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Sample records for eddy current sensors

  1. Design and optimization of a flexible arrayed eddy current sensor

    Science.gov (United States)

    Sun, Zhenguo; Cai, Dong; Zou, Cheng; Zhang, Wenzeng; Chen, Qiang

    2017-04-01

    The inspection of the hollow axle inner surfaces is a key process to guarantee the safety of high-speed trains. A novel flexible arrayed eddy current sensor was developed to improve the reliability of the non-destructive testing of the hollow axle inner surfaces, whose main innovative aspect was the new design of excitation/sensing traces to achieve a differential and arrayed configuration. Only two independent excitation traces were used in the sensor to induce eddy currents, which can be detected by 16 differential sensing elements. The lift-off effects and the influence of the excitation frequency and geometrical parameters of the proposed sensor was investigated and presented in this paper. Finite element models were built to analyze the effects of each parameter on the sensor response amplitude. Experimental validations were conducted using a representative set of sensors. Results from experiments and simulations were consistent with each other, which showed that the sensor design can substantially suppress the lift-off effects and modifications of the studied parameters can substantially improve the sensor performance.

  2. Optimization design of the coil of the eddy current sensor

    Science.gov (United States)

    Pu, Tiecheng; Fan, Shangchun

    2006-11-01

    An eddy current sensor is usually used to measure the departure of a shaft from its axes, in order to avoid destroying the system because of collision. The design of the coil as the sense organ of an eddy current sensor is to search a set of proper sizes (includes the outer radius, the inner radius and tallness of the coil) in which the quality factor and the grads of magnetic field strength is great as soon as possible but the length of the lead is not much long. So an optimization function is introduced here for efficient design. This function is direct ratio with the quality factor of the core and the magnetic grads product by the coil and inverse ratio with the lead length. The proportions of three parameters can be changed according to the instance. When the value of the function reaches the maximum, the sizes of coil are the anticipant optimal sizes and the integration capability of the coil is at the high-point. To search the maximum of the function, the genetic algorithm is adopted. The simulation result by Matlab proves the practicability of the method.

  3. An ink-jet printed eddy current position sensor.

    Science.gov (United States)

    Jeranče, Nikola; Bednar, Nikola; Stojanović, Goran

    2013-04-18

    An eddy current sensor with an ink-jet printed flexible inductor has been designed and fabricated. The inductor has been designed by means of software developed in-house. It has been fabricated by ink-jet printing with silver ink on a flexible substrate. The inductor is a part of the oscillator circuit whose oscillating frequency is measured by a microcontroller. The sensor characteristics have been analyzed for two types of application. The first considered application is the displacement of a large conductive target in a direction perpendicular to the inductor plane. The second considered application is the displacement of a small steel ball parallel to the inductor plane. Inductance and oscillating frequency have been measured in order to completely characterize the sensor. The obtained results validate the use of the sensor for both considered applications, and are in good agreement with the simulations. The advantages of this type of sensor are low cost, the possibility for the inductor to match any curved surface and flexibility and precision of the inductor design.

  4. An Ink-Jet Printed Eddy Current Position Sensor

    Directory of Open Access Journals (Sweden)

    Goran Stojanović

    2013-04-01

    Full Text Available An eddy current sensor with an ink-jet printed flexible inductor has been designed and fabricated. The inductor has been designed by means of software developed in-house. It has been fabricated by ink-jet printing with silver ink on a flexible substrate. The inductor is a part of the oscillator circuit whose oscillating frequency is measured by a microcontroller. The sensor characteristics have been analyzed for two types of application. The first considered application is the displacement of a large conductive target in a direction perpendicular to the inductor plane. The second considered application is the displacement of a small steel ball parallel to the inductor plane. Inductance and oscillating frequency have been measured in order to completely characterize the sensor. The obtained results validate the use of the sensor for both considered applications, and are in good agreement with the simulations. The advantages of this type of sensor are low cost, the possibility for the inductor to match any curved surface and flexibility and precision of the inductor design.

  5. High Temperature, Through the Case Eddy Current Sensor for Blade Vibration Measurements Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Preliminary results have shown that low temperature eddy current sensors can provide excellent resolution for blade tip timing, and have the ability to see ?through...

  6. A Novel Forging Hammerhead Displacement Detection System Based on Eddy Current Sensor

    National Research Council Canada - National Science Library

    Chun-Long Zhang; Zi-Guo Chen

    2014-01-01

      For strong vibration, high temperature and dust in the forging site, a displacement detection system based on eddy current sensor is proposed to monitor the size of forgings online in this paper...

  7. A Smart Eddy Current Sensor Dedicated to the Nondestructive Evaluation of Carbon Fibers Reinforced Polymers.

    Science.gov (United States)

    Naidjate, Mohammed; Helifa, Bachir; Feliachi, Mouloud; Lefkaier, Iben-Khaldoun; Heuer, Henning; Schulze, Martin

    2017-08-31

    This paper propose a new concept of an eddy current (EC) multi-element sensor for the characterization of carbon fiber-reinforced polymers (CFRP) to evaluate the orientations of plies in CFRP and the order of their stacking. The main advantage of the new sensors is the flexible parametrization by electronical switching that reduces the effort for mechanical manipulation. The sensor response was calculated and proved by 3D finite element (FE) modeling. This sensor is dedicated to nondestructive testing (NDT) and can be an alternative for conventional mechanical rotating and rectangular sensors.

  8. A Steel Ball Surface Quality Inspection Method Based on a Circumferential Eddy Current Array Sensor

    Directory of Open Access Journals (Sweden)

    Huayu Zhang

    2017-07-01

    Full Text Available To efficiently inspect surface defects on steel ball bearings, a new method based on a circumferential eddy current array (CECA sensor was proposed here. The best probe configuration, in terms of the coil quality factor (Q-factor, magnetic field intensity, and induced eddy current density on the surface of a sample steel ball, was determined using 3-, 4-, 5-, and 6-coil probes, for analysis and comparison. The optimal lift-off from the measured steel ball, the number of probe coils, and the frequency of excitation current suitable for steel ball inspection were obtained. Using the resulting CECA sensor to inspect 46,126 steel balls showed a miss rate of ~0.02%. The sensor was inspected for surface defects as small as 0.05 mm in width and 0.1 mm in depth.

  9. Fatigue Crack Length Sizing Using a Novel Flexible Eddy Current Sensor Array

    Directory of Open Access Journals (Sweden)

    Ruifang Xie

    2015-12-01

    Full Text Available The eddy current probe, which is flexible, array typed, highly sensitive and capable of quantitative inspection is one practical requirement in nondestructive testing and also a research hotspot. A novel flexible planar eddy current sensor array for the inspection of microcrack presentation in critical parts of airplanes is developed in this paper. Both exciting and sensing coils are etched on polyimide films using a flexible printed circuit board technique, thus conforming the sensor to complex geometric structures. In order to serve the needs of condition-based maintenance (CBM, the proposed sensor array is comprised of 64 elements. Its spatial resolution is only 0.8 mm, and it is not only sensitive to shallow microcracks, but also capable of sizing the length of fatigue cracks. The details and advantages of our sensor design are introduced. The working principal and the crack responses are analyzed by finite element simulation, with which a crack length sizing algorithm is proposed. Experiments based on standard specimens are implemented to verify the validity of our simulation and the efficiency of the crack length sizing algorithm. Experimental results show that the sensor array is sensitive to microcracks, and is capable of crack length sizing with an accuracy within ±0.2 mm.

  10. Precise on-machine extraction of the surface normal vector using an eddy current sensor array

    Science.gov (United States)

    Wang, Yongqing; Lian, Meng; Liu, Haibo; Ying, Yangwei; Sheng, Xianjun

    2016-11-01

    To satisfy the requirements of on-machine measurement of the surface normal during complex surface manufacturing, a highly robust normal vector extraction method using an Eddy current (EC) displacement sensor array is developed, the output of which is almost unaffected by surface brightness, machining coolant and environmental noise. A precise normal vector extraction model based on a triangular-distributed EC sensor array is first established. Calibration of the effects of object surface inclination and coupling interference on measurement results, and the relative position of EC sensors, is involved. A novel apparatus employing three EC sensors and a force transducer was designed, which can be easily integrated into the computer numerical control (CNC) machine tool spindle and/or robot terminal execution. Finally, to test the validity and practicability of the proposed method, typical experiments were conducted with specified testing pieces using the developed approach and system, such as an inclined plane and cylindrical and spherical surfaces.

  11. A Flexible Arrayed Eddy Current Sensor for Inspection of Hollow Axle Inner Surfaces

    Directory of Open Access Journals (Sweden)

    Zhenguo Sun

    2016-06-01

    Full Text Available A reliable and accurate inspection of the hollow axle inner surface is important for the safe operation of high-speed trains. In order to improve the reliability of the inspection, a flexible arrayed eddy current sensor for non-destructive testing of the hollow axle inner surface was designed, fabricated and characterized. The sensor, consisting of two excitation traces and 28 sensing traces, was developed by using the flexible printed circuit board (FPCB technique to conform the geometric features of the inner surfaces of the hollow axles. The main innovative aspect of the sensor was the new arrangement of excitation/sensing traces to achieve a differential configuration. Finite element model was established to analyze sensor responses and to determine the optimal excitation frequency. Experimental validations were conducted on a specimen with several artificial defects. Results from experiments and simulations were consistent with each other, with the maximum relative error less than 4%. Both results proved that the sensor was capable of detecting longitudinal and transverse defects with the depth of 0.5 mm under the optimal excitation frequency of 0.9 MHz.

  12. Standard practice for characterization of coatings using conformable Eddy-Current sensors without coating reference standards

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    1.1 This practice covers the use of conformable eddy-current sensors for nondestructive characterization of coatings without standardization on coated reference parts. It includes the following: (1) thickness measurement of a conductive coating on a conductive substrate, (2) detection and characterization of local regions of increased porosity of a conductive coating, and (3) measurement of thickness for nonconductive coatings on a conductive substrate or on a conductive coating. This practice includes only nonmagnetic coatings on either magnetic (μ ≠ μ0) or nonmagnetic (μ = μ0) substrates. This practice can also be used to measure the effective thickness of a process-affected zone (for example, shot peened layer for aluminum alloys, alpha case for titanium alloys). For specific types of coated parts, the user may need a more specific procedure tailored to a specific application.

  13. Analysis of temperature influence on the informative parameters of single-coil eddy current sensors

    Science.gov (United States)

    Borovik, S. Yu.; Kuteynikova, M. M.; Sekisov, Yu. N.; Skobelev, O. P.

    2017-07-01

    This paper describes the study of temperature in the flowing part of a turbine on the informative parameters (equivalent inductances of primary windings of matching transformers) of single-coil eddy-current sensors with a sensitive element in the form of a conductor section, which are used as part of automation systems for testing gas-turbine engines. In this case, the objects of temperature influences are both sensors and controlled turbine blades. The existing model of electromagnetic interaction of a sensitive element with the end part of a controlled blade is used to obtain quantitative estimates of temperature changes of equivalent inductances of sensitive elements and primary windings of matching transformers. This model is also used to determine the corresponding changes of the informative parameter of the sensor in the process of experimental studies of temperature influences on it (in the absence of blades in the sensitive region). This paper also presents transformations in the form of relationships of informative parameters with radial and axial displacements at normal (20 °C) and nominal (1000 °C) temperatures, and their difference is used to determine the families of dominant functions of temperature, which characterize possible temperature errors for any radial and axial displacements in the ranges of their variation.

  14. Eddy current testing

    Energy Technology Data Exchange (ETDEWEB)

    Song, Sung Jin; Lee, Hyang Beom; Kim, Young Hwan [Soongsil Univ., Seoul (Korea, Republic of); Shin, Young Kil [Kunsan Univ., Gunsan (Korea, Republic of)

    2004-02-15

    Eddy current testing has been widely used for non destructive testing of steam generator tubes. In order to retain reliability in ECT, the following subjects were carried out in this study: numerical modeling and analysis of defects by using BC and RPC probes in SG tube, preparation of absolute coil impedance plane diagram by FEM. Signal interpretation of the eddy current signals obtained from nuclear power plants.

  15. Eddy current sensor for in-situ monitoring of swelling of Li-ion prismatic cells

    Energy Technology Data Exchange (ETDEWEB)

    Plotnikov, Yuri, E-mail: plotnikov@ge.com; Karp, Jason, E-mail: plotnikov@ge.com; Knobloch, Aaron, E-mail: plotnikov@ge.com; Kapusta, Chris, E-mail: plotnikov@ge.com; Lin, David, E-mail: plotnikov@ge.com [GE Global Research, One Research Circle, Niskayuna, NY (United States)

    2015-03-31

    In-situ monitoring an on-board rechargeable battery in hybrid cars can be used to ensure a long operating life of the battery and safe operation of the vehicle. Intercalations of ions in the electrode material during charge and discharge of a Lithium Ion battery cause periodic stress and strain of the electrode materials that can ultimately lead to fatigue resulting in capacity loss and potential battery failure. Currently this process is not monitored directly on the cells. This work is focused on development technologies that would quantify battery swelling and provide in-situ monitoring for onboard vehicle applications. Several rounds of tests have been performed to spatially characterize cell expansion of a 5 Ah cell with a nickel/manganese/cobalt-oxide cathode (Sanyo, Japan) used by Ford in their Fusion HEV battery pack. A collaborative team of researchers from GE and the University of Michigan has characterized the free expansion of these cells to be in the range of 100×125 microns (1% of total cell thickness) at the center point of the cell. GE proposed to use a thin eddy current (EC) coil to monitor these expansions on the cells while inside the package. The photolithography manufacturing process previously developed for EC arrays for detecting cracks in aircraft engine components was used to build test coils for gap monitoring. These sensors are thin enough to be placed safely between neighboring cells and capable of monitoring small variations in the gap between the cells. Preliminary investigations showed that these coils can be less than 100 micron thick and have sufficient sensitivity in a range from 0 to 2 mm. Laboratory tests revealed good correlation between EC and optical gap measurements in the desired range. Further technology development could lead to establishing a sensor network for a low cost solution for the in-situ monitoring of cell swelling during battery operation.

