods for verifying START II are examined and the implications of a START II treaty are postulated.

AC electric field induced dipole-based on-chip 3D cell rotation.

Science.gov (United States)

Benhal, Prateek; Chase, J Geoffrey; Gaynor, Paul; Oback, Björn; Wang, Wenhui

2014-08-07

The precise rotation of suspended cells is one of the many fundamental manipulations used in a wide range of biotechnological applications such as cell injection and enucleation in nuclear transfer (NT) cloning. Noticeably scarce among the existing rotation techniques is the three-dimensional (3D) rotation of cells on a single chip. Here we present an alternating current (ac) induced electric field-based biochip platform, which has an open-top sub-mm square chamber enclosed by four sidewall electrodes and two bottom electrodes, to achieve rotation about the two axes, thus 3D cell rotation. By applying an ac potential to the four sidewall electrodes, an in-plane (yaw) rotating electric field is generated and in-plane rotation is achieved. Similarly, by applying an ac potential to two opposite sidewall electrodes and the two bottom electrodes, an out-of-plane (pitch) rotating electric field is generated and rolling rotation is achieved. As a prompt proof-of-concept, bottom electrodes were constructed with transparent indium tin oxide (ITO) using the standard lift-off process and the sidewall electrodes were constructed using a low-cost micro-milling process and then assembled to form the chip. Through experiments, we demonstrate rotation of bovine oocytes of ~120 μm diameter about two axes, with the capability of controlling the rotation direction and the rate for each axis through control of the ac potential amplitude, frequency, and phase shift, and cell medium conductivity. The maximum observed rotation rate reached nearly 140° s⁻¹, while a consistent rotation rate reached up to 40° s⁻¹. Rotation rate spectra for zona pellucida-intact and zona pellucida-free oocytes were further compared and found to have no effective difference. This simple, transparent, cheap-to-manufacture, and open-top platform allows additional functional modules to be integrated to become a more powerful cell manipulation system.

Pengembangan Sistem Otomatisasi AC dan Lampu Menggunakan Fuzzy dan Raspberry Pi

Directory of Open Access Journals (Sweden)

Rudy Ariyanto

2017-11-01

Full Text Available Otomatisasi AC dan lampu dilakukan untuk menghemat energi yang digunakan pada kehidupan sehari-hari. Dalam pengembangan otomatisasi AC dan lampu perlu menerapkan sebuah perangkat yang memiliki fungsi maksimal dengan harga yang minimal. Raspberry Pi merupakan perangkat atau modul dengan harga rendah yang mampu melakukan komunikasi wireless tanpa bantuan modul lain. Dalam pengembangan otomatisasi AC dan lampu juga diperlukan sebuah metode yang mampu melakukan kontrol terhadap nyala AC dan lampu. Penerapan metode fuzzy dapat dilakukan untuk menghimpun informasi keadaan ruang yang didapat dari sensor untuk menentukan nyala AC dan lampu secara otomatis. Oleh sebab itu pada penelitian ini mengusulkan pengembangan otomatisasi AC dan lampu menggunakan Raspberry Pi dan Fuzzy. Otomatisasi AC dan lampu menggunakan Raspberry Pi yang menerapkan metode Fuzzy dapat menghemat energi hingga 59,87% dalam hal lama waktu nyala AC dan 57,47% untuk lumenasi lampu

Successful enrichment of the ubiquitous freshwater acI Actinobacteria.

Science.gov (United States)

Garcia, Sarahi L; McMahon, Katherine D; Grossart, Hans-Peter; Warnecke, Falk

2014-02-01

Actinobacteria of the acI lineage are often the numerically dominant bacterial phylum in surface freshwaters, where they can account for > 50% of total bacteria. Despite their abundance, there are no described isolates. In an effort to obtain enrichment of these ubiquitous freshwater Actinobacteria, diluted freshwater samples from Lake Grosse Fuchskuhle, Germany, were incubated in 96-well culture plates. With this method, a successful enrichment containing high abundances of a member of the lineage acI was established. Phylogenetic classification showed that the acI Actinobacteria of the enrichment belonged to the acI-B2 tribe, which seems to prefer acidic lakes. This enrichment grows to low cell densities and thus the oligotrophic nature of acI-B2 was confirmed. © 2013 Society for Applied Microbiology and John Wiley & Sons Ltd.

Enhancing the Capacity of the AC Distribution System Using DC Interlinks - A Step Towards Future DC Grid

DEFF Research Database (Denmark)

Chaudhary, Sanjay; Guerrero, Josep M.; Teodorescu, Remus

2015-01-01

The development of distributed generation system and electric vehicles is bound to strain the distribution network. A typical radial distribution feeder suffers from the voltage fluctuation and feeder overload in the presence of a large amount of variable renewable generation. This paper presents...... a concept of enhancing the power handling capacity of distribution networks using dc grid interconnections. Control of both the active and reactive power exchange between the ac feeder and the interconnecting power converter has been proposed for the voltage regulation at the ac feeder terminal. Besides......, the dc grid interconnection also allows the introduction of a common storage system which can be shared by the connected ac feeders, and the dc grid connection to other renewable energy resources. The increased power handling capacity and improved voltage profile of the ac distribution feeder using...

AcEST(EST sequences of Adiantum capillus-veneris and their annotation) - AcEST | LSDB Archive [Life Science Database Archive metadata

Lifescience Database Archive (English)

Full Text Available List Contact us AcEST AcEST(EST sequences of Adiantum capillus-veneris and their annotation) Data detail Dat...a name AcEST(EST sequences of Adiantum capillus-veneris and their annotation) DOI 10.18908/lsdba.nbdc00839-0...01 Description of data contents EST sequence of Adiantum capillus-veneris and its annotation (clone ID, libr...le search URL http://togodb.biosciencedbc.jp/togodb/view/archive_acest#en Data acquisition method Capillary ...ainst UniProtKB/Swiss-Prot and UniProtKB/TrEMBL databases) Number of data entries Adiantum capillus-veneris

Hybrid I-f starting and observer-based Ssnsorless control of single-phase BLDC-PM motor drives

DEFF Research Database (Denmark)

Iepure, Liviu Ioan; Boldea, Ion; Blaabjerg, Frede

2012-01-01

A motion sensorless control for single-phase permanent magnet brushless dc motor based on an I-f starting sequence and a real-time permanent magnet flux estimation is proposed here. The special calculation for extracting the position and speed used here implies the generating of an orthogonal flux...... system, the atan2 trigonometric function, and a phase-locked loop observer. The influence of the permanent magnet flux harmonic content is presented by analytical expressions and digital simulations. The proposed sensorless control is validated by complete experimental results on a commercial small high......-speed blower-motor (40 W, 10 krpm, 12 Vdc)....

Theoretical Simulation on the Assembly of Carbon Nanotubes Between Electrodes by AC Dielectrophoresis

Directory of Open Access Journals (Sweden)

Yang Liu

2008-01-01

Full Text Available Abstract The assembly of single-walled carbon nanotubes (SWCNTs using the AC dielectrophoresis technique is studied theoretically. It is found that the comb electrode bears better position control of SWCNTs compared to the parallel electrode. In the assembly, when some SWCNTs bridge the electrode first, they can greatly alter the local electrical field so as to “screen off” later coming SWCNTs, which contributes to the formation of dispersed SWCNT array. The screening distance scales with the gap width of electrodes and the length of SWCNTs, which provides a way to estimate the assembled density of SWCNTs. The influence of thermal noise on SWCNTs alignment is also analyzed in the simulation. It is shown that the status of the array distribution for SWCNTs is decided by the competition between the thermal noise and the AC electric-field strength. This influence of the thermal noise can be suppressed by using higher AC voltage to assemble the SWCNTs.

Design and synthesis of 225Ac radioimmunopharmaceuticals

International Nuclear Information System (INIS)

McDevitt, Michael R.; Ma, Dangshe; Simon, Jim; Frank, R. Keith; Scheinberg, David A.

2002-01-01

The alpha-particle-emitting radionuclides 213 Bi, 211 At, 224 Ra are under investigation for the treatment of leukemias, gliomas, and ankylosing spondylitis, respectively. 213 Bi and 211 At were attached to monoclonal antibodies and used as targeted immunotherapeutic agents while unconjugated 224 Ra chloride selectively seeks bone. 225 Ac possesses favorable physical properties for radioimmunotherapy (10 d half-life and 4 net alpha particles), but has a history of unfavorable radiolabeling chemistry and poor metal-chelate stability. We selected functionalized derivatives of DOTA as the most promising to pursue from out of a group of potential 225 Ac chelate compounds. A two-step synthetic process employing either MeO-DOTA-NCS or 2B-DOTA-NCS as the chelating moiety was developed to attach 225 Ac to monoclonal antibodies. This method was tested using several different IgG systems. The chelation reaction yield in the first step was 93±8% radiochemically pure (n=26). The second step yielded 225 Ac-DOTA-IgG constructs that were 95±5% radiochemically pure (n=27) and the mean percent immunoreactivity ranged from 25% to 81%, depending on the antibody used. This process has yielded several potential novel targeted 225 Ac-labeled immunotherapeutic agents that may now be evaluated in appropriate model systems and ultimately in humans

Nuclear structure of 231Ac

International Nuclear Information System (INIS)

Boutami, R.; Borge, M.J.G.; Mach, H.; Kurcewicz, W.; Fraile, L.M.; Gulda, K.; Aas, A.J.; Garcia-Raffi, L.M.; Lovhoiden, G.; Martinez, T.; Rubio, B.; Tain, J.L.; Tengblad, O.

