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Sample records for impedance controlled llrf

  1. Selecting RF Amplifiers for Impedance Controlled LLRF Systems - Nonlinear Effects and System Implications

    Energy Technology Data Exchange (ETDEWEB)

    Fox, John D.; Mastorides, Themis; Rivetta, Claudio Hector; Van Winkle, Daniel; /SLAC

    2007-07-06

    Several high-current accelerators use feedback techniques in the accelerating RF systems to control the impedances seen by the circulating beam. These Direct and Comb Loop architectures put the high power klystron and LLRF signal processing components inside feedback loops, and the ultimate behavior of the systems depends on the individual sub-component properties. Imperfections and non-idealities in the signal processing leads to reduced effectiveness in the impedance control loops. In the PEP-II LLRF systems non-linear effects have been shown to reduce the achievable beam currents, increase low-mode longitudinal growth rates and reduce the margins and stability of the LLRF control loops. We present measurements of the driver amplifiers used in the PEP-II systems, and present measurement techniques needed to quantify the small-signal gain, linearity, transient response and image frequency generation of these amplifiers.

  2. The Test of LLRF control system on superconducting cavity

    CERN Document Server

    Zhu, Zhenglong; Wen, Lianghua; Chang, Wei; Zhang, Ruifeng; Gao, Zheng; Chen, Qi

    2014-01-01

    The first generation Low-Level radio frequency(LLRF) control system independently developed by IMPCAS, the operating frequency is 162.5MHz for China ADS, which consists of superconducting cavity amplitude stability control, phase stability control and the cavity resonance frequency control. The LLRF control system is based on four samples IQ quadrature demodulation technique consisting an all-digital closed-loop feedback control. This paper completed the first generation of ADS LLRF control system in the low-temperature superconducting cavities LLRF stability and performance online tests. Through testing, to verify the performance of LLRF control system, to analysis on emerging issues, and in accordance with the experimental data, to summarize LLRF control system performance to accumulate experience for the future control of superconducting cavities.

  3. Digital LLRF controller for NICA booster

    Science.gov (United States)

    Fatkin, G. A.; Batrakov, A. M.; Ilyin, I. V.; Vasilyev, M. Yu.

    2016-10-01

    The digital LLRF controller based on embedded microcontroller for the booster of the Dubna superconducting accelerator complex NICA is presented. It allows setting the frequency in accordance with the magnetic field value in the 0.5-5 MHz range with an inaccuracy ± 110 Hz. A novel method of frequency calculation based on the derivative is proposed. The specialized tester module allows tuning up and checking the RF system during comissioning and operation.

  4. Feedback linearization application for LLRF control system

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.

    1999-06-01

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. This paper addresses the problem of the LLRF control system for LEDA. The authors propose a control law which is based on exact feedback linearization coupled with gain scheduling which reduces the effect of the deterministic klystron cathode voltage ripple that is due to harmonics of the high voltage power supply and achieves tracking of desired set points. Also, they propose an estimator of the ripple and its time derivative and the estimates based feedback linearization controller.

  5. Feedback linearization application for LLRF control system

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, S.; Regan, A.; Wang, Y.M.; Rohlev, T.

    1998-12-31

    The Low Energy Demonstration Accelerator (LEDA) being constructed at Los Alamos National Laboratory will serve as the prototype for the low energy section of Acceleration Production of Tritium (APT) accelerator. This paper addresses the problem of the LLRF control system for LEDA. The authors propose a control law which is based on exact feedback linearization coupled with gain scheduling which reduces the effect of the deterministic klystron cathode voltage ripple that is due to harmonics of the high voltage power supply and achieves tracking of desired set points. Also, they propose an estimator of the ripple and its time derivative and the estimates based feedback linearization controller.

  6. Digital control in LLRF system for CYCIAE-100 cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Zhiguo, E-mail: bitbearAT@hotmail.com; Fu, Xiaoliang; Ji, Bin; Zhang, Tianjue; Wang, Chuan

    2016-05-21

    As a driven accelerator, the CYCIAE-100 cyclotron is designed by China Institute of Atomic Energy for the Beijing Radio Ion-beam Facility project. The cyclotron RF system is designed to use two RF power sources of 100 kW to drive two half-wavelength cavities respectively. Two Dee accelerating electrodes are kept separately from each other inside the cyclotron, while their accelerating voltages are maintained in phase by the efforts of LLRF control. An analog–digital hybrid LLRF system has been developed to achieve cavity tuning control, dee voltage amplitude and phase stabilization etc. The analog subsystems designs are focused on RF signal up/down conversion, tuning control, and dee voltage regulation. The digital system provides an RF signal source, aligns the cavity phases and maintains a Finite State Machine. The digital parts combine with the analog functions to provide the LLRF control. A brief system hardware introduction will be given in this paper, followed by the review of several major characteristics of the digital control in the 100 MeV cyclotron LLRF system. The commissioning is also introduced, and most of the optimization during the process was done by changing the digital parts.

  7. Digital control in LLRF system for CYCIAE-100 cyclotron

    Science.gov (United States)

    Yin, Zhiguo; Fu, Xiaoliang; Ji, Bin; Zhang, Tianjue; Wang, Chuan

    2016-05-01

    As a driven accelerator, the CYCIAE-100 cyclotron is designed by China Institute of Atomic Energy for the Beijing Radio Ion-beam Facility project. The cyclotron RF system is designed to use two RF power sources of 100 kW to drive two half-wavelength cavities respectively. Two Dee accelerating electrodes are kept separately from each other inside the cyclotron, while their accelerating voltages are maintained in phase by the efforts of LLRF control. An analog-digital hybrid LLRF system has been developed to achieve cavity tuning control, dee voltage amplitude and phase stabilization etc. The analog subsystems designs are focused on RF signal up/down conversion, tuning control, and dee voltage regulation. The digital system provides an RF signal source, aligns the cavity phases and maintains a Finite State Machine. The digital parts combine with the analog functions to provide the LLRF control. A brief system hardware introduction will be given in this paper, followed by the review of several major characteristics of the digital control in the 100 MeV cyclotron LLRF system. The commissioning is also introduced, and most of the optimization during the process was done by changing the digital parts.

  8. Sub-LSB DAC resolution enhancement applied to LLRF control.

    CERN Document Server

    Grecki, M

    2010-01-01

    The digital control systems use the ADCs/DACs as a front-end for analogue signals processing. The paper proposes the solution to enhance the DAC resolution by PWM. The modulation scheme is optimized to the parameters of of LLRF control in FLASH accelerator. For that purpose the genetic algorithm was implemented and applied. The distributed computing was used to speed-up the computations.

  9. Design and development progress of a LLRF control system for a 500 MHz superconducting cavity

    Science.gov (United States)

    Lee, Y. S.; Kim, H. W.; Song, H. S.; Lee, J. H.; Park, K. H.; Yu, I. H.; Chai, J. S.

    2012-07-01

    The LLRF (low-level radio-frequency) control system which regulates the amplitude and the phase of the accelerating voltage inside a RF cavity is essential to ensure the stable operation of charged particle accelerators. Recent advances in digital signal processors and data acquisition systems have allowed the LLRF control system to be implemented in digitally and have made it possible to meet the higher demands associated with the performance of LLRF control systems, such as stability, accuracy, etc. For this reason, many accelerator laboratories have completed or are completing the developments of digital LLRF control systems. The digital LLRF control system has advantages related with flexibility and fast reconfiguration. This paper describes the design of the FPGA (field programmable gate array) based LLRF control system and the status of development for this system. The proposed LLRF control system includes an analog front-end, a digital board (ADC (analog to digital converter), DAC (digital to analog converter), FPGA, etc.) and a RF & clock generation system. The control algorithms will be implemented by using the VHDL (VHSIC (very high speed integrated circuits) hardware description language), and the EPICS (experiment physics and industrial control system) will be ported to the host computer for the communication. In addition, the purpose of this system is to control a 500 MHz RF cavity, so the system will be applied to the superconducting cavity to be installed in the PLS storage ring, and its performance will be tested.

  10. Design and Realization of Frequency Tuning System for LLRF Control System

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    <正>1 Purpose of design The 44 MHz RF control system is important to the experiment on metal model cavity. The frequency tuning system is designed as a part of LLRF control system, intending to synchronize the frequency of

  11. Impedance Scaling and Impedance Control

    Energy Technology Data Exchange (ETDEWEB)

    Chou, W.; Griffin, J.

    1997-06-01

    When a machine becomes really large, such as the Very Large Hadron Collider (VLHC), of which the circumference could reach the order of megameters, beam instability could be an essential bottleneck. This paper studies the scaling of the instability threshold vs. machine size when the coupling impedance scales in a ``normal`` way. It is shown that the beam would be intrinsically unstable for the VLHC. As a possible solution to this problem, it is proposed to introduce local impedance inserts for controlling the machine impedance. In the longitudinal plane, this could be done by using a heavily detuned rf cavity (e.g., a biconical structure), which could provide large imaginary impedance with the right sign (i.e., inductive or capacitive) while keeping the real part small. In the transverse direction, a carefully designed variation of the cross section of a beam pipe could generate negative impedance that would partially compensate the transverse impedance in one plane.

  12. Synchronic, optical transmission data link integrated with FPGA circuits (for TESLA LLRF control system)

    Energy Technology Data Exchange (ETDEWEB)

    Zielinski, J.S.

    2006-07-15

    The X-ray free-electron laser X-FEL that is being planned at the DESY research center in cooperation with European partners will produce high-intensity ultra-short X-ray flashes with the properties of laser light. This new light source, which can only be described in terms of superlatives, will open up a whole range of new possibilities for the natural sciences. It could also offer very promising opportunities for industrial users. SIMCON (SIMulator and CONtroller) is the project of the fast, low latency digital controller dedicated to the LLRF1 system in VUV FEL experiment It is being developed by the ELHEP2 group in the Institute of Electronic Systems at Warsaw University of Technology. The main purpose of the project is to create a controller to stabilize the vector sum of fields in cavities of one cryo-module in the experiment. The device can be also used as the simulator of the cavity and test bench for other devices. The synchronic, optical link project was made for the accelerator X-FEL laser TESLA, the LLRF control system experiment at DESY, Hamburg. The control and diagnostic data is transmitted up to 2.5Gbit/s through a plastic fiber in a distance up to a few hundred meters. The link is synchronized once after power up, and never resynchronized when data is transmitted with maximum speed. The one way link bit error rate is less then 10{sup -15}. The transceiver component written in VHDL that works in the dedicated Altera registered Stratix registered GX FPGA circuit. During the work in the PERG laboratory a 2,5Gbit/s serial link with the long vector parallel interface transceiver was created. Long-Data-Vector transceiver transmits 16bit vector each 8ns with 120ns latency. (orig.)

  13. LLRF Control of High Loaded-Q Cavities for the LCLS-II

    Energy Technology Data Exchange (ETDEWEB)

    Serrano, Carlos [LBNL, Berkeley; Babel, Sandeep [SLAC; Bachimanchi, Ramakrishna [Jefferson Lab; Boyes, Matt [SLAC; Chase, Brian [Fermilab; Cullerton, Ed [Fermilab; Doolittle, Lawrence [LBNL, Berkeley; Einstein, Joshua [Fermilab; Hong, Bo [SLAC; Hovater, Curt [Jefferson Lab; Huang, Gang [LBNL, Berkeley; Ratti, Alessandro [LBNL, Berkeley

    2016-06-01

    The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW Superconducting Radio Frequency (SCRF) linac. The nature of the machine places stringent requirements in the Low-Level RF (LLRF) system, expected to control the cavity fields within 0.01 degrees in phase and 0.01% in amplitude, which is equivalent to a longitudinal motion of the cavity structure in the nanometer range. This stability has been achieved in the past but never for hundreds of superconducting cavities in Continuous-Wave (CW) operation. The difficulty resides in providing the ability to reject disturbances from the cryomodule, which is incompletely known as it depends on the cryomodule structure itself (currently under development at JLab and Fermilab) and the harsh accelerator environment. Previous experience in the field and an extrapolation to the cavity design parameters (relatively high Q_{L}c≈ 4×10⁷ , implying a half-bandwidth of around 16 Hz) suggest the use of strong RF feedback to reject the projected noise disturbances, which in turn demands careful engineering of the entire system.

  14. Lessons Learned from PEP-II LLRF and Longitudinal Feedback

    Energy Technology Data Exchange (ETDEWEB)

    Fox, J.D.; Mastorides, T.; Rivetta, C.H.; Van Winkle, D.; /SLAC; Teytelman, D.; /Dimtel, Redwood City

    2010-08-26

    The PEP-II B-Factory collider ended the final phase of operation at nearly twice the design current and 4X the design luminosity. To highlight the evolution from the original conceptual design through to the 1.2E34 final machine we choose one example each from the broadband feedback and from the LLRF system. They illustrate the original design estimation missed some very significant details, and how in the course of PEP-II operation unexpected difficulties led to significant insights and new approaches which allowed higher machine performance. We present valuable 'lessons learned' which are of interest to designers of next generation feedback and impedance controlled LLRF systems.

  15. A vector control and data acquisition system for the multicavity LLRF system for cryomodule1 at Fermilab

    CERN Document Server

    Varghese, P; Barnes, B; Branlard, J; Cullerton, E; Joireman, P; Tupikov, V

    2012-01-01

    A LLRF control and data acquisition system for the 8-cavity cryomodule1 at the ILCTA has been implemented using three 33-channel ADC boards in a VXI mainframe. One card each is dedicated to the cavity probes for vector control, forward power and reverse power measurements. The system is scalable to 24 cavities or more with the commissioning of cryomodules 2 and 3 without additional hardware. The signal processing and vector control of the cavities is implemented in an FPGA and a high speed data acquisition system with up to 100 channels which stores data in external SDRAM memory. The system supports both pulsed and CW modes with a pulse rate of 5 Hz. Acquired data is transferred between pulses to auxiliary systems such as the piezo controller through the VXI slot0 controller. The performance of the vector control system is evaluated and the design of the system is described.

  16. PSB LLRF renovation: Initial beam tests of the new digital beam control system

    CERN Document Server

    Angoletta, ME; Butterworth, A; Findlay, A; Pedersen, F; CERN. Geneva. BE Department

    2009-01-01

    The beam control renovation project for CERN’s PS Booster (PSB) was started in autumn 2008. Its aim is to equip all four PSB rings with modern digital beam control systems, characterised by fully-PPM parameters and complete remote control. Additionally, all intermediate and input/output signals are to be remotely acquired in a digital way and in full PPM fashion, and displayed via the Oasis application program. The same digital technology concepts have already been successfully applied to the LEIR beam control system, which has acted as a pilot project for the whole PS Complex renovation project. This new technology allows a very flexible performance and can improve the system maintainability by becoming the standard for the PS Complex beam controls. This note details the first step in the PSB consolidation project, namely the beam control prototype tests carried out on PSB ring 4 in October and November 2008. Both C02 and C04 RF system have been successfully controlled; bunch splitting and extraction synch...

  17. Controls, LLRF, and instrumentation systems for ILC test facilities at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Chase, B.; Votava, M.; Wendt, M.; /Fermilab

    2007-06-01

    The major controls and instrumentation systems for the ILC test areas and the NML test accelerator at Fermilab are discussed. The test areas include 3 separate areas for Vertical Superconducting RF Cavity Testing, Horizontal Cavity Testing, and NML RF and beam test area. A common control infrastructure for the test areas including a controls framework, electronic logbook and cavity database will be provided, while supporting components supplied by collaborators with diverse areas of expertise (EPICS, DOOCS, LabVIEW, and Matlab). The discussions on the instrumentation systems are focused on overview and requirements.

  18. LLRF System for the CEBAF Separator Upgrade

    Energy Technology Data Exchange (ETDEWEB)

    Plawski, Tomasz E. [JLAB; Bachimanchi, Ramakrishna [JLAB; Hovater, J. Curt [JLAB; Seidman, David J. [JLAB; Wissmann, Mark J. [JLAB

    2014-12-01

    The Continuous Electron Beam Accelerator Facility (CEBAF) energy upgrade from 6 GeV to 12 GeV includes the installation of four new 748.5 MHz normal conducting deflecting cavities in the 5th pass extraction region. This system will work together with the existing 499 MHz RF Separator in order to allow simultaneous delivery of the beam to four CEBAF experimental halls. The RF system employs two digital LLRF systems controlling four cavities in a vector sum. Cavity tune information of the individual cavities is also obtained using a multiplexing scheme of the forward and reflected RF signals. In this paper we will present detailed LLRF design and the current status of the CEBAF 748.5/499 MHz beam extraction system.

  19. Development of a finite state machine for the automates operation of the LLRF control at FLASH

    Energy Technology Data Exchange (ETDEWEB)

    Brandt, A.

    2007-07-15

    The entry of digital signal processors in modern control systems not only allows for extended diagnostics compared to analog systems but also for sophisticated and tricky extensions of the control algorithms. With modern DSP- and FPGA-technology, the processing speed of digital systems is no longer inferior to analog systems in many applications. A higher degree of digitalization leads to an increased complexity of the systems and hence to higher requirements on their operators. The focus of research and development in the field of high frequency control has changed in the last few years and moved towards the direction of software development and complexity management. In the presented thesis, a frame for an automation concept of modern high frequency control systems is developed. The developed automation is based on the concept of finite state machines (FSM), which is established in industry for years. A flexible framework was developed, in which procedures communicate using standardized interfaces and can be exchanged easily. With that, the developer of high frequency control components as well as the operator on shift shall be empowered to improve and adapt the automation to changed conditions without special programming skills required. Along the automation concept a number of algorithms addressing various problems were developed which satisfy the needs of modern high frequency control systems. Among the developed and successfully tested algorithms are the calibration of incident and reflected wave of resonators without antennas, the fast adaptive compensation of repetitive errors, the robust estimation of the phase advance in the control loop and the latency adjustment for the rejection of instabilities caused by passband modes. During the development of the resonator theory, high value was set on the usability of the equation in algorithms for high frequency control. The usage of the common nomenclature of control theory emphasizes the underlying mathematical

  20. SIMCON 3.1. LLRF system control board measurements (for TESLA Test Facility)

    Energy Technology Data Exchange (ETDEWEB)

    Pietrasik, R.

    2006-07-15

    The SIMCON control systems for superconducting cavity resonators are described. These systems consist of analog and digital I/O systems, a clock system, an Ethernet link, optical input systems, a RS232 interface, a VME section with booting FPGA devices, and a Virtex2Pro section. The measurements of different parameters by this system are described. (HSI)

  1. Modular version of SIMCON, FPGA based, DSP integrated, LLRF control system for TESLA FEL part I: SIMCON 3.0 motherboard

    Science.gov (United States)

    Pozniak, Krzysztof T.; Romaniuk, Ryszard S.; Kierzkowski, Krzysztof

    2006-03-01

    The paper includes a description of predicted functionalities to be implemented in a universal motherboard (MB) for the next generation of LLRF control system for TESLA. The motherboard bases on a number of quasi-autonomous embedded executive modules. The modules are implemented in a few FPGA chips featured by the MB. The paper presents a practical design of the MB. The initial (basic) solution of the MB has the Cyclone as the chip where the board management is embedded. The board features communication modules - VME and micro, single chip PC with Ethernet. The board provides power supply for the FPGA chips. The board has fast internal communication between particular modules. The described Motherboard serves for experiments with the SIMCON 3.0 system.

  2. CERN PSB Beam Tests of CNAO Synchrotron's Digital LLRF

    CERN Document Server

    Angoletta, M E; De Martinis, C; Falbo, L; Findlay, A; Foglio, R; Hunt, S; Tourres, D; Vescovi, C

    2008-01-01

    The Italian National Centre for Oncological hAdrontherapy (CNAO), in its final construction phase, uses proton and carbon ion beams to treat patients affected by solid tumours. At the heart of CNAO is a 78- meter circumference synchrotron that accelerates particles to up to 400 MeV/u. The synchrotron relies on a digital LLRF system based upon Digital Signal Processors (DSPs) and Field Programmable Gate Array (FPGA). This system implements cavity servoing and beam control capabilities, such as phase and radial loops. Beam tests of the CNAO synchrotron LLRF system were carried out at CERN's Proton Synchrotron Booster (PSB) in autumn 2007, to verify the combined DSP/FPGA architecture and the beam control capabilities. For this, a prototype version of CNAO's LLRF system was adapted to the PSB requirements. This paper outlines the prototype system layout and describes the tests carried out and their results. In particular, system architecture and beam control capabilities were successfully proven by comparison wit...

  3. A spatial impedance controller for robotic manipulation

    NARCIS (Netherlands)

    Fasse, Ernest D.; Broenink, Jan F.

    1997-01-01

    Mechanical impedance is the dynamic generalization of stiffness, and determines interactive behavior by definition. Although the argument for explicitly controlling impedance is strong, impedance control has had only a modest impact on robotic manipulator control practice. This is due in part to the

  4. The LCLS-II LLRF System

    Energy Technology Data Exchange (ETDEWEB)

    DooLittle, Lawrence [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Huang, G. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Ratti, A. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Serrano, C. [Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States); Bachimanchi, Ramakrishna [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Hovater, J. Curt [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Babel, S. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Hong, B. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Van Winkle, D. [SLAC National Accelerator Lab., Menlo Park, CA (United States); Chase, B. [Fermi National Accelerator Lab. (FNAL), Batavia, IL (United States); Cullerton, E. [FNAL, Batavia, IL; Varghese, P. [FNAL, Batavia, IL

    2015-09-01

    The SLAC National Accelerator Laboratory is planning an upgrade (LCLS-II) to the Linear Coherent Light Source with a 4 GeV CW superconducting (SCRF) linac. The SCRF linac consists of 35 ILC style cryomodules (eight cavities each) for a total of 280 cavities. Expected cavity gradients are 16 MV/m with a loaded QL of ~ 4x107. The RF system will have 3.8 kW solid state amplifiers driving single cavities. To ensure optimum field stability a single-source single-cavity control system has been chosen. It consists of a precision four-channel cavity receiver and RF stations (Forward, Reflected and Drive signals). In order to regulate the resonant frequency variations of the cavities due to He pressure, the tuning of each cavity is controlled by a Piezo actuator and a slow stepper motor. In addition the system (LLRF-amplifier-cavity) is being modeled and cavity microphonic testing has started. This paper describes the LLRF system under consideration, including recent modeling and cavity tests.

  5. A hardware overview of the RHIC LLRF platform

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, T.; Smith, K.S.

    2011-03-28

    The RHIC Low Level RF (LLRF) platform is a flexible, modular system designed around a carrier board with six XMC daughter sites. The carrier board features a Xilinx FPGA with an embedded, hard core Power PC that is remotely reconfigurable. It serves as a front end computer (FEC) that interfaces with the RHIC control system. The carrier provides high speed serial data paths to each daughter site and between daughter sites as well as four generic external fiber optic links. It also distributes low noise clocks and serial data links to all daughter sites and monitors temperature, voltage and current. To date, two XMC cards have been designed: a four channel high speed ADC and a four channel high speed DAC. The new LLRF hardware was used to replace the old RHIC LLRF system for the 2009 run. For the 2010 run, the RHIC RF system operation was dramatically changed with the introduction of accelerating both beams in a new, common cavity instead of each ring having independent cavities. The flexibility of the new system was beneficial in allowing the low level system to be adapted to support this new configuration. This hardware was also used in 2009 to provide LLRF for the newly commissioned Electron Beam Ion Source.

  6. Cartesian impedance control of dexterous robot hand

    Institute of Scientific and Technical Information of China (English)

    JIANG Li; LIU Hong; CAI He-gao

    2005-01-01

    Presents a novel compliant motion control for a robot hand using the Cartesian impedance approach based on fingertip force measurements. The fingertip can accurately track desired motion in free space and appear as mechanical impedance in constrained space. In the position based impedance control strategy, any switching mode in contact transition phase is not needed. The impedance parameters can be adjusted in a certain range according to various tasks. In this paper, the analysis of the finger's kinematics and dynamics is given. Experimental results have shown the effectiveness of this control strategy.

  7. Concept and architecture of the RHIC LLRF upgrade platform

    Energy Technology Data Exchange (ETDEWEB)

    Smith, K.S.; Hayes, T.; Severino, F.

    2011-03-28

    The goal of the RHIC LLRF upgrade has been the development of a stand alone, generic, high performance, modular LLRF control platform, which can be configured to replace existing systems and serve as a common platform for all new RF systems. The platform is also designed to integrate seamlessly into a distributed network based controls infrastructure, be easy to deploy, and to be useful in a variety of digital signal processing and data acquisition roles. Reuse of hardware, software and firmware has been emphasized to minimize development effort and maximize commonality of system components. System interconnection, synchronization and scaling are facilitated by a deterministic, high speed serial timing and data link, while standard intra and inter chassis communications utilize high speed, non-deterministic protocol based serial links. System hardware configuration is modular and flexible, based on a combination of a main carrier board which can host up to six custom or commercial daughter modules as required to implement desired functionality. This paper will provide an overview of the platform concept, architecture, features and benefits. The RHIC LLRF Upgrade Platform has been developed with the goal of providing a flexible, modular and scalable architecture which will support our current applications and satisfy new ones for the foreseeable future. The platform has been recently commissioned at both RHIC and the RHIC EBIS injector. To date the platform has demonstrated its versatility and utility, meeting the design goals as originally defined.

  8. The LEIR LLRF DSP-Carrier Board : Performance, CPS Renovation Plan and Recommendations

    CERN Document Server

    Angoletta, M E

    2007-01-01

    The LEIR LLRF project started in late 2003 and included designing,manufacturing and commissioning a novel, all-digital beam control system. The project was first to provide the LEIR machine with a beam control system satisfying the many performance requirements. This was achieved in 2006 with the successful LEIR LLRF system commissioning. In addition, the project was to act as a pilot to export the same technology to the other machines of the PS Complex (CPS), such as PS, PSB and AD. New machines currently being proposed (e.g. ELENA) will also rely on it. The evaluation of the LEIR experience and the recommendations on how to best pursue this migration strategy are therefore integral parts of the LEIR LLRF project. A fundamental building block of the LEIR LLRF system is the DSP-carrier board where all beam control loops are implemented. This note examines the main features of the DSP-carrier board release 1.0 used in LEIR and evaluates their impact on the LEIR LLRF implementation and operational performance. ...

  9. Impedance Control of a Redundant Parallel Manipulator

    DEFF Research Database (Denmark)

    Méndez, Juan de Dios Flores; Schiøler, Henrik; Madsen, Ole

    2017-01-01

    This paper presents the design of Impedance Control to a redundantly actuated Parallel Kinematic Manipulator. The proposed control is based on treating each limb as a single system and their connection through the internal interaction forces. The controller introduces a stiffness and damping matr...

  10. SYSTEM IDENTIFICATION OF THE LINAC RF SYSTEM USING A WAVELET METHOD AND ITS APPLICATIONS IN THE SNS LLRF CONTROL SYSTEM

    Energy Technology Data Exchange (ETDEWEB)

    Y. WANG; S. KWON; ET AL

    2001-06-01

    For a pulsed LINAC such as the SNS, an adaptive feed-forward algorithm plays an important role in reducing the repetitive disturbance caused by the pulsed operation conditions. In most modern feed-forward control algorithms, accurate real time system identification is required to make the algorithm more effective. In this paper, an efficient wavelet method is applied to the system identification in which the Haar function is used as the base wavelet. The advantage of this method is that the Fourier transform of the Haar function in the time domain is a sine function in the frequency domain. Thus we can directly obtain the system transfer function in the frequency domain from the coefficients of the time domain system response.

  11. Impedance Based Analysis and Design of Harmonic Resonant Controller for a Wide Range of Grid Impedance

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Blaabjerg, Frede

    2014-01-01

    in the closed-loop output admittance of converter. Such negative resistances may interact with the grid impedance resulting in steady state error or unstable harmonic compensation. To deal with this problem, a design guideline for harmonic resonant controllers under a wide range of grid impedance is proposed......This paper investigates the effect of grid impedance variation on harmonic resonant current controllers for gridconnected voltage source converters by means of impedance-based analysis. It reveals that the negative harmonic resistances tend to be derived from harmonic resonant controllers...

  12. LHC and CLIC LLRF final reports

    CERN Document Server

    Dexter, A; Woolley, B; Ambattu, P; Tahir, I; Syratchev, Igor; Wuensch, Walter

    2013-01-01

    Crab cavities rotate bunches from opposing beams to achieve effective head-on collision in CLIC or collisions at an adjustable angle in LHC. Without crab cavities 90% of achievable luminosity at CLIC would be lost. In the LHC, the crab cavities allow the same or larger integrated luminosity while reducing significantly the requested dynamic range of physics detectors. The focus for CLIC is accurate phase synchronisation of the cavities, adequate damping of wakefields and modest amplitude stability. For the LHC, the main LLRF issues are related to imperfections: beam offsets in cavities, RF noise, measurement noise in feedback loops, failure modes and mitigations. This report develops issues associated with synchronising the CLIC cavities. It defines an RF system and experiments to validate the approach. It reports on the development of hardware for measuring the phase performance of the RF distributions system and cavities. For the LHC, the hardware being very close to the existing LLRF, the report focuses on...

  13. GUI Application for ATCA-based LLRF Carrier Board Management

    CERN Document Server

    Wychowaniak, Jan; Predki, Pawel; Napieralski, Andrzej

    2011-01-01

    The Advanced Telecommunications Computing Architecture (ATCA) standard describes an efficient and powerful platform, implementation of which was adopted to be used as a base for control systems in high energy physics. The ATCA platform is considered to be applied for the X-ray Free Electron Laser (X-FEL), being built at Deutsches Electronen- Synchrotron (DESY) in Hamburg, Germany. The Low Level Radio Frequency (LLRF) control system is composed of a few ATCA Carrier Boards. Carrier Board hosts Intelligent Platform Management Controller (IPMC), which is developed in compliance with the PICMG specifications. IPMC is responsible for management and monitoring of sub-modules installed on Carrier Boards and pluggable Advanced Mezzanine Card (AMC) modules. The ATCA Shelf Manager is the main control unit of a single ATCA crate, responsible for all power and fan modules and Carrier Boards installed in ATCA shelf. The device provides a system administrator with a set of control and diagnostic capabilities regarding the ...

  14. CERN's LEIR Digital LLRF : system overview and operational experience

    CERN Document Server

    Angoletta, ME; Blas, A; Bracke, E; Butterworth, A; Dubouchet, F; Findlay, A; Pedersen, F; Sanchez-Quesada, J

    2010-01-01

    The Low Energy Ion Ring (LEIR) is an accumulation and acceleration ring in the Large Hadron Collider (LHC) ion injector chain. After its successful start in 2005, it has been running in three operational campaigns. The LEIR low-level RF (LLRF) system is the first all-digital system to operate in a CERN circular machine. Its capabilities include beam control tasks as well as dual-harmonic cavity voltage/phase servoing. All the system’s control parameters are fully configurable, remotely and in-between cycles; extensive built-in observation capabilities and diagnostics are available. The system is flexible, powerful and extremely reliable. This paper outlines the main building blocks and operational features, along with results obtained during the first years of operation.

  15. 13 CFR 120.847 - Requirements for the Loan Loss Reserve Fund (LLRF).

    Science.gov (United States)

    2010-01-01

    ... Requirements for the Loan Loss Reserve Fund (LLRF). (a) General. PCLP CDCs must establish and maintain a LLRF... 13 Business Credit and Assistance 1 2010-01-01 2010-01-01 false Requirements for the Loan Loss Reserve Fund (LLRF). 120.847 Section 120.847 Business Credit and Assistance SMALL BUSINESS...

  16. Design approaches for the X band LLRF system

    Energy Technology Data Exchange (ETDEWEB)

    Mavric, Uros, E-mail: uros@i-tech.si [Instrumentation Technologies, Velika pot 22, Solkan 5250 (Slovenia); Jug, Gasper [Instrumentation Technologies, Velika pot 22, Solkan 5250 (Slovenia)

    2011-11-21

    The low-level RF (LLRF) system regulates disturbances over a limited bandwidth in accordance with its capabilities and the RF loop parameters. The disturbances usually originate in the RF system or can be coupled to the RF system from the environment. In this paper a general overview of the possible design approaches for a digital LLRF system operating in X band is presented. Firstly, the possible design approaches of the RF front/back ends are presented and reviewed. We also define the main design parameters for the RF front/back ends. Parameters like isolation between channels, noise, gain, linearity and number of IF stages are put into the perspective of machines using RF components in the X band. An important part of the LLRF system is the local RF timing generation and distribution, which is also treated in the paper. In the second part of the paper the main design approaches in the digital signal processing part of the LLRF system are presented. The emphasis is on the algorithms that are machine specific. Some standard processing algorithms like adaptive feed-forward and arbitrary shaping of feed-forward pulses are presented. Finally, a suggestion for the X band LLRF design is given.

  17. Object impedance control for cooperative manipulation - Theory and experimental results

    Science.gov (United States)

    Schneider, Stanley A.; Cannon, Robert H., Jr.

    1992-01-01

    This paper presents the dynamic control module of the Dynamic and Strategic Control of Cooperating Manipulators (DASCCOM) project at Stanford University's Aerospace Robotics Laboratory. First, the cooperative manipulation problem is analyzed from a systems perspective, and the desirable features of a control system for cooperative manipulation are discussed. Next, a control policy is developed that enforces a controlled impedance not of the individual arm endpoints, but of the manipulated object itself. A parallel implementation for a multiprocessor system is presented. The controller fully compensates for the system dynamics and directly controls the object internal forces. Most importantly, it presents a simple, powerful, intuitive interface to higher level strategic control modules. Experimental results from a dual two-link-arm robotic system are used to compare the object impedance controller with other strategies, both for free-motion slews and environmental contact.

  18. Does polyandrous impede mosquito control by autocidal?

    Directory of Open Access Journals (Sweden)

    K.Jayaprakash

    2014-03-01

    Full Text Available Vector mosquito control by releasing genetically altered males has been attempted under the presumption that the females are monandrous. The present observation was through the sex–linked inheritance pattern of eye-colour and the estimation of polyandrous in in-vitro mating. A small proportion (18.2% of the female Anopheles stephensi population exhibited polyandrous on examination of 850 F1 adults when two types of males (white and black eyed where allowed to mate with homozygous white eyed females. The above results were discussed with relation to the consequences of the polyandrous trait in sterile insect technique, genetic control programmes.

  19. Gemstone Grinding Process Improvement by using Impedance Force Control

    Directory of Open Access Journals (Sweden)

    Hamprommarat Chumpol

    2015-01-01

    Full Text Available Chula Automatic Faceting Machine has been developed by The Advance Manufacturing Research Lab, Chulalongkorn University to support Thailand Gems-Industry. The machine has high precision motion control by using position and force control. A contact stiffness model is used to estimate grinding force. Although polished gems from the Faceting Machine have uniform size and acceptable shape, the force of the grinding and polishing process cannot be maintain constant and has some fluctuation due to indirect force control. Therefor this research work propose a new controller for this process based on an impedance direct force control to improve the gemstone grinding performance during polishing process. The grinding force can be measured through motor current. The results show that the polished gems by using impedance direct force control can maintain uniform size as well as good shape and high quality surface.

  20. Impedance control of flexible macro/mini manipulators

    Science.gov (United States)

    Schubert, Heidi Christine

    Construction and maintenance of on-orbit crew-operated hardware is currently done mostly by extra-vehicular astronauts. Use of robotics for some of these tasks provides the opportunity for both increased safety for the astronauts and major cost savings. An effective space robotic manipulator must be lightweight, have a large workspace, and be capable of fine dexterous control. A large lightweight manipulator will necessarily be quite flexible, limiting the achievable end-point bandwidth. One way to achieve all of the objectives is via advanced control of a macro/mini manipulator: a large lightweight manipulator carrying a small dexterous manipulator, such as is planned for the International Space Station. The goal of this work is to control a flexible-joint macro carrying a two-arm mini manipulator. For ease of use, a low-level controller should be designed such that the user or automated planner need only command the desired end-point motions and forces. Designing an end-point controller for a macro/mini manipulator presents many challenges. Such a manipulator system is non-linear, has low frequency flexibility, and has dynamic coupling between the macro and mini. A smart method for controlling manipulators is impedance control, which specifies a desired force-velocity relationship at the end-point of the manipulator, enabling smooth contact with the environment. Using operational space control, the dynamics of the manipulator are transformed into operational coordinates for implementation of the impedance law. The operational space method also enables a secondary control of the redundant degrees of freedom, without degrading the end-point impedance task. This thesis presents new theoretical advances that enable extending the concepts of operational space and impedance control to redundant joint-flexible robots. Important advances include a new method for choosing the end-point impedance and a null-space controller that performs much better. The new control

  1. Simulation of the Direct Digital Synthesis module for Helium RFQ LLRF system

    Energy Technology Data Exchange (ETDEWEB)

    Jeong, Hae-Seong; Ahn, Tae-Sung; Kim, Seong-Gu; Kwon, Hyeok-Jung; Kim, Han-Sung; Song, Young-Gi; Seol, Kyung-Tae; Cho, Yong-Sub [Korea Atomic Energy Research Institute, Gyeongju (Korea, Republic of)

    2015-10-15

    In this paper, the DDS module in the FPGA simulated and the analysis result will be introduced. Using Xilinx ISE design suite which is tool for developing the FPGA logic module, DDS module simulated. KOMAC (Korea Multi-purpose Accelerator Complex) has a plan to develop the helium irradiation system. This system includes the Ion source, LEBT, RFQ, MEBT systems to transport helium particles to the target. Especially, the RFQ (Radio Frequency Quadrupole) system should receive the 200 MHz RF within 1% amplitude error stability. For supplying stable 200 MHz RF to the RFQ, the LLRF (low-level radio frequency) should be controlled by control system. This helium RFQ LLRF control system have a concept to track the cavity resonance frequency. For tracking the cavity resonance frequency, the FPGA (Field Programmable Gate Array) in the digital board will tune the frequency of the output sinusoidal signal. In order to implement this frequency tracking concept, the DDS (Direct Digital Synthesis) module should be implemented in the FPGA. In the future, frequency tracking system will be tested using test cavity.

  2. Virtual-Impedance-Based Control for Voltage-Source and Current-Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Li, YunWei; Blaabjerg, Frede;

    2015-01-01

    The virtual impedance concept is increasingly used for the control of power electronic systems. Generally, the virtual impedance loop can either be embedded as an additional degree of freedom for active stabilization and disturbance rejection, or be employed as a command reference generator...... for the converters to provide ancillary services. This paper presents an overview of the virtual-impedance-based control strategies for voltage-source and current-source converters. The control output impedance shaping attained by the virtual impedances is generalized first using the impedance-based models...

  3. Whole-body impedance control of wheeled humanoid robots

    CERN Document Server

    Dietrich, Alexander

    2016-01-01

    Introducing mobile humanoid robots into human environments requires the systems to physically interact and execute multiple concurrent tasks. The monograph at hand presents a whole-body torque controller for dexterous and safe robotic manipulation. This control approach enables a mobile humanoid robot to simultaneously meet several control objectives with different pre-defined levels of priority, while providing the skills for compliant physical contacts with humans and the environment. After a general introduction into the topic of whole-body control, several essential reactive tasks are developed to extend the repertoire of robotic control objectives. Additionally, the classical Cartesian impedance is extended to the case of mobile robots. All of these tasks are then combined and integrated into an overall, priority-based control law. Besides the experimental validation of the approach, the formal proof of asymptotic stability for this hierarchical controller is presented. By interconnecting the whole-body ...

  4. Impedance Controller Tuned by Particle Swarm Optimization for Robotic Arms

    Directory of Open Access Journals (Sweden)

    Haifa Mehdi

    2011-11-01

    Full Text Available This paper presents an efficient and fast method for fine tuning the controller parameters of robot manipulators in constrained motion. The stability of the robotic system is proved using a Lyapunov‐based impedance approach whereas the optimal design of the controller parameters are tuned, in offline, by a Particle Swarm Optimization (PSO algorithm. For designing the PSOmethod,differentindexperformancesare considered in both joint and Cartesian spaces. A 3DOF manipulator constrained to a circular trajectory is finally used to validate the performances of the proposed approach. The simulation results show the stability and the performances of the proposed approach.

  5. Femoral Test Bed for Impedance Controlled Surgical Instrumentation

    Directory of Open Access Journals (Sweden)

    Christian Brendle

    2012-01-01

    Full Text Available The risk for patients during the standard procedure of revision of cemented artificial hip joints is unsatisfactorily highdue to its high level of invasiveness and limited access to the operative field. To reduce this risk we are developing anImpedance Controlled Surgical Instrumentation (ICOS system, which aims to establish real-time control during a BoneCement (BC milling process. For this, the relationship between the thickness of the BC and its frequency-dependentelectrical impedance is used to estimate the residual BC thickness. The aim is to avoid unintended cutting of boneby detecting the passage of the BC/bone boundary layer by the milling head. In a second step, an estimation of theresidual BC thickness will be used to improve process control. As a first step towards demonstrating the feasibility ofour approach, presented here are experimental studies to characterize the BC permittivity and to describe the process indetail. The results show that the permittivity properties of BC are dominated by its polymethyl methacrylate (PMMAfraction. Thus, PMMA can be used as a substitute for future experiments. Furthermore, a Femoral Test Bed (FTB wasdesigned. Using this setup we show it is feasible to accurately distinguish between slightly different thicknesses of BC.

  6. Characterization of electro-acoustics impedance and its application to active noise control

    Institute of Scientific and Technical Information of China (English)

    HOU Hong; YANG Jianhua

    2004-01-01

    Characteristics of radiation impedance and its inducing variation of electrical impedance for a controllable source have been investigated. An impedance-based error criterion has been proposed and its application to Active Noise Control is demonstrated through a coil driven loudspeaker. A general formula of radiation impedance is derived for two control strategies, according to the criterion of total acoustic power output. The radiation impedances of some commonly used sound sources are calculated. We discuss in detail the relation between variation of the input electrical impedance and radiation impedance for the two control strategies. The measured data of the input electrical impedance from a loudspeaker agree fairly well with theoretical analysis. An AC- bridge circuit is designed in order to measure the weak variation of electrical impedance resulted from radiation impedance. The bridge relative output is unique for a certain control strategy, from which an impedance-based error criterion is then proposed and the implementation of its application to an active control system is analyzed.Numerical results of such criterion are presented. An analogue control system is set up and experiments are carried out in a semi-anechoic chamber to verify the new control approach.

  7. Simulation of sliding mode impedance control for a 6 DOF antrhopomorphic robot

    NARCIS (Netherlands)

    Broenink, Jan F.; Visser, Martijn; Tiernego, Martin L.J.; Zobel, Richard; Moeller, Ditmar

    1998-01-01

    Robust control is a way of dealing with model uncertainties that can render the controller less sensitive to modelling errors and disturbances. Herein, the properties of sliding mode control are applied to impedance control to form a robust impedance con-troller. The proposed controller consists of

  8. An Update on ConSys Including a New LabVIEW FPGA Based LLRF System

    DEFF Research Database (Denmark)

    Worm, Torben; Nielsen, Jørgen S.

    ConSys, the Windows based control system for ASTRID and ASTRID2, is now a mature system, having been in operation for more than 15 years. All the standard programs (Console, plots, data logging, control setting store/restore etc.) are fully general and are configured through a database or file. Con......Sys is a standard publisher/subscriber system, where all nodes can act both as client and server. One very strong feature is the easy ability to make virtual devices (devices which do not depend on hardware directly, but combine hardware parameters.) For ASTRID2 a new LabVIEW based Low-Level RF system has been made...... live plots from the regulation loops are implemented in a host program on Windows. All three levels have been implemented with LabVIEW. The LLRF system is interfaced to ConSys through LabVIEW shared variables....

  9. Amplitude Linearizers for PEP-II 1.2 MW Klystrons and LLRF Systems

    Energy Technology Data Exchange (ETDEWEB)

    Van Winkle, D.; Browne, J.; Fox, J.D.; Mastorides, T.; Rivetta, C.; Teytelman, D.; /SLAC

    2006-07-18

    The PEP-II B-factory has aggressive current increases planned for luminosity through 2008. At 2.2A (HER) on 4A (LER) currents, we estimate that longitudinal growth rates will be comparable to the damping rates currently achieved in the existing low level RF and longitudinal feedback systems. Prior to having a good non-linear time domain model [1] it was postulated that klystron small signal gain non-linearity may be contributing to measured longitudinal growth rates being higher than linearly predicted growth rates. Five prototype klystron amplitude modulation linearizers have been developed to explore improved linearity in the LLRF system. The linearizers operate at 476 MHz with 15 dB dynamic range and 1 MHz linear control bandwidth. Results from lab measurements and high current beam tests are presented. Future development plans, conclusions from beam testing and ideas for future use of this linearization technique are presented.

  10. Controllability Analysis for Operation Margin of Zone 3 Impedance Relay

    Science.gov (United States)

    Li, Shenghu; Yorino, Naoto; Zoka, Yoshifumi

    Undesirable operation of zone 3 impedance relay (mho relays) is a possible factor for causing cascading failure as seen in several previous large scale blackouts, where power flow redistribution and power swing caused by outage or switching operations satisfy the condition for the relay operation. So far, the condition itself has not fully been investigated, and therefore, there has been little attempt to avoid the relay operation by means of direct power flow control. This paper analyzes the condition for zone 3 relay operation from the viewpoint of its sensitivity to power flow. An operating margin for security is defined for each relay to carry out effective monitoring. It is newly pointed out that undesirable operation can be effectively avoided by reactive power controls as well as real power controls. The method to compute the operation margin is also given through the analysis of the optimal Var location to control the operation margin. Effectiveness of the proposed method is demonstrated using the IEEE test systems.

  11. An Islanding Microgrid Power Sharing Approach Using Enhanced Virtual Impedance Control Scheme

    DEFF Research Database (Denmark)

    He, Jinwei; Li, Yun Wei; Guerrero, Josep M.

    2013-01-01

    In order to address the load sharing problem in islanding microgrids, this paper proposes an enhanced distributed generation (DG) unit virtual impedance control approach. The proposed method can realize accurate regulation of DG unit equivalent impedance at both fundamental and selected harmonic...... and PCC harmonic voltage compensation are achieved without using any fundamental and harmonic components extractions. Experimental results from a scaled single-phase microgrid prototype are provided to validate the feasibility of the proposed virtual impedance control approach....

  12. Droop Control with an Adjustable Complex Virtual Impedance Loop based on Cloud Model Theory

    DEFF Research Database (Denmark)

    Li, Yan; Shuai, Zhikang; Xu, Qinming

    2016-01-01

    not only can avoid the active/reactive power coupling, but also it may reduce the output voltage drop of the PCC voltage. The proposed adjustable complex virtual impedance loop is putted into the conventional P/Q droop control to overcome the difficulty of getting the line impedance, which may change...... sometimes. The cloud model theory is applied to get online the changing line impedance value, which relies on the relevance of the reactive power responding the changing line impedance. The verification of the proposed control strategy is done according to the simulation in a low voltage microgrid in Matlab....

  13. A digital controlled PV-inverter with grid impedance estimation for ENS detection

    DEFF Research Database (Denmark)

    Asiminoaei, Lucian; Teodorescu, Remus; Blaabjerg, Frede

    2005-01-01

    of a PV-inverter with different advanced, robust control strategies and an embedded online technique to determine the utility grid impedance. By injecting an interharmonic current and measuring the voltage response it is possible to estimate the grid impedance at the fundamental frequency. The presented...... technique, which is implemented with the existing sensors and the CPU of the PV-inverter, provides a fast and low cost approach for online impedance measurement, which may be used for detection of islanding operation. Practical tests on an existing PV-inverter validate the control methods, the impedance...... measurement, and the islanding detection....

  14. Road Impedance Model Study under the Control of Intersection Signal

    Directory of Open Access Journals (Sweden)

    Yunlin Luo

    2015-01-01

    Full Text Available Road traffic impedance model is a difficult and critical point in urban traffic assignment and route guidance. The paper takes a signalized intersection as the research object. On the basis of traditional traffic wave theory including the implementation of traffic wave model and the analysis of vehicles’ gathering and dissipating, the road traffic impedance model is researched by determining the basic travel time and waiting delay time. Numerical example results have proved that the proposed model in this paper has received better calculation performance compared to existing model, especially in flat hours. The values of mean absolute percentage error (MAPE and mean absolute deviation (MAD are separately reduced by 3.78% and 2.62 s. It shows that the proposed model has feasibility and availability in road traffic impedance under intersection signal.

  15. Impedance Control and Its Relation to Precision in Orofacial Movement

    Science.gov (United States)

    Laboissière, Rafael; Lametti, Daniel R.; Ostry, David J.

    2009-01-01

    Speech production involves some of the most precise and finely timed patterns of human movement. Here, in the context of jaw movement in speech, we show that spatial precision in speech production is systematically associated with the regulation of impedance and in particular, with jaw stiffness—a measure of resistance to displacement. We estimated stiffness and also variability during movement using a robotic device to apply brief force pulses to the jaw. Estimates of stiffness were obtained using the perturbed position and force trajectory and an estimate of what the trajectory would be in the absence of load. We estimated this “reference trajectory” using a new technique based on Fourier analysis. A moving-average (MA) procedure was used to estimate stiffness by modeling restoring force as the moving average of previous jaw displacements. The stiffness matrix was obtained from the steady state of the MA model. We applied this technique to data from 31 subjects whose jaw movements were perturbed during speech utterances and kinematically matched nonspeech movements. We observed systematic differences in stiffness over the course of jaw-lowering and jaw-raising movements that were correlated with measures of kinematic variability. Jaw stiffness was high and variability was low early and late in the movement when the jaw was elevated. Stiffness was low and variability was high in the middle of movement when the jaw was lowered. Similar patterns were observed for speech and nonspeech conditions. The systematic relationship between stiffness and variability points to the idea that stiffness regulation is integral to the control of orofacial movement variability. PMID:19420122

  16. Robot impedance control and passivity analysis with inner torque and velocity feedback loops

    Institute of Scientific and Technical Information of China (English)

    Michele FOCCHI; Gustavo A MEDRANO-CERDA; Thiago BOAVENTURA; Marco FRIGERIO; Claudio SEMINI; Jonas BUCHLI; Darwin G CALDWELL

    2016-01-01

    Impedance control is a well-established technique to control interaction forces in robotics. However, real implementations of impedance control with an inner loop may suffer from several limitations. In particular, the viable range of stable stiffness and damping values can be strongly affected by the bandwidth of the inner control loops (e.g., a torque loop) as well as by the filtering and sampling frequency. This paper provides an extensive analysis on how these aspects influence the stability region of impedance parameters as well as the passivity of the system. This will be supported by both simulations and experimental data. Moreover, a methodology for designing joint impedance controllers based on an inner torque loop and a positive velocity feedback loop will be presented. The goal of the velocity feedback is to increase (given the constraints to preserve stability) the bandwidth of the torque loop without the need of a complex controller.

  17. Fuzzy variable impedance control based on stiffness identification for human-robot cooperation

    Science.gov (United States)

    Mao, Dachao; Yang, Wenlong; Du, Zhijiang

    2017-06-01

    This paper presents a dynamic fuzzy variable impedance control algorithm for human-robot cooperation. In order to estimate the intention of human for co-manipulation, a fuzzy inference system is set up to adjust the impedance parameter. Aiming at regulating the output fuzzy universe based on the human arm’s stiffness, an online stiffness identification method is developed. A drag interaction task is conducted on a 5-DOF robot with variable impedance control. Experimental results demonstrate that the proposed algorithm is superior.

  18. Control of the Radiation Patterns Using Homogeneous and Isotropic Impedance Metasurface

    Directory of Open Access Journals (Sweden)

    Fan Yang

    2015-01-01

    Full Text Available We propose to control the radiation patterns of a two-dimensional (2D point source by using impedance metasurfaces. We show that the radiation patterns can be manipulated by altering the surface impedance of the metasurface. Full-wave simulation results are provided to validate the theoretical derivations. The proposed design enjoys novel properties of isotropy, homogeneity, low profile, and high selectivity of frequency, making it potentially applicable in many applications. We also point out that this design can be implemented with active metasurfaces and the surface impedance can be tuned by modulating the value of loaded elements, like resistors, inductors, and capacitors.

  19. Manufacturing and the LLRF Tests of the SANAEM RFQ

    CERN Document Server

    Turemen, G; Akgun, Y; Bolukdemir, S; Kilic, I; Yasatekin, B; Yildiz, H; Unel, G

    2016-01-01

    The Turkish Atomic Energy Authority has been working on building an experimental proton beamline using local resources at the Saraykoy Nuclear Research and Training Center (SANAEM). The radio frequency quadrupole (RFQ) was manufactured after the completion of beam dynamics and 3D electromagnetic simulation studies. The vanes were machined using a three axis CNC machine. A CMM was used for both the acceptance tests of the vanes and their assembly. Production and assembly errors were found acceptable for this cavity, the very first one developed in Turkey. The aluminum vanes were copper coated by electroplating. The coated vanes were bolted and bonded with eight screws, eight pins and two different adhesives. A silver paste was used for RF sealing and a low vapor pressure epoxy was used for vacuum isolation. First LLRF tests of the RFQ were performed using the phase shift method with a bead-pull setup, a VNA, an N-type RF coupler and a pick-up loop. Cavity quality factor was measured with 3dB method for differe...

  20. LLRF design for the HINS-SRF test facility at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Branlanrd, J.; Chase, B.; Cullerton, E.; Joireman, P.; Tupikov, V.; /Fermilab

    2010-09-01

    The High Intensity Neutrino Source (HINS) R&D program requires super conducting single spoke resonators operating at 325 MHz (SSR1). After coupler installation, these cavities are tested at the HINS-SRF facility at Fermilab. The LLRF requirements for these tests include support for continuous wave and pulsed mode operations, with the ability to track the resonance frequency of the tested cavity. Real-time measurement of the cavity loaded Q and Q{sub 0} are implemented using gradient decay techniques, allowing for Q{sub 0} versus E{sub acc} plots. A real time cavity simulator was also developed to test the LLRF system and verify its functionality.

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

    Science.gov (United States)

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

    2013-01-01

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

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

    Science.gov (United States)

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

    2013-01-01

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

  3. Label-free hybridoma cell culture quality control by a chip-based impedance flow cytometer.

    Science.gov (United States)

    Pierzchalski, Arkadiusz; Hebeisen, Monika; Mittag, Anja; Bocsi, Jozsef; Di Berardino, Marco; Tarnok, Attila

    2012-11-07

    Impedance flow cytometry (IFC) was evaluated as a possible alternative to fluorescence-based methods for on-line quality monitoring of hybridoma cells. Hybridoma cells were cultured at different cell densities and viability was estimated by means of IFC and fluorescence-based flow cytometry (FCM). Cell death was determined by measuring the impedance phase value at high frequency in low conductivity buffer. IFC data correlate well with reference FCM measurements using AnnexinV and 7-AAD staining. Hybridoma cells growing at different densities in cell culture revealed a density-dependent subpopulation pattern. Living cells of high density cultures show reduced impedance amplitudes, indicating particular cellular changes. Dead cell subpopulations become evident in cultures with increasing cell densities. In addition, a novel intermediate subpopulation, which most probably represents apoptotic cells, was identified. These results emphasize the extraordinary sensitivity of high frequency impedance measurements and their suitability for hybridoma cell culture quality control.

  4. Duct wall impedance control as an advanced concept for acoustic suppression enhancement. [engine noise reduction

    Science.gov (United States)

    Dean, P. D.

    1978-01-01

    A systems concept procedure is described for the optimization of acoustic duct liner design for both uniform and multisegment types. The concept was implemented by the use of a double reverberant chamber flow duct facility coupled with sophisticated computer control and acoustic analysis systems. The optimization procedure for liner insertion loss was based on the concept of variable liner impedance produced by bias air flow through a multilayer, resonant cavity liner. A multiple microphone technique for in situ wall impedance measurements was used and successfully adapted to produce automated measurements for all liner configurations tested. The complete validation of the systems concept was prevented by the inability to optimize the insertion loss using bias flow induced wall impedance changes. This inability appeared to be a direct function of the presence of a higher order energy carrying modes which were not influenced significantly by the wall impedance changes.