  16. Development of High Resolution Eddy Current Imaging Using an Electro-Mechanical Sensor (Preprint)

    Science.gov (United States)

    2011-11-01

    magnetic force microscope [MFM] to generate and detect eddy currents. A magnetic tip cantilever of a MFM equipped with a piezoelectric element was...displacements with a laser vibrometer . Displacement was estimated to be at 8.2 nm in magnitude. These values were plugged into equation (1) assuming

  17. Micromagnetics with eddy currents

    Energy Technology Data Exchange (ETDEWEB)

    Iyer, R; Millhollon, J; Long, K, E-mail: ram.iyer@ttu.edu [Room 201, Department of Mathematics and Statistics, Texas Tech University, Lubbock, TX 79409 (United States)

    2011-01-01

    In this paper, we study the modified Landau-Lifshitz-Gilbert (LLG) equation for of a conducting, magnetic body. The modified LLG equations include the magnetic field due to eddy currents in the total effective magnetic field. We derive an expression for the magnetic field due to eddy current losses and show that it is well defined. We then show that the work done by the eddy currents in opposing the change of magnetization is a Rayleigh type dissipation function, and derive the modified LLG equations using the calculus of variations. Finally, we show that the modified LLG equations lead to a decrease in the Gibbs energy. This implies that the LLG equations describes a dynamic process proceeding spontaneously forward in time.

  18. Unsupervised Classification of Surface Defects in Wire Rod Production Obtained by Eddy Current Sensors

    Directory of Open Access Journals (Sweden)

    Sergio Saludes-Rodil

    2015-04-01

    Full Text Available An unsupervised approach to classify surface defects in wire rod manufacturing is developed in this paper. The defects are extracted from an eddy current signal and classified using a clustering technique that uses the dynamic time warping distance as the dissimilarity measure. The new approach has been successfully tested using industrial data. It is shown that it outperforms other classification alternatives, such as the modified Fourier descriptors.

  19. Eddy current sensing of intermetallic composite consolidation

    Science.gov (United States)

    Dharmasena, Kumar P.; Wadley, Haydn N. G.

    1991-01-01

    A finite element method is used to explore the feasibility and optimization of a probe-type eddy current sensor for determining the thickness of plate specimens during a hot isostatic pressing cycle. The dependence of the sensor's impedance upon sample-sensor separation in the high frequency limit is calculated, and factors that maximize sensitivity to the final stages of densification are identified.

  20. A Novel High Sensitivity Sensor for Remote Field Eddy Current Non-Destructive Testing Based on Orthogonal Magnetic Field

    Directory of Open Access Journals (Sweden)

    Xiaojie Xu

    2014-12-01

    Full Text Available Remote field eddy current is an effective non-destructive testing method for ferromagnetic tubular structures. In view of conventional sensors’ disadvantages such as low signal-to-noise ratio and poor sensitivity to axial cracks, a novel high sensitivity sensor based on orthogonal magnetic field excitation is proposed. Firstly, through a three-dimensional finite element simulation, the remote field effect under orthogonal magnetic field excitation is determined, and an appropriate configuration which can generate an orthogonal magnetic field for a tubular structure is developed. Secondly, optimized selection of key parameters such as frequency, exciting currents and shielding modes is analyzed in detail, and different types of pick-up coils, including a new self-differential mode pick-up coil, are designed and analyzed. Lastly, the proposed sensor is verified experimentally by various types of defects manufactured on a section of a ferromagnetic tube. Experimental results show that the proposed novel sensor can largely improve the sensitivity of defect detection, especially for axial crack whose depth is less than 40% wall thickness, which are very difficult to detect and identify by conventional sensors. Another noteworthy advantage of the proposed sensor is that it has almost equal sensitivity to various types of defects, when a self-differential mode pick-up coil is adopted.

  1. Eddy current probe development based on a magnetic sensor array; Developpement d'un imageur magnetique pour le controle non destructif par courants de Foucault

    Energy Technology Data Exchange (ETDEWEB)

    Vacher, F

    2007-06-15

    This research deals with in the study of the use of innovating magnetic sensors in eddy current non destructive inspection. The author reports an analysis survey of magnetic sensor performances. This survey enables the selection of magnetic sensor technologies used in non destructive inspection. He presents the state-of-the-art of eddy current probes exploiting the qualities of innovating magnetic sensors, and describes the methods enabling the use of these magnetic sensors in non destructive testing. Two main applications of innovating magnetic sensors are identified: the detection of very small defects by means of magneto-resistive sensors, and the detection of deep defects by means of giant magneto-impedances. Based on the use of modelling, optimization, signal processing tools, probes are manufactured for these both applications.

  2. Conformable eddy current array delivery

    Science.gov (United States)

    Summan, Rahul; Pierce, Gareth; Macleod, Charles; Mineo, Carmelo; Riise, Jonathan; Morozov, Maxim; Dobie, Gordon; Bolton, Gary; Raude, Angélique; Dalpé, Colombe; Braumann, Johannes

    2016-02-01

    The external surface of stainless steel containers used for the interim storage of nuclear material may be subject to Atmospherically Induced Stress Corrosion Cracking (AISCC). The inspection of such containers poses a significant challenge due to the large quantities involved; therefore, automating the inspection process is of considerable interest. This paper reports upon a proof-of-concept project concerning the automated NDT of a set of test containers containing artificially generated AISCCs. An Eddy current array probe with a conformable padded surface from Eddyfi was used as the NDT sensor and end effector on a KUKA KR5 arc HW robot. A kinematically valid cylindrical raster scan path was designed using the KUKA|PRC path planning software. Custom software was then written to interface measurement acquisition from the Eddyfi hardware with the motion control of the robot. Preliminary results and analysis are presented from scanning two canisters.

  3. Eddy Current Testing with Giant Magnetoresistance (GMR) Sensors and a Pipe-Encircling Excitation for Evaluation of Corrosion under Insulation.

    Science.gov (United States)

    Bailey, Joseph; Long, Nicholas; Hunze, Arvid

    2017-09-28

    This work investigates an eddy current-based non-destructive testing (NDT) method to characterize corrosion of pipes under thermal insulation, one of the leading failure mechanisms for insulated pipe infrastructure. Artificial defects were machined into the pipe surface to simulate the effect of corrosion wall loss. We show that by using a giant magnetoresistance (GMR) sensor array and a high current (300 A), single sinusoidal low frequency (5-200 Hz) pipe-encircling excitation scheme it is possible to quantify wall loss defects without removing the insulation or weather shield. An analysis of the magnetic field distribution and induced currents was undertaken using the finite element method (FEM) and analytical calculations. Simple algorithms to remove spurious measured field variations not associated with defects were developed and applied. The influence of an aluminium weather shield with discontinuities and dents was ascertained and found to be small for excitation frequency values below 40 Hz. The signal dependence on the defect dimensions was analysed in detail. The excitation frequency at which the maximum field amplitude change occurred increased linearly with the depth of the defect by about 3 Hz/mm defect depth. The change in magnetic field amplitude due to defects for sensors aligned in the azimuthal and radial directions were measured and found to be linearly dependent on the defect volume between 4400-30,800 mm³ with 1.2 × 10-3-1.6 × 10-3 µT/mm³. The results show that our approach is well suited for measuring wall loss defects similar to the defects from corrosion under insulation.

  4. Tool vibration detection with eddy current sensors in machining process and computation of stability lobes using fuzzy classifiers

    Science.gov (United States)

    Devillez, Arnaud; Dudzinski, Daniel

    2007-01-01

    Today the knowledge of a process is very important for engineers to find optimal combination of control parameters warranting productivity, quality and functioning without defects and failures. In our laboratory, we carry out research in the field of high speed machining with modelling, simulation and experimental approaches. The aim of our investigation is to develop a software allowing the cutting conditions optimisation to limit the number of predictive tests, and the process monitoring to prevent any trouble during machining operations. This software is based on models and experimental data sets which constitute the knowledge of the process. In this paper, we deal with the problem of vibrations occurring during a machining operation. These vibrations may cause some failures and defects to the process, like workpiece surface alteration and rapid tool wear. To measure on line the tool micro-movements, we equipped a lathe with a specific instrumentation using eddy current sensors. Obtained signals were correlated with surface finish and a signal processing algorithm was used to determine if a test is stable or unstable. Then, a fuzzy classification method was proposed to classify the tests in a space defined by the width of cut and the cutting speed. Finally, it was shown that the fuzzy classification takes into account of the measurements incertitude to compute the stability limit or stability lobes of the process.

  5. Remote field eddy current testing

    Energy Technology Data Exchange (ETDEWEB)

    Cheong, Y. M.; Jung, H. K.; Huh, H.; Lee, Y. S.; Shim, C. M

    2001-03-01

    The state-of-art technology of the remote field eddy current, which is actively developed as an electromagnetic non-destructive testing tool for ferromagnetic tubes, is described. The historical background and recent R and D activities of remote-field eddy current technology are explained including the theoretical development of remote field eddy current, such as analytical and numerical approach, and the results of finite element analysis. The influencing factors for actual applications, such as the effect of frequency, magnetic permeability, receiving sensitivity, and difficulties of detection and classification of defects are also described. Finally, two examples of actual application, 1) the gap measurement between pressure tubes and calandria tube in CANDU reactor and, 2) the detection of defects in the ferromagnetic heat exchanger tubes, are described. The future research efforts are also included.

  6. Eddy sensors for small diameter stainless steel tubes.

    Energy Technology Data Exchange (ETDEWEB)

    Skinner, Jack L.; Morales, Alfredo Martin; Grant, J. Brian; Korellis, Henry James; LaFord, Marianne Elizabeth; Van Blarigan, Benjamin; Andersen, Lisa E.

    2011-08-01

    The goal of this project was to develop non-destructive, minimally disruptive eddy sensors to inspect small diameter stainless steel metal tubes. Modifications to Sandia's Emphasis/EIGER code allowed for the modeling of eddy current bobbin sensors near or around 1/8-inch outer diameter stainless steel tubing. Modeling results indicated that an eddy sensor based on a single axial coil could effectively detect changes in the inner diameter of a stainless steel tubing. Based on the modeling results, sensor coils capable of detecting small changes in the inner diameter of a stainless steel tube were designed, built and tested. The observed sensor response agreed with the results of the modeling and with eddy sensor theory. A separate limited distribution SAND report is being issued demonstrating the application of this sensor.

  7. A method and sensor for the eddy current non destructive testing of thin tubes; Procede de controle non destructif d`un tube mince par courants de Foucault

    Energy Technology Data Exchange (ETDEWEB)

    Sartre, B.; Miller, D.; Placko, D.

    1995-06-02

    In order to control the wear (cracking or thinning) of vapor generator tubes, especially in PWR reactors, due to the friction between the tubes and dampers, an eddy current control system is proposed where the transducer is run through the tubes, and measures the tube wall thickness or tube-block clearance through impedance measurements, taking into account the variation of the sensor-to-tube distance. 8 fig.

  8. Detection and Inspection of Steel Bars in Reinforced Concrete Structures Using Active Infrared Thermography with Microwave Excitation and Eddy Current Sensors.

    Science.gov (United States)

    Szymanik, Barbara; Frankowski, Paweł Karol; Chady, Tomasz; John Chelliah, Cyril Robinson Azariah

    2016-02-16

    The purpose of this paper is to present a multi-sensor approach to the detection and inspection of steel bars in reinforced concrete structures. In connection with our past experience related to non-destructive testing of different materials, we propose using two potentially effective methods: active infrared thermography with microwave excitation and the eddy current technique. In this article active infrared thermography with microwave excitation is analyzed both by numerical modeling and experiments. This method, based on thermal imaging, due to its characteriatics should be considered as a preliminary method for the assessment of relatively shallowly located steel bar reinforcements. The eddy current technique, on the other hand, allows for more detailed evaluation and detection of deeply located rebars. In this paper a series of measurement results, together with the initial identification of certain features of steel reinforcement bars will be presented.

  9. Detection and Inspection of Steel Bars in Reinforced Concrete Structures Using Active Infrared Thermography with Microwave Excitation and Eddy Current Sensors

    Directory of Open Access Journals (Sweden)

    Barbara Szymanik

    2016-02-01

    Full Text Available The purpose of this paper is to present a multi-sensor approach to the detection and inspection of steel bars in reinforced concrete structures. In connection with our past experience related to non-destructive testing of different materials, we propose using two potentially effective methods: active infrared thermography with microwave excitation and the eddy current technique. In this article active infrared thermography with microwave excitation is analyzed both by numerical modeling and experiments. This method, based on thermal imaging, due to its characteriatics should be considered as a preliminary method for the assessment of relatively shallowly located steel bar reinforcements. The eddy current technique, on the other hand, allows for more detailed evaluation and detection of deeply located rebars. In this paper a series of measurement results, together with the initial identification of certain features of steel reinforcement bars will be presented.

  10. Rotating concave eddy current probe

    Science.gov (United States)

    Roach, Dennis P [Albuquerque, NM; Walkington, Phil [Albuquerque, NM; Rackow, Kirk A [Albuquerque, NM; Hohman, Ed [Albuquerque, NM

    2008-04-01

    A rotating concave eddy current probe for detecting fatigue cracks hidden from view underneath the head of a raised head fastener, such as a buttonhead-type rivet, used to join together structural skins, such as aluminum aircraft skins. The probe has a recessed concave dimple in its bottom surface that closely conforms to the shape of the raised head. The concave dimple holds the probe in good alignment on top of the rivet while the probe is rotated around the rivet's centerline. One or more magnetic coils are rigidly embedded within the probe's cylindrical body, which is made of a non-conducting material. This design overcomes the inspection impediment associated with widely varying conductivity in fastened joints.

  11. Development of Meandering Winding Magnetometer (MWM (Register Trademark)) Eddy Current Sensors for the Health Monitoring, Modeling and Damage Detection of High Temperature Composite Materials

    Science.gov (United States)

    Russell, Richard; Washabaugh, Andy; Sheiretov, Yanko; Martin, Christopher; Goldfine, Neil

    2011-01-01

    The increased use of high-temperature composite materials in modern and next generation aircraft and spacecraft have led to the need for improved nondestructive evaluation and health monitoring techniques. Such technologies are desirable to improve quality control, damage detection, stress evaluation and temperature measurement capabilities. Novel eddy current sensors and sensor arrays, such as Meandering Winding Magnetometers (MWMs) have provided alternate or complimentary techniques to ultrasound and thermography for both nondestructive evaluation (NDE) and structural health monitoring (SHM). This includes imaging of composite material quality, damage detection and .the monitoring of fiber temperatures and multidirectional stresses. Historically, implementation of MWM technology for the inspection of the Space Shuttle Orbiter Reinforced Carbon-Carbon Composite (RCC) leading edge panels was developed by JENTEK Sensors and was subsequently transitioned by NASA as an operational pre and post flight in-situ inspection at the Kennedy Space Center. A manual scanner, which conformed'automatically to the curvature of the RCC panels was developed and used as a secondary technique if a defect was found during an infrared thermography screening, During a recent proof of concept study on composite overwrapped pressure vessels (COPV's), three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed excellent correlation with actual surface strain gage measurements. Recent advancements of this technology have been made applying MWM sensor technology for scanning COPVs for mechanical damage. This presentation will outline the recent advance in the MWM.technology and the development of MWM techniques for NDE and SHM of carbon wraped composite overwrapped pressure vessels (COPVs) including the measurement of internal stresses via a surface mounted sensor

  12. Non-Destructive Techniques Based on Eddy Current Testing

    Directory of Open Access Journals (Sweden)

    Ernesto Vázquez-Sánchez

    2011-02-01

    Full Text Available Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future.