2008-01-01

The low-energy structure of 231 Ac has been investigated by means of γ ray spectroscopy following the β - decay of 231 Ra. Multipolarities of 28 transitions have been established by measuring conversion electrons with a MINI-ORANGE electron spectrometer. The decay scheme of 231 Ra → 231 Ac has been constructed for the first time. The Advanced Time Delayed βγγ(t) method has been used to measure the half-lives of five levels. The moderately fast B(E1) transition rates derived suggest that the octupole effects, albeit weak, are still present in this exotic nucleus

MAPC transplantation confers a more durable benefit than AC133+ cell transplantation in severe hind limb ischemia.

Science.gov (United States)

Aranguren, Xabier L; Pelacho, Beatriz; Peñuelas, Ivan; Abizanda, Gloria; Uriz, Maialen; Ecay, Margarita; Collantaes, María; Araña, Miriam; Beerens, Manu; Coppiello, Giulia; Prieto, Inés; Perez-Ilzarbe, Maitane; Andreu, Enrique J; Luttun, Aernout; Prósper, Felipe

2011-01-01

There is a need for comparative studies to determine which cell types are better candidates to remedy ischemia. Here, we compared human AC133(+) cells and multipotent adult progenitor cells (hMAPC) in a mouse model reminiscent of critical limb ischemia. hMAPC or hAC133(+) cell transplantation induced a significant improvement in tissue perfusion (measured by microPET) 15 days posttransplantation compared to controls. This improvement persisted for 30 days in hMAPC-treated but not in hAC133(+)-injected animals. While transplantation of hAC133(+) cells promoted capillary growth, hMAPC transplantation also induced collateral expansion, decreased muscle necrosis/fibrosis, and improved muscle regeneration. Incorporation of differentiated hAC133(+) or hMAPC progeny into new vessels was limited; however, a paracrine angio/arteriogenic effect was demonstrated in animals treated with hMAPC. Accordingly, hMAPC-conditioned, but not hAC133(+)-conditioned, media stimulated vascular cell proliferation and prevented myoblast, endothelial, and smooth muscle cell apoptosis in vitro. Our study suggests that although hAC133(+) cell and hMAPC transplantation both contribute to vascular regeneration in ischemic limbs, hMAPC exert a more robust effect through trophic mechanisms, which translated into collateral and muscle fiber regeneration. This, in turn, conferred tissue protection and regeneration with longer term functional improvement. © 2011 Cognizant Comm. Corp.

Autographa californica multiple nucleopolyhedrovirus ac53 plays a role in nucleocapsid assembly

International Nuclear Information System (INIS)

Liu Chao; Li Zhaofei; Wu Wenbi; Li Lingling; Yuan Meijin; Pan Lijing; Yang Kai; Pang Yi

2008-01-01

Autographa californica multiple nucleopolyhedrovirus (AcMNPV) orf53 (ac53) is a highly conserved gene existing in all sequenced Lepidoptera and Hymenoptera baculoviruses, but its function remains unknown. To investigate its role in the baculovirus life cycle, an ac53 deletion virus (vAc ac53KO-PH-GFP ) was generated through homologous recombination in Escherichia coli. Fluorescence and light microscopy and titration analysis revealed that vAc ac53KO-PH-GFP could not produce infectious budded virus in infected Sf9 cells. Real-time PCR demonstrated that the ac53 deletion did not affect the levels of viral DNA replication. Electron microscopy showed that many lucent tubular shells devoid of the nucleoprotein core are present in the virogenic stroma and ring zone, indicating that the ac53 knockout affected nucleocapsid assembly. With a recombinant virus expressing an Ac53-GFP fusion protein, we observed that Ac53 was distributed within the cytoplasm and nucleus at 24 h post-infection, but afterwards accumulated predominantly near the nucleus-cytoplasm boundary. These data demonstrate that ac53 is involved in nucleocapsid assembly and is an essential gene for virus production

Marketingová komunikace AC Sparta Praha

OpenAIRE

Fanta, Jan

2016-01-01

Title: Marketing communications of AC Sparta Praha Objectives: The main objective of this thesis is to analyze contemporary state of marketing communications with the audience of AC Sparta Praha, identify deficiencies and develop a proposal to improve the marketing communications with fans of this club. Methods: In this thesis have been used methods of case study, analysis of available documents and texts, structured interview with director od marketing, and director of communications and pub...

Design of a DC-AC Link Converter for 500W Residential Wind Generator

Directory of Open Access Journals (Sweden)

Riza Muhida

2012-12-01

Full Text Available  As one of alternative sources of renewable energy, wind energy has an excellence prospect in Indonesia, particularly in coastal and hilly areas which have potential wind to generate electricity for residential uses. There is urgent need to locally develop low cost inverter of wind generator system for residential use. Recent developments in power electronic converters and embedded computing allow improvement of power electronic converter devices that enable integration of microcontrollers in its design. In this project, an inverter circuit with suitable control scheme design was developed. The circuit was to be used with a selected topology of Wind Energy Conversion System (WECS to convert electricity generated by a 500W direct-drive permanent magnet type wind generator which is typical for residential use. From single phase AC output of the generator, a rectifier circuit is designed to convert AC to DC voltage. Then a DC-DC boost converter is used to step up the voltage to a nominal DC voltage suitable for domestic use. The proposed inverter then will convert the DC voltage to sinusoidal AC. The duty cycle of sinusoidal Pulse-Width Modulated (SPWM signal controlling switches in the inverter was generated by a microcontroller. The lab-scale experimental rig involves simulation of wind generator by running a geared DC motor coupled with 500W wind generator where the prototype circuit was connected at the generator output. The experimental circuit produced single phase 240V sinusoidal AC voltage with frequency of 50Hz. Measured total harmonics distortion (THD of the voltage across load was 4.0% which is within the limit of 5% as recommended by IEEE Standard 519-1992.

Pipeline grounding condition: A control of pipe-to-soil potential for AC interference induced corrosion reduction

CSIR Research Space (South Africa)

Adedeji, KB

2017-02-01

Full Text Available The interference effect from high voltage overhead lines on nearby metallic pipelines is a major challenge for utility owners due to the induced AC potentials on metallic pipelines. Nevertheless, numerous mitigation techniques have been proposed...

Chapter 5: Modeling and Control of Three-Phase AC/DC Converter Including Phase-Locked Loop

DEFF Research Database (Denmark)

Zhou, Dao; Song, Yipeng; Blaabjerg, Frede

2018-01-01

In this chapter, a mathematical model of the power circuit of a three-phase AC/DC converter is developed in the stationary and synchronous reference frames. Then, the operation principle of the phasor locked loop is addressed to exact the angle information of the power grid to realize the accurat...

c-axis ac susceptibility in high-Tc superconductors

International Nuclear Information System (INIS)

Waldmann, O.; Lichtschlag, G.; Talalaevskii, A.; Kleiner, R.; Mueller, P.; Steinmeyer, F.; Gerhaeuser, W.

1996-01-01

We have investigated the angle and magnetic field dependence of the ac susceptibility in Bi 2 Sr 2 CaCu 2 O 8 and YBa 2 Cu 3 O 7 single crystals at low external fields. The ac field was applied perpendicular to the CuO 2 planes. The first and third harmonics of the ac susceptibility exhibit remarkably sharp features when the dc field component perpendicular to the CuO 2 planes passes a threshold field H th . H th is strongly temperature dependent, but is independent of the parallel field component. We propose a simple model which excellently explains the data. Within this model the peak structures are related to the irreversibility line. We discuss the implications of the model for the interpretation of the ac susceptibility. copyright 1996 The American Physical Society

Fast electric dipole transitions in Ra-Ac nuclei

International Nuclear Information System (INIS)

Ahmad, I.