  5. Studying the implementation of iterative impedance control for assistive hand rehabilitation using an exoskeleton.

    Science.gov (United States)

    Martineau, T; Vaidyanathan, R

    2017-07-01

    A positive training synergy can be obtained when two individuals attempt to learn the same motor task while mechanically coupled to one another. In this paper, we have studied how mimicking this interaction through impedance control can be exploited to improve assistance delivered by hand exoskeleton devices during rehabilitation. In this context, the machine and user take complementary roles akin to two coupled individuals. We present the derivation of a dynamic model of the human hand for the purpose of controller development for new hand exoskeleton platforms. Using this model, we have simulated the behavior of an iterative impedance controller programmed for rehabilitative training. The controller interacts with cylindrical objects to be grasped by means of an inverse kinematic mapping and tuning of mechanical impedance characteristic of the finger joints. Through fusion of concepts from motor control theory, muscle impedance and task oriented control, the controller is capable of iteratively learn to accomplish simple tasks involving grasping and lifting while cooperating with a user. The controller is also capable of adapting to more complex dynamics for more dexterous tasks, such as pulling on a hand-bar or loosening the cap of a jar. We believe the human-robot synergy established in this investigation has benefits to therapy. It can be combined with a broad range of training exercises and represents an incremental step towards mimicking natural human motor responses.

  6. Impedance Coordinative Control for Cascaded Converter in Bidirectional Application

    DEFF Research Database (Denmark)

    Tian, Yanjun; Deng, Fujin; Chen, Zhe;

    2015-01-01

    difference between forward and reversed power flow. This paper addresses the analysis with the topology of cascaded dual-active-bridge converter (DAB) with inverter, and the proposed control method can also be implemented in unidirectional applications and other general cascaded converter system...

  7. Power flow analysis for droop controlled LV hybrid AC-DC microgrids with virtual impedance

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Vasquez, Juan Carlos

    2014-01-01

    The AC-DC hybrid microgrid is an effective form of utilizing different energy resources and the analysis of this system requires a proper power flow algorithm. This paper proposes a suitable power flow algorithm for LV hybrid AC-DC microgrid based on droop control and virtual impedance. Droop...... and virtual impedance concepts for AC network, DC network and interlinking converter are reviewed so as to model it in the power flow analysis. The validation of the algorithm is verified by comparing it with steady state results from detailed time domain simulation. The effectiveness of the proposed...

  8. Peg-in-Hole assembly using Impedance Control with a 6 DOF Robot

    NARCIS (Netherlands)

    Broenink, Jan F.; Tiernego, Martin L.J.; Bruzzone, Augostino G.; Kerckhoffs, Eugene J.H.

    1996-01-01

    To gain insight in problems of industrial assembly operations, an anthropomorphic robot equipped with a vision system was used to insert differently shaped pegs into corresponding holes of a plastic ball. Spatial impedance control was used, to properly deal with the interaction between robot and env

  9. Impedance measurements on Au microelectrodes using controlled atmosphere high temperature scanning probe microscope

    DEFF Research Database (Denmark)

    Wu, Yuehua; Hansen, Karin Vels; Jacobsen, Torben

    2011-01-01

    High temperature impedance measurements on Au microelectrodes deposited on polished yttria stabilized zirconia (YSZ) pellets were demonstrated using a newly designed controlled atmosphere high temperature scanning probe microscope (CAHT-SPM). Probes based on Pt0.8Ir0.2 were fabricated and employed...... in all the investigations. The electrical properties of the Au microelectrodes were investigated using CAHT-SPM at various temperatures in air. The influences of the tip-sample force and of the size of the microelectrode on the electrical properties of the Au microelectrodes were also studied....... The impedance spectra of circular Au microelectrodes down to 8μm in diameter at different temperatures were successfully obtained. The CAHT-SPM presented in this paper is capable of obtaining topography images, conductivity images and impedance spectra in-situ in a temperature range from room temperature...

  10. Fuzzy force control of constrained robot manipulators based on impedance model in an unknown environment

    Institute of Scientific and Technical Information of China (English)

    LIU Hongyi; WANG Lei; WANG Fei

    2007-01-01

    To precisely implement the force control of robot manipulators in an unknown environment,a control strategy based on fuzzy prediction of the reference trajectory in the impedance model is developed.The force tracking experiments are executed in an open-architecture control system with different tracking velocities,different desired forces,different contact stiffnesses and different surface figurations.The corresponding force control results are compared and analyzed.The influences of unknown parameters of the environment on the contact force are analyzed based on experimental data,and the tunings of predictive scale factors are illustrated.The experimental results show that the desired trajectory in the impedance model is predicted exactly and rapidly in the cases that the contact surface is unknown,the contact stiffness changes,and the fuzzy force control algorithm has high adaptability to the unknown environment.

  11. Workspace Safe Operation of a Force- or Impedance-Controlled Robot

    Science.gov (United States)

    Abdallah, Muhammad E. (Inventor); Hargrave, Brian (Inventor); Yamokoski, John D. (Inventor); Strawser, Philip A. (Inventor)

    2013-01-01

    A method of controlling a robotic manipulator of a force- or impedance-controlled robot within an unstructured workspace includes imposing a saturation limit on a static force applied by the manipulator to its surrounding environment, and may include determining a contact force between the manipulator and an object in the unstructured workspace, and executing a dynamic reflex when the contact force exceeds a threshold to thereby alleviate an inertial impulse not addressed by the saturation limited static force. The method may include calculating a required reflex torque to be imparted by a joint actuator to a robotic joint. A robotic system includes a robotic manipulator having an unstructured workspace and a controller that is electrically connected to the manipulator, and which controls the manipulator using force- or impedance-based commands. The controller, which is also disclosed herein, automatically imposes the saturation limit and may execute the dynamic reflex noted above.

  12. Adaptive impedance control of a hydraulic suspension system using particle swarm optimisation

    Science.gov (United States)

    Fateh, Mohammad Mehdi; Moradi Zirkohi, Majid

    2011-12-01

    This paper presents a novel active control approach for a hydraulic suspension system subject to road disturbances. A novel impedance model is used as a model reference in a particular robust adaptive control which is applied for the first time to the hydraulic suspension system. A scheme is introduced for selecting the impedance parameters. The impedance model prescribes a desired behaviour of the active suspension system in a wide range of different road conditions. Moreover, performance of the control system is improved by applying a particle swarm optimisation algorithm for optimising control design parameters. Design of the control system consists of two interior loops. The inner loop is a force control of the hydraulic actuator, while the outer loop is a robust model reference adaptive control (MRAC). This type of MRAC has been applied for uncertain linear systems. As another novelty, despite nonlinearity of the hydraulic actuator, the suspension system and the force loop together are presented as an uncertain linear system to the MRAC. The proposed control method is simulated on a quarter-car model. Simulation results show effectiveness of the method.

  13. Limb dominance results from asymmetries in predictive and impedance control mechanisms.

    Directory of Open Access Journals (Sweden)

    Vivek Yadav

    Full Text Available Handedness is a pronounced feature of human motor behavior, yet the underlying neural mechanisms remain unclear. We hypothesize that motor lateralization results from asymmetries in predictive control of task dynamics and in control of limb impedance. To test this hypothesis, we present an experiment with two different force field environments, a field with a predictable magnitude that varies with the square of velocity, and a field with a less predictable magnitude that varies linearly with velocity. These fields were designed to be compatible with controllers that are specialized in predicting limb and task dynamics, and modulating position and velocity dependent impedance, respectively. Because the velocity square field does not change the form of the equations of motion for the reaching arm, we reasoned that a forward dynamic-type controller should perform well in this field, while control of linear damping and stiffness terms should be less effective. In contrast, the unpredictable linear field should be most compatible with impedance control, but incompatible with predictive dynamics control. We measured steady state final position accuracy and 3 trajectory features during exposure to these fields: Mean squared jerk, Straightness, and Movement time. Our results confirmed that each arm made straighter, smoother, and quicker movements in its compatible field. Both arms showed similar final position accuracies, which were achieved using more extensive corrective sub-movements when either arm performed in its incompatible field. Finally, each arm showed limited adaptation to its incompatible field. Analysis of the dependence of trajectory errors on field magnitude suggested that dominant arm adaptation occurred by prediction of the mean field, thus exploiting predictive mechanisms for adaptation to the unpredictable field. Overall, our results support the hypothesis that motor lateralization reflects asymmetries in specific motor control

  14. Design of an expert system to automatically calibrate impedance control for powered knee prostheses.

    Science.gov (United States)

    Wang, Ding; Liu, Ming; Zhang, Fan; Huang, He

    2013-06-01

    Many currently available powered knee prostheses (PKP) use finite state impedance control to operate a prosthetic knee joint. The desired impedance values were usually manually calibrated with trial-and-error in order to enable near-normal walking pattern. However, such a manual approach is inaccurate, time consuming, and impractical. This paper aimed to design an expert system that can tune the control impedance for powered knee prostheses automatically and quickly. The expert system was designed based on fuzzy logic inference (FLI) to match the desired knee motion and gait timing while walking. The developed system was validated on an able-bodied subject wearing a powered prosthesis. Preliminary experimental results demonstrated that the developed expert system can converge the user's knee profile and gait timing to the desired values within 2 minutes. Additionally, after the auto-tuning procedure, the user produced more symmetrical gait. These preliminary results indicate the promise of the designed expert system for quick and accuracy impedance calibration, which can significantly improve the practical value of powered lower limb prosthesis. Continuous engineering efforts are still needed to determine the calibration objectives and validate the expert system.

  15. Model reference adaptive impedance control for physical human-robot interaction

    Institute of Scientific and Technical Information of China (English)

    Bakur ALQAUDI; Hamidreza MODARES; Isura RANATUNGA; Shaikh M TOUSIF; Frank L LEWIS; Dan O POPA

    2016-01-01

    This paper presents a novel enhanced human-robot interaction system based on model reference adaptive control. The presented method delivers guaranteed stability and task performance and has two control loops. A robot-specific inner loop, which is a neuroadaptive controller, learns the robot dynamics online and makes the robot respond like a prescribed impedance model. This loop uses no task information, including no prescribed trajectory. A task-specific outer loop takes into account the human operator dynamics and adapts the prescribed robot impedance model so that the combined human-robot system has desirable characteristics for task performance. This design is based on model reference adaptive control, but of a nonstandard form. The net result is a controller with both adaptive impedance characteristics and assistive inputs that augment the human operator to provide improved task performance of the human-robot team. Simulations verify the performance of the proposed controller in a repetitive point-to-point motion task. Actual experimental implementations on a PR2 robot further corroborate the effectiveness of the approach.

  16. Impedance Control with Variable Damping for Bilateral Teleoperation under Time Delay

    Science.gov (United States)

    Cho, Hyun Chul; Park, Jong Hyeon

    This paper proposes a new impedance controller that is to be applied to bilateral teleoperation under a time delay. The controller has a variable damping designed to achieve a good tacking performance and contact stability concurrently. The damping of the slave impedance is modulated based on the distance between the slave and its environment. The stability of the teleoperation system including the human operator and the environment is analyzed using the absolute stability. The validity of the proposed control scheme is demonstrated in experiments with a 1-DOF teleoperation system. The experimental results show that the system performs better with a damping modulation than with a constant damping or with a variable damping, which changes based on contact signals.

  17. Plasmonic Mode Converter for Controlling Optical Impedance and Nanoscale Light-matter Interaction

    CERN Document Server

    Hung, Yun-Ting; Huang, Jer-Shing

    2012-01-01

    Nanoantennas and plasmonic waveguides can concentrate and manipulate light in a sub-wavelength area. To ensure strong interaction between light and nanomatter, it is of key importance to control the spatial distribution and polarization of the guided modes such that the optical impedance matches to that of nearby quantum systems. Nanosized plasmonic two-wire transmission lines consisting of two parallel plasmonic nanowires separated by a nanogap provide unique opportunity to achieve the required control. According to the symmetry of the charge distribution, the guided transverse electric and transverse magnetic modes on a two-wire transmission line exhibit distinct propagation properties and optical impedance that are suitable for various different circuit functions. In this work, we present efficient mode converters for the control of guided modes in a plasmonic nanocircuit. The mode conversion is achieved through varying the path length, wire cross section and the surrounding index of refraction. We demonst...

  18. LLRF05 : Workshop on Low Level RF, CERN. 10-13 October 2005

    CERN Multimedia

    2005-01-01

    Sophisticated Low Level RF systems are needed in modern particle accelerators to deal with the characteristics of state-of-the-art RF accelerating structures and their power sources, and to meet unprecedented levels of performance. The goal of the LLRF05 workshop is to share experience between linac and synchrotron projects (SNS, J-PARC, ILC, LHC etc.) and to discuss the best engineering practice.

  19. Participants of the LLRF05 : Workshop on Low Level RF, CERN 10-13 October 2005

    CERN Multimedia

    Maximilien Brice

    2005-01-01

    Sophisticated Low Level RF systems are needed in modern particle accelerators to deal with the characteristics of state-of-the-art RF accelerating structures and their power sources, and to meet unprecedented levels of performance. The goal of the LLRF05 workshop is to share experience between linac and synchrotron projects (SNS, J-PARC, ILC, LHC etc.) and to discuss the best engineering practice.

  20. Impedance Control and its Effects on a Humanoid Robot Playing Table Tennis

    Directory of Open Access Journals (Sweden)

    Rong Xiong

    2012-11-01

    Full Text Available This paper proposes an impedance control scheme used on humanoid robots for stability maintenance when the robot is expected to carry out fast manipulatory tasks. We take table tennis playing as an example to study this issue. The fast acceleration required by table tennis rallying will result in an unknown large reaction force on the robot, causing the body to swing back and forth in an oscillating motion and the foot to lose complete contact with the ground. To improve the stability during fast manipulation and in order to resist disturbances due to the reaction force, we introduce impedance control to absorb the impact and decrease the amplitude of body swinging. The system’s adjusting time is also reduced and the oscillations are eliminated according to the experimental results, which show the effectiveness of our scheme.

  1. An improved design of virtual output impedance loop for droop-controlled parallel three-phase Voltage Source Inverters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Blaabjerg, Frede; Chen, Zhe

    2012-01-01

    The virtual output impedance loop is known as an effective way to enhance the load sharing stability and quality of droop-controlled parallel inverters. This paper proposes an improved design of virtual output impedance loop for parallel three-phase voltage source inverters. In the approach, a vi...

  2. Adaptive Impedance Control to Enhance Human Skill on a Haptic Interface System

    Directory of Open Access Journals (Sweden)

    Satoshi Suzuki

    2012-01-01

    Full Text Available Adaptive assistive control for a haptic interface system is proposed in the present paper. The assistive control system consists of three subsystems: a servo controller to match the response of the controlled machine to the virtual model, an online identifier of the operator’s control characteristics, and a variable dynamics control using adaptive mechanism. The adaptive mechanism tunes an impedance of the virtual model for the haptic device according to the identified operator’s characteristics so as to enhance the operator’s control performance. The adaptive law is derived by utilizing a Lyapunov candidate function. Using a haptic interface device composed by a xy-stage, an effectiveness of the proposed control method was evaluated experimentally. As a result, it was confirmed that the operator’s characteristics can be estimated sufficiently and that performance of the operation was enhanced by the variable dynamics assistive control.

  3. Skin-impedance in Fabry Disease: A prospective, controlled, non-randomized clinical study

    Directory of Open Access Journals (Sweden)

    Lidicker Jeffrey R

    2008-11-01

    Full Text Available Abstract Background We previously demonstrated improved sweating after enzyme replacement therapy (ERT in Fabry disease using the thermo-regularity sweat and quantitative sudomotor axon reflex tests. Skin-impedance, a measure skin-moisture (sweating, has been used in the clinical evaluation of burns and pressure ulcers using the portable dynamic dermal impedance monitor (DDIM system. Methods We compared skin impedance measurements in hemizygous patients with Fabry disease (22 post 3-years of bi-weekly ERT and 5 ERT naive and 22 healthy controls. Force compensated skin-moisture values were used for statistical analysis. Outcome measures included 1 moisture reading of the 100th repetitive reading, 2 rate of change, 3 average of 60–110th reading and 4 overall average of all readings. Results All outcome measures showed a significant difference in skin-moisture between Fabry patients and control subjects (p Conclusion The instrument portability, ease of its use, a relatively short time required for the assessment, and the fact that DDIM system was able to detect the difference in skin-moisture renders the instrument a useful clinical tool.

  4. Adaptive control of a variable-impedance ankle-foot orthosis to assist drop-foot gait.

    Science.gov (United States)

    Blaya, Joaquin A; Herr, Hugh

    2004-03-01

    An active ankle-foot orthoses (AAFO) is presented where the impedance of the orthotic joint is modulated throughout the walking cycle to treat drop-foot gait. During controlled plantar flexion, a biomimetic torsional spring control is applied where orthotic joint stiffness is actively adjusted to minimize forefoot collisions with the ground. Throughout late stance, joint impedance is minimized so as not to impede powered plantar flexion movements, and during the swing phase, a torsional spring-damper control lifts the foot to provide toe clearance. To assess the clinical effects of variable-impedance control, kinetic and kinematic gait data were collected on two drop-foot participants wearing the AAFO. For each participant, zero, constant, and variable impedance control strategies were evaluated and the results were compared to the mechanics of three age, weight, and height matched normals. We find that actively adjusting joint impedance reduces the occurrence of slap foot allows greater powered plantar flexion and provides for less kinematic difference during swing when compared to normals. These results indicate that a variable-impedance orthosis may have certain clinical benefits for the treatment of drop-foot gait compared to conventional ankle-foot orthoses having zero or constant stiffness joint behaviors.

  5. A force commanded impedance control for a robot finger with uncertain kinematics

    Energy Technology Data Exchange (ETDEWEB)

    Doulgeri, Z.; Arimoto, Suguru

    1999-10-01

    The authors consider the problem of impedance control for the physical interaction between the soft tip of a robot finger, where the nonlinear characteristics of the reproducing force and the finger dynamic parameters are unknown, and a rigid object or environment under kinematic uncertainties arising from both uncertain contact point location and uncertain rigid object geometry. An adaptive controller is proposed, and the asymptotic stability of the force regulation problem is shown for the planar case even when finger kinematics and rigid surface orientation are uncertain. Confirmation of the theoretical findings is done through simulation of a 3-degree-of-freedom planar robotic finger.

  6. Evaluation of impedance on biological Tissues using automatic control measurement system

    Energy Technology Data Exchange (ETDEWEB)

    Kil, Sang Hyeong; Shin, Dong Hoon; Lee, Seong Mo [Pusan National University, Yangsan (Korea, Republic of); Lee, Moo Seok; Kim, Sang Sik [Pusan National University, Busan (Korea, Republic of); Kim, Gun FDo; Lee, Jong Kyu [Pukyung National University, Busan (Korea, Republic of)

    2015-08-15

    Each biological tissue has endemic electrical characteristics owing to various differences such as those in cellular arrangement or organization form. The endemic electrical characteristics change when any biological change occurs. This work is a preliminary study surveying the changes in the electrical characteristics of biological tissue caused by radiation exposure. For protection against radiation hazards, therefore the electrical characteristics of living tissue were evaluated after development of the automatic control measurement system using LabVIEW. No alteration of biological tissues was observed before and after measurement of the electrical characteristics, and the biological tissues exhibited similar patterns. Through repeated measurements using the impedance/gain-phase analyzer, the coefficient of variation was determined as within 10%. The reproducibility impedance phase difference in electrical characteristics of the biological tissue did not change, and the tissue had resistance. The absolute value of impedance decreased constantly in proportion to the frequency. It has become possible to understand the electrical characteristics of biological tissues through the measurements made possible by the use of the developed.

  7. Modified impedance control for robotic saw cutting: Simulation and implementation in three degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Kriikku, E.M. [Westinghouse Savannah River Co., Aiken, SC (United States); Reynolds, D.L.; Carroll, J.J.; Dawson, D.M. [Clemson Univ., SC (United States). School of Electrical and Computer Engineering

    1993-12-31

    The Savannah River Site (SRS) production and decommissioning operations produce solid radioactive transuranic (TRU) waste. This waste must be repackaged and sent to the Waste Isolation Pilot Plant (WIPP) for permanent disposal. The Savannah River Technology Center (SRTC) built a test facility to demonstrate simulated waste processing. The test facility use`s a CIMCORP multi-axis robot system, a CIMROC{trademark} II robot controller, and an electric circular saw to remotely open and size reduce plywood crates. The robot can either be teleoperated using joysticks or autonomously controlled via the, CIMROC{trademark} II. Both methods are inadequate for circular saw cutting of plywood crates due to frequent saw blade binding. Blade binding results from the current commercial robot controller limitations. The limitations are overcome by incorporating additional sensor information into the existing controller structure. In this paper we utilize a force sensor and a frequency counter to implement a modified impedance controller which prevents saw blade binding.

  8. Modified impedance control for robotic saw cutting: Simulation and implementation in three degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Kriikku, E.M. (Westinghouse Savannah River Co., Aiken, SC (United States)); Reynolds, D.L.; Carroll, J.J.; Dawson, D.M. (Clemson Univ., SC (United States). School of Electrical and Computer Engineering)

    1993-01-01

    The Savannah River Site (SRS) production and decommissioning operations produce solid radioactive transuranic (TRU) waste. This waste must be repackaged and sent to the Waste Isolation Pilot Plant (WIPP) for permanent disposal. The Savannah River Technology Center (SRTC) built a test facility to demonstrate simulated waste processing. The test facility use's a CIMCORP multi-axis robot system, a CIMROC[trademark] II robot controller, and an electric circular saw to remotely open and size reduce plywood crates. The robot can either be teleoperated using joysticks or autonomously controlled via the, CIMROC[trademark] II. Both methods are inadequate for circular saw cutting of plywood crates due to frequent saw blade binding. Blade binding results from the current commercial robot controller limitations. The limitations are overcome by incorporating additional sensor information into the existing controller structure. In this paper we utilize a force sensor and a frequency counter to implement a modified impedance controller which prevents saw blade binding.

  9. Visualized Multiprobe Electrical Impedance Measurements with STM Tips Using Shear Force Feedback Control

    Directory of Open Access Journals (Sweden)

    Luis Botaya

    2016-05-01

    Full Text Available Here we devise a multiprobe electrical measurement system based on quartz tuning forks (QTFs and metallic tips capable of having full 3D control over the position of the probes. The system is based on the use of bent tungsten tips that are placed in mechanical contact (glue-free solution with a QTF sensor. Shear forces acting in the probe are measured to control the tip-sample distance in the Z direction. Moreover, the tilting of the tip allows the visualization of the experiment under the optical microscope, allowing the coordination of the probes in X and Y directions. Meanwhile, the metallic tips are connected to a current–voltage amplifier circuit to measure the currents and thus the impedance of the studied samples. We discuss here the different aspects that must be addressed when conducting these multiprobe experiments, such as the amplitude of oscillation, shear force distance control, and wire tilting. Different results obtained in the measurement of calibration samples and microparticles are presented. They demonstrate the feasibility of the system to measure the impedance of the samples with a full 3D control on the position of the nanotips.

  10. Multiple impedance control of space free-flying robots via virtual linkages

    Science.gov (United States)

    Rastegari, Rambod; Moosavian, S. Ali A.

    2010-03-01

    Multiple impedance control (MIC) is a Model-Based algorithm that enforces a designated impedance on all cooperating manipulators, the manipulated object, and the moving base if applied on a mobile robotic system such as a space free flying robotic system. The MIC can be properly applied to manipulate a grasped object, and move it on a desired path. However, during such maneuvers, some inner forces and torques are usually produced in the object. For tuning the inner object forces, it is needed to model the inner forces/torques or their effects on the object. In this paper, a virtual linkage model is introduced to determine the inner forces using the MIC law. Also, the load distribution among the end-effectors is modeled. To this end, the MIC law is used to control both path tracking and inner forces tuning when manipulating an object. The moving object is grasped solidly with two 6 degrees of freedom (DOF) cooperating end-effectors mounted on a 6 DOF spacecraft appended with a 2 DOF antenna. An explicit dynamics model of this highly complicated 20 DOF system is derived using SPACEMAPLE, and then simulated in MATLAB. The obtained results reveal good tracking performance of the proposed MIC controller, besides tuning the object internal forces due to tension or compression forces, also torsion and bending moments.

  11. Development of Adaptive Acoustic Impedance Control Technologies of Acoustic Duct Liner

    Directory of Open Access Journals (Sweden)

    Hiroshi Kobayashi

    2011-01-01

    Full Text Available This paper describes the development of adaptive acoustic impedance control (AAC technologies to achieve a larger fan noise reduction, by adaptively adjusting reactance and resistance of the acoustic liner impedance. For the actual proof of the AAC technology III performance, the advanced fan noise absorption control duct liner II was made on trial basis, with the simple control system and the plain device. And, then, the duct liner II was examined for the AAC technology I, II, and III models, using the high speed fan test facility. The test results made clear that the duct liner II of the AAC technology III model could achieve the fan noise reduction higher than O.A. SPL 10 dB (A at the maximum fan speed 6000 rpm, containing the reduction of fundamental BPF tone of 18 dB and 2nd BPF tone of 10 dB in response to the fan peed change from 3000 to 6000 rpm.

  12. A high performance DAC /DDS daughter module for the RHIC LLRF platform

    Energy Technology Data Exchange (ETDEWEB)

    Hayes, T.; Harvey, M.; Narayan, G.; Severino, F.; Smith, K.S.; Yuan, S.

    2011-03-28

    The RHIC LLRF upgrade is a flexible, modular system. Output signals are generated by a custom designed XMC card with 4 high speed digital to analog (DAC) converters interfaced to a high performance field programmable gate array (FPGA). This paper discusses the hardware details of the XMC DAC board as well as the implementation of a low noise rf synthesizer with digital IQ modulation. This synthesizer also provides injection phase cogging and frequency hop rebucketing capabilities. A new modular RHIC LLRF system was recently designed and commissioned based on custom designed XMC cards. As part of that effort a high speed, four channel DAC board was designed. The board uses Maxim MAX5891 16 bit DACs with a maximum update rate of 600 Msps. Since this module is intended to be used for many different systems throughout the Collider Accelerator complex, it was designed to be as generic as possible. One major application of this DAC card is to implement digital synthesizers to provide drive signals to the various cavities at RHIC. Since RHIC is a storage ring with stores that typically last many hours, extremely low RF noise is a critical requirement. Synchrotron frequencies at RHIC range from a few hertz to several hundred hertz depending on the species and point in the acceleration cycle so close in phase noise is a major concern. The RHIC LLRF system uses the Update Link, a deterministic, high speed data link that broadcasts the revolution frequency and the synchronous phase angle. The digital synthesizers use this data to generate a properly phased analog drive signal. The synthesizers must also provide smooth phase shifts for cogging and support frequency shift rebucketing. One additional feature implemented in the FPGA is a digital waveform generator (WFG) that generates I and Q data pairs based on a user selected amplitude and phase profile as a function of time.

  13. Impedance control in a wave-based teleoperator for rehabilitation motor therapies assisted by robots.

    Science.gov (United States)

    Mendoza, Marco; Bonilla, Isela; González-Galván, Emilio; Reyes, Fernando

    2016-01-01

    This paper presents an improved wave-based bilateral teleoperation scheme for rehabilitation therapies assisted by robot manipulators. The main feature of this bilateral teleoperator is that both robot manipulators, master and slave, are controlled by impedance. Thus, a pair of motion-based adaptive impedance controllers are integrated into a wave-based configuration, in order to guarantee a stable human-robot interaction and to compensate the position drift, characteristic of the available schemes of bilateral teleoperation. Moreover, the teleoperator stability, in the presence of time delays in the communication channel, is guaranteed because the wave-variable approach is included to encode the force and velocity signals. It should be noted that the proposed structure enables the implementation of several teleoperator schemes, from passive therapies, without the intervention of a human operator on the master side, to fully active therapies where both manipulators interact with humans in a stable manner. The suitable performance of the proposed teleoperator is verified through some results obtained from the simulation of the passive and active-constrained modes, by considering typical tasks in motor-therapy rehabilitation, where an improved behavior is observed when compared to implementations of the classical wave-based approach.

  14. Performance Comparison for Virtual Impedance Techniques Used in Droop Controlled Islanded Microgrids

    DEFF Research Database (Denmark)

    Micallef, Alexander; Apap, Maurice; Spiteri-Staines, Cyril;

    2016-01-01

    of the current harmonics which can add to the voltage distortion at the PCC. This paper compares the performance of resistive, inductive, inductiveresistive and resistive-capacitive virtual impedance loops with respect to current sharing and voltage harmonic distortion at the PCC. Simulation results are given......). Virtual impedance loops were proposed in literature to improve the current sharing between the inverters by normalizing the output impedance of the inverters. However, virtual impedance loops have constraints in this respect since the improvement in the current sharing occurs through redistribution...... for a single phase microgrid setup to achieve a fair performance comparison of the different virtual impedance techniques....

  15. Controllable transmission and total reflection through an impedance-matched acoustic metasurface

    KAUST Repository

    Mei, Jun

    2014-12-02

    A general design paradigm for a novel type of acoustic metasurface is proposed by introducing periodically repeated supercells on a rigid thin plate, where each supercell contains multiple cut-through slits that are filled with materials possessing different refractive indices but the same impedance as that of the host medium. When the wavelength of the incident wave is smaller than the periodicity, the direction of the transmitted wave with nearly unity transmittance can be chosen by engineering the phase discontinuities along the transverse direction. When the wavelength is larger than the periodicity, even though the metasurface is impedance matched to the host medium, most of the incident energy is reflected back and the remaining portion is converted into a surface-bound mode. We show that both the transmitted wave control and the high reflection with the surface mode excitation can be interpreted by a unified analytic model based on mode-coupling theory. Our general design principle not only supplies the functionalities of reflection-type acoustic metasurfaces, but also exhibits unprecedented flexibility and efficiency in various domains of wave manipulation for possible applications in fields like refracting, collimating, focusing or absorbing wave energy.

  16. Semi-active control of piezoelectric coating's underwater sound absorption by combining design of the shunt impedances

    Science.gov (United States)

    Sun, Yang; Li, Zhaohui; Huang, Aigen; Li, Qihu

    2015-10-01

    Piezoelectric shunt damping technology has been applied in the field of underwater sound absorption in recent years. In order to achieve broadband echo reduction, semi-active control of sound absorption of multi-layered piezoelectric coating by shunt damping is significant. In this paper, a practical method is proposed to control the underwater sound absorption coefficients of piezoelectric coating layers by combining design of the shunt impedance that allows certain sound absorption coefficients at setting frequencies. A one-dimensional electro-acoustic model of the piezoelectric coating and the backing is established based on the Mason equivalent circuit theory. First, the shunt impedance of the coating is derived under the constraint of sound absorption coefficient at one frequency. Then, taking the 1-3 piezoelectric composite coating as an example, the sound absorption properties of the coating shunted to the designed shunt impedance are investigated. Next, on the basis of that, an iterative method for two constrained frequencies and an optimizing algorithm for multiple constrained frequencies are provided for combining design of the shunt impedances. At last, an experimental sample with four piezoelectric material layers is manufactured, of which the sound absorption coefficients are measured in an impedance tube. The experimental results show good agreement with the finite element simulation results. It is proved that a serial R-L circuit can control the peak frequency, maximum and bandwidth of the sound absorption coefficient and the combining R-L circuits shunted to multiple layers can control the sound absorption coefficients at multiple frequencies.

  17. A Cyber Expert System for Auto-Tuning Powered Prosthesis Impedance Control Parameters.

    Science.gov (United States)

    Huang, He; Crouch, Dustin L; Liu, Ming; Sawicki, Gregory S; Wang, Ding

    2016-05-01

    Typically impedance control parameters (e.g., stiffness and damping) in powered lower limb prostheses are fine-tuned by human experts (HMEs), which is time and resource intensive. Automated tuning procedures would make powered prostheses more practical for clinical use. In this study, we developed a novel cyber expert system (CES) that encoded HME tuning decisions as computer rules to auto-tune control parameters for a powered knee (passive ankle) prosthesis. The tuning performance of CES was preliminarily quantified on two able-bodied subjects and two transfemoral amputees. After CES and HME tuning, we observed normative prosthetic knee kinematics and improved or slightly improved gait symmetry and step width within each subject. Compared to HME, the CES tuning procedure required less time and no human intervention. Hence, using CES for auto-tuning prosthesis control was a sound concept, promising to enhance the practical value of powered prosthetic legs. However, the tuning goals of CES might not fully capture those of the HME. This was because we observed that HME tuning reduced trunk sway, while CES sometimes led to slightly increased trunk motion. Additional research is still needed to identify more appropriate tuning objectives for powered prosthetic legs to improve amputees' walking function.

  18. 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

    adequate power flow studies. In this paper, power flow analyses for both AC and DC microgrids are formulated and implemented. The mathematical models for both types of microgrids considering the concept of virtual impedance are used to be in conformity with the practical control of the distributed...... generators. As a result, calculation accuracy is improved for both AC and DC microgrid 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...

  19. Robust Impedance Control-based Lyapunov-Hamiltonian Approach for Constrained Robots

    Directory of Open Access Journals (Sweden)

    Haifa Mehdi

    2015-12-01

    Full Text Available A new design of a robust impedance controller for constrained robotic manipulators is presented. The main objective is to stabilize asymptotically, in the task space, the robotic manipulator's end effectors into a desired position, via a desired contact force under model uncertainties and measurement noise. In this work, the proposed approach is enough straightforward for application without force and position control separation. Robust asymptotic stability in the approach is proved using a Hamiltonian-Lyapunov approach. Besides this, a state/parameter observer and an acceleration estimator are proposed to handle the problems of force estimation, disturbance rejection and acceleration measurement. To ensure high performance, a Particle Swarm Optimization (PSO algorithm is used finally as an efficient and fast method for the offline fine-tuning of the controller’s parameters. In designing the PSO method, the Mean of Root Squared Error (MRSE is considered as a cost function in the Cartesian space. Finally, the example of the ABB-IRB 140 industrial robot with 6DOFs is used to validate the performances of the proposed approach.

  20. A Novel Grid Impedance Estimation Technique based on Adaptive Virtual Resistance Control Loop Applied to Distributed Generation Inverters

    DEFF Research Database (Denmark)

    Ghzaiel, Walid; Jebali-Ben Ghorbal, Manel; Slama-Belkhodja, Ilhem;

    2013-01-01

    The penetration of the distributed power generation systems (DPGSs) based on renewable sources (PV, WT) is strongly dependent on the quality of the power injected to the utility grid. However, the grid impedance variation, mainly caused by grid faults somewhere in the electric network, can degrade...... the power quality and even damage some sensitive loads connected at the point of the common coupling (PCC). This paper presents detection-estimation method of the grid impedance variation. This estimation tehnique aims to improve the dynamic of the distributed generation (DG) interfacing inverter control...... and to take the decision of either keep the DG connected, or disconnect it from the utility grid. The proposed method is based on a fast and easy grid fault detection method. A virtual damping resistance is used to drive the system to the resonance in order to extract the grid impedance parameters, both...

  1. A control approach for the operation of DG units under variations of interfacing impedance in grid-connected mode

    DEFF Research Database (Denmark)

    Hoseini, S. Kazem; Pouresmaeil, E.; Hosseinnia, S. H.

    2016-01-01

    converter is highly sensitive to the impacts of this impedance changes; then, DG unit cannot inject appropriate currents. To deal with the instability problem, a control method based on fractional order active sliding mode is proposed in this paper, which is less sensitive to variations of interfacing...... impedance. A fractional sliding surface, which demonstrates the desired dynamics of system is developed and then, the controller is designed in two phases as sliding and reaching phases to keep the control loop stable. Stability issues of the control method are discussed in details and the conditions...... in which the proposed model works in a stable operating mode is defined. The proposed control method takes a role to provide high quality power injection and ensures precise references tracking and fast response despite such uncertainties. Theoretical analyses and simulation results are established...

  2. An impedance grasping strategy

    NARCIS (Netherlands)

    Muñoz Arias, Mauricio; Scherpen, Jacqueline M.A.; Macchelli, Alessandro

    2014-01-01

    This work is devoted to an impedance grasping strategy for a class of standard mechanical systems in the port- Hamiltonian framework. The presented control strategy re- quires a set of coordinate transformations, since the impedance control in the port-Hamiltonian framework with structure preservati

  3. Pengembangan Bioelectrical Impedance Sebagai Control Commands Pengaturan Kecepatan Gerak Kursi Roda Dengan Metoda PID Controller

    Directory of Open Access Journals (Sweden)

    Juli Sardi

    2014-09-01

    Full Text Available In the present study, bioimpedance signals of human body was utilized to control speed of a wheelchair movement. A bioimpedance is electrically passive part contained the body tissues. The research is one of alternative solutions for patients with paralysis of the upper and lower limb. Firstly, design of system of the research consisted of bioimpedance measuring instruments and a mechanical design of the wheelchair. Bioimpedance measurement was performed by injecting a sinusoidal current source of 0.5 mArms with a frequency of 50 kHz to muscle tissue (shoulder to obtain the output voltage in the range of 0-5 Vdc. With impulse and manual thresholding methods, the voltage signal was classified into several controls command to adjust the speed and direction of the wheelchair control based on PID Controller. The experimental result of the research was realization of bioimpedance signal that used as a reference to control the direction and speed of the wheelchair with a success rate of 86.7 %. A wheelchair velocity was classified into three types of motion, namely slow, medium and fast. Slow speed has a rated speed of 30 Cm/s, medium speed value speed of 40 Cm/s and fast speed value of 50 Cm/s. The wheelchair can also turn to the left and the right in accordance with the wishes of wheelchair user beside to moving forward.

  4. Quantitative control of neuron adhesion at a neural interface using a conducting polymer composite with low electrical impedance.

    Science.gov (United States)

    Kim, Sung Yeol; Kim, Kwang-Min; Hoffman-Kim, Diane; Song, Hyun-Kon; Palmore, G Tayhas R

    2011-01-01

    Tailoring cell response on an electrode surface is essential in the application of neural interfaces. In this paper, a method of controlling neuron adhesion on the surface of an electrode was demonstrated using a conducting polymer composite as an electrode coating. The electrodeposited coating was functionalized further with biomolecules-of-interest (BOI), with their surface concentration controlled via repetition of carbodiimide chemistry. The result was an electrode surface that promoted localized adhesion of primary neurons, the density of which could be controlled quantitatively via changes in the number of layers of BOI added. Important to neural interfaces, it was found that additional layers of BOI caused an insignificant increase in the electrical impedance, especially when compared to the large drop in impedance upon coating of the electrode with the conducting polymer composite.

  5. Method to measure autonomic control of cardiac function using time interval parameters from impedance cardiography

    NARCIS (Netherlands)

    Meijer, J.H.; Boesveldt, S.; Elbertse, E.; Berendse, H.W.

    2008-01-01

    The time difference between the electrocardiogram and impedance cardiogram can be considered as a measure for the time delay between the electrical and mechanical activities of the heart. This time interval, characterized by the pre-ejection period (PEP), is related to the sympathetic autonomous ner

  6. A 96 channel receiver for the ILCTA LLRF system at Fermilab

    Energy Technology Data Exchange (ETDEWEB)

    Mavric, Uros; Chase, Brian; Branlard, Julien; Cullerton, Ed; Klepec, Dan; /Fermilab

    2007-06-01

    The present configuration of an ILC main LINAC RF station has 26 nine cell cavities driven from one klystron. With the addition of waveguide power coupler monitors, 96 RF signals will be down-converted and processed. A down-converter chassis is being developed that contains 12 eight channel analog modules and a single upconverter module. This chassis will first be deployed for testing a cryomodule composed of eight cavities located at New Muon Laboratory (NML) - Fermilab. Critical parts of the design for LLRF applications are identified and a detailed description of the circuit with various characteristic measurements is presented. The board is composed of an input band-pass filter centered at 1.3GHz, followed by a mixer, which down-converts the cavity probe signal to a proposed 13 MHz intermediate frequency. Cables with 8 channels per connector and good isolation between channels are being used to interconnect each down-converter module with a digital board. As mixers, amplifiers and power splitters are the most sensitive parts for noise, nonlinearities and crosstalk issues, special attention is given to these parts in the design of the LO port multiplication and distribution.

  7. A Safe Interaction of Robot Assisted Rehabilitation, Based on Model-Free Impedance Control with Singularity Avoidance

    Directory of Open Access Journals (Sweden)

    Iman Sharifi

    2014-12-01

    Full Text Available In this paper, a singularity-free control methodology for the safe robot-human interaction is proposed using a hybrid control technique in robotic rehabilitation applications. With the use of max-plus algebra, a hybrid controller is designed to guarantee feasible robot motion in the vicinity of the kinematic singularities or going through and staying at the singular configuration. The approach taken in this paper is based on model-free impedance control and hence does not require any information about the model except the upper bounds on the system matrix. The stability of the approach is investigated using multiple Lyapunov function theory. The proposed control algorithm is applied to PUMA 560 robot arm, a six-axis industrial robot. The results demonstrate the validity of the proposed control scheme.

  8. Rapid Modelling and Grinding of Workpieces’ Inner-surface by Robot with Impedance Model Based Fuzzy Force Control Algorithm

    Directory of Open Access Journals (Sweden)

    Wang Fei

    2017-01-01

    Full Text Available To achieve rapid automatic grinding of workpieces’ inner-surface by industrial robot, a rapid translational detection strategy of workpieces’ inner-surface and fuzzy force control algorithm of grinding are proposed in this paper. The rapid translational detection strategy introduces a way to establish an inner-surface’s model quickly by recording key points of the axial section contour which reflects big curvature changes of the contour. The established model is feasible but imprecision. The force control algorithm is based on impedance model. To promote adaptability to the imprecision of the established inner-surface’s model, a fuzzy adjusting strategy is introduced in the force control algorithm. By adopting an adjusting factor, which determined by force response and a fuzzy logic, the strategy can adjust the reference trajectory of impedance model in time. Taking advantage of proposed detection and force control method, grinding experiments shows that the contact normal force maintains approximately constant, the relative mean error is within 6.5%, and the material removal thickness of the inner-surface is approximately consistent. The proposed strategy’s feasibility is verified.

  9. An intelligent control framework for robot-aided resistance training using hybrid system modeling and impedance estimation.

    Science.gov (United States)

    Xu, Guozheng; Guo, Xiaobo; Zhai, Yan; Li, Huijun

    2015-08-01

    This study presents a novel therapy control method for robot-assisted resistance training using the hybrid system modeling technology and the estimated patient's bio-impedance changes. A new intelligent control framework based on hybrid system theory is developed, to automatically generate the desired resistive force and to make accommodating emergency behavior, when monitoring the changes of the impaired limb's muscle strength or the unpredictable safety-related occurrences during the execution of the training task. The impaired limb's muscle strength progress is online evaluated using its bio-damping and bio-stiffness estimation results. The proposed method is verified with a custom constructed therapeutic robot system featuring a Barrett WAM™ compliant manipulator. A typical inpatient stroke subject was recruited and enrolled in a ten-week resistance training program. Preliminary results show that the proposed therapeutic strategy can enhance the impaired limb's muscle strength and has practicability for robot-aided rehabilitation training.

  10. Mode Adaptive Droop Control with Virtual Output Impedances for an Inverter-Based Flexible AC Microgrid

    DEFF Research Database (Denmark)

    Kim, Jaehong; Guerrero, Josep M.; Rodriguez, Pedro;

    2011-01-01

    in islanded and grid-connected mode. The proposed control scheme does not need any mode switching action. Thus, it is relatively simple in control for full mode of operation. Smooth transitions between the operation modes and the effectiveness of the proposed control scheme are evaluated through simulation...... control combined with a derivative controller is used in islanded mode. In grid-connected mode, to strictly control the power factor in the point of common coupling (PCC), a droop method combined with an integral controller is adopted. Small-signal analysis of the proposed control is shown both...

  11. Hybrid-mode Impedance Control for Position/force Tracking in Motor-system Rehabilitation

    Directory of Open Access Journals (Sweden)

    Youngwoo Kim

    2015-06-01

    Full Text Available This paper proposes a new robot controller for motor-system rehabilitation. The proposed controller simultaneously realizes rehabilitation motion tracking and force generation, as predefined through a musculoskeletal model-based optimization process. We introduce control parameters of weighted control action priorities for the motion-tracking and force generation tasks, based on the position-tracking error. With the weighted control action priorities, the robot accords higher priority to motion tracking at the robot end point when the position-tracking error is larger than a threshold value, and to force generation when the position-tracking error is smaller than a threshold value. Smooth motion trajectory has to be designed and applied in robot-based rehabilitation. Through simulations and experimental results, we show the usefulness of the proposed control method.

  12. Mechanical Impedance Control in the Human Arm While Manually Transporting an Open-Top Fluid Filled Dish

    Directory of Open Access Journals (Sweden)

    Navit Roth

    2011-01-01

    Full Text Available The present study deals with stabilizing aspects of a hand-held dish filled with liquid while walking steadily. This is an attempt to decipher the neuro-muscular strategies employed and the mechanical responses of the arm during certain tasks of manual materials handling. The experimental configuration included a cup and the test-subject’s hand as an ‘end-effector’ of a serial three-link system representing the upper limb. These links are connected together by the wrist, elbow and shoulder joints. The tested subjects walked at constant speed on a treadmill while aiming to minimize liquid spillage from the cup. The motion of the limb and shoulder girdle served as inputs to a model to reveal the impedance adjustments during the simultaneous control of grasping and walking under ordinary conditions, and when one of the joints is affected. A regressive function used to express stiffness, included first-order dependence on angle and on angular velocity. The function used for damping included first-order dependence on angular velocity. Redundancies in the numerical solution were eliminated using multicollinearity diagnostic algorithms. The results revealed that the wrist joint was found to have constant stiffness and damping and no regulation of these coefficients was necessary during gait. Both in the elbow and shoulder joints stiffness included a constant coefficient as well as an angular velocity-dependent coefficient. Although all tested subjects demonstrated ability to prevent spillage of liquid, there was a considerable variability among the results obtained, indicating that the compensatory mechanisms employed by each subject to regulate the mechanical impedance were subjective. These results can help in the optimization of manual materials handeling tasks in industrial settings as well as future design of prosthetic arms, robotic appliances and man machine interfacing devices.

  13. Impedance source power electronic converters

    CERN Document Server

    Liu, Yushan; Ge, Baoming; Blaabjerg, Frede; Ellabban, Omar; Loh, Poh Chiang

    2016-01-01

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key features: Comprehensive analysis of the impedance source converter/inverter topologies, including typical topologies and derived topologies. Fully explains the design and control techniques of impedance source converters/inverters, including hardware design and control parameter design for corresponding control methods. Presents the latest power conversion solutions that aim to advance the role of pow...

  14. A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Galigekere, Veda Prakash;

    2016-01-01

    A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance S...... with an example single-switch 400 W dc-dc converter. For the closed-loop control design and stability assessment, a small signal model and its analysis of the proposed network are also presented in brief.......A novel A-source impedance network is proposed in this letter. The A-source impedance network uses an autotransformer for realizing converters for any application that demand a very high dc voltage gain. The network utilizes a minimal turns ratio compared to other Magnetically Coupled Impedance...

  15. Fuzzy-control-based five-step Li-ion battery charger by using AC impedance technique

    Science.gov (United States)

    Asadi, Houshyar; Aghay Kaboli, Seyed Hamidreza; Mohammadi, Arash; Oladazimi, Maysam

    2012-01-01

    In This paper the previous Li-Ion battery charger techniques are reviewed and compared and the new fuzzy logic battery charging method which is proposed to optimize and improve the battery charger efficiently. According to results of comparison, using the fuzzy control charging system can shorten the charging time with higher efficiency and lower temperature rise. Additionally, we have used optimal Li-ion battery charging frequency by using AC impedance technique which means if the battery is charged by the optimal charging frequency fZmin, that obtain from Bode Plot of the Li-ion battery, the charging time and charging efficiency will improve. Thus using the switching frequency (fZmin) of the battery charger and the fuzzy logic control on the same system can optimize the performance on the charging process. According to the experimental results, the proposed charger can charge the Li-ion batteries with higher efficiency 97.16%, lower temperature rise1.513degree celosias, fast charging period around 50.43 minute and long life cycle. The results in this paper are presented by using MATLAB and dsPIC30F2020 is used as controller applying designed fuzzy logic inside.

  16. On the Necessity of Including Joint Passive Dynamics in the Impedance Control of Robotic Legs

    Directory of Open Access Journals (Sweden)

    Juan Carlos Arevalo

    2014-07-01

    Full Text Available Bioinspired quadruped robots are among the best robot designs for field missions over the complex terrain encountered in extraterrestrial landscapes and disaster scenarios caused by natural and human-made catastrophes, such as those caused by nuclear power plant accidents and radiological emergencies. For such applications, the performance characteristics of the robots should include high mobility, adaptability to the terrain, the ability to handle a large payload and good endurance. Nature can provide inspiration for quadruped designs that are well suited for traversing complex terrain. Horse legs are an example of a structure that has evolved to exhibit good performance characteristics. In this paper, a leg design exhibiting the key features of horse legs is briefly described. This leg is an underactuated mechanism because it has two actively driven degrees of freedom (DOFs and one passively driven DOF. In this work, two control laws intended to be use in the stan ce phase are described: a control law that considers passive mechanism dynamics and a second law that neglects these dynamics. The performance of the two control laws is experimentally evaluated and compared. The results indicate that the first control law better achieves the control goal; however, the use of the second is not completely unjustified.

  17. On the Necessity of Including Joint Passive Dynamics in the Impedance Control of Robotic Legs

    Directory of Open Access Journals (Sweden)

    Juan Carlos Arevalo

    2014-07-01

    Full Text Available Bioinspired quadruped robots are among the best robot designs for field missions over the complex terrain encountered in extraterrestrial landscapes and disaster scenarios caused by natural and human-made catastrophes, such as those caused by nuclear power plant accidents and radiological emergencies. For such applications, the performance characteristics of the robots should include high mobility, adaptability to the terrain, the ability to handle a large payload and good endurance. Nature can provide inspiration for quadruped designs that are well suited for traversing complex terrain. Horse legs are an example of a structure that has evolved to exhibit good performance characteristics. In this paper, a leg design exhibiting the key features of horse legs is briefly described. This leg is an underactuated mechanism because it has two actively driven degrees of freedom (DOFs and one passively driven DOF. In this work, two control laws intended to be use in the stan ce phase are described: a control law that considers passive mechanism dynamics and a second law that neglects these dynamics. The performance of the two control laws is experimentally evaluated and compared. The results indicate that the first control law better achieves the control goal; however, the use of the second is not completely unjustified.

  18. A New Way of Controlling Parallel-Connected Inverters by Using Synchronous-Reference-Frame Virtual Impedance Loop—Part I: Control Principle

    DEFF Research Database (Denmark)

    Guan, Yajuan; Guerrero, Josep M.; Zhao, Xin

    2016-01-01

    A novel simple and effective autonomous current-sharing controller for parallel three-phase inverters is proposed in this paper. The proposed controller provides faster response and better accuracy in contrast to the conventional droop control, since this novel approach does not require any active...... or reactive power calculations. Instead, a synchronous-reference-frame (SRF) virtual impedance loop and an SRF-based phase-locked loop are used. Stationary analysis is provided in order to identify the inherent mechanism of the direct and quadrature output currents in relation to the voltage amplitude...... from a setup with three parallel 2.2 kW inverters verify the effectiveness of the proposed control strategy in different scenarios....

  19. Biased low differential input impedance current receiver/converter device and method for low noise readout from voltage-controlled detectors

    Science.gov (United States)

    Degtiarenko, Pavel V.; Popov, Vladimir E.

    2011-03-22

    A first stage electronic system for receiving charge or current from voltage-controlled sensors or detectors that includes a low input impedance current receiver/converter device (for example, a transimpedance amplifier), which is directly coupled to the sensor output, a source of bias voltage, and the device's power supply (or supplies), which use the biased voltage point as a baseline.

  20. Human-machine interaction force control:using a model-referenced adaptive impedance device to control an index finger exoskeleton

    Institute of Scientific and Technical Information of China (English)

    Qian BI; Can-jun YANG

    2014-01-01

    Exoskeleton robots and their control methods have been extensively developed to aid post-stroke rehabilitation. Most of the existing methods using linear controllers are designed for position control and are not suitable for human-machine interaction (HMI) force control, as the interaction system between the human body and exoskeleton is uncertain and nonlinear. We present an approach for HMI force control via model reference adaptive impedance control (MRAIC) to solve this problem in case of index finger exoskeleton control. First, a dynamic HMI model, which is based on a position control inner loop, is for-mulated. Second, the theoretical MRAC framework is implemented in the control system. Then, the adaptive controllers are designed according to the Lyapunov stability theory. To verify the performance of the proposed method, we compare it with a proportional-integral-derivative (PID) method in the time domain with real experiments and in the frequency domain with simu-lations. The results illustrate the effectiveness and robustness of the proposed method in solving the nonlinear HMI force control problem in hand exoskeleton.

  1. Power Flow Analysis Algorithm for Islanded LV Microgrids Including Distributed Generator Units with Droop Control and Virtual Impedance Loop

    DEFF Research Database (Denmark)

    Li, Chendan; Chaudhary, Sanjay; Vasquez, Juan Carlos

    2014-01-01

    ) consideration of virtual impedance parameters and (ii) higher accuracy in reactive power flow calculation. The improved power flow analysis algorithm proposed in this paper is validated by comparing the calculation results with detailed time domain simulation results. Case studies have been carried out...

  2. Impedance Source Power Electronic Converters

    DEFF Research Database (Denmark)

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

    Impedance Source Power Electronic Converters brings together state of the art knowledge and cutting edge techniques in various stages of research related to the ever more popular impedance source converters/inverters. Significant research efforts are underway to develop commercially viable...... and technically feasible, efficient and reliable power converters for renewable energy, electric transportation and for various industrial applications. This book provides a detailed understanding of the concepts, designs, controls, and application demonstrations of the impedance source converters/inverters. Key...... control methods. Presents the latest power conversion solutions that aim to advance the role of power electronics into industries and sustainable energy conversion systems. Compares impedance source converter/inverter applications in renewable energy power generation and electric vehicles as well...

  3. Robust stabilization control of power system based on the direct control of generator power by series variable impedance unit; Chokuretsu kahen inpidansu wo mochiita hatsudenki denryoku no chokusetsu seigyo ni yoru robasuto keito anteika seigyo

    Energy Technology Data Exchange (ETDEWEB)

    Hojo, M.; Mitani, Y.; Tuji, K. [Osaka University, Osaka (Japan)

    1997-06-20

    Advanced control system design method (whose application is believed to be difficult in practical use) with the advancement of technologies of power system stabilization controllers has received much attention. In particular, demand of stabilizing control system with high robustness is pointed out. Construction of linearization control system is proposed based on direct operating volume of electric output power`s generator using the series variable impedance unit in this paper. The results are summarized as follows. Based on direct control aim of a generator power out of system of controllers with reference to the swing characteristics of power generator under specification, a linearized control is manufactured. Proposed control based on simple construction using variable impedance unit which is connected continuously with transmission line is realized. Linear system which keeps eigen values pointed out by designers who predicts based on the use of proposed controller is obtained. 6 refs., 11 figs., 2 tabs.

  4. Electromechanical method coupling non-invasive skin impedance probing and in vivo subcutaneous liquid microinjection: controlling the diffusion pattern of nanoparticles within living soft tissues.

    Science.gov (United States)

    Sung, Baeckkyoung; Kim, Se Hoon; Lee, Jin-Kyu; Lee, Byung-Cheon; Soh, Kwang-Sup

    2014-08-01

    Transdermal drug delivery is the way to transport drug carriers, such as nanoparticles, across the skin barrier to the dermal and/or subcutaneous layer. In order to control the transdermal drug delivery process, based on the heterogeneous and nonlinear structures of the skin tissues, we developed a novel electromechanical method combining in vivo local skin impedance probing, subcutaneous micro-injection of colloidal nanoparticles, and transcutaneous electrical stimulation. Experiments on the nude mice using in vivo fluorescence imaging exhibited significantly different apparent diffusion patterns of the nanoparticles depending on the skin impedance: Anisotropic and isotropic patterns were observed upon injection into low and high impedance points, respectively. This result implies that the physical complexity in living tissues may cause anisotropic diffusion of drug carriers, and can be used as a parameter for controlling drug delivery process. This method also can be combined with microneedle-based drug release systems, micro-fabricated needle-electrodes, and/or advanced in vivo targeting/imaging technologies using nanoparticles.