  13. Non-Destructive Techniques Based on Eddy Current Testing

    Science.gov (United States)

    García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto

    2011-01-01

    Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future. PMID:22163754

  14. Non-destructive techniques based on eddy current testing.

    Science.gov (United States)

    García-Martín, Javier; Gómez-Gil, Jaime; Vázquez-Sánchez, Ernesto

    2011-01-01

    Non-destructive techniques are used widely in the metal industry in order to control the quality of materials. Eddy current testing is one of the most extensively used non-destructive techniques for inspecting electrically conductive materials at very high speeds that does not require any contact between the test piece and the sensor. This paper includes an overview of the fundamentals and main variables of eddy current testing. It also describes the state-of-the-art sensors and modern techniques such as multi-frequency and pulsed systems. Recent advances in complex models towards solving crack-sensor interaction, developments in instrumentation due to advances in electronic devices, and the evolution of data processing suggest that eddy current testing systems will be increasingly used in the future.

  15. Observed eddy dissipation in the Agulhas Current

    CSIR Research Space (South Africa)

    Braby, L

    2016-08-01

    Full Text Available Channel and south of Madagascar dissipate as they approach the Agulhas Current. By tracking the offshore position of the current core and its velocity at 30°S in relation to eddies, it is demonstrated that eddy dissipation occurs through a transfer...

  16. Eddy Current Probe for Surface and Sub-Surface Inspection

    Science.gov (United States)

    Wincheski, Russell A. (Inventor); Simpson, John W. (Inventor)

    2014-01-01

    An eddy current probe includes an excitation coil for coupling to a low-frequency alternating current (AC) source. A magneto-resistive sensor is centrally disposed within and at one end of the excitation coil to thereby define a sensing end of the probe. A tubular flux-focusing lens is disposed between the excitation coil and the magneto-resistive sensor. An excitation wire is spaced apart from the magneto-resistive sensor in a plane that is perpendicular to the sensor's axis of sensitivity and such that, when the sensing end of the eddy current probe is positioned adjacent to the surface of a structure, the excitation wire is disposed between the magneto-resistive sensor and the surface of the structure. The excitation wire is coupled to a high-frequency AC source. The excitation coil and flux-focusing lens can be omitted when only surface inspection is required.

  17. Continued Development of Meandering Winding Magnetometer (MWM (Register Trademark)) Eddy Current Sensors for the Health Monitoring, Modeling and Damage Detection of Composite Overwrapped Pressure Vessels

    Science.gov (United States)

    Russell, Richard; Wincheski, Russell; Jablonski, David; Washabaugh, Andy; Sheiretov, Yanko; Martin, Christopher; Goldfine, Neil

    2011-01-01

    Composite Overwrapped Pressure Vessels (COPVs) are used in essentially all NASA spacecraft, launch. vehicles and payloads to contain high-pressure fluids for propulsion, life support systems and science experiments. Failure of any COPV either in flight or during ground processing would result in catastrophic damage to the spacecraft or payload, and could lead to loss of life. Therefore, NASA continues to investigate new methods to non-destructively inspect (NDE) COPVs for structural anomalies and to provide a means for in-situ structural health monitoring (SHM) during operational service. Partnering with JENTEK Sensors, engineers at NASA, Kennedy Space Center have successfully conducted a proof-of-concept study to develop Meandering Winding Magnetometer (MWM) eddy current sensors designed to make direct measurements of the stresses of the internal layers of a carbon fiber composite wrapped COPV. During this study three different MWM sensors were tested at three orientations to demonstrate the ability of the technology to measure stresses at various fiber orientations and depths. These results showed good correlation with actual surface strain gage measurements. MWM-Array technology for scanning COPVs can reliably be used to image and detect mechanical damage. To validate this conclusion, several COPVs were scanned to obtain a baseline, and then each COPV was impacted at varying energy levels and then rescanned. The baseline subtracted images were used to demonstrate damage detection. These scans were performed with two different MWM-Arrays. with different geometries for near-surface and deeper penetration imaging at multiple frequencies and in multiple orientations of the linear MWM drive. This presentation will include a review of micromechanical models that relate measured sensor responses to composite material constituent properties, validated by the proof of concept study, as the basis for SHM and NDE data analysis as well as potential improvements including

  18. Eddy Current Model of Ball Lightning

    OpenAIRE

    Shelton, J. D.

    2011-01-01

    Eddy Current Model of Ball Lightning Calculations show that high-energy ball lightning may consist of a ball of plasma containing a large circular electric current arising as an eddy current generated by lightning. Synthetic ball lightning might serve as a method of plasma confinement for purposes of nuclear fusion. In this paper, three articles concerning ball lightning and the related phenomenon of large ball lightning are combined to provide insight into this rarely glimpsed occurrence.

  19. Process Specification for Eddy Current Inspection

    Science.gov (United States)

    Koshti, Ajay

    2011-01-01

    This process specification establishes the minimum requirements for eddy current inspection of flat surfaces, fastener holes, threaded fasteners and seamless and welded tubular products made from nonmagnetic alloys such as aluminum and stainless steel.

  20. A western boundary current eddy characterisation study

    Science.gov (United States)

    Ribbe, Joachim; Brieva, Daniel

    2016-12-01

    The analysis of an eddy census for the East Australian Current (EAC) region yielded a total of 497 individual short-lived (7-28 days) cyclonic and anticyclonic eddies for the period 1993 to 2015. This was an average of about 23 eddies per year. 41% of the tracked individual cyclonic and anticyclonic eddies were detected off southeast Queensland between about 25 °S and 29 °S. This is the region where the flow of the EAC intensifies forming a swift western boundary current that impinges near Fraser Island on the continental shelf. This zone was also identified as having a maximum in detected short-lived cyclonic eddies. A total of 94 (43%) individual cyclonic eddies or about 4-5 per year were tracked in this region. The census found that these potentially displaced entrained water by about 115 km with an average displacement speed of about 4 km per day. Cyclonic eddies were likely to contribute to establishing an on-shelf longshore northerly flow forming the western branch of the Fraser Island Gyre and possibly presented an important cross-shelf transport process in the life cycle of temperate fish species of the EAC domain. In-situ observations near western boundary currents previously documented the entrainment, off-shelf transport and export of near shore water, nutrients, sediments, fish larvae and the renewal of inner shelf water due to short-lived eddies. This study found that these cyclonic eddies potentially play an important off-shelf transport process off the central east Australian coast.

  1. Eddy Current Rail Inspection Using AC Bridge Techniques.

    Science.gov (United States)

    Liu, Ze; Koffman, Andrew D; Waltrip, Bryan C; Wang, Yicheng

    2013-01-01

    AC bridge techniques commonly used for precision impedance measurements have been adapted to develop an eddy current sensor for rail defect detection. By using two detection coils instead of just one as in a conventional sensor, we can balance out the large baseline signals corresponding to a normal rail. We have significantly enhanced the detection sensitivity of the eddy current method by detecting and demodulating the differential signal of the two coils induced by rail defects, using a digital lock-in amplifier algorithm. We have also explored compensating for the lift-off effect of the eddy current sensor due to vibrations by using the summing signal of the detection coils to measure the lift-off distance. The dominant component of the summing signal is a constant resulting from direct coupling from the excitation coil, which can be experimentally determined. The remainder of the summing signal, which decreases as the lift-off distance increases, is induced by the secondary eddy current. This dependence on the lift-off distance is used to calibrate the differential signal, allowing for a more accurate characterization of the defects. Simulated experiments on a sample rail have been performed using a computer controlled X-Y moving table with the X-axis mimicking the train's motion and the Y-axis mimicking the train's vibrational bumping. Experimental results demonstrate the effectiveness of the new detection method.

  2. Eddy Current Testing, RQA/M1-5330.17.

    Science.gov (United States)

    National Aeronautics and Space Administration, Huntsville, AL. George C. Marshall Space Flight Center.

    As one in the series of classroom training handbooks, prepared by the U.S. space program, instructional material is presented in this volume concerning familiarization and orientation on eddy current testing. The subject is presented under the following headings: Introduction, Eddy Current Principles, Eddy Current Equipment, Eddy Current Methods,…

  3. Wind changes above warm Agulhas Current eddies

    CSIR Research Space (South Africa)

    Roualt, M

    2016-10-01

    Full Text Available Sea-surface temperature (SST), altimetry derived sea-level anomalies (SLA) and surface current are used south of the Agulhas Current to identify warm core mesoscale ocean eddies presenting a distinct SST perturbation superior to 1(supo...

  4. About Eddy Currents in Induction Melting Processes

    Directory of Open Access Journals (Sweden)

    Gafiţa Nicolae-Bogdan

    2008-05-01

    Full Text Available In this paper we present a method forcomputing the eddy currents in induction meltingprocesses for non-ferrous alloys. We take intoconsideration the situation when only the crucible ismoving, inside the coils. This fact makes differentialcomputation methods to be hard to apply, because isnecessary to generate a new mesh and a new systemmatrix for every for every new position of the cruciblerelated to the coils. Integral methods cancel thisdrawback because the mesh is generated only for thedomains with eddy currents. For integral methods, themesh and the inductance matrix remain unchangedduring the movement of the crucible; only the free termsof the equation system will change.

  5. Health Monitoring of Composite Overwrapped Pressure Vessels (COPVs) Using Meandering Winding Magnetometer ((MWM(Registered Trademark)) Eddy Current Sensors

    Science.gov (United States)

    Russell, Rick; Grundy, David; Jablonski, David; Martin, Christopher; Washabaugh, Andrew; Goldfine, Neil

    2011-01-01

    There are 3 mechanisms that affect the life of a COPV are: a) The age life of the overwrap; b) Cyclic fatigue of the metallic liner; c) Stress Rupture life. The first two mechanisms are understood through test and analysis. A COPV Stress Rupture is a sudden and catastrophic failure of the overwrap while holding at a stress level below the ultimate strength for an extended time. Currently there is no simple, deterministic method of determining the stress rupture life of a COPV, nor a screening technique to determine if a particular COPV is close to the time of a stress rupture failure. Conclusions: Demonstrated a correlation between MWM response and pressure or strain. Demonstrated the ability to monitor stress in COPV at different orientations and depths. FA41 provides best correlation with bottle pressure or stress.

  6. Eddy current signal comparison for tube identification

    Science.gov (United States)

    Glass, S. W.; Vojvodic, R.

    2015-03-01

    Inspection of nuclear power plant steam generator tubes is required to justify continued safe plant operation. The steam generators consist of thousands of tubes with nominal diameters of 15 to 22mm, approximately 1mm wall thickness, and 20 to 30m in length. The tubes are inspected by passing an eddy current probe through the tubes from tube end to tube end. It is critical to know exactly which tube identification (row and column) is associated with each tube's data. This is controlled by a precision manipulator that provides the tube ID to the eddy current system. Historically there have been some instances where the manipulator incorrectly reported the tube ID. This can have serious consequences including lack of inspection of a tube, or if a pluggable indication is detected, the tube is likely to be mis-plugged thereby risking a primary to secondary leak.

  7. Eddy current inspection tool. [Patent application

    Science.gov (United States)

    Petrini, R.R.; Van Lue, D.F.

    1980-10-29

    A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment with a probe coil, and associated coaxial coil cable, oil energizing means, and circuit means responsive to impedance changes in the coil as effected by induced eddy currents in a test object to produce a data output signal proportional to such changes. The coil and cable are slideably received in the utility channel of the flexible insertion tube of a fiberoptic scope. The scope is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means for articulating the distal end of the tube and permitting close control of coil placement relative to a test object. The eddy current sensing equipment includes a tone generator for generating audible signals responsive to the data output signal. In one selected mode of operation, the tone generator responsive to the output signal above a selected level generates a constant single frequency tone for signalling detection of a discontinuity and, in a second selected mode, generates a tone whose frequency is proportional to the difference between the output signal and a predetermined selected threshold level.

  8. Defect Characterization Based on Eddy Current Technique: Technical Review

    Directory of Open Access Journals (Sweden)

    Ruzlaini Ghoni

    2014-08-01

    Full Text Available Eddy current testing is widely used for nondestructive evaluation of metallic structures in characterizing numerous types of defects occurring in various locations. It offers remarkable advantages over other nondestructive techniques because of its ease of implementation. This paper presents a technical review of Eddy current technique in various scope of defect detection. The first part presents Eddy current evaluation on various defects location and orientation such as steam generator tubes, stress crack corrosion, and fatigue cracks. The next section analyzes the use of pulsed Eddy current and pulsed Eddy current thermography as an alternative method for monitoring the growth of cracks with the aid of computational techniques for postsignal analysis.

  9. IVA Ultrasonic and Eddy Current NDE for ISS Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Phased array ultrasonic testing (PAUT) instruments and array eddy current testing instruments were tested on hypervelocity impact damaged aluminum plates simulating...

  10. Eddy-current-damped microelectromechanical switch

    Energy Technology Data Exchange (ETDEWEB)

    Christenson, Todd R. (Albuquerque, NM); Polosky, Marc A. (Tijeras, NM)

    2007-10-30

    A microelectromechanical (MEM) device is disclosed that includes a shuttle suspended for movement above a substrate. A plurality of permanent magnets in the shuttle of the MEM device interact with a metal plate which forms the substrate or a metal portion thereof to provide an eddy-current damping of the shuttle, thereby making the shuttle responsive to changes in acceleration or velocity of the MEM device. Alternately, the permanent magnets can be located in the substrate, and the metal portion can form the shuttle. An electrical switch closure in the MEM device can occur in response to a predetermined acceleration-time event. The MEM device, which can be fabricated either by micromachining or LIGA, can be used for sensing an acceleration or deceleration event (e.g. in automotive applications such as airbag deployment or seat belt retraction).

  11. Eddy-current-damped microelectromechanical switch

    Energy Technology Data Exchange (ETDEWEB)

    Christenson, Todd R [Albuquerque, NM; Polosky, Marc A [Tijeras, NM

    2009-12-15

    A microelectromechanical (MEM) device is disclosed that includes a shuttle suspended for movement above a substrate. A plurality of permanent magnets in the shuttle of the MEM device interact with a metal plate which forms the substrate or a metal portion thereof to provide an eddy-current damping of the shuttle, thereby making the shuttle responsive to changes in acceleration or velocity of the MEM device. Alternately, the permanent magnets can be located in the substrate, and the metal portion can form the shuttle. An electrical switch closure in the MEM device can occur in response to a predetermined acceleration-time event. The MEM device, which can be fabricated either by micromachining or LIGA, can be used for sensing an acceleration or deceleration event (e.g. in automotive applications such as airbag deployment or seat belt retraction).