1985-01-01

Lifetime of levels in 225 Ra, 225 Ac, and 227 Ac have been measured by delayed coincidence techniques and these have been used to determine the E1 gamma-ray transition probabilities. The reduced E1 transition probabilities. The reduced E1 transition probabilities in 225 Ra and 225 Ac are about two orders of magnitude larger than the values in mid-actinide nuclei. On the other hand, the E1 rate in 227 Ac is similar to those measured in heavier actinides. Previous studies suggest the presence of octupole deformation in all the three nuclei. The present investigation indicates that fast E1 transitions occur for nuclei with octupole deformation. However, the studies also show that there is no one-to-one correspondence between E1 rate and octupole deformation. 13 refs., 4 figs

Multi-Time Scale Model Order Reduction and Stability Consistency Certification of Inverter-Interfaced DG System in AC Microgrid

Directory of Open Access Journals (Sweden)

Xiaoxiao Meng

2018-01-01

Full Text Available AC microgrid mainly comprise inverter-interfaced distributed generators (IIDGs, which are nonlinear complex systems with multiple time scales, including frequency control, time delay measurements, and electromagnetic transients. The droop control-based IIDG in an AC microgrid is selected as the research object in this study, which comprises power droop controller, voltage- and current-loop controllers, and filter and line. The multi-time scale characteristics of the detailed IIDG model are divided based on singular perturbation theory. In addition, the IIDG model order is reduced by neglecting the system fast dynamics. The static and transient stability consistency of the IIDG model order reduction are demonstrated by extracting features of the IIDG small signal model and using the quadratic approximation method of the stability region boundary, respectively. The dynamic response consistencies of the IIDG model order reduction are evaluated using the frequency, damping and amplitude features extracted by the Prony transformation. Results are applicable to provide a simplified model for the dynamic characteristic analysis of IIDG systems in AC microgrid. The accuracy of the proposed method is verified by using the eigenvalue comparison, the transient stability index comparison and the dynamic time-domain simulation.

Characterization and snubbing of a bidirectional MCT in a resonant ac link converter

Science.gov (United States)

Lee, Tony; Elbuluk, Malik E.; Zinger, Donald S.

1993-01-01

The MOS-Controlled Thyristor (MCT) is emerging as a powerful switch that combines the better characteristics of existing power devices. A study of switching stresses on an MCT switch under zero voltage resonant switching is presented. The MCT is used as a bidirectional switch in an ac/ac pulse density modulated inverter for induction motor drive. Current and voltage spikes are observed and analyzed with variations in the timing of the switching. Different snubber circuit configurations are under investigation to minimize the effect of these transients. The results will be extended to study and test the MCT switching in a medium power (5 hp) induction motor drive.

Power Electronic Transformer based Three-Phase PWM AC Drives

Science.gov (United States)

Basu, Kaushik

A Transformer is used to provide galvanic isolation and to connect systems at different voltage levels. It is one of the largest and most expensive component in most of the high voltage and high power systems. Its size is inversely proportional to the operating frequency. The central idea behind a power electronic transformer (PET) also known as solid state transformer is to reduce the size of the transformer by increasing the frequency. Power electronic converters are used to change the frequency of operation. Steady reduction in the cost of the semiconductor switches and the advent of advanced magnetic materials with very low loss density and high saturation flux density implies economic viability and feasibility of a design with high power density. Application of PET is in generation of power from renewable energy sources, especially wind and solar. Other important application include grid tied inverters, UPS e.t.c. In this thesis non-resonant, single stage, bi-directional PET is considered. The main objective of this converter is to generate adjustable speed and magnitude pulse width modulated (PWM) ac waveforms from an ac or dc grid with a high frequency ac link. The windings of a high frequency transformer contains leakage inductance. Any switching transition of the power electronic converter connecting the inductive load and the transformer requires commutation of leakage energy. Commutation by passive means results in power loss, decrease in the frequency of operation, distortion in the output voltage waveform, reduction in reliability and power density. In this work a source based partially loss-less commutation of leakage energy has been proposed. This technique also results in partial soft-switching. A series of converters with novel PWM strategies have been proposed to minimize the frequency of leakage inductance commutation. These PETs achieve most of the important features of modern PWM ac drives including 1) Input power factor correction, 2) Common

Flexible AC transmission systems. Modelling and control

Energy Technology Data Exchange (ETDEWEB)

Zhang, Xiao-Ping [Birmingham Univ. (United Kingdom); Rehtanz, Christian [Technische Univ. Dortmund (Germany); Pal, Bikash [Imperial College, London (United Kingdom)

2012-11-01

This monograph presents advanced modelling, analysis and control techniques of FACTS. These topics reflect the recent research and development of FACTS controllers, and anticipate the future applications of FACTS in power systems. The book covers comprehensively a range of power-system control problems: from steady-state voltage and power flow control, to voltage and reactive power control, to voltage stability control, to small signal stability control using FACTS controllers. The book presents the modelling of the latest FACTS controllers for power flow control, compensation and power quality (IPFC, GUPF, VSC HVDC and M-VSCHVDC, etc.) in power system analysis. The selection is evaluated by the actual and likely future practical relevance of each. The material is derived mainly from the research and industrial development in which the authors have been heavily involved. The book is timely and of great value to power engineering engineers and students of modelling, simulations and control design of FACTS for a broad practical range of power system operation, planning and control problems.

Advanced DC/AC inverters applications in renewable energy

CERN Document Server

Luo, Fang Lin

2013-01-01

DC/AC inversion technology is of vital importance for industrial applications, including electrical vehicles and renewable energy systems, which require a large number of inverters. In recent years, inversion technology has developed rapidly, with new topologies improving the power factor and increasing power efficiency. Proposing many novel approaches, Advanced DC/AC Inverters: Applications in Renewable Energy describes advanced DC/AC inverters that can be used for renewable energy systems. The book introduces more than 100 topologies of advanced inverters originally developed by the authors,

Canadian biotechnology start-ups, 1991-1997: the role of incumbents' patents and strategic alliances in controlling competition.

Science.gov (United States)

Calabrese, T; Baum, J A; Silverman, B S

2000-12-01

Fligstein (1996) contends that organizations act to exploit the institutional context in which they are embedded so as to stabilize the competition they face. Drawing on Fligstein's theoretical analysis, we conceptualize incumbent biotechnology firms' patent-ing and alliance-building activities as attempts to stabilize and control potential competition and analyze how these activities shape rates of founding in the Canadian biotechnology industry. We find that increases in the level and concentration of incumbents' patenting discourage founding, particularly in human application sectors of the industry where development and approval processes are more costly and time consuming. Incumbents' horizontal alliances depress start-ups; vertical alliances stimulate start-ups. Our findings highlight how technology appropriation and strategic alliances structure the competitive dynamics and evolution of high-technology, knowledge-intensive industries.

Delayed Instructional Control of Head Start Children's Free Play.

Science.gov (United States)

Pierce, Charles H.; Risley, Todd R.

The free play of 5 black preschool Head Start children was observed. The variables manipulated in the study were delayed instructions and reinforcement for play with selected toys, and specific versus general instructions; the correspondence between the adult's instructions and reinforcement to the children's play was assessed. The data indicated…

Validation of self-reported start year of mobile phone use in a Swedish case-control study on radiofrequency fields and acoustic neuroma risk.

Science.gov (United States)

Pettersson, David; Bottai, Matteo; Mathiesen, Tiit; Prochazka, Michaela; Feychting, Maria

2015-01-01

The possible effect of radiofrequency exposure from mobile phones on tumor risk has been studied since the late 1990s. Yet, empirical information about recall of the start of mobile phone use among adult cases and controls has never been reported. Limited knowledge about recall errors hampers interpretations of the epidemiological evidence. We used network operator data to validate the self-reported start year of mobile phone use in a case-control study of mobile phone use and acoustic neuroma risk. The answers of 96 (29%) cases and 111 (22%) controls could be included in the validation. The larger proportion of cases reflects a more complete and detailed reporting of subscription history. Misclassification was substantial, with large random errors, small systematic errors, and no significant differences between cases and controls. The average difference between self-reported and operator start year was -0.62 (95% confidence interval: -1.42, 0.17) years for cases and -0.71 (-1.50, 0.07) years for controls, standard deviations were 3.92 and 4.17 years, respectively. Agreement between self-reported and operator-recorded data categorized into short, intermediate and long-term use was moderate (kappa statistic: 0.42). Should an association exist, dilution of risk estimates and distortion of exposure-response patterns for time since first mobile phone use could result from the large random errors in self-reported start year. Retrospective collection of operator data likely leads to a selection of "good reporters", with a higher proportion of cases. Thus, differential recall cannot be entirely excluded.

dc Arc Fault Effect on Hybrid ac/dc Microgrid

Science.gov (United States)

Fatima, Zahra

The advent of distributed energy resources (DER) and reliability and stability problems of the conventional grid system has given rise to the wide spread deployment of microgrids. Microgrids provide many advantages by incorporating renewable energy sources and increasing the reliability of the grid by isolating from the main grid in case of an outage. AC microgrids have been installed all over the world, but dc microgrids have been gaining interest due to the advantages they provide over ac microgrids. However the entire power network backbone is still ac and dc microgrids require expensive converters to connect to the ac power network. As a result hybrid ac/dc microgrids are gaining more attention as it combines the advantages of both ac and dc microgrids such as direct integration of ac and dc systems with minimum number of conversions which increases the efficiency by reducing energy losses. Although dc electric systems offer many advantages such as no synchronization and no reactive power, successful implementation of dc systems requires appropriate protection strategies. One unique protection challenge brought by the dc systems is dc arc faults. A dc arc fault is generated when there is a gap in the conductor due to insulation degradation and current is used to bridge the gap, resulting in an arc with very high temperature. Such a fault if it goes undetected and is not extinguished can cause damage to the entire system and cause fires. The purpose of the research is to study the effect of the dc arc fault at different locations in the hybrid ac/dc microgrid and provide insight on the reliability of the grid components when it is impacted by arc faults at various locations in the grid. The impact of dc arc fault at different locations on the performance of the PV array, wind generation, and constant power loads (CPL) interfaced with dc/dc converters is studied. MATLAB/Simulink is used to model the hybrid ac/dc microgrid and arc fault.