  5. Percutaneous treatment of liver tumors with an adapted probe for cooled-tip, impedance-controlled radio-frequency ablation under open-magnet MR guidance: initial results

    Energy Technology Data Exchange (ETDEWEB)

    Kelekis, Alexis D.; Terraz, Sylvain; Roggan, Andre; Terrier, Francois; Majno, Pietro; Mentha, Gilles; Roth, Arnaud; Becker, Christoph D. [Department of Diagnostic and Interventional Radiology, University Hospital, 24 rue Micheli-du-Crest, 1211, Geneva (Switzerland)

    2003-05-01

    Percutaneous radio-frequency (RF) ablation of liver tumors is usually performed under guidance of real-time US, but some tumor nodules in some patients cannot be adequately visualized with this technique. We report our preliminary results with an MR-compatible, internally perfused 17-G RF probe adapted to a standard RF generator for impedance-controlled RF ablation under MR guidance. Following initial testing of the probe for MR compatibility, artifacts and macroscopic effects on an ex vivo pig liver, four patients with eight neoplastic liver nodules (five metastatic and three primary), which could not be properly targeted by US, were treated with the cooled-tip technique under MRI guidance in an open 0.23-T magnet. Metallic artifacts produced by the probe were useful for accurate placement and did not interfere with MRI monitoring at the end of the procedure. Based on imaging findings, the immediate result of RF was considered adequate in all instances. Local recurrence occurred in one instance after 6 months, requiring repeat treatment. No adverse effects were noted. Initial experience suggests that the probe we used allows to perform impedance-controlled cooled-tip RF ablation of liver tumors under open-magnet MR guidance. (orig.)

  6. Evaluation of the Trajectory Sensitivity Analysis of the DFIG Control Parameters in Response to Changes in Wind Speed and the Line Impedance Connection to the Grid DFIG

    Directory of Open Access Journals (Sweden)

    Mehdi Fooladgar

    2015-01-01

    Full Text Available Economic and environmental conditions often make large stations and transmission lines, restrictions are placed. Small and medium-sized production units connected to existing systems as a strategy is in progress. These units are usually near the center of the load placed and distributed generators (DG famous are the DG are allowed types vary, such as induction generators rack squirrel-connected wind turbines, generators fed induction double mounted wind turbines, fuel cells connected to the system by power electronic converters or synchronous generator connected to the turbine combustion [10]. This way sensitivity analysis in systems of distributed generation (DG is assessed. It is shown that the method can detect the effect of control parameters listed wind turbine connected to a double-fed induction generator (DFIG Badoou the impedance of the changing the speed of on the stability of the transmission line useful system invested. The control parameters of the importance of influencing the behavior of DFIG are divided.

  7. 机器人灵巧手柔性关节自适应阻抗控制%Adaptive impedance control for dexterous robot hand with elastic joint

    Institute of Scientific and Technical Information of China (English)

    樊绍巍; 宗华; 邱景辉; 陈兆芃

    2012-01-01

    This paper present recent results on the joint and Cartesian space impedance control for five-finger dexterous robot hand DLR-HIT II with elastic joints, based on joint torque feedback and nonlineari-ty compensation. Passivity based control strategy was implemented on HIT/DLR II dexterous robot hand, with modeling of the elastic joint on the robot hand. To improve the performance of the impedance controller, adaptive friction estimation with extended Kalman filter and gravity compensation based on Least Squares have been investigated on the robot hand. Experimental results show that, for the harmonic drive robot hand with joint torque feedback, accurate position tracking and stable torque/force response can be achieved with Cartesian and joint impedance controller with adaptive friction compensation.%针对具有柔性关节的HIT/DLR Ⅱ五指仿人机器人灵巧手,研究了基于关节力矩反馈和非线性补偿的关节空间和笛卡尔空间阻抗控制.通过建立柔性关节机器人灵巧手的控制模型,在HIT/DLR Ⅱ型灵巧手上实现基于无源性控制的柔性关节机器人阻抗控制策略.针对非线性摩擦力和重力对灵巧手阻抗控制的影响,基于扩展卡尔曼滤波器提出了自适应摩擦力观测器,实现了具有摩擦力补偿和基于最小二乘法优化重力补偿的机器人灵巧手自适应阻抗控制.实验结果表明,在具有谐波减速器等柔性环节的机器人灵巧手中,所提出的自适应阻抗控制器提高了位置控制的精确度,并获得了稳定的抓取力.

  8. Active impedance matching of complex structural systems

    Science.gov (United States)

    Macmartin, Douglas G.; Miller, David W.; Hall, Steven R.

    1991-01-01

    Viewgraphs on active impedance matching of complex structural systems are presented. Topics covered include: traveling wave model; dereverberated mobility model; computation of dereverberated mobility; control problem: optimal impedance matching; H2 optimal solution; statistical energy analysis (SEA) solution; experimental transfer functions; interferometer actuator and sensor locations; active strut configurations; power dual variables; dereverberation of complex structure; dereverberated transfer function; compensators; and relative power flow.

  9. Wakefields and coupling impedances

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. (Superconducting Super Collider Laboratory, 2550 Beckleymeade Ave., Dallas, Texas 75237 (United States))

    1995-02-01

    After a short introduction of the wake potentials and coupling impedances, a few new results in impedance calculations are discussed. The first example is a new analytical method for calculating impedances of axisymmetric structures in the low frequency range, below the cutoff frequency of the vacuum chamber. The second example demonstrates that even very small discontinuities on a smooth waveguide can result in appearance of trapped modes, with frequencies slightly below the waveguide cutoff frequency. The high-frequency (above the cutoff) behavior of the coupling impedance of many small discontinuities is discussed in the third example. [copyright] 1995 [ital American] [ital Institute] [ital of] [ital Physics

  10. Wakefields and coupling impedances

    Science.gov (United States)

    Kurennoy, Sergey

    1995-02-01

    After a short introduction of the wake potentials and coupling impedances, a few new results in impedance calculations are discussed. The first example is a new analytical method for calculating impedances of axisymmetric structures in the low frequency range, below the cutoff frequency of the vacuum chamber. The second example demonstrates that even very small discontinuities on a smooth waveguide can result in appearance of trapped modes, with frequencies slightly below the waveguide cutoff frequency. The high-frequency (above the cutoff) behavior of the coupling impedance of many small discontinuities is discussed in the third example.

  11. Impedance plethysmography of thoracic region: impedance cardiography.

    Directory of Open Access Journals (Sweden)

    Deshpande A

    1990-10-01

    Full Text Available Impedance plethysmograms were recorded from thoracic region in 254 normal subjects, 183 patients with coronary artery disease, 391 patients with valvular heart disease and 107 patients with congenital septal disorder. The data in 18 normal subjects and 55 patients showed that basal impedance decreases markedly during exercise in patients with ischaemic heart disease. Estimation of cardiac index by this technique in a group of 99 normal subjects has been observed to be more consistent than that of the stroke volume. Estimation of systolic time index from impedance plethysmograms in 34 normal subjects has been shown to be as reliable as that from electrocardiogram, phonocardiogram and carotid pulse tracing. Changes in the shape of plethysmographic waveform produced by valvular and congenital heart diseases are briefly described and the role of this technique in screening cardiac patients has been highlighted.

  12. Body composition of adult cystic fibrosis patients and control subjects as determined by densitometry, bioelectrical impedance, total-body electrical conductivity, skinfold measurements, and deuterium oxide dilution

    Energy Technology Data Exchange (ETDEWEB)

    Newby, M.J.; Keim, N.L.; Brown, D.L. (Univ. of California, Davis (USA))

    1990-08-01

    This study contrasts body compositions (by six methods) of eight cystic fibrosis (CF) subjects with those of eight control subjects matched for age, height, and sex. CF subjects weighed 84% as much as control subjects. Densitometry and two bioelectrical impedance-analysis methods suggested that reduced CF weights were due to less lean tissue (10.7, 9.5, and 10.4 kg). Total-body electrical conductivity (TOBEC) and skinfold-thickness measurements indicated that CF subjects were leaner than control subjects and had less fat (5.4 and 3.6 kg) and less lean (5.2 and 7 kg) tissue. D2O dilution showed a pattern similar to TOBEC (8.3 kg less lean, 2.7 kg less fat tissue). Densitometry estimates of fat (mass and percent) were not correlated (r less than 0.74, p greater than 0.05) with any other method for CF subjects but were correlated with all other methods for control subjects. CF subjects contained less fat and lean tissue than did control subjects. Densitometry by underwater weighing is unsuitable for assessing body composition of CF patients.

  13. RF control hardware design for CYCIAE-100 cyclotron

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Zhiguo, E-mail: bitbearAT@hotmail.com; Fu, Xiaoliang; Ji, Bin; Zhao, Zhenlu; Zhang, Tianjue; Li, Pengzhan; Wei, Junyi; Xing, Jiansheng; Wang, Chuan

    2015-11-21

    The Beijing Radioactive Ion-beam Facility project is being constructed by BRIF division of China Institute of Atomic Energy. In this project, a 100 MeV high intensity compact proton cyclotron is built for multiple applications. The first successful beam extraction of CYCIAE-100 cyclotron was done in the middle of 2014. The extracted proton beam energy is 100 MeV and the beam current is more than 20 μA. The RF system of the CYCIAE-100 cyclotron includes two half-wavelength cavities, two 100 kW tetrode amplifiers and power transmission line systems (all above are independent from each other) and two sets of Low Level RF control crates. Each set of LLRF control includes an amplitude control unit, a tuning control unit, a phase control unit, a local Digital Signal Process control unit and an Advanced RISC Machines based EPICS IOC unit. These two identical LLRF control crates share one common reference clock and take advantages of modern digital technologies (e.g. DSP and Direct Digital Synthesizer) to achieve closed loop voltage and phase regulations of the dee-voltage. In the beam commission, the measured dee-voltage stability of RF system is better than 0.1% and phase stability is better than 0.03°. The hardware design of the LLRF system will be reviewed in this paper.

  14. Impedance and Collective Effects

    CERN Document Server

    Metral, E; Rumolo, R; Herr, W

    2013-01-01

    This document is part of Subvolume C 'Accelerators and Colliders' of Volume 21 'Elementary Particles' of Landolt-Börnstein - Group I 'Elementary Particles, Nuclei and Atoms'. It contains the Chapter '4 Impedance and Collective Effects' with the content: 4 Impedance and Collective Effects Introduction 4.1 Space Charge 4.2 Wake Fields and Impedances 4.3 Coherent Instabilities 4.4 Landau Damping 4.5 Two-Stream Effects (Electron Cloud and Ions) 4.6 Beam-Beam Effects 4.7 Numerical Modelling

  15. High Gradient Operation with the CEBAF Upgrade RF Control System

    Energy Technology Data Exchange (ETDEWEB)

    J. Hovater; G. Davis; Hai Dong; Alicia Hofler; Lawrence King; John Musson; Tomasz Plawski

    2006-08-16

    The CEBAF Accelerator at Jefferson Lab is presently a 6 GeV five pass electron accelerator consisting of two superconducting linacs joined by independent magnetic transport arcs. Energy will be upgraded to 12 GeV with the addition of 10 new high gradient cryomodules (17+ MV/m). The higher gradients pose significant challenges beyond what the present analog low level RF (LLRF) control systems can handle reliably; therefore, a new LLRF control system is needed. A prototype system has been developed incorporating a large FPGA and using digital down and up conversion to minimize the need for analog components. The new system is more flexible and less susceptible to drifts and component nonlinearities. Because resonance control is critical to reach high gradients quickly, the new cryomodules will include a piezoelectric tuner for each cavity, and the LLRF controls must incorporate both feedback and feed-forward methods to achieve optimal resonance control performance. This paper discusses development of the new RF system, system performance for phase and amplitude stability and resonance control under Lorentz detuning measured during recent tests on a prototype cryomodule.

  16. Tracking of electrochemical impedance of batteries

    Science.gov (United States)

    Piret, H.; Granjon, P.; Guillet, N.; Cattin, V.

    2016-04-01

    This paper presents an evolutionary battery impedance estimation method, which can be easily embedded in vehicles or nomad devices. The proposed method not only allows an accurate frequency impedance estimation, but also a tracking of its temporal evolution contrary to classical electrochemical impedance spectroscopy methods. Taking into account constraints of cost and complexity, we propose to use the existing electronics of current control to perform a frequency evolutionary estimation of the electrochemical impedance. The developed method uses a simple wideband input signal, and relies on a recursive local average of Fourier transforms. The averaging is controlled by a single parameter, managing a trade-off between tracking and estimation performance. This normalized parameter allows to correctly adapt the behavior of the proposed estimator to the variations of the impedance. The advantage of the proposed method is twofold: the method is easy to embed into a simple electronic circuit, and the battery impedance estimator is evolutionary. The ability of the method to monitor the impedance over time is demonstrated on a simulator, and on a real Lithium ion battery, on which a repeatability study is carried out. The experiments reveal good tracking results, and estimation performance as accurate as the usual laboratory approaches.

  17. Impedance and component heating

    CERN Document Server

    Métral, E; Mounet, N; Pieloni, T; Salvant, B

    2015-01-01

    The impedance is a complex function of frequency, which represents, for the plane under consideration (longitudinal, horizontal or vertical), the force integrated over the length of an element, from a “source” to a “test” wave, normalized by their charges. In general, the impedance in a given plane is a nonlinear function of the test and source transverse coordinates, but it is most of the time sufficient to consider only the first few linear terms. Impedances can influence the motion of trailing particles, in the longitudinal and in one or both transverse directions, leading to energy loss, beam instabilities, or producing undesirable secondary effects such as excessive heating of sensitive components at or near the chamber wall, called beam-induced RF heating. The LHC performance limitations linked to impedances encountered during the 2010-2012 run are reviewed and the currently expected situation during the HL-LHC era is discussed.

  18. The LEP impedance model

    Energy Technology Data Exchange (ETDEWEB)

    Zotter, B. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    This report describes a number of measurements and computations of the impedance of the Large Electron Positron collider LEP at CERN. The work has been performed over several years, together with D. Brandt, K. Cornelis, A. Hofmann, G. Sabbi and many others. The agreement between measurements of single bunch instabilities on the machine and computer simulations is in general excellent and gives confidence in the impedance model used. (author)

  19. Robot Impedance Control Method Adapting to Unknown or Changing Environment Stiffness and Damping Parameters%适应环境刚度、阻尼参数未知或变化的机器人阻抗控制方法

    Institute of Scientific and Technical Information of China (English)

    李正义; 曹汇敏

    2014-01-01

    针对机器人阻抗控制在实际应用中其性能受环境的阻尼、刚度参数未知或变化影响的问题,提出了一种机器人自适应阻抗控制方法。在定义机器人阻抗控制性能指标的基础上结合阻抗模型刚度变化的几何表示,给出了阻抗模型刚度参数初值计算方法,提出了基于人工神经网络的环境等效刚度在线估计方法,并结合二阶系统临界阻尼条件计算阻抗模型阻尼参数初值。机器人力控制实验结果验证了该方法较已有的机器人阻抗控制方法在参考轨迹平滑性、力控制稳定性和易于工程实践方面有一定的优势。%The robot impedance control performance decreases with the efffects of changing or un-known environment stiffness and damping parameters in practical applications ,this paper presented a self-adaptive robot impedance control method to resolve this problem .Based on the definition of the robot impedance control performance index and the geometric representation for the impedance model stiffness variation ,the calculation method was illustrated for intitial values of the the impedance mod-el stiffness .Designing an artificial neural network to estimate the environmental equivalent stiffness online and combining with critical damping condition of the second-order system ,a calculation method was provided for the impedance model damping initial values .The results of robot force control experi-ments demonstrate smoother reference trajectory ,improved robot force control stability and feasibility in practices compared to the existing robot impedance control methods.

  20. Battery impedance spectroscopy using bidirectional grid connected converter

    Indian Academy of Sciences (India)

    SHIMUL KUMAR DAM; VINOD JOHN

    2017-08-01

    Battery impedance can provide valuable insight into the condition of the battery. Commercially available impedance measurement instruments are expensive. Hence their direct use in a battery management system is not justifiable. In this work, a 3-kW bi-directional converter for charging and discharging a batterybank has been implemented with the capability of impedance measurement. The converter is grid connected and controlled to operate at unity power factor. Additional requirements on filter design and control structure of battery converter for impedance measurement are discussed. An algorithm has been developed to measure impedance by frequency sweep, avoiding transients. The measured impedance has been compared to that from a commercially available impedance measurement equipment and is shown to have a good match.

  1. Impedance adaptation for optimal robot-environment interaction

    Science.gov (United States)

    Ge, Shuzhi Sam; Li, Yanan; Wang, Chen

    2014-02-01

    In this paper, impedance adaptation is investigated for robots interacting with unknown environments. Impedance control is employed for the physical interaction between robots and environments, subject to unknown and uncertain environments dynamics. The unknown environments are described as linear systems with unknown dynamics, based on which the desired impedance model is obtained. A cost function that measures the tracking error and interaction force is defined, and the critical impedance parameters are found to minimise it. Without requiring the information of the environments dynamics, the proposed impedance adaptation is feasible in a large number of applications where robots physically interact with unknown environments. The validity of the proposed method is verified through simulation studies.

  2. Finemet cavity impedance studies

    CERN Document Server

    Persichelli, S; Migliorati, M; Salvant, B

    2013-01-01

    The aim of the study is to evaluate the impedance of the Finemet kicker cavity to be installed in the PS straight section 02 during LS1, under realistic assumptions of bunch length. Time domain simulations with CST Particle Studio have been performed in order to get the impedance of the cavity and make a comparison with the longitudinal impedance measured for a single cell prototype. The study has been performed on simplified 3D geometries imported from a mechanical CATIA drawing, assuming that the simplications have small impact on the nal results. Simulations confirmed that the longitudinal impedance observed with measurements can be excited by bunches circulating in the PS. In the six-cells Finemet cavity, PS bunches circulating in the center can excite a longitudinal impedance, the real part of which has a maximum of 2 kOhm at 4 MHz. This mode does not seem to have any transverse component. All the eigenmodes of the cavity are strongly damped by the Finemet rings: we predict to have no issues regarding tr...

  3. Impedance modelling of pipes

    Science.gov (United States)

    Creasy, M. Austin

    2016-03-01

    Impedance models of pipes can be used to estimate resonant frequencies of standing waves and model acoustic pressure of closed and open ended pipes. Modelling a pipe with impedance methods allows additional variations to the pipe to be included in the overall model as a system. Therefore an actuator can be attached and used to drive the system and the impedance model is able to include the dynamics of the actuator. Exciting the pipe system with a chirp signal allows resonant frequencies to be measured in both the time and frequency domain. The measurements in the time domain are beneficial for introducing undergraduates to resonances without needing an understanding of fast Fourier transforms. This paper also discusses resonant frequencies in open ended pipes and how numerous texts incorrectly approximate the resonant frequencies for this specific pipe system.

  4. Impeded Dark Matter

    CERN Document Server

    Kopp, Joachim; Slatyer, Tracy R; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider a new class of thermal dark matter models, dubbed "Impeded Dark Matter", in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. We demonstrate that either case can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonstrate that the annihilation cross-section for Impeded Dark Matter depends linearly on the dark matter velocity or may even be kinematically forbidden, making this scenario almost insensitive to constraints from the cosmic microwave background and from observations of dwarf galaxies. Accordingly, it may be possible for Impeded Dark Matter to yield observable signals in clusters or the Galactic center, with no corresponding signal in dwarfs. For positive mass splitting, we show that the annihilation cross-section is suppress...

  5. Development of Low Level RF Control Systems for Superconducting Heavy Ion Linear Accelerators, Electron Synchrotrons and Storage Rings

    CERN Document Server

    Aminov, Bachtior; Kolesov, Sergej; Pekeler, Michael; Piel, Christian; Piel, Helmut

    2005-01-01

    Since 2001 ACCEL Instruments is supplying low level RF control systems together with turn key cavity systems. The early LLRF systems used the well established technology based on discrete analogue amplitude and phase detectors and modulators. Today analogue LLRF systems can make use of advanced vector demodulators and modulators combined with a fast computer controlled analogue feed back loop. Feed forward control is implemented to operate the RF cavity in an open loop mode or to compensate for predictable perturbations. The paper will introduce the general design philosophy and show how it can be adapted to different tasks as controlling a synchrotron booster nc RF system at 500 MHz, or superconducting storage ring RF cavities, as well as a linear accelerator at 176 MHz formed by a chain of individually driven and controlled superconducting λ/2 cavities.

  6. Negative transverse impedance

    Energy Technology Data Exchange (ETDEWEB)

    Chou, W.

    1989-06-12

    Recently, measurements in the SPS show that the coherent tune shift in the horizontal direction has positive values whereas that in the vertical direction has negative ones. Thus the existence of negative transverse impedance gets confirmed in a real machine. This stimulates us to start a new round of systematic studies on this interesting phenomenon. The results obtained from our computer simulations are presented in this note. Our simulations demonstrate that the negative transverse impedance may appear when the rotational symmetry embedded in a discontinuity is broken, and that the geometries that we have studies may be the source of the positive horizontal tune shift measured in the SPS.

  7. Impedance of accelerator components

    Energy Technology Data Exchange (ETDEWEB)

    Corlett, J.N. [Center for Beam Physics, Lawrence Berkeley National Laboratory, I Cyclotron Road, Berkeley, California 94720 (United States)

    1997-01-01

    As demands for high luminosity and low emittance particle beams increase, an understanding of the electromagnetic interaction of these beams with their vacuum chamber environment becomes more important in order to maintain the quality of the beam. This interaction is described in terms of the wake field in time domain, and the beam impedance in frequency domain. These concepts are introduced, and related quantities such as the loss factor are presented. The broadband Q=1 resonator impedance model is discussed. Perturbation and coaxial wire methods of measurement of real components are reviewed. {copyright} {ital 1997 American Institute of Physics.}

  8. Longitudinal impedance of RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Brennan, J. M. [Brookhaven National Lab. (BNL), Upton, NY (United States); Mernick, K. [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-05-03

    The longitudinal impedance of the two RHIC rings has been measured using the effect of potential well distortion on longitudinal Schottky measurements. For the blue RHIC ring Im(Z/n) = 1.5±0.2Ω. For the yellow ring Im(Z/n) = 5.4±1Ω.

  9. Impedance plethysmography: basic principles.

    Directory of Open Access Journals (Sweden)

    Babu J

    1990-04-01

    Full Text Available Impedance Plethysmography technique has been discussed with explanation of two compartment model and parallel conductor theory for the estimation of peripheral blood flow and stroke volume. Various methods for signal enhancement to facilitate computation of blood flow are briefly described. Source of error in the estimation of peripheral blood flow is identified and the correction has been suggested.

  10. Implantable Impedance Plethysmography

    OpenAIRE

    2014-01-01

    We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed as an implant to monitor cardiac events and arteriosclerotic progression over the long term.

  11. Implantable Impedance Plethysmography

    Directory of Open Access Journals (Sweden)

    Michael Theodor

    2014-08-01

    Full Text Available We demonstrate by theory, as well as by ex vivo and in vivo measurements that impedance plethysmography, applied extravascularly directly on large arteries, is a viable method for monitoring various cardiovascular parameters, such as blood pressure, with high accuracy. The sensor is designed as an implant to monitor cardiac events and arteriosclerotic progression over the long term.

  12. Low-level RF LabVIEW{reg_sign} control software user`s manual: Version 1.0

    Energy Technology Data Exchange (ETDEWEB)

    1992-06-01

    This document details information on the low-level radio frequency (LLRF) software control package. The chapters in this manual cover the following topics: Chapter one describes the general operating principles of the LabVIEW software package, and also discusses the high-level menu panels which allow access to the individual control panels. Chapter two covers the control panels used for conditioning the cavity, and for controlling the accelerator under normal operating conditions. Chapter three provides information on the resonance detection and reflectometer calibration function, including the setup and status panels for each. Chapter four contain instructions on the use of those panels dedicated to controlling the cavity RF field. Chapter five discusses the control panels that provide setup and status information on the diagnostic monitor subsystem. Chapter six outlines those panels used to control the timing functions provided by the LLRF system. Finally, chapter seven describes the control panels used to monitor and adjust the alarm and limit functions of the system. Throughout the document, it is assumed that the reader has a general working knowledge of accelerators, high-power amplifier equipment, and low-level RF (LLRF) control systems. References are listed as footnotes as they occur in the text.

  13. Antenna impedance matching with neural networks.

    Science.gov (United States)

    Hemminger, Thomas L

    2005-10-01

    Impedance matching between transmission lines and antennas is an important and fundamental concept in electromagnetic theory. One definition of antenna impedance is the resistance and reactance seen at the antenna terminals or the ratio of electric to magnetic fields at the input. The primary intent of this paper is real-time compensation for changes in the driving point impedance of an antenna due to frequency deviations. In general, the driving point impedance of an antenna or antenna array is computed by numerical methods such as the method of moments or similar techniques. Some configurations do lend themselves to analytical solutions, which will be the primary focus of this work. This paper employs a neural control system to match antenna feed lines to two common antennas during frequency sweeps. In practice, impedance matching is performed off-line with Smith charts or relatively complex formulas but they rarely perform optimally over a large bandwidth. There have been very few attempts to compensate for matching errors while the transmission system is in operation and most techniques have been targeted to a relatively small range of frequencies. The approach proposed here employs three small neural networks to perform real-time impedance matching over a broad range of frequencies during transmitter operation. Double stub tuners are being explored in this paper but the approach can certainly be applied to other methodologies. The ultimate purpose of this work is the development of an inexpensive microcontroller-based system.

  14. Impedance calculation for ferrite inserts

    Energy Technology Data Exchange (ETDEWEB)

    Breitzmann, S.C.; Lee, S.Y.; /Indiana U.; Ng, K.Y.; /Fermilab

    2005-01-01

    Passive ferrite inserts were used to compensate the space charge impedance in high intensity space charge dominated accelerators. They study the narrowband longitudinal impedance of these ferrite inserts. they find that the shunt impedance and the quality factor for ferrite inserts are inversely proportional to the imaginary part of the permeability of ferrite materials. They also provide a recipe for attaining a truly passive space charge impedance compensation and avoiding narrowband microwave instabilities.

  15. Acoustic ground impedance meter

    Science.gov (United States)

    Zuckerwar, A. J. (Inventor)

    1984-01-01

    A method and apparatus are presented for measuring the acoustic impedance of a surface in which the surface is used to enclose one end of the chamber of a Helmholz resonator. Acoustic waves are generated in the neck of the resonator by a piston driven by a variable speed motor through a cam assembly. The acoustic waves are measured in the chamber and the frequency of the generated acoustic waves is measured by an optical device. These measurements are used to compute the compliance and conductance of the chamber and surface combined. The same procedure is followed with a calibration plate having infinite acoustic impedance enclosing the chamber of the resonator to compute the compliance and conductance of the chamber alone. Then by subtracting, the compliance and conductance for the surface is obtained.

  16. Tensor Impedance Surfaces

    Science.gov (United States)

    2010-11-30

    ELECTROMAGNEETIC SURFACE IMPEDANCE PROPERTIES FA9550-09-C-0198 DR. ADOUR KABAKIAN HUGHES RESEARCH LABS AFOSR / RSE 875 North Randolph Street, Suit...325 Room 3112 Arlington, Virginia 22203-1768 AFOSR / RSE AFRL-OSR-VA-TR-2012-0770 Distribution A We have investigated and determined how the tensor...the case of a TM wave, which favors propagation along the shorter principal axis. Standard terms apply U U U UU Arje Nachman RSE (Program Manager

  17. Impeded Dark Matter

    OpenAIRE

    Kopp, Joachim; Liu, Jia; Slatyer, Tracy R.; Wang, Xiao-Ping; Xue, Wei

    2016-01-01

    We consider a new class of thermal dark matter models, dubbed "Impeded Dark Matter", in which the mass splitting between the dark matter particles and their annihilation products is tiny. Compared to the previously proposed Forbidden Dark Matter scenario, the mass splittings we consider are much smaller, and are allowed to be either positive or negative. We demonstrate that either case can be easily realized without requiring tuning of model parameters. For negative mass splitting, we demonst...

  18. Acoustic impedances of ear canals measured by impedance tube

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2007-01-01

    During hearing sensitivity tests, the sound field is commonly generated by an earphone placed on a subject ear. One of the factors that can affect the sound transmission in the ear is the acoustic impedance of the ear canal. Its importance is related to the contribution of other elements involved...... in the transmission such as the earphone impedance. In order to determine the acoustic impedances of human ear canals, the standardized method for measurement of complex impedances used for the measurement of the audiometric earphone impedances is applied. It is based on the transfer function between two microphone...... locations in an impedance tube. The end of the tube representing the measurement plane is placed at the ear canal entrance. Thus, the impedance seen from the entrance inward is measured on 25 subjects. Most subjects participated in the previous measurement of the ratio between the pressures at the open...

  19. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S. [Stanford Linear Accelerator Center, Menlo Park, CA (United States)

    1996-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impedance. This paper discusses three aspects of broadband impedance modelling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f. cavity. The last is a discussion of requirements for the mathematical form of an impedance which follow from the general properties of impedances. (author)

  20. Robust Two Degrees-of-freedom Single-current Control Strategy for LCL-type Grid-Connected DG System under Grid-Frequency Fluctuation and Grid-impedance Variation

    DEFF Research Database (Denmark)

    Zhou, Leming; Chen, Yandong; Luo, An

    2016-01-01

    For LCL-type grid-connected distributed generation(DG) system, the grid-frequency fluctuation and grid-impedance variation affect the active/reactive power control accuracy and resonance peak suppression respectively, which would reduce the system robustness. In this paper, a robust two degrees-of-freedom......-state performances. The stability margin and dynamic response of the overall system are analyzed in detail, and the proper parameters are selected without complicated trial. Finally, Simulation and experimental results verify the proposed control and design strategies....

  1. Fundamental impedance characteristics and control strategy for TCSC with dual-TCR branches%双TCR支路型TCSC基波阻抗特性和控制策略仿真研究

    Institute of Scientific and Technical Information of China (English)

    郝鑫杰; 戴朝波; 宋晓通; 李生虎; 李欣

    2012-01-01

    为了满足电力系统对特高压线路可控性和安全性的要求,可以在特高压线路上加装TCSC(Thyristor Controlled Series Capacitor).而特高压的高电压和大电流对TCSC造成了考验,即大幅度提高TCSC的额定电流时,流过晶闸管阀支路的电流随之增加,有可能超过晶闸管的通流能力极限.提出在单TCR(Thyristor Controlled Reactor)支路型TCSC结构上,再增加一条TCR支路实现对大电流分流.TCR支路增加了控制复杂性,首先由于阀控电抗器的制造误差、测量误差等的存在,会引起流过两条TCR支路电流不均流,严重时损坏阀体,故需要增加均流的控制措施;其次阻抗表是TCSC实现阻抗跟踪的基础,计及均流要求的阻抗解析算法复杂度高.在研究双TCR型TCSC基波阻抗特性的基础上,提出了求取阻抗表的简便方法.%In order to satisfy the controllability and security requirement for power systems, the TCSC (Thyristor Controlled Series Capacitor) is installed on the UHV (Ultra High Voltage) line. The UHV and high current become the challenge to TCSC , i. e. with the substantial increase of the rated current of the TCSC, the current flowing through the thyristor branch should also be improved, which may exceed the current limit of thyristor. A TCSC scheme with an extra TCR branch in parallel is proposed, which can shunt the large current. The dual TCRs will inevitably increase the control complexity. Firstly the manufacturing error and measurement error of valve-controlled reactor will make the current between the two TCR branches not equal, which will damage the thyristor in severe conditions, therefore current-balancing control is needed. Secondly, the impedance table is the basis for TCSC control. Considering current-balancing characteristics of dual TCRs, the analytical algorithm of impedance table of TCSC with both TCRs is complicated. On the basis of studying of impedance characteristics of dual TCRs, a simple method is

  2. Lower leg electrical impedance after distal bypass surgery

    DEFF Research Database (Denmark)

    Belanger, G K; Bolbjerg, M L; Heegaard, N H

    1998-01-01

    Electrical impedance was determined in 13 patients following distal bypass surgery to evaluate lower leg oedema as reflected by its circumference. Tissue injury was assessed by the plasma concentration of muscle enzymes. After surgery, the volume of the control lower leg increased from 1250 (816...... of troponin I (n = 8). In conclusion, tissue injury was reflected by increases in muscle enzymes in plasma. We found an inverse correlation between lower leg electrical impedance and volume, but the deviation in electrical impedance was approximately twice that of the leg volume. Electrical impedance appears...

  3. Impedance characterization of PV modules in outdoor conditions

    DEFF Research Database (Denmark)

    Oprea, Matei-lon; Thorsteinsson, Sune; Spataru, Sergiu;

    2016-01-01

    Impedance spectroscopy (IS) has been used for laboratory characterizations of photovoltaic (PV) technologies under well controlled conditions. This work applies IS for outdoor characterization of PV panels, in order to observe the effect of irradiance (G) and temperature (T) on the PV module’s...... impedance spectrum, and further construct an impedance model that can link environmental changes to the model’s parameters. To achieve this, an optimized setup has been developed for long-term impedance spectra monitoring synchronised with accurate irradiance and temperature data. Preliminary results show...

  4. Microgrid Reactive and Harmonic Power Sharing Using Enhanced Virtual Impedance

    DEFF Research Database (Denmark)

    He, Jinwei; Wei Li, Yun; Guerrero, Josep M.

    2013-01-01

    To address the load sharing problem in islanding microgrids, this paper proposes an improved approach which regulates the distributed generation (DG) unit interfacing virtual impedance at fundamental and selected harmonic frequencies. In contrast to the conventional virtual impedance control where...... feeder impedances can be properly compensated, resulting in accurate reactive and harmonic power sharing at the same time. In addition, this paper shows that the microgrid PCC harmonic voltages can be mitigated by reducing the magnitude of DG unit equivalent harmonic impedance. Finally, an improved...

  5. Impedance force control for position controlled robotic manipulators under the constraint of unknown environments%受未知环境约束的位控操作机器人臂阻抗力控制

    Institute of Scientific and Technical Information of China (English)

    乔兵; 陆荣鑑

    2003-01-01

    提出了一种面向位控操作机器人臂的阻抗力控制策略.利用在线力反馈数据对未知约束环境的形状进行估计以获得接触点处的环境切矢和法矢,根据该切矢和法矢实时生成目标阻抗模型的虚拟参考运动轨迹,在力误差信号的驱动下由目标阻抗模型产生机器人的指令运动轨迹,通过跟踪该指令运动轨迹机器人臂能够保持和未知约束环境的接触跟踪并将力误差限制在可接受的范围之内,力误差信号的动态行为与目标阻抗模型一致.为了验证控制策略的未知约束环境跟踪能力和力控制能力,以一个三杆平面机器人为例进行了计算机仿真,并在Adept-3精密装配机器人上进行了玻璃灯泡表面恒力跟踪的实验研究,仿真和实验结果表明文中提出的策略具有很好的未知表面跟踪和力控制能力.%A force control strategy for position controlled robotic manipulators is presented. On-line force feedback data are employed to estimate the local shape of the unknown constraint. The estimated vectors are used to generate the virtual reference trajectory for the target impedance model that is driven by the force error to produce command position. By following the command position trajectory the robotic manipulator can follow the unknown constraint surface while keeping an acceptable force error in a manner depicted by the target impedance model. Computer simulation on a 3-linked planar manipulator and experimental studies on an Adept-3, an SCARA type robotic manipulator, are conducted to verify the force tracking capability of the proposed control strategy.

  6. Bioelectrical impedance analysis--part I

    DEFF Research Database (Denmark)

    Kyle, Ursula G; Bosaeus, Ingvar; De Lorenzo, Antonio D;

    2004-01-01

    The use of bioelectrical impedance analysis (BIA) is widespread both in healthy subjects and patients, but suffers from a lack of standardized method and quality control procedures. BIA allows the determination of the fat-free mass (FFM) and total body water (TBW) in subjects without significant ...

  7. Impedance group summary

    Science.gov (United States)

    Blaskiewicz, M.; Dooling, J.; Dyachkov, M.; Fedotov, A.; Gluckstern, R.; Hahn, H.; Huang, H.; Kurennoy, S.; Linnecar, T.; Shaposhnikova, E.; Stupakov, G.; Toyama, T.; Wang, J. G.; Weng, W. T.; Zhang, S. Y.; Zotter, B.

    1999-12-01

    The impedance working group was charged to reply to the following 8 questions relevant to the design of high-intensity proton machines such as the SNS or the FNAL driver. These questions were first discussed one by one in the whole group, then each ne of them assigned to one member to summarize. On the lst morning these contributions were publicly read, re-discussed and re-written where required—hence they are not the opinion of a particular person, but rather the averaged opinion of all members of the working group. (AIP)

  8. Modified impedance source inverter for power conditioning system

    Indian Academy of Sciences (India)

    J SUGANTHI; M RAJARAM

    2017-03-01

    Based on classical impedance source inverter concept, this paper presents a modified impedance source inverter controlled by different pulse width modulation control strategies for solar PV/battery-powered applications. A brief topology analysis, generalized discussion and design of impedance network elements are presented. Comparison with the classical impedance source inverter is presented. Using simulation, analytical results are presented that ensure stability. The proposed voltage type inverter has reduced inrush current at startup, less capacitor voltage stress and minimum inductor current ripples. DC link voltage boost, reduced total harmonic distortion of output current and voltage, better voltage gain and wide range of output voltage controlcan be achieved easily with improved power quality. Experimental set-up of the modified impedance source inverter with Field Programmable Gate Array (FPGA) controller has been constructed to ascertain the results.

  9. Outdoor ground impedance models.

    Science.gov (United States)

    Attenborough, Keith; Bashir, Imran; Taherzadeh, Shahram

    2011-05-01

    Many models for the acoustical properties of rigid-porous media require knowledge of parameter values that are not available for outdoor ground surfaces. The relationship used between tortuosity and porosity for stacked spheres results in five characteristic impedance models that require not more than two adjustable parameters. These models and hard-backed-layer versions are considered further through numerical fitting of 42 short range level difference spectra measured over various ground surfaces. For all but eight sites, slit-pore, phenomenological and variable porosity models yield lower fitting errors than those given by the widely used one-parameter semi-empirical model. Data for 12 of 26 grassland sites and for three beech wood sites are fitted better by hard-backed-layer models. Parameter values obtained by fitting slit-pore and phenomenological models to data for relatively low flow resistivity grounds, such as forest floors, porous asphalt, and gravel, are consistent with values that have been obtained non-acoustically. Three impedance models yield reasonable fits to a narrow band excess attenuation spectrum measured at short range over railway ballast but, if extended reaction is taken into account, the hard-backed-layer version of the slit-pore model gives the most reasonable parameter values.

  10. Biomass production and control of nutrient leaching of willows using different planting methods with special emphasis on an appraisal of the electrical impedance for roots

    Energy Technology Data Exchange (ETDEWEB)

    Yang Cao

    2011-07-01

    Willow reproduction can be achieved through vertically or horizontally planted cuttings. Conventionally, plantations are established by inserting cuttings vertically into the soil. There is, however, a lack of information about the biomass production and nutrient leaching of plantations established through horizontally planted cuttings. A greenhouse experiment and a field trial were carried out to investigate whether horizontally planted Salix schwerinii cuttings have a positive effect on stem yield, root distribution and nutrient leaching in comparison with vertically planted cuttings with different planting densities. The shoots' height of horizontally planted cuttings was significantly smaller than that of vertically planted cuttings during the first two weeks after planting in the pot experiment. Thereafter, no significant effect of planting orientation on the stem biomass was observed in the two conducted experiments. In both experiments the total stem biomass increased with the planting density. It was also found that the fine root biomass and the specific root length were not affected by the planting orientation or density, while the fine root surface area and the absorbing root surface area (ARSA) were affected only by the planting density. The planting orientation did not affect the nutrient concentrations in the soil leachate, apart from SO{sub 4}-S and PO{sub 4}-P in the pot experiment. The ARSA in the pot experiment was assessed by using the earth impedance method. The applicability of this method was evaluated in a hydroponic study of willow cuttings where root and stem were measured independently. Electrical resistance had a good correlation with the contact area of the roots with the solution. However, the resistance depended strongly on the contact area of the stem with the solution, which caused a bias in the evaluation of root surface area. A similar experimental set-up with electrical impedance spectroscopy was employed to study the

  11. Electrical impedance tomography of electrolysis.

    Science.gov (United States)

    Meir, Arie; Rubinsky, Boris

    2015-01-01

    The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT). The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations.

  12. Electrical impedance tomography of electrolysis.

    Directory of Open Access Journals (Sweden)

    Arie Meir

    Full Text Available The primary goal of this study is to explore the hypothesis that changes in pH during electrolysis can be detected with Electrical Impedance Tomography (EIT. The study has relevance to real time control of minimally invasive surgery with electrolytic ablation. To investigate the hypothesis, we compare EIT reconstructed images to optical images acquired using pH-sensitive dyes embedded in a physiological saline agar gel phantom treated with electrolysis. We further demonstrate the biological relevance of our work using a bacterial E.Coli model, grown on the phantom. The results demonstrate the ability of EIT to image pH changes in a physiological saline phantom and show that these changes correlate with cell death in the E.coli model. The results are promising, and invite further experimental explorations.

  13. Microwave Impedance Measurement for Nanoelectronics

    Directory of Open Access Journals (Sweden)

    M. Randus

    2011-04-01

    Full Text Available The rapid progress in nanoelectronics showed an urgent need for microwave measurement of impedances extremely different from the 50Ω reference impedance of measurement instruments. In commonly used methods input impedance or admittance of a device under test (DUT is derived from measured value of its reflection coefficient causing serious accuracy problems for very high and very low impedances due to insufficient sensitivity of the reflection coefficient to impedance of the DUT. This paper brings theoretical description and experimental verification of a method developed especially for measurement of extreme impedances. The method can significantly improve measurement sensitivity and reduce errors caused by the VNA. It is based on subtraction (or addition of a reference reflection coefficient and the reflection coefficient of the DUT by a passive network, amplifying the resulting signal by an amplifier and measuring the amplified signal as a transmission coefficient by a common vector network analyzer (VNA. A suitable calibration technique is also presented.

  14. Mechanism and Impedance Control of the Ball Universal Joint Robot Driven by the Pneumatic Muscle Actuator Group%基于气动肌肉群驱动球关节机器人结构及阻抗控制

    Institute of Scientific and Technical Information of China (English)

    刘昱; 王涛; 范伟

    2013-01-01

    气动肌肉(Pneumatic muscle actuator,PMA)是仿生机器人研究的重点,为此,设计一种由气动肌肉群驱动的3自由度球关节机器人,并对其进行运动学分析.根据其运动学逆解,提出气动肌肉群位置控制策略;同时,提出基于运动学逆解及能量最优原则气动肌肉群力控制策略;设计基于气动肌肉位置群及力群的含位置PID内环的阻抗控制器.试验结果表明,单纯的位置控制精度比较高,可达0.3°,但造成输出力矩失控;阻抗控制虽然在一定程度上牺牲了位置控制精度,但可以对输出力矩进行柔顺控制.%Pneumatic muscle actuator (PMA) is the research focus of bionic robot.Therefore,a triaxial-ball universal joint robot driven by the PMA group is designed.The kinematics of the robot is analysed.On the basis of its kinematics analysis,the position control strategy of the PMA group is proposed.Based on the kinematics analysis and the energy saving principle,the contact force control strategy of the PMA group is proposed.An impedance control scheme with inner position PID loop is designed for the PMA group.Results show that under position control only,the control accuracy is higher than impedance control and the steady-error is less than 0.3°,however,the contact force is out of control.Impedance control sacrifices a certain degree of position control accuracy but can realize compliant control of contact force.

  15. Optically stimulated differential impedance spectroscopy

    Science.gov (United States)

    Maxey, Lonnie C; Parks, II, James E; Lewis, Sr., Samuel A; Partridge, Jr., William P

    2014-02-18

    Methods and apparatuses for evaluating a material are described. Embodiments typically involve use of an impedance measurement sensor to measure the impedance of a sample of the material under at least two different states of illumination. The states of illumination may include (a) substantially no optical stimulation, (b) substantial optical stimulation, (c) optical stimulation at a first wavelength of light, (d) optical stimulation at a second wavelength of light, (e) a first level of light intensity, and (f) a second level of light intensity. Typically a difference in impedance between the impedance of the sample at the two states of illumination is measured to determine a characteristic of the material.

  16. IMPEDANCE OF FINITE LENGTH RESISTOR

    Energy Technology Data Exchange (ETDEWEB)

    KRINSKY, S.; PODOBEDOV, B.; GLUCKSTERN, R.L.

    2005-05-15

    We determine the impedance of a cylindrical metal tube (resistor) of radius a, length g, and conductivity {sigma}, attached at each end to perfect conductors of semi-infinite length. Our main interest is in the asymptotic behavior of the impedance at high frequency, k >> 1/a. In the equilibrium regime, , the impedance per unit length is accurately described by the well-known result for an infinite length tube with conductivity {sigma}. In the transient regime, ka{sup 2} >> g, we derive analytic expressions for the impedance and wakefield.

  17. Transferring human impedance regulation skills to robots

    CERN Document Server

    Ajoudani, Arash

    2016-01-01

    This book introduces novel thinking and techniques to the control of robotic manipulation. In particular, the concept of teleimpedance control as an alternative method to bilateral force-reflecting teleoperation control for robotic manipulation is introduced. In teleimpedance control, a compound reference command is sent to the slave robot including both the desired motion trajectory and impedance profile, which are then realized by the remote controller. This concept forms a basis for the development of the controllers for a robotic arm, a dual-arm setup, a synergy-driven robotic hand, and a compliant exoskeleton for improved interaction performance.

  18. Analyzing Impedance Spectroscopy Results

    Institute of Scientific and Technical Information of China (English)

    Yoed Tsur; Sioma Baltianski

    2006-01-01

    In this contribution we briefly discuss several analysis techniques for impedance spectroscopy experiments. A number of different approaches, which differ even by the definition of the problem, are used in the literature. Some aimed towards finding an equivalent circuit. Others aimed towards finding directly dielectric properties of the material under an assumed model. Others towards finding distribution of relaxation times, either parametric or point-by point. No matter what the approach is, this will always be an ill-posed problem in the sense that there exist a large number of possible solutions that solve the problem (mathematically) equally well. Therefore some a-priori knowledge about the system must be used. In addition, we should remember that the ultimate goal is to get physical insight about the system.

  19. 机器人柔性抓取试验平台的设计与抓持力跟踪阻抗控制%Design of test platform for robot flexible grasping and grasping force tracking impedance control

    Institute of Scientific and Technical Information of China (English)

    王学林; 肖永飞; 毕淑慧; 范新建; 饶洪辉

    2015-01-01

    One of the major challenges of agricultural robots is the grasping and picking fresh fruit and vegetable without any damage under the complex environment. In order to minimize the harm due to robot grasp, this paper mainly introduces a dexterous multisensory gripper design and also develops a new force impedance control algorithm. First, the gripper with dual motor drive was designed, and each of fingers had an independent servo drive system and was integrated with force and tactile sensors. The calibration force sensors were mounted at the root of each finger, and the force signals were obtained by the force sensors. The expected force, position and speed parameters of the fingers can be set separately, so the grip centre and stroke can be controlled for the finger by pre-programming, the movement and forces of grasped objects can be actively controlled to achieve through the two-finger operations. The gripper with both the mechanical mechanism and control flexibility was mounted in the end of the industrial robot. The grasping experiment platform composed of industrial robot and dexterous gripper integrated monocular vision, force sensing and many kinds of sensors. The 2-D vision was able to quickly detect and locate grasped objects at the top of the experiment platform. Second, a force impedance control algorithm was proposed and used for one of fingers, position control was used for another finger, and it can regulate the grasping force by defining the target impedance between desired position and contact force. The whole grasping system can be equivalent to impedance&admittance model, and the finger force/position control can be equivalent to the expected target inertia-damping-stiffness model, and the model parameters can be adjustable according to the needs to realize the dynamic relationship between grasping force and position. The contact force errors between expected force value and actual force acquired from the force sensor were as the input of

  20. Short-circuit impedance measurement

    DEFF Research Database (Denmark)

    Pedersen, Knud Ole Helgesen; Nielsen, Arne Hejde; Poulsen, Niels Kjølstad

    2003-01-01

    Methods for estimating the short-circuit impedance in the power grid are investigated for various voltage levels and situations. The short-circuit impedance is measured, preferably from naturally occurring load changes in the grid, and it is shown that such a measurement system faces different...

  1. Impedance of Finite Length Resistor

    CERN Document Server

    Krinsky, Samuel; Podobedov, Boris

    2005-01-01

    We determine the impedance of a cylindrical metal tube (resistor) of radius a and length g, attached at each end to perfect conductors of semi-infinite length. Our main interest is in the behavior of the impedance at high frequency (k>>1/a). In the equilibrium regime, ka2

  2. Maximum Power Point Tracking Control in the Photovoltaic Power Generation Based on Dynamic Equivalent Impedance Matching Theory%基于动态等效阻抗匹配的光伏发电最大功率点跟踪控制

    Institute of Scientific and Technical Information of China (English)

    郑颖楠; 王俊平; 张霞

    2011-01-01

    A new method which can linearize the nonlinear internal impedance was proposed. Based on the concept of dynamic equivalent impedance error, the engineering significance of dynamic equivalent impedance matching and the validity of dynamic equivalent impedance error control method were discussed. According to the thought of equivalent impedance matching, the self-optimizing maximum power point tracking (MPPT) control structure and algorithm in the photovoltaic power generation were developed, which can be achieved by digital. The experimental results show that the dynamic equivalent impedance matching algorithm has more obvious advantages, compared with the classic MPPT control algorithms.%提出1种非线性内阻抗的线性化处理方法.基于动态等效阻抗误差的概念,论述动态等效阻抗适配的L程意义:阐述动态等效阻抗误差控制的有效性.根据等效阻抗适配思想,构造出数字实现的光伏发电最大功率点跟踪(maximum power point tracking,MPPT)自寻优控制系统结构和算法.最后的实验结果证明,与几种经典MPPT控制算法相比,动态等效阻抗匹配控制算法具有更明显的优点.

  3. Electrical impedance spectroscopy and diagnosis of tendinitis.

    Science.gov (United States)

    Yoon, Kisung; Lee, Kyeong Woo; Kim, Sang Beom; Han, Tai Ryoon; Jung, Dong Keun; Roh, Mee Sook; Lee, Jong Hwa

    2010-02-01

    There have been a number of studies that investigate the usefulness of bioelectric signals in diagnoses and treatment in the medical field. Tendinitis is a musculoskeletal disorder with a very high rate of occurrence. This study attempts to examine whether electrical impedance spectroscopy (EIS) can detect pathological changes in a tendon and find the exact location of the lesion. Experimental tendinitis was induced by injecting collagenase into one side of the patellar tendons in rabbits, while the other side was used as the control. After measuring the impedance in the tendinitis and intact tendon tissue, the dissipation factor was computed. The real component of impedance and the dissipation factor turned out to be lower in tendinitis than in intact tissues. Moreover, the tendinitis dissipation factor spectrum showed a clear difference from that of the intact tendon, indicating its usefulness as a tool for detecting the location of the lesion. Pathologic findings from the tissues that were obtained after measuring the impedance confirmed the presence of characteristics of tendinitis. In conclusion, EIS is a useful method for diagnosing tendinitis and detecting the lesion location in invasive treatment.

  4. Determination of beam coupling impedance in the frequency domain

    Energy Technology Data Exchange (ETDEWEB)

    Niedermayer, Uwe

    2016-07-01

    The concept of beam coupling impedance describes the electromagnetic interaction of uniformly moving charged particles with their surrounding structures in the Frequency Domain (FD). In synchrotron accelerators, beam coupling impedances can lead to beam induced component heating and coherent beam instabilities. Thus, in order to ensure the stable operation of a synchrotron, its impedances have to be quantified and their effects have to be controlled. Nowadays, beam coupling impedances are mostly obtained by Fourier transform of wake potentials, which are the results of Time Domain (TD) simulations. However, at low frequencies, low beam velocity, or for dispersive materials, TD simulations become unhandy. In this area, analytical calculations of beam coupling impedance in the FD, combined with geometry approximations, are still widely used. This thesis describes the development of two electromagnetic field solvers to obtain the beam coupling impedance directly in the FD, where the beam velocity is only a parameter and dispersive materials can be included easily. One solver is based on the Finite Integration Technique (FIT) on a staircase mesh. It is implemented both in 2D and 3D. However, the staircase mesh is inefficient on curved structures, which is particularly problematic for the modeling of a dipole source, that is required for the computation of the transverse beam coupling impedance. This issue is overcome by the second solver developed in this thesis, which is based on the Finite Element Method (FEM) on an unstructured triangular mesh. It is implemented in 2D and includes an optional Surface Impedance Boundary Condition (SIBC). Thus, it is well suited for the computation of longitudinal and transverse impedances of long beam pipe structures of arbitrary cross-section. Besides arbitrary frequency and beam velocity, also dispersive materials can be chosen, which is crucial for the computation of the impedance of ferrite kicker magnets. Numerical impedance

  5. Virtual Impedance Based Stability Improvement for DC Microgrids with Constant Power Loads

    DEFF Research Database (Denmark)

    Lu, Xiaonan; Sun, Kai; Huang, Lipei

    2014-01-01

    . To validate the stability with the above stabilizers in a DC microgrid with parallel interfacing converters and CPL, the impedance matching approach is employed. The output impedance of the source converter and input impedance of the load are calculated respectively, and the influence of droop control...

  6. 基于能量转换的仿人机器人摆动腿落地改进阻抗控制方法%Improved impedance control of humanoid robot swing leg landing based on energy conversion

    Institute of Scientific and Technical Information of China (English)

    常琦; 张国良; 敬斌

    2012-01-01

    According to no buffering device of biped humanoid robot in the rapid movement of swing leg landing will affect the stability of the robot body problems, combined with the impedance control characteristics, analyzed from the perspective of energy conversion based on energy conversion of the humanoid robot leg landing, an improved impedance control method was proposed. Based on the impedance control method as the foundation, through analysis with the robot leg swing fall terminal velocity and barycenter velocity after landing, combined with the energy conversion in the swing leg landing process, the authors controlled the force of robot leg when landing, achieved the purpose that the swing leg landing buffered. Finally, this method was applied to robot Nao. The experiment proves that the instantaneous force is decreased when robot leg swing landing ground, achieves the effect of buffer landing, and the pre-control was implemented.%针对没有缓冲装置的双足仿人机器人在快速运动中摆动腿落地会对机器人身体稳定性带来影响的问题,结合阻抗控制的控制特点,从能量转换的角度进行分析,提出了基于能量转换的仿人机器人摆动腿落地改进阻抗控制方法.以阻抗控制方法为基础,通过对机器人摆动腿落地时末端速度以及落地后质心速度的分析,结合在摆动腿落地这一过程中能量的转换关系,对机器人摆动腿各关节的力进行控制,从而达到机器人摆动腿缓冲落地的目的.最后,将此方法应用于机器人Nao,实验证明,机器人摆动腿落地时与地面的瞬时作用力减小,达到了缓冲落地的效果,同时也起到了预先控制的作用.