  12. Material Nondestructive Evalution by Eddy Current Testing Material Nondestructive Evalution by Eddy Current Testing

    Directory of Open Access Journals (Sweden)

    Tomas Marek

    2005-01-01

    Full Text Available Eddy current method is one of many methods of nondestructive testing. The aim of nondestructive testing is prevention of equipment breakdown without any impact on equipment operation. Especially breakdowns coused by hidden material defect from witch is equipment or part of equipment made. This paper explains the basic principles of method and present its functionality by simulation.
    Eddy current method is one of many methods of nondestructive testing. The aim of nondestructive testing is prevention of equipment breakdown without any impact on equipment operation. Especially breakdowns coused by hidden material defect from witch is equipment or part of equipment made. This paper explains the basic principles of method and present its functionality by simulation.

  13. Wind changes above warm Agulhas Current eddies

    CSIR Research Space (South Africa)

    Rouault, M

    2016-01-01

    Full Text Available speeds above the eddies at the instantaneous scale; 20 % of cases had incomplete data due to partial global coverage by the scatterometer for one path. For cases where the wind is stronger above warm eddies, there is no relationship between the increase...

  14. Pulsed Eddy Current Sensing for Critical Pipe Condition Assessment.

    Science.gov (United States)

    Ulapane, Nalika; Alempijevic, Alen; Vidal Calleja, Teresa; Valls Miro, Jaime

    2017-09-26

    Pulsed Eddy Current (PEC) sensing is used for Non-Destructive Evaluation (NDE) of the structural integrity of metallic structures in the aircraft, railway, oil and gas sectors. Urban water utilities also have extensive large ferromagnetic structures in the form of critical pressure pipe systems made of grey cast iron, ductile cast iron and mild steel. The associated material properties render NDE of these pipes by means of electromagnetic sensing a necessity. In recent years PEC sensing has established itself as a state-of-the-art NDE technique in the critical water pipe sector. This paper presents advancements to PEC inspection in view of the specific information demanded from water utilities along with the challenges encountered in this sector. Operating principles of the sensor architecture suitable for application on critical pipes are presented with the associated sensor design and calibration strategy. A Gaussian process-based approach is applied to model a functional relationship between a PEC signal feature and critical pipe wall thickness. A case study demonstrates the sensor's behaviour on a grey cast iron pipe and discusses the implications of the observed results and challenges relating to this application.

  15. Variation of Eddy Current Density Distribution and its Effect on Crack Signal in Eddy Current Non-Destructive of Testing

    Directory of Open Access Journals (Sweden)

    Ladislav Janousek

    2006-01-01

    Full Text Available The paper deals with variation of eddy current density distribution along material depth and investigates an effect of the variation on a crack signal in eddy current non-destructive testing. Four coaxial rectangular tangential coils are used to induce eddy currents in a tested conductive object. The exciting coils are driven independently by phase-shifted AC currents; a ratio of amplitudes of the exciting currents is continuously changed to vary the distribution of eddy current density along material depth under a circular pick-up coil positioned in centre between the exciting coils. Dependences of a crack signal amplitude and its phase on the ratio are evaluated and special features are extracted. It is revealed that the dependences are strongly influenced by depth of a crack, and thus the extracted features can enhance evaluation of a detected crack.

  16. Resolution of effects in multi-frequency eddy current data for reliable diagnostics of conductive materials

    DEFF Research Database (Denmark)

    Egorov, Alexander; Kucheryavskiy, Sergey V.; Polyakov, Viktor

    2017-01-01

    and a margin between a sample and a measurement sensor. If both are unknown, it is not possible to evaluate them. The present paper thoroughly reports on an attempt to resolve the influence of the two factors by applying chemometric methods to the eddy current measurements obtained for a set of frequencies....

  17. Detection of milled 100Cr6 steel surface by eddy current and incremental permeance methods

    Czech Academy of Sciences Publication Activity Database

    Perevertov, Oleksiy; Neslušan, M.; Stupakov, Alexandr

    2017-01-01

    Roč. 87, Apr (2017), s. 15-23 ISSN 0963-8695 R&D Projects: GA ČR GB14-36566G; GA ČR GA13-18993S Institutional support: RVO:68378271 Keywords : Eddy currents * hard milling * incremental permeance * magnetic materials * surface characterization Subject RIV: JB - Sensors, Measurment, Regulation Impact factor: 2.726, year: 2016

  18. System for evaluating weld quality using eddy currents

    Energy Technology Data Exchange (ETDEWEB)

    Todorov, Evgueni I.; Hay, Jacob

    2017-12-12

    Electromagnetic and eddy current techniques for fast automated real-time and near real-time inspection and monitoring systems for high production rate joining processes. An eddy current system, array and method for the fast examination of welds to detect anomalies such as missed seam (MS) and lack of penetration (LOP) the system, array and methods capable of detecting and sizing surface and slightly subsurface flaws at various orientations in connection with at least the first and second weld pass.

  19. Wind Forced Variability in Eddy Formation, Eddy Shedding, and the Separation of the East Australian Current

    Science.gov (United States)

    Bull, Christopher Y. S.; Kiss, Andrew E.; Jourdain, Nicolas C.; England, Matthew H.; van Sebille, Erik

    2017-12-01

    The East Australian Current (EAC), like many other subtropical western boundary currents, is believed to be penetrating further poleward in recent decades. Previous observational and model studies have used steady state dynamics to relate changes in the westerly winds to changes in the separation behavior of the EAC. As yet, little work has been undertaken on the impact of forcing variability on the EAC and Tasman Sea circulation. Here using an eddy-permitting regional ocean model, we present a suite of simulations forced by the same time-mean fields, but with different atmospheric and remote ocean variability. These eddy-permitting results demonstrate the nonlinear response of the EAC to variable, nonstationary inhomogeneous forcing. These simulations show an EAC with high intrinsic variability and stochastic eddy shedding. We show that wind stress variability on time scales shorter than 56 days leads to increases in eddy shedding rates and southward eddy propagation, producing an increased transport and southward reach of the mean EAC extension. We adopt an energetics framework that shows the EAC extension changes to be coincident with an increase in offshore, upstream eddy variance (via increased barotropic instability) and increase in subsurface mean kinetic energy along the length of the EAC. The response of EAC separation to regional variable wind stress has important implications for both past and future climate change studies.

  20. An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design.

    Science.gov (United States)

    Rifai, Damhuji; Abdalla, Ahmed N; Razali, Ramdan; Ali, Kharudin; Faraj, Moneer A

    2017-03-13

    The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient.

  1. Development of eddy current testing system for inspection of combustion chambers of liquid rocket engines.

    Science.gov (United States)

    He, D F; Zhang, Y Z; Shiwa, M; Moriya, S

    2013-01-01

    An eddy current testing (ECT) system using a high sensitive anisotropic magnetoresistive (AMR) sensor was developed. In this system, a 20 turn circular coil with a diameter of 3 mm was used to produce the excitation field. A high sensitivity AMR sensor was used to measure the magnetic field produced by the induced eddy currents. A specimen made of copper alloy was prepared to simulate the combustion chamber of liquid rocket. Scanning was realized by rotating the chamber with a motor. To reduce the influence of liftoff variance during scanning, a dual frequency excitation method was used. The experimental results proved that ECT system with an AMR sensor could be used to check liquid rocket combustion chamber.

  2. Investigation on a new inducer of pulsed eddy current thermography

    Directory of Open Access Journals (Sweden)

    Min He

    2016-09-01

    Full Text Available In this paper, a new inducer of pulsed eddy current thermography (PECT is presented. The use of the inducer can help avoid the problem of blocking the infrared (IR camera’s view in eddy current thermography technique. The inducer can also provide even heating of the test specimen. This paper is concerned with the temperature distribution law around the crack on a specimen when utilizing the new inducer. Firstly, relative mathematical models are provided. In the following section, eddy current distribution and temperature distribution around the crack are studied using the numerical simulation method. The best separation distance between the inducer and the specimen is also determined. Then, results of temperature distribution around the crack stimulated by the inducer are gained by experiments. Effect of current value on temperature rise is studied as well in the experiments. Based on temperature data, temperature features of the crack are discussed.

  3. Sizing Performance of the Newly Developed Eddy Current System

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Chan Hee; Lee, Hee Jong; Yoo, Hyun Ju; Moon, Gyoon Young; Lee, Tae Hoon [Korea Hydro and Nuclear Power Co., Ltd., Daejeon (Korea, Republic of)

    2013-10-15

    This paper describes the comparison results of sizing performance for two systems. The KHNP developed a new eddy current testing system for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment of the newly developed system with the EPRI-qualified system was already carried out. In this paper, the comparisons of depth-sizing performance for the artificial flaws between two systems were performed. The results show that the newly developed system is in good agreement with the qualified system. Therefore, it is expected that the newly developed eddy current system can be used for the inspection of steam generator tubing in nuclear power plants. There are some non-destructive examination (NDE) methods for the inspection of components in nuclear power plants, such as ultrasonic, radiographic, eddy current testing, etc. The eddy current testing is widely used for the inspection of steam generator (SG) tubing because it offers a relatively low cost approach for high speed, large scale testing of metallic materials in high pressure and temperature engineering systems. The Korea Hydro and Nuclear Power Co., Ltd. (KHNP) developed an eddy current testing system for the inspection of steam generator tubing in nuclear power plants. This system includes not only hardware but software such as the frequency generator and data acquisition-analysis program. The foreign eddy current system developed by ZETEC is currently used for the inspection of steam generator tubing in domestic nuclear power plants. The equivalency assessment between two systems was already carried out in accordance with the EPRI steam generator examination guidelines.

  4. Defect detection in conducting materials using eddy current testing techniques

    Directory of Open Access Journals (Sweden)

    Brauer Hartmut

    2014-01-01

    Full Text Available Lorentz force eddy current testing (LET is a novel nondestructive testing technique which can be applied preferably to the identification of internal defects in nonmagnetic moving conductors. The LET is compared (similar testing conditions with the classical eddy current testing (ECT. Numerical FEM simulations have been performed to analyze the measurements as well as the identification of internal defects in nonmagnetic conductors. The results are compared with measurements to test the feasibility of defect identification. Finally, the use of LET measurements to estimate of the electrical conductors under test are described as well.

  5. Superminiature Eddy-current Transducers for Thickness Studies

    Science.gov (United States)

    Sagalakov, A. M.; Dmitriev, S. F.; Malikov, V. N.

    2017-11-01

    On the basis of the transformer type eddy-current transducer we created a measuring system which allows us to estimate the possibility of the eddy-current method application to measure the thickness of the conductive and dielectric coatings placed on the conductive base. We described the structure of the measuring system and the measurement procedure. A scheme that uses a computer as a generator and receiver of signals from windings is proposed. The article contains the data demonstrating the dependency of the amplitude part of the signal on the objects of different thickness and states the objects’ experimentally determined limits of the size that precondition the practicability of these measurements.

  6. Eddies

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The maximum potential area of eddy bars (MPAEB) represents the cumulative area of the eddy occupied by sand at different times within the photographic record...

  7. Eddy current compensated double diffusion encoded (DDE) MRI.

    Science.gov (United States)

    Mueller, Lars; Wetscherek, Andreas; Kuder, Tristan Anselm; Laun, Frederik Bernd

    2017-01-01

    Eddy currents might lead to image distortions in diffusion-weighted echo planar imaging. A method is proposed to reduce their effects on double diffusion encoding (DDE) MRI experiments and the thereby derived microscopic fractional anisotropy (μFA). The twice-refocused spin echo scheme was adapted for DDE measurements. To assess the effect of individual diffusion encodings on the image distortions, measurements of a grid of plastic rods in water were performed. The effect of eddy current compensation on μFA measurements was evaluated in the brains of six healthy volunteers. The use of an eddy current compensation reduced the signal variation. As expected, the distortions caused by the second encoding were larger than those of the first encoding, entailing a stronger need to compensate for them. For an optimal result, however, both encodings had to be compensated. The artifact reduction strongly improved the measurement of the μFA in ventricles and gray matter by reducing the overestimation. An effect of the compensation on absolute μFA values in white matter was not observed. It is advisable to compensate both encodings in DDE measurements for eddy currents. Magn Reson Med 77:328-335, 2017. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  8. International Physics Olympiad'98-Eddy Currents, Flux Linkages

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 5; Issue 5. International Physics Olympiad '98 - Eddy Currents, Flux Linkages. Saikat Guha. Classroom Volume 5 Issue 5 May 2000 pp ... Author Affiliations. Saikat Guha1. Room no. 367, Hall-2, Indian Institute of Technology, Kanpur, UP 208 016, India.

  9. Eddy current testing with high penetration; WS-Pruefungen mit grosser Eindringtiefe

    Energy Technology Data Exchange (ETDEWEB)

    Becker, R.; Kroening, M. [Fraunhofer Inst. fuer Zerstoerungsfreie Pruefverfahren, Saarbruecken (Germany)

    1999-08-01

    The low-frequency eddy current testing method is used when penetration into very deep layers is required. The achievable penetration depth is determined among other parameters by the lowest testing frequency that can be realised together with the eddy current sensor. When using inductive sensors, the measuring effect declines proportional to the lowering frequency (induction effect). Further reduction of testing frequency requires other types of sensors, as e.g. the GMR (Giant Magnetic Resistance), which achieves a constant measuring sensitivity down to the steady field. The multi-frequency eddy current testing method MFEC 3 of IZFP described here can be operated using three different scanning frequencies at a time. Two variants of eddy current probes are used in this case. Both have an inductive winding at their emitters, of the type of a measuring probe. The receiver end is either also an inductive winding, or a magnetic field-responsive resistance (GMR). (orig./CB) [Deutsch] Das Niederfrequenz(NF)-Wirbelstrom(WS)-Verfahren wird eingesetzt, um eine grosse Eindringtiefe zu erzielen. Die erreichbare Tiefenreichweite wird u.a. durch die niedrigste Prueffrequenz bestimmt, die zusammen mit dem Wirbelstrom-Sensor realisiert werden kann. Bei Einsatz von induktiven Sensoren geht mit abnehmender Prueffrequenz der Messeffekt proportional zurueck (Induktionswirkung). Eine weitere Absenkung der Prueffrequenzen macht den Einsatz von andersartigen Sensoren notwendig, z.B. den GMR (Giant Magnetic Resistance), der eine gleichmaessige Messempfindlichkeit bis zum Gleichfeld besitzt. Das eingesetzte Mehrfrequenz-Wirbelstrom-Pruefverfahren MFEC 3 des IZFP arbeitet mit drei gleichzeitig eingespeisten Prueffrequenzen. Dabei werden zwei Varianten von WS-Sensoren eingesetzt. Beide besitzen auf der Senderseite eine induktive Wicklung in der Art einer Tastsonde. Die Empfaengerseite ist entweder ebenfalls eine induktive Wicklung oder ein magnetfeldempfindlicher Widerstand (GMR). (orig./DGE)

  10. Application of special waveform signals for eddy current testing of materials

    Science.gov (United States)

    Polyakov, V. V.; Gracheva, Ya. J.; Egorov, A. V.; Lependin, A. A.