Frequency-dependent tACS modulation of BOLD signal during rhythmic visual stimulation.

Science.gov (United States)

Chai, Yuhui; Sheng, Jingwei; Bandettini, Peter A; Gao, Jia-Hong

2018-05-01

Transcranial alternating current stimulation (tACS) has emerged as a promising tool for modulating cortical oscillations. In previous electroencephalogram (EEG) studies, tACS has been found to modulate brain oscillatory activity in a frequency-specific manner. However, the spatial distribution and hemodynamic response for this modulation remains poorly understood. Functional magnetic resonance imaging (fMRI) has the advantage of measuring neuronal activity in regions not only below the tACS electrodes but also across the whole brain with high spatial resolution. Here, we measured fMRI signal while applying tACS to modulate rhythmic visual activity. During fMRI acquisition, tACS at different frequencies (4, 8, 16, and 32 Hz) was applied along with visual flicker stimulation at 8 and 16 Hz. We analyzed the blood-oxygen-level-dependent (BOLD) signal difference between tACS-ON vs tACS-OFF, and different frequency combinations (e.g., 4 Hz tACS, 8 Hz flicker vs 8 Hz tACS, 8 Hz flicker). We observed significant tACS modulation effects on BOLD responses when the tACS frequency matched the visual flicker frequency or the second harmonic frequency. The main effects were predominantly seen in regions that were activated by the visual task and targeted by the tACS current distribution. These findings bridge different scientific domains of tACS research and demonstrate that fMRI could localize the tACS effect on stimulus-induced brain rhythms, which could lead to a new approach for understanding the high-level cognitive process shaped by the ongoing oscillatory signal. © 2018 Wiley Periodicals, Inc.

Interleukin-13-induced MUC5AC is regulated by 15-lipoxygenase 1 pathway in human bronchial epithelial cells.

Science.gov (United States)

Zhao, Jinming; Maskrey, Ben; Balzar, Silvana; Chibana, Kazuyuki; Mustovich, Anthony; Hu, Haizhen; Trudeau, John B; O'Donnell, Valerie; Wenzel, Sally E

2009-05-01

15-Lipoxygenase-1 (15LO1) and MUC5AC are highly expressed in asthmatic epithelial cells. IL-13 is known to induce 15LO1 and MUC5AC in human airway epithelial cells in vitro. Whether 15LO1 and/or its product 15-HETE modulate MUC5AC expression is unknown. To determine the expression of 15LO1 in freshly harvested epithelial cells from subjects with asthma and normal control subjects and to determine whether IL-13-induced 15LO1 expression and activation regulate MUC5AC expression in human bronchial epithelial cells in vitro. Human airway epithelial cells from subjects with asthma and normal subjects were evaluated ex vivo for 15LO1 and MUC5AC expression. The impact of 15LO1 on MUC5AC expression in vitro was analyzed by inhibiting 15LO1 through pharmacologic (PD146176) and siRNA approaches in human bronchial epithelial cells cultured under air-liquid interface. We analyzed 15 hydroxyeicosatetraenoic acid (15-HETE) by liquid chromatography/UV/mass spectrometry. MUC5AC and 15LO1 were analyzed by real-time RT-PCR, immunofluoresence, and Western blot. Epithelial 15LO1 expression increased with asthma severity (P < 0.0001). 15LO1 significantly correlated with MUC5AC ex vivo and in vitro. IL-13 increased 15LO1 expression and stimulated formation of two molecular species of 15-HETE esterified to phosphotidylethanolamine (15-HETE-PE). Inhibition of 15LO1 suppressed 15-HETE-PE and decreased MUC5AC expression in the presence of IL-13 stimulation. The addition of exogenous 15-HETE partially restored MUC5AC expression. Epithelial 15LO1 expression increases with increasing asthma severity. IL-13 induction of 15-HETE-PE enhances MUC5AC expression in human airway epithelial cells. High levels of 15LO1 activity could contribute to the increases of MUC5AC observed in asthma.

Superconducting three element synchronous ac machine

International Nuclear Information System (INIS)

Boyer, L.; Chabrerie, J.P.; Mailfert, A.; Renard, M.

1975-01-01

There is a growing interest in ac superconducting machines. Of several new concepts proposed for these machines in the last years one of the most promising seems to be the ''three elements'' concept which allows the cancellation of the torque acting on the superconducting field winding, thus overcoming some of the major contraints. This concept leads to a device of induction-type generator. A synchronous, three element superconducting ac machine is described, in which a room temperature, dc fed rotating winding is inserted between the superconducting field winding and the ac armature. The steady-state machine theory is developed, the flux linkages are established, and the torque expressions are derived. The condition for zero torque on the field winding, as well as the resulting electrical equations of the machine, are given. The theoretical behavior of the machine is studied, using phasor diagrams and assuming for the superconducting field winding either a constant current or a constant flux condition

Efficient Lightweight AC-AC Power Control for Solar UAV, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — A highly efficient and lightweight dual bridge matrix power controller development is proposed that will provide high performance to a solar powered high altitude...

The influences of microwave irradiation and polyol precursor pH on Cu/AC catalyst and its CO oxidation performance

Science.gov (United States)

Chuang, Kui-Hao; Shih, Kaimin; Wey, Ming-Yen

2012-10-01

This study evaluated the effects of microwave irradiation parameters and the pH of the polyol precursor on the morphological features and catalytic performances of Cu/activated carbon (AC) catalysts. Experimental results of carbon monoxide (CO) oxidation indicated that the highest catalytic activity is achieved when the Cu/AC catalyst is prepared with microwave irradiation at 700 W for 60 s. Scanning electron microscopy revealed the presence of beneficial small copper aciculae on the Cu/AC catalyst under such a microwave irradiation scheme. Further investigation of operational parameters found that the performance of Cu/AC catalysts is enhanced by adopting a pH = 12 polyol precursor solution. With the observation that small cube copper ( 16 nm) aggregates form when a pH = 12 polyol precursor solution is used, this study also demonstrated the importance of controlling the morphology of metal nanoparticles on Cu/AC catalysts when using the microwave-assisted polyol method.

The influences of microwave irradiation and polyol precursor pH on Cu/AC catalyst and its CO oxidation performance

International Nuclear Information System (INIS)

Chuang, Kui-Hao; Shih, Kaimin; Wey, Ming-Yen

2012-01-01

This study evaluated the effects of microwave irradiation parameters and the pH of the polyol precursor on the morphological features and catalytic performances of Cu/activated carbon (AC) catalysts. Experimental results of carbon monoxide (CO) oxidation indicated that the highest catalytic activity is achieved when the Cu/AC catalyst is prepared with microwave irradiation at 700 W for 60 s. Scanning electron microscopy revealed the presence of beneficial small copper aciculae on the Cu/AC catalyst under such a microwave irradiation scheme. Further investigation of operational parameters found that the performance of Cu/AC catalysts is enhanced by adopting a pH = 12 polyol precursor solution. With the observation that small cube copper (∼16 nm) aggregates form when a pH = 12 polyol precursor solution is used, this study also demonstrated the importance of controlling the morphology of metal nanoparticles on Cu/AC catalysts when using the microwave-assisted polyol method.