  7. Geometric beam coupling impedance of LHC secondary collimators

    Energy Technology Data Exchange (ETDEWEB)

    Frasciello, Oscar, E-mail: oscar.frasciello@lnf.infn.it [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Frascati, Via Enrico Fermi 40, 00044 Frascati (Italy); Tomassini, Sandro; Zobov, Mikhail [Istituto Nazionale di Fisica Nucleare - Laboratori Nazionali di Frascati, Via Enrico Fermi 40, 00044 Frascati (Italy); Salvant, Benoit; Grudiev, Alexej; Mounet, Nicolas [CERN, CH-1211 Geneva 23 (Switzerland)

    2016-02-21

    The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep beam instabilities under control and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are among the major impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were higher by about a factor of 2 with respect to the theoretical predictions based on the LHC impedance model up to 2012. In that model the resistive wall impedance has been considered as the dominating impedance contribution for collimators. By carefully simulating also their geometric impedance we have contributed to the update of the LHC impedance model, reaching also a better agreement between the measured and simulated betatron tune shifts. During the just ended LHC Long Shutdown I (LSI), TCS/TCT collimators were replaced by new devices embedding BPMs and TT2-111R ferrite blocks. We present here preliminary estimations of their broad-band impedance, showing that an increase of about 20% is expected in the kick factors with respect to previous collimators without BPMs.

  8. Kinetics of electrochemically controlled surface reactions on bulk and thin film metals studied with Fourier transform impedance spectroscopy and surface plasmon resonance techniques

    Science.gov (United States)

    Assiongbon, Kankoe A.

    2005-07-01

    In the work presented in this thesis, the surface sensitive electrochemical techniques of cyclic voltametry (CV), potential step (PS) and Fourier transform impedance spectroscopy (FT-EIS), as well as the optical technique of surface plasmon resonance (SPR), were used to probe a wide variety of surface processes at various metal/liquid interface. Three polycrystalline metals (Au, Ta and Cu) and a Cr-coated gold film were used for these studies in different aqueous environments. A combination of CV with FT-EIS and PS was used to investigate electronic and structural proprieties of a modified bulk electrode of Au. This experimental system involved under potential deposition (UPD) of Bi3+ on Au in a supporting aqueous electrolyte containing ClO-4 . UPD range of Bi3+ was determined, and adsorption kinetics of Bi3+ in the presence of coadsorbing anion, ClO-4 were quantified. Potentiodynamic growth of oxide films of Ta in the following electrolytes NaNO3, NaNO3 + 5wt% H2O2, NaOH and NaOH + 5wt% H2O2 had been investigated. The oxide films were grown in the range -0.1 → +0.4V (high electric field) at a scan rate of 10 mV/s. Time resolved A.C. impedance spectroscopy measurements in the frequency range (0.1--20 KHz) were performed to characterize the surface reactions of oxide formation. The results are interpreted in terms of charge conductivity O2- through the oxide film, and disintegration of H2O2 into OH-. In a high pH medium (pH 12), dissociation of H2O2 was catalytically enhanced. This led to destabilization of the electrogenerated tantalum oxide surface film in the form of a soluble hexatantalate species. In contrast with the electrolytes, NaNO3, NaNO3 + 5wt% H2O2, NaOH, where only the oxide growth was observed, the A.C. impedance spectroscopy measurements in NaOH + 5wt% H 2O2 showed competition between oxide formation and its removal. These results are relevant for chemical slurry design in chemical mechanical polishing (CMP) of Ta. Further investigations were

  9. Impedance-estimation methods, modeling methods, articles of manufacture, impedance-modeling devices, and estimated-impedance monitoring systems

    Science.gov (United States)

    Richardson, John G.

    2009-11-17

    An impedance estimation method includes measuring three or more impedances of an object having a periphery using three or more probes coupled to the periphery. The three or more impedance measurements are made at a first frequency. Three or more additional impedance measurements of the object are made using the three or more probes. The three or more additional impedance measurements are made at a second frequency different from the first frequency. An impedance of the object at a point within the periphery is estimated based on the impedance measurements and the additional impedance measurements.

  10. Scattering patterns of dihedral corner reflectors with impedance surface impedances

    Science.gov (United States)

    Balanis, Constantine A.; Griesser, Timothy; Liu, Kefeng

    The radar cross section patterns of lossy dihedral corner reflectors are calculated using a uniform geometrical theory of diffraction for impedance surfaces. All terms of up to third order reflections are considered for patterns in the principal plane. The surface waves are included whenever they exist for reactive surface impedances. The dihedral corner reflectors examined have right, obtuse, and acute interior angles, and patterns over the entire 360 deg azimuthal plane are calculated. The surface impedances can be different on the four faces of the dihedral corner reflector; however, the surface impedance must be uniform over each face. Computed cross sections are compared with a moment method technique for a dielectric/ferrite absorber coating on a metallic corner reflector. The analysis of the dihedral corner reflector is important because it demonstrates many of the important scattering contributors of complex targets including both interior and exterior wedge diffraction, half-plane diffraction, and dominant multiple reflections and diffractions.

  11. GB-R impedances: new approach to impedance simulation

    Science.gov (United States)

    Serrano, L.; Carlosena, A.

    1995-04-01

    A new design procedure is presented for obtaining simulated inductors and large capacitors from classical opamp circuits. Such impedances exploit almost all of the available bandwidth of the operational amplifier.

  12. HDR reservoir flow impedance and potentials for impedance reduction

    Energy Technology Data Exchange (ETDEWEB)

    DuTeau, R.; Brown, D.

    1993-06-01

    The data from flow tests which employed two different production zones in a well at Fenton Hill indicates the flow impedance of a wellbore zone damaged by rapid depressurization was altered, possibly by pressure spallation, which appears to have mechanically propped the joint apertures of outlet flow paths intersecting the altered wellbore. The rapid depressurization and subsequent flow test data derived from the damaged well has led to the hypothesis that pressure spallation and the resultant mechanical propping of outlet flow paths reduced the outlet flow impedance of the damaged wellbore. Furthermore, transient pressure data shows the largest pressure drop between the injection and production wellheads occurs near the production wellbore, so lowering the outlet impedance by increasing the apertures of outlet flow paths will have the greatest effect on reducing the overall reservoir impedance. Fenton Hill data also reveals that increasing the overall reservoir pressure dilates the apertures of flow paths, which likewise serves to reduce the reservoir impedance. Data suggests that either pressure dilating the wellbore connected joints with high production wellhead pressure, or mechanically propping open the outlet flow paths will increase the near-wellbore permeability. Finally, a new method for calculating and comparing near-wellbore outlet impedances has been developed. Further modeling, experimentation, and engineered reservoir modifications, such as pressure dilation and mechanical propping, hold considerable potential for significantly improving the productivity of HDR reservoirs.

  13. 一种对机器人阻抗控制中不确定性进行补偿的方法%Method to Compensate Uncertainties in Robot Impedance Control

    Institute of Scientific and Technical Information of China (English)

    王宇驰; 陈友东; 游玮

    2016-01-01

    The uncertainties existing in robot models present difficulties to controlling robots precisely. This is especially obvious in robot force control, and limits the usage of robot force control in industry field. Intelligent control, such as fuzzy control and neural network, is an effective method to solve this problem faced by classical control methods. Unsupervised learning network was adopted to compensate the uncertainties existing in robot impedance control online and to improve the performance of force tracking. The effective-ness of the proposed neural algorithm is verified by a simulation.%机器人建模中存在的不确定性,给机器人精确控制带来了困难,在机器人力控制中尤为明显,制约了力控制在实际生产中的应用.采用模糊控制、 神经网络等智能控制方法是解决这些经典控制理论所面临问题的有效手段.文中使用无监督学习的神经网络对不确定性进行在线补偿,提高阻抗控制的力跟踪性能,通过仿真验证了算法的有效性.

  14. Development on electromagnetic impedance function modeling and its estimation

    Energy Technology Data Exchange (ETDEWEB)

    Sutarno, D., E-mail: Sutarno@fi.itb.ac.id [Earth Physics and Complex System Division Faculty of Mathematics and Natural Sciences Institut Teknologi Bandung (Indonesia)

    2015-09-30

    Today the Electromagnetic methods such as magnetotellurics (MT) and controlled sources audio MT (CSAMT) is used in a broad variety of applications. Its usefulness in poor seismic areas and its negligible environmental impact are integral parts of effective exploration at minimum cost. As exploration was forced into more difficult areas, the importance of MT and CSAMT, in conjunction with other techniques, has tended to grow continuously. However, there are obviously important and difficult problems remaining to be solved concerning our ability to collect process and interpret MT as well as CSAMT in complex 3D structural environments. This talk aim at reviewing and discussing the recent development on MT as well as CSAMT impedance functions modeling, and also some improvements on estimation procedures for the corresponding impedance functions. In MT impedance modeling, research efforts focus on developing numerical method for computing the impedance functions of three dimensionally (3-D) earth resistivity models. On that reason, 3-D finite elements numerical modeling for the impedances is developed based on edge element method. Whereas, in the CSAMT case, the efforts were focused to accomplish the non-plane wave problem in the corresponding impedance functions. Concerning estimation of MT and CSAMT impedance functions, researches were focused on improving quality of the estimates. On that objective, non-linear regression approach based on the robust M-estimators and the Hilbert transform operating on the causal transfer functions, were used to dealing with outliers (abnormal data) which are frequently superimposed on a normal ambient MT as well as CSAMT noise fields. As validated, the proposed MT impedance modeling method gives acceptable results for standard three dimensional resistivity models. Whilst, the full solution based modeling that accommodate the non-plane wave effect for CSAMT impedances is applied for all measurement zones, including near-, transition

  15. IMPEDANCE CHARACTERISTICS OF POLYFURAN FILMS

    Institute of Scientific and Technical Information of China (English)

    Liang Li; Xiao-bo Wan; Gi Xue

    2002-01-01

    Electrochemical impedance spectroscopy (EIS) was first used for the characterization of polyfuran (PFu) films that had been formed electrochemically on an Au electrode. The polyfuran was measured in high oxidation state, intermediate oxidation state and reduction state, respectively. As the oxidation level is increased, the ionic conductivity of PFu/BF4-increases. And impedance studies on PFu show that the anion BF4- appears to be mobile with a high diffusion coefficient of approximately 10-8 cm2 @ s-1.

  16. Frequency Control Loop for Drift Tube Linac

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyeok Jung; Kim, Han Sung; Seol, Kyung Tae; Song, Young Gi; Jang, Ji Ho; Cho, Yong Sub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-10-15

    In this paper, the preparation of the frequency tracking of the RCCS by connecting the RCCS to low level RF (LLRF) system is described. KOMAC 100-MeV proton accelerator is under operation and supply beam to users. We are developing frequency control function in the LLRF system to control the RCCS in frequency control mode. After the test in the test bench, the system will be applied to the 100-MeV DTL RCCS in order to supply better quality beam to users. A 100-MeV proton accelerator has been developed and the operation and beam service started at Korea Multipurpose Accelerator Complex (KOMAC) in June 2013. The accelerator consists of a 50-keV proton injector, a 3-MeV radio frequency quadrupole (RFQ) and 100-MeV drift tube linac (DTL). The resonance frequency of the DTL tanks are controlled by using the resonance frequency control cooling system (RCCS), which are installed at every each tank. Until now, the RCCS has been operating in constant temperature mode which means that the frequency was measured with respect to the RCCS supply temperature before the RF operation, and then the RCCS operates with that temperature throughout the whole operation. The constant temperature operation is simple but the RF stability is not good because many perturbations such as RCCS supply temperature error can cause a frequency change. To stabilize the system better, it is necessary to operate the RCCS in frequency tracking mode.

  17. Geometric Beam Coupling Impedance of LHC Secondary Collimators

    CERN Document Server

    Frasciello, O; Zobov, M; Grudiev, A; Mounet, N; Salvant, B

    2014-01-01

    The High Luminosity LHC project is aimed at increasing the LHC luminosity by an order of magnitude. One of the key ingredients to achieve the luminosity goal is the beam intensity increase. In order to keep under control beam instabilities and to avoid excessive power losses a careful design of new vacuum chamber components and an improvement of the present LHC impedance model are required. Collimators are the main impedance contributors. Measurements with beam have revealed that the betatron coherent tune shifts were by about a factor of 2 higher with respect to the theoretical predictions based on the current model. Up to now the resistive wall impedance has been considered as the major impedance contribution for collimators. By carefully simulating their geometric impedance we show that for the graphite collimators with half-gaps higher than 10 mm the geometric impedance exceeds the resistive wall one. In turn, for the tungsten collimators the geometric impedance dominates for all used gap values. Hence, i...

  18. Impedance spectroscopy for the detection and identification of unknown toxins

    Science.gov (United States)

    Riggs, B. C.; Plopper, G. E.; Paluh, J. L.; Phamduy, T. B.; Corr, D. T.; Chrisey, D. B.

    2012-06-01

    Advancements in biological and chemical warfare has allowed for the creation of novel toxins necessitating a universal, real-time sensor. We have used a function-based biosensor employing impedance spectroscopy using a low current density AC signal over a range of frequencies (62.5 Hz-64 kHz) to measure the electrical impedance of a confluent epithelial cell monolayer at 120 sec intervals. Madin Darby canine kidney (MDCK) epithelial cells were grown to confluence on thin film interdigitated gold electrodes. A stable impedance measurement of 2200 Ω was found after 24 hrs of growth. After exposure to cytotoxins anthrax lethal toxin and etoposide, the impedance decreased in a linear fashion resulting in a 50% drop in impedance over 50hrs showing significant difference from the control sample (~20% decrease). Immunofluorescent imaging showed that apoptosis was induced through the addition of toxins. Similarities of the impedance signal shows that the mechanism of cellular death was the same between ALT and etoposide. A revised equivalent circuit model was employed in order to quantify morphological changes in the cell monolayer such as tight junction integrity and cell surface area coverage. This model showed a faster response to cytotoxin (2 hrs) compared to raw measurements (20 hrs). We demonstrate that herein that impedance spectroscopy of epithelial monolayers serves as a real-time non-destructive sensor for unknown pathogens.

  19. Probing the LHC impedance with single bunches

    CERN Document Server

    Esteban Müller, J F; Bohl, T; Bhat, C; Calaga, R; Kain, V; Kuhn, M; Mounet, N; Papotti, G; Shaposhnikova, E; Timko, H

    2013-01-01

    The main purpose of this MD was to study longitudinal and transverse beam dynamics in the LHC. Eight bunches with different bunch lengths and intensities were injected into the LHC in two fills. The distance between bunches is large enough so they can be treated as single bunches. The bunch length and the intensity were adjusted in the SPS by applying controlled longitudinal emittance blow-up with different amplitudes and transverse scraping. The aim of the first fill was to measure the longitudinal and the transverse impedance at injection energy (450 GeV). The second fill of the MD included acceleration to 4 TeV and was used to study the loss of Landau damping during the ramp, observed as dipole and quadrupole oscillations, and to measure the impedance at top energy. Measurements of synchronous phase shift and peak-detected Schottky spectra were taken during both fills in order to estimate the longitudinal impedance and they are presented in this Note. We also show the transverse emittance evolution during ...

  20. Report of the SSC impedance workshop

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1985-10-28

    This workshop focused attention on the transverse, single-bunch instability and the detailed analysis of the broadband impedance which would drive it. Issues discussed included: (1) single bunch stability -- impact of impedance frequency shape, coupled-mode vs. fast blowup regimes, possible stopband structure; (2) numerical estimates of transverse impedance of inner bellows and sliding contact shielded bellows; (3) analytic estimates of pickup and kicker impedance contributions; and (4) feasibility studies of wire and beam measurements of component impedance.

  1. Experimental verification of the feasibility of the cardiovascular impedance simulator.

    Science.gov (United States)

    Gwak, Kwan-Woong; Paden, Brad E; Antaki, James F; Ahn, Ihn-Seok

    2010-05-01

    Mock circulatory systems (MCS) are often used for the development of cardiovascular devices and for the study of the dynamics of blood flow through the cardiovascular system. However, conventional MCS suffer from the repeatability, flexibility, and precision problems because they are typically built up with passive and linear fluidic elements such as compliance chamber, manual valve, and tube. To solve these limitations, we have developed an impedance simulator, comprised of a feedback-controlled positive displacement pump that is capable of generating analogous dynamic characteristics as the conventional fluidic elements would generate, thereby replacing the conventional passive fluidic elements that often cause problems. The impedance simulator is experimentally proven to reproduce the impedance of the various discrete elements, such as resistance and compliance of the cardiovascular system model, as well as the combined impedances of them.

  2. Bioelectrical impedance analysis for bovine milk: Preliminary results

    Science.gov (United States)

    Bertemes-Filho, P.; Valicheski, R.; Pereira, R. M.; Paterno, A. S.

    2010-04-01

    This work reports the investigation and analysis of bovine milk quality by using biological impedance measurements using electrical impedance spectroscopy (EIS). The samples were distinguished by a first chemical analysis using Fourier transform midinfrared spectroscopy (FTIR) and flow citometry. A set of milk samples (100ml each) obtained from 17 different cows in lactation with and without mastitis were analyzed with the proposed technique using EIS. The samples were adulterated by adding distilled water and hydrogen peroxide in a controlled manner. FTIR spectroscopy and flow cytometry were performed, and impedance measurements were made in a frequency range from 500Hz up to 1MHz with an implemented EIS system. The system's phase shift was compensated by measuring saline solutions. It was possible to show that the results obtained with the Bioelectrical Impedance Analysis (BIA) technique may detect changes in the milk caused by mastitis and the presence of water and hydrogen peroxide in the bovine milk.

  3. Measurement of Phase Dependent Impedance for 3-phase Diode Rectifier

    DEFF Research Database (Denmark)

    Kwon, Jun Bum; Wang, Xiongfei; Bak, Claus Leth

    2016-01-01

    This paper presents a new method to measure the phase dependent impedance from an experimental set up. Though most of power electronics based system is gradually migrating to IGBT based voltage source converter due to their controllability, the rectifier composed of diode or thyristor components...... are still widely used in AC-DC applications because of their cost effectiveness and reliability. However, these topologies generate harmonic problems in their network due to their switching instant variation caused by the frequency and phase of grid voltage. Hence, a lot of solutions have been proposed...... application. It is found that the phase dependent impedance shows different properties with the impedance profiles, which have been proposed in the research. This paper explains a method to measure the phase dependent impedance profile from an experimental set up. Furthermore, the results are compared...

  4. Definition of the characteristic impedance

    Institute of Scientific and Technical Information of China (English)

    徐云生; Abbas Sayed OMAR

    1996-01-01

    Currently available definitions of the characteristic impedance are ambiguous andior inaccurate.A general definition,based on the description of discontinuities between adjacent waveguides,is given.This definition is accurate and independent of the structure concerned.So it can be applied to the design of passive components in any type of transmission lines.Using this definition,a given structure can be uniquely characterized,but the absolute value of the characteristic impedance has no sense any more.As an example,the design of a microstrip impedance transformer using this new definition is presented.Numerical results using the mode-matching method prove the accuracy of the theory.

  5. Transverse Impedance of LHC Collimators

    CERN Document Server

    Métral, E; Assmann, Ralph Wolfgang; Boccardi, A; Bracco, C; Bohl, T; Caspers, Friedhelm; Gasior, M; Jones, O R; Kasinski, K; Kroyer, T; Redaelli, S; Robert-Demolaize, R; Roncarolo, F; Rumolo, G; Salvant, B; Steinhagen, R; Weiler, T; Zimmermann, F

    2007-01-01

    The transverse impedance in the LHC is expected to be dominated by the numerous collimators, most of which are made of Fibre-Reinforced-Carbon to withstand the impacts of high intensity proton beams in case of failures, and which will be moved very close to the beam, with full gaps of few millimetres, in order to protect surrounding super-conducting equipments. We present an estimate of the transverse resistive-wall impedance of the LHC collimators, the total impedance in the LHC at injection and top energy, the induced coupled-bunch growth rates and tune shifts, and finally the result of the comparison of the theoretical predictions with measurements performed in 2004 and 2006 on a prototype collimator installed in the SPS.

  6. Impedances of Laminated Vacuum Chambers

    Energy Technology Data Exchange (ETDEWEB)

    Burov, A.; Lebedev, V.; /Fermilab

    2011-06-22

    First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].

  7. Hybrid-Source Impedance Networks

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang;

    2010-01-01

    the cascaded networks would have a higher output voltage gain and other unique advantages that currently have not been investigated yet. It is anticipated that these advantages would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually......Hybrid-source impedance networks have attracted attention among researchers because of their flexibility in performing buck-boost energy conversion. To date, three distinct types of impedance networks can be summarized for implementing voltage-type inverters with another three types summarized...

  8. Y-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Loh, Poh Chiang; Blaabjerg, Frede;

    2014-01-01

    This letter introduces a new versatile Y-shaped impedance network for realizing converters that demand a very high-voltage gain, while using a small duty ratio. To achieve that, the proposed network uses a tightly coupled transformer with three windings, whose obtained gain is presently not matched...... by existing networks operated at the same duty ratio. The proposed impedance network also has more degrees of freedom for varying its gain, and hence, more design freedom for meeting requirements demanded from it. This capability has been demonstrated by mathematical derivation, and proven in experiment...

  9. Microfabricated Thin Film Impedance Sensor & AC Impedance Measurements

    Directory of Open Access Journals (Sweden)

    Jinsong Yu

    2010-06-01

    Full Text Available Thin film microfabrication technique was employed to fabricate a platinum based parallel-electrode structured impedance sensor. Electrochemical impedance spectroscopy (EIS and equivalent circuit analysis of the small amplitude (±5 mV AC impedance measurements (frequency range: 1 MHz to 0.1 Hz at ambient temperature were carried out. Testing media include 0.001 M, 0.01 M, 0.1 M NaCl and KCl solutions, and alumina (~3 μm and sand (~300 μm particulate layers saturated with NaCl solutions with the thicknesses ranging from 0.6 mm to 8 mm in a testing cell, and the results were used to assess the effect of the thickness of the particulate layer on the conductivity of the testing solution. The calculated resistances were approximately around 20 MΩ, 4 MΩ, and 0.5 MΩ for 0.001 M, 0.01 M, and 0.1 M NaCl solutions, respectively. The presence of the sand particulates increased the impedance dramatically (6 times and 3 times for 0.001 M and 0.1 M NaCl solutions, respectively. A cell constant methodology was also developed to assess the measurement of the bulk conductivity of the electrolyte solution. The cell constant ranged from 1.2 to 0.8 and it decreased with the increase of the solution thickness.

  10. Input impedance characteristics of microstrip structures

    Directory of Open Access Journals (Sweden)

    A. I. Nazarko

    2015-06-01

    Full Text Available Introduction. Electromagnetic crystals (EC and EC-inhomogeneities are one of the main directions of microstrip devices development. In the article the input impedance characteristics of EC- and traditional microstrip inhomogeneities and filter based on EC-inhomogeneities are investigated. Transmission coefficient characteristics. Transmission coefficient characteristics of low impedance EC- and traditional inhomogeneities are considered. Characteristics are calculated in the software package Microwave Studio. It is shown that the efficiency of EC-inhomogeneity is much higher. Input impedance characteristics of low impedance inhomogeneities. Dependences of input impedance active and reactive parts of EC- and traditional inhomogeneities are given. Dependences of the active part illustrate significant low impedance transformation of nominal impedance. The conditions of impedance matching of structure and input medium are set. Input impedance characteristics of high impedance inhomogeneities. Input impedance characteristics of high impedance EC- and traditional inhomogeneities are considered. It was shown that the band of transformation by high impedance inhomogeneities is much narrower than one by low impedance inhomogeneities. Characteristics of the reflection coefficient of inhomogeneities are presented. Input impedance characteristics of narrowband filter. The structure of narrowband filter based on the scheme of Fabry-Perot resonator is presented. The structure of the filter is fulfilled by high impedance EC-inhomogeneities as a reflectors. Experimental and theoretical amplitude-frequency characteristics of the filter are presented. Input impedance characteristics of the filter are shown. Conclusions. Input impedance characteristics of the structure allow to analyse its wave properties, especially resonant. EC-inhomogeneity compared with traditional microstrip provide substantially more significant transformation of the the input impedance.

  11. Operating Unknown Constrained Mechanisms Based on Motion Prediction and Impedance Control%基于运动预测和阻抗控制的未知受限机构操作

    Institute of Scientific and Technical Information of China (English)

    孙逸翔; 陈卫东

    2011-01-01

    针对服务机械臂操作各种未知受限运动机构的需要,提出了一种基于运动预测和阻抗控制的控制方法,本方法采用试探一预测一修正的滚动操作策略,通过阻抗控制保证机械臂与未知受限机构交互的柔性.首先试探受限机构的运动能力,根据已有操作臂运动轨迹估计受限机构的运动模型,然后预测受限机构的运动方向,进而修正机械臂的运动轨迹,并根据交互作用强度动态调节运动速率.基于上述连续滚动调节,提高了机械臂对未知受限机构操作的安全性和效率.配置6维腕力/力矩传感器的6自由度辅助机械臂的开门实验,证明了所提方法的有效性.%In order to meet the needs for assistive robot manipulators in operating various constrained mechanisms, a con-trol method based on motion prediction and impedance control is proposed. A rolling manipulation strategy of exploration-prediction-adjustment is employed, through impedance control to provide compliant interaction between the assistive manip-ulator and unknown constrained mechanisms. Firstly, the motion capability of the constrained mechanism is explored to build its motion model according to the passed motion trajectory of the manipulator. Then, motion direction of the mechanism is predicted based on the motion model. Finally, the trajectory of manipulator is adjusted in alignment with the predicted direc-tion, while the magnitude of the velocity is dynamically adjusted according to the interaction force. Based on this continuous rolling adjustment, safety and efficiency of a manipulator for operating unknown constrained mechanisms are enhanced. Ex-periments of autonomous door opening utilizing a 6D0F assistive manipulator with a six-dimensional force/torque sensor demonstrate the validity of the proposed method.

  12. Grid impedance detection via excitation of LCL-filter resonance

    DEFF Research Database (Denmark)

    Liserre, Marco; Blaabjerg, Frede; Teodorescu, Remus

    2005-01-01

    the resonance of the LCL-fiIter can be also excited in a controlled way in order to individuate the resonance frequency in the spectrum (using for example the FFn. This paper proposes to use a controlled excitation to measure the grid impedance, since this one influences also the resonance frequency. This paper...... will address some possible limits, some solutions and some implementation issues (e.g. how to obtain a controlled resonance in the filter without damaging the system) in order to use the resonant peak for grid impedance detection. The analysis is validated both by simulations and experimental results....

  13. Advances in Impedance Controlled Endometrial Resection System for Abnormal Uterine Bleeding%阻抗控制子宫内膜切除系统治疗异常子宫出血的新进展

    Institute of Scientific and Technical Information of China (English)

    谭慧珍

    2013-01-01

    阻抗控制子宫内膜切除系统属于第二代子宫内膜去除术,在治疗异常子宫出血(AUB)中,通过射频能量切除子宫内膜以达到控制月经过多的目的,具有操作简便、内膜破坏深度一致、手术时间短、安全性高、创伤性小、并发症少和疗效显著的优点,越来越多地受到广大临床医师和患者的认同.该文就阻抗控制子宫内膜切除系统治疗AUB的临床应用进展予以综述.%NovaSure impedance control system has been established as a safe and effective second-generation technique for the treatment of abnormal uterine bleeding by endometrial resection. It resects endometrial and controls abnormal uterine bleeding by RF energy. It has a lot of advantages such as simple intimal,damage consistent depth, shorter operative time,high safety,less traumatic,fewer complications, significant efficacy and so on. It becomes welcomed by more and more clinicians and patients home and abroad. Here is to make a review of the new progress of NovaSure system for abnormal uterine bleeding.

  14. Acoustic Ground-Impedance Meter

    Science.gov (United States)

    Zuckerwar, A. J.

    1983-01-01

    Helmoltz resonator used in compact, portable meter measures acoustic impedance of ground or other surfaces. Earth's surface is subject of increasing acoustical investigations because of its importance in aircraft noise prediction and measurment. Meter offers several advantages. Is compact and portable and set up at any test site, irrespective of landscape features, weather or other environmental condition.

  15. Small Signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2014-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterized by the mechanical resonance between the mass of the diaphragm and the compliance of its suspension which vary...

  16. A randomized controlled trial of interventions to impede date palm sap contamination by bats to prevent nipah virus transmission in Bangladesh.

    Directory of Open Access Journals (Sweden)

    Salah Uddin Khan

    Full Text Available BACKGROUND: Drinking raw date palm sap is a risk factor for human Nipah virus (NiV infection. Fruit bats, the natural reservoir of NiV, commonly contaminate raw sap with saliva by licking date palm's sap producing surface. We evaluated four types of physical barriers that may prevent bats from contacting sap. METHODS: During 2009, we used a crossover design and randomly selected 20 date palm sap producing trees and observed each tree for 2 nights: one night with a bamboo skirt intervention applied and one night without the intervention. During 2010, we selected 120 trees and randomly assigned four types of interventions to 15 trees each: bamboo, dhoincha (local plant, jute stick and polythene skirts covering the shaved part, sap stream, tap and collection pot. We enrolled the remaining 60 trees as controls. We used motion sensor activated infrared cameras to examine bat contact with sap. RESULTS: During 2009 bats contacted date palm sap in 85% of observation nights when no intervention was used compared with 35% of nights when the intervention was used [p<0.001]. Bats were able to contact the sap when the skirt did not entirely cover the sap producing surface. Therefore, in 2010 we requested the sap harvesters to use larger skirts. During 2010 bats contacted date palm sap [2% vs. 83%, p<0.001] less frequently in trees protected with skirts compared to control trees. No bats contacted sap in trees with bamboo (p<0.001 compared to control, dhoincha skirt (p<0.001 or polythene covering (p<0.001, but bats did contact sap during one night (7% with the jute stick skirt (p<0.001. CONCLUSION: Bamboo, dhoincha, jute stick and polythene skirts covering the sap producing areas of a tree effectively prevented bat-sap contact. Community interventions should promote applying these skirts to prevent occasional Nipah spillovers to human.

  17. The Impedance Characteristic of Thyristor-controlled Series Capacitor with Resistance%具有电阻的TCSC阻抗特性

    Institute of Scientific and Technical Information of China (English)

    高明; 王洪波; 郑忠安; 李占清

    2002-01-01

    TCSC(Thyristor Controlled Series Capacitor)补偿装置具有灵活控制传输线中的功率流、改进系统的稳定性、提高传输能力等优点,提出一种考虑电阻的TCSC等效阻抗的计算方法,并用这种方法分析了TCSC的阻抗特性,对TCSC的实际应用具有指导意义.

  18. A non-IQ sampling controller in low level RF system

    Institute of Scientific and Technical Information of China (English)

    YIN Cheng-Ke; DAI Zhi-Min; LIU Jian-Fei; ZHAO Yu-Bin; ZHANG Tong-Xuan; FU Ze-Chuan; LIU Wei-Qing

    2008-01-01

    This paper describes a non-IQ controller for digital Low Level RF (LLRF) feedback control.Based on this non-IQ sarnpling method,arbitrary frequency relationship between ADC/DAC sampling clocks and IF signals can be employed.The nonlinearity in digital conversion can be reduced and the system dynamic performance improved.This paper analyzes the nonlinearity in conventional IQ sampling,gives the state variable description of the non-IQ algorithm,presents an implementation and its synchronization,and compares its performances with IQ sampling.

  19. A Unified Impedance Model of Grid-Connected Voltage-Source Converters

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

    2017-01-01

    This paper proposes a unified impedance model of grid-connected voltage-source converters for analyzing dynamic influences of the Phase-Locked Loop (PLL) and current control. The mathematical relations between the impedance models in the different domains are first explicitly revealed by means...... of complex transfer functions and complex space vectors. A stationary (αβ-) frame impedance model is then proposed, which not only predicts the stability impact of the PLL, but reveals also its frequency coupling effect explicitly. Furthermore, the impedance shaping effect of the PLL on the current control...

  20. Wideband impedance spectrum analyzer for process automation applications

    Science.gov (United States)

    Doerner, Steffen; Schneider, Thomas; Hauptmann, Peter R.

    2007-10-01

    For decades impedance spectroscopy is used in technical laboratories and research departments to investigate effects or material characteristics that affect the impedance spectrum of the sensor. Establishing this analytical approach for process automation and stand-alone applications will deliver additional and valuable information beside traditional measurement techniques such as the measurement of temperature, flow rate, and conductivity, among others. As yet, most of the current impedance analysis methods are suited for laboratory applications only since they involve stand-alone network analyzers that are slow, expensive, large, or immobile. Furthermore, those systems offer a large range of functionality that is not being used in process control and other fields of application. We developed a sensor interface based on high speed direct digital signal processing offering wideband impedance spectrum analysis with high resolution for frequency adjustment, excellent noise rejection, very high measurement rate, and convenient data exchange to common interfaces. The electronics has been implemented on two small circuit boards and it is well suited for process control applications such as monitoring phase transitions, characterization of fluidal systems, and control of biological processes. The impedance spectrum analyzer can be customized easily for different measurement applications by adapting the appropriate sensor module. It has been tested for industrial applications, e.g., dielectric spectroscopy and high temperature gas analysis.

  1. A Randomized Controlled Trial of Interventions to Impede Date Palm Sap Contamination by Bats to Prevent Nipah Virus Transmission in Bangladesh

    Science.gov (United States)

    Khan, Salah Uddin; Gurley, Emily S.; Hossain, M. Jahangir; Nahar, Nazmun; Sharker, M. A. Yushuf; Luby, Stephen P.

    2012-01-01

    Background Drinking raw date palm sap is a risk factor for human Nipah virus (NiV) infection. Fruit bats, the natural reservoir of NiV, commonly contaminate raw sap with saliva by licking date palm’s sap producing surface. We evaluated four types of physical barriers that may prevent bats from contacting sap. Methods During 2009, we used a crossover design and randomly selected 20 date palm sap producing trees and observed each tree for 2 nights: one night with a bamboo skirt intervention applied and one night without the intervention. During 2010, we selected 120 trees and randomly assigned four types of interventions to 15 trees each: bamboo, dhoincha (local plant), jute stick and polythene skirts covering the shaved part, sap stream, tap and collection pot. We enrolled the remaining 60 trees as controls. We used motion sensor activated infrared cameras to examine bat contact with sap. Results During 2009 bats contacted date palm sap in 85% of observation nights when no intervention was used compared with 35% of nights when the intervention was used [psap when the skirt did not entirely cover the sap producing surface. Therefore, in 2010 we requested the sap harvesters to use larger skirts. During 2010 bats contacted date palm sap [2% vs. 83%, psap in trees with bamboo (psap during one night (7%) with the jute stick skirt (psap producing areas of a tree effectively prevented bat-sap contact. Community interventions should promote applying these skirts to prevent occasional Nipah spillovers to human. PMID:22905160

  2. Beam Coupling Impedances of Small Discontinuities

    CERN Document Server

    Kurennoy, S S

    2000-01-01

    A general derivation of the beam coupling impedances produced by small discontinuities on the wall of the vacuum chamber of an accelerator is reviewed. A collection of analytical formulas for the impedances of small obstacles is presented.

  3. Fundamental cavity impedance and longitudinal coupled-bunch instabilities at the High Luminosity Large Hadron Collider

    Science.gov (United States)

    Baudrenghien, P.; Mastoridis, T.

    2017-01-01

    The interaction between beam dynamics and the radio frequency (rf) station in circular colliders is complex and can lead to longitudinal coupled-bunch instabilities at high beam currents. The excitation of the cavity higher order modes is traditionally damped using passive devices. But the wakefield developed at the cavity fundamental frequency falls in the frequency range of the rf power system and can, in theory, be compensated by modulating the generator drive. Such a regulation is the responsibility of the low-level rf (llrf) system that measures the cavity field (or beam current) and generates the rf power drive. The Large Hadron Collider (LHC) rf was designed for the nominal LHC parameter of 0.55 A DC beam current. At 7 TeV the synchrotron radiation damping time is 13 hours. Damping of the instability growth rates due to the cavity fundamental (400.789 MHz) can only come from the synchrotron tune spread (Landau damping) and will be very small (time constant in the order of 0.1 s). In this work, the ability of the present llrf compensation to prevent coupled-bunch instabilities with the planned high luminosity LHC (HiLumi LHC) doubling of the beam current to 1.1 A DC is investigated. The paper conclusions are based on the measured performances of the present llrf system. Models of the rf and llrf systems were developed at the LHC start-up. Following comparisons with measurements, the system was parametrized using these models. The parametric model then provides a more realistic estimation of the instability growth rates than an ideal model of the rf blocks. With this modeling approach, the key rf settings can be varied around their set value allowing for a sensitivity analysis (growth rate sensitivity to rf and llrf parameters). Finally, preliminary measurements from the LHC at 0.44 A DC are presented to support the conclusions of this work.

  4. A new monitoring method for electrochemical aggregates by impedance spectroscopy

    Science.gov (United States)

    Kurzweil, P.; Fischle, H.-J.

    A variant of ac impedance spectroscopy is applied to monitor and control electrochemical cells and appliances without need for reference values and knowledge of control points in advance. Electrolyzers, fuels cells, energy stores, sensors and electrochemical reactors are steered to an optimum operating state by continuous evaluation of capacitance and the derivatives thereof. Dry and humid electrode-electrolyte interfaces are distinguished with the aid of the low-frequency impedance. The problem is solved in order to determine electrolyte concentrations unambiguously from electrolyte resistance, although the conductivity of the solution has a maximum and changes nonlinearly with the concentration.

  5. Tapping mode microwave impedance microscopy

    KAUST Repository

    Lai, K.

    2009-01-01

    We report tapping mode microwave impedance imaging based on atomic force microscope platforms. The shielded cantilever probe is critical to localize the tip-sample interaction near the tip apex. The modulated tip-sample impedance can be accurately simulated by the finite-element analysis and the result agrees quantitatively to the experimental data on a series of thin-film dielectric samples. The tapping mode microwave imaging is also superior to the contact mode in that the thermal drift in a long time scale is totally eliminated and an absolute measurement on the dielectric properties is possible. We demonstrated tapping images on working nanodevices, and the data are consistent with the transport results. © 2009 American Institute of Physics.

  6. Impedance analysis of acupuncture points and pathways

    Science.gov (United States)

    Teplan, Michal; Kukučka, Marek; Ondrejkovičová, Alena

    2011-12-01

    Investigation of impedance characteristics of acupuncture points from acoustic to radio frequency range is addressed. Discernment and localization of acupuncture points in initial single subject study was unsuccessfully attempted by impedance map technique. Vector impedance analyses determined possible resonant zones in MHz region.

  7. An Electronic Measurement Instrumentation of the Impedance of a Loaded Fuel Cell or Battery

    OpenAIRE

    2007-01-01

    In this paper we present an inexpensive electronic measurement instrumentation developed in our laboratory, to measure and plot the impedance of a loaded fuel cell or battery. Impedance measurements were taken by using the load modulation method. This instrumentation has been developed around a VXI system stand which controls electronic cards. Software under Hpvee® was developed for automatic measurements and the layout of the impedance of the fuel cell on load. The measurement environment, l...

  8. Impedance-matched Marx generators

    Directory of Open Access Journals (Sweden)

    W. A. Stygar

    2017-04-01

    Full Text Available We have conceived a new class of prime-power sources for pulsed-power accelerators: impedance-matched Marx generators (IMGs. The fundamental building block of an IMG is a brick, which consists of two capacitors connected electrically in series with a single switch. An IMG comprises a single stage or several stages distributed axially and connected in series. Each stage is powered by a single brick or several bricks distributed azimuthally within the stage and connected in parallel. The stages of a multistage IMG drive an impedance-matched coaxial transmission line with a conical center conductor. When the stages are triggered sequentially to launch a coherent traveling wave along the coaxial line, the IMG achieves electromagnetic-power amplification by triggered emission of radiation. Hence a multistage IMG is a pulsed-power analogue of a laser. To illustrate the IMG approach to prime power, we have developed conceptual designs of two ten-stage IMGs with LC time constants on the order of 100 ns. One design includes 20 bricks per stage, and delivers a peak electrical power of 1.05 TW to a matched-impedance 1.22-Ω load. The design generates 113 kV per stage and has a maximum energy efficiency of 89%. The other design includes a single brick per stage, delivers 68 GW to a matched-impedance 19-Ω load, generates 113 kV per stage, and has a maximum energy efficiency of 90%. For a given electrical-power-output time history, an IMG is less expensive and slightly more efficient than a linear transformer driver, since an IMG does not use ferromagnetic cores.

  9. Electrical impedance along connective tissue planes associated with acupuncture meridians

    Directory of Open Access Journals (Sweden)

    Hammerschlag Richard

    2005-05-01

    Full Text Available Abstract Background Acupuncture points and meridians are commonly believed to possess unique electrical properties. The experimental support for this claim is limited given the technical and methodological shortcomings of prior studies. Recent studies indicate a correspondence between acupuncture meridians and connective tissue planes. We hypothesized that segments of acupuncture meridians that are associated with loose connective tissue planes (between muscles or between muscle and bone visible by ultrasound have greater electrical conductance (less electrical impedance than non-meridian, parallel control segments. Methods We used a four-electrode method to measure the electrical impedance along segments of the Pericardium and Spleen meridians and corresponding parallel control segments in 23 human subjects. Meridian segments were determined by palpation and proportional measurements. Connective tissue planes underlying those segments were imaged with an ultrasound scanner. Along each meridian segment, four gold-plated needles were inserted along a straight line and used as electrodes. A parallel series of four control needles were placed 0.8 cm medial to the meridian needles. For each set of four needles, a 3.3 kHz alternating (AC constant amplitude current was introduced at three different amplitudes (20, 40, and 80 μAmps to the outer two needles, while the voltage was measured between the inner two needles. Tissue impedance between the two inner needles was calculated based on Ohm's law (ratio of voltage to current intensity. Results At the Pericardium location, mean tissue impedance was significantly lower at meridian segments (70.4 ± 5.7 Ω compared with control segments (75.0 ± 5.9 Ω (p = 0.0003. At the Spleen location, mean impedance for meridian (67.8 ± 6.8 Ω and control segments (68.5 ± 7.5 Ω were not significantly different (p = 0.70. Conclusion Tissue impedance was on average lower along the Pericardium meridian, but not

  10. Impedance-Source Networks for Electric Power Conversion Part II

    DEFF Research Database (Denmark)

    Siwakoti, Yam P.; Peng, Fang Zheng; Blaabjerg, Frede

    2015-01-01

    Impedance-source networks cover the entire spectrum of electric power conversion applications (dc-dc, dc-ac, ac-dc, ac-ac) controlled and modulated by different modulation strategies to generate the desired dc or ac voltage and current at the output. A comprehensive review of various impedance-source......-network-based power converters has been covered in a previous paper and main topologies were discussed from an application point of view. Now Part II provides a comprehensive review of the most popular control and modulation strategies for impedance-source network-based power converters/inverters. These methods...... topology at a certain power level, switching frequency and demanded dynamic response....

  11. A compact broadband nonsynchronous noncommensurate impedance transformer

    DEFF Research Database (Denmark)

    Zhurbenko, Vitaliy; Kim, Kseniya; Narenda, Kumar

    2012-01-01

    Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison to the tradit......Nonsynchronous noncommensurate impedance transformers consist of a combination of high‐ and low‐impedance transmission lines. High‐impedance lines have narrow tracks in strip and microstrip technology, which allows for high flexibility and miniaturization of the layout in comparison...... to the traditional tapered line transformers. This flexibility of the broadband nonsynchronous noncommensurate impedance transformers is experimentally demonstrated in this article allowing the length reduction by almost three times. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:1832–1835, 2012; View...

  12. A Unified Impedance Model of Voltage-Source Converters with Phase-Locked Loop Effect

    DEFF Research Database (Denmark)

    Wang, Xiongfei; Harnefors, Lennart; Blaabjerg, Frede

    2016-01-01

    This paper proposes a unified impedance model for analyzing the effect of Phase-Locked Loop (PLL) on the stability of grid-connected voltage-source converters. In the approach, the dq-frame impedance model is transformed into the stationary αβ-frame by means of complex transfer functions and comp......This paper proposes a unified impedance model for analyzing the effect of Phase-Locked Loop (PLL) on the stability of grid-connected voltage-source converters. In the approach, the dq-frame impedance model is transformed into the stationary αβ-frame by means of complex transfer functions...... characterized for the current control in the rotating dq-frame and the stationary αβ-frame. Case studies based on the unified impedance model are presented, which are then verified in the time-domain simulations and experiments. The results closely correlate with the impedance-based analysis....

  13. An Impedance-Based Stability Analysis Method for Paralleled Voltage Source Converters

    DEFF Research Database (Denmark)

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

    2014-01-01

    This paper analyses the stability of paralleled voltage source converters in AC distributed power systems. An impedance-based stability analysis method is presented based on the Nyquist criterion for multiloop system. Instead of deriving the impedance ratio as usual, the system stability...... is assessed based on a series of Nyquist diagrams drawn for the terminal impedance of each converter. Thus, the effect of the right half-plane zeros of terminal impedances in the derivation of impedance ratio for paralleled source-source converters is avoided. The interaction between the terminal impedance...... of converter and the passive network can also be predicted by the Nyquist diagrams. This method is applied to evaluate the current and voltage controller interactions of converters in both grid-connected and islanded operations. Simulations and experimental results verify the effectiveness of theoretical...

  14. Bioelectric impedance phase angle in breast carcinoma

    Directory of Open Access Journals (Sweden)

    Ruchi Tyagi

    2014-01-01

    Full Text Available Context: Worldwide breast cancer is the most frequently diagnosed life threatening cancer and the leading cause of death in women. Bioelectric impedance analysis (BIA affords an emerging opportunity to assess prognosis because of its ability to non invasively assess cell and plasma membrane structure and function by means of phase angle. Aims: To compare the phase angle between patients of breast cancer and their matched control with the help of BIA. Settings and Design: After taking clearance from ethical committee, a total of 34 female cases of histologically proven infiltrating ductal breast carcinoma were included from the surgery IPD, department of surgery. Equal numbers of the matched controls were recruited from the friends and relatives of cases. Materials and Methods: Bio Electrical Impedance Analyzer (BIA BODY STAT QUAD SCAN 4000 was used to measure resistance (R and reactance (Xc by recording a voltage drop in applied current. Phase angle is the ratio of reactance to resistance and is a measure of cell vitality. Statistical analysis used: Unpaired "t" test was applied. Results: In control group, the phase angle showed a mean of 5.479 whereas in test group, it showed a mean value of 4.726. The P value showed a significant difference (P < 0.0001. The smaller the phase angle values were higher was the tumor, nodes, metastases (TNM staging. The phase angles differed significantly from the healthy age matched control values. Conclusions: This study demonstrated that phase angle is a strong predictor of severity of breast cancer and differed significantly between the two groups.

  15. Application of plant impedance for diagnosing plant disease

    Science.gov (United States)

    Xu, Huirong; Jiang, Xuesong; Zhu, Shengpan; Ying, Yibin

    2006-10-01

    Biological cells have components acting as electrical elements that maintain the health of the cell by regulation of the electrical charge content. Plant impedance is decided by the state of plant physiology and pathology. Plant physiology and pathology can be studies by measuring plant impedance. The effect of Cucumber Mosaic Virus red bean isolate (CMV-RB) on electrical resistance of tomato leaves was studied by the method of impedance measurement. It was found that the value of resistance of tomato leaves infected with CMV-RB was smaller than that in sound plant leaves. This decrease of impedances in leaf tissue was occurred with increased severity of disease. The decrease of resistance of tomato leaves infected with CMV-RB could be detected by electrical resistance detecting within 4 days after inoculation even though significant visible differences between the control and the infected plants were not noted, so that the technique for measurement of tomato leaf tissue impedance is a rapid, clever, simple method on diagnosis of plant disease.

  16. Impedance and instabilities in the NLC damping rings

    Energy Technology Data Exchange (ETDEWEB)

    Corlett,J.; Li, D.; Pivi, M.; Rimmer, R.; DeSantis, S.; Wolski, A.; Novokhatski,A.; Ng, C.

    2001-06-12

    We report on impedance calculations and single-bunch and multi-bunch instabilities in the NLC damping rings. Preliminary designs of vacuum chambers and major components have addressed beam impedance issues, with the desire to increase instability current thresholds and reducing growth rates. MAFIA calculations of short-range and long-range wakefields have allowed computations of growth rates and thresholds, which are presented here. Resistive wall instability dominates long-range effects, and requires a broadband feedback system to control coupled-bunch motion. Growth rates are within the range addressable by current feedback system technologies. Single-bunch instability thresholds are safely above nominal operating current.

  17. Impedance characterization of PV modules in outdoor conditions

    DEFF Research Database (Denmark)

    Oprea, Matei-lon; Thorsteinsson, Sune; Spataru, Sergiu

    2016-01-01

    Impedance spectroscopy (IS) has been used for laboratory characterizations of photovoltaic (PV) technologies under well controlled conditions. This work applies IS for outdoor characterization of PV panels, in order to observe the effect of irradiance (G) and temperature (T) on the PV module...

  18. Lower leg electrical impedance after distal bypass surgery

    DEFF Research Database (Denmark)

    Belanger, G K; Bolbjerg, M L; Heegaard, N H;

    1998-01-01

    Electrical impedance was determined in 13 patients following distal bypass surgery to evaluate lower leg oedema as reflected by its circumference. Tissue injury was assessed by the plasma concentration of muscle enzymes. After surgery, the volume of the control lower leg increased from 1250 (816...... to be a useful method for the evaluation of lower leg oedema after distal bypass surgery....

  19. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2004-06-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  20. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-10-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  1. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-04-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  2. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2005-01-17

    This project aimed at developing a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GTI. GTI proposed to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or non-metallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment

  3. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2003-01-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  4. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba; Christopher J. Ziolkowski

    2004-10-29

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or non-metallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  5. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2002-08-30

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  6. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2004-02-01

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  7. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2002-11-27

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a thin film sensor conformal with the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is capacitively coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD

  8. DIFFERENTIAL SOIL IMPEDANCE OBSTACLE DETECTION

    Energy Technology Data Exchange (ETDEWEB)

    Maximillian J. Kieba

    2004-05-03

    This project develops a new and unique obstacle detection sensor for horizontal directional drilling (HDD) equipment. The development of this new technology will greatly improve the reliability and safety of natural gas HDD construction practices. This sensor utilizes a differential soil impedance measurement technique that will be sensitive to the presence of plastic and ceramic, as well as metallic obstacles. The use of HDD equipment has risen significantly in the gas industry because HDD provides a much more cost-effective and less disruptive method for gas pipe installation than older, trenching methods. However, there have been isolated strikes of underground utilities by HDD equipment, which may have been avoided if methods were available to detect other underground obstacles when using HDD systems. GTI advisors from the gas industry have ranked the value of solving the obstacle detection problem as the most important research and development project for GTI to pursue using Federal Energy Regulatory Commission (FERC) funds available through its industry partner, GRI. GTI proposes to develop a prototype down-hole sensor system that is simple and compact. The sensor utilizes an impedance measurement technique that is sensitive to the presence of metallic or nonmetallic objects in the proximity of the HDD head. The system will use a simple sensor incorporated into the drill head. The impedance of the soil will be measured with a low frequency signal injected through the drill head itself. A pair of bridge type impedance sensors, mounted orthogonal to one another, is coupled to the soil. Inclusions in the soil will cause changes to the sensor balance distinguishable from homogeneous soil. The sensor will provide range and direction data for obstacles near the HDD head. The goal is to provide a simple, robust system that provides the information required to avoid obstacles. This must be done within the size and ruggedness constraints of the HDD equipment. Imaging

  9. Impedance spectroscopy of food mycotoxins

    Science.gov (United States)

    Bilyy, Oleksandr I.; Yaremyk, Roman Ya.; Kotsyumbas, Ihor Ya.; Kotsyumbas, Halyna I.

    2012-01-01

    A new analytical method of high-selective detection of mycotoxins in food and feed are considered. A method is based on optical registration the changes of conduct of the electric polarized bacterial agents in solution at the action of the external gradient electric fields. Measuring are conducted in integrated electrode-optical cuvette of the special construction, which provides the photometric analysis of forward motion of the objects registration in liquid solution under act of the enclosed electric field and simultaneous registration of kinetics of change of electrical impedance parameters solution and electrode system.

  10. Observations involving broadband impedance modelling

    Energy Technology Data Exchange (ETDEWEB)

    Berg, J.S.

    1995-08-01

    Results for single- and multi-bunch instabilities can be significantly affected by the precise model that is used for the broadband impendance. This paper discusses three aspects of broadband impendance modeling. The first is an observation of the effect that a seemingly minor change in an impedance model has on the single-bunch mode coupling threshold. The second is a successful attempt to construct a model for the high-frequency tails of an r.f cavity. The last is a discussion of requirements for the mathematical form of an impendance which follow from the general properties of impendances.

  11. A Harmonic Impedance Measurement System for Reduction of Harmonics in the Electricity Grid

    NARCIS (Netherlands)

    Heskes, P.J.M.; Myrzik, J.M.A.; Kling, W.L.

    2009-01-01

    This paper describes the development of a Complex Harmonic Impedance Measurement system, called the CHIME-system. This system performs on-line impedance measurements in the electricity grid and will be designed for implementation in Digital Signal Processor (DSP) control systems of grid-connected el

  12. Online grid impedance estimation for single-phase grid-connected systems using PQ variations

    DEFF Research Database (Denmark)

    Ciobotaru, Mihai; Teodorescu, Remus; Rodriguez, Pedro;

    2007-01-01

    algorithms are used in order to estimate the value of the grid impedance. The online grid impedance estimation method can be used for compliance with the anti-islanding standard requirements (IEEE1574, IEEE929 and VDE0126) and for adaptive control of the grid-connected converters. The proposed method...

  13. Journal bearing impedance descriptions for rotordynamic applications

    Science.gov (United States)

    Childs, D.; Moes, H.; Van Leeuwen, H.

    1976-01-01

    The paper deals with the development of analytic descriptions for plain circumferentially-symmetric fluid journal bearings, which are suitable for use in rotor dynamic analysis. The bearing impedance vector is introduced, which defines the bearing reaction force components as a function of the bearing motion. Impedances are derived directly for the Ocvirk (short) and Sommerfeld (long) bearings, and the relationships between the impedance vector and the more familiar mobility vector are developed and used to derive analytic impedance for finite-length bearings. The static correctness of the finite-length cavitating impedance is verified. Analytic stiffness and damping coefficient definitions are derived in terms of an impedance vector for small motion around an equilibrium position and demonstrated for the finite-length cavitating impedance. Nonlinear transient rotordynamic simulations are presented for the short pi and 2-pi impedances and the finite-length cavitating impedance. It is shown that finite-length impedance yields more accurate results for substantially less computer time than the short-bearing numerical-pressure-integration approach.

  14. Spheromak Impedance and Current Amplification

    Energy Technology Data Exchange (ETDEWEB)

    Fowler, T K; Hua, D D; Stallard, B W

    2002-01-31

    It is shown that high current amplification can be achieved only by injecting helicity on the timescale for reconnection, {tau}{sub REC}, which determines the effective impedance of the spheromak. An approximate equation for current amplification is: dI{sub TOR}{sup 2}/dt {approx} I{sup 2}/{tau}{sub REC} - I{sub TOR}{sup 2}/{tau}{sub closed} where I is the gun current, I{sub TOR} is the spheromak toroidal current and {tau}{sub CLOSED} is the ohmic decay time of the spheromak. Achieving high current amplification, I{sub TOR} >> I, requires {tau}{sub REC} <<{tau}{sub CLOSED}. For resistive reconnection, this requires reconnection in a cold zone feeding helicity into a hot zone. Here we propose an impedance model based on these ideas in a form that can be implemented in the Corsica-based helicity transport code. The most important feature of the model is the possibility that {tau}{sub REC} actually increases as the spheromak temperature increases, perhaps accounting for the ''voltage sag'' observed in some experiments, and a tendency toward a constant ratio of field to current, B {proportional_to} I, or I{sub TOR} {approx} I. Program implications are discussed.