    2017-12-01

    This paper presents an approach for multifrequency eddy current testing based on special waveform excitation signals. Digital processing of received signals provides data for experimental hodographs of a "sensor - testing sample" system. Hodographs for the testing of samples of aluminum materials with an applied dielectric layer demonstrates the reliability of the proposed approach. The application of principal component analysis improves the identification and differentiation of testing parameters. The obtained results can be used in systems for nondestructive testing of metallic materials and products.

  11. Eddy Surface properties and propagation at Southern Hemisphere western boundary current systems

    Science.gov (United States)

    Pilo, G. S.; Mata, M. M.; Azevedo, J. L. L.

    2015-02-01

    Oceanic eddies occur in all world oceans, but are more energetic when associated to western boundary currents (WBC) systems. In these regions, eddies play an important role on mixing and energy exchange. Therefore, it is important to quantify and qualify eddies occurring within these systems. Previous studies performed eddy censuses in Southern Hemisphere WBC systems. However, important aspects of local eddy population are still unknown. Main questions to be answered relate to eddies' spatial distribution, propagation and lifetime within each system. Here, we use a global eddy dataset to qualify eddies based on their surface characteristics at the Agulhas Current (AC), the Brazil Current (BC) and the East Australian Current (EAC) Systems. We show that eddy propagation within each system is highly forced by the local mean flow and bathymetry. In the AC System, eddy polarity dictates its propagation distance. BC system eddies do not propagate beyond the Argentine Basin, and are advected by the local ocean circulation. EAC System eddies from both polarities cross south of Tasmania, but only anticyclonics reach the Great Australian Bight. Eddies in all systems and from both polarities presented a geographical segregation according to size. Large eddies occur along the Agulhas Retroflection, the Agulhas Return Current, the Brazil-Malvinas Confluence and the Coral Sea. Small eddies occur in the systems southernmost domains. Understanding eddies' propagation helps to establish monitoring programs, and to better understand how these features would affect local mixing.

  12. Determining Confounding Sensitivities In Eddy Current Thin Film Measurements

    Energy Technology Data Exchange (ETDEWEB)

    Gros, Ethan; Udpa, Lalita; Smith, James A.; Wachs, Katelyn

    2016-07-01

    Determining Confounding Sensitivities In Eddy Current Thin Film Measurements Ethan Gros, Lalita Udpa, Electrical Engineering, Michigan State University, East Lansing MI 48824 James A. Smith, Experiment Analysis, Idaho National Laboratory, Idaho Falls ID 83415 Eddy current (EC) techniques are widely used in industry to measure the thickness of non-conductive films on a metal substrate. This is done using a system whereby a coil carrying a high-frequency alternating current is used to create an alternating magnetic field at the surface of the instrument's probe. When the probe is brought near a conductive surface, the alternating magnetic field will induce ECs in the conductor. The substrate characteristics and the distance of the probe from the substrate (the coating thickness) affect the magnitude of the ECs. The induced currents load the probe coil affecting the terminal impedance of the coil. The measured probe impedance is related to the lift off between coil and conductor as well as conductivity of the test sample. For a known conductivity sample, the probe impedance can be converted into an equivalent film thickness value. The EC measurement can be confounded by a number of measurement parameters. It is the goal of this research to determine which physical properties of the measurement set-up and sample can adversely affect the thickness measurement. The eddy current testing is performed using a commercially available, hand held eddy current probe (ETA3.3H spring loaded eddy probe running at 8 MHz) that comes with a stand to hold the probe. The stand holds the probe and adjusts the probe on the z-axis to help position the probe in the correct area as well as make precise measurements. The signal from the probe is sent to a hand held readout, where the results are recorded directly in terms of liftoff or film thickness. Understanding the effect of certain factors on the measurements of film thickness, will help to evaluate how accurate the ETA3.3H spring

  13. Practical Application of Eddy Currents Generated by Wind

    Energy Technology Data Exchange (ETDEWEB)

    Dirba, I; Kleperis, J, E-mail: imants.dirba@gmail.com [Institute of Solid State Physics of University of Latvia, 8 Kengaraga Street, Riga, LV-1063 (Latvia)

    2011-06-23

    When a conductive material is subjected to time-varying magnetic fluxes, eddy (Foucault) currents are generated in it and magnetic field of opposite polarity as the applied one arises. Due to the internal resistance of the conductive material, the eddy currents will be dissipated into heat (Joule heating). Conventional domestic water heaters utilize gas burners or electric resistance heating elements to heat the water in the tank and substantial part of the energy to use for it is wasted. In this paper the origin of electromagnetic induction heat generated by wind turbine in special heat exchange camera connected to water boiler is discussed and material evaluation performed using mathematical modelling (comparing the 2D finite element model with analytical and numerical calculation results).

  14. Three-axis orthogonal transceiver coil for eddy current sounding

    Science.gov (United States)

    Sukhanov, D.; Zavyalova, K.; Goncharik, M.

    2017-08-01

    We propose the new structure of three-axis transceiver magnetic-induction coil for eddy current probing. Due to the orientation of the coils, the direct signal from the transmitting coil to the receiving coil is minimized, which provided a high dynamic range. Sensitivity in all directions is provided by combining coils of different orientations. Numerical simulation and experimental studies of such a system have been carried out and confirmed the applicability of the proposed method and the mathematical model.

  15. Advances in NDT and Materials Characterization by Eddy Currents

    OpenAIRE

    Almeida, G.; Gonzalez, J.; Rosado, L.; Vilaça, P.; Santos, T.G.

    2013-01-01

    VK: T20309 New materials and production technologies demand improved non-destructive techniques for inspection and defect evaluation, especially when critical safety applications are involved. In this paper a new non-destructive testing (NDT) system is presented. The innovative system is composed by a new type of eddy currents probe, electronic devices for signal generation, conditioning and conversion, automated mechanized scanning and analysis software. This new probe provides enhanced l...

  16. Eddy current testing probe optimization using a parallel genetic algorithm

    Directory of Open Access Journals (Sweden)

    Dolapchiev Ivaylo

    2008-01-01

    Full Text Available This paper uses the developed parallel version of Michalewicz's Genocop III Genetic Algorithm (GA searching technique to optimize the coil geometry of an eddy current non-destructive testing probe (ECTP. The electromagnetic field is computed using FEMM 2D finite element code. The aim of this optimization was to determine coil dimensions and positions that improve ECTP sensitivity to physical properties of the tested devices.

  17. Permanent Magnet Eddy Current Loss Analysis of a Novel Motor Integrated Permanent Magnet Gear

    DEFF Research Database (Denmark)

    Zhang, Yuqiu; Lu, Kaiyuan; Ye, Yunyue

    2012-01-01

    In this paper, a new motor integrated permanent magnet gear (MIPMG) is discussed. The focus is on eddy current loss analysis associated to permanent magnets (PMs). A convenient model of MIPMG is provided based on 2-D field-motion coupled time-stepping finite element method for transient eddy...... current analysis. The model takes the eddy current effect of PMs into account in determination of the magnetic field in the air-gap and in the magnet regions. The eddy current losses generated in the magnets are properly interpreted. Design improvements for reducing the eddy current losses are suggested...

  18. A tale of two eddies: The biophysical characteristics of two contrasting cyclonic eddies in the East Australian Current System

    Science.gov (United States)

    Roughan, M.; Keating, S. R.; Schaeffer, A.; Cetina Heredia, P.; Rocha, C.; Griffin, D.; Robertson, R.; Suthers, I. M.

    2017-03-01

    Mesoscale cyclonic eddies are known to be highly productive. Less well-known are the dynamics and productivity of smaller cyclonic eddies, known as frontal eddies, that form on the landward side of western boundary currents. In this study, we investigate the physical and biogeochemical properties of two contrasting cyclonic eddies in the East Australian Current (EAC). The first ("Murphy"), a mesoscale cyclonic eddy that formed at ˜28°S with a diameter of ˜160 km and high surface chlorophyll-a concentrations, which lived ˜47 days. The second ("Freddy"), a smaller frontal eddy (˜35 km diameter) that formed from a shelf water billow ˜7 days prior to sampling at ˜31.5°S and was advected off the shelf along the EAC front (from ˜200 m to 4000 m of water). Both eddies were at least 1000 m deep with a similar steric height anomaly. We introduce and employ "the method of closest approach" using shipboard ADCP velocities to estimate the eddy centers, which reveals significant tilting through the water column. We estimate rotation rates of 4-10 days and 1-9 days and Rossby numbers 0.25-0.1 and 0.6-0.1, from the surface to 600 m for Murphy and Freddy, respectively. High-resolution altimetry measurements from the SARAL/AltiKA satellite provide estimates of the ageostrophic component of rotation. Our results show that the frontal eddy is significantly more ageostrophic, energetic, and productive than the mesoscale cyclone, despite its small size and short life (˜4 weeks). We suggest that frontal eddies have potential to contribute significantly to the net productivity of the Tasman Sea region.Plain Language SummaryWe present the first depth observations of a small cold core eddy which formed along the landward front of the East Australian Current. We contrast the observations with a typical larger cold core eddy. The observations were collected from a dedicated cruise aboard a research vessel. We show that this small Frontal Eddy is very dynamic feature. It rotates

  19. Outer rotor eddy current heater for wind turbines

    Directory of Open Access Journals (Sweden)

    Tudorache Tiberiu

    2016-01-01

    Full Text Available This paper proposes a conversion system of wind energy into thermal energy by means of an outer rotor permanent magnet eddy current heater. The main advantages of this device are the following: compactness, easy temperature control by water flow rate regulation, reduced energy cost per kWh, possibility of combination with other heating systems. The analysis presented in the paper is based on the finite element method and its purpose is to optimize the device and to evaluate its performance and operation characteristics such as: analysis of demagnetization level of permanent magnets, output power–rotor speed and electromagnetic torque–rotor speed curves.

  20. Study of pseudo soldering based on eddy current pulsed thermography

    Science.gov (United States)

    Zhou, Xiuyun; Xue, Yun; Chen, Yaqiu; Lu, Xiaochuan; Liu, Zhen

    2017-09-01

    Pseudo soldering defects can break the electrical and mechanical connection between components and the print circuit board and eventually cause failure of the whole electronic equipment. In this letter, the eddy current pulsed thermography (ECPT) method was used for defect inspection of small-sized solder joints. The identification of defects of solder joints is based on the heat transfer between various component structures. The experimental results indicated that the ECPT method can be effectively used for defect detection and location of the solder joints. In addition, it can distinguish different degrees of pseudo soldering.

  1. Development, computer simulation and performance testing in sodium of an eddy current flowmeter

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Prashant, E-mail: pacific@igcar.gov.i [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India); Suresh Kumar, S.; Nashine, B.K.; Veerasamy, R.; Krishnakumar, B.; Kalyanasundaram, P.; Vaidyanathan, G. [Indira Gandhi Centre for Atomic Research, Kalpakkam 603 102 (India)

    2010-03-15

    Sodium is used as a coolant in Liquid Metal Fast Breeder Reactor (LMFBR). Sodium flow measurement is of prime importance both from the operational and safety aspects of a fast reactor. Various types of flowmeters namely permanent magnet, saddle type and eddy current flowmeters are used in FBRs. From the safety point of view flow through the core should be assured under all operating conditions. This requires a flow sensor which can withstand the high temperature sodium environment and can meet the dimensional constraints and be amenable to maintenance. Eddy current flowmeter (ECFM) is one such device which meets these requirements. It is meant for measuring flow in PFBR primary pump and also at the outlets of the fuel sub-assemblies to detect flow blockage. A simulation model of ECFM was made and output of ECFM was predicted for various flowrates and temperatures. The simulation model was validated by testing in a sodium loop. This paper deals with the design, simulation and tests conducted in sodium for the eddy current flowmeter for use in the Prototype Fast Breeder Reactor (PFBR).

  2. A comparison of the structure, properties, and water mass composition of quasi-isotropic eddies in western boundary currents in an eddy-resolving ocean model

    Science.gov (United States)

    Rykova, Tatiana; Oke, Peter R.; Griffin, David A.

    2017-06-01

    Using output from a near-global eddy-resolving ocean model, we analyse the properties and characteristics of quasi-isotropic eddies in five Western Boundary Current (WBC) regions, including the extensions of the Agulhas, East Australian Current (EAC), Brazil-Malvinas Confluence (BMC), Kuroshio and Gulf Stream regions. We assess the model eddies by comparing to satellite and in situ observations, and show that most aspects of the model's representation of eddies are realistic. We find that the mean eddies differ dramatically between these WBC regions - all with some unique and noteworthy characteristics. We find that the vertical displacement of isopycnals of Agulhas eddies is the greatest, averaging 350-450 m at depths of over 800-900 m. EAC (BMC) eddies are the least (most) barotropic, with only 50% (85-90%) of the velocity associated with the barotropic mode. Kuroshio eddies are the most stratified, resulting in small isopycnal displacement, even for strong eddies; and Gulf Stream eddies carry the most heat. Despite their differences, we explicitly show that the source waters for anticyclonic eddies are a mix of the WBC water (from the boundary current itself) and water that originates equatorward of the WBC eddy-field; and cyclonic eddies are a mix of WBC water and water that originates poleward of the WBC eddy-field.

  3. Eddy current quality control of soldered current-carrying busbar splices of superconducting magnets

    CERN Document Server

    Kogan, L; Savary, F; Principe, R; Datskov, V; Rozenfel'd, E; Khudjakov, B

    2015-01-01

    The eddy current technique associated with a U-shaped transducer is studied for the quality control of soldered joints between superconducting busbars ('splices'). Two other quality control techniques, based on X-rays and direct measurement of the electrical resistance, are also studied for comparison. A comparative analysis of the advantages and disadvantages of these three methods in relation to the quality control of soldered superconducting busbar cables enclosed in copper shells is used for benchmarking. The results of inspections with the U-shaped eddy current transducer carried out on several sample joints presenting different types of soldering defects show the potential of this type of nondestructive (ND) quality control technique.