Nontrivial ac spin response in the effective Luttinger model

International Nuclear Information System (INIS)

Hu Liangbin; Zhong Jiansong; Hu Kaige

2006-01-01

Based on the three-dimensional effective Luttinger Hamiltonian and the exact Heisenberg equations of motion and within a self-consistent semiclassical approximation, we present a theoretical investigation on the nontrivial ac spin responses due to the intrinsic spin-orbit coupling of holes in p-doped bulk semiconductors. We show that the nontrivial ac spin responses induced by the combined action of an ac external electric field and the intrinsic spin-orbit coupling of holes may lead to the generation of a nonvanishing ac spin Hall current in a p-doped bulk semiconductor, which shares some similarities with the dissipationless dc spin Hall current conceived previously and also exhibits some interesting new features that was not found before

Agronomic performance, chromosomal stability and resistance to velvetbean caterpillar of transgenic soybean expressing cry1Ac gene Performance agronômica, estabilidade cromossômica e resistência à lagarta-da-soja em soja transgênica que expressa o gene cry1Ac

Directory of Open Access Journals (Sweden)

Milena Schenkel Homrich

2008-07-01

Full Text Available The objective of this work was to analyze the agronomic performance and chromosomal stability of transgenic homozygous progenies of soybean [Glycine max (L. Merrill.], and to confirm the resistance of these plants against Anticarsia gemmatalis. Eleven progenies expressing cry1Ac, hpt and gusA genes were evaluated for agronomic characteristics in relation to the nontransformed parent IAS 5 cultivar. Cytogenetical analysis was carried out on transgenic and nontransgenic plants. Two out of the 11 transgenic progenies were also evaluated, in vitro and in vivo, for resistance to A. gemmatalis. Two negative controls were used in resistance bioassays: a transgenic homozygous line, containing only the gusA reporter gene, and nontransgenic 'IAS 5' plants. The presence of cry1Ac transgene affected neither the development nor the yield of plants. Cytogenetical analysis showed that transgenic plants presented normal karyotype. In detached-leaf bioassay, cry1Ac plants exhibited complete efficacy against A. gemmatalis, whereas negative controls were significantly damaged. Whole-plant feeding assay confirmed a very high protection of cry1Ac against velvetbean caterpillar, while nontransgenic 'IAS 5' plants and homozygous gusA line exhibited 56.5 and 71.5% defoliation, respectively. The presence of cry1Ac transgene doesn't affect the majority of agronomic traits (including yield of soybean and grants high protection against A. gemmatalis.O objetivo deste trabalho foi analisar a performance agronômica e a estabilidade cromossômica de progênies transgênicas homozigotas de soja [Glycine max (L. Merrill.], e confirmar a resistência dessas plantas a Anticarsia gemmatalis. Onze progênies com expressão dos genes cry1Ac, hpt e gusA foram avaliadas quanto às características agronômicas, em relação à cultivar parental IAS 5 não transformada. Análises citogenéticas foram realizadas em plantas transgênicas e não transgênicas. Duas das 11 prog

7 CFR 1737.31 - Area Coverage Survey (ACS).

Science.gov (United States)

2010-01-01

... an ACS are provided in RUS Telecommunications Engineering and Construction Manual section 205. (e... Studies-Area Coverage Survey and Loan Design § 1737.31 Area Coverage Survey (ACS). (a) The Area Coverage... the borrower's records contain sufficient information as to subscriber development to enable cost...

Disfonías espasmódicas: estudios acústicos

Directory of Open Access Journals (Sweden)

Liliana Sigal

2013-06-01

Full Text Available La disfonía espasmódica es un desorden vocal severo caracterizado por una interrupción involuntaria de la fonación, denominada también distonía focal laríngea. En este estudio se presentan los resultados de una investigación sobre las características acústico-vocales de una población de pacientes con disfonías espasmódicas, y la comparación de las mismas con las de un grupo control (sujetos con el diagnóstico otorrinolaringológico de cuerdas vocales móviles, sin daños estructurales en la mucosa glótica, ni alteraciones neurológicas que involucren la dinámica cordal. Se analizó acústicamente la vocal /a/ investigándose: valor de la frecuencia fundamental, desviación estándar, rango diferencial entre frecuencia máxima y mínima, y número de quiebres fonatorios. Se utilizó para estas mediciones el Sistema de análisis acústico Praat (Boersma y Weenink, 2003. En los resultados no se encontraron diferencias significativas entre las medias de la Frecuencia Fundamental entre ambos grupos estudiados.La comparación de los promedios del desvío estándar de la Frecuencia Fundamental arrojó sin embargo diferencias significativas, así como la comparación de los promedios de los rangos entre frecuenciamáxima y mínima. Respecto a la variable Quiebres Fonatorios, se calcularon solamente en el grupo de pacientes ya que ninguno de los sujetos del grupo control presentó interrupciones fonatorias en la emisión de la vocal. Cabe concluirse que la desviación estándar, el rango entre el valor máximo y mínimo de frecuencia fundamental y el número de interrupciones durante la emisión de vocal prolongada pueden utilizarse como indicadores de disfonía espasmódica.

An Integrated Multifunctional Bidirectional AC/DC and DC/DC Converter for Electric Vehicles Applications

Directory of Open Access Journals (Sweden)

Liwen Pan

2016-06-01

Full Text Available This paper presents an on-board vehicular battery charger that integrates bidirectional AC/DC converter and DC/DC converter to achieve high power density for application in electric vehicles (EVs. The integrated charger is able to transfer electrical energy between the battery pack and the electric traction system and to function as an AC/DC battery charger. The integrated charger topology is presented and the design of passive components is discussed. The control schemes are developed for motor drive system and battery-charging system with a power pulsation reduction circuit. Simulation results in MATLAB/Simulink and experiments on a 30-kW motor drive and 3.3-kW AC/DC charging prototype validate the performance of the proposed technology. In addition, power losses, efficiency comparison and thermal stress for the integrated charger are illustrated. The results of the analyses show the validity of the advanced integrated charger for electric vehicles.

AC dielectrophoresis alignment of single-walled carbon nano tubes (SWNTS) and palladium nano wires for hydrogen gas sensor

International Nuclear Information System (INIS)

Nur Ubaidah Saidin; Nur Ubaidah Saidin; Ying, K.K.; KKhuan, N.I.; Mohammad Hafizuddin Jumali

2013-01-01

Full-text: Using AC electric field, nano wires or nano tubes can be aligned, chained or accelerated in a direction parallel to the applied field, oriented or concentrated onto designated locations as well as dispersed in controlled manner under high efficiencies. In this work, systematic study on the alignment of nano wires/ nano tubes across the 3 μm-gaps between pairs of micro fabricated gold electrodes was carried out using AC dielectrophoresis technique. Densities and alignment of the nano wires/ nano tubes across the gaps of the electrodes were controlled by the applied AC field strengths and frequencies on the electrodes. Good alignments of SWNTs and Pd nano wires were achieved at an applied frequency of 5 MHz and a field strength as high as 25 V pp for Pd nano wires compared to only 2 V pp for SWNTs. The aligned nano wires/ nano tubes will be functioned as sensor elements for hydrogen gas sensing. (author)

Importance of Attenuation Correction (AC) for Small Animal PET Imaging

DEFF Research Database (Denmark)

El Ali, Henrik H.; Bodholdt, Rasmus Poul; Jørgensen, Jesper Tranekjær

2012-01-01

was performed. Methods: Ten NMRI nude mice with subcutaneous implantation of human breast cancer cells (MCF-7) were scanned consecutively in small animal PET and CT scanners (MicroPETTM Focus 120 and ImTek’s MicroCATTM II). CT-based AC, PET-based AC and uniform AC methods were compared. Results: The activity...

THE ACS NEARBY GALAXY SURVEY TREASURY

International Nuclear Information System (INIS)

Dalcanton, Julianne J.; Williams, Benjamin F.; Rosema, Keith; Gogarten, Stephanie M.; Christensen, Charlotte; Gilbert, Karoline; Hodge, Paul; Seth, Anil C.; Dolphin, Andrew; Holtzman, Jon; Skillman, Evan D.; Weisz, Daniel; Cole, Andrew; Girardi, Leo; Karachentsev, Igor D.; Olsen, Knut; Freeman, Ken; Gallart, Carme; Harris, Jason; De Jong, Roelof S.

2009-01-01

The ACS Nearby Galaxy Survey Treasury (ANGST) is a systematic survey to establish a legacy of uniform multi-color photometry of resolved stars for a volume-limited sample of nearby galaxies (D 4 in luminosity and star formation rate. The survey data consist of images taken with the Advanced Camera for Surveys (ACS) on the Hubble Space Telescope (HST), supplemented with archival data and new Wide Field Planetary Camera 2 (WFPC2) imaging taken after the failure of ACS. Survey images include wide field tilings covering the full radial extent of each galaxy, and single deep pointings in uncrowded regions of the most massive galaxies in the volume. The new wide field imaging in ANGST reaches median 50% completenesses of m F475W = 28.0 mag, m F606W = 27.3 mag, and m F814W = 27.3 mag, several magnitudes below the tip of the red giant branch (TRGB). The deep fields reach magnitudes sufficient to fully resolve the structure in the red clump. The resulting photometric catalogs are publicly accessible and contain over 34 million photometric measurements of >14 million stars. In this paper we present the details of the sample selection, imaging, data reduction, and the resulting photometric catalogs, along with an analysis of the photometric uncertainties (systematic and random), for both ACS and WFPC2 imaging. We also present uniformly derived relative distances measured from the apparent magnitude of the TRGB.