  15. Algorithmic Error Correction of Impedance Measuring Sensors

    Science.gov (United States)

    Starostenko, Oleg; Alarcon-Aquino, Vicente; Hernandez, Wilmar; Sergiyenko, Oleg; Tyrsa, Vira

    2009-01-01

    This paper describes novel design concepts and some advanced techniques proposed for increasing the accuracy of low cost impedance measuring devices without reduction of operational speed. The proposed structural method for algorithmic error correction and iterating correction method provide linearization of transfer functions of the measuring sensor and signal conditioning converter, which contribute the principal additive and relative measurement errors. Some measuring systems have been implemented in order to estimate in practice the performance of the proposed methods. Particularly, a measuring system for analysis of C-V, G-V characteristics has been designed and constructed. It has been tested during technological process control of charge-coupled device CCD manufacturing. The obtained results are discussed in order to define a reasonable range of applied methods, their utility, and performance. PMID:22303177

  16. Algorithmic Error Correction of Impedance Measuring Sensors

    Directory of Open Access Journals (Sweden)

    Vira Tyrsa

    2009-12-01

    Full Text Available This paper describes novel design concepts and some advanced techniques proposed for increasing the accuracy of low cost impedance measuring devices without reduction of operational speed. The proposed structural method for algorithmic error correction and iterating correction method provide linearization of transfer functions of the measuring sensor and signal conditioning converter, which contribute the principal additive and relative measurement errors. Some measuring systems have been implemented in order to estimate in practice the performance of the proposed methods. Particularly, a measuring system for analysis of C-V, G-V characteristics has been designed and constructed. It has been tested during technological process control of charge-coupled device CCD manufacturing. The obtained results are discussed in order to define a reasonable range of applied methods, their utility, and performance.

  17. Pumping slots: impedances and power losses

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S. [Maryland Univ., College Park, MD (United States). Dept. of Physics

    1996-08-01

    Contributions of pumping slots to the beam coupling impedances and power losses in a B-factory ring are considered. While their leading contribution is to the inductive impedance, for high-intensity machines with short bunches like e{sup +}e{sup -} B-factories the real part of the impedance and related loss factors are also important. Using an analytical approach we calculate the coupling impedances and loss factors due to slots in a ring with an arbitrary cross section of the vacuum chamber. Effects of the slot tilt on the beam impedance are also considered, and restrictions on the tilt angle are derived from limitations on the impedance increase. The power leakage through the slots is discussed briefly. The results are applied to the KEK B-factory. (author)

  18. The low level radio frequency control system for DC-SRF photo-injector at Peking University

    CERN Document Server

    Wang, Fang; Lin, Lin; Hao, Jiankui; Quan, Shengwen; Zhang, Baocheng; Liu, Kexin

    2014-01-01

    A low level radio frequency (LLRF) control system is designed and constructed at Peking University, which is for the DC-SRF photo injector operating at 2K. Besides with continuous wave (CW), the system is also reliable with pulsed RF and pulsed beam, the stability of amplitude and phase can achieve 0.13% and 0.1{\\deg}respectively. It is worth noting that the system works perfectly when the cavity is driven at both generator driven resonator (GDR) and self-excited loop (SEL), the latter is useful in measuring the performance of the cavity.

  19. M10.6.9: Design and fabrication of AMC modules for controlling step motors, piezo and waveguide tuners

    CERN Document Server

    Przygoda, K; Kielar, E

    2011-01-01

    FLASH accelerator is using superconducting RF cavities to accelerate electron beam. These cavities must be precisely tuned to RF frequency due to very high Q factor (~109 unloaded Q and ~106 loaded Q). They are tuned by slight dimension change (particularly length) induced by tuners driven by step motors. For high gradients (~20MV/m and more) the cavities are dynamically detuned during RF pulse due to Lorentz Force Detuning (LFD). To keep them in resonance the fast tuners with piezos are used. Both slow and fast tuners need the control integrated with the LLRF system.

  20. Signal Processing for the Impedance Measurement on an Electrochemical Generator

    Directory of Open Access Journals (Sweden)

    El-Hassane AGLZIM

    2008-04-01

    Full Text Available Improving the life time of batteries or fuel cells requires the optimization of components such as membranes and electrodes and enhancement of the flow of gases [1], [2]. These goals could be reached by using a real time measurement on loaded generator. The impedance spectroscopy is a new way that was recently investigated. In this paper, we present an electronic measurement instrumentation developed in our laboratory to measure and plot the impedance of a loaded electrochemical generator like batteries and fuel cells. Impedance measures were done according to variations of the frequency in a larger band than what is usually used. The electronic instrumentation is controlled by Hpvee® software which allows us to plot the Nyquist graph of the electrochemical generator impedance. The theoretical results obtained in simulation under Pspice® confirm the choice of the method and its advantage. For safety reasons, the experimental preliminary tests were done on a 12 V vehicle battery, having an input current of 330 A and a capacity of 40 Ah and are now extended to a fuel cell. The results were plotted at various nominal voltages of the battery (12.7 V, 10 V, 8 V and 5 V and with two imposed currents (0.6 A and 4 A. The Nyquist diagram resulting from the experimental data enable us to show an influence of the load of the battery on its internal impedance. The similitude in the graph form and in order of magnitude of the values obtained (both theoretical and practical enables us to validate our electronic measurement instrumentation. Different sensors (temperature, pressure were placed around the device under test (DUT. These influence parameters were permanently recorded. Results presented here concern a classic loaded 12 V vehicle battery. The Nyquist diagram resulting from the experimental data confirms the influence of the load of the DUT on its internal impedance.

  1. Electrical impedance imaging of water distribution in the root zone

    Science.gov (United States)

    Newill, P.; Karadaglić, D.; Podd, F.; Grieve, B. D.; York, T. A.

    2014-05-01

    The paper describes a technique that is proposed for imaging water transport in and around the root zone of plants using distributed measurements of electrical impedance. The technique has the potential to analyse sub-surface phenotypes, for instance drought tolerance traits in crop breeding programmes. The technical aim is to implement an automated, low cost, instrument for high-throughput screening. Ultimately the technique is targeted at in-field, on-line, measurements. For demonstration purposes the present work considers measurements on laboratory scale rhizotrons housing growing maize plants. Each rhizotron is fitted with 60 electrodes in a rectangular array. To reduce electrochemical effects the capacitively coupled contactless conductivity (C4D) electrodes have an insulating layer on the surface and the resistance of the bulk material is deduced from spectroscopic considerations. Electrical impedance is measured between pairs of electrodes to build up a two-dimensional map. A modified electrical model of such electrodes is proposed which includes the resistive and reactive components of both the insulating layer and the bulk material. Measurements taken on a parallel-plate test cell containing water confirm that the C4D technique is able to measure electrical impedance. The test cell has been used to explore the effects of water content, compaction and temperature on measurements in soil. Results confirm that electrical impedance measurements are very sensitive to moisture content. Impedance fraction changes up to 20% are observed due to compaction up to a pressure of 0.21 kg cm-2 and a temperature fraction sensitivity of about 2%/°C. The effects of compaction and temperature are most significant under dry conditions. Measurements on growing maize reveal the changes in impedance across the rhizotron over a period of several weeks. Results are compared to a control vessel housing only soil.

  2. Impedance Spectroscopy of Human Blood

    Science.gov (United States)

    Mesa, Francisco; Bernal, José J.; Sosa, Modesto A.; Villagómez, Julio C.; Palomares, Pascual

    2004-09-01

    The blood is one of the corporal fluids more used with analytical purposes. When the blood is extracted, immediately it is affected by agents that act on it, producing transformations in its elements. Among the effects of these transformations the hemolysis phenomenon stands out, which consists of the membrane rupture and possible death of the red blood cells. The main purpose of this investigation was the quantification of this phenomenon. A Solartron SI-1260 Impedance Spectrometer was used, which covers a frequency range of work from 1 μHz to 10 MHz, and its accuracy has been tested in the accomplishment of several applications. Measurements were performed on 3 mL human blood samples, from healthy donors. Reactive strips for sugar test of 2 μL, from Bayer, were used as electrodes, which allow gathering a portion of the sample, to be analyzed by the spectrometer. Preliminary results of these measurements are presented.

  3. Lorentz Force Electrical Impedance Tomography

    CERN Document Server

    Grasland-Mongrain, Pol; Chapelon, Jean-Yves; Lafon, Cyril

    2014-01-01

    This article describes a method called Lorentz Force Electrical Impedance Tomography. The electrical conductivity of biological tissues can be measured through their sonication in a magnetic field: the vibration of the tissues inside the field induces an electrical current by Lorentz force. This current, detected by electrodes placed around the sample, is proportional to the ultrasonic pressure, to the strength of the magnetic field and to the electrical conductivity gradient along the acoustic axis. By focusing at different places inside the sample, a map of the electrical conductivity gradient can be established. In this study experiments were conducted on a gelatin phantom and on a beef sample, successively placed in a 300 mT magnetic field and sonicated with an ultrasonic transducer focused at 21 cm emitting 500 kHz bursts. Although all interfaces are not visible, in this exploratory study a good correlation is observed between the electrical conductivity image and the ultrasonic image. This method offers...

  4. Intelligent Platform Management Controller for Low Level RF Control System ATCA Carrier Board

    CERN Document Server

    Predki, Pawel

    2011-01-01

    High availability and reliability are among the most desirable features of control systems in modern High-Energy Physics (HEP) and other big-scale scientific experiments. One of the recent developments that has influenced this field was the emergence of the Advanced Telecommunications Computing Architecture (ATCA). Designed for the telecommunications industry it has been successfully applied in other domains such as accelerator control systems. A good example is the application of ATCA stan- dard for the design of Low Level RF (LLRF) control system for the X-Ray Free Electron Laser (XFEL) being developed in Deutsches Elektronen Synchrotron (DESY). Reliability and availability requirements for such a device play a crucial role among other parameters. Thus, the ATCA standard, with five- nines availability, is considered one of the best candidates for this system. This article focuses on the central management unit of every ATCA board, namely the Intelligent Platform Management Controller (IPMC), developed for t...

  5. New OTRA-Based Generalized Impedance Simulator

    OpenAIRE

    Ashish Gupta; Raj Senani; Bhaskar, D. R.; Singh, A. K.

    2013-01-01

    Operational transresistance amplifier (OTRA) has attracted considerable attention in the recent literature in several applications such as impedance simulation, universal biquad filter realization, realization of sinusoidal oscillators and multivibrators. However, to the best knowledge of the authors, any OTRA-based generalized impedance simulator circuits have not been reported so far. The purpose of this paper is to present such a circuit.

  6. Quadratic Boost A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Chub, Andrii

    2016-01-01

    A novel quadratic boost A-source impedance network is proposed to realize converters that demand very high voltage gain. To satisfy the requirement, the network uses an autotransformer where the obtained gain is quadratically dependent on the duty ratio and is unmatched by any existing impedance ...

  7. Quantification of coating aging using impedance measurements

    NARCIS (Netherlands)

    Westing, E.P.M. van; Weijde, D.H. van der; Vreijling, M.P.W.; Ferrari, G.M.; Wit, J.H.W. de

    1998-01-01

    This chapter shows the application results of a novel approach to quantify the ageing of organic coatings using impedance measurements. The ageing quantification is based on the typical impedance behaviour of barrier coatings in immersion. This immersion behaviour is used to determine the limiting c

  8. Impedance of a slotted-pipe kicker

    Energy Technology Data Exchange (ETDEWEB)

    Feng Zhou [Academia Sinica, Beijing, BJ (China). Inst. of High Energy Physics

    1996-08-01

    This paper introduces the principle of a new slotted kicker simply, which is made by using vacuum pipe itself with proper slits as current conductors, and then, presents a rough estimation of its longitudinal and transverse impedance, respectively. Calculation shows that its impedance is reduced significantly compared to our present air-coil kicker. (author)

  9. Possibilities of electrical impedance tomography in gynecology

    Science.gov (United States)

    V, Trokhanova O.; A, Chijova Y.; B, Okhapkin M.; V, Korjenevsky A.; S, Tuykin T.

    2013-04-01

    The paper describes results of comprehensive EIT diagnostics of mammary glands and cervix. The data were obtained from examinations of 170 patients by EIT system MEM (multi-frequency electrical impedance mammograph) and EIT system GIT (gynecological impedance tomograph). Mutual dependence is discussed.

  10. Causal impedance matching for broadband hybrid noise absorption.

    Science.gov (United States)

    Yuan, Jing

    2003-06-01

    The complementary strengths and weaknesses of passive and active noise control (ANC) methods have motivated many researchers to develop hybrid noise absorbers that integrate both control strategies. The impedance matching technique (IMT) is the most effective for such a purpose. An unsolved problem with available IMT schemes is the a priori reference signal that limits IMT applications. This study proposes the use of the forward wave, available by the two-microphone method, as the reference signal. Due to inevitable errors in wave separation and inlet reflection of the control signal, the absorber becomes a feedback system. A simple and stable ANC is developed for impedance matching without the a priori reference signal. The proposed absorber has an absorption coefficient of 0.9 or above in a frequency range of 60-850 Hz. It is stable in the presence of sensor mismatch and robust with respect to significant variation of inlet boundary conditions.

  11. Installation and Commissioning of the Resonant Frequency Control Cooling System

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Hyeokjung; Seol, Kyungtae; Kim, Hansung; Jang, Jiho; Cho, Yongsub [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2013-05-15

    Total 11 sets of Resonant Frequency Control Cooling System (RCCS) are used to control the resonance frequency of the 100-MeV DTL. The specifications of the RCCS are summarized. The RCCS should cover the temperature from 21 .deg. C to 33 .deg. C, heat load from magnet power only to full RF power in addition to the magnet power. The stability of the temperature control is less than 0.1 .deg. C. The control input variable comes from the resonance frequency error from the low level RF (LLRF) system. All RCCSs were installed and tested. In this paper, the installation and initial test results of the RCCS are presented. The standalone test of the RCCS for 100-MeV DTL was carried out. The results showed that the chiller temperature fluctuated above the specification mainly because the chiller controller was not properly tuned, but the RCCS with two independent control valves could be operated to give the required stability.

  12. Online impedance matching system for ICRH-RF experiments on SST-1 tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, R.; Singh, M.; Jadav, H.M.; Mishra, K.; Singh, Raj; Kulkarni, S.V.; Bora, D.

    2015-11-15

    High-power radio frequency (RF) heating system in the frequency range of ion cyclotron range of frequencies (ICRF) on tokamak needs a mechanism for matching impedance seen by the antenna in presence of plasma to the generator output impedance for maximum transfer of RF power to the plasma with minimum reflections to avoid damage to the generator. The impedance of the antenna is strongly dependent on edge plasma parameters and the impedance sometimes changes as fast as 10{sup −4} s, while the RF generators used can deliver full power only into constant load impedance. Hence, the matching system with dynamic response in between generator and antenna is very much essential for high power ICRF experiments when the plasma is of longer duration with variable load impedance. For ICRF system on SST-1 tokamak, two automatic matching systems are employed each for one transmission line, which consists of motorized stub tuners and phase shifters to match the antenna impedance in the time scale of 120 ms. As a part of initial testing, online impedance matching system is tested with individual transmission lines and then both the lines are matched simultaneously on a variable dummy load which simulates the plasma load. In order to deliver power to both the lines from a single RF generator, hybrid coupler is used which also protects RF generator from reflections up to certain extent. However for hybrid coupler has to work properly and both the lines should see same load impedance. The automatic matching system is installed on tokamak state super-conducting tokamak (SST-1) and is tested up to 140 kW power in the vacuum vessel of the tokamak. Here we present the details of the online matching system and its testing results. The significant result is that we could match the variable load impedance with the generator impedance within 120 ms by suitably adjusting the step counts of the motor controller.

  13. Impedance Spectroscopy of Dielectrics and Electronic Conductors

    DEFF Research Database (Denmark)

    Bonanos, Nikolaos; Pissis, Polycarpos; Macdonald, J. Ross

    2013-01-01

    Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property, such as admi......Impedance spectroscopy is used for the characterization of materials, such as electroceramics, solid and liquid electrochemical cells, dielectrics and also fully integrated devices, such as fuel cells. It consists of measuring the electrical impedance - or a closely related property......, and procedures for the correction of measurement errors. The applications of impedance spectroscopy are illustrated with examples from electroceramics and polymer-based dielectric systems. The way in which the technique is applied to the two classes of materials is compared with reference to the different models...

  14. Fractional Order Element Based Impedance Matching

    KAUST Repository

    Radwan, Ahmed Gomaa

    2014-06-24

    Disclosed are various embodiments of methods and systems related to fractional order element based impedance matching. In one embodiment, a method includes aligning a traditional Smith chart (|.alpha.|=1) with a fractional order Smith chart (|.alpha.|.noteq.1). A load impedance is located on the traditional Smith chart and projected onto the fractional order Smith chart. A fractional order matching element is determined by transitioning along a matching circle of the fractional order Smith chart based at least in part upon characteristic line impedance. In another embodiment, a system includes a fractional order impedance matching application executed in a computing device. The fractional order impedance matching application includes logic that obtains a first set of Smith chart coordinates at a first order, determines a second set of Smith chart coordinates at a second order, and determines a fractional order matching element from the second set of Smith chart coordinates.

  15. Update of the SPS Impedance Model

    CERN Document Server

    Salvant, B; Zannini, C; Arduini, G; Berrig, O; Caspers, F; Grudiev, A; Métral, E; Rumolo, G; Shaposhnikova, E; Zotter, B; Migliorati, M; Spataro, B

    2010-01-01

    The beam coupling impedance of the CERN SPS is expected to be one of the limitations to an intensity upgrade of the LHC complex. In order to be able to reduce the SPS impedance, its main contributors need to be identified. An impedance model for the SPS has been gathered from theoretical calculations, electromagnetic simulations and bench measurements of single SPS elements. The current model accounts for the longitudinal and transverse impedance of the kickers, the horizontal and vertical electrostatic beam position monitors, the RF cavities and the 6.7 km beam pipe. In order to assess the validity of this model, macroparticle simulations of a bunch interacting with this updated SPS impedance model are compared to measurements performed with the SPS beam.

  16. HIRFL数字化高频低电平控制系统研究%Research of Digital Low Level Radio Frequency Control System for HIRFL

    Institute of Scientific and Technical Information of China (English)

    丛岩; 许哲; 李刚; 王贤武; 孙列鹏; 仪孝平

    2012-01-01

    In order to ensure that the beam quality is well enough, we need to precisely control the frequen- cy, amplitude and phase of cavity electric field. Traditional control system consists of amplitude loop and phase loop. And these two loops control amplitude and phase stability respectively. The digital low level radio frequency (LLRF) system, which uses advanced digital control technology, needs only one feed-back loop to control amplitude and phase stability. The phase control precision and stability of the system are higher than the traditional control system. The LLRF system is based on field programmable gate array (FPGA) and digital signal processing (DSP), and implemented by direct digital frequency synthesis (DDS) and digital orthogonal modulation and demodulation (I/Q) technology. The digital LLRF system has been tested in a long-term stability and high-power experiments. The amplitude deviation is lower than ± 1 , and phase control accuracy is within ±1.

  17. Fundamental impedance identification method for grid-connected voltage source inverters

    DEFF Research Database (Denmark)

    Sun, Xiaofeng; Chen, J.; Guerrero, Josep M.

    2014-01-01

    Considering the importance of line fundamental impedance from the inverter to the point of common coupling (PCC) in microgrids, this study analyses the influence of fundamental impedance on system stability. Line fundamental impedance values not only apply to decoupled droop control, which can...... realise accurate control between active and reactive power, but also regulate the droop coefficient to eliminate system circulation, realise power sharing and improve system stability when a multi-distributed generation system operates in parallel. Moreover, the PCC can sense grid fault on the basis...

  18. Iterative Learning Impedance for Lower Limb Rehabilitation Robot

    Directory of Open Access Journals (Sweden)

    Chenhui Guo

    2017-01-01

    Full Text Available This paper discusses the problem of squatting training of stroke patients. The main idea is to correct the patient’s training trajectory through an iterative learning control (ILC method. To obtain better rehabilitation effect, a patient will typically be required to practice a reference posture for many times, while most of active training methods can hardly keep the patients training with correct posture. Instead of the conventional ILC strategy, an impedance-based iterative learning method is proposed to regulate the impedance value dynamically and smartly which will help patients correct their posture gradually and perform better. To facilitate impedance-based ILC, we propose two objectives. The first objective is to find the suitable values of impedance based on the ILC scheme. The second objective is to search the moderate learning convergence speed and robustness in the iterative domain. The simulation and experimental results demonstrate that the performance of trajectory tracking will be improved greatly via the proposed algorithm.

  19. Impedance matching at arterial bifurcations.

    Science.gov (United States)

    Brown, N

    1993-01-01

    Reflections of pulse waves will occur in arterial bifurcations unless the impedance is matched continuously through changing geometric and elastic properties. A theoretical model is presented which minimizes pulse wave reflection through bifurcations. The model accounts for the observed linear changes in area within the bifurcation, generalizes the theory to asymmetrical bifurcations, characterizes changes in elastic properties from parent to daughter arteries, and assesses the effect of branch angle on the mechanical properties of daughter vessels. In contradistinction to previous models, reflections cannot be minimized without changes in elastic properties through bifurcations. The theoretical model predicts that in bifurcations with area ratios (beta) less than 1.0 Young's moduli of daughter vessels may be less than that in the parent vessel if the Womersley parameter alpha in the parent vessel is less than 5. Larger area ratios in bifurcations are accompanied by greater increases in Young's moduli of branches. For an idealized symmetric aortic bifurcation (alpha = 10) with branching angles theta = 30 degrees (opening angle 60 degrees) Young's modulus of common iliac arteries relative to that of the distal abdominal aorta has an increase of 1.05, 1.68 and 2.25 for area ratio of 0.8, 1.0 and 1.15, respectively. These predictions are consistent with the observed increases in Young's moduli of peripheral vessels.(ABSTRACT TRUNCATED AT 250 WORDS)

  20. Electrical impedance of acupuncture meridians: the relevance of subcutaneous collagenous bands.

    Directory of Open Access Journals (Sweden)

    Andrew C Ahn

    Full Text Available BACKGROUND: The scientific basis for acupuncture meridians is unknown. Past studies have suggested that acupuncture meridians are physiologically characterized by low electrical impedance and anatomically associated with connective tissue planes. We are interested in seeing whether acupuncture meridians are associated with lower electrical impedance and whether ultrasound-derived measures--specifically echogenic collagenous bands--can account for these impedance differences. METHODS/RESULTS: In 28 healthy subjects, we assessed electrical impedance of skin and underlying subcutaneous connective tissue using a four needle-electrode approach. The impedances were obtained at 10 kHz and 100 kHz frequencies and at three body sites - upper arm (Large Intestine meridian, thigh (Liver, and lower leg (Bladder. Meridian locations were determined by acupuncturists. Ultrasound images were obtained to characterize the anatomical features at each measured site. We found significantly reduced electrical impedance at the Large Intestine meridian compared to adjacent control for both frequencies. No significant decrease in impedance was found at the Liver or Bladder meridian. Greater subcutaneous echogenic densities were significantly associated with reduced impedances in both within-site (meridian vs. adjacent control and between-site (arm vs. thigh vs. lower leg analyses. This relationship remained significant in multivariable analyses which also accounted for gender, needle penetration depth, subcutaneous layer thickness, and other ultrasound-derived measures. CONCLUSION/SIGNIFICANCE: Collagenous bands, represented by increased ultrasound echogenicity, are significantly associated with lower electrical impedance and may account for reduced impedances previously reported at acupuncture meridians. This finding may provide important insights into the nature of acupuncture meridians and the relevance of collagen in bioelectrical measurements.

  1. Impedance Discontinuity Reduction Between High-Speed Differential Connectors and PCB Interfaces

    Science.gov (United States)

    Navidi, Sal; Agdinaoay, Rodell; Walter, Keith

    2013-01-01

    High-speed serial communication (i.e., Gigabit Ethernet) requires differential transmission and controlled impedances. Impedance control is essential throughout cabling, connector, and circuit board construction. An impedance discontinuity arises at the interface of a high-speed quadrax and twinax connectors and the attached printed circuit board (PCB). This discontinuity usually is lower impedance since the relative dielectric constant of the board is higher (i.e., polyimide approx. = 4) than the connector (Teflon approx. = 2.25). The discontinuity can be observed in transmit or receive eye diagrams, and can reduce the effective link margin of serial data networks. High-speed serial data network transmission improvements can be made at the connector-to-board interfaces as well as improving differential via hole impedances. The impedance discontinuity was improved by 10 percent by drilling a 20-mil (approx. = 0.5-mm) hole in between the pin of a differential connector spaced 55 mils (approx. = 1.4 mm) apart as it is attached to the PCB. The effective dielectric constant of the board can be lowered by drilling holes into the board material between the differential lines in a quadrax or twinax connector attachment points. The differential impedance is inversely proportional to the square root of the relative dielectric constant. This increases the differential impedance and thus reduces the above described impedance discontinuity. The differential via hole impedance can also be increased in the same manner. This technique can be extended to multiple smaller drilled holes as well as tapered holes (i.e., big in the middle followed by smaller ones diagonally).

  2. Rotor damage detection by using piezoelectric impedance

    Science.gov (United States)

    Qin, Y.; Tao, Y.; Mao, Y. F.

    2016-04-01

    Rotor is a core component of rotary machinery. Once the rotor has the damage, it may lead to a major accident. Thus the quantitative rotor damage detection method based on piezoelectric impedance is studied in this paper. With the governing equation of piezoelectric transducer (PZT) in a cylindrical coordinate, the displacement along the radius direction is derived. The charge of PZT is calculated by the electric displacement. Then, by the use of the obtained displacement and charge, an analytic piezoelectric impedance model of the rotor is built. Given the circular boundary condition of a rotor, annular elements are used as the analyzed objects and spectral element method is used to set up the damage detection model. The Electro-Mechanical (E/M) coupled impedance expression of an undamaged rotor is deduced with the application of a low-cost impedance test circuit. A Taylor expansion method is used to obtain the approximate E/M coupled impedance expression for the damaged rotor. After obtaining the difference between the undamaged and damaged rotor impedance, a rotor damage detection method is proposed. This method can directly calculate the change of bending stiffness of the structural elements, it follows that the rotor damage can be effectively detected. Finally, a preset damage configuration is used for the numerical simulation. The result shows that the quantitative damage detection algorithm based on spectral element method and piezoelectric impedance proposed in this paper can identify the location and the severity of the damaged rotor accurately.

  3. Cascaded impedance networks for NPC inverter

    DEFF Research Database (Denmark)

    Li, Ding; Gao, Feng; Loh, Poh Chiang;

    2010-01-01

    would have a higher output voltage gain. It is anticipated that it would help the formed inverters find applications in photovoltaic and other renewable systems, where a high voltage gain is usually requested. Experimental testing has already been conducted and verifies the theory. ©2010 IEEE....... they are subject to the renewable sources. To date, three distinct types of impedance networks can be summarized for implementing a hybrid source impedance network, which can in principle be combined and cascaded before connected to a NPC inverter by proposed two ways. The resulting cascaded impedance network NPC...

  4. SPATIAL VARIABILITY OF PEDOZEMS MECHANICAL IMPEDANCE

    Directory of Open Access Journals (Sweden)

    Zhukov A.V.

    2013-04-01

    Full Text Available We studied the spatial variability of pedozem mechanical impedance in ResearchRemediation Center of the Dnipropetrovsk State Agrarian University in Ordzhonikidze. Thestatistical distribution of the soil mechanical impedance within the studied area is characterized by deviation from the normal law in 0–10 and 30–50 cm layers from the surface. 2D and 3D modeling shows the structural design of the soil as locations of high mechanical impedance which found in the soils with less hardness.

  5. Electrical Impedance Measurements of PZT Nanofiber Sensors

    Directory of Open Access Journals (Sweden)

    Richard Galos

    2017-01-01

    Full Text Available Electrical impedance measurements of PZT nanofiber sensors were performed using a variety of methods over a frequency spectrum ranging from DC to 1.8 GHz. The nanofibers formed by electrospinning with diameters ranging from 10 to 150 nm were collected and integrated into sensors using microfabrication techniques. Special matching circuits with ultrahigh input impedance were fabricated to produce low noise, measurable sensor outputs. Material properties including resistivity and dielectric constant are derived from the impedance measurements. The resulting material properties are also compared with those of individual nanofibers being tested using conductive AFM and Scanning Conductive Microscopy.

  6. Electrochemical Impedance Studies of SOFC Cathodes

    DEFF Research Database (Denmark)

    Hjelm, Johan; Søgaard, Martin; Wandel, Marie

    2007-01-01

    impedance of the cathode at intermediate operating temperatures. The perovskite is of the La-Sr-Co-Fe type. The EIS response of symmetrical cells with a thick (similar to 200 mu m) gadolinia doped ceria electrolyte was compared with the impedance contribution of the cathode of a full anode supported cell....... The full cells had a Ni-YSZ anode and anode support, a thin YSZ electrolyte, and a CGO barrier layer. The symmetric and full cell cathode responses were compared at open-circuit voltage. Humidified hydrogen was used as the fuel in the full cell measurements. Differential analysis of the impedance data...

  7. Wearable impedance monitoring system for dialysis patients.

    Science.gov (United States)

    Bonnet, S; Bourgerette, A; Gharbi, S; Rubeck, C; Arkouche, W; Massot, B; McAdams, E; Montalibet, A; Jallon, P

    2016-08-01

    This paper describes the development and the validation of a prototype wearable miniaturized impedance monitoring system for remote monitoring in home-based dialysis patients. This device is intended to assess the hydration status of dialysis patients using calf impedance measurements. The system is based on the low-power AD8302 component. The impedance calibration procedure is described together with the Cole parameter estimation and the hydric volume estimation. Results are given on a test cell to validate the design and on preliminary calf measurements showing Cole parameter variations during hemodialysis.

  8. Universal impedance fluctuations in wave chaotic systems.

    Science.gov (United States)

    Hemmady, Sameer; Zheng, Xing; Ott, Edward; Antonsen, Thomas M; Anlage, Steven M

    2005-01-14

    We experimentally investigate theoretical predictions of universal impedance fluctuations in wave chaotic systems using a microwave analog of a quantum chaotic infinite square well potential. We emphasize the use of the radiation impedance to remove the nonuniversal effects of the particular coupling between the outside world and the scatterer. Specific predictions that we test include the probability density functions (PDFs) of the real and imaginary parts of the universal impedance, the equality of the variances of these PDFs, and the dependence of these PDFs on a single loss parameter.

  9. On the applicability of fluidic flexible matrix composite variable impedance materials for prosthetic and orthotic devices

    Science.gov (United States)

    Philen, M.

    2009-10-01

    The applicability of variable impedance fluidic flexible matrix composites (F2MC) is investigated for development of prosthetic and orthotic devices. The F2MC material is an innovative combination of high performance composite tubes containing high bulk modulus fluids. The new material system can potentially achieve a change in stiffness of several orders of magnitude through valve control. The F2MC material system is investigated in this research through analytical studies for active impedance control for load transfer reduction in transtibial prosthetic sockets and impedance joint control for ankle-foot orthoses (AFO). Preliminary analysis results indicate that the variable modulus system can reduce the load transfer between the limb and transtibial socket and can provide impedance tailoring for improving foot-slap in an AFO.

  10. PREFACE: XV International Conference on Electrical Bio-Impedance (ICEBI) & XIV Conference on Electrical Impedance Tomography (EIT)

    Science.gov (United States)

    Pliquett, Uwe

    2013-04-01

    Over recent years advanced measurement methods have facilitated outstanding achievements not only in medical instrumentation but also in biotechnology. Impedance measurement is a simple and innocuous way to characterize materials. For more than 40 years biological materials, most of them based on cells, have been characterized by means of electrical impedance for quality control of agricultural products, monitoring of biotechnological or food processes or in health care. Although the list of possible applications is long, very few applications successfully entered the market before the turn of the century. This was, on the one hand, due to the low specificity of electrical impedance with respect to other material properties because it is influenced by multiple factors. On the other hand, equipment and methods for many potential applications were not available. With the appearance of microcontrollers that could be easily integrated in applications at the beginning of the 1980s, impedance measurement advanced as a valuable tool in process optimization and lab automation. However, established methods and data processing were mostly used in a new environment. This has changed significantly during the last 10 years with a dramatic growth of the market for medical instrumentation and also for biotechnological applications. Today, advanced process monitoring and control require fast and highly parallel electrical characterization which in turn yields incredible data volumes that must be handled in real time. Many newer developments require miniaturized but precise sensing methods which is one of the main parts of Lab-on-Chip technology. Moreover, biosensors increasingly use impedometric transducers, which are not compatible with the large expensive measurement devices that are common in the laboratory environment. Following the achievements in the field of bioimpedance measurement, we will now witness a dramatic development of new electrode structures and electronics

  11. Complex envelope control of pulsed accelerating fields in superconducting cavities

    CERN Document Server

    Czarski, T

    2010-01-01

    A digital control system for superconducting cavities of a linear accelerator is presented in this work. FPGA (Field Programmable Gate Arrays) based controller, managed by MATLAB, was developed to investigate a novel firmware implementation. The LLRF - Low Level Radio Frequency system for FLASH project in DESY is introduced. Essential modeling of a cavity resonator with signal and power analysis is considered as a key approach to the control methods. An electrical model is represented by the non-stationary state space equation for the complex envelope of the cavity voltage driven by the current generator and the beam loading. The electromechanical model of the superconducting cavity resonator including the Lorentz force detuning has been developed for a simulation purpose. The digital signal processing is proposed for the field vector detection. The field vector sum control is considered for multiple cavities driven by one klystron. An algebraic, complex domain model is proposed for the system analysis. The c...

  12. New Regularization Method in Electrical Impedance Tomography

    Institute of Scientific and Technical Information of China (English)

    侯卫东; 莫玉龙

    2002-01-01

    Image reconstruction in elecrical impedance tomography(EIT)is a highly ill-posed inverse problem,Regularization techniques must be used in order to solve the problem,In this paper,a new regularization method based on the spatial filtering theory is proposed.The new regularized reconstruction for EIT is independent of the estimation of impedance distribution,so it can be implemented more easily than the maxiumum a posteriori(MAP) method.The regularization level in our proposed method varies spatially so as to be suited to the correlation character of the object's impedance distribution.We implemented our regularization method with two dimensional computer simulations.The experimental results indicate that the quality of the reconstructed impedance images with the descibed regularization method based on spatial filtering theory is better than that with Tikhonov method.

  13. Impedance and collective effects in the LHC

    Energy Technology Data Exchange (ETDEWEB)

    Gareyte, J. [European Organization for Nuclear Research, Geneva (Switzerland)

    1996-08-01

    After a review of the main LHC parameters, and a brief description of the RF and vacuum systems, the coupling impedances of the main machine elements are given, as well as the resulting thresholds for instabilities. (author)

  14. Wave impedance retrieving via Bloch modes analysis

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, S.; Sukhorukov, A.;

    2011-01-01

    of the Bloch mode, respectively. Case studies prove that our ap-proach can determine material and wave effective parameters of lossy and lossless metamaterials. In some examples when the passivity is violated we made further analysis and showed that this is due to the failure of concept of impedance retrieving......-ciples violation, like antiresonance behaviour with Im(ε) mode analysis of periodic metamaterials to extract the dominating (fundamental) Bloch mode. Then it is possible to determine the Bloch and wave impedances by the surface and volume aver-aging of the electromagnetic field......The main bottleneck in the restoration of electromagnetic effective parameters is connected to the impedance retrieving. The S-parameters method gives the input (Bloch) impedance, which, being then used for permittivity and permeability determination, causes some fundamental physics prin...

  15. Thermal Impedance of Rectangular Microwave Oven Linings

    Institute of Scientific and Technical Information of China (English)

    SHIShang-zhao; XUFu-qiu; 等

    1996-01-01

    Amodel was preseted for calcultaing the thermal impedance of the insulation and refractory linings of rectangular microwave ovens,of which the oven cavity's dimensions are relatively small,while the linings re relatively thick.

  16. A Rotative Electrical Impedance Tomography Reconstruction System

    Energy Technology Data Exchange (ETDEWEB)

    Yu, F-M [St. John' s and St. Mary' s Institute of Technology, Department of computer science and information Engineering, 499, Sec. 4, Tam King Road Tamsui, Taipei, Taiwan (China); Huang, C-N [National Central University, Department of Electrical Engineering, No.300, Jungda Rd, Jhongli City, 320 Taoyuan, Taiwan (China); Chang, F-W [National Central University, Department of Electrical Engineering, No.300, Jungda Rd, Jhongli City, 320 Taoyuan, Taiwan (China); Chung, H-Y [National Central University, Department of Electrical Engineering, No.300, Jungda Rd, Jhongli City, 320 Taoyuan, Taiwan (China)

    2006-10-15

    Electrical impedance tomography (EIT) is a powerful tool for mapping the conductivity distribution of estimated objects. The EIT system is entirely implemented by electrical technique, so it is a relatively cheap system and data can be collected very rapidly. But it has few commercially medical EIT systems available. This is because impedance image unable to achieve the essential spatial resolution and this technique has an intrinsically poor signal to noise ratio. In this paper, we have developed a high performance rotative EIT system (REIT) for expanding the independent measurements. By rotate the electrodes successive, REIT could change the position of electrodes and acquire more measurement data. This rotative measurement method not only can increase the resolution of impedance images, but also reduce the complexity of measurement system. We hope the improvement of REIT will bring some help in electrical impedance tomography.

  17. Modeling degradation in SOEC impedance spectra

    DEFF Research Database (Denmark)

    Jensen, Søren Højgaard; Hauch, Anne; Knibbe, Ruth;

    2013-01-01

    Solid oxide cell (SOC) performance is limited by various processes. One way to investigate these processes is by electrochemical impedance spectroscopy. In order to quantify and characterize the processes, an equivalent circuit can be used to model the SOC impedance spectra (IS). Unfortunately......, the optimal equivalent circuit is often unknown and to complicate matters further, several processes contribute to the SOC impedance - making detailed process characterization difficult. In this work we analyze and model a series of IS measured during steam electrolysis operation of an SOC. During testing......, degradation is only observed in the Ni/YSZ electrode and not in the electrolyte or the LSM/YSZ electrode. A batch fit of the differences between the IS shows that a modified Gerischer element provides a better fit to the Ni/YSZ electrode impedance than the frequently used RQ element - albeit neither...

  18. The task-orientated control system of a dexterous robot hand with a multi-fingered spatial coordinating impedance control%面向任务的机器人灵巧手控制系统及多指空间协调阻抗控制

    Institute of Scientific and Technical Information of China (English)

    陈兆芃; 金明河; 樊绍巍; 刘伊威; 吴克; 姜力; 刘宏

    2012-01-01

    为提高多指灵巧手的控制和操作性能,提出了基于集中控制-分层处理的DLR/HIT Ⅱ机器人灵巧手实时控制系统结构,并建立了基于Simulink/QNX的实时控制平台和嵌入式驱动控制层,极大地简化了高集成度机电一体化灵巧手的控制器设计过程,并实现灵巧手在多自由度仿机器人上的无缝连接,进行了多指灵巧手空间协调阻抗控制的研究,基于手指指尖位置建立了适用于任意手指数目n的机器人灵巧手物体空间坐标系,并基于六维空间虚拟弹簧的阻抗思想和关节力矩反馈实现了以被抓取物体位置和姿态为控制目标的多指灵巧手空间协调阻抗控制.在基于Simulink/QNX的实时控制平台上对DLR/HIT Ⅱ灵巧手进行了空间协调阻抗控制实验,实验结果表明了灵巧手控制软硬件系统和控制策略的有效性和稳定性.在未降低灵巧手自由度的前提下,将DLR/HIT Ⅱ多指灵巧手协调抓取操作的控制输入量由30个减为6个,为提高抓取规划算法效率提供了稳定高效的新型控制策略.%In order to improve the control and manipulation performance, this paper presented a centralized-eontroller/ decentralized-data-processing real time control architecture for the DLR/HIT II dexterous robot hand, and established a Simuhrik/QNX-based real time control platform along with an embedded drive control layer. These improvements significantly simplified the development procedure of a controller for a highly integrated mechatronic robot hand, and provided a seamless interface between the dexterous robot hand arid multi-DoF humanoid robots. By utilizing the positions of fingertips , this paper proposed an object level frame for an n -fingered robot hand. In order to control the position and pose of the object being grabbed, a spatial coordination impedance controller has been implemented based on 6-DoF spatial virtual spring stiffness and joint torque feedback. The experiments

  19. Analysis of impedance measurements of a suspension of microcapsules using a variable length impedance measurement cell

    Directory of Open Access Journals (Sweden)

    Dejan Krizaj

    2012-10-01

    Full Text Available Electrical impedance measurements of the suspensions have to take into account the double layer impedance that is due to a very thin charged layer formed at the electrode-electrolite interface. A dedicated measuring cell that enables variation of the distance between the electrodes was developed for investigation of electrical properties of suspensions using two electrode impedance measurements. By varying the distance between the electrodes it is possible to separate the double layer and the suspension impedance from the measured data. From measured and extracted impedances electrical lumped models have been developed. The error of non inclusion of the double layer impedance has been analyzed. The error depends on the frequency of the measurements as well as on the distance between the electrodes.

  20. Tunable sound transmission at an impedance-mismatched fluidic interface assisted by a composite waveguide

    Science.gov (United States)

    Zhang, Hui; Wei, Zhi; Fan, Li; Qu, Jianmin; Zhang, Shu-Yi

    2016-10-01

    We report a composite waveguide fabricated by attaching a coupling aperture to a waveguide. The acoustic impedance of the composite waveguide can be regulated by merely controlling its coupling vibrations, depending on its structure size. By changing the size to adjust the acoustic impedance of the composite waveguide at an impedance-mismatched fluidic interface, tunable sound transmission at the desired frequencies is achieved. The reported composite waveguide provides a new method for sound regulation at a mismatched fluidic interface and has extensive frequency hopping and frequency agility applications in air-water sound communication.

  1. Effect of shear on duct wall impedance.

    Science.gov (United States)

    Goldstein, M.; Rice, E.

    1973-01-01

    The solution to the equation governing the propagation of sound in a uniform shear layer is expressed in terms of parabolic cylinder functions. This result is used to develop a closed-form solution for acoustic wall impedance which accounts for both the duct liner and the presence of a boundary layer in the duct. The effective wall impedance can then be used as the boundary condition for the much simpler problem of sound propagation in uniform flow.

  2. CSR Impedance for Non-Ultrarelativistic Beams

    Energy Technology Data Exchange (ETDEWEB)

    Li, Rui [Jefferson Lab., Newport News, VA (United States); Tsai, Cheng Y. [Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States); Jefferson Lab., Newport News, VA (United States)

    2015-09-01

    For the analysis of the coherent synchrotron radiation (CSR)-induced microbunching gain in the low energy regime, such as when a high-brightness electron beam is transported through a low-energy merger in an energy-recovery linac (ERL) design, it is necessary to extend the CSR impedance expression in the ultrarelativistic limit to the non-ultrarelativistic regime. This paper presents our analysis of CSR impedance for general beam energies.

  3. Design of an impedance matching acoustic bend

    OpenAIRE

    Yang, Yuzhen; Jia, Han; Lu, Wenjia; Sun, Zhaoyong; Yang, Jun

    2017-01-01

    We propose the design of an impedance matching acoustic bend in this article. The bending structure is composed of sub-wavelength unit cells with perforated plates and side pipes, whose mass density and bulk modulus can be tuned simultaneously. So the refraction index and the impedance of the acoustic bend can be modulated simultaneously to guarantee both the bending effect and the high transmission. The simulation results of sound pressure field distribution show that the bending effect of t...

  4. An integrated microfluidic analysis microsystems with bacterial capture enrichment and in-situ impedance detection

    Science.gov (United States)

    Liu, Hai-Tao; Wen, Zhi-Yu; Xu, Yi; Shang, Zheng-Guo; Peng, Jin-Lan; Tian, Peng

    2017-09-01

    In this paper, an integrated microfluidic analysis microsystems with bacterial capture enrichment and in-situ impedance detection was purposed based on microfluidic chips dielectrophoresis technique and electrochemical impedance detection principle. The microsystems include microfluidic chip, main control module, and drive and control module, and signal detection and processing modulet and result display unit. The main control module produce the work sequence of impedance detection system parts and achieve data communication functions, the drive and control circuit generate AC signal which amplitude and frequency adjustable, and it was applied on the foodborne pathogens impedance analysis microsystems to realize the capture enrichment and impedance detection. The signal detection and processing circuit translate the current signal into impendence of bacteria, and transfer to computer, the last detection result is displayed on the computer. The experiment sample was prepared by adding Escherichia coli standard sample into chicken sample solution, and the samples were tested on the dielectrophoresis chip capture enrichment and in-situ impedance detection microsystems with micro-array electrode microfluidic chips. The experiments show that the Escherichia coli detection limit of microsystems is 5 × 104 CFU/mL and the detection time is within 6 min in the optimization of voltage detection 10 V and detection frequency 500 KHz operating conditions. The integrated microfluidic analysis microsystems laid the solid foundation for rapid real-time in-situ detection of bacteria.

  5. DEMONSTRATION OF AN ATCA BASED RF CONTROL SYSTEM AT FLASH

    CERN Document Server

    Simrock, S N; Jezynski, T; Koprek, W; Butkowski, L; Jablonski, G W; Jalmuzna, W; Makowski, D R; Piotrowski, A; Czuba, K

    2009-01-01

    Future rf control systems will require simultaneous data acquisition of up to 100 fast ADC channels at sampling rates of around 100 MHz and real time signal processing within a few hundred nanoseconds. At the same time the standardization of Low-Level RF systems are common objectives for all laboratories for cost reduction, performance optimization and machine reliability. Also desirable are modularity and scalability of the design as well as compatibility with accelerator instrumentation needs including the control system. All these requirements can be fulfilled with the new telecommunication standard ATCA when adopted to the domain of instrumentation. We describe the architecture and design of an ATCA based LLRF system for the European XFEL. The operation of a prototype capable of controlling the vectorsum of 24-cavities and providing measurements of forward and reflected power are presented.

  6. Probe impedance measurements for millimeter-wave integrated horn antennas

    Science.gov (United States)

    Guo, Yong; Chiao, Jung-Chih; Potter, Kent A.; Rutledge, David B.

    1993-01-01

    In order to achieve an impedance-matched millimeter-wave integrated horn antenna mixer array, the characteristics of the antenna probes inside the horn must be known. This paper describes impedance measurements for various probes in low-frequency model horns of two different types: (1) a 3 x 3 array made of aluminum by electric discharge machining and (2) a half horn made of copper sheet placed on a big copper-clad circuit board that was used as an image plane. The results of measurements indicate that the presence of the horn increases the effective length of the probe element, in agreement with reports of Guo et al. (1991) and theoretical analysis of Eleftheriades et al. (1991). It was also found that the resonant frequencies can be controlled by changing the length of the probes or by loading the probes.

  7. Tunable Versatile High Input Impedance Voltage-Mode Universal Biquadratic Filter Based on DDCCs

    Directory of Open Access Journals (Sweden)

    Jiun-Wei Horng

    2012-12-01

    Full Text Available A high input impedance voltage-mode universal biquadratic filter with three input terminals and seven output terminals is presented. The proposed circuit uses three differential difference current conveyors (DDCCs, four resistors and two grounded capacitors. The proposed circuit can realize all the standard filter functions, namely, lowpass, bandpass, highpass, notch and allpass, simultaneously. The proposed circuit offers the features of high input impedance, using only grounded capacitors, and orthogonal controllability of resonance angular frequency and quality factor.

  8. Electromagnetic Wave Scattering By the Coated Impedance Cylinder

    Directory of Open Access Journals (Sweden)

    V.I. Vyunnik

    2010-01-01

    Full Text Available In this work the boundary conditions for the impedance circular cylinder coated by a low contrast dielectric thin layer are derived. Expression for the reduced impedance of the cylinder is obtained. Conditions and applicability limits of the proposed approach are defined. Influence of the coating impedance on the reduced impedance of the cylinder is investigated.

  9. Development of automatic impedance matching system for hyperthermia treatment using resonant cavity applicator.

    Science.gov (United States)

    Shindo, Y; Kato, K; Hirashima, T; Yabuhara, T

    2008-01-01

    In this paper, we discuss a new system to make impedance matching automatically for a re-entrant resonant cavity applicator for brain tumor hyperthermia treatment non-invasively. We have already discussed about the effectiveness of the heating method using manual type impedance matching controller, with experiments of heating an agar phantom and computer simulations. However, it becomes difficult to perform an accurate impedance matching as resonant frequency becomes high. Here, in order to make a more accurate impedance matching, we developed the automatic impedance matching system (AIMS). We noticed that the reflected power was generated when the impedance matching was not complete. In this system, therefore, to reduce the reflected power fed back, the stepping motor to turn the dial of variable capacitors is controlled by developed software. To evaluate the developed AIMS, the experiments of heating the agar phantom were performed. From these results, we found that the temperature rise of the agar phantom by using AIMS was about 180% of using manual type controller under the same heating condition. It was found that the proposed system was very effective for hyperthermia treatment using resonant cavity applicator even when the resonant frequency was high.

  10. Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Haipeng [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Plawski, Tomasz E. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Rimmer, Robert A. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Dudas, A. [Muons Inc., Batavia, IL (United States); Neubauer, M. L. [Muons Inc., Batavia, IL (United States)

    2016-06-01

    Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve, output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen’s model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper.

  11. Spatially resolved voltage, current and electrochemical impedance spectroscopy measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gerteisen, D.; Kurz, T.; Schwager, M.; Hebling, C. [Fraunhofer Institute for Solar Energy Systems ISE, Freiburg im Breisgau (Germany); Merida, W. [Clean Energy Research Centre, University of British Columbia, Vancouver, BC (Canada); Lupotto, P. [Materials Mates Italia, Milano (Italy)

    2011-04-15

    In this work a 50-channel characterisation system for PEMFCs is presented. The system is capable of traditional electrochemical measurements (e.g. staircase voltammetry, chronoamperometry and cyclic voltammetry), and concurrent EIS measurements. Unlike previous implementations, this system relies on dedicated potentiostats for current and voltage control, and independent frequency response analysers (FRAs) at each channel. Segmented fuel cell hardware is used to illustrate the system's flexibility and capabilities. The results here include steady-state data for cell characterisation under galvanostatic and potentiostatic control as well as spatially resolved impedance spectra. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  12. VISUALIZATION OF BIOLOGICAL TISSUE IMPEDANCE PARAMETERS

    Directory of Open Access Journals (Sweden)

    V. I. Bankov

    2016-01-01

    Full Text Available Objective. Investigation the opportunity for measurement of biological tissue impedance to visualize its parameters.Materials and methods. Studies were undertook on the experimental facility, consists of registrating measuring cell, constructed from flat inductors system, formed in oscillatory circuit, herewith investigated biological tissue is the part of this oscillatory circuit. An excitation of oscillatory circuit fulfilled by means of exciter inductor which forms impulse complex modulated electromagnetic field (ICM EMF. The measurement process and visualizations provided by set of certificated instruments: a digital oscillograph AKTAKOM ADS-2221MV, a digital generator АКТАКОМ AWG-4150 (both with software and a gauge RLC E7-22. Comparative dynamic studies of fixed volume and weight pig’s blood, adipose tissue, muscular tissue impedance were conducted by contact versus contactless methods. Contactless method in contrast to contact method gives opportunity to obtain the real morphological visualization of biological tissue irrespective of their nature.Results. Comparison of contact and contactless methods of impedance measurement shows that the inductance to capacitance ratio X(L / X(C was equal: 17 – for muscular tissue, 4 – for blood, 1 – for adipose tissue. It demonstrates the technical correspondence of both impedance registration methods. If propose the base relevance of X (L and X (C parameters for biological tissue impedance so contactless measurement method for sure shows insulating properties of adipose tissue and high conductivity for blood and muscular tissue in fixed volume-weight parameters. Registration of biological tissue impedance complex parameters by contactless method with the help of induced ICM EMF in fixed volume of biological tissue uncovers the most important informative volumes to characterize morphofunctional condition of biological tissue namely X (L / X (C.Conclusion. Contactless method of biological

  13. Analysis on electromagnetic scattering by a wedge with impedance faces under exact impedance boundary

    Institute of Scientific and Technical Information of China (English)

    吴良超; 汪茂光

    1995-01-01

    Under the exact impedance boundary condition (EIBC), by using wave equations and the longitudinal field method, the electromagnetic scattenng by an impedance wedge has been analysed in detail, following the Maliuzhinets approach, and the uniform diffraction coefficient of the diffracted field has been presented.

  14. A novel method for real-time skin impedance measurement during radiofrequency skin tightening treatments.

    Science.gov (United States)

    Harth, Yoram; Lischinsky, Daniel

    2011-03-01

    The thermal effects of monopolar and bipolar radiofrequency (RF) have been proven to be beneficial in skin tightening. Nevertheless, these effects were frequently partial or unpredictable because of the uncontrolled nature of monopolar or unipolar RF and the superficial nature of energy flow for bipolar or tripolar configurations. One of the hypotheses for lack or predictability of efficacy of the first-generation RF therapy skin tightening systems is lack of adaptation of delivered power to differences in individual skin impedance. A novel multisource phase-controlled system was used (1 MHz, power range 0-65 W) for treatment and real-time skin impedance measurements in 24 patients (EndyMed PRO™; EndyMed, Cesarea, Israel). This system allows continuous real-time measurement of skin impedance delivering constant energy to the patient skin independent of changes in its impedance. More than 6000 unique skin impedance measurements on 22 patients showed an average session impedance range was 215-584 Ohm with an average of 369 Ohm (standard deviation of 49 Ohm). Analyzing individual pulses (total of 600 readings) showed a significant decrease in impedance during the pulse. These findings validate the expected differences in skin impedance between individual patients and in the same patients during the treatment pulse. Clinical study on 30 patients with facial skin aging using the device has shown high predictability of efficacy (86.7% of patients had good results or better at 3 months' follow-up [decrease of 2 or more grades in Fitzpatrick's wrinkle scale]). The real-time customization of energy according to skin impedance allows a significantly more accurate and safe method of nonablative skin tightening with more consistent and predictable results. © 2011 Wiley Periodicals, Inc.