  4. Non-destructive testing of composite materials used in military applications by eddy current thermography method

    Science.gov (United States)

    Swiderski, Waldemar

    2016-10-01

    Eddy current thermography is a new NDT-technique for the detection of cracks in electro conductive materials. It combines the well-established inspection techniques of eddy current testing and thermography. The technique uses induced eddy currents to heat the sample being tested and defect detection is based on the changes of induced eddy currents flows revealed by thermal visualization captured by an infrared camera. The advantage of this method is to use the high performance of eddy current testing that eliminates the known problem of the edge effect. Especially for components of complex geometry this is an important factor which may overcome the increased expense for inspection set-up. The paper presents the possibility of applying eddy current thermography method for detecting defects in ballistic covers made of carbon fiber reinforced composites used in the construction of military vehicles.

  5. Gas turbine coatings eddy current quantitative and qualitative evaluation

    Science.gov (United States)

    Ribichini, Remo; Giolli, Carlo; Scrinzi, Erica

    2017-02-01

    Gas turbine blades (buckets) are among the most critical and expensive components of the engine. Buckets rely on protective coatings in order to withstand the harsh environment in which they operate. The thickness and the microstructure of coatings during the lifespan of a unit are fundamental to evaluate their fitness for service. A frequency scanning Eddy Current instrument can allow the measurement of the thickness and of physical properties of coatings in a Non-Destructive manner. The method employed relies on the acquisition of impedance spectra and on the inversion of the experimental data to derive the coating properties and structure using some assumptions. This article describes the experimental validation performed on several samples and real components in order to assess the performance of the instrument as a coating thickness gage. The application of the technique to support residual life assessment of serviced buckets is also presented.

  6. Detection of foreign objects using bobbin probe eddy current test

    Energy Technology Data Exchange (ETDEWEB)

    Jung, Hee Sung; Kweon, Young Ho; Lee, Dong Ha; Shin, Wook Jo; Yim, Chan Ki [ECT Group, Sae-An Engineering Corporation, Seoul (Korea, Republic of)

    2016-08-15

    Residual foreign objects at the secondary side (top of the tubesheet and tube support plates) of a steam generator are likely to cause a leak by causing wear in the tube. The extent of wear is significantly affected by the material, shape, and size of the foreign object, and the corrosion properties of the tube. The presence of foreign objects at the top of the tubesheet and tube support plates has been identified using remote visual inspection methods such as the foreign object search and retrieval and eddy current test (ECT). The detection of the residual foreign object at the secondary side of a steam generator has limitations that depend on the material properties and the condition of contact with the tube. In this study, which is vertical and horizontal from the upper tubesheet, the corresponding bobbin ECT signals were collected and analyzed to measure its ability to detect foreign objects.

  7. Computer programs for eddy-current defect studies

    Energy Technology Data Exchange (ETDEWEB)

    Pate, J. R.; Dodd, C. V. [Oak Ridge National Lab., TN (USA)

    1990-06-01

    Several computer programs to aid in the design of eddy-current tests and probes have been written. The programs, written in Fortran, deal in various ways with the response to defects exhibited by four types of probes: the pancake probe, the reflection probe, the circumferential boreside probe, and the circumferential encircling probe. Programs are included which calculate the impedance or voltage change in a coil due to a defect, which calculate and plot the defect sensitivity factor of a coil, and which invert calculated or experimental readings to obtain the size of a defect. The theory upon which the programs are based is the Burrows point defect theory, and thus the calculations of the programs will be more accurate for small defects. 6 refs., 21 figs.

  8. Study on classical and excess eddy currents losses of Terfenol-D

    Energy Technology Data Exchange (ETDEWEB)

    Talebian, Soheil; Hojjat, Yousef [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Ghodsi, Mojtaba [Department of Mechanical and Industrial Engineering, Sultan Qaboos University, Muscat (Oman); Karafi, Mohammad Reza [Department of Mechanical Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of)

    2015-08-15

    In the present paper, classical and excess eddy currents losses of Terfenol-D are studied and effects of magnetic field frequency, peak of magnetic flux density and diameter of Terfenol-D on the eddy currents losses are investigated. To provide reliable data for the purpose of the paper, an experimental laboratory is fabricated and used to obtain major and minor hysteresis loops of Terfenol-D at different frequencies. In theoretical study, initially an analytical model based on uniform distribution of magnetic flux is developed which yields to calculation of classical eddy currents losses. Then, another eddy currents model based on non-uniform distribution of magnetic flux and nonlinear diffusion of electromagnetic fields is presented. The difference between output values of the two models is identified as excess eddy currents losses. Obtained results show that the values of excess losses are generally larger than classical losses and applying just classical model leads to wrong calculation of actual value of eddy currents losses. For the results obtained from two above models, empirical models with respect to the magnetic field frequency and the peak value of magnetic flux density are achieved which can predict the eddy currents losses precisely. To validate the empirical relations, experiments are repeated at a new frequency and values of power losses calculated from analytical equations are compared with the predicted values of the empirical models. The results point towards possibility to use the obtained empirical relations in order to calculate the classical and excess eddy currents losses of Terfenol-D at the frequencies below 200 Hz and different values of magnetic flux density. - Highlights: • Classical eddy currents loss of Terfenol-D is studied using Maxwell's laws. • Excess eddy currents loss of Terfenol-D is studied using Mayergoyz nonlinear model. • Effects of Terfenol-D geometry on the eddy currents losses are investigated. • Power

  9. Lagrangian and Eulerian characterization of two counter-rotating submesoscale eddies in a western boundary current

    Science.gov (United States)

    Mantovanelli, Alessandra; Keating, Shane; Wyatt, Lucy R.; Roughan, Moninya; Schaeffer, Amandine

    2017-06-01

    In recent decades, high-spatial resolution ocean radar and satellite imagery measurements have revealed a complex tangle of submesoscale filaments and eddies, in the surface velocity, temperature, and chlorophyll a fields. We use a suite of high-resolution data to characterize two counter-rotating, short-lived eddies formed at the front between the warm East Australian Current (EAC) and temperate coastal waters (30°S, Eastern Australia). In this region, submesoscale filaments and short-lived eddies are dynamically generated and decay at time scales of hours to days. Dominant cyclonic filaments of O(1) Rossby number formed along frontal jets and eddy boundaries, generating localized ageostrophic circulations at the submesoscale. Measurements of over-ocean wind direction and surface currents from high-frequency radars reveal the influence of the short-term, small-scale wind forcing on the surface circulation, enhancement of the horizontal shear, frontal jet destabilization, and the generation and decay of the cyclonic eddy. By contrast, the anticyclonic eddy formation was most likely associated with EAC mesoscale instability and anticyclonic vorticity. Lagrangian tracks show that surface particles can be temporarily trapped in the eddies and frontal convergent zones, limiting their transport. Mixing between EAC-derived and coastal waters was increased along the frontal regions, and particles starting at the divergent regions around the eddies experienced significant dispersion at submesoscales. The cyclonic cold-core eddy entrained high chlorophyll a shelf waters on its convergent side, suggesting spiral eddy cyclogenesis.

  10. Single-tone and Polyharmonic Eddy Current Metal Detection and Non-Destructive Testing Education Software

    Science.gov (United States)

    Svatoš, J.

    2016-11-01

    This paper describes the design of a measuring chain for polyharmonic metal detectors used for education in laboratory exercises at Czech Technical University in Prague, Faculty of Electrical Engineering, Department of Measurement. The Measuring chain is composed of DDS signal generator, Digitiser and PC with software programmed in Labview. Eddy current principles or more specifically eddy current metal detectors are an important part of nondestructive testing, instrumentations and measurement. A short introduction to the background and principles of eddy current metal detectors are presented. Next part of the article deals with a brief description of the most common methods, as well as, non-traditional polyharmonic methods for eddy current metal detection. The following part contains an implementation of the proposed algorithms in LabVIEW graphical programming language. Finally, the created program for education of eddy current metal detectors and results obtained on the metal detector ATMID are discussed.

  11. A Numerical Study of Loop Current Intrusions and Eddy Shedding.

    Science.gov (United States)

    1980-06-20

    subsequently eddy shedding. The second is that the Campeche Bank blocks the westward spreading of the Loop and also inhibits the eddy shedding process...One experiment to test these hypotheses involved totally removing both the Campeche Bank and the bottom slope on inflow. Figure 27a shows the modified...26b). Clearly, neither the bottom slope on inflow nor the Campeche Bank topography are responsible for this I steady regime. At the beginning of year

  12. Eddy current testing system for bottom mounted instrumentation welds

    Directory of Open Access Journals (Sweden)

    Kobayashi Noriyasu

    2015-01-01

    Full Text Available The capability of eddy current testing (ECT for the bottom mounted instrumentation (BMI weld area of reactor vessel in a pressurized water reactor was demonstrated by the developed ECT system and procedure. It is difficult to position and move the probe on the BMI weld area because the area has complexly curved surfaces. The space coordinates and the normal vectors at the scanning points were calculated as the scanning trajectory of probe based on the measured results of surface shape on the BMI mock-up. The multi-axis robot was used to move the probe on the mock-up. Each motion-axis position of the robot corresponding to each scanning point was calculated by the inverse kinematic algorithm. In the mock-up test, the probe was properly contacted with most of the weld surfaces. The artificial stress corrosion cracking of approximately 6 mm in length and the electrical-discharge machining slit of 0.5 mm in length, 1 mm in depth and 0.2 mm in width given on the weld surface were detected. From the probe output voltage, it was estimated that the average probe tilt angle on the surface under scanning was 2.6°.

  13. Current signature sensor

    Science.gov (United States)

    Perotti, Jose M. (Inventor); Lucena, Angel (Inventor); Ihlefeld, Curtis (Inventor); Burns, Bradley (Inventor); Bassignani, Karin E. (Inventor)

    2005-01-01

    A solenoid health monitoring system uses a signal conditioner and controller assembly in one embodiment that includes analog circuitry and a DSP controller. The analog circuitry provides signal conditioning to the low-level raw signal coming from a signal acquisition assembly. Software running in a DSP analyzes the incoming data (recorded current signature) and determines the state of the solenoid whether it is energized, de-energized, or in a transitioning state. In one embodiment, the software identifies key features in the current signature during the transition phase and is able to determine the health of the solenoid.

  14. Non-destructive Testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

    Science.gov (United States)

    Lu, D. F.; Fan, Chang-Xin; Ruan, J. Z.; Han, S. G.; Wong, K. W.; Sun, G. F.

    1995-01-01

    A SQUID is the most sensitive device to detect change in magnetic field. A nondestructive testing (NDT) device using high temperature SQUID's and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUID's. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDT device will have a significant impact on metal corrosion or crack detection technology.

  15. Non-destructive testing (NDT) of metal cracks using a high Tc rf-SQUID and eddy current method

    Energy Technology Data Exchange (ETDEWEB)

    Lu, D.F.; Fan, C.; Ruan, J.Z. [Midwest Superconductivity Inc., Lawrence, KS (United States)] [and others

    1994-12-31

    A SQUID is the most sensitive device to detect change in magnetic field. A non-destructive testing (NDT) device using high temperature SQUIDs and eddy current method will be much more sensitive than those currently used eddy current systems, yet much cheaper than one with low temperature SQUIDs. In this paper, we present our study of such a NDT device using a high temperature superconducting rf-SQUID as a gradiometer sensor. The result clearly demonstrates the expected sensitivity of the system, and indicates the feasibility of building a portable HTS SQUID NDT device with the help from cryocooler industry. Such a NDT device will have a significant impact on metal corrosion or crack detection technology.

  16. Analysis of eddy current induced in track on medium-low speed maglev train

    Science.gov (United States)

    Li, Guanchun; Jia, Zhen; He, Guang; Li, Jie

    2017-06-01

    Electromagnetic levitation (EMS) maglev train relies on the attraction between the electromagnets and rails which are mounted on the train to achieve suspension. During the movement, the magnetic field generated by the electromagnet will induce the eddy current in the orbit and the eddy current will weaken the suspended magnetic field. Which leads to the attenuation of the levitation force, the increases of suspension current and the degradation the suspension performance. In this paper, the influence of eddy current on the air gap magnetic field is solved by theoretical analysis, and the correction coefficient of air gap magnetic field is fitted according to the finite element data. The levitation force and current are calculated by the modified formula, and the velocity curves of the levitation force and current are obtained. The results show that the eddy current effect increases the load power by 61.9% in the case of heavy loads.

  17. Estimation of stress distribution in ferromagnetic tensile specimens using low cost eddy current stress measurement system and BP neural network.

    Directory of Open Access Journals (Sweden)

    Jianwei Li

    Full Text Available Estimation of the stress distribution in ferromagnetic components is very important for evaluating the working status of mechanical equipment and implementing preventive maintenance. Eddy current testing technology is a promising method in this field because of its advantages of safety, no need of coupling agent, etc. In order to reduce the cost of eddy current stress measurement system, and obtain the stress distribution in ferromagnetic materials without scanning, a low cost eddy current stress measurement system based on Archimedes spiral planar coil was established, and a method based on BP neural network to obtain the stress distribution using the stress of several discrete test points was proposed. To verify the performance of the developed test system and the validity of the proposed method, experiment was implemented using structural steel (Q235 specimens. Standard curves of sensors at each test point were achieved, the calibrated data were used to establish the BP neural network model for approximating the stress variation on the specimen surface, and the stress distribution curve of the specimen was obtained by interpolating with the established model. The results show that there is a good linear relationship between the change of signal modulus and the stress in most elastic range of the specimen, and the established system can detect the change in stress with a theoretical average sensitivity of -0.4228 mV/MPa. The obtained stress distribution curve is well consonant with the theoretical analysis result. At last, possible causes and improving methods of problems appeared in the results were discussed. This research has important significance for reducing the cost of eddy current stress measurement system, and advancing the engineering application of eddy current stress testing.

  18. Heat balance and eddies in the Peru-Chile current system

    Energy Technology Data Exchange (ETDEWEB)

    Colas, Francois; McWilliams, James C.; Kurian, Jaison [University of California, Institute of Geophysics and Planetary Physics, Los Angeles, CA (United States); Capet, Xavier [Laboratoire de Physique des Oceans, Ifremer, Plouzane (France)

    2012-07-15

    The Peru-Chile current System (PCS) is a region of persistent biases in global climate models. It has strong coastal upwelling, alongshore boundary currents, and mesoscale eddies. These oceanic phenomena provide essential heat transport to maintain a cool oceanic surface underneath the prevalent atmospheric stratus cloud deck, through a combination of mean circulation and eddy flux. We demonstrate these behaviors in a regional, quasi-equilibrium oceanic model that adequately resolves the mesoscale eddies with climatological forcing. The key result is that the atmospheric heating is large (>50 W m{sup -2}) over a substantial strip >500 km wide off the coast of Peru, and the balancing lateral oceanic flux is much larger than provided by the offshore Ekman flux alone. The atmospheric heating is weaker and the coastally influenced strip is narrower off Chile, but again the Ekman flux is not sufficient for heat balance. The eddy contribution to the oceanic flux is substantial. Analysis of eddy properties shows strong surface temperature fronts and associated large vorticity, especially off Peru. Cyclonic eddies moderately dominate the surface layer, and anticyclonic eddies, originating from the nearshore poleward Peru-Chile Undercurrent (PCUC), dominate the subsurface, especially off Chile. The sensitivity of the PCS heat balance to equatorial intra-seasonal oscillations is found to be small. We demonstrate that forcing the regional model with a representative, coarse-resolution global reanalysis wind product has dramatic and deleterious consequences for the oceanic circulation and climate heat balance, the eddy heat flux in particular. (orig.)