Experimental investigations on characteristics of boundary layer and control of transition on an airfoil by AC-DBD

Science.gov (United States)

Geng, Xi; Shi, Zhiwei; Cheng, Keming; Dong, Hao; Zhao, Qun; Chen, Sinuo

2018-03-01

Plasma-based flow control is one of the most promising techniques for aerodynamic problems, such as delaying the boundary layer transition. The boundary layer’s characteristics induced by AC-DBD plasma actuators and applied by the actuators to delay the boundary layer transition on airfoil at Ma = 0.3 were experimentally investigated. The PIV measurement was used to study the boundary layer’s characteristics induced by the plasma actuators. The measurement plane, which was parallel to the surface of the actuators and 1 mm above the surface, was involved in the test, including the perpendicular plane. The instantaneous results showed that the induced flow field consisted of many small size unsteady vortices which were eliminated by the time average. The subsequent oil-film interferometry skin friction measurement was conducted on a NASA SC(2)-0712 airfoil at Ma = 0.3. The coefficient of skin friction demonstrates that the plasma actuators successfully delay the boundary layer transition and the efficiency is better at higher driven voltage.

Scaling and universality of ac conduction in disordered solids

DEFF Research Database (Denmark)

Schrøder, Thomas; Dyre, Jeppe

2000-01-01

Recent scaling results for the ac conductivity of ionic glasses by Roling et al. [Phys. Rev. Lett. 78, 2160 (1997)] and Sidebottom [Phys. Rev. Lett. 82, 3653 (1999)] are discussed. We prove that Sidebottom's version of scaling is completely general. A new approximation to the universal ac conduct...... conductivity arising in the extreme disorder limit of the symmetric hopping model, the "diffusion cluster approximation," is presented and compared to computer simulations and experiments.......Recent scaling results for the ac conductivity of ionic glasses by Roling et al. [Phys. Rev. Lett. 78, 2160 (1997)] and Sidebottom [Phys. Rev. Lett. 82, 3653 (1999)] are discussed. We prove that Sidebottom's version of scaling is completely general. A new approximation to the universal ac...

VizieR Online Data Catalog: Hubble Legacy Archive ACS grism data (Kuemmel+, 2011)

Science.gov (United States)

Kuemmel, M.; Rosati, P.; Fosbury, R.; Haase, J.; Hook, R. N.; Kuntschner, H.; Lombardi, M.; Micol, A.; Nilsson, K. K.; Stoehr, F.; Walsh, J. R.

2011-09-01

A public release of slitless spectra, obtained with ACS/WFC and the G800L grism, is presented. Spectra were automatically extracted in a uniform way from 153 archival fields (or "associations") distributed across the two Galactic caps, covering all observations to 2008. The ACS G800L grism provides a wavelength range of 0.55-1.00um, with a dispersion of 40Å/pixel and a resolution of ~80Å for point-like sources. The ACS G800L images and matched direct images were reduced with an automatic pipeline that handles all steps from archive retrieval, alignment and astrometric calibration, direct image combination, catalogue generation, spectral extraction and collection of metadata. The large number of extracted spectra (73,581) demanded automatic methods for quality control and an automated classification algorithm was trained on the visual inspection of several thousand spectra. The final sample of quality controlled spectra includes 47919 datasets (65% of the total number of extracted spectra) for 32149 unique objects, with a median iAB-band magnitude of 23.7, reaching 26.5 AB for the faintest objects. Each released dataset contains science-ready 1D and 2D spectra, as well as multi-band image cutouts of corresponding sources and a useful preview page summarising the direct and slitless data, astrometric and photometric parameters. This release is part of the continuing effort to enhance the content of the Hubble Legacy Archive (HLA) with highly processed data products which significantly facilitate the scientific exploitation of the Hubble data. In order to characterize the slitless spectra, emission-line flux and equivalent width sensitivity of the ACS data were compared with public ground-based spectra in the GOODS-South field. An example list of emission line galaxies with two or more identified lines is also included, covering the redshift range 0.2-4.6. Almost all redshift determinations outside of the GOODS fields are new. The scope of science projects possible

Tomato leaf curl Kerala virus (ToLCKeV AC3 protein forms a higher order oligomer and enhances ATPase activity of replication initiator protein (Rep/AC1

Directory of Open Access Journals (Sweden)

Mukherjee Sunil K

2010-06-01

Full Text Available Abstract Background Geminiviruses are emerging plant viruses that infect a wide variety of vegetable crops, ornamental plants and cereal crops. They undergo recombination during co-infections by different species of geminiviruses and give rise to more virulent species. Antiviral strategies targeting a broad range of viruses necessitate a detailed understanding of the basic biology of the viruses. ToLCKeV, a virus prevalent in the tomato crop of Kerala state of India and a member of genus Begomovirus has been used as a model system in this study. Results AC3 is a geminiviral protein conserved across all the begomoviral species and is postulated to enhance viral DNA replication. In this work we have successfully expressed and purified the AC3 fusion proteins from E. coli. We demonstrated the higher order oligomerization of AC3 using sucrose gradient ultra-centrifugation and gel-filtration experiments. In addition we also established that ToLCKeV AC3 protein interacted with cognate AC1 protein and enhanced the AC1-mediated ATPase activity in vitro. Conclusions Highly hydrophobic viral protein AC3 can be purified as a fusion protein with either MBP or GST. The purification method of AC3 protein improves scope for the biochemical characterization of the viral protein. The enhancement of AC1-mediated ATPase activity might lead to increased viral DNA replication.

Analytical Modeling Approach to Study Harmonic Mitigation in AC Grids with Active Impedance at Selective Frequencies

Directory of Open Access Journals (Sweden)

Gonzalo Abad

2018-05-01

Full Text Available This paper presents an analytical model, oriented to study harmonic mitigation aspects in AC grids. As it is well known, the presence of non-desired harmonics in AC grids can be palliated in several manners. However, in this paper, a power electronic-based active impedance at selective frequencies (ACISEF is used, due to its already proven flexibility and adaptability to the changing characteristics of AC grids. Hence, the proposed analytical model approach is specially conceived to globally consider both the model of the AC grid itself with its electric equivalent impedances, together with the power electronic-based ACISEF, including its control loops. In addition, the proposed analytical model presents practical and useful properties, as it is simple to understand and simple to use, it has low computational cost and simple adaptability to different scenarios of AC grids, and it provides an accurate enough representation of the reality. The benefits of using the proposed analytical model are shown in this paper through some examples of its usefulness, including an analysis of stability and the identification of sources of instability for a robust design, an analysis of effectiveness in harmonic mitigation, an analysis to assist in the choice of the most suitable active impedance under a given state of the AC grid, an analysis of the interaction between different compensators, and so on. To conclude, experimental validation of a 2.15 kA ACISEF in a real 33 kV AC grid is provided, in which real users (household and industry loads and crucial elements such as wind parks and HVDC systems are near inter-connected.

Preliminary study on AC superconducting machines

International Nuclear Information System (INIS)

Yamamoto, M.; Ishigohka, T.; Shimohka, T.; Mizukami, N.; Yamaguchi, M.

1988-01-01

This paper describes the issues involved in developing AC superconducting machines. In the first phase, as a preliminary experiment, a 4kVa AC superconducting coil which employs 100A class 50/60Hz superconductors is made and tested. And, in the second phase, as an extension of the 4kVa coil, a model superconducting transformer is made and examined. The transformer has a novel quench protection system with an auxiliary coil only in the low voltage side. The behavior of the overcurrent protection system is confirmed

A toxin-binding alkaline phosphatase fragment synergizes Bt toxin Cry1Ac against susceptible and resistant Helicoverpa armigera.

Directory of Open Access Journals (Sweden)

Wenbo Chen

Full Text Available Evolution of resistance by insects threatens the continued success of pest control using insecticidal crystal (Cry proteins from the bacterium Bacillus thuringiensis (Bt in sprays and transgenic plants. In this study, laboratory selection with Cry1Ac yielded five strains of cotton bollworm, Helicoverpa armigera, with resistance ratios at the median lethal concentration (LC50 of activated Cry1Ac ranging from 22 to 1700. Reduced activity and reduced transcription of an alkaline phosphatase protein that binds Cry1Ac was associated with resistance to Cry1Ac in the four most resistant strains. A Cry1Ac-binding fragment of alkaline phosphatase from H. armigera (HaALP1f was not toxic by itself, but it increased mortality caused by Cry1Ac in a susceptible strain and in all five resistant strains. Although synergism of Bt toxins against susceptible insects by toxin-binding fragments of cadherin and aminopeptidase N has been reported previously, the results here provide the first evidence of synergism of a Bt toxin by a toxin-binding fragment of alkaline phosphatase. The results here also provide the first evidence of synergism of a Bt toxin by any toxin-binding peptide against resistant insects.