  15. Noninvasive surface measurement of corrosion impedance of reinforcing bar in concrete - part 1: experimental results

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jieying; Monteiro, Paulo J.M.; Morrison, H. Frank

    2000-11-01

    The corrosion state of a reinforcing steel bar in concrete can be characterized by the electrical impedance of the interface between the steel bar and the concrete. The experimental part of this study, has shown that changes in the interfacial impedance that are diagnostic of the rate and extent of the corrosion can be measured indirectly with an array of current and voltage electrodes on the concrete surface. The measured impedance, however depends on the electrical resistivity of the concrete, and the depth and diameter of the steel reinforcing bar as well as the interfacial properties. To relate the measured impedance directly to the interfacial properties, a closed-form solution to the governing Poisson's equation was developed and programmed for the potentials from arbitrary, current sources in the vicinity of the reinforcing bar. The solution uses an impedance boundary, condition for the complex impedance at the steel-concrete interface. The response of an arbitrary corrosion state can be simulated in this model by embedding the appropriate complex, frequency-dependent impedance at the interface and computing the voltage/current response that would be measured for an arbitrary placement of electrodes on the concrete surface. To simulate the experimental findings, this paper presents the modeling results by various interfacial impedances but constant concrete resistivity and constant geometry of the steel reinforcing bar This simulation confirms that important parameters of the interfacial impedance controlling corrosion kinetics such as polarization resistance and double layer capacitance are clearly, observed in the measured surface data. [References: 10

  16. Noninvasive surface measurement of corrosion impedance of reinforcing bar in concrete - part 2: forward modeling

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Jieying; Monteiro, Paulo J. M.; Morrison, H. Frank

    2002-01-02

    The corrosion state of a reinforcing steel bar in concrete can be characterized by the electrical impedance of the interface between the steel bar and the concrete. The experimental part of this study, has shown that changes in the interfacial impedance that are diagnostic of the rate and extent of the corrosion can be measured indirectly with an array of current and voltage electrodes on the concrete surface. The measured impedance, however depends on the electrical resistivity of the concrete, and the depth and diameter of the steel reinforcing bar as well as the interfacial properties. To relate the measured impedance directly to the interfacial properties, a closed-form solution to the governing Poisson's equation was developed and programmed for the potentials from arbitrary, current sources in the vicinity of the reinforcing bar. The solution uses an impedance boundary, condition for the complex impedance at the steel-concrete interface. The response of an arbitrary corrosion state can be simulated in this model by embedding the appropriate complex, frequency-dependent impedance at the interface and computing the voltage/current response that would be measured for an arbitrary placement of electrodes on the concrete surface. To simulate the experimental findings, this paper presents the modeling results by various interfacial impedances but constant concrete resistivity and constant geometry of the steel reinforcing bar. This simulation confirms that important parameters of the interfacial impedance controlling corrosion kinetics such as polarization resistance and double layer capacitance are clearly, observed in the measured surface data. [References: 10

  17. Resonant impedance matchers for Mario Schenberg detector

    Energy Technology Data Exchange (ETDEWEB)

    Frajuca, Carlos; Bortoli, Fabio S. [Centro Federal de Educacao Tecnologica de Sao Paulo, SP (Brazil)

    2006-07-01

    'Mario Schenberg' is a spherical resonant-mass gravitational wave (GW) detector that will be part of a GW detection array of two detectors, the other one is been built in The Netherlands. Their resonant frequencies will be around 3.2 kHz with a bandwidth of about 200 Hz. This range of frequencies is new in a field where the typical frequencies lay below 1 kHz, making the transducer development much more complex. Some studies indicated that using low mass mechanical resonators (used for impedance matching to the parametric transducer, in a cold damping regime), allow the detector to reach the standard quantum limit. In this work we describe the study of mechanical impedance matcher resonators used to obtain a better coupling between the sphere and the transducers and keeping the same calibration for all transducers, this has been show to be not a easy task since the differential motions of the sphere surface propagates to the motions of the resonant mechanical impedance matchers, when it can be done then the next step is to calculate the effective mass of the resonating mechanical impedance matcher and then, calculate the detector sensitivity, this is also complicated because there is a spread in the resonant mechanical impedance matcher frequencies. (author)

  18. Resonant impedance of bellows above cutoff

    Energy Technology Data Exchange (ETDEWEB)

    Krinsky, S

    1980-01-01

    The perturbation method of Chatard-Moulin and Papiernik is used to calculate the longitudinal and transverse impedances, Z(..omega..) and Z/sub perpendicular/(..omega..), of a bellows. The bellows shape is defined by its radius a(z) = a (1 + epsilons(z)), where a is the mean radius, epsilon a small parameter, and s(z) describes the convolution of the bellows. A finite wall conductivity is considered and the resonant contribution to the impedance above the cutoff frequency of the unperturbed chamber is determined, obtaining analytic approximations to the resonant frequencies, quality factors, and shunt impedances. The relation Z/sub perpendicular/(..omega..) = (2c/a/sup 2/)Z(..omega..)/..omega.., of course, does not hold as an identity, but it is found to be a useful relation for the shunt impedances, holding exactly for one family of transverse modes and providing an upper bound on the shunt impedances of the second set of transverse modes.

  19. Assessing heat treatment of chicken breast cuts by impedance spectroscopy.

    Science.gov (United States)

    Schmidt, Franciny C; Fuentes, Ana; Masot, Rafael; Alcañiz, Miguel; Laurindo, João B; Barat, José M

    2017-03-01

    The aim of this work was to develop a new system based on impedance spectroscopy to assess the heat treatment of previously cooked chicken meat by two experiments; in the first, samples were cooked at different temperatures (from 60 to 90 ℃) until core temperature of the meat reached the water bath temperature. In the second approach, temperature was 80 ℃ and the samples were cooked for different times (from 5 to 55 min). Impedance was measured once samples had cooled. The examined processing parameters were the maximum temperature reached in thermal centre of the samples, weight loss, moisture and the integral of the temperature profile during the cooking-cooling process. The correlation between the processing parameters and impedance was studied by partial least square regressions. The models were able to predict the studied parameters. Our results are essential for developing a new system to control the technological, sensory and safety aspects of cooked meat products on the whole meat processing line.

  20. Copper Phthalocyanine Thin Film Morphology Impact on Impedance Spectrum

    Science.gov (United States)

    Robinson, Kyle; Gredig, Thomas

    2012-11-01

    Copper phthlacyanine thin films play an important role as the active layer in gas sensors, organic solar cells, and organic field-effect transistors. The surface morphology of such thin films can be controlled via modification of thermal deposition parameters. Thin films were deposited onto platinum interdigitated electrodes for impedance measurements to study the effect of structure on charge transport. The average grain size increases and changes from α- and β-phase for samples deposited in the temperature range of 295-534 K. AC measurements in the temperature range of 295-385 K reveal relaxation peaks in the impedance spectra. From this spectrum, essential properties are retrieved, such as relaxation times and effective capacities, and correlated with the film morphology. Subject to both photo- and 5-day-dark current trials, photodecay rates are extracted via effective impedance circuit analysis using a phenomenological model that includes contributions from the grain boundary and the bulk part of the grain. Results indicate that the resistance contribution of low frequency relaxation peaks decrease while approaching the phase transition temperature, and vice versa for capacitance. We attribute the low-frequency peaks to grain boundaries, which are reduced in high temperature deposited samples. Hyper β-phase deposition temperatures show a sudden rise in resistance and lower capacitance due to increased roughness of samples.

  1. 基于滑模控制的谐振阻抗型混合有源滤波系统控制技术%Control Technique of the Resonant Impedance Type Hybrid Active Power Filter Based on Sliding Mode Control

    Institute of Scientific and Technical Information of China (English)

    梁应昌

    2015-01-01

    基于滑模控制原理,针对矿用谐振阻抗型混合有源滤波系统( RITHAPF)控制技术进行深入研究,并对电网进行无功补偿和谐波抑制。利用开关函数建模法进行系统建模,给出RITHAPF的数学模型。通过对RITHAPF的等效模型的分析推导,提出了RITHAPF系统的收敛和稳定判据。结合离散指数趋近律对离散滑模控制的影响,将连续系统的指数趋近律方法推广到离散系统,证明离散指数趋近律滑模控制对系统摄动和外界干扰依然具有鲁棒性。进一步根据有源电力滤波器的离散数学模型,设计滑模离散数学模型。基于趋近律离散滑模变结构控制设计有源部分的电流跟踪控制器。结果表明,采用滑模控制的谐振阻抗型混合有源滤波器对矿用直流提升系统6 kV母线的无功功率和谐波电流补偿效果良好。%Based on principle of sliding mode control,the mine-used resonant impedance type hybrid active power filter system ( RITHAPF) control technology was further researched,and reactive power compensation and harmonic suppression on power grid were made. The switching function modeling method was adopted to make modeling and propose the mathematical model of RITHAPF. Through the derivation of RITHAPF equivalent model,a convergence and stability criterion was put for-ward for RITHAPF system. Combining the influence of discrete index reaching law on discrete sliding mode control,the reac-hing law index of the continuous system was extended to the discrete system,to prove that influence of the discrete index on the system perturbations and external disturbances is still robust. Furthermore,according to the discrete mathematical model of ac-tive power filter,the synovial discrete mathematical model is given. The active part current tracking controller was designed based on the reaching law of the discrete sliding mode control. The simulation results showed that the resonant impedance type

  2. Doubly Fed Induction Generator System Resonance Active Damping through Stator Virtual Impedance

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The penetration of wind power has been increasing in the past few decades all over the world. Under certain non-ideal situations where the wind power generation system is connected to the weak grid, the Doubly Fed Induction Generator (DFIG) based wind power generation system may suffer High...... Frequency Resonance (HFR) due to the impedance interaction between the DFIG system and the weak grid network whose impedance is comparative large. Thus, it is important to implement an active damping for the HFR in order to ensure a safe and reliable operation of both the DFIG system and the grid connected...... converters/loads. This paper analyzes and explains first the HFR phenomenon between the DFIG system and a parallel compensated weak network (series RL + shunt C). Then on the basis of the DFIG system impedance modeling, an active damping control strategy is introduced by inserting a virtual impedance...

  3. Impedance-Based High Frequency Resonance Analysis of DFIG System in Weak Grids

    DEFF Research Database (Denmark)

    Song, Yipeng; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The impedance-based model of Doubly Fed Induction Generator (DFIG) systems, including the rotor part (Rotor Side Converter (RSC) and induction machine), and the grid part (Grid Side Converter (GSC) and its output filter), has been developed for analysis and mitigation of the Sub- Synchronous...... Resonance (SSR). However, the High Frequency Resonance (HFR) of DFIG systems due to the impedance interaction between DFIG system and parallel compensated weak network is often overlooked. This paper thus investigates the impedance characteristics of DFIG systems for the analysis of HFR. The influences...... of the rotor speed variation, the machine mutual inductance and the digital control delay are evaluated. Two resonances phenomena are revealed, i.e., 1) the series HFR between the DFIG system and weak power grid; 2) the parallel HFR between the rotor part and the grid part of DFIG system. The impedance...

  4. Experimental investigation of microwave interaction with magnetoplasma in miniature multipolar configuration using impedance measurements

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Indranuj, E-mail: indranuj@aees.kyushu-u.ac.jp; Toyoda, Yuji; Yamamoto, Naoji; Nakashima, Hideki [Department of Advanced Energy Engineering Science, Kyushu University, Kasuga 816-8580 (Japan)

    2014-09-15

    A miniature microwave plasma source employing both radial and axial magnetic fields for plasma confinement has been developed for micro-propulsion applications. Plasma is initiated by launching microwaves via a short monopole antenna to circumvent geometrical cutoff limitations. The amplitude and phase of the forward and reflected microwave power is measured to obtain the complex reflection coefficient from which the equivalent impedance of the plasma source is determined. Effect of critical plasma density condition is reflected in the measurements and provides insight into the working of the miniature plasma source. A basic impedance calculation model is developed to help in understanding the experimental observations. From experiment and theory, it is seen that the equivalent impedance magnitude is controlled by the coaxial discharge boundary conditions, and the phase is influenced primarily by the plasma immersed antenna impedance.

  5. Electronically Tunable Impedance-Matching Networks for Intelligent RF Power Amplifiers

    Directory of Open Access Journals (Sweden)

    Liang Li

    2013-11-01

    Full Text Available This paper presents the simulation and optimization design of the electronically tunable impedance-matching networks for intelligent RF power amplifiers in a cognitive radio system. Reconfigurable elements, such as varactors and RF switches are utilized to achieve the dynamic impedance matching both in the input and output matching circuit, providing coarse and fine tuning of the target impedances with low loss and excellent impedance coverage from 500MHz to 800MHz. The topology of varactor model is illustrated to ensure the precision of simulation. In addition, high-precision bias voltage controlling system is designed to improve the nonlinear problem caused by the varactor. The simulation results demonstrate the excellent performance of the tunable networks, satisfying the requirement of the cognitive radio systems.  

  6. Plasma Diagnostics by Antenna Impedance Measurements

    Science.gov (United States)

    Swenson, C. M.; Baker, K. D.; Pound, E.; Jensen, M. D.

    1993-01-01

    The impedance of an electrically short antenna immersed in a plasma provides an excellent in situ diagnostic tool for electron density and other plasma parameters. By electrically short we mean that the wavelength of the free-space electromagnetic wave that would be excited at the driving frequency is much longer than the physical size of the antenna. Probes using this impedance technique have had a long history with sounding rockets and satellites, stretching back to the early 1960s. This active technique could provide information on composition and temperature of plasmas for comet or planetary missions. Advantages of the impedance probe technique are discussed and two classes of instruments built and flown by SDL-USU for determining electron density (the capacitance and plasma frequency probes) are described.

  7. Impedance properties of circular microstrip antenna

    Science.gov (United States)

    Deshpande, M. D.; Bailey, M. C.

    1983-01-01

    A moment method solution to the input impedance of a circular microstrip antenna excited by either a microstrip feed or a coaxial probe is presented. Using the exact dyadic Green's function and the Fourier transform the problem is formulated in terms of Richmond's reaction integral equation from which the unknown patch current can be solved for. The patch current is expanded in terms of regular surface patch modes and an attachment mode (for probe excited case) which insures continuity of the current at probe/patch junction, proper polarization and p-dependance of patch current in the vicinity of the probe. The input impedance of a circular microstrip antenna is computed and compared with earlier results. Effect of attachment mode on the input impedance is also discussed.

  8. Impedance plethysmographic observations in thoracic outlet syndrome.

    Directory of Open Access Journals (Sweden)

    Nerurkar S

    1990-07-01

    Full Text Available Forty patients with symptoms of neuro-vascular compression in the upper extremities were subjected to impedance plethysmographic study using Parulkar′s method. Two patients recorded decreased blood flow (BFI in supine position and were diagnosed as having partial occlusion at subclavian level. Sixteen of the patients recorded decreased BFI on 90 degrees abduction and hyper-abduction. Twelve of these patients had radiological evidence of anomalous cervicle ribs. In remaining four patients extrinsic impression on the subclavian artery due to fibrous deposits was confirmed by arteriography. Remaining 22 patients recorded normal impedance plethysmograms. Impedance plethysmography thus provided a non-invasive modality for confirmation of vascular compression in thoracic outlet syndrome.

  9. Bench Measurements of Low Frequency Transverse Impedance

    CERN Document Server

    Caspers, Friedhelm; Mostacci, A

    2003-01-01

    For frequencies below 10 MHz the classical two wire transmission line method is subject to difficulties in sensitivity and measurement uncertainties. Thus for evaluation of the low frequency transverse impedance properties of the LHC dump kicker a modified version of the two wire transmission line has been used. It consists, in the present case, of a 10 turn loop of approximately 1 meter length and 2 cm width. The change of input impedance of the loop is measured as a function of the surroundings and by using a proper reference (metallic beampipe) these changes are converted into a meaningful transverse beam coupling impedance. Measurements of several calibration objects have shown close agreement with theoretical results.

  10. ac impedance of the carbon monofluoride electrode

    Science.gov (United States)

    Suchanski, M. R.

    1985-09-01

    The ac impedance of carbon monofluoride (CF) half-cells and Li/CF batteries that contain 1M LiBF4/4-butyrolactone electrolyte was measured as a function of state of charge. The nonfaradaic components of the CF half-cell impedance were resolved with the aid of a one-dimensional macroscopic treatment of a porous electrode. The values of the nonfaradaic components and their variation with charge withdrawn provide information concerning the nature of cathode discharge products, the degree of tortuosity in the cathode and separator matrices, and the cathode failure mechanism. The CF electrode capacitance, as measured by the low frequency quadrature impedance, can serve as a semiquantitative measure of battery state of charge under certain conditions.

  11. Wavelet analysis of the impedance cardiogram waveforms

    Science.gov (United States)

    Podtaev, S.; Stepanov, R.; Dumler, A.; Chugainov, S.; Tziberkin, K.

    2012-12-01

    Impedance cardiography has been used for diagnosing atrial and ventricular dysfunctions, valve disorders, aortic stenosis, and vascular diseases. Almost all the applications of impedance cardiography require determination of some of the characteristic points of the ICG waveform. The ICG waveform has a set of characteristic points known as A, B, E ((dZ/dt)max) X, Y, O and Z. These points are related to distinct physiological events in the cardiac cycle. Objective of this work is an approbation of a new method of processing and interpretation of the impedance cardiogram waveforms using wavelet analysis. A method of computer thoracic tetrapolar polyrheocardiography is used for hemodynamic registrations. Use of original wavelet differentiation algorithm allows combining filtration and calculation of the derivatives of rheocardiogram. The proposed approach can be used in clinical practice for early diagnostics of cardiovascular system remodelling in the course of different pathologies.

  12. Complex impedance studies of lithium iodine batteries

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, C.L.; Skarstad, P.M. (Promeon Division Medtronic, Inc. Minneapolis, MN (US))

    1990-08-01

    Complex impedance spectra of conductivity cells containing iodine/poly-2-vinylpyridine cathode material were taken by two- and four-probe techniques. The impedance spectra contain a current-independent bulk resistance in series with a current-dependent interfacial resistance. The current-dependent interfacial resistance has the characteristics expected of a charge-transfer resistance. Moreover, electronically blocked (lithium/lithium iodide) electrodes give the same result as non-blocked (stainless steel) electrodes. This is exactly what would be expected if the medium were an ionic conductor. Complex impedance spectra of lithium/iodine batteries show additional structure, as might be expected, but are consistent with results from the conductivity cells.

  13. Local impedance imaging of boron-doped polycrystalline diamond thin films

    Energy Technology Data Exchange (ETDEWEB)

    Zieliński, A.; Ryl, J.; Burczyk, L.; Darowicki, K. [Department of Electrochemistry, Corrosion and Material Engineering, Gdansk University of Technology, 11/12 Narutowicza St., 80-233 Gdansk (Poland); Bogdanowicz, R., E-mail: rbogdan@eti.pg.gda.pl [Department of Metrology and Optoelectronics, Faculty of Electronics, Telecommunications and Informatics, Gdansk University of Technology, 11/12 G. Narutowicza St., 80-233 Gdansk (Poland)

    2014-09-29

    Local impedance imaging (LII) was used to visualise surficial deviations of AC impedances in polycrystalline boron-doped diamond (BDD). The BDD thin film electrodes were deposited onto the highly doped silicon substrates via microwave plasma-enhanced CVD. The studied boron dopant concentrations, controlled by the [B]/[C] ratio in plasma, ranged from 1 × 10{sup 16} to 2 × 10{sup 21} atoms cm{sup −3}. The BDD films displayed microcrystalline structure, while the average size of crystallites decreased from 1 to 0.7 μm with increasing [B]/[C] ratios. The application of LII enabled a direct and high-resolution investigation of local distribution of impedance characteristics within the individual grains of BDD. Such an approach resulted in greater understanding of the microstructural control of properties at the grain level. We propose that the obtained surficial variation of impedance is correlated to the areas of high conductance which have been observed at the grain boundaries by using LII. We also postulate that the origin of high conductivity is due to either preferential boron accumulation, the presence of defects, or sp{sup 2} regions in the intragrain regions. The impedance modulus recorded by LII was in full agreement with the bulk impedance measurements. Both variables showed a decreasing trend with increasing [B]/[C] ratios, which is consistent with higher boron incorporation into BDD film.

  14. Compact rat-race ring coupler with meander high-impedance transmission line and port impedance matching

    Directory of Open Access Journals (Sweden)

    Jun He

    2015-08-01

    Full Text Available A novel compact rat-race ring coupler with meander high-impedance transmission line and port impedance matching is presented in this Letter. First, a ring coupler with high port impedance is designed using meander lines. Secondly, an impedance matching section is designed to match the high port impedance to ordinary 50 Ω. The proposed coupler effectively reduces occupied area to 16.8% of conventional one. The design is validated both by simulation and measurement.

  15. Pumping slots: Coupling impedance calculations and estimates

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S.

    1993-08-01

    Coupling impedances of small pumping holes in vacuum-chamber walls have been calculated at low frequencies, i.e., for wavelengths large compared to a typical hole size, in terms of electric and magnetic polarizabilities of the hole. The polarizabilities can be found by solving and electro- or magnetostatic problem and are known analytically for the case of the elliptic shape of the hole in a thin wall. The present paper studies the case of pumping slots. Using results of numerical calculations and analytical approximations of polarizabilities, we give formulae for practically important estimates of slot contribution to low-frequency coupling impedances.

  16. On coupling impedances of pumping holes

    Energy Technology Data Exchange (ETDEWEB)

    Kurennoy, S.

    1993-04-01

    Coupling impedances of a single small hole in vacuum-chamber walls have been calculated at low frequencies. To generalize these results for higher frequencies and/or larger holes one needs to solve coupled integral equations for the effective currents. These equations are solved for two specific hole shapes. The effects of many holes at high frequencies where the impedances are not additive are studied using a perturbation-theory method. The periodic versus random distributions of the pumping holes in the Superconducting Super Collider liner are compared.

  17. Protein Aggregation Measurement through Electrical Impedance Spectroscopy

    Science.gov (United States)

    Affanni, A.; Corazza, A.; Esposito, G.; Fogolari, F.; Polano, M.

    2013-09-01

    The paper presents a novel methodology to measure the fibril formation in protein solutions. We designed a bench consisting of a sensor having interdigitated electrodes, a PDMS hermetic reservoir and an impedance meter automatically driven by calculator. The impedance data are interpolated with a lumped elements model and their change over time can provide information on the aggregation process. Encouraging results have been obtained by testing the methodology on K-casein, a protein of milk, with and without the addition of a drug inhibiting the aggregation. The amount of sample needed to perform this measurement is by far lower than the amount needed by fluorescence analysis.

  18. Electrochemical Impedance Spectroscopy Of Metal Alloys

    Science.gov (United States)

    Macdowell, L. G.; Calle, L. M.

    1993-01-01

    Report describes use of electrochemical impedance spectroscopy (EIS) to investigate resistances of 19 alloys to corrosion under conditions similar to those of corrosive, chloride-laden seaside environment of Space Transportation System launch site. Alloys investigated: Hastelloy C-4, C-22, C-276, and B-2; Inconel(R) 600, 625, and 825; Inco(R) G-3; Monel 400; Zirconium 702; Stainless Steel 304L, 304LN, 316L, 317L, and 904L; 20Cb-3; 7Mo+N; ES2205; and Ferralium 255. Results suggest electrochemical impedance spectroscopy used to predict corrosion performances of metal alloys.

  19. Impedance-matched cavity quantum memory

    CERN Document Server

    Afzelius, Mikael

    2010-01-01

    We consider an atomic frequency comb based quantum memory inside an asymmetric optical cavity. In this configuration it is possible to absorb the input light completely in a system with an effective optical depth of one, provided that the absorption per cavity round trip exactly matches the transmission of the coupling mirror ("impedance matching"). We show that the impedance matching results in a readout efficiency only limited by irreversible atomic dephasing, whose effect can be made very small in systems with large inhomogeneous broadening. Our proposal opens up an attractive route towards quantum memories with close to unit efficiency.

  20. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    and current are derived each period, and the short-circuit impedance is estimated from variations in these components created by load changes in the grid. Due to the noisy and dynamic grid with high harmonic distortion it is necessary to threat the calculated values statistical. This is done recursively...... through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

  1. STATIC AND DYNAMIC LOCATION OF VARIABLE IMPEDANCE DEVICES FOR STABILITY STUDIES

    Directory of Open Access Journals (Sweden)

    N. Magaji

    2013-01-01

    Full Text Available This study used the concept of model controllability and observability in product form called residue factor to find the best location of Thyristor-Controlled based series and shunt devices called variable impedance devices. The success of this controller depends on its best possible location in busbar or line of power system network. The method is based on the relationship between the parameters of variable impedance devices to the vital modes. Linearization of non linear model of Power system and the thyristors based FACTS devices provide mens of computing residue factor and singular value factor. The location of variable impedance or thyristors based controllers have been calculated for the base case only. The usefulness of the these methods of placement considered 16 machines, 68 bus systems.

  2. Thorax mapping for localised lung impedance change using focused impedance measurement (FIM: A pilot study

    Directory of Open Access Journals (Sweden)

    Humayra Ferdous

    2013-12-01

    Full Text Available Focused Impedance Measurement (FIM is a technique where impedance can be measured with the optimum level of localization without much increase in complexity of measuring instrument. The electrodes are applied on the skin surface but the organs inside also contributes to the measurement, as the body is a volume conductor. In a healthy and disease free lung region, the air enters at breathe-in increases the impedance of the lung and impedance reduces during breathe-out. In contrast, for a diseased lung, where part of the lungs is filled with water or some fluid, air will not enter into this zone reducing impedance change between inspiration and expiration. With this idea, the current work had been executed to have general view of localised impedance change throughout thorax using 6-electrode FIM. This generated a matrix mapping from both the front and from the back of the thorax, which  afterwards provided that how impedance change due to ventilation varies from frontal plane to back plane of human bodies.

  3. Locating Impedance Change in Electrical Impedance Tomography Based on Multilevel BP Neural Network

    Institute of Scientific and Technical Information of China (English)

    彭源; 莫玉龙

    2003-01-01

    Electrical impedance tomography (EIT) is a new computer tomography technology, which reconstructs an impedance (resistivity, conductivity) distribution, or change of impedance, by making voltage and current measurements on the object's periphery.Image reconstruction in EIT is an ill-posed, non-linear inverse problem. A method for finding the place of impedance change in EIT is proposed in this paper, in which a multilevel BP neural network (MBPNN) is used to express the non-linear relation between theimpedance change inside the object and the voltage change measured on the surface of the object. Thus, the location of the impedance change can be decided by the measured voltage variation on the surface. The impedance change is then reconstructed using a linear approximate method. MBPNN can decide the impedance change location exactly without long training time. It alleviates some noise effects and can be expanded, ensuring high precision and space resolution of the reconstructed image that are not possible by using the back projection method.

  4. Low-level feedback control for the phase regulation of CLIC Drive Beam Klystrons

    CERN Document Server

    AUTHOR|(SzGeCERN)752526

    2015-01-01

    The requirement of luminosity loss below 1% raises tight tolerances for the phase and power stability of the CLIC drive beam (DB) klystrons and consequently for the high voltage pulse ripple of the modulators. A low-level RF (LLRF) feedback system needs to be developed and combined with the modulator in order to guarantee the phase and amplitude tolerances. To this aim, three feedback control strategies were investigated, i) Proportional Integral (PI) controller, ii) Linear Quadratic Integral Regulator (LQI) and iii) Model Predictive Controller (MPC). The klystron, as well as the incident phase noise were modelled and used for the design and evaluation of the controllers. First simulation results are presented along with future steps and directions.

  5. Electrical Impedance Tomography Technology (EITT) Project

    Science.gov (United States)

    Oliva-Buisson, Yvette J.

    2014-01-01

    Development of a portable, lightweight device providing two-dimensional tomographic imaging of the human body using impedance mapping. This technology can be developed to evaluate health risks and provide appropriate medical care on the ISS, during space travel and on the ground.

  6. Estimating the short-circuit impedance

    DEFF Research Database (Denmark)

    Nielsen, Arne Hejde; Pedersen, Knud Ole Helgesen; Poulsen, Niels Kjølstad

    1997-01-01

    through a RLS-algorithm. The algorithms have been tested and implemented on a PC at a 132 kV substation supplying a rolling mill. Knowing the short-circuit impedance gives the rolling mill an opportunity to adjust the arc furnace operation to keep flicker below a certain level. Therefore, the PC performs...

  7. Measuring mechanical impedance in clayey gravelly soils

    Directory of Open Access Journals (Sweden)

    R. Stolf

    1998-06-01

    Full Text Available Mechanical impedance of clayey and gravelly soils is often needed to interpret experimental results from tillage and other field experiments. Its measurement is difficult with manual and hydraulic penetrometers, which often bend or break in such soils. The purpose of this study was to evaluate the feasibility of a hand-operated "Stolf" impact penetrometer to measure mechanical impedance (soil resistance. The research was conducted in Raleigh, North Carolina, USA (35º 45'N, 78º 42'W, elevation 75 m. Corn was planted on April 19, 1991. Penetrometer measurements were taken on May 10, 1991, in 5 cm intervals to 60 cm at 33 locations on a transect perpendicular to the corn rows in each of four tillage treatments. The data permitted three-dimensional displays showing how mechanical impedance changed with depth and distance along the transect. The impact penetrometer proved to be a useful tool to collect quantitative mechanical impedance data on "hard" clayey and/or gravelly soils which previously were difficult to reliably quantify.

  8. High Impedance Comparator for Monitoring Water Resistivity.

    Science.gov (United States)

    Holewinski, Paul K.

    1984-01-01

    A high-impedance comparator suitable for monitoring the resistivity of a deionized or distilled water line supplying water in the 50 Kohm/cm-2 Mohm/cm range is described. Includes information on required circuits (with diagrams), sensor probe assembly, and calibration techniques. (JN)

  9. Quadratic Boost A-Source Impedance Network

    DEFF Research Database (Denmark)

    Siwakoti, Yam Prasad; Blaabjerg, Frede; Chub, Andrii

    2016-01-01

    A novel quadratic boost type A-source impedance network is proposed in this paper for realizing converters that demand a very high voltage gain. To achieve that, the proposed network uses an auto-transformer, whose obtained gain is quadratically dependent on the duty ratio and is presently not ma...

  10. Electrical Impedance Tomography of Breast Cancer

    Science.gov (United States)

    2005-06-01

    Impedance Scanning; OPAMP , Operational Amplifier; SVD, Singular Value Decomposition; NEX, Number of Excitations; CE-MRI, Contrast Enhanced MRI. 599 600...the Poisson’s built using three LM741 OPAMP circuits to convert the volt- equation with Neumann boundary value conditions. This age from the signal

  11. Impedance-matched drilling telemetry system

    Science.gov (United States)

    Normann, Randy A.; Mansure, Arthur J.

    2008-04-22

    A downhole telemetry system that uses inductance or capacitance as a mode through which signal is communicated across joints between assembled lengths of pipe wherein efficiency of signal propagation through a drill string, for example, over multiple successive pipe segments is enhanced through matching impedances associated with the various telemetry system components.

  12. Surface impedance and the Casimir force

    CERN Document Server

    Bezerra, V B; Romero, C

    2002-01-01

    The impedance boundary condition is used to calculate the Casimir force in configurations of two parallel plates and a shpere (spherical lens) above a plate at both zero and nonzero temperature. The impedance approach allows one to find the Casimir force between the realistic test bodies regardless of the electromagnetic fluctuations inside the media. Although this approach is an approximate one, it has wider areas of application than the Lifshitz theory of the Casimir force. The general formulas of the impedance approach to the theory of the Casimir force are given and the formal substitution is found for connecting it with the Lifshitz formula. The range of micrometer separations between the test bodies which is interesting from the experimental point of view is investigated in detail. It is shown that at zero temperature the results obtained on the basis of the surface impedance method are in agreement with those obtained in framework of the Lifshitz theory within a fraction of a percent. The temperature c...

  13. Online contact impedance identification for robotic systems

    NARCIS (Netherlands)

    Haddadi, Amir; Hashtrudi-Zaad, Keyvan

    2008-01-01

    In this paper, we study the performance of various algorithms for fast online identification of environment impedance during robotic contact tasks. In particular, we evaluate and compare algorithms with regard to their convergence rate, computational complexity and sensitivity to noise for different

  14. Small-signal Loudspeaker Impedance Emulator

    DEFF Research Database (Denmark)

    Knott, Arnold; Iversen, Niels Elkjær

    2014-01-01

    Specifying the performance of audio ampliers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by the mechanical resonance between the mass of the diaphragm and the compliance of its' suspension which vary fr...

  15. Wave impedance retrieving via Bloch modes analysis

    DEFF Research Database (Denmark)

    Andryieuski, Andrei; Ha, S.; Sukhorukov, A.

    2011-01-01

    of the Bloch mode, respectively. Case studies prove that our ap-proach can determine material and wave effective parameters of lossy and lossless metamaterials. In some examples when the passivity is violated we made further analysis and showed that this is due to the failure of concept of impedance retrieving...

  16. Impedance and collective effects in the KEKB

    Energy Technology Data Exchange (ETDEWEB)

    Chin, Yongho [National Lab. for High Energy Physics, Tsukuba, Ibaraki (Japan); Oide, Katsunobu

    1996-08-01

    This paper focuses on beam instabilities due to single-beam collective effects, impedances from various beamline elements, ion trapping, photo-electrons, and other issues in the KEKB. We will also discuss the power deposition generated by a beam in the form of the Higher-Order-Mode (HOM) losses by interacting with its surroundings. (author)

  17. Perioperative bioelectrical impedence analysis in neurosurgery.

    Science.gov (United States)

    El-Dawlatly, Abdelazeem A

    2005-10-01

    The use of bioelectrical impedence (BI) measurement to assess body composition has recently attracted the attention of anesthesiologists. Analysis of BI provides a non-invasive method to quantify fluid distribution in different body compartments. This study was designed to assess whether BI analysis reflects fluid depletion in neurosurgical patients with moderate blood loss. Six adult male patients scheduled for elective craniotomy under general anesthesia were studied. Exclusion criteria included patients with cardio-respiratory disease. BI analysis was performed at three stages, A, day before operation, B, during surgery and C, on the first postoperative day. Total body resistivity was measured by BI analysis with a four-terminal portable impedence analyzer. At each frequency, impedence was calculated as resistance (Rx)2 + reactance (Rc)2. The mean values of total body water (TBW) at stages A, B and C were 39.8 L (range: 33.1-46.7 L), 43.2 L (range: 33.1-66.2 L) and 36.8 L (range: 22.4-36.3 L) respectively with significant differences (P<0.05). The impedence at the three frequencies during stages A, B and C showed significant differences (P<0.05). In conclusion, we have found that in male neurosurgical patients multiple frequency BI measurements has reflected fluid balance perioperatively. Whether this observation remains true for other surgical procedures with massive blood loss, yet to be further investigated.

  18. Microwave transmission-line impedance data

    CERN Document Server

    Gunston, M A R

    1996-01-01

    A compendium of data for computing the characteristic impedance of transmission lines based on physical dimensions. Covers both conventional structures and unusual geometries, including coaxial, eccentric and elliptic coaxial, twin-wire, wire-above-ground, microstrip and derivatives, stripline, slabline and trough line. Also details numerous configurations of coupled lines.

  19. Impedance matching between ventricle and load.

    Science.gov (United States)

    Piene, H

    1984-01-01

    Impedance matching in the cardiovascular system is discussed in light of two models of ventricle and load: a Thevenin equivalent consisting of a hydromotive pressure source and an internal, source resistance and compliance in parallel; and a time-varying compliance filled from a constant pressure source and ejecting into a load of three components, a central resistor, a compliance, and a peripheral resistance. According to the Thevenin analog, the energy source and the load are matched when the load resistance is T/t times the internal source resistance (T is total cycle length, t is systolic time interval). Both from this model and from the variable compliance model it appears that optimum matching between source and load depends on the compliance of the Windkessel, as low compliance shifts the matching load resistance to a low value. Animal experiments (isolated cat hearts) indicated that both left and right ventricles at normal loads work close to their maxima of output hydraulic power, and, according to experiments in the right ventricle, maximum power output is related to load resistance and compliance as predicted by the above models. From an experimentally determined relationship among instantaneous ventricular pressure and volume (right ventricle of isolated cat hearts), an optimum load impedance was calculated on the basis of the assumption that the ratio between stroke work and static, potential energy developed in the ventricular cavity is maximum. The optimum load impedance found by this procedure closely resembles the normal input impedance of the cat lung vessel bed.

  20. Loudspeaker impedance emulator for multi resonant systems

    DEFF Research Database (Denmark)

    Iversen, Niels Elkjær; Knott, Arnold

    2015-01-01

    Specifying the performance of audio amplifiers is typically done by playing sine waves into a pure ohmic load. However real loudspeaker impedances are not purely ohmic but characterised by its electrical, mechanical and acoustical properties. Therefore a loudspeaker emulator capable of adjusting...

  1. Cartesian Impedance Control for Dexterous Robot Hand Based on Dynamic Compensation of Link Torque Sensor%基于连杆力矩传感器动态补偿的机器人灵巧手笛卡儿阻抗控制

    Institute of Scientific and Technical Information of China (English)

    张元飞; 刘伊威; 金明河; 刘宏

    2012-01-01

    为了对连杆空间力矩传感器进行动态补偿,提出了适用于求取串联机器人任意连杆中任意一点处所受的内力和内力矩的算法.该算法采用连杆假想截断原理利用牛顿-欧拉方程推导而出.推导过程综合考虑了串联机器人是否处于静态以及末端是否受外力作用的情况,以及串联机器人的关节是否是回转关节的情况.然后利用该算法计算动态补偿值,构建了基于连杆力矩传感器动态补偿的笛卡儿阻抗控制器.最后在HIT/DLR Hand Ⅱ五指灵巧手上进行了实验验证.实验结果一方面验证了该算法的有效性,另一方面也验证了本文所构建的笛卡儿阻抗控制器的有效性.%In order to achieve dynamic compensation of torque sensor in link space, an effective algorithm for calculating the internal force and torque at any point in any link of a serial robot is proposed. This algorithm is derived by Newton-Euler equations using a hypothetical truncation principle of the link. In the deriving process, some situations are taken into account, such as whether the serial robot is static, whether an external force is exerted on its end, and whether each joint of the serial robot is a rotary joint. Then a Cartesian impedance control scheme based on the dynamic compensation of link torque sensor is developed, in which the dynamic compensative values are calculated by the algorithm. Finally, the algorithm and the Cartesian impedance control scheme are verified on five-finger dexterous hand of HIT/DLR Hand II. The experimental results demonstrate the validity of the algorithm and the Cartesian impedance control scheme.

  2. Monitoring impedance changes associated with motility and mitosis of a single cell.

    Science.gov (United States)

    Ghenim, Lamya; Kaji, Hirokazu; Hoshino, Yu; Ishibashi, Takeshi; Haguet, Vincent; Gidrol, Xavier; Nishizawa, Matsuhiko

    2010-10-07

    We present a device enabling impedance measurements that probe the motility and mitosis of a single adherent cell in a controlled way. The micrometre-sized electrodes are designed for adhesion of an isolated cell and enhanced sensitivity to cell motion. The electrode surface is switched electro-chemically to favour cell adhesion, and single cells are attracted to the electrode using positive dielectrophoresis. Periods of linear variation in impedance with time correspond to the motility of a single cell adherent to the surface estimated at 0.6 μm h(-1). In the course of our study we observed the impedance changes associated with mitosis of a single cell. Electrical measurements, carried out concomitantly with optical observations, revealed three phases, prophase, metaphase and anaphase in the time variation of the impedance during cell division. Maximal impedance was observed at metaphase with a 20% increase of the impedance. We argue that at mitosis, the changes detected were due to the charge density distribution at the cell surface. Our data demonstrate subtle electrical changes associated with cell motility and for the first time with division at the single-cell level. We speculate that this could open up new avenues for characterizing healthy and pathological cells.

  3. Impedance Eduction in Large Ducts Containing Higher-Order Modes and Grazing Flow

    Science.gov (United States)

    Watson, Willie R.; Jones, Michael G.

    2017-01-01

    Impedance eduction test data are acquired in ducts with small and large cross-sectional areas at the NASA Langley Research Center. An improved data acquisition system in the large duct has resulted in increased control of the acoustic energy in source modes and more accurate resolution of higher-order duct modes compared to previous tests. Two impedance eduction methods that take advantage of the improved data acquisition to educe the liner impedance in grazing flow are presented. One method measures the axial propagation constant of a dominant mode in the liner test section (by implementing the Kumarsean and Tufts algorithm) and educes the impedance from an exact analytical expression. The second method solves numerically the convected Helmholtz equation and minimizes an objective function to obtain the liner impedance. The two methods are tested first on data synthesized from an exact mode solution and then on measured data. Results show that when the methods are applied to data acquired in the larger duct with a dominant higher-order mode, the same impedance spectra are educed as that obtained in the small duct where only the plane wave mode propagates. This result holds for each higher-order mode in the large duct provided that the higher-order mode is sufficiently attenuated by the liner.

  4. Development of an impedance-based wireless sensor node for structural health monitoring

    Science.gov (United States)

    Mascarenas, David L.; Todd, Michael D.; Park, Gyuhae; Farrar, Charles R.

    2007-12-01

    This paper presents the development and application of a miniaturized impedance sensor node for structural health monitoring (SHM). A large amount of research has been focused on utilizing the impedance method for structural health monitoring. The vast majority of this research, however, has required the use of expensive and bulky impedance analyzers that are not suitable for field deployment. In this study, we developed a wireless impedance sensor node equipped with a low-cost integrated circuit chip that can measure and record the electrical impedance of a piezoelectric transducer, a microcontroller that performs local computing and a wireless telemetry module that transmits the structural information to a base station. The performance of this miniaturized and portable device has been compared to results obtained with a conventional impedance analyzer and its effectiveness has been demonstrated in an experiment to detect loss of preload in a bolted joint. Furthermore, for the first time, we also consider the problem of wireless powering of such SHM sensor nodes, where we use radio-frequency wireless energy transmission to deliver electrical energy to power the sensor node. In this way, the sensor node does not have to rely on an on-board power source, and the required energy can be wirelessly delivered as needed by human or a remotely controlled robotic device.

  5. Cardiorespiratory Mechanical Simulator for In Vitro Testing of Impedance Minute Ventilation Sensors in Cardiac Pacemakers.

    Science.gov (United States)

    Marcelli, Emanuela; Cercenelli, Laura

    2016-01-01

    We developed a cardiorespiratory mechanical simulator (CRMS), a system able to reproduce both the cardiac and respiratory movements, intended to be used for in vitro testing of impedance minute ventilation (iMV) sensors in cardiac pacemakers. The simulator consists of two actuators anchored to a human thorax model and a software interface to control the actuators and to acquire/process impedance signals. The actuators can be driven separately or simultaneously to reproduce the cardiac longitudinal shortening at a programmable heart rate and the diaphragm displacement at a programmable respiratory rate (RR). A standard bipolar pacing lead moving with the actuators and a pacemaker case fixed to the thorax model have been used to measure impedance (Z) variations during the simulated cardiorespiratory movements. The software is able to discriminate the low-frequency component because of respiration (Z(R)) from the high-frequency ripple because of cardiac effect (Z(C)). Impedance minute ventilation is continuously calculated from Z(R) and RR. From preliminary tests, the CRMS proved to be a reliable simulator for in vitro evaluation of iMV sensors. Respiration impedance recordings collected during cardiorespiratory movements reproduced by the CRMS were comparable in morphology and amplitude with in vivo assessments of transthoracic impedance variations.

  6. Characterisation and modelling of a high temperature PEM fuel cell stack using electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jespersen, J.L. [Danish Technological Institute, Kongsvang Alle 29, DK-8000 Arhus C (Denmark); Schaltz, E.; Kaer, S.K. [Department of Energy Technology, Aalborg University, Pontoppidanstraede 101, DK-9220 Aalborg East (Denmark); Andreasen, S.J.

    2009-08-15

    In designing and controlling fuel cell systems, it is advantageous to have models which predict fuel cell behaviour in steady-state as well as in dynamic operation. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterising and developing an impedance model for a high temperature PEM (HT-PEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell is a Nyquist plot, which shows the imaginary and real parts of the impedance of the measured system. The full stack impedance depends on the impedance of each of the single cells of the stack. Equivalent circuit models for each single cell can be used to predict the stack impedance at different temperature profiles of the stack. The information available in such models can be used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  7. Skin Impedance Measurements for Acupuncture Research: Development of a Continuous Recording System

    Directory of Open Access Journals (Sweden)

    Agatha P. Colbert

    2008-01-01

    Full Text Available Skin impedance at acupuncture points (APs has been used as a diagnostic/therapeutic aid for more than 50 years. Currently, researchers are evaluating the electrophysiologic properties of APs as a possible means of understanding acupuncture's mechanism. To comprehensively assess the diagnostic, therapeutic and mechanistic implications of acupuncture point skin impedance, a device capable of reliably recording impedances from 100 kΩ to 50 MΩ at multiple APs over extended time periods is needed. This article describes design considerations, development and testing of a single channel skin impedance system (hardware, control software and customized electrodes. The system was tested for accuracy against known resistors and capacitors. Two electrodes (the AMI and the ORI were compared for reliability of recording over 30 min. Two APs (LU 9 and PC 6 and a nearby non-AP site were measured simultaneously in four individuals for 60 min. Our measurement system performed accurately (within 5% against known resistors (580 kΩ–10 MΩ and capacitors (10 nF–150 nF. Both the AMI electrode and the modified ORI electrode recorded skin impedance reliably on the volar surface of the forearm (r = 0.87 and r = 0.79, respectively. In four of four volunteers tested, skin impedance at LU 9 was less than at the nearby non-AP site. In three of four volunteers skin impedance was less at PC 6 than at the nearby non-AP site. We conclude that our system is a suitable device upon which we can develop a fully automated multi-channel device capable of recording skin impedance at multiple APs simultaneously over 24 h.

  8. Skin Impedance Measurements for Acupuncture Research: Development of a Continuous Recording System

    Science.gov (United States)

    Yun, Jinkook; Larsen, Adrian; Edinger, Tracy; Gregory, William L.; Thong, Tran

    2008-01-01

    Skin impedance at acupuncture points (APs) has been used as a diagnostic/therapeutic aid for more than 50 years. Currently, researchers are evaluating the electrophysiologic properties of APs as a possible means of understanding acupuncture's mechanism. To comprehensively assess the diagnostic, therapeutic and mechanistic implications of acupuncture point skin impedance, a device capable of reliably recording impedances from 100 kΩ to 50 MΩ at multiple APs over extended time periods is needed. This article describes design considerations, development and testing of a single channel skin impedance system (hardware, control software and customized electrodes). The system was tested for accuracy against known resistors and capacitors. Two electrodes (the AMI and the ORI) were compared for reliability of recording over 30 min. Two APs (LU 9 and PC 6) and a nearby non-AP site were measured simultaneously in four individuals for 60 min. Our measurement system performed accurately (within 5%) against known resistors (580 kΩ–10 MΩ) and capacitors (10 nF–150 nF). Both the AMI electrode and the modified ORI electrode recorded skin impedance reliably on the volar surface of the forearm (r = 0.87 and r = 0.79, respectively). In four of four volunteers tested, skin impedance at LU 9 was less than at the nearby non-AP site. In three of four volunteers skin impedance was less at PC 6 than at the nearby non-AP site. We conclude that our system is a suitable device upon which we can develop a fully automated multi-channel device capable of recording skin impedance at multiple APs simultaneously over 24 h. PMID:18955218

  9. On the impedance of galvanic cells—XVI The impedance of the dropping mercury electrode in aqueous 1 M KCl with K+ discharge

    NARCIS (Netherlands)

    Sluyters-Rehbach, M.; Sluyters, J.H.

    1966-01-01

    The discharge of K+ ions at the dropping mercury electrode (dme) in 1 M KCl solution at 25°C has been studied by means of analysis of the electrode impedance at different frequencies, using the complex plane method. It is shown that the electrode reaction is almost entirely diffusion-controlled, but

  10. Beam measurements of the LHC impedance and validation of the impedance model

    CERN Document Server

    Esteban Müller, J F; Bohl, T; Mounet, N; Shaposhnikova, E; Timko, H

    2014-01-01

    Different measurements of the longitudinal impedance of the LHC done with single bunches with various intensities and longitudinal emittances during measurement sessions in 2011-2012 are compared with particle simulations based on the existing LHC impedance model. The very low reactive impedance of the LHC, with Im Z=n = 0.08, is not easy to measure. The most sensitive observation is the loss of Landau damping, which shows at which energy bunches become unstable depending on their parameters. In addition, the synchrotron frequency shift due to the reactive impedance was estimated following two methods. Firstly, it was obtained from the peak-detected Schottky spectrum. Secondly, a sine modulation in the RF phase was applied to the bunches of different intensities and the modulation frequency was scanned. In both cases, the synchrotron frequency shift was of the order of the measurement precision.

  11. Dynamic electrochemical impedance spectroscopy reconstructed from continuous impedance measurement of single frequency during charging/discharging

    Science.gov (United States)

    Huang, Jun; Li, Zhe; Zhang, Jianbo

    2015-01-01

    In this study, a novel implementation of dynamic electrochemical impedance spectroscopy (DEIS) is proposed. The method first measures the impedance continuously at a single frequency during one charging/discharging cycle, then repeats the measurement at a number of other selected frequencies. The impedance spectrum at a specific SOC is obtained by interpolating and collecting the impedance at all of the selected frequencies. The charge transfer resistance, Rct, from the DEIS is smaller than that from the steady EIS in a wide state-of-charge (SOC) range from 0.4 to 1.0, the Rct during charging is generally smaller than that during discharging for the battery chemistry used in this study.

  12. Concentric artificial impedance surface for directional sound beamforming

    Science.gov (United States)

    Song, Kyungjun; Anzan-Uz-Zaman, Md.; Kwak, Jun-Hyuk; Jung, Joo-Yun; Kim, Jedo; Hur, Shin

    2017-03-01

    Utilizing acoustic metasurfaces consisting of subwavelength resonant textures, we design an artificial impedance surface by creating a new boundary condition. We demonstrate a circular artificial impedance surface with surface impedance modulation for directional sound beamforming in three-dimensional space. This artificial impedance surface is implemented by revolving two-dimensional Helmholtz resonators with varying internal coiled path. Physically, the textured surface has inductive surface impedance on its inner circular patterns and capacitive surface impedance on its outer circular patterns. Directional receive beamforming can be achieved using an omnidirectional microphone located at the focal point formed by the gradient-impeding surface. In addition, the uniaxial surface impedance patterning inside the circular aperture can be used for steering the direction of the main lobe of the radiation pattern.

  13. Scattering by a groove in an impedance plane

    Science.gov (United States)

    Bindiganavale, Sunil; Volakis, John L.

    1993-09-01

    An analysis of two-dimensional scattering from a narrow groove in an impedance plane is presented. The groove is represented by a impedance surface and the problem reduces to that of scattering from an impedance strip in an otherwise uniform impedance plane. On the basis of this model, appropriate integral equations are constructed using a form of the impedance plane Green's functions involving rapidly convergent integrals. The integral equations are solved by introducing a single basis representation of the equivalent current on the narrow impedance insert. Both transverse electric (TE) and transverse magnetic (TM) polarizations are treated. The resulting solution is validated by comparison with results from the standard boundary integral method (BIM) and a high frequency solution. It is found that the presented solution for narrow impedance inserts can be used in conjunction with the high frequency solution for the characterization of impedance inserts of any given width.

  14. Electrochemical Impedance of Ethanol Oxidation in Alkaline Media

    Institute of Scientific and Technical Information of China (English)

    DANAEE Iman; JAFARIAN Majid; GOBAL Fereydoon; SHARAFI Mahboobeh; MAHJANI Mohammad-ghasem

    2012-01-01

    Nickel modified NiOOH electrodes were used for the electrocatalytic oxidation of ethanol in alkaline solutions.The electro-oxidation of ethanol in a 1 mol/L NaOH solution at different concentrations of ethanol was studied by ac impedance spectroscopy.Electrooxidation of ethanol on Ni shows negative resistance on impedance plots.The impedance shows different patterns at different applied anodic potential.The influence of the electrode potential on impedance was studied and a quantitative explanation for the impedance of ethanol oxidation was given by means of a proposed mathematical model.At potentials higher than 0.52 V(vs.Ag/AgCl),a pseudoinductive behavior was observed,but at those higher than 0.57 V,impedance patterns were reversed to the second and third quadrants.The conditions required for the reversing of impedance pattern were delineated with the impedance model.

  15. Impeding movement of the poultry red mite, Dermanyssus gallinae.

    Science.gov (United States)

    Pritchard, James; Küster, Tatiana; George, David; Sparagano, Olivier; Tomley, Fiona

    2016-07-30

    The poultry red mite, Dermanyssus gallinae, is an economically important hematophagous parasite of commercial egg laying hens, also affecting domesticated birds and companion animals. Conventional control of D. gallinae through acaricidal spraying is often ineffective, creating an urgent need to identify alternative management strategies for commercial and domestic infestations. Whilst integrated pest management is being considered for D. gallinae, the potential of impeding mite 'migration' routes, to either prevent initial infestation or manage established populations, has not been researched. Here we demonstrate that barriers of insecticidal glue, double sided sticky tape and thyme oil can contain D. gallinae within a specified area of a petri dish (78-88% of total mite population) and this level of containment was significantly greater than for negative controls (p values <0.05). Further studies in poultry houses are recommended to investigate the efficacy of these barriers in real world application and identity potential for barriers as a strategy for mite control.

  16. TCSC impedance regulator applied to the second benchmark model

    Energy Technology Data Exchange (ETDEWEB)

    Hamel, J.P.; Dessaint, L.A. [Ecole de Technologie Superieure, Montreal, PQ (Canada). Dept. of Electrical Engineering; Champagne, R. [Ecole de Technologie Superieure, Montreal, PQ (Canada). Dept. of Software and IT Engineering; Pare, D. [Institut de Recherche d' Hydro-Quebec, Varennes, PQ (Canada)

    2008-07-01

    Due to the combination of electrical demand growth and the high cost of building new power transmission lines, series compensation is increasingly used in power systems all around the world. Series compensation has been proposed as a new way to transfer more power on existing lines. By adding series compensation to an existing line (a relatively small change), the power transfer can be increased significantly. One of the means used for line compensation is the addition of capacitive elements in series with the line. This paper presented a thyristor-controlled series capacitor (TCSC) model that used impedance as reference, had individual controls for each phase, included a linearization module and considered only the fundamental frequency for impedance computations, without using any filter. The model's dynamic behavior was validated by applying it to the second benchmark model for subsynchronous resonance (SSR). Simulation results from the proposed model, obtained using EMTP-RV and SimPowerSystems were demonstrated. It was concluded that SSR was mitigated by the proposed approach. 19 refs., 19 figs.

  17. Current injection electrodes for electrical impedance tomography.

    Science.gov (United States)

    Armstrong, S; Jennings, D

    2004-08-01

    Current conveyors have been identified as a possible component within the current injection electrodes of an electrical impedance tomography system, where accurate current generation or precise measurement of the current injected is required. Several circuit configurations have been investigated through simulation to determine the most suitable to meet the specifications of the EIT system. A bipolar (floating source) circuit configuration employing the use of current conveyors has been designed, which achieves greater than 12 mA output current without saturation, over an accepted body impedance range. Simulations were performed over frequencies in excess of 1 MHz, and the output phase shift was less than 0.15 degrees up to 250 kHz, and 0.6 degrees up to 1 MHz.

  18. FEM electrode refinement for electrical impedance tomography.

    Science.gov (United States)

    Grychtol, Bartlomiej; Adler, Andy

    2013-01-01

    Electrical Impedance Tomography (EIT) reconstructs images of electrical tissue properties within a body from electrical transfer impedance measurements at surface electrodes. Reconstruction of EIT images requires the solution of an inverse problem in soft field tomography, where a sensitivity matrix, J, of the relationship between internal changes and measurements is calculated, and then a pseudo-inverse of J is used to update the image estimate. It is therefore clear that a precise calculation of J is required for solution accuracy. Since it is generally not possible to use analytic solutions, the finite element method (FEM) is typically used. It has generally been recommended in the EIT literature that FEMs be refined near electrodes, since the electric field and sensitivity is largest there. In this paper we analyze the accuracy requirement for FEM refinement near electrodes in EIT and describe a technique to refine arbitrary FEMs.

  19. Microwave impedance imaging on semiconductor memory devices

    Science.gov (United States)

    Kundhikanjana, Worasom; Lai, Keji; Yang, Yongliang; Kelly, Michael; Shen, Zhi-Xun

    2011-03-01

    Microwave impedance microscopy (MIM) maps out the real and imaginary components of the tip-sample impedance, from which the local conductivity and dielectric constant distribution can be derived. The stray field contribution is minimized in our shielded cantilever design, enabling quantitative analysis of nano-materials and device structures. We demonstrate here that the MIM can spatially resolve the conductivity variation in a dynamic random access memory (DRAM) sample. With DC or low-frequency AC bias applied to the tip, contrast between n-doped and p-doped regions in the dC/dV images is observed, and p-n junctions are highlighted in the dR/dV images. The results can be directly compared with data taken by scanning capacitance microscope (SCM), which uses unshielded cantilevers and resonant electronics, and the MIM reveals more information of the local dopant concentration than SCM.

  20. The electrochemical impedance of metal hydride electrodes

    DEFF Research Database (Denmark)

    Valøen, Lars Ole; Lasia, Andrzej; Jensen, Jens Oluf

    2002-01-01

    The electrochemical impedance responses for different laboratory type metal hydride electrodes were successfully modeled and fitted to experimental data for AB5 type hydrogen storage alloys as well as one MgNi type electrode. The models fitted the experimental data remarkably well. Several AC......, explaining the experimental impedances in a wide frequency range for electrodes of hydride forming materials mixed with copper powder, were obtained. Both charge transfer and spherical diffusion of hydrogen in the particles are important sub processes that govern the total rate of the electrochemical...... hydrogen absorption/desorption reaction. To approximate the experimental data, equations describing the current distribution in porous electrodes were needed. Indications of one or more parallel reduction/oxidation processes competing with the electrochemical hydrogen absorption/desorption reaction were...