  19. Eddy current characterization of small cracks using least square support vector machine

    Science.gov (United States)

    Chelabi, M.; Hacib, T.; Le Bihan, Y.; Ikhlef, N.; Boughedda, H.; Mekideche, M. R.

    2016-04-01

    Eddy current (EC) sensors are used for non-destructive testing since they are able to probe conductive materials. Despite being a conventional technique for defect detection and localization, the main weakness of this technique is that defect characterization, of the exact determination of the shape and dimension, is still a question to be answered. In this work, we demonstrate the capability of small crack sizing using signals acquired from an EC sensor. We report our effort to develop a systematic approach to estimate the size of rectangular and thin defects (length and depth) in a conductive plate. The achieved approach by the novel combination of a finite element method (FEM) with a statistical learning method is called least square support vector machines (LS-SVM). First, we use the FEM to design the forward problem. Next, an algorithm is used to find an adaptive database. Finally, the LS-SVM is used to solve the inverse problems, creating polynomial functions able to approximate the correlation between the crack dimension and the signal picked up from the EC sensor. Several methods are used to find the parameters of the LS-SVM. In this study, the particle swarm optimization (PSO) and genetic algorithm (GA) are proposed for tuning the LS-SVM. The results of the design and the inversions were compared to both simulated and experimental data, with accuracy experimentally verified. These suggested results prove the applicability of the presented approach.

  20. Mathematical Modeling of Eddy-Current Loss for a New Induction Heating Device

    Directory of Open Access Journals (Sweden)

    Hai Du

    2014-01-01

    Full Text Available A new induction heating device is presented in this paper. This device can convert mechanical energy into heat energy by utilizing eddy currents, which are induced by rotating permanent magnets. A mathematical model is established for estimating eddy-current loss of the device. The distribution of induced currents and the resultant magnetic field intensity are considered in the process of modeling the eddy-current loss and so is the mutual influence of the electric field between neighborhood pole projection areas. Particularly, the skin effect is considered by correcting the numerical integral domain of eddy current density, which has great effect on the calculating results. Based on specific examples, the effectiveness and correctness of proposed model are proved by finite element analysis. The results show that the mathematical model can provide important reference for design and structure optimization of the device.

  1. Computational electromagnetics and model-based inversion a modern paradigm for eddy-current nondestructive evaluation

    CERN Document Server

    Sabbagh, Harold A; Sabbagh, Elias H; Aldrin, John C; Knopp, Jeremy S

    2013-01-01

    Computational Electromagnetics and Model-Based Inversion: A Modern Paradigm for Eddy Current Nondestructive Evaluation describes the natural marriage of the computer to eddy-current NDE. Three distinct topics are emphasized in the book: (a) fundamental mathematical principles of volume-integral equations as a subset of computational electromagnetics, (b) mathematical algorithms applied to signal-processing and inverse scattering problems, and (c) applications of these two topics to problems in which real and model data are used. By showing how mathematics and the computer can solve problems more effectively than current analog practices, this book defines the modern technology of eddy-current NDE. This book will be useful to advanced students and practitioners in the fields of computational electromagnetics, electromagnetic inverse-scattering theory, nondestructive evaluation, materials evaluation and biomedical imaging. Users of eddy-current NDE technology in industries as varied as nuclear power, aerospace,...

  2. Corrosion Assessment of Steel Bars Used in Reinforced Concrete Structures by Means of Eddy Current Testing.

    Science.gov (United States)

    de Alcantara, Naasson P; da Silva, Felipe M; Guimarães, Mateus T; Pereira, Matheus D

    2015-12-24

    This paper presents a theoretical and experimental study on the use of Eddy Current Testing (ECT) to evaluate corrosion processes in steel bars used in reinforced concrete structures. The paper presents the mathematical basis of the ECT sensor built by the authors; followed by a finite element analysis. The results obtained in the simulations are compared with those obtained in experimental tests performed by the authors. Effective resistances and inductances; voltage drops and phase angles of wound coil are calculated using both; simulated and experimental data; and demonstrate a strong correlation. The production of samples of corroded steel bars; by using an impressed current technique is also presented. The authors performed experimental tests in the laboratory using handmade sensors; and the corroded samples. In the tests four gauges; with five levels of loss-of-mass references for each one were used. The results are analyzed in the light of the loss-of-mass and show a strong linear behavior for the analyzed parameters. The conclusions emphasize the feasibility of the proposed technique and highlight opportunities for future works.

  3. Eddy current inspection of power plant heat-exchanger tubing in the USA

    Energy Technology Data Exchange (ETDEWEB)

    Fishkin, P.; Nash, J. [MQS Inspection, Inc., Chicago, IL (United States)

    1995-02-01

    The latest experience in the eddy current inspection of heat-exchanger tubing by means of ID probes is reported and generalized. The authors demonstrate the feasibility of using modern, general-purpose, digital eddy current flaw detectors equipped with microprocessors, displays, the capability for recording inspection results on paper or magnetic media, sound and visual alarms. The NDE personnel qualification and certification requirements are described.

  4. Quantitative void fraction detection with an eddy current flowmeter for generation IV Sodium cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M. [Institut de Mecanique des Fluides de Toulouse, 2 Allee du Professeur Camille Soula, 31400 Toulouse, (France); French Atomic Energy and Alternative Energies Commission (CEA), DEN, Laboratory of Instrumentation and technological Test, Cadarache, 13108 Saint Paul lez Durance, (France); Tordjeman, Ph.; Bergez, W. [Institut de Mecanique des Fluides de Toulouse, 2 Allee du Professeur Camille Soula, 31400 Toulouse, (France); Cavaro, M.; Paumel, K.; Jeannot, J. P. [French Atomic Energy and Alternative Energies Commission (CEA), DEN, Laboratory of Instrumentation and technological Test, Cadarache, 13108 Saint Paul lez Durance, (France)

    2015-07-01

    This study was carried out to understand the response of an eddy current type flowmeter in two phase liquid-metal flow. We use the technique of ellipse fit and correlate the fluctuations in the angle of inclination of this ellipse with the void fraction. The effects of physical parameters such as coil excitation frequency and flow velocity have been studied. The results show the possibility of using an eddy current flowmeter as a gas detector for large void fractions. (authors)

  5. Quantitative void fraction measurement with an eddy current flowmeter for generation IV Sodium cooled Fast Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, M. [Institut de Mecanique des Fluides de Toulouse, 2 Allee du Professeur Camille Soula, 31400 Toulouse (France); CEA, DEN, Nuclear Technology Department, F-13108 Saint-Paul-lez-Durance (France); Tordjeman, Ph.; Bergez, W. [Institut de Mecanique des Fluides de Toulouse, 2 Allee du Professeur Camille Soula, 31400 Toulouse (France); Cavaro, M.; Paumel, K.; Jeannot, J.P. [CEA, DEN, Nuclear Technology Department, F-13108 Saint-Paul-lez-Durance (France)

    2015-07-01

    This study was carried out to understand the response of an eddy current type flowmeter in two phase liquid-metal flow. We use the technique of ellipse fit and correlate the fluctuations in the angle of inclination of this ellipse with the void fraction. The effects of physical parameters such as coil excitation frequency and flow velocity have been studied. The results show the possibility of using an eddy current flowmeter as a gas detector for large void fractions. (authors)

  6. Eddy current density asymmetric distribution of damper bars in bulb tubular turbine generator

    Directory of Open Access Journals (Sweden)

    Qiu Hongbo

    2017-09-01

    Full Text Available The major reasons that cause the damage of damper bars in the leeward side are found in this paper. It provides a route for the structure optimization design of a hydro generator. Firstly, capacity of a 24 MW bulb tubular turbine generator is taken as an example in this paper. The transient electromagnetic field model is established, and the correctness of the model is verified by the comparison of experimental results and simulation data. Secondly, when the generator is operated at rated condition, the eddy current density distributions of damper bars are studied. And the asymmetric phenomenon of the eddy current density on damper bars is discovered. The change laws of the eddy currents in damper bars are determined through further analysis. Thirdly, through the study of eddy current distributions under different conditions, it is confirmed that the stator slots and armature reaction are the main factors to affect the asymmetric distribution of the eddy current in damper bars. Finally, the studies of the magnetic density distribution and theoretical analysis revealed the asymmetric distribution mechanism of eddy current density.

  7. Feasibility of conductivity imaging using subject eddy currents induced by switching of MRI gradients.

    Science.gov (United States)

    Oran, Omer Faruk; Ider, Yusuf Ziya

    2017-05-01

    To investigate the feasibility of low-frequency conductivity imaging based on measuring the magnetic field due to subject eddy currents induced by switching of MRI z-gradients. We developed a simulation model for calculating subject eddy currents and the magnetic fields they generate (subject eddy fields). The inverse problem of obtaining conductivity distribution from subject eddy fields was formulated as a convection-reaction partial differential equation. For measuring subject eddy fields, a modified spin-echo pulse sequence was used to determine the contribution of subject eddy fields to MR phase images. In the simulations, successful conductivity reconstructions were obtained by solving the derived convection-reaction equation, suggesting that the proposed reconstruction algorithm performs well under ideal conditions. However, the level of the calculated phase due to the subject eddy field in a representative object indicates that this phase is below the noise level and cannot be measured with an uncertainty sufficiently low for accurate conductivity reconstruction. Furthermore, some artifacts other than random noise were observed in the measured phases, which are discussed in relation to the effects of system imperfections during readout. Low-frequency conductivity imaging does not seem feasible using basic pulse sequences such as spin-echo on a clinical MRI scanner. Magn Reson Med 77:1926-1937, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  8. The Investigation of Separability of Particles Smaller Than 5 mm by Eddy Current Separation Technology. Part I : Rotating Type Eddy Current Separators

    NARCIS (Netherlands)

    Zhang, S.; Rem, P.C.; Forssberg, E.

    1999-01-01

    Owing to the growing emergence of the end-of-life electrical and electronic products with complex material structures and an ever-diminishing particle size of the valuable metals involved, development of eddy current separators (ECS) has been targeting selective separation of small non-ferrous metal

  9. Eddy Heat Fluxes across the Antarctic Circumpolar Current in Northern Drake Passage

    Science.gov (United States)

    Watts, D. R.; Tracey, K. L.; Donohue, K. A.; Chereskin, T. K.

    2012-12-01

    A local dynamics array of 24 current and pressure recording inverted echo sounders (CPIES) was deployed as part of the cDrake experiment for 4 years centered near 57S, 63W spanning a local maximum eddy kinetic energy region between the Subantarctic Front and Polar Front. The CPIES array provides full water-column estimates of velocity and temperature that were mapped to quantify and characterize eddy heat flux. Objective mapping was used to separate the total eddy heat fluxes into a nondivergent (rotational) part that recirculates around mean temperature-variance structures and a divergent part that accounts for the net eddy flux of heat across the Antarctic Circumpolar Current. The vertical shear, aligned along isotherms, is equivalent-barotropic and contributes only nondivergent heat flux. In contrast, the dynamically important component of eddy heat flux that transfers energy from the mean to the eddy field is driven by nearly depth-independent geostrophic currents that can cross the temperature front. Thus as in Bishop [2012], the coupling between the nearly depth-independent currents measured at the bottom and the temperatures in the baroclinic front accounts for all the divergent component of eddy heat flux. The separation reveals divergent heat fluxes that typically are oriented differently and have magnitudes a few times smaller than the total eddy heat fluxes. The mapped annual-mean eddy heat fluxes have a spatial structure that is relatively consistent from year-to-year and exhibit a region of strong poleward divergent fluxes just downstream of a prominent topographic ridge (Shackleton Fracture Zone). The fluxes peak in the upper water column at 100-200 kW m^{-2} near 200 m depth and decrease to 10-15% as large by 600 m depth, below which they are relatively constant and coherent to the sea floor. In these "hot spots" of eddy heat flux the vertically-integrated poleward divergent fluxes are 50 - 100 MW m^{-1}. The time series of daily heat flux show that

  10. Variability of the Somali Current and eddies during the southwest monsoon regimes

    Science.gov (United States)

    Trott, Corinne B.; Subrahmanyam, Bulusu; Murty, V. S. N.

    2017-09-01

    The meso-scale eddies and currents in the Arabian Sea are analyzed using different satellite observations, Simple Oceanic Data Assimilation (SODA) reanalysis, and Ocean Reanalysis System 4 (ORAS4) from 1993 to 2016 to investigate the impacts of Southwest (SW) Monsoon strength on Somali Current (SC) mesoscale circulations such as the Great Whirl (GW), the Socotra Eddy (SE), the Southern Gyre (SG), and smaller eddies. Increased Ekman pumping during stronger SW monsoons strengthens coastal upwelling along the Somali coast. The Arabian Sea basin-wide anticyclonic circulation and presence of the GW form mesoscale circulation patterns favourable to advection of upwelled waters eastward into the central Arabian Sea. In September, after the SW monsoon winds reach peak strength in July and August, a higher number of discrete anticyclonic eddies with higher (> 20 cm) sea surface height anomalies develop in strong and normal intensity SW monsoon seasons than weaker SW monsoon seasons.

  11. Fiber optic lightning current sensor

    Science.gov (United States)

    Ye, Miaoyuan; Li, Kaicheng; Wang, Jing-Gang; Feng, Chunmei

    1995-09-01

    A fiber-optic sensor has been developed to measure the lightening current. The lightening current which induces birefringence in a glass loop is to modulate a linearly polarized optical beam ((lambda) equals 0.85 micrometers ). The modulated optical information is transmitted to a PIN through an optical cable and converted to the electrical signal. A high-speed data acquisition system is used to sample the pulse signal. The waveform, rise time, peak value, and frequency components of the pulse signal can be shown on the screen of the computer.