21 CFR 880.5500 - AC-powered patient lift.

Science.gov (United States)

2010-04-01

...) MEDICAL DEVICES GENERAL HOSPITAL AND PERSONAL USE DEVICES General Hospital and Personal Use Therapeutic Devices § 880.5500 AC-powered patient lift. (a) Identification. An AC-powered lift is an electrically powered device either fixed or mobile, used to lift and transport patients in the horizontal or other...

Error Assessment of Solar Irradiance Forecasts and AC Power from Energy Conversion Model in Grid-Connected Photovoltaic Systems

Directory of Open Access Journals (Sweden)

Gianfranco Chicco

2015-12-01

Full Text Available Availability of effective estimation of the power profiles of photovoltaic systems is essential for studying how to increase the share of intermittent renewable sources in the electricity mix of many countries. For this purpose, weather forecasts, together with historical data of the meteorological quantities, provide fundamental information. The weak point of the forecasts depends on variable sky conditions, when the clouds successively cover and uncover the solar disc. This causes remarkable positive and negative variations in the irradiance pattern measured at the photovoltaic (PV site location. This paper starts from 1 to 3 days-ahead solar irradiance forecasts available during one year, with a few points for each day. These forecasts are interpolated to obtain more irradiance estimations per day. The estimated irradiance data are used to classify the sky conditions into clear, variable or cloudy. The results are compared with the outcomes of the same classification carried out with the irradiance measured in meteorological stations at two real PV sites. The occurrence of irradiance spikes in “broken cloud” conditions is identified and discussed. From the measured irradiance, the Alternating Current (AC power injected into the grid at two PV sites is estimated by using a PV energy conversion model. The AC power errors resulting from the PV model with respect to on-site AC power measurements are shown and discussed.

Diagnostics of the Fermilab Tevatron using an AC dipole

Energy Technology Data Exchange (ETDEWEB)

Miyamoto, Ryoichi [Univ. of Texas, Austin, TX (United States)

2008-08-01

The Fermilab Tevatron is currently the world's highest energy colliding beam facility. Its counter-rotating proton and antiproton beams collide at 2 TeV center-of-mass. Delivery of such intense beam fluxes to experiments has required improved knowledge of the Tevatron's beam optical lattice. An oscillating dipole magnet, referred to as an AC dipole, is one of such a tool to non-destructively assess the optical properties of the synchrotron. We discusses development of an AC dipole system for the Tevatron, a fast-oscillating (f ~ 20 kHz) dipole magnet which can be adiabatically turned on and off to establish sustained coherent oscillations of the beam particles without affecting the transverse emittance. By utilizing an existing magnet and a higher power audio amplifier, the cost of the Tevatron AC dipole system became relatively inexpensive. We discuss corrections which must be applied to the driven oscillation measurements to obtain the proper interpretation of beam optical parameters from AC dipole studies. After successful operations of the Tevatron AC dipole system, AC dipole systems, similar to that in the Tevatron, will be build for the CERN LHC. We present several measurements of linear optical parameters (beta function and phase advance) for the Tevatron, as well as studies of non-linear perturbations from sextupole and octupole elements.

AC power flow importance measures considering multi-element failures

International Nuclear Information System (INIS)

Li, Jian; Dueñas-Osorio, Leonardo; Chen, Changkun; Shi, Congling

2017-01-01

Quantifying the criticality of individual components of power systems is essential for overall reliability and management. This paper proposes an AC-based power flow element importance measure, while considering multi-element failures. The measure relies on a proposed AC-based cascading failure model, which captures branch overflow, bus load shedding, and branch failures, via AC power flow and optimal power flow analyses. Taking the IEEE 30, 57 and 118-bus power systems as case studies, we find that N-3 analyses are sufficient to measure the importance of a bus or branch. It is observed that for a substation bus, its importance is statistically proportional to its power demand, but this trend is not observed for power plant buses. While comparing with other reliability, functionality, and topology-based importance measures popular today, we find that a DC power flow model, although better correlated with the benchmark AC model as a whole, still fails to locate some critical elements. This is due to the focus of DC-based models on real power that ignores reactive power. The proposed importance measure is aimed to inform decision makers about key components in complex systems, while improving cascading failure prevention, system backup setting, and overall resilience. - Highlights: • We propose a novel importance measure based on joint failures and AC power flow. • A cascading failure model considers both AC power flow and optimal power flow. • We find that N-3 analyses are sufficient to measure the importance of an element. • Power demand impacts the importance of substations but less so that of generators. • DC models fail to identify some key elements, despite correlating with AC models.

Preliminary Therapy Evaluation of 225Ac-DOTA-c(RGDyK) Demonstrates that Cerenkov Radiation Derived from 225Ac Daughter Decay Can Be Detected by Optical Imaging for In Vivo Tumor Visualization

Science.gov (United States)

Pandya, Darpan N.; Hantgan, Roy; Budzevich, Mikalai M.; Kock, Nancy D.; Morse, David L.; Batista, Izadora; Mintz, Akiva; Li, King C.; Wadas, Thaddeus J.

2016-01-01

The theranostic potential of 225Ac-based radiopharmaceuticals continues to increase as researchers seek innovative ways to harness the nuclear decay of this radioisotope for therapeutic and imaging applications. This communication describes the evaluation of 225Ac-DOTA-c(RGDyK) in both biodistribution and Cerenkov luminescence imaging (CLI) studies. Initially, La-DOTA-c(RGDyK) was prepared as a non-radioactive surrogate to evaluate methodologies that would contribute to an optimized radiochemical synthetic strategy and estimate the radioactive conjugate's affinity for αvβ3, using surface plasmon resonance spectroscopy. Surface plasmon resonance spectroscopy studies revealed the IC50 and Ki of La-DOTA-c(RGDyK) to be 33 ± 13 nM and 26 ± 11 nM, respectively, and suggest that the complexation of the La3+ ion to the conjugate did not significantly alter integrin binding. Furthermore, use of this surrogate allowed optimization of radiochemical synthesis strategies to prepare 225Ac-DOTA-c(RGDyK) with high radiochemical purity and specific activity similar to other 225Ac-based radiopharmaceuticals. This radiopharmaceutical was highly stable in vitro. In vivo biodistribution studies confirmed the radiotracer's ability to target αvβ3 integrin with specificity; specificity was detected in tumor-bearing animals using Cerenkov luminescence imaging. Furthermore, tumor growth control was achieved using non-toxic doses of the radiopharmaceutical in U87mg tumor-bearing nude mice. To our knowledge, this is the first report to describe the CLI of αvβ3+ tumors in live animals using the daughter products derived from 225Ac decay in situ. This concept holds promise to further enhance development of targeted alpha particle therapy. PMID:27022417

Systémový pohled na klub AC Sparta

OpenAIRE

Čečák, František

2015-01-01

Title: The system approach of the club AC Sparta Praha Objectives: Elaboration of financial analysis of the club AC Sparta Praha in season 2010/2011.Comparing the results of the financial analysis with the results of clubs FC Viktoria Plzeň and SK Slavia Praha. Prognosis of the club AC Sparta Praha until year 2020. Methods: In the elaboration of the analysis have been used these methods: vertical analysis, horizontal analysis and analysis of the financial ratios. For forecasting have been use...

Sordera por traumatismo acústico y accidentes auditivos en la Industria

Directory of Open Access Journals (Sweden)

Jorge García Gómez

1979-10-01

Full Text Available

SUMARIO Y CONCLUSIONES

1. La sordera ocupacional debe ser motivo de preocupación en medicina industrial, por cuanto constituye grave problema para los obreros que trabajan en ambiente de intensidades superiores a 90 decibeles. Consideramos de capital importancia iniciar urgente campaña para el estudio preventivo y profilaxis del ruido.

2. Los efectos que produce el ruído sobre la audición están ampliamente demostrados y, de acuerdo con la experiencia, su incidencia es cada día más frecuente en nuestro medio,
donde un alto porcentaje del personal obrero trabaja en ambientes sin ninguna protección y con grave peligro para su función auditiva.

3. La sordera ocupacional presenta características muy definidas, pero sólo un estudio otológico completo y la colaboración entre el otólogo, el ingeniero técnico en acústica y el
médico industrial permiten definir la conducta por seguir, su profilaxis y su tratamiento.

4. Las alteraciones orgánicas producidas en el oído por el trauma acústico son permanentes e irreversibles. Las estructuras del órgano de Corti una vez lesionadas no pueden ser
reemplazadas.

5. Sugerimos la creación del Comité Nacional de Conservación de la Audición con un programa que incluya:
a Formación de personal especializado.
b Estudio, reducción y control del ruído en la industria.
c Creación de la ficha audiológica obligatoria de ingreso para el personal obrero.
d Control periódico, protección del personal y adaptación de protectores acústicos.
el Establecimiento de normas mínimas acústicas en la construcción de las fábricas.