  1. Estimating the Transverse Impedance in the Fermilab Recycler

    Energy Technology Data Exchange (ETDEWEB)

    Ainsworth, Robert [Fermilab; Adamson, Philip [Fermilab; Burov, Alexey [Fermilab; Kourbanis, Ioanis [Fermilab; Yang, Ming-Jen [Fermilab

    2016-06-01

    Impedance could represent a limitation of running high intensity bunches in the Fermilab recycler. With high intensity upgrades foreseen, it is important to quantify the impedance. To do this, studies have been performed measuring the tune shift as a function of bunch intensity allowing the transverse impedance to be derived.

  2. PHEMT Distributed Power Amplifier Adopting Broadband Impedance Transformer

    DEFF Research Database (Denmark)

    Narendra, K.; Limiti, E.; Paoloni, C.

    2013-01-01

    A non-uniform drain line distributed power amplifier (DPA) employing a broadband impedance transformer is presented. The DPA is based on GaAs PHEMT technology. The impedance transformer employs asymmetric coupled lines and transforms a low output impedance of the amplifier to a standard 50 Ω...

  3. Analog Video Line Driver with Adaptive Impedance Matching

    NARCIS (Netherlands)

    Nauta, Bram; Dijkstra, Marcel B.

    1998-01-01

    A new principle for an adaptive line driver is presented. This type of line driver can adapt its output impedance automatically to the applied load. This results in automatically corrected output impedance for different cables with terminations. Also, the line-driver output impedance becomes insensi

  4. Effect of rib-cage structure on acoustic chest impedance

    DEFF Research Database (Denmark)

    Zimmermann, Niels Henrik; Møller, Henrik; Hansen, John

    2011-01-01

    even weak sounds originating from e.g. the heart. The acoustic impedance is influenced by the structure of the ribcage; hence the acoustic impedance will change depending on if the coupler has been placed on a top of a rib or between the ribs (the intercostal). The impedance of the chest is measured...

  5. EPICS based low-level radio frequency control system in LIPAc

    Energy Technology Data Exchange (ETDEWEB)

    Calvo, Julio, E-mail: julio.calvo@ciemat.es [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Ciemat (Spain); Rivers, Mark L. [Department of Geophysical Sciences and Center for Advanced Radiation Sources, The University of Chicago (United States); Patricio, Miguel A. [Departamento de Informatica, Universidad Carlos III de Madrid (Spain); Ibarra, Angel [Centro de Investigaciones Energeticas Medioambientales y Tecnologicas, Ciemat (Spain)

    2012-11-15

    Highlights: Black-Right-Pointing-Pointer The system proposed can control amplitude and phase of each cavity. Black-Right-Pointing-Pointer Rapid diagnostics are refreshed in milliseconds. Black-Right-Pointing-Pointer Increasing control parameters will not increase consumed time neither complexity. Black-Right-Pointing-Pointer IQ demodulation can be achieved thanks to the transformed values at driver level. - Abstract: The IFMIF-EVEDA (International Fusion Materials Irradiation Facility - Engineering Validation and Engineering Design Activity) linear accelerator, known as Linear IFMIF Prototype Accelerator (LIPAc), will be a 9 MeV, 125 mA continuous wave (CW) deuteron accelerator prototype to validate the technical options of the accelerator design for IFMIF. The primary mission of such facility is to test and verify materials performance when subjected to extensive neutron irradiation of the type encountered in a fusion reactor to prepare for the design, construction, licensing and safe operation of a fusion demonstration reactor (DEMO). The radio frequency (RF) power system of IFMIF-EVEDA consists of 18 RF chains working at 175 MHz with three amplification stages each. The low-level radio frequency (LLRF) controls the amplitude and phase of the signal to be synchronized with the beam and it also controls the resonance frequency of the cavities. The system is based on a commercial compact peripheral component interconnect (cPCI) field programmable gate array (FPGA) board, provided by Lyrtech and controlled by a Windows host PC. For this purpose, it is mandatory to communicate the cPCI FPGA board from EPICS Channel Access [1]. A software architecture on EPICS framework in order to control and monitor the LLRF system is presented.

  6. Comparison of Wired and Wireless Bio-Electrical Impedance Fluid Status Monitoring Devices and Validation to Body Mass and Urine Specific Gravity Changes Following Mild Dehydration

    Science.gov (United States)

    2008-01-18

    status assessment method, ZOE2, is FDA approved for fluid status monitoring. The ZOE2 measures thoracic bio -electrical impedance. A new wireless version...impedance as a valid measure of hydration status in clinical or controlled settings. However, there is speculation as to the utility of bio -electrical...no significant differences were detected between pre- to post-practice for the ZOE2 or ZOEW device. Bio -electrical impedance, as measured by the ZOEW

  7. Summary of impedance issues and beam instabilities

    CERN Document Server

    Zimmermann, Frank

    2016-01-01

    This paper summarizes the session on impedance issues and beam instabilities at the ICFA workshop on future circular electron-positron factories “eeFACT2016” [1] held at the Cockcroft Institute, Daresbury, from 24 to 27 October 2016. This session also covered active beam stabilization by feedback systems. Beam-beam effects and coherent beambeam instabilities were addressed separately and, therefore, are not included here.

  8. Applications of Nonlinear Electrochemical Impedance Spectroscopy (NLEIS)

    KAUST Repository

    Adler, S. B.

    2013-08-31

    This paper reviews the use of nonlinear electrochemical impedance spectroscopy (NLEIS) in the analysis of SOFC electrode reactions. By combining EIS and NLEIS, as well as other independent information about an electrode material, it becomes possible to establish quantitative links between electrochemical kinetics and materials properties, even when systems are unstable with time. After a brief review of the method, this paper summarizes recent results analyzing the effects of Sr segregation in thin-film LSC electrodes. © The Electrochemical Society.

  9. IMPEDANCE SPECTROSCOPY OF POLYCRYSTALLINE TIN DIOXIDE FILMS

    Directory of Open Access Journals (Sweden)

    D. V. Adamchuck

    2016-01-01

    Full Text Available The aim of this work is the analysis of the influence of annealing in an inert atmosphere on the electrical properties and structure of non-stoichiometric tin dioxide films by means of impedance spectroscopy method. Non-stoichiometric tin dioxide films were fabricated by two-step oxidation of metallic tin deposited on the polycrystalline Al2O3 substrates by DC magnetron sputtering. In order to modify the structure and stoichiometric composition, the films were subjected to the high temperature annealing in argon atmosphere in temperature range 300–800 °С. AC-conductivity measurements of the films in the frequency range 20 Hz – 2 MHz were carried out. Variation in the frequency dependencies of the real and imaginary parts of the impedance of tin dioxide films was found to occur as a result of high-temperature annealing. Equivalent circuits for describing the properties of films with various structure and stoichiometric composition were proposed. Possibility of conductivity variation of the polycrystalline tin dioxide films as a result of аnnealing in an inert atmosphere was demonstrated by utilizing impedance spectroscopy. Annealing induces the recrystallization of the films, changing in their stoichiometry as well as increase of the sizes of SnO2 crystallites. Variation of electrical conductivity and structure of tin dioxide films as a result of annealing in inert atmosphere was confirmed by X-ray diffraction analysis. Analysis of the impedance diagrams of tin dioxide films was found to be a powerful tool to study their electrical properties. 

  10. OCM and Impedance Analysis of Polypyrrole

    Science.gov (United States)

    1990-05-01

    0e 4 ’.6. SUPPLEMENTARY NOTATION 178th Meeting of the Electrochemical Society , Seattle, Washington, October 1990 !7 COSA7 CODES -4) SUBJECT TERMS...to: The Electrochemical Society , Inc. Abstract No. 10 South Main Street Pennington, NJ 08534.2696 (to be assigned by te Society) With a copy to the... Electrochemical Society . Inc. QCM and Impedance Analysis of Polypyrrole CoLe-Cole plots for anion -intercalating polypyrrole Mary M. Lien. Hesi-ku Park. and

  11. Electrode models in electrical impedance tomography

    Institute of Scientific and Technical Information of China (English)

    WANG M.

    2005-01-01

    This paper presents different views on electrode modelling, which include electrode electrochemistry models for modelling the effects of electrode-electrolyte interface, electric field electrode models for modelling electrode geometry, and electrode models for modelling the effects of electrode common mode voltage and double layer capacitance. Taking the full electrode models into consideration .in electrical impedance tomography (EIT) will greatly help the optimised approach to a good solution and further understanding of the measurement principle.

  12. Giant Magneto-Impedance and its Applications

    CERN Document Server

    Tannous, C

    2002-01-01

    The status of Giant Magneto-Impedance effect is reviewed in Wires, Ribbons and Multilayered Soft Ferromagnetic Thin Films. After establishing the theoretical framework for the description of the effect, and the constraints any material should have in order to show the effect, experimental work in Wires, Ribbons and Multilayered Thin Films is described. Existing and potential applications of the effect in Electronics and Sensing are highlighted.

  13. Impedance Matched Absorptive Thermal Blocking Filters

    CERN Document Server

    Wollack, E J; Rostem, K; U-Yen, K

    2014-01-01

    We have designed, fabricated and characterized absorptive thermal blocking filters for cryogenic microwave applications. The transmission line filter's input characteristic impedance is designed to match $50\\,\\Omega$ and its response has been validated from 0-to-50\\,GHz. The observed return loss in the 0-to-20\\,GHz design band is greater than $20\\,$dB and shows graceful degradation with frequency. Design considerations and equations are provided that enable this approach to be scaled and modified for use in other applications.

  14. Bioelectrical impedance analysis of bovine milk fat

    Science.gov (United States)

    Veiga, E. A.; Bertemes-Filho, P.

    2012-12-01

    Three samples of 250ml at home temperature of 20°C were obtained from whole, low fat and fat free bovine UHT milk. They were analysed by measuring both impedance spectra and dc conductivity in order to establish the relationship between samples related to fat content. An impedance measuring system was developed, which is based on digital oscilloscope, a current source and a FPGA. Data was measured by the oscilloscope in the frequency 1 kHz to 100 kHz. It was showed that there is approximately 7.9% difference in the conductivity between whole and low fat milk whereas 15.9% between low fat and free fat one. The change of fatness in the milk can be significantly sensed by both impedance spectra measurements and dc conductivity. This result might be useful for detecting fat content of milk in a very simple way and also may help the development of sensors for measuring milk quality, as for example the detection of mastitis.

  15. Application of impedance spectroscopy to SOFC research

    Energy Technology Data Exchange (ETDEWEB)

    Hsieh, G.; Mason, T.O. [Northwestern Univ., Evanston, IL (United States); Pederson, L.R. [Pacific Northwest National Lab., Richland, WA (United States)

    1996-12-31

    With the resurgence of interest in solid oxide fuel cells and other solid state electrochemical devices, techniques originally developed for characterizing aqueous systems are being adapted and applied to solid state systems. One of these techniques, three-electrode impedance spectroscopy, is particularly powerful as it allows characterization of subcomponent and interfacial properties. Obtaining accurate impedance spectra, however, is difficult as reference electrode impedance is usually non-negligible and solid electrolytes typically have much lower conductance than aqueous solutions. Faidi et al and Chechirlian et al have both identified problems associated with low conductivity media. Other sources of error are still being uncovered. Ford et al identified resistive contacts with large time constants as a possibility, while Me et al showed that the small contact capacitance of the reference electrode was at fault. Still others show that instrument limitations play a role. Using the voltage divider concept, a simplified model that demonstrates the interplay of these various factors, predicts the form of possible distortions, and offers means to minimize errors is presented.

  16. Stability of Grid-Connected PV Inverters with Large Grid Impedance Variation

    DEFF Research Database (Denmark)

    Liserre, Marco; Teodorescu, Remus; Blaabjerg, Frede

    2004-01-01

    Photovoltaic (PV) inverters used in dispersed power generation of houses in the range of 1-5 kW are currently available from several manufactures. However, large grid impedance variation is challenging the control and the grid filter design in terms of stability. In fact the PV systems are well...... suited for loads connected in a great distance to the transformer (long wires) and the situation becomes even more difficult in low-developed remote areas characterized by low power transformers and long distribution wires with high grid impedance. Hence a theoretical analysis is needed because the grid...... the design of resonant controllers adopted to mitigate the effect of the grid harmonic distortion on the grid current. In the high frequency range the grid impedance influence the frequency characteristic of the filter and the design of passive or active damping (to ensure stability) becomes more difficult...

  17. Design and validation of a platform robot for determination of ankle impedance during ambulation.

    Science.gov (United States)

    Rouse, Elliott J; Hargrove, Levi J; Peshkin, Michael A; Kuiken, Todd A

    2011-01-01

    In order to provide natural, biomimetic control to recently developed powered ankle prostheses, we must characterize the impedance of the ankle during ambulation tasks. To this end, a platform robot was developed that can apply an angular perturbation to the ankle during ambulation and simultaneously acquire ground reaction force data. In this study, we detail the design of the platform robot and characterize the impedance of the ankle during quiet standing. Subjects were perturbed by a 3° dorsiflexive ramp perturbation with a length of 150 ms. The impedance was defined parametrically, using a second order model to map joint angle to the torque response. The torque was determined using the inverted pendulum assumption, and impedance was identified by the least squares best estimate, yielding an average damping coefficient of 0.03 ± 0.01 Nms/° and an average stiffness coefficient of 3.1 ± 1.2 Nm/°. The estimates obtained by the proposed platform robot compare favorably to those published in the literature. Future work will investigate the impedance of the ankle during ambulation for powered prosthesis controller development.

  18. A Portable Impedance Immunosensing System for Rapid Detection of Salmonella Typhimurium.

    Science.gov (United States)

    Wen, Tao; Wang, Ronghui; Sotero, America; Li, Yanbin

    2017-08-28

    SalmonellaTyphimurium is one of the most dangerous foodborne pathogens and poses a significant threat to human health. The objective of this study was to develop a portable impedance immunosensing system for rapid and sensitive detection of S. Typhimurium in poultry. The developed portable impedance immunosensing system consisted of a gold interdigitated array microelectrode (IDAM), a signal acquisitive interface and a laptop computer with LabVIEW software. The IDAM was first functionalized with 16-Mercaptohexadecanoic acid, and streptavidin was immobilized onto the electrode surface through covalent bonding. Then, biotin-labelled S. Typhimurium-antibody was immobilized onto the IDAM surface. Samples were dropped on the surface of the IDAM and the S. Typhimurium cells in the samples were captured by the antibody on the IDAM. This resulted in impedance changes that were measured and displayed with the LabVIEW software. An equivalent circuit of the immunosensor demonstrated that the largest change in impedance was due to the electron-transfer resistance. The equivalent circuit showed an increase of 35% for the electron-transfer resistance value compared to the negative control. The calibration result indicated that the portable impedance immunosensing system could be used to measure the standard impedance elements, and it had a maximum error of measurement of approximately 13%. For pure culture detection, the system had a linear relationship between the impedance change and the logarithmic value of S. Typhimurium cells ranging from 76 to 7.6 × 10⁶ CFU (colony-forming unit) (50 μL)(-1). The immunosensor also had a correlation coefficient of 0.98, and a high specificity for detection of S. Typhimurium cells with a limit of detection (LOD) of 10² CFU (50 μL)(-1). The detection time from the moment a sample was introduced to the display of the results was 1 h. To conclude, the portable impedance immunosensing system for detection of S. Typhimurium achieved an LOD

  19. A Portable Impedance Immunosensing System for Rapid Detection of Salmonella Typhimurium

    Directory of Open Access Journals (Sweden)

    Tao Wen

    2017-08-01

    Full Text Available Salmonella Typhimurium is one of the most dangerous foodborne pathogens and poses a significant threat to human health. The objective of this study was to develop a portable impedance immunosensing system for rapid and sensitive detection of S. Typhimurium in poultry. The developed portable impedance immunosensing system consisted of a gold interdigitated array microelectrode (IDAM, a signal acquisitive interface and a laptop computer with LabVIEW software. The IDAM was first functionalized with 16-Mercaptohexadecanoic acid, and streptavidin was immobilized onto the electrode surface through covalent bonding. Then, biotin-labelled S. Typhimurium-antibody was immobilized onto the IDAM surface. Samples were dropped on the surface of the IDAM and the S. Typhimurium cells in the samples were captured by the antibody on the IDAM. This resulted in impedance changes that were measured and displayed with the LabVIEW software. An equivalent circuit of the immunosensor demonstrated that the largest change in impedance was due to the electron-transfer resistance. The equivalent circuit showed an increase of 35% for the electron-transfer resistance value compared to the negative control. The calibration result indicated that the portable impedance immunosensing system could be used to measure the standard impedance elements, and it had a maximum error of measurement of approximately 13%. For pure culture detection, the system had a linear relationship between the impedance change and the logarithmic value of S. Typhimurium cells ranging from 76 to 7.6 × 106 CFU (colony-forming unit (50 μL−1. The immunosensor also had a correlation coefficient of 0.98, and a high specificity for detection of S. Typhimurium cells with a limit of detection (LOD of 102 CFU (50 μL−1. The detection time from the moment a sample was introduced to the display of the results was 1 h. To conclude, the portable impedance immunosensing system for detection of S. Typhimurium

  20. A development and integration analysis of commercial and in-house control subsystems

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.M. [Westinghouse Savannah River Co., Aiken, SC (United States); Dalesio, L.R. [Los Alamos National Lab., NM (United States)

    1998-12-31

    The acquisition and integration of commercial automation and control subsystems in physics research is becoming more common. It is presumed these systems present lower risk and less cost. This paper studies four subsystems used in the Accelerator Production of Tritium (APT) Low Energy Demonstration Accelerator (LEDA) at the Los Alamos National Laboratory (LANL). The radio frequency quadrupole (RFQ) resonance-control cooling subsystem (RCCS), the high-power RF subsystem and the RFQ vacuum subsystem were outsourced; the low-level RF (LLRF) subsystem was developed in-house. Based on the authors experience a careful evaluation of the costs and risks in acquisition, implementation, integration, and maintenance associated with these approaches is given.

  1. A self-consistent impedance method for electromagnetic surface impedance modeling

    Science.gov (United States)

    Thiel, David V.; Mittra, Raj

    2001-01-01

    A two-dimensional, self-consistent impedance method has been derived and used to calculate the electromagnetic surface impedance above buried objects at very low frequencies. The earth half space is discretized using an array of impedance elements. Inhomogeneities in the complex permittivity of the earth are reflected in variations in these impedance elements. The magnetic field is calculated for each cell in the solution space using a difference equation derived from Faraday's and Ampere's laws. It is necessary to include an air layer above the earth's surface to allow the scattered magnetic field to be calculated at the surface. The source field is applied above the earth's surface as a Dirichlet boundary condition, whereas the Neumann condition is employed at all other boundaries in the solution space. This, in turn, enables users to use both finite and infinite magnetic field sources as excitations. The technique is shown to be computationally efficient and yields reasonably accurate results when applied to a number of one- and two-dimensional earth structures with a known surface impedance distribution.

  2. Broadband electrical impedance matching for piezoelectric ultrasound transducers.

    Science.gov (United States)

    Huang, Haiying; Paramo, Daniel

    2011-12-01

    This paper presents a systematic method for designing broadband electrical impedance matching networks for piezoelectric ultrasound transducers. The design process involves three steps: 1) determine the equivalent circuit of the unmatched piezoelectric transducer based on its measured admittance; 2) design a set of impedance matching networks using a computerized Smith chart; and 3) establish the simulation model of the matched transducer to evaluate the gain and bandwidth of the impedance matching networks. The effectiveness of the presented approach is demonstrated through the design, implementation, and characterization of impedance matching networks for a broadband acoustic emission sensor. The impedance matching network improved the power of the acquired signal by 9 times.

  3. Bioelectrical Impedance Methods for Noninvasive Health Monitoring: A Review

    Directory of Open Access Journals (Sweden)

    Tushar Kanti Bera

    2014-01-01

    Full Text Available Under the alternating electrical excitation, biological tissues produce a complex electrical impedance which depends on tissue composition, structures, health status, and applied signal frequency, and hence the bioelectrical impedance methods can be utilized for noninvasive tissue characterization. As the impedance responses of these tissue parameters vary with frequencies of the applied signal, the impedance analysis conducted over a wide frequency band provides more information about the tissue interiors which help us to better understand the biological tissues anatomy, physiology, and pathology. Over past few decades, a number of impedance based noninvasive tissue characterization techniques such as bioelectrical impedance analysis (BIA, electrical impedance spectroscopy (EIS, electrical impedance plethysmography (IPG, impedance cardiography (ICG, and electrical impedance tomography (EIT have been proposed and a lot of research works have been conducted on these methods for noninvasive tissue characterization and disease diagnosis. In this paper BIA, EIS, IPG, ICG, and EIT techniques and their applications in different fields have been reviewed and technical perspective of these impedance methods has been presented. The working principles, applications, merits, and demerits of these methods has been discussed in detail along with their other technical issues followed by present status and future trends.

  4. Impedance pattern of vaginal and vestibular mucosa in cyclic goats

    Directory of Open Access Journals (Sweden)

    Ivo Křivánek

    2008-01-01

    Full Text Available The changes of vaginal and vestibular impedance during the oestrous cycle in goats were examined. The onset of oestrus was teased with a buck once a day during the experiment. Impedance was mea­sured by a four-terminal method. The vaginal impedance was recorded under slight pressure of electrodes to the vaginal dorsal wall at the cervix. The vestibular impedance was recorded under slight pressure of electrodes to the vestibular dorsal wall 5 cm from the vulva and at the vulva. The im­pe­dan­ce was measured once a day from 4 days before the expected oestrus to 6 days after onset of oestrus. The vaginal impedance at the cervix decreased during pro-oestrus (P < 0.01 and increased du­ring oestrus (P < 0.01. The vestibular impedance 5 cm from the vulva decreased during pro-oestrus (P < 0.01 and increased after oestrus (P < 0.01. The decrease of vaginal impedance during peri-oestrus was nearly twofold in comparison with the vestibular impedance 5 cm from the vulva. No sig­ni­fi­cant decrease of the vestibular impedance at the vulva was found during the oestrous cycle. The results indicate that the vaginal impedance at the cervix and vestibular impedance 5 cm from the vulva measured by means of a four-terminal method during the oestrous cycle display cyclic changes that are closely related to the oestrous behaviour of goats.

  5. Superconducting fault current-limiter with variable shunt impedance

    Science.gov (United States)

    Llambes, Juan Carlos H; Xiong, Xuming

    2013-11-19

    A superconducting fault current-limiter is provided, including a superconducting element configured to resistively or inductively limit a fault current, and one or more variable-impedance shunts electrically coupled in parallel with the superconducting element. The variable-impedance shunt(s) is configured to present a first impedance during a superconducting state of the superconducting element and a second impedance during a normal resistive state of the superconducting element. The superconducting element transitions from the superconducting state to the normal resistive state responsive to the fault current, and responsive thereto, the variable-impedance shunt(s) transitions from the first to the second impedance. The second impedance of the variable-impedance shunt(s) is a lower impedance than the first impedance, which facilitates current flow through the variable-impedance shunt(s) during a recovery transition of the superconducting element from the normal resistive state to the superconducting state, and thus, facilitates recovery of the superconducting element under load.

  6. A review of impedance measurements of whole cells.

    Science.gov (United States)

    Xu, Youchun; Xie, Xinwu; Duan, Yong; Wang, Lei; Cheng, Zhen; Cheng, Jing

    2016-03-15

    Impedance measurement of live biological cells is widely accepted as a label free, non-invasive and quantitative analytical method to assess cell status. This method is easy-to-use and flexible for device design and fabrication. In this review, three typical techniques for impedance measurement, i.e., electric cell-substrate impedance sensing, Impedance flow cytometry and electric impedance spectroscopy, are reviewed from the aspects of theory, to electrode design and fabrication, and applications. Benefiting from the integration of microelectronic and microfluidic techniques, impedance sensing methods have expanded their applications to nearly all aspects of biology, including living cell counting and analysis, cell biology research, cancer research, drug screening, and food and environmental safety monitoring. The integration with other techniques, the fabrication of devices for certain biological assays, and the development of point-of-need diagnosis devices is predicted to be future trend for impedance sensing techniques. Copyright © 2015 Elsevier B.V. All rights reserved.

  7. Characterization of Physiological Glucose Concentration Using Electrical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Quazi Delwar Hossain

    2013-01-01

    Full Text Available Non-invasive glucose monitoring is crucial for effective diabetes mellitus treatment while a sound correlation of a non-invasive parameter to glucose level variation is quite challenging. This paper presents characterization of glucose concentrations using Electrical Impedance Spectroscopy (EIS in three different solutions: 1 0.9% NaCl, 2 Saline (NaCl 1.3gm, KCl 0.75gm, Na3C6H5O7 1.45gm, D-glucose 6.75gm in 500mL and 3 Human Blood for every 25mg/dl change of glucose in total 150ml solution. A rectangular current pulse of 1.5s duration with 1mA peak is applied to the solutions and corresponding voltage is acquired across the solutions with Agilent InfiniiVision 7000B Series oscilloscope and Matlab R2011a Instrument Control Toolbox. The circuit proposed for current injection and voltage acquisition requires only two electrodes would reduce electrode polarization and skin irritation greatly which is a major concern in many previous works use generally four electrodes. Experimental results show sound correlation between EIS and blood glucose concentration. It is clearly found from the EIS that the DC impedance of solutions increases linearly with the increment in glucose concentrations.

  8. Design and evaluation of a low-level RF control system analog/digital receiver for the ILC main Linacs

    Energy Technology Data Exchange (ETDEWEB)

    Mavric, Uros; Vidmar, Matjaz; Chase, Brian; /Fermilab

    2008-06-01

    The proposed RF distribution scheme for the two 15 km long ILC LINACs, uses one klystron to feed 26 superconducting RF cavities operating at 1.3 GHz. For a precise control of the vector sum of the signals coming from the SC cavities, the control system needs a high performance, low cost, reliable and modular multichannel receiver. At Fermilab we developed a 96 channel, 1.3 GHz analog/digital receiver for the ILC LINAC LLRF control system. In the paper we present a balanced design approach to the specifications of each receiver section, the design choices made to fulfill the goals and a description of the prototyped system. The design is tested by measuring standard performance parameters, such as noise figure, linearity and temperature sensitivity. Measurements show that the design meets the specifications and it is comparable to other similar systems developed at other laboratories, in terms of performance.

  9. Design and evaluation of a low-level RF control system analog/digital receiver for the ILC main LINACs

    Energy Technology Data Exchange (ETDEWEB)

    Mavric, Uros [Fermilab, P.O. Box 500, 60510 Batavia, IL (United States)], E-mail: mavric@fnal.gov; Chase, Brian [Fermilab, P.O. Box 500, 60510 Batavia, IL (United States); Vidmar, Matjaz [Faculty of Electrical Engineering in Ljubljana, Trzaska 25, 1000 Ljubljana (Slovenia)

    2008-08-21

    The proposed RF distribution scheme for the two 15 km long ILC LINACs uses one klystron to feed 26 superconducting RF cavities operating at 1.3 GHz. For a precise control of the vector sum of the signals coming from the SC cavities, the control system needs a high-performance, low-cost, reliable and modular multichannel receiver. At Fermilab we developed a 96-channel, 1.3 GHz analog/digital receiver for the ILC LINAC LLRF control system. In this paper we present a balanced design approach to the specifications of each receiver section, the design choices made to fulfill the goals and a description of the prototyped system. The design is tested by measuring standard performance parameters, such as noise figure, linearity and temperature sensitivity. Measurements show that the design meets the specifications and it is comparable to other similar systems developed at other laboratories, in terms of performance.

  10. Impedance adaptation methods of the piezoelectric energy harvesting

    Science.gov (United States)

    Kim, Hyeoungwoo

    output power transferred to the small output load. Using this optimized DC-DC converter, two circuits used to light LEDs and charge battery were demonstrated. It was found that the power transferred to the loads was not the maximum power generated by a cymbal transducer because the loads were not matched to the energy source with the DC-DC converter even though the output power was significantly improved by DC-DC converter. An AC-DC converter with a piezoelectric transformer which has 98% efficiency was also studied to maximize the energy transfer to the load of 10˜100O. The output impedance was controlled by a piezoelectric transformer and the driving frequency of the transformer at resonance was adjusted by the AC-DC converter. A DC-DC converter was also used to stabilize the input power of the piezoelectric transformer. (Abstract shortened by UMI.)

  11. Automatic on-line analyser of microbial growth using simultaneous measurements of impedance and turbidity.

    Science.gov (United States)

    Madrid, R E; Felice, C J; Valentinuzzi, M E

    1999-11-01

    An apparatus for the measurement of bacterial growth is described. The instrument applies alternate adequate sequential currents of two different frequencies through a pair of electrodes immersed in a cultured medium. It monitors, detects and quantifies the growth of micro-organisms based on the measurement of the impedance across the two electrodes and, simultaneously, it measures the variation in the medium turbidity. The medium conductivity and the interface electrode impedance changes can be extracted from the measured impedance. The variations in turbidity can be calibrated in absorbance or optical density units. Moreover, all these parameters are also proportional to bacterial proliferation. The computer-controlled apparatus processes and displays the parameters on a monitor showing bulk resistance, electrode impedance and turbidity changes as time course events. The equipment can detect aerobic or anaerobic micro-organisms and permits the operator simultaneously to assess impedance and turbidity, or it can produce each parameter as a separate event. Time growth curves of different micro-organisms are presented in the results.

  12. Load monitoring of pin-connected structures using piezoelectric impedance measurement

    Science.gov (United States)

    Liang, Yabin; Li, Dongsheng; Parvasi, Seyed Mohammad; Song, Gangbing

    2016-10-01

    This paper presents a feasibility study on a developed impedance-based technique using Lead Zirconate Titanate patches for load monitoring of pin-connected structures, which are widely used in construction industry. The basic principle behind the load-monitoring technique is to utilize a high-frequency excitation signal (typically >30 kHz) through a surface-bonded piezoelectric sensor/actuator to detect changes in mechanical impedance of the structure due to the variations in structural loads. In order to verify the effectiveness of the developed technique, a tension-controllable structure with a pin connection was fabricated and investigated in this study. A load monitoring index was used to correlate the dominating peak frequency of the real part of the electrical impedance signature to the pin connection load. Experimental results obtained from twenty repeated tests prove that the proposed load-monitoring index increases as the load on the pin connection increases due to the enlarging true contact area of the pin connection. A 3D finite element method was also used to simulate and analyze the impedance signature of a pin connection model. Very good agreement exists between the numerical simulation’s results and the experimental results which demonstrates that the impedance-based technique can successfully be used to monitor the loading status of pin connections in practical applications.

  13. Studies of longitudinal profile of electron bunches and impedance measurements at Indus-2 synchrotron radiation source

    Science.gov (United States)

    Garg, Akash Deep; Yadav, S.; Kumar, Mukesh; Shrivastava, B. B.; Karnewar, A. K.; Ojha, A.; Puntambekar, T. A.

    2016-04-01

    Indus-2 is a 3rd generation synchrotron radiation source at the Raja Ramanna Centre for Advanced Technology (RRCAT) in India. We study the longitudinal profile of electrons in Indus-2 by using dual sweep synchroscan streak camera at visible diagnostic beamline. In this paper, the longitudinal profiles of electron bunch are analyzed by filling beam current in a single bunch mode. These studies are carried at injection energy (550 MeV) and at ramped beam energy (2.5 GeV). The effects of the wakefield generated interactions between the circulating electrons and the surrounding vacuum chamber are analyzed in terms of measured effects on longitudinal beam distribution. The impedance of the storage ring is obtained by fitting the solutions of Haissinski equation to the measured bunch lengthening with different impedance models. The impedance of storage ring obtained by a series R+L impedance model indicates a resistance (R) of 1350±125 Ω, an inductance (L) of 180±25 nH and broadband impedance of 2.69 Ω. These results are also compared with the values obtained from measured synchronous phase advancing and scaling laws. These studies are very useful in better understanding and control of the electromagnetic interactions.

  14. Design of a wearable perturbator for human knee impedance estimation during gait.

    Science.gov (United States)

    Tucker, Michael R; Moser, Adrian; Lambercy, Olivier; Sulzer, James; Gassert, Roger

    2013-06-01

    Mechanical impedance modulation is the key to natural, stable and efficient human locomotion. An improved understanding of this mechanism is necessary for the development of the next generation of intelligent prosthetic and orthotic devices. This paper documents the design methodologies that were employed to realize a knee perturbator that can experimentally estimate human knee impedance during gait through the application of angular velocity perturbations. The proposed experiment requires a light, transparent, wearable, and remotely actuated device that closely follows the movement of the biological joint. A genetic algorithm was used to design a polycentric hinge whose instantaneous center of rotation is optimized to be kinematically compatible with the human knee. A wafer disc clutch was designed to switch between a high transparency passive mode and a high impedance actuated mode. A remote actuation and transmission scheme was designed to enable high power output perturbations while minimizing the device's mass. Position and torque sensors were designed for device control and to provide data for post-processing and joint impedance estimation. Pending the fabrication and mechanical testing of the device, we expect this knee perturbator to be a valuable tool for experimental investigation of locomotive joint impedance modulation.

  15. A straightforward method for wall impedance eduction in a flow duct.

    Science.gov (United States)

    Jing, Xiaodong; Peng, Sen; Sun, Xiaofeng

    2008-07-01

    The development of the advanced liner technology for aeroengine noise control necessitates the impedance measurement method under realistic flow conditions. Currently, the methods for this need are mainly based on the inverse impedance eduction principle, confronting with the problems of initial guess, high computation cost, and low convergence. In view of this, a new strategy is developed that straightforwardly educes the impedance from the sound pressure information measured on the duct wall opposing to the test acoustic liner embedded in a flow duct. Here, the key insight is that the modal nature of the duct acoustic field renders a summed-exponential representation of the measured sound pressure; thus, the characterizing axial wave number can be readily extracted by means of Prony's method, and further the unknown impedance is calculated from the eigenvalue and dispersion relations based on the classical mode-decomposition analysis. This straightforward method is simple in its basic principle but remarkably has the advantages of ultimately overcoming the drawbacks inherent to the inverse methods, incorporating the realistic multimode nonprogressive wave effects, high computational efficiency, possibly reducing the measurement points, and even avoiding the necessity of the duct exit impedance that bothers perhaps all the existing waveguide methods.

  16. VOLTAMMETRY AND ELECTROCHEMICAL IMPEDANCE SPECTROSCOPY OF MEMBRANE SYSTEMS UNDER STABILIZED DIFFUSION LAYER THICKNESS

    Directory of Open Access Journals (Sweden)

    Sharafan M. V.

    2015-11-01

    Full Text Available The current-voltage characteristics and the number of effective ion transfer, as well as the frequency spectrum of the electrochemical impedance of multilayer ion-exchange membranes in a stable and controllable thickness of the diffusion layer were measured, using the of rotating membrane disk complex. The article presents a comparative analysis of the frequency spectra of the electrochemical impedance of the source and a surface-modified monopolar anion exchange membranes in 0.01 M sodium chloride was made. The process of water molecules dissociation at current densities above the limiting one in 0.01 M sodium chloride solution was studied in detail

  17. Research on Driving and Controlling of Ultrasonic Motor Based on Characteristic of Impedance Angle%基于阻抗角特性的超声电机驱动控制研究

    Institute of Scientific and Technical Information of China (English)

    雷向红; 曾劲松; 李伟

    2011-01-01

    驱动控制对于超声电机的推广和应用十分重要.根据超声波电机的工作特点,该文分析温度变化对超声电机运行状态的影响,开发了一种基于驱动电压和电流相位差的驱动控制器,分析了各个控制部分的作用和设计方法,并进行了比较实验,结果表明这种控制系统能够达到稳定超声电机运行状态的目的.%Driving and control techniques are very important for applications of ultrasonic motor.According to the work characteristics of ultrasonic motor, the influence of the temperature variety upon the movement status of ultrasonic motor was analyzed.A new controller based on the phase difference between the driving voltage and electric current was designed.Analyzed the function and design method of each control part,and carried on the compare experiment.Result show that this kinds of control system can attain the purpose of stabling the status of ultrasonic motor.

  18. Impedance analysis of an enhanced piezoelectric biosensor

    Science.gov (United States)

    Kim, Gi-Ho

    This study investigated the usefulness and characteristics of a five-megahertz quartz crystal resonator oscillating in a thickness-shear mode as a sensor of biological pathogens such as Salmonella typhimurium . An impedance analyzer measured the impedance of the oscillating quartz crystal, which determined all mechanical properties of the oscillating quartz and its immediate environment. In this study, the impedance behavior of the bare crystal was characterized in air and in potassium phosphate buffer solution. The potassium phosphate buffer was a Newtonian liquid. The resonance frequency of the oscillating quartz shifted down about 900 Hz by contacting with the buffer. An immobilized-antibody layer on the quartz surface behaved like a rigid mass when immersed in the buffer solution. The quartz crystal with immobilized antibodies was characterized in various solutions containing antibody- coated paramagnetic microspheres and varying concentrations of Salmonella typhimurium (102 - 108 cells/ml). The Salmonella cells were captured by antibody- coated paramagnetic microspheres, and then these complexes were moved magnetically to the oscillating quartz and were captured by antibodies immobilized on the crystal surface. The response of the crystal was expressed in terms of equivalent circuit parameters. The motional inductance and the motional resistance increased as a function of the concentration of Salmonella. The viscous damping was the main contribution to the resistance and the inductance in a liquid environment. The load resistance was the most effective and sensitive circuit parameter. A magnetic force was a useful method to collect the complexes of Salmonella-microspheres on the crystal surface and enhance the response sensor. In this system, the detection limit, based on resistance monitoring, was about 103 cells/ml.

  19. Visual basic for biomedical applications: tissue impedance and power delivery in an ESU system.

    Science.gov (United States)

    Bek, R

    1996-01-01

    The typical ESU found in most hospitals utilizes a microprocessor. This microprocessor supervises many tasks these include: time keeping, dosage monitoring, and display control. It must also perform complex tissue impedance measurement in real time as well as establishing a communication protocol to and from test hardware. This article will describe a means of displaying this information.

  20. Online Detection and Estimation of Grid Impedance Variation for Distributed Power Generation

    DEFF Research Database (Denmark)

    Jebali-Ben Ghorbal, Manel; Ghzaiel, Walid; Slama-Belkhodja, Ilhem;

    2012-01-01

    A better knowledge of the grid impedance is essential in order to improve power quality and control of the Distributed Power Generation Systems (DPGS) and also for a safe connection or reconnection to the utility grid. An LCL-filter associated to a Voltage Source Inverter (VSI) is usually used...

  1. Dynamic impedance model of the skin-electrode interface for transcutaneous electrical stimulation.

    Directory of Open Access Journals (Sweden)

    José Luis Vargas Luna

    Full Text Available Transcutaneous electrical stimulation can depolarize nerve or muscle cells applying impulses through electrodes attached on the skin. For these applications, the electrode-skin impedance is an important factor which influences effectiveness. Various models describe the interface using constant or current-depending resistive-capacitive equivalent circuit. Here, we develop a dynamic impedance model valid for a wide range stimulation intensities. The model considers electroporation and charge-dependent effects to describe the impedance variation, which allows to describe high-charge pulses. The parameters were adjusted based on rectangular, biphasic stimulation pulses generated by a stimulator, providing optionally current or voltage-controlled impulses, and applied through electrodes of different sizes. Both control methods deliver a different electrical field to the tissue, which is constant throughout the impulse duration for current-controlled mode or have a very current peak for voltage-controlled. The results show a predominant dependence in the current intensity in the case of both stimulation techniques that allows to keep a simple model. A verification simulation using the proposed dynamic model shows coefficient of determination of around 0.99 in both stimulation types. The presented method for fitting electrode-skin impedance can be simple extended to other stimulation waveforms and electrode configuration. Therefore, it can be embedded in optimization algorithms for designing electrical stimulation applications even for pulses with high charges and high current spikes.

  2. Inhibition of neuronal cell–cell adhesion measured by the microscopic aggregation assay and impedance sensing

    NARCIS (Netherlands)

    Wiertz, Remy; Marani, Enrico; Rutten, Wim

    2010-01-01

    Microscopic aggregation assay and impedance sensing (IS) were used to monitor a change in in vitro neuron–neuron adhesion in response to blocking of cell adhesion molecules. By blocking neuron–neuron adhesion, migration and aggregation of neuronal cells can be inhibited. This leads to better control

  3. Some boundary problems in electrical impedance tomography.

    Science.gov (United States)

    Pidcock, M; Ciulli, S; Ispas, S

    1996-11-01

    Accurate mathematical modelling is important in the development of iterative image reconstruction algorithms for electrical impedance tomography (EIT). In such schemes the forward problem of calculating the electric potential from Neumann boundary data is solved many times. One aspect of this problem which has received some attention is the mathematical modelling of the electrodes used in the technique. In this paper we describe an integral equation formulation of a boundary value problem associated with this tissue and we indicate some of the ways in which this formulation can be used to obtain numerical and analytic results.

  4. Method for conducting nonlinear electrochemical impedance spectroscopy

    Science.gov (United States)

    Adler, Stuart B.; Wilson, Jamie R.; Huff, Shawn L.; Schwartz, Daniel T.

    2015-06-02

    A method for conducting nonlinear electrochemical impedance spectroscopy. The method includes quantifying the nonlinear response of an electrochemical system by measuring higher-order current or voltage harmonics generated by moderate-amplitude sinusoidal current or voltage perturbations. The method involves acquisition of the response signal followed by time apodization and fast Fourier transformation of the data into the frequency domain, where the magnitude and phase of each harmonic signal can be readily quantified. The method can be implemented on a computer as a software program.

  5. Coupled Transmission Lines as Impedance Transformer

    DEFF Research Database (Denmark)

    Jensen, Thomas; Zhurbenko, Vitaliy; Krozer, Viktor

    2007-01-01

    A theoretical investigation of the use of a coupled line section as an impedance transformer is presented. We show how to properly select the terminations of the coupled line structures for effective matching of real and complex loads in both narrow and wide frequency ranges. The corresponding....... Wideband matching performance with relative bandwidth beyond 100% and return loss > 20 dB is demonstrated both theoretically and experimentally. Good agreement is achieved between the measured and predicted performance of the coupled line transformer section....

  6. LHC MD 232: Longitudinal Impedance Evaluation

    CERN Document Server

    Esteban Muller, Juan; Baudrenghien, Philippe; Shaposhnikova, Elena; CERN. Geneva. ATS Department

    2017-01-01

    The aim of the MDstudies presented here was to evaluate the imaginary part of the longitudinal impedance of the LHC by means of synchrotron frequency shift measurements. Single bunches with similar longitudinal emittance but different intensities were studied at flat top. Based on the beam parameters, a maximum shift of about 0.2 Hz was expected between the different bunches. A detailed analysis still needs to be carried out to determine the measured synchrotron frequency shift. The measurements took place between 8:00 p.m. on 26th and 2:00 a.m. on 27th July 2016

  7. Broadband Planar 5:1 Impedence Transformer

    Science.gov (United States)

    Ehsan, Negar; Hsieh, Wen-Ting; Moseley, Samuel H.; Wollack, Edward J.

    2015-01-01

    This paper presents a broadband Guanella-type planar impedance transformer that transforms so 50 omega to 10 omega with a 10 dB bandwidth of 1-14GHz. The transformer is designed on a flexible 50 micrometer thick polyimide substrate in microstrip and parallel-plate transmission line topologies, and is Inspired by the traditional 4:1 Guanella transformer. Back-to-back transformers were designed and fabricated for characterization in a 50 omega system. Simulated and measured results are in excellent agreement.

  8. Impedance matched thin metamaterials make metals absorbing.

    Science.gov (United States)

    Mattiucci, N; Bloemer, M J; Aközbek, N; D'Aguanno, G

    2013-11-13

    Metals are generally considered good reflectors over the entire electromagnetic spectrum up to their plasma frequency. Here we demonstrate an approach to tailor their absorbing characteristics based on the effective metamaterial properties of thin, periodic metallo-dielectric multilayers by exploiting a broadband, inherently non-resonant, surface impedance matching mechanism. Based on this mechanism, we design, fabricate and test omnidirectional, thin ( 99%) over a frequency range spanning from the UV to the IR. Our approach opens new venues to design cost effective materials for many applications such as thermo-photovoltaic energy conversion devices, light harvesting for solar cells, flat panel display, infrared detectors, stray light reduction, stealth and others.

  9. Resistor network approaches to electrical impedance tomography

    CERN Document Server

    Borcea, Liliana; Vasquez, Fernando Guevara; Mamonov, Alexander V

    2011-01-01

    We review a resistor network approach to the numerical solution of the inverse problem of electrical impedance tomography (EIT). The networks arise in the context of finite volume discretizations of the elliptic equation for the electric potential, on sparse and adaptively refined grids that we call optimal. The name refers to the fact that the grids give spectrally accurate approximations of the Dirichlet to Neumann map, the data in EIT. The fundamental feature of the optimal grids in inversion is that they connect the discrete inverse problem for resistor networks to the continuum EIT problem.

  10. Method for conducting nonlinear electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adler, Stuart B.; Wilson, Jamie R.; Huff, Shawn L.; Schwartz, Daniel T.

    2015-06-02

    A method for conducting nonlinear electrochemical impedance spectroscopy. The method includes quantifying the nonlinear response of an electrochemical system by measuring higher-order current or voltage harmonics generated by moderate-amplitude sinusoidal current or voltage perturbations. The method involves acquisition of the response signal followed by time apodization and fast Fourier transformation of the data into the frequency domain, where the magnitude and phase of each harmonic signal can be readily quantified. The method can be implemented on a computer as a software program.

  11. Metamaterial buffer for broadband non-resonant impedance matching of obliquely incident acoustic waves.

    Science.gov (United States)

    Fleury, Romain; Alù, Andrea

    2014-12-01

    Broadband impedance matching and zero reflection of acoustic waves at a planar interface between two natural materials is a rare phenomenon, unlike its optical counterpart, frequently observed for polarized light incident at the Brewster angle. In this article, it is shown that, by inserting a metamaterial layer between two acoustic materials with different impedance, it is possible to artificially realize an extremely broadband Brewster-like acoustic intromission angle window, in which energy is totally transmitted from one natural medium to the other. The metamaterial buffer, composed of acoustically hard materials with subwavelength tapered apertures, provides an interesting way to match the impedances of two media in a broadband fashion, different from traditional methods like quarter-wave matching or Fabry-Pérot resonances, inherently narrowband due to their resonant nature. This phenomenon may be interesting for a variety of applications including energy harvesting, acoustic imaging, ultrasonic transducer technology, and noise control.

  12. Characterisation of human skin impedance at acupuncture point PC4 Ximen and pericardium meridian using the four-electrode method.

    Science.gov (United States)

    Rezaei, Shima; Khorsand, Ali; Jamali, Jamshid

    2012-06-01

    Traditional Chinese medicine offers several theories to explain the mechanism of acupuncture. One of these theories proposes that acupuncture points and meridians have unique electrical properties and their electrical skin impedance is lower than surrounding areas. The aim of this study was to evaluate the differences in electrical skin impedance between PC4 and the pericardium meridian compared with the surrounding areas. Eighteen healthy subjects (10 women) were recruited to participate in the study. An impedance meter based on the four-electrode technique was designed specifically for the study. Twenty-five points were marked on the skin: one on the point PC4, four others on the pericardium meridian and 20 points around it. The electrical impedance of each point was measured with the four-electrode device. The mean electrical skin impedance at PC4 was significantly different from the 20 of the surrounding points but not significantly different from the four adjacent points. The mean skin impedance of the five points over the pericardium meridian was significantly different from that of parallel rows of points using repeated measures analysis of variance (ppericardium meridian is lower than surrounding areas, supporting the idea of different properties of the pericardium meridian compared with the control areas. Evidence on skin impedance at PC4 is inconclusive and further studies are needed.

  13. Skin impedance is not a factor in transcutaneous electrical nerve stimulation effectiveness

    Directory of Open Access Journals (Sweden)

    Vance CG

    2015-08-01

    Full Text Available Carol GT Vance,1 Barbara A Rakel,1,2 Dana L Dailey,1 Kathleen A Sluka1,2 1Department of Physical Therapy and Rehabilitation Science, University of Iowa Carver College of Medicine, 2University of Iowa, College Nursing Iowa City, IA, USA Objective: Transcutaneous electrical nerve stimulation (TENS is a nonpharmacological intervention used to manage pain using skin surface electrodes. Optimal electrode placement is unclear. We hypothesized that better analgesia would occur if electrodes were placed over sites with lower skin impedance. Optimal site selection (OSS and sham site selection (SSS electrode sites on the forearm were identified using a standard clinical technique. Methods: Experiment 1 measured skin impedance in the forearm at OSS and SSS. Experiment 2 was a crossover design double-blind randomized controlled trial comparing OSS-TENS, SSS-TENS, and placebo TENS (P-TENS to confirm differences in skin impedance between OSS and SSS, and measure change in pressure pain threshold (PPT following a 30-minute TENS treatment. Healthy volunteers were recruited (ten for Experiment 1 [five male, five female] and 24 for Experiment 2 [12 male, 12 female]. TENS was applied for 30 minutes at 100 Hz frequency, 100 µs pulse duration, and “strong but nonpainful” amplitude. Results: Experiment 1 results demonstrate significantly higher impedance at SSS (17.69±1.24 Ω compared to OSS (13.53±0.57 Ω (P=0.007. For Experiment 2, electrode site impedance was significantly higher over SSS, with both the impedance meter (P=0.001 and the TENS unit (P=0.012 compared to OSS. PPT change was significantly greater for both OSS-TENS (P=0.024 and SSS-TENS (P=0.025 when compared to P-TENS. PPT did not differ between the two active TENS treatments (P=0.81. Conclusion: Skin impedance is lower at sites characterized as optimal using the described technique of electrode site selection. When TENS is applied at adequate intensities, skin impedance is not a factor in

  14. Study on Impedance Characteristics of Aircraft Cables

    Directory of Open Access Journals (Sweden)

    Weilin Li

    2016-01-01

    Full Text Available Voltage decrease and power loss in distribution lines of aircraft electric power system are harmful to the normal operation of electrical equipment and may even threaten the safety of aircraft. This study investigates how the gap distance (the distance between aircraft cables and aircraft skin and voltage frequency (variable frequency power supply will be adopted for next generation aircraft will affect the impedance of aircraft cables. To be more precise, the forming mechanism of cable resistance and inductance is illustrated in detail and their changing trends with frequency and gap distance are analyzed with the help of electromagnetic theoretical analysis. An aircraft cable simulation model is built with Maxwell 2D and the simulation results are consistent with the conclusions drawn from the theoretical analysis. The changing trends of the four core parameters of interest are analyzed: resistance, inductance, reactance, and impedance. The research results can be used as reference for the applications in Variable Speed Variable Frequency (VSVF aircraft electric power system.

  15. Electrochemical Impedance Spectroscopy of Conductive Polymer Coatings

    Science.gov (United States)

    Calle, Luz Marina; MacDowell, Louis G.

    1996-01-01

    Electrochemical impedance spectroscopy (EIS) was used to investigate the corrosion protection performance of twenty nine proprietary conductive polymer coatings for cold rolled steel under immersion in 3.55 percent NaCl. Corrosion potential as well as Bode plots of the data were obtained for each coating after one hour immersion, All coatings, with the exception of one, have a corrosion potential that is higher in the positive direction than the corrosion potential of bare steel under the same conditions. Group A consisted of twenty one coatings with Bode plots indicative of the capacitive behavior characteristic of barrier coatings. An equivalent circuit consisting of a capacitor in series with a resistor simulated the experimental EIS data for these coatings very well. Group B consisted of eight coatings that exhibited EIS spectra showing an inflection point which indicates that two time constants are present. This may be caused by an electrochemical process taking place which could be indicitive of coating failing. These coatings have a lower impedance that those in Group A.

  16. AC Impedance Behaviour of Black Diamond Films

    Institute of Scientific and Technical Information of China (English)

    Haitao YE; Olivier GAUDIN; Richard B.JACKMAN

    2005-01-01

    The first measurement of impedance on free-standing diamond films from 0.1 Hz to 10 MHz up to 300℃ were reported. A wide range of chemical vapour deposition (CVD) materials were investigated, but here we concentrate are well fitted to a RC parallel circuit model and the equivalent resistance and capacitance for the diamond films have been estimated using the Zview curve fitting. The results show only one single semicircle response at each temperature measured. It was found that the resistance decreases from 62 MΩ at room temperature to 4 kΩ at300℃, with an activation energy around 0.51 eV. The equivalent capacitance is maintained at the level of 100 pF up to 300℃ suggesting that the diamond grain boundaries are dominating the conduction. At 400℃, the impedance at low frequencies shows a linear tail, which can be explained that the AC polarization of diamond/Au interface occurs.

  17. Galvanic apparent internal impedance: an intrinsic tissue property.

    Science.gov (United States)

    Golberg, Alex; Rabinowitch, Haim D; Rubinsky, Boris

    2009-11-01

    Using basic galvanic cell principles, the ability of tissues to generate electrical current through electrolysis was characterized. Studying Zn/Cu electrolysis in animal organs revealed a fundamental and measurable tissue-specific property - the galvanic apparent internal impedance (GAII), that is most likely related to the salt bridge function of tissues delineated by electrodes. Further to the fundamental knowledge acquired, GAII enables a new diagnostic method to distinguish between tissue types and to determine their health status without a need for expensive calibration, as often required when external power source is used. We demonstrated the GAII sensitivity in detecting tissue ablation with microwave heating or irreversible electroporation. The results open the way for a novel, inexpensive self-powered tissue diagnostic system for a wide range of applications such as minimally invasive tissue health status, ischemia, hydration, real time intra-operative control of minimally invasive surgery, medical imaging, virtual biopsy and many others.

  18. Multispectral Electrical Impedance Tomography using Optimization over Manifolds

    Science.gov (United States)

    Fouchard, A.; Bonnet, S.; David, O.

    2016-10-01

    Electrical impedance tomography under spectral constraints uses a material basis decomposition to combine the different information embedded in the tissue spectra. This approach offers an alternative to static imaging while benefiting from systemic error cancellation using difference data. It suits well cases where no prior solution is known and the contrast lies entirely between frequencies, e.g. to diagnose acute stroke or cancer. In this work, a computational framework is presented to deal with the extra frequency dimensions and the constraints during reconstruction. A fraction volume approach is demonstrated with explicit Euclidean gradient, usage of a finite volume element solver and minimization over the oblique manifold. It is applied to synthetic data. Parameter estimations are compared between a monofrequency inversion and the proposed multispectral implementation. Results suggest that the proposed workflow enables to reduce the computational workload of multispectral inversion while ensuring valid proportions of materials within each control volume.

  19. Study on electrical impedance matching for broadband ultrasonic transducer

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Geon Woo [University of Science and Technology, Daejeon (Korea, Republic of); Kim, Ki Bok [Korea Research Institute of Standards and Science, Center for Safety Measurement, Daejeon (Korea, Republic of); Baek, Kwang Sae [Elache Co., Busan (Korea, Republic of)

    2017-02-15

    Ultrasonic transducers with high resolution and resonant frequency are required to detect small defects (less than hundreds of μm) by ultrasonic testing. The resonance frequency and resolution of an ultrasonic transducer are closely related to the thickness of piezo-electric materials, backing materials, and the electric impedance matching technique. Among these factors, electrical impedance matching plays an important role because it can reduce the loss and reflection of ultrasonic energy differences in electrical impedance between an ultrasonic transducer and an ultrasonic defects detecting system. An LC matching circuit is the most frequently used electric matching method. It is necessary for the electrical impedance of an ultrasonic transducer to correspond to approximately 50 Ω to compensate the difference in electrical impedance between both connections. In this study, a 15 MHz immersion ultrasonic transducer was fabricated and an LC electrical impedance circuit was applied to that for having broad-band frequency characteristic.

  20. Transverse impedance measurement in RHIC and the AGS

    Energy Technology Data Exchange (ETDEWEB)

    Biancacci, Nicolo [European Organization for Nuclear Research (CERN), Geneva (Switzerland); Blaskiewicz, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Dutheil, Y. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Liu, C. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Mernick, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; Minty, M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.; White, S. M. [Brookhaven National Lab. (BNL), Upton, NY (United States). Collider-Accelerator Dept.

    2014-05-12

    The RHIC luminosity upgrade program aims for an increase of the polarized proton luminosity by a factor 2. To achieve this goal a significant increase in the beam intensity is foreseen. The beam coupling impedance could therefore represent a source of detrimental effects for beam quality and stability at high bunch intensities. For this reason it is essential to quantify the accelerator impedance budget and the major impedance sources, and possibly cure them. In this MD note we summarize the results of the 2013 transverse impedance measurements in the AGS and RHIC. The studies have been performed measuring the tune shift as a function of bunch intensity and deriving the total accelerator machine transverse impedance. For RHIC, we could obtain first promising results of impedance localization measurements as well.

  1. Breathing detection with a portable impedance measurement system: first measurements.

    Science.gov (United States)

    Cordes, Axel; Foussier, Jerome; Leonhardt, Steffen

    2009-01-01

    For monitoring the health status of individuals, detection of breathing and heart activity is important. From an electrical point of view, it is known that breathing and heart activity change the electrical impedance distribution in the human body over the time due to ventilation (high impedance) and blood shifts (low impedance). Thus, it is possible to detect both important vital parameters by measuring the impedance of the thorax or the region around lung and heart. For some measurement scenarios it is also essential to detect these parameters contactless. For instance, monitoring bus drivers health could help to limit accidents, but directly connected systems limit the drivers free moving space. One measurement technology for measuring the impedance changes in the chest without cables is the magnetic impedance tomography (MIT). This article describes a portable measurement system we developed for this scenario that allows to measure breathing contactless. Furthermore, first measurements with five volunteers were performed and analyzed.

  2. 8-channel, FPGA based, DSP integrated cavity simulator and controller for VUV-FEL. SIMCON 3.0 Ver. 3.0. rev. 1, 06.2005 - Hardware manual

    Energy Technology Data Exchange (ETDEWEB)

    Pozniak, K.T.; Czarski, T.; Koprek, W.; Giergusiewicz, W.; Romaniuk, R.S. [Warsaw Univ. of Technology (Poland). Inst. of Electronic Systems ELHEP Laboratory

    2005-07-01

    The note describes integrated, eight channel system of hardware controller and simulator of the resonant superconducting, narrowband niobium cavity, originally considered for the TTF and TESLA in DESY, Hamburg (now tested for the VUV FEL and developed for X-Ray FEL). The controller bases on a programmable circuit Xilinx VirtexII V4000. The solution uses DSP EMBEDDED BOARD module positioned on a Modular LLRF Control Platform. The algorithm and FPGA circuit configuration was done in the VHDL language. The internal hardware multiplication components, present in Virtex II chips, were used, to improve the floating point calculation efficiency. The implementation was achieved of a device working in the real time, according to the demands of the LLRF control system for the TESLA Test Facility (now associated with the VUV FEL machine). The device under consideration will be referred to as superconducting cavity (SCCav) SIMCON throughout this work. The manual describes hardware features of SIMCON, ver. 3.0 in modular solution. The following components are described here in detail: functional layer, parameter programming, foundations of control of particular blocks and monitoring of the real time processes. This note is accompanied by the one describing the multichannel DOOCS interface for the described hardware system. The interface was prepared in DOOCS for Solaris and in Windows. The hardware and software of 8-channel SIMCON was tested in CHECIA and ACC1 module of VUV FEL linac. The measurements results are presented. While giving all necessary technical details required to understand the work of the integrated hardware controller and simulator and to enable its practical copying, this document is a unity with other TESLA technical notes published by the same team on the subject. Thus, some modeling and other subjects were omitted, as they were addressed in detail in the quoted references. Keywords: Super conducting cavity, cavity simulator, CAVITIES CONTROLLER, SIMCON

  3. Detection of 1,5-Anhydroglucitol by Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Adamson, Teagan L.; Cook, Curtiss B.

    2014-01-01

    Multiple markers are used to assess glycemic control in patients with diabetes mellitus (DM). New technology that permits simultaneous detection of multiple biomarkers combined with those used at the point of care indicative of glycemic control, including glycemic variability determined from 1,5-anhydroglucitol measurement, could provide better management and further insight into the disease. This platform was based on previous research involving glucose detection and uses electrochemical impedance spectroscopy to detect a range of 1,5-anhydroglucitol concentrations at an optimal binding frequency. The enzyme pyranose oxidase was fixed to gold electrodes while a sine wave of sweeping frequencies was induced in purified solutions and in variable presence of whole blood. The optimal binding frequency for the detection of 1,5-anhydroglucitol was found to be 3.71 kHz. The impedance response compared to the concentration of target present was found to have a logarithmic slope of 7.04 with an R-squared value of 0.96. This response includes 2 experimental sets, a single test of a low concentration range and a high concentration range with 5 replicates. The relative standard deviation of the high range varied from 28% to 27% from lowest to highest concentrations. Best detection in complex solutions was found in lower blood concentrations of 0.5% and 1%, but maintained relatively high accuracy in concentrations 5% and 10%. The sensor platform was successfully evaluated at a high dynamic range of 1,5-AG in purified solutions. In the presence of whole blood, lowest percentages yielded the best results indicating that filtering interferents may be necessary in final device architecture. PMID:24876587

  4. Reciprocity and mutual impedance formulas within lossy cavities

    Directory of Open Access Journals (Sweden)

    F. Gronwald

    2005-01-01

    Full Text Available We discuss the validity of reciprocity and mutual impedance formulas within lossy cavities. Mutual impedance formulas are well-known from antenna theory and useful to describe the electromagnetic coupling between electromagnetic interference sources and victims. As an example the mutual impedance between two dipole antennas within a lossy rectangular cavity is calculated from a system of coupled Hallén's equations that efficiently is solved by the method of moments.

  5. Line Impedance Estimation Using Active and Reactive Power Variations

    DEFF Research Database (Denmark)

    Timbus, Adrian Vasile; Rodriguez, Pedro; Teodorescu, Remus;

    2007-01-01

    This paper proposes an estimation method of power system impedance based on power variations caused by a distributed power generation system (DPGS) at the point of common coupling (PCC). The proposed algorithm is computationally simple and uses the voltage variations at the point of common coupling...... (PCC) caused by the variations of the power delivered to utility network to derive the value of grid impedance. Accurate estimation of both resistive and inductive part of the impedance is obtained, as the results presented show....

  6. Evaluation of body composition in COPD patients using multifrequency bioelectrical impedance analysis

    Science.gov (United States)

    de Blasio, Francesca; de Blasio, Francesco; Miracco Berlingieri, Giulia; Bianco, Andrea; La Greca, Marta; Franssen, Frits M E; Scalfi, Luca

    2016-01-01

    Background Multifrequency bioelectrical impedance analysis (MF-BIA) is a technique that measures body impedance (Z) at different frequencies (5, 10, 50, 100, and 250 kHz). Body composition may be estimated using empirical equations, which include BIA variables or, alternatively, raw BIA data may provide direct information on water distribution and muscle quality. Objectives To compare raw MF-BIA data between COPD patients and controls and to study their relationship with respiratory and functional parameters in COPD patients. Methods MF-BIA was performed (Human Im-Touch analyzer) in 212 COPD patients and 115 age- and BMI-matched controls. Fat-free mass (FFM) and fat mass were estimated from BIA data, and low- to high-frequency (5 kHz/250 kHz) impedance ratio was calculated. Physical fitness, lung function and respiratory muscle strength were also assessed in COPD patients. Results After adjusting for age, weight, and body mass index, FFM and the 5/250 impedance ratio were lower in COPD patients (P<0.001) and were negatively affected by disease severity. In both male and female patients, the 5/250 impedance ratio was significantly correlated mainly with age (r=−0.316 and r=−0.346, respectively). Patients with a 5/250 impedance ratio below median value had lower handgrip strength (P<0.001), 6-minute walk distance (P<0.005), respiratory muscle strength (P<0.005), forced expiratory volume in 1 second (P<0.05) and vital capacity (P<0.005). Finally, the 5/250 impedance ratio was reduced (P<0.05) in patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) III and IV (compared to those with GOLD I and II) or a BODE index between 6 and 10 points (compared to those with BODE index between 1 and 5 points). Conclusion MF-BIA may be a useful tool for assessing body composition and nutritional status in COPD patients. In particular, the impedance ratio could give valuable information on cellular integrity and muscle quality.

  7. Impedance Localization Measurements using AC Dipoles in the LHC

    CERN Document Server

    Biancacci, Nicolo; Papotti, Giulia; Persson, Tobias; Salvant, Benoit; Tomás, Rogelio

    2016-01-01

    The knowledge of the LHC impedance is of primary importance to predict the machine performance and allow for the HL-LHC upgrade. The developed impedance model can be benchmarked with beam measurements in order to assess its validity and limit. This is routinely done, for example, moving the LHC collimator jaws and measuring the induced tune shift. In order to localize possible unknown impedance sources, the variation of phase advance with intensity between beam position monitors can be measured. In this work we will present the impedance localization measurements performed at injection in the LHC using AC dipoles as exciter as well as the underlying theory.

  8. Iterative Reconstruction Methods for Hybrid Inverse Problems in Impedance Tomography

    DEFF Research Database (Denmark)

    Hoffmann, Kristoffer; Knudsen, Kim

    2014-01-01

    For a general formulation of hybrid inverse problems in impedance tomography the Picard and Newton iterative schemes are adapted and four iterative reconstruction algorithms are developed. The general problem formulation includes several existing hybrid imaging modalities such as current density...... impedance imaging, magnetic resonance electrical impedance tomography, and ultrasound modulated electrical impedance tomography, and the unified approach to the reconstruction problem encompasses several algorithms suggested in the literature. The four proposed algorithms are implemented numerically in two...... be based on a theoretical analysis of the underlying inverse problem....

  9. Simulation of the low-frequency collimator impedance

    CERN Document Server

    Kroyer, T

    2008-01-01

    The low-frequency transverse collimator impedance constitutes a major part of the LHC impedance budget. In this paper numerical simulations for frequencies below 1 MHz using a commercial package are presented. From the 3D field solution of the two-wire simulations the transverse impedance is directly calculated. After a cross-check with theory for rotationally symmetric structures a geometry with two jaws and an LHC graphite collimator is examined. Furthermore, a simple physics picture that explains the principal characteristics of the impedance at high and low frequencies is given.

  10. Frequency Bandwidth of Half-Wave Impedance Repeater

    Directory of Open Access Journals (Sweden)

    Marek Dvorsky

    2012-01-01

    Full Text Available This article brings in the second part general information about half-wave impedance repeater. The third part describes the basic functional principles of the half-wave impedance repeater using Smith chart. The main attention is focused in part four on the derivation of repeater frequency bandwidth depending on characteristics and load impedance of unknown feeder line. Derived dependences are based on the elementary features of the feeder lines with specific length. The described functionality is proved in part 4.3 by measurement of transformed impedance using vector several unbalanced feeder lines and network analyzer VNWA3+.

  11. Impedance of the PEP-II DIP screen

    Energy Technology Data Exchange (ETDEWEB)

    Ng, C.-K. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Weiland, T.

    1996-08-01

    The vacuum chamber of a storage ring normally consists of periodically spaced pumping slots. The longitudinal impedance of slots are analyzed in this paper. It is found that although the broad-band impedance is tolerable, the narrow-band impedance, as a consequence of the periodicity of the slots, may exceed the stability limit given by natural damping with no feedback system on. Based on this analysis, the PEP-II distributed-ion-pump (DIP) screen uses long grooves with hidden holes cut halfway to reduce both the broad-band and narrow-band impedances. (author)

  12. Esophageal impedance baseline according to different time intervals

    Directory of Open Access Journals (Sweden)

    Ummarino Dario

    2012-06-01

    Full Text Available Abstract Background The impedance baseline has been shown to reflect esophageal integrity, and to be decreased in patients with esophagitis. However, different methods for the determination of the impedance baseline have not been compared. Methods The median impedance baseline was calculated in 10 consecutive multichannel intraluminal impedance recordings in children with non-erosive reflux disease. All children underwent an endoscopy with a biopsy as part of the clinical work-up to exclude esophagitis. The impedance baseline was obtained both by including and excluding all impedance episodes (IE; reflux, swallows and gas episodes during the full recording, and during the first 1-minute period without an IE every hour (method 1, every 2 hours (method 2 or every 4 hours (method 3. The impedance baseline obtained during the full recording was set at 100%, and the variation (difference in impedance baseline for the different methods and variability (difference in impedance baseline during one analysis period were assessed. Results None of the participants had esophagitis. The mean difference over the six channels between the impedance baseline over the total recording with and without IE was approximately 2.5%, and comparable for each channel (range 0.47% to 5.55%. A mean of 1,028 IEs were excluded in each tracing, and it took between 4 and 24 hours to delete all events in one tracing. The difference in the impedance baseline obtained with and without IEs was mainly caused by the gas episodes in the upper channels and swallows in the lower channels. The median impedance baseline according to the three one-minute analysis methods was comparable to the median impedance baseline according to the 24 hour analysis. Conclusions The automatic determination of the median impedance baseline over the total tracing including IEs is an adequate method. In isolated tracings with numerous IEs, the calculation of the median impedance baseline over one minute

  13. Impedance cardiography – optimization and efficacy evaluation of antihypertensive treatment

    National Research Council Canada - National Science Library

    Panasiuk-Kamińska, Katarzyna; Szeliga-Król, Jolanta; Zubilewicz, Renata; Jaroszyński, Andrzej

    2016-01-01

    ...% are treated effectively. Impedance cardiography (IC) is an important tool both in diagnostics and the treatment of hypertensive patients, particularly in the case of antihypertensive treatment resistance...

  14. Novel method for planar microstrip antenna matching impedance

    CERN Document Server

    Ali, Mahdi; Samet, Mounir

    2010-01-01

    Because all microstrip antennas have to be matched to the standard generator impedance or load, the input impedance matching method for antenna is particularly important. In this paper a new methodology in achieving matching impedance of a planar microstrip antenna for wireless application is described. The method is based on embedding an Interdigital capacitor. The fine results obtained by using a microstrip Interdigital capacitor for matching antenna impedance led to an efficient method to improve array antenna performance. In fact, a substantial saving on the whole surfaces as well as enhancement of the gain, the directivity and the power radiated was achieved.

  15. Electrochemical Impedance of a Battery Electrode with Anisotropic Active Particles

    CERN Document Server

    Song, J

    2013-01-01

    Electrochemical impedance spectra for battery electrodes are usually interpreted using models that assume isotropic active particles, having uniform current density and symmetric diffusivities. While this can be reasonable for amorphous or polycrystalline materials with randomly oriented grains, modern electrode materials increasingly consist of highly anisotropic, single-crystalline, nanoparticles, with different impedance characteristics. In this paper, analytical expressions are derived for the impedance of anisotropic particles with tensorial diffusivities and orientation-dependent surface reaction rates and capacitances. The resulting impedance spectrum contains clear signatures of the anisotropic material properties and aspect ratio, as well as statistical variations in any of these parameters.

  16. Impedance of SOFC electrodes: A review and a comprehensive case study on the impedance of LSM:YSZ cathodes

    DEFF Research Database (Denmark)

    Nielsen, Jimmi; Hjelm, Johan

    2014-01-01

    It was shown through a comprehensive impedance spectroscopy study that the impedance of the classic composite LSM:YSZ (lanthanum strontium manganite and yttria stabilized zirconia) solid oxide fuel cell (SOFC) cathode can be described well with porous electrode theory. Furthermore, it was illustr......It was shown through a comprehensive impedance spectroscopy study that the impedance of the classic composite LSM:YSZ (lanthanum strontium manganite and yttria stabilized zirconia) solid oxide fuel cell (SOFC) cathode can be described well with porous electrode theory. Furthermore...... acquired in the very broad temperature range of 200–900°C for complete elucidation of the impedance. All impedance spectra were analyzed in terms of porous electrode theory. Physical materials parameters were extracted from the analysis, which were in excellent accordance with literature values. Valuable...

  17. Magnetically Coupled Impedance-Source Inverters

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Blaabjerg, Frede

    2013-01-01

    input-to-output gain and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters, most of which are linked to their requirement for low modulation ratio at high...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology...

  18. Magnetically coupled impedance-source inverters

    DEFF Research Database (Denmark)

    Loh, Poh Chiang; Blaabjerg, Frede

    2012-01-01

    input-to-output gain, and the presence of an impedance network. The former means a high dc-link voltage, which can stress the semiconductor switches unnecessarily. The latter leads to increases in cost and size, which similarly are undesirable. To lessen these concerns, an interesting approach is to use......Z-source inverters are a new class of inverters proposed with output voltage or current buck-boost ability. Despite their general attractiveness, there are some present limitations faced by existing Z-source inverters. Most of which are linked to their requirement for low modulation ratio at high...... magnetically coupled transformers or inductors to raise the gain and modulation ratio simultaneously, while reducing the number of passive components needed. A study of the approach is now presented to show how various existing magnetically coupled inverters can be derived by applying a generic methodology...

  19. The sensitivity in Electrical Impedance Tomography

    Directory of Open Access Journals (Sweden)

    A. I. Rybin

    2013-12-01

    Full Text Available Introduction. The concept of sensitivity in Electrical Impedance Tomography is introduced (first – fourth type. The experimental researches measuring the voltages on the phantom outline are conducted on the created layout (for uniform cylindrical vessel with brine and placed inhomogeneities in a vessel. The main part. The inverse problems are solved for simulated on PC phantom (the third type sensitivity and from measured results (the fourth type sensitivity by conductivity zones method using regularization by A. Tykhonov. The sensitivity to conductivity increasing of elements inside the phantom is significantly less than the sensitivity to resistance increasing. The results of measured voltages processing and the results of projection reconstruction (obtained from mathematical model and from measured results are described. Conclusions. The satisfactory agreements of reconstruction results between themselves and with mathematical and measured phantoms are shown.

  20. Sensing Estrogen with Electrochemical Impedance Spectroscopy

    Science.gov (United States)

    Li, Jing; Kim, Byung Kun; Im, Ji-Eun; Choi, Han Nim; Kim, Dong-Hwan; Cho, Seong In

    2016-01-01

    This study demonstrates the application feasibility of electrochemical impedance spectroscopy (EIS) in measuring estrogen (17β-estradiol) in gas phase. The present biosensor gives a linear response (R2 = 0.999) for 17β-estradiol vapor concentration from 3.7 ng/L to 3.7 × 10−4 ng/L with a limit of detection (3.7 × 10−4 ng/L). The results show that the fabricated biosensor demonstrates better detection limit of 17β-estradiol in gas phase than the previous report with GC-MS method. This estrogen biosensor has many potential applications for on-site detection of a variety of endocrine disrupting compounds (EDCs) in the gas phase.

  1. Quartz tuning fork based microwave impedance microscopy

    Science.gov (United States)

    Cui, Yong-Tao; Ma, Eric Yue; Shen, Zhi-Xun

    2016-06-01

    Microwave impedance microscopy (MIM), a near-field microwave scanning probe technique, has become a powerful tool to characterize local electrical responses in solid state samples. We present the design of a new type of MIM sensor based on quartz tuning fork and electrochemically etched thin metal wires. Due to a higher aspect ratio tip and integration with tuning fork, such design achieves comparable MIM performance and enables easy self-sensing topography feedback in situations where the conventional optical feedback mechanism is not available, thus is complementary to microfabricated shielded stripline-type probes. The new design also enables stable differential mode MIM detection and multiple-frequency MIM measurements with a single sensor.

  2. The vacuum impedance and unit systems

    CERN Document Server

    Kitano, M

    2006-01-01

    In electromagnetism, the vacuum impedance $Z_0$ is a universal constant, which is as important as the velocity of light $c$ in vacuum. Unfortunately, however, its significance does not seem to be appreciated so well and sometimes the presence itself is ignored. It is partly because in the Gaussian system of units, which has widely been used for long time, $Z_0$ is a dimensionless constant and of unit magnitude. In this paper, we clarify that $Z_0$ is a fundamental parameter in electromagnetism and plays major roles in the following scenes: reorganizing the structure of the electromagnetic formula in reference to the relativity; renormalizing the quantities toward natural unit systems starting from the SI unit system; and defining the magnitudes of electromagnetic units.

  3. Sensing Estrogen with Electrochemical Impedance Spectroscopy

    Directory of Open Access Journals (Sweden)

    Jing Li

    2016-01-01

    Full Text Available This study demonstrates the application feasibility of electrochemical impedance spectroscopy (EIS in measuring estrogen (17β-estradiol in gas phase. The present biosensor gives a linear response (R2=0.999 for 17β-estradiol vapor concentration from 3.7 ng/L to 3.7 × 10−4 ng/L with a limit of detection (3.7 × 10−4 ng/L. The results show that the fabricated biosensor demonstrates better detection limit of 17β-estradiol in gas phase than the previous report with GC-MS method. This estrogen biosensor has many potential applications for on-site detection of a variety of endocrine disrupting compounds (EDCs in the gas phase.

  4. Comparative study of electrolyte additives using electrochemical impedance spectroscopy on symmetric cells

    Science.gov (United States)

    Petibon, R.; Sinha, N. N.; Burns, J. C.; Aiken, C. P.; Ye, Hui; VanElzen, Collette M.; Jain, Gaurav; Trussler, S.; Dahn, J. R.

    2014-04-01

    The effect of various electrolyte additives and additive combinations added to a 1 M LiPF6 EC:EMC electrolyte on the positive and negative electrodes surface of 1 year old wound LiCoO2/graphite cells and Li[Ni0.4Mn0.4Co0.2])O2/graphite cells was studied using electrochemical impedance spectroscopy (EIS) on symmetric cells. The additives tested were: vinylene carbonate (VC), trimethoxyboroxine (TMOBX), fluoroethylene carbonate (FEC), lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), and H2O alone or in combination. In general, compared to control electrolyte, the additives tested reduced the impedance of the positive electrode and increased the impedance of the negative electrode with the exception of LiTFSI in Li[Ni0.4Mn0.4Co0.2]O2/graphite wound cells. Higher charge voltage led to higher positive electrode impedance, with the exception of 2%VC + 2% FEC, and 2% LiTFSI. In some cases, some additives when mixed with another controlled the formation of the SEI at one electrode, and shared the formation of the SEI at one electrode when mixed with a different additive.

  5. Relating membrane potential to impedance spectroscopy

    Directory of Open Access Journals (Sweden)

    Eugen Gheorghiu

    2011-12-01

    Full Text Available Non-invasive, label-free assessment of membrane potential of living cells is still a challenging task. The theory linking membrane potential to the low frequency α dispersion exhibited by suspensions of spherical shelled particles (presenting a net charge distribution on the inner side of the shell has been pioneered in our previous studies with emphasis on the permittivity spectra. Whereas α dispersion is related to a rather large variation exhibited by the permittivity spectrum, we report that the related decrement presented by the impedance magnitude spectrum is either extremely small, or occurs (for large cells at very small frequencies (~mHz explaining the lack of experimental bioimpedance data on the matter. We stress that appropriate choice of the parameters (as revealed by the microscopic model may enable access to membrane potential as well as to other relevant parameters when investigating living cells and charged lipid vesicles. We analyse the effect on the low frequency of the permittivity and impedance spectra of: I. Parameters pertaining to cell membrane i.e. (i membrane potential (through the amount of the net charge on the inner side of the membrane, (ii size of the cells/vesicles, (iii conductivity of the membrane; II. Parameters of the extra cellular medium (viscosity and conductivity. The applicability of the study has far reaching implications for basic (life sciences (providing non-invasive access to the dynamics of relevant cell parameters as well as for biosensing applications, e.g. assessment of cytotoxicity of a wide range of stimuli. doi:10.5617/jeb.214 J Electr Bioimp, vol. 2, pp. 93-97, 2011

  6. An Electronic Measurement Instrumentation of the Impedance of a Loaded Fuel Cell or Battery

    Science.gov (United States)

    Aglzim, El-Hassane; Rouane, Amar; El-Moznine, Reddad

    2007-01-01

    In this paper we present an inexpensive electronic measurement instrumentation developed in our laboratory, to measure and plot the impedance of a loaded fuel cell or battery. Impedance measurements were taken by using the load modulation method. This instrumentation has been developed around a VXI system stand which controls electronic cards. Software under Hpvee® was developed for automatic measurements and the layout of the impedance of the fuel cell on load. The measurement environment, like the ambient temperature, the fuel cell temperature, the level of the hydrogen, etc…, were taken with several sensors that enable us to control the measurement. To filter the noise and the influence of the 50Hz, we have implemented a synchronous detection which filters in a very narrow way around the useful signal. The theoretical result obtained by a simulation under Pspice® of the method used consolidates the choice of this method and the possibility of obtaining correct and exploitable results. The experimental results are preliminary results on a 12V vehicle battery, having an inrush current of 330A and a capacity of 40Ah (impedance measurements on a fuel cell are in progress, and will be the subject of a forthcoming paper). The results were plotted at various nominal voltages of the battery (12.7V, 10V, 8V and 5V) and with two imposed currents (0.6A and 4A). The Nyquist diagram resulting from the experimental data enable us to show an influence of the load of the battery on its internal impedance. The similitude in the graph form and in order of magnitude of the values obtained (both theoretical and practical) enables us to validate our electronic measurement instrumentation. One of the future uses for this instrumentation is to integrate it with several control sensors, on a vehicle as an embedded system to monitor the degradation of fuel cell membranes.

  7. Electrical impedance spectroscopy for measuring the impedance response of carbon-fiber-reinforced polymer composite laminates

    KAUST Repository

    Almuhammadi, Khaled

    2017-02-16

    Techniques that monitor the change in the electrical properties of materials are promising for both non-destructive testing and structural health monitoring of carbon-fiber-reinforced polymers (CFRPs). However, achieving reliable monitoring using these techniques requires an in-depth understanding of the impedance response of these materials when subjected to an alternating electrical excitation, information that is only partially available in the literature. In this work, we investigate the electrical impedance spectroscopy response at various frequencies of laminates chosen to be representative of classical layups employed in composite structures. We clarify the relationship between the frequency of the electrical current, the conductivity of the surface ply and the probing depth for different CFRP configurations for more efficient electrical signal-based inspections. We also investigate the effect of the amplitude of the input signal.

  8. Aircraft panel with sensorless active sound power reduction capabilities through virtual mechanical impedances

    Science.gov (United States)

    Boulandet, R.; Michau, M.; Micheau, P.; Berry, A.

    2016-01-01

    This paper deals with an active structural acoustic control approach to reduce the transmission of tonal noise in aircraft cabins. The focus is on the practical implementation of the virtual mechanical impedances method by using sensoriactuators instead of conventional control units composed of separate sensors and actuators. The experimental setup includes two sensoriactuators developed from the electrodynamic inertial exciter and distributed over an aircraft trim panel which is subject to a time-harmonic diffuse sound field. The target mechanical impedances are first defined by solving a linear optimization problem from sound power measurements before being applied to the test panel using a complex envelope controller. Measured data are compared to results obtained with sensor-actuator pairs consisting of an accelerometer and an inertial exciter, particularly as regards sound power reduction. It is shown that the two types of control unit provide similar performance, and that here virtual impedance control stands apart from conventional active damping. In particular, it is clear from this study that extra vibrational energy must be provided by the actuators for optimal sound power reduction, mainly due to the high structural damping in the aircraft trim panel. Concluding remarks on the benefits of using these electrodynamic sensoriactuators to control tonal disturbances are also provided.

  9. Using active resonator impedance matching for shot-noise limited, cavity enhanced amplitude modulated laser absorption spectroscopy.

    Science.gov (United States)

    Chow, Jong H; Littler, Ian C M; Rabeling, David S; McClelland, David E; Gray, Malcolm B

    2008-05-26

    We introduce a closed-loop feedback technique to actively control the coupling condition of an optical cavity, by employing amplitude modulation of the interrogating laser. We show that active impedance matching of the cavity facilitates optimal shot-noise sensing performance in a cavity enhanced system, while its control error signal can be used for intra-cavity absorption or loss signal extraction. We present the first demonstration of this technique with a fiber ring cavity, and achieved shot-noise limited loss sensitivity. We also briefly discuss further use of impedance matching control as a tool for other applications.

  10. Preliminary Results on Different Impedance Contrast Agents for Pulmonary Perfusion Imaging with Electrical Impedance Tomography

    Science.gov (United States)

    Nguyen, D. T.; Kosobrodov, R.; Barry, M. A.; Chik, W.; Pouliopoulos, J.; Oh, T. I.; Thiagalingam, A.; McEwan, A.

    2013-04-01

    Recent studies in animal models suggest that the use of small volume boluses of NaCl as an impedance contrast agent can significantly improve pulmonary perfusion imaging by Electrical Impedance Tomography (EIT). However, these studies used highly concentrated NaCl solution (20%) which may have adverse effects on the patients. In a pilot experiment, we address this problem by comparing a number of different Impedance Contrast Boluses (ICBs). Conductivity changes in the lungs of a sheep after the injection of four different ICBs were compared, including three NaCl-based ICBs and one glucose-based ICB. The following procedure was followed for each ICB. Firstly, ventilation was turned off to provide an apneic window of approximately 40s to image the conductivity changes due to the ICB. Each ICB was then injected through a pig-tail catheter directly into the right atrium. EIT images were acquired throughout the apnea to capture the conductivity change. For each ICB, the experiment was repeated three times. The three NaCl-based ICB exhibited similar behaviour in which following the injection of each of these ICBs, the conductivity of each lung predictably increased. The effect of the ICB of 5% glucose solution was inconclusive. A small decrease in conductivity in the left lung was observed in two out of three cases and none was discernible in the right lung.

  11. Equivalent Circuits For AC-Impedance Analysis Of Corrosion

    Science.gov (United States)

    Danford, M. D.

    1992-01-01

    Report presents investigation of equivalent circuits for ac-impedance analysis of corrosion. Impedance between specimen and electrolyte measured as function of frequency. Data used to characterize corrosion electrochemical system in terms of equivalent circuit. Eleven resistor/capacitor equivalent-circuit models were analyzed.

  12. Equivalent circuit models for ac impedance data analysis

    Science.gov (United States)

    Danford, M. D.

    1990-01-01

    A least-squares fitting routine has been developed for the analysis of ac impedance data. It has been determined that the checking of the derived equations for a particular circuit with a commercially available electronics circuit program is essential. As a result of the investigation described, three equivalent circuit models were selected for use in the analysis of ac impedance data.

  13. Application of dynamic impedance spectroscopy to atomic force microscopy

    Directory of Open Access Journals (Sweden)

    Kazimierz Darowicki, Artur Zieliński and Krzysztof J Kurzydłowski

    2008-01-01

    Full Text Available Atomic force microscopy (AFM is a universal imaging technique, while impedance spectroscopy is a fundamental method of determining the electrical properties of materials. It is useful to combine those techniques to obtain the spatial distribution of an impedance vector. This paper proposes a new combining approach utilizing multifrequency scanning and simultaneous AFM scanning of an investigated surface.

  14. Beam Coupling Impedances of Obstacles Protruding into Beam Pipe

    CERN Document Server

    Kurennoy, S S

    1997-01-01

    The beam coupling impedances of small obstacles protruding inside the vacuum chamber of an accelerator are calculated at frequencies for which the wavelength is large compared to a typical size of the obstacle. Formulas for a few important particular cases are presented which allow simple practical estimates of the broad-band impedance contributions from such discontinuities.

  15. Impedance to transesophageal atrial pacing: significance regarding power sources.

    Science.gov (United States)

    Kerr, C R; Chung, D C; Wickham, G; Jameson, M; Vorderbrugge, S

    1989-06-01

    Transesophageal stimulation is an expeditious method of atrial pacing. Using pulse widths of 10 msec results in reduction of current requirement to values that are usually less than 15 mA. An unknown variable in transesophageal atrial pacing has been impedance. In this study, we investigated the impedance to transesophageal atrial pacing in ten patients using a stimulator with a 63 V power source capable of delivering constant current to 20 mA against an impedance of 2,000 ohms. A bipolar electrode was used to deliver stimuli with a current of 15 mA. Voltage across a known resistance and current were measured on an oscilloscope and the impedance was calculated. Pacing thresholds were also performed and ranged from 6.2 to 16.5 mA (mean 9.4 +/- 2.9 mA, SD). Impedance varied between 720 and 2,670 ohms (mean 1,750 +/- 540 ohms). The stimulator used to measure impedance in man and two other commercially available stimulators were bench tested against known resistances of 500 to 2,000 ohms. The other stimulators with power sources of 12.5 and 15 V had attenuation of the delivered current at resistances of between 1,000 and 2,000 ohms. Thus, this study has demonstrated that transesophageal atrial pacing incurs impedances two to five times greater than incurred with intracardiac pacing leads. Therefore stimulators with high power sources are required to deliver the programmed current against these impedances.

  16. Effect of Feeding and Suction on Gastric Impedance Spectroscopy Measurements.

    Science.gov (United States)

    Beltran, Nohra E; Sánchez-Miranda, Gustavo; Sacristan, Emilio

    2015-01-01

    A specific device and system has been developed and tested for clinical monitoring of gastric mucosal reactance in the critically ill as an early warning of splanchnic hypoperfusion associated with shock and sepsis. This device has been proven effective in clinical trials and is expected to become commercially available next year. The system uses a combination nasogastric tube and impedance spectroscopy probe as a single catheter. Because this device has a double function, the question is: Does enteral feeding or suction affect the gastric reactance measurements? This study was designed to evaluate the effect of feeding and suction on the measurement of gastric impedance spectroscopy in healthy volunteers. Impedance spectra were obtained from the gastric wall epithelia of 18 subjects. The spectra were measured for each of the following conditions: postinsertion of gastric probe, during active suction, postactive suction, and during enteral feeding (236 ml of nutritional supplement). Impedance spectra were reproducible in all volunteers under all conditions tested. There was a slight increase in impedance parameters after suction, and a decrease in impedance after feeding; however, these observed differences were insignificant compared to patient-to-patient variability, and truly negligible compared with previously observed changes associated with splanchnic ischemia in critically ill patients. Our results demonstrate that suction or feeding when using the impedance spectro-metry probe/nasogastric tube does not significantly interfere with gastric impedance spectrometer measurements.

  17. Interpretation of the Gerischer impedance in solid state ionics

    NARCIS (Netherlands)

    Boukamp, Bernard A.; Bouwmeester, Henricus J.M.

    2003-01-01

    The Gerischer impedance in its most elementary form, ZG(ω)=Z0(k+jω)−1/2, has been observed in the frequency response of mixed conducting solid electrolyte systems. This simple transfer function can be derived directly from Fick's second law by including a reaction term. The Gerischer impedance was o

  18. Impedance Analysis of SOGI-FLL-Based Grid Synchronization

    DEFF Research Database (Denmark)

    Yi, Hao; Wang, Xiongfei; Blaabjerg, Frede

    2017-01-01

    The latest research has pointed out that the Phase-Locked Loop (PLL) plays an important role in shaping the impedance of grid-connected converters, yet most of the works so far merely focus on the synchronous reference-frame PLL. Alternatively, this letter presents the impedance analysis of the S...

  19. Impedance Matching of Tapered Slot Antenna using a Dielectric Transformer

    Science.gov (United States)

    Simons, R. N.; Lee, R. Q.

    1998-01-01

    A new impedance matching technique for tapered slot antennas using a dielectric transformer is presented. The technique is demonstrated by measuring the input impedance, Voltage Standing Wave Ratio (VSWR) and the gain of a Vivaldi antenna (VA). Measured results at Ka-Band frequencies are presented and discussed.

  20. Impedance Conjugate Matching of Plasmonic Nanoantenna in Optical Nanocircuits

    DEFF Research Database (Denmark)

    Sachkou, Yauhen; Andryieuski, Andrei; Lavrinenko, Andrei

    2011-01-01

    nanocircuitry to nanoscale optical microscopy and ultra-sensing. The coupling efficiency between nanoantenna and other elements in integrated optical nanocircuit strongly depends on its properties where the impedance matching plays a crucial role. We investigate the dependence of impedance of the T...

  1. Analysis and design of complex impedance transforming marchand baluns

    DEFF Research Database (Denmark)

    Michaelsen, Rasmus Schandorph; Johansen, Tom Keinicke; Tamborg, Kjeld M.

    2014-01-01

    A new type of Marchand balun is presented in this paper, which has the property of complex impedance transformation. To allow the Marchand balun to transform between arbitrary complex impedances, three reactances should be added to the circuit. A detailed analysis of the circuit gives the governi...

  2. Induced optical metric in the non-impedance-matched media

    Science.gov (United States)

    Mousavi, S. A.; Roknizadeh, R.; Sahebdivan, S.

    2016-11-01

    In non-magnetic anisotropic media, the behavior of electromagnetic waves depends on the polarization and direction of the incident light. Therefore, to tame the unwanted wave responses such as polarization dependent reflections, the artificial impedance-matched media are suggested to be used in optical devices like invisibility cloak or super lenses. Nevertheless, developing the impedance-matched media is far from trivial in practice. In this paper, we are comparing the samples of both impedance-matched and non-impedance-matched (non-magnetic) media regarding their electromagnetic response in constructing a well-defined optical metric. In the case of similar anisotropic patterns, we show that the optical metric in an impedance-matched medium for unpolarized light is the same as the optical metric of an electrical birefringent medium when the extraordinary mode is concerned. By comparing the eikonal equation in an empty curved space-time and its counterparts in the medium, we have shown that a non-impedance-matched medium can resemble an optical metric for a particular polarization. As an example of non-impedance-matched materials, we are studying a medium with varying optical axis profile. We show that such a medium can be an alternative to impedance-matched materials in various optical devices.

  3. The Impedance Response of Semiconductors: An Electrochemical Engineering Perspective.

    Science.gov (United States)

    Orazem, Mark E.

    1990-01-01

    Shows that the principles learned in the study of mass transport, thermodynamics, and kinetics associated with electrochemical systems can be applied to the transport and reaction processes taking place within a semiconductor. Describes impedance techniques and provides several graphs illustrating impedance data for diverse circuit systems. (YP)

  4. Electrochemical impedance spectroscopy in solid state ionics: recent advances

    NARCIS (Netherlands)

    Boukamp, Bernard A.

    2004-01-01

    Electrochemical Impedance Spectroscopy (EIS) has become an important research tool in Solid State Ionics. Some new developments are highlighted: new methods of automatic parameter extraction from impedance measurements are briefly discussed. The Kramers–Kronig data validation test presents another p

  5. Development of a field-portable small-size impedance analyzer for structural health monitoring using the electromechanical impedance technique

    Science.gov (United States)

    Giurgiutiu, Victor; Xu, Buli

    2004-07-01

    Electromechanical (E/M) impedance method is emerging as an effective and powerful technique for structural health monitoring. The E/M impedance method utilizes as its main apparatus an impedance analyzer that reads the in-situ E/M impedance of piezoelectric wafer active sensors (PWAS) attached to the monitored structure. Laboratory-type impedance analyzers (e.g. HP4194) are bulky, heavy, and expensive. They cannot be easily carried into the field for on-site structural health monitoring. To address this issue, means of to reduce the size of the impedance analyzer making the impedance analyzer more compact and field-portable are explored. In this paper, we present a systematic approach to the development of a field-portable small-size impedance analyzer for structural health monitoring using the electromechanical impedance technique. Our approach consists of several developmental stages. First, we perform a simulation of the E/M Impedance technique and develop the software tools for analyzing the signal in a fast and efficient way while maintaining the desired accuracy. The objective of this signal processing part is to obtain the complex impedance, ZR+iZI)=|Z| angle arg Z, at a number of frequencies in a predetermined range. Several signal processing methods were explored such as: (a) integration method; (b) correlation method; (c) Discrete Fourier transform (DFT) method. Second, we discuss the hardware issues associated with the implementation of this approach. The hardware system architecture consists of several blocks: (a) reference signal generation; (b) voltage and current measurements; and (c) digital signal acquisition and processing. Practical results obtained during proof-of-concept experiments are presented and comparatively examined.

  6. Modeling and Simulation of Longitudinal Dynamics for Low Energy Ring_High Energy Ring at the Positron-Electron Project

    Energy Technology Data Exchange (ETDEWEB)

    Rivetta, Claudio; Mastorides, T.; Fox, J.D.; Teytelman, D.; Van Winkle, D.; /SLAC

    2007-03-06

    A time domain dynamic modeling and simulation tool for beam-cavity interactions in the Low Energy Ring (LER) and High Energy Ring (HER) at the Positron-Electron Project (PEP-II) is presented. Dynamic simulation results for PEP-II are compared to measurements of the actual machine. The motivation for this tool is to explore the stability margins and performance limits of PEP-II radio-frequency (RF) systems at future higher currents and upgraded RF configurations. It also serves as a test bed for new control algorithms and can define the ultimate limits of the low-level RF (LLRF) architecture. The time domain program captures the dynamic behavior of the beam-cavity-LLRF interaction based on a reduced model. The ring current is represented by macrobunches. Multiple RF stations in the ring are represented via one or two macrocavities. Each macrocavity captures the overall behavior of all the 2 or 4 cavity RF stations. Station models include nonlinear elements in the klystron and signal processing. This enables modeling the principal longitudinal impedance control loops interacting via the longitudinal beam model. The dynamics of the simulation model are validated by comparing the measured growth rates for the LER with simulation results. The simulated behavior of the LER at increased operation currents is presented via low-mode instability growth rates. Different control strategies are compared and the effects of both the imperfections in the LLRF signal processing and the nonlinear drivers and klystrons are explored.

  7. Modeling the Impedance of Nanostructured PV in Simulink/matlab

    Science.gov (United States)

    Houshmand, Mohammad; Zandi, Mohammad. H.; Gorji, Nima E.

    2013-08-01

    Impedance measurement is a common method to study the electrical properties of thin film photovoltaics. For the first time, we use the MATLAB/Simulink environment to extract the complex impedance of the nanostructured heterojunction solar cells. The impedance magnitude, phase and Nyquist plot of the PV are simulated in LTI Viewer and Impedance versus Frequency analysis tools of SimPower GUI block of Simulink. We examined a variety of the equivalent circuits consisting of capacitance, series and shunt resistances representing the solar cell structure. The model uses the parameters with values reported in the literature at room temperature and zero bias. The effect of the additional capacitance and resistances in the equivalent circuits on the impedance components of the cells is considered by Simulink environment.

  8. AC impedance study of degradation of porous nickel battery electrodes

    Science.gov (United States)

    Lenhart, Stephen J.; Macdonald, D. D.; Pound, B. G.

    1987-01-01

    AC impedance spectra of porous nickel battery electrodes were recorded periodically during charge/discharge cycling in concentrated KOH solution at various temperatures. A transmission line model (TLM) was adopted to represent the impedance of the porous electrodes, and various model parameters were adjusted in a curve fitting routine to reproduce the experimental impedances. Degradation processes were deduced from changes in model parameters with electrode cycling time. In developing the TLM, impedance spectra of planar (nonporous) electrodes were used to represent the pore wall and backing plate interfacial impedances. These data were measured over a range of potentials and temperatures, and an equivalent circuit model was adopted to represent the planar electrode data. Cyclic voltammetry was used to study the characteristics of the oxygen evolution reaction on planar nickel electrodes during charging, since oxygen evolution can affect battery electrode charging efficiency and ultimately electrode cycle life if the overpotential for oxygen evolution is sufficiently low.

  9. Method of estimating pulse response using an impedance spectrum

    Energy Technology Data Exchange (ETDEWEB)

    Morrison, John L; Morrison, William H; Christophersen, Jon P; Motloch, Chester G

    2014-10-21

    Electrochemical Impedance Spectrum data are used to predict pulse performance of an energy storage device. The impedance spectrum may be obtained in-situ. A simulation waveform includes a pulse wave with a period greater than or equal to the lowest frequency used in the impedance measurement. Fourier series coefficients of the pulse train can be obtained. The number of harmonic constituents in the Fourier series are selected so as to appropriately resolve the response, but the maximum frequency should be less than or equal to the highest frequency used in the impedance measurement. Using a current pulse as an example, the Fourier coefficients of the pulse are multiplied by the impedance spectrum at corresponding frequencies to obtain Fourier coefficients of the voltage response to the desired pulse. The Fourier coefficients of the response are then summed and reassembled to obtain the overall time domain estimate of the voltage using the Fourier series analysis.

  10. Mechanical impedance of the human body in vertical direction.

    Science.gov (United States)

    Holmlund, P; Lundström, R; Lindberg, L

    2000-08-01

    The mechanical impedance of the human body in sitting posture and vertical direction was measured during different experimental conditions, such as vibration level (0.5-1.4 m/s2), frequency (2-100 Hz), body weight (57-92 kg), relaxed and erect upper body posture. The outcome shows that impedance increases with frequency up to a peak at about 5 Hz after which it decreases in a complex manner which includes two additional peaks. The frequency at which the first and second impedance peak occurs decreases with higher vibration level. Erect, compared with relaxed body posture resulted in higher impedance magnitudes and with peaks located at somewhat higher frequencies. Heavy persons show higher impedance magnitudes and peaks at lower frequencies.

  11. Acoustic impedances of audiometric earphones coupled to different loads

    DEFF Research Database (Denmark)

    Ciric, Dejan; Hammershøi, Dorte

    2005-01-01

    The acoustic impedance of an audiometric earphone is one of the factors that can affect sound transmission through the ear during tests of hearing sensitivity. Similar situation exists during calibration of the earphone where its impedance can affect sound transmission through a coupler...... impedances is applied, which is based on the transfer function between two microphone locations in an impedance tube. For that purpose, the special measuring tube containing four microphones is developed, where different pairs of microphones are used for different frequency ranges. During the measurements......, audiometric earphones are coupled to different loads. Thus, they are placed on different terminations of the tube including metal plate, artificial rubber pinna and upper part of the standardized coupler. The results show that the impedances of earphones are different, but they also differ from radiation...

  12. [Effects of different electrodes on bioelectrical impedance values].

    Science.gov (United States)

    Nakadomo, F; Tanaka, K; Yokoyama, T; Maeda, K

    1990-01-01

    Effects of different electrodes on bioelectrical impedance values measured by the Selco bioelectrical impedance plethysmograph (SIF-881, Japan) were investigated using 8 adult females (age: 35.3 +/- 7.6 yr, Ht: 156.9 +/- 3.8 cm, Wt: 57.1 +/- 9.9 kg, and hydrodensitometrically determined body fat: 29.4 +/- 6.0%). The Lectec MP3000 electrode (Liberty Carton, USA) and the Bipolar electrode (Sanwa, Japan) produced significantly higher impedance values when compared to the Disposable electrode (Adovance, Japan) and the ECG electrode (Nihon Kohden, Japan). The coefficient of variation was significantly lower for the Disposable electrode (0.8%) and the ECG electrode (0.2%) than that for the Lectec MP3000 electrode (2.3%) and the Bipolar electrode (4.9%). In conclusion, the ECG electrode provides higher bioelectrical impedance values with the highest reproducibility in the assessment of human body composition by the bioelectrical impedance plethysmography.

  13. Longitudinal Impedance Measurements of the Components for the BEPCII

    CERN Document Server

    Zhou, Demin; Kang, Wen; Wang Jiu Qing; Zhou, Lijuan

    2005-01-01

    A longitudinal impedance measurement system was established for the BEPCII. The measurements, done in the frequency domain, are based on the coaxial wire method using HP/Agilent 8720ES network analyzer. The applications of the TRL calibration technique and absorbers were investigated to find a good approach for impedance measurements. The impedance, larger than 20 Ohm and below 6 GHz, can be measured using the TRL calibration technique in the experiment. And better measurement results were got using the reference pipes with the absorbers. So, this system satisfies the requirements of the BEPCII. This paper gives a review on this impedance measurements system for the BEPCII. The measurements results show that there are no serious impedance problems for BEPCII bellows and injection kickers, agreeing well with the numerical simulations. More improvements on this system are in progress.

  14. A Multisection Broadband Impedance Transforming Branch-Line Hybrid

    CERN Document Server

    Kumar, S; Danshin, T

    1995-01-01

    Measurements and design equations for a two section impedance transforming hybrid suitable for MMIC applications and a new method of synthesis for multisection branch-line hybrids are reported. The synthesis method allows the response to be specified either of Butterworth or Chebyshev type. Both symmetric (with equal input and output impedances) and non-symmetric (impedance transforming) designs are feasible. Starting from a given number of sections, type of response, and impedance transformation ratio and for a specified midband coupling, power division ratio, isolation or directivity ripple bandwidth, the set of constants needed for the evaluation of the reflection coefficient response is first calculated. The latter is used to define a driving point impedance of the circuit, synthesize it and obtain the branch line immittances with the use of the concept of double length unit elements (DLUE). The experimental results obtained with microstrip hybrids constructed to test the validity of the brute force optim...

  15. Optical approximation in the theory of geometric impedance

    CERN Document Server

    Stupakov, G; Zagorodnov, I

    2007-01-01

    In this paper we introduce an optical approximation into the theory of impedance calculation, one valid in the limit of high frequencies. This approximation neglects diffraction effects in the radiation process, and is conceptually equivalent to the approximation of geometric optics in electromagnetic theory. Using this approximation, we derive equations for the longitudinal impedance for arbitrary offsets, with respect to a reference orbit, of source and test particles. With the help of the Panofsky-Wenzel theorem we also obtain expressions for the transverse impedance (also for arbitrary offsets). We further simplify these expressions for the case of the small offsets that are typical for practical applications. Our final expressions for the impedance, in the general case, involve two dimensional integrals over various cross-sections of the transition. We further demonstrate, for several known axisymmetric examples, how our method is applied to the calculation of impedances. Finally, we discuss the accuracy...

  16. Plasmonic-Based Electrochemical Impedance Spectroscopy: Application to Molecular Binding

    Science.gov (United States)

    Lu, Jin; Wang, Wei; Wang, Shaopeng; Shan, Xiaonan; Li, Jinghong; Tao, Nongjian

    2012-01-01

    Plasmonic-based electrochemical impedance spectroscopy (P-EIS) is developed to investigate molecular binding on surfaces. Its basic principle relies on the sensitive dependence of surface plasmon resonance (SPR) signal on surface charge density, which is modulated by applying an AC potential to a SPR chip surface. The AC component of the SPR response gives the electrochemical impedance, and the DC component provides the conventional SPR detection. The plasmonic-based impedance measured over a range of frequency is in quantitative agreement with the conventional electrochemical impedance. Compared to the conventional SPR detection, P-EIS is sensitive to molecular binding taking place on the chip surface, and less sensitive to bulk refractive index changes or non-specific binding. Moreover, this new approach allows for simultaneous SPR and surface impedance analysis of molecular binding processes. PMID:22122514

  17. Optimal Workloop Energetics of Muscle-Actuated Systems: An Impedance Matching View

    Science.gov (United States)

    Farahat, Waleed A.; Herr, Hugh M.

    2010-01-01

    Integrative approaches to studying the coupled dynamics of skeletal muscles with their loads while under neural control have focused largely on questions pertaining to the postural and dynamical stability of animals and humans. Prior studies have focused on how the central nervous system actively modulates muscle mechanical impedance to generate and stabilize motion and posture. However, the question of whether muscle impedance properties can be neurally modulated to create favorable mechanical energetics, particularly in the context of periodic tasks, remains open. Through muscle stiffness tuning, we hypothesize that a pair of antagonist muscles acting against a common load may produce significantly more power synergistically than individually when impedance matching conditions are met between muscle and load. Since neurally modulated muscle stiffness contributes to the coupled muscle-load stiffness, we further anticipate that power-optimal oscillation frequencies will occur at frequencies greater than the natural frequency of the load. These hypotheses were evaluated computationally by applying optimal control methods to a bilinear muscle model, and also evaluated through in vitro measurements on frog Plantaris longus muscles acting individually and in pairs upon a mass-spring-damper load. We find a 7-fold increase in mechanical power when antagonist muscles act synergistically compared to individually at a frequency higher than the load natural frequency. These observed behaviors are interpreted in the context of resonance tuning and the engineering notion of impedance matching. These findings suggest that the central nervous system can adopt strategies to harness inherent muscle impedance in relation to external loads to attain favorable mechanical energetics. PMID:20532203

  18. Optimal workloop energetics of muscle-actuated systems: an impedance matching view.

    Directory of Open Access Journals (Sweden)

    Waleed A Farahat

    2010-06-01

    Full Text Available Integrative approaches to studying the coupled dynamics of skeletal muscles with their loads while under neural control have focused largely on questions pertaining to the postural and dynamical stability of animals and humans. Prior studies have focused on how the central nervous system actively modulates muscle mechanical impedance to generate and stabilize motion and posture. However, the question of whether muscle impedance properties can be neurally modulated to create favorable mechanical energetics, particularly in the context of periodic tasks, remains open. Through muscle stiffness tuning, we hypothesize that a pair of antagonist muscles acting against a common load may produce significantly more power synergistically than individually when impedance matching conditions are met between muscle and load. Since neurally modulated muscle stiffness contributes to the coupled muscle-load stiffness, we further anticipate that power-optimal oscillation frequencies will occur at frequencies greater than the natural frequency of the load. These hypotheses were evaluated computationally by applying optimal control methods to a bilinear muscle model, and also evaluated through in vitro measurements on frog Plantaris longus muscles acting individually and in pairs upon a mass-spring-damper load. We find a 7-fold increase in mechanical power when antagonist muscles act synergistically compared to individually at a frequency higher than the load natural frequency. These observed behaviors are interpreted in the context of resonance tuning and the engineering notion of impedance matching. These findings suggest that the central nervous system can adopt strategies to harness inherent muscle impedance in relation to external loads to attain favorable mechanical energetics.

  19. Optimal workloop energetics of muscle-actuated systems: an impedance matching view.

    Science.gov (United States)

    Farahat, Waleed A; Herr, Hugh M

    2010-06-03

    Integrative approaches to studying the coupled dynamics of skeletal muscles with their loads while under neural control have focused largely on questions pertaining to the postural and dynamical stability of animals and humans. Prior studies have focused on how the central nervous system actively modulates muscle mechanical impedance to generate and stabilize motion and posture. However, the question of whether muscle impedance properties can be neurally modulated to create favorable mechanical energetics, particularly in the context of periodic tasks, remains open. Through muscle stiffness tuning, we hypothesize that a pair of antagonist muscles acting against a common load may produce significantly more power synergistically than individually when impedance matching conditions are met between muscle and load. Since neurally modulated muscle stiffness contributes to the coupled muscle-load stiffness, we further anticipate that power-optimal oscillation frequencies will occur at frequencies greater than the natural frequency of the load. These hypotheses were evaluated computationally by applying optimal control methods to a bilinear muscle model, and also evaluated through in vitro measurements on frog Plantaris longus muscles acting individually and in pairs upon a mass-spring-damper load. We find a 7-fold increase in mechanical power when antagonist muscles act synergistically compared to individually at a frequency higher than the load natural frequency. These observed behaviors are interpreted in the context of resonance tuning and the engineering notion of impedance matching. These findings suggest that the central nervous system can adopt strategies to harness inherent muscle impedance in relation to external loads to attain favorable mechanical energetics.

  20. Simulations and measurements of coupling impedance for modern particle accelerator devices

    CERN Document Server

    AUTHOR|(CDS)2158523; Biancacci, Nicolò; Mostacci, Andrea

    In this document it has been treated the study of the coupling impedance in modern devices, already installed or not, in different particle accelerators. In the specific case: • For a device in-phase of project, several simulations for impedance calculation have been done. • For a component already realized and used, measurements of coupling impedance value have been done. Simulations are used to determine the impact of the interconnect between to magnets, designed for the future particle accelerator FCC, on the overall impedance of the machine which is about 100 km long. In particular has been done a check between theory, simulations and measurements of components already built, allowing a better and deeper study of the component we have analysed. Controls that probably will be helpful to have a clear guideline in future works. The measurements instead concern in an existing component that was already used in LHC, the longest particle accelerator ever realised on the planet, 27 km long. The coupling impe...