  12. Key factors of eddy current separation for recovering aluminum from crushed e-waste.

    Science.gov (United States)

    Ruan, Jujun; Dong, Lipeng; Zheng, Jie; Zhang, Tao; Huang, Mingzhi; Xu, Zhenming

    2017-02-01

    Recovery of e-waste in China had caused serious pollutions. Eddy current separation is an environment-friendly technology of separating nonferrous metallic particles from crushed e-waste. However, due to complex particle characters, separation efficiency of traditional eddy current separator was low. In production, controllable operation factors of eddy current separation are feeding speed, (ωR-v), and S p . There is little special information about influencing mechanism and critical parameters of these factors in eddy current separation. This paper provided the special information of these key factors in eddy current separation of recovering aluminum particles from crushed waste refrigerator cabinets. Detachment angles increased as the increase of (ωR-v). Separation efficiency increased with the growing of detachment angles. Aluminum particles were completely separated from plastic particles in critical parameters of feeding speed 0.5m/s and detachment angles greater than 6.61deg. S p /S m of aluminum particles in crushed waste refrigerators ranged from 0.08 to 0.51. Separation efficiency increased as the increase of S p /S m . This enlightened us to develop new separator to separate smaller nonferrous metallic particles in e-waste recovery. High feeding speed destroyed separation efficiency. However, greater S p of aluminum particles brought positive impact on separation efficiency. Greater S p could increase critical feeding speed to offer greater throughput of eddy current separation. This paper will guide eddy current separation in production of recovering nonferrous metals from crushed e-waste. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Design and array signal suggestion of array type pulsed eddy current probe for health monitoring of metal tubes

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Young Kil [Dept. of Electrical Engineering, Kunsan National University, Kunsan (Korea, Republic of)

    2015-10-15

    An array type probe for monitoring metal tubes is proposed in this paper which utilizes peak value and peak time of a pulsed eddy current(PEC) signal. The probe consists of an array of encircling coils along a tube and the outside of coils is shielded by ferrite to prevent source magnetic fields from directly affecting sensor signals since it is the magnetic fields produced by eddy currents that reflect the condition of metal tubes. The positions of both exciter and sensor coils are consecutively moved automatically so that manual scanning is not necessary. At one position of send-receive coils, peak value and peak time are extracted from a sensor PEC signal and these data are accumulated for all positions to form an array type peak value signal and an array type peak time signal. Numerical simulation was performed using the backward difference method in time and the finite element method for spatial analysis. Simulation results showed that peak value increases and the peak appears earlier as the defect depth or length increases. The proposed array signals are shown to be excellent in reflecting the defect location as well as variations of defect depth and length within the array probe.

  14. Eddy current-adjusted plasma shape reconstruction by Cauchy condition surface method on QUEST

    Energy Technology Data Exchange (ETDEWEB)

    Nakamura, K., E-mail: nakamura@triam.kyushu-u.ac.jp [Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka (Japan); Jiang, Y.; Liu, X.L. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, Kasuga, Fukuoka (Japan); Mitarai, O. [Liberal Arts Education Center, Kumamoto Campus, Tokai University, Toroku, Kumamoto (Japan); Kurihara, K.; Kawamata, Y.; Sueoka, M. [Japan Atomic Energy Agency, Naka, Ibaraki (Japan); Hasegawa, M.; Tokunaga, K.; Zushi, H.; Hanada, K.; Fujisawa, A.; Sakamoto, M.; Idei, H.; Kawasaki, S.; Nakashima, H.; Higashijima, A.; Araki, K. [Research Institute for Applied Mechanics, Kyushu University, Kasuga, Fukuoka (Japan)

    2011-10-15

    CCS (Cauchy Condition Surface) method is a numerical approach to reproduce plasma shape, which has good precision in conventional tokamaks. In order to apply it in plasma shape reproduction of ST (Spherical Tokamak), the calculation precision of the CCS method in a spherical tokamak CPD (Compact PWI experimental Device) (B{sub t} = 0.25 T, R = 0.3 m, a = 0.2 m) has been analyzed. The precision was confirmed also in ST and decided to be applied to a spherical tokamak QUEST (B{sub t} = 0.25 T, R = 0.68 m, a = 0.40 m).. In present stage from the magnetic measurement, it is known that the eddy current effect is large in QUEST experiment, and there are no special magnetic measurements for eddy current now, so some proper model should be selected to evaluate the eddy current effect. The eddy current density by not only CS (Center Solenoid) coil but also plasma current is calculated using EDDYCAL (JAEA). The eddy current magnitudes are taken as unknown variables and solved together with plasma shape reconstruction in ohmic discharge and ECCD (Electron Cyclotron Current Drive) discharge.

  15. Eddy current loss in double-sided cored slotless type permanent magnet linear synchronous generator using analytical method

    Science.gov (United States)

    Jang, Gang-Hyeon; Koo, Min-Mo; Seo, Sung-Won; Hong, Keyyong; Choi, Jang-Young

    2017-05-01

    This paper describes the eddy current loss analysis of a double-sided cored slotless-type permanent magnet linear synchronous generator using the space harmonic method. To calculate the eddy current, an analytical solution was derived by applying the Maxwell equation, magnetic vector potential, and Faraday's law in a two-dimensional (2-D) Cartesian coordinate system. Based on the armature reaction field distribution produced by the armature winding current, we obtained an analytical solution for the eddy current density distribution. Then, an analytical solution for eddy current loss induced in a permanent magnet (PM) was derived using the equivalent electrical resistance calculated from the PM's volume and eddy current density distribution solution. Finally, the resulting current was determined based on analysis of the eddy current loss. The analytical results produced using this application of the space harmonic method were validated extensively through comparison with finite element method results.

  16. Eddy current loss in double-sided cored slotless type permanent magnet linear synchronous generator using analytical method

    Directory of Open Access Journals (Sweden)

    Gang-Hyeon Jang

    2017-05-01

    Full Text Available This paper describes the eddy current loss analysis of a double-sided cored slotless-type permanent magnet linear synchronous generator using the space harmonic method. To calculate the eddy current, an analytical solution was derived by applying the Maxwell equation, magnetic vector potential, and Faraday’s law in a two-dimensional (2-D Cartesian coordinate system. Based on the armature reaction field distribution produced by the armature winding current, we obtained an analytical solution for the eddy current density distribution. Then, an analytical solution for eddy current loss induced in a permanent magnet (PM was derived using the equivalent electrical resistance calculated from the PM’s volume and eddy current density distribution solution. Finally, the resulting current was determined based on analysis of the eddy current loss. The analytical results produced using this application of the space harmonic method were validated extensively through comparison with finite element method results.

  17. Adjoint sensitivity studies of loop current and eddy shedding in the Gulf of Mexico

    KAUST Repository

    Gopalakrishnan, Ganesh

    2013-07-01

    Adjoint model sensitivity analyses were applied for the loop current (LC) and its eddy shedding in the Gulf of Mexico (GoM) using the MIT general circulation model (MITgcm). The circulation in the GoM is mainly driven by the energetic LC and subsequent LC eddy separation. In order to understand which ocean regions and features control the evolution of the LC, including anticyclonic warm-core eddy shedding in the GoM, forward and adjoint sensitivities with respect to previous model state and atmospheric forcing were computed using the MITgcm and its adjoint. Since the validity of the adjoint model sensitivities depends on the capability of the forward model to simulate the real LC system and the eddy shedding processes, a 5 year (2004–2008) forward model simulation was performed for the GoM using realistic atmospheric forcing, initial, and boundary conditions. This forward model simulation was compared to satellite measurements of sea-surface height (SSH) and sea-surface temperature (SST), and observed transport variability. Despite realistic mean state, standard deviations, and LC eddy shedding period, the simulated LC extension shows less variability and more regularity than the observations. However, the model is suitable for studying the LC system and can be utilized for examining the ocean influences leading to a simple, and hopefully generic LC eddy separation in the GoM. The adjoint sensitivities of the LC show influences from the Yucatan Channel (YC) flow and Loop Current Frontal Eddy (LCFE) on both LC extension and eddy separation, as suggested by earlier work. Some of the processes that control LC extension after eddy separation differ from those controlling eddy shedding, but include YC through-flow. The sensitivity remains stable for more than 30 days and moves generally upstream, entering the Caribbean Sea. The sensitivities of the LC for SST generally remain closer to the surface and move at speeds consistent with advection by the high-speed core of

  18. Eddy current analysis and optimization of fast scanning magnet for a proton therapy system

    Science.gov (United States)

    Liu, Xu; Qin, Bin; Liu, Kaifeng; Chen, Wei; Liang, Zhikai; Chen, Qushan; Chen, Dezhi; Fan, Mingwu

    2017-08-01

    Proton therapy is now recognized as one of the most effective radiation therapy methods for cancers. A proton therapy facility with multiple gantry treatment rooms is under development in HUST (Huazhong University of Science and Technology), which is based on isochronous superconducting cyclotron scheme. In the beam line, the scanning system spreads out the proton beam on the target according to the complex tumour shape by two scanning magnets for horizontal and vertical scanning independently. Since these two magnets are excited by alternating currents and the maximum repetition frequency is up to 100 Hz, eddy currents and losses are expected to be significant. Slits are proven to be an effective way to reduce the eddy currents. To evaluate the heat distribution due to eddy losses in the pole end of the scanning magnet, the transient electromagnetic analysis and steady-state thermal analysis are performed. This paper describes design considerations of the scanning system and mainly analyses the eddy current effect of the scanning magnets. Different coil shapes and slit arrangements are simulated and compared to obtain the optimal configuration. The maximum temperatures of two magnets are optimized below 70 °C. In addition, the lag effect due to eddy currents is also discussed.

  19. An application of eddy current damping effect on single point diamond turning of titanium alloys

    Science.gov (United States)

    Yip, W. S.; To, S.

    2017-11-01

    Titanium alloys Ti6Al4V (TC4) have been popularly applied in many industries. They have superior material properties including an excellent strength-to-weight ratio and corrosion resistance. However, they are regarded as difficult to cut materials; serious tool wear, a high level of cutting vibration and low surface integrity are always involved in machining processes especially in ultra-precision machining (UPM). In this paper, a novel hybrid machining technology using an eddy current damping effect is firstly introduced in UPM to suppress machining vibration and improve the machining performance of titanium alloys. A magnetic field was superimposed on samples during single point diamond turning (SPDT) by exposing the samples in between two permanent magnets. When the titanium alloys were rotated within a magnetic field in the SPDT, an eddy current was generated through a stationary magnetic field inside the titanium alloys. An eddy current generated its own magnetic field with the opposite direction of the external magnetic field leading a repulsive force, compensating for the machining vibration induced by the turning process. The experimental results showed a remarkable improvement in cutting force variation, a significant reduction in adhesive tool wear and an extreme long chip formation in comparison to normal SPDT of titanium alloys, suggesting the enhancement of the machinability of titanium alloys using an eddy current damping effect. An eddy current damping effect was firstly introduced in the area of UPM to deliver the results of outstanding machining performance.

  20. An integrated eddy current detection and imaging system on a silicon chip

    Science.gov (United States)

    Henderson, H. Thurman; Kartalia, K. P.; Dury, Joseph D.

    1991-01-01

    Eddy current probes have been used for many years for numerous sensing applications including crack detection in metals. However, these applications have traditionally used the eddy current effect in the form of a physically wound single or different probe pairs which of necessity must be made quite large compared to microelectronics dimensions. Also, the traditional wound probe can only take a point reading, although that point might include tens of individual cracks or crack arrays; thus, conventional eddy current probes are beset by two major problems: (1) no detailed information can be obtained about the crack or crack array; and (2) for applications such as quality assurance, a vast amount of time must be taken to scan a complete surface. Laboratory efforts have been made to fabricate linear arrays of single turn probes in a thick film format on a ceramic substrate as well as in a flexible cable format; however, such efforts inherently suffer from relatively large size requirements as well as sensitivity issues. Preliminary efforts to fully extend eddy current probing from a point or single dimensional level to a two dimensional micro-eddy current format on a silicon chip, which might overcome all of the above problems, are presented.

  1. A numerical study of the acoustic radiation due to eddy current-cryostat interactions.

    Science.gov (United States)

    Wang, Yaohui; Liu, Feng; Zhou, Xiaorong; Li, Yu; Crozier, Stuart

    2017-06-01

    To investigate the acoustic radiation due to eddy current-cryostat interactions and perform a qualitative analysis on noise reduction methods. In order to evaluate the sound pressure level (SPL) of the eddy current induced warm bore wall vibration, a Finite Element (FE) model was created to simulate the noises from both the warm bore wall vibration and the gradient coil assembly. For the SPL reduction of the warm bore wall vibration, we first improved the active shielding of the gradient coil, thus reducing the eddy current on the warm bore wall. A damping treatment was then applied to the warm bore wall to control the acoustic radiation. Initial simulations show that the SPL of the warm bore wall is higher than that of the gradient assembly with typical design shielding ratios at many frequencies. Subsequent simulation results of eddy current control and damping treatment application show that the average SPL reduction of the warm bore wall can be as high as 9.6 dB, and even higher in some frequency bands. Combining eddy current control and suggested damping scheme, the noise level in a MRI system can be effectively reduced. © 2017 American Association of Physicists in Medicine.

  2. Determination of plasma displacement based on eddy current diagnostics for the Keda Torus eXperiment

    Science.gov (United States)

    Tu, Cui; Li, Hong; Liu, Adi; Li, Zichao; Zhang, Yuan; You, Wei; Tan, Mingsheng; Luo, Bing; Adil, Yolbarsop; Hu, Jintong; Wu, Yanqi; Yan, Wentan; Xie, Jinlin; Lan, Tao; Mao, Wenzhe; Ding, Weixing; Xiao, Chijin; Zhuang, Ge; Liu, Wandong

    2017-10-01

    The measurement of plasma displacement is one of the most basic diagnostic tools in the study of plasma equilibrium and control in a toroidal magnetic confinement configuration. During pulse discharge, the eddy current induced in the vacuum vessel and shell will produce an additional magnetic field at the plasma boundary, which will have a significant impact on the measurement of plasma displacement using magnetic probes. In the newly built Keda Torus eXperiment (KTX) reversed field pinch device, the eddy current in the composite shell can be obtained at a high spatial resolution. This device offers a new way to determine the plasma displacement for KTX through the multipole moment expansion of the eddy current, which can be obtained by unique probe arrays installed on the inner and outer surfaces of the composite shell. In an ideal conductor shell approximation, the method of multipole moment expansion of the poloidal eddy current for measuring the plasma displacement in toroidal coordinates, is more accurate than the previous method based on symmetrical magnetic probes, which yielded results in cylindrical coordinates. Through an analytical analysis of many current filaments and numerical simulations of the current distribution in toroidal coordinates, the scaling relation between the first moment of the eddy current and the center of gravity of the plasma current is obtained. In addition, the origin of the multipole moment expansion of the eddy current in KTX is retrieved simultaneously. Preliminary data on the plasma displacement have been collected using these two methods during