6. Las tablas de indemnización laboral por sordera deben ser modificadas, adoptando un sistema práctico, conforme con la legislación establecidaen otros países.

Interleukin-13–induced MUC5AC Is Regulated by 15-Lipoxygenase 1 Pathway in Human Bronchial Epithelial Cells

Science.gov (United States)

Zhao, Jinming; Maskrey, Ben; Balzar, Silvana; Chibana, Kazuyuki; Mustovich, Anthony; Hu, Haizhen; Trudeau, John B.; O'Donnell, Valerie; Wenzel, Sally E.

2009-01-01

Rationale: 15-Lipoxygenase-1 (15LO1) and MUC5AC are highly expressed in asthmatic epithelial cells. IL-13 is known to induce 15LO1 and MUC5AC in human airway epithelial cells in vitro. Whether 15LO1 and/or its product 15-HETE modulate MUC5AC expression is unknown. Objectives: To determine the expression of 15LO1 in freshly harvested epithelial cells from subjects with asthma and normal control subjects and to determine whether IL-13–induced 15LO1 expression and activation regulate MUC5AC expression in human bronchial epithelial cells in vitro. Methods: Human airway epithelial cells from subjects with asthma and normal subjects were evaluated ex vivo for 15LO1 and MUC5AC expression. The impact of 15LO1 on MUC5AC expression in vitro was analyzed by inhibiting 15LO1 through pharmacologic (PD146176) and siRNA approaches in human bronchial epithelial cells cultured under air–liquid interface. We analyzed 15 hydroxyeicosatetraenoic acid (15-HETE) by liquid chromatography/UV/mass spectrometry. MUC5AC and 15LO1 were analyzed by real-time RT-PCR, immunofluoresence, and Western blot. Measurements and Main Results: Epithelial 15LO1 expression increased with asthma severity (P < 0.0001). 15LO1 significantly correlated with MUC5AC ex vivo and in vitro. IL-13 increased 15LO1 expression and stimulated formation of two molecular species of 15-HETE esterified to phosphotidylethanolamine (15-HETE-PE). Inhibition of 15LO1 suppressed 15-HETE-PE and decreased MUC5AC expression in the presence of IL-13 stimulation. The addition of exogenous 15-HETE partially restored MUC5AC expression. Conclusions: Epithelial 15LO1 expression increases with increasing asthma severity. IL-13 induction of 15-HETE-PE enhances MUC5AC expression in human airway epithelial cells. High levels of 15LO1 activity could contribute to the increases of MUC5AC observed in asthma. PMID:19218191

Ac system interruption analysis of an orthogonal-core type dc-ac converter. Koryu keito shadanji no chokko jishinkei dc-ac renkeiyo henkanki no dosa kaiseki

Energy Technology Data Exchange (ETDEWEB)

Sato, K; Ichinokura, O; Jinzenji, T [Tohoku Univ., Sendai (Japan). Faculty of Engineering; Tajima, K [Akita University, Akita (Japan). Mining College

1991-04-30

This paper reports on a numerical analysis of transient response of an orthogonal-core type dc-ac converter that takes place when the external ac system connected is cut off from it. A model of magnetic circuit of the orthogonal core is presented, which has magnetic inductances to represent effects produced by hysteresis that are connected in series with magnetic reluctances, thereby making it possible to divide each of primary and secondary winding current into magnetization current associated with magnetic reluctances and iron-loss current due to hysteresis. Moreover, a numerical model of the orthogonal core is derived from expressions for non-linear characteristics of these reluctances and inductances to make use of it for analyses employing the circuit simulator SPICE. Transient response of the present converter, namely time variation of both voltage and current in its every part, to the sudden change in condition that is caused by switching off the ac system connected to its secondary side is calculated, while applying square-wave voltage to its primary side. It is noted that calculated wave forms of both secondary winding current and open-circuit voltage are fairly in good agreement with those obtained by an experiment performed on the same condition. 4 refs., 9 figs., 1 tab.

Design and synthesis of {sup 225}Ac radioimmunopharmaceuticals

Energy Technology Data Exchange (ETDEWEB)

McDevitt, Michael R.; Ma, Dangshe; Simon, Jim; Frank, R. Keith; Scheinberg, David A. E-mail: d-scheinberg@ski.mskcc.org

2002-12-01

The alpha-particle-emitting radionuclides {sup 213}Bi, {sup 211}At, {sup 224}Ra are under investigation for the treatment of leukemias, gliomas, and ankylosing spondylitis, respectively. {sup 213}Bi and {sup 211}At were attached to monoclonal antibodies and used as targeted immunotherapeutic agents while unconjugated {sup 224}Ra chloride selectively seeks bone. {sup 225}Ac possesses favorable physical properties for radioimmunotherapy (10 d half-life and 4 net alpha particles), but has a history of unfavorable radiolabeling chemistry and poor metal-chelate stability. We selected functionalized derivatives of DOTA as the most promising to pursue from out of a group of potential {sup 225}Ac chelate compounds. A two-step synthetic process employing either MeO-DOTA-NCS or 2B-DOTA-NCS as the chelating moiety was developed to attach {sup 225}Ac to monoclonal antibodies. This method was tested using several different IgG systems. The chelation reaction yield in the first step was 93{+-}8% radiochemically pure (n=26). The second step yielded {sup 225}Ac-DOTA-IgG constructs that were 95{+-}5% radiochemically pure (n=27) and the mean percent immunoreactivity ranged from 25% to 81%, depending on the antibody used. This process has yielded several potential novel targeted {sup 225}Ac-labeled immunotherapeutic agents that may now be evaluated in appropriate model systems and ultimately in humans.

Inhibition of acrolein-stimulated MUC5AC expression by Platycodon grandiflorum root-derived saponin in A549 cells.

Science.gov (United States)

Choi, Jae Ho; Hwang, Yong Pil; Han, Eun Hee; Kim, Hyung Gyun; Park, Bong Hwan; Lee, Hyun Sun; Park, Byung Keun; Lee, Young Chun; Chung, Young Chul; Jeong, Hye Gwang

2011-09-01

Mucin overproduction is a hallmark of chronic airway diseases such as chronic obstructive pulmonary disease. In this study, we investigated the inhibition of acrolein-induced expression of mucin 5, subtypes A and C (MUC5AC) by Changkil saponin (CKS) in A549 cells. Acrolein, a known toxin in tobacco smoke and an endogenous mediator of oxidative stress, increases the expression of airway MUC5AC, a major component of airway mucus. CKS, a Platycodon grandiflorum root-derived saponin, inhibited acrolein-induced MUC5AC expression and activity, through the suppression of NF-κB activation. CKS also repressed acrolein-induced phosphorylation of ERK1/2, JNK1/2, and p38MAPK, which are upstream signaling molecules that control MUC5AC expression. In addition, the MAPK inhibitors PD98059 (ERK1/2), SP600125 (JNK1/2), and SB203580 (p38 MAPK), and a PKC delta inhibitor (rottlerin; PKCδ) inhibited acrolein-induced MUC5AC expression and activity. CKS repressed acrolein-induced phosphorylation of PKCδ. Moreover, a reactive oxygen species (ROS) inhibitor, N-acetylcysteine, inhibited acrolein-induced MUC5AC expression and activity through the suppression of PKCδ and MAPK activation, and CKS repressed acrolein-induced ROS production. These results suggest that CKS suppresses acrolein-induced MUC5AC expression by inhibiting the activation of NF-κB via ROS-PKCδ-MAPK signaling. Copyright © 2011 Elsevier Ltd. All rights reserved.

Implementation of nuclear power plant simulation in start-up commissioning of reactor control system

International Nuclear Information System (INIS)

Yang Zongwei; Huang Tieming; Feng Guangyu; Luan Zhenhua; Lin Meng; Zhu Lizhi

2009-01-01

Based on the nuclear power thermal-hydraulic model, Labview graphical programming language and virtual instrument data acquisition technology, this paper describes a dedicate test platform to solve the problem that the reactor control system (RRC) can not be evaluated and analyzed far before the actual startup of the unit. By connecting the test platform to the nuclear Digital Control System (DCS), the step-by-step closed-looped test and global function test of RRC system were performed, the dynamic validation and logical function demonstration for RRC were realized, and a lot of configuration mistakes of RRC and nonconformity were solved. The test for unit 3 of Ling'ao phase II has proved that the implementation of nuclear power plant simulation in the start-up commissioning of RRC can greatly reduce the risk of normal power operation and great transient tests, with which the term of startup for overall unit test can be greatly shortened. (authors)

Influence of AC system design on the realisation of tractive efforts by high adhesion locomotives

Science.gov (United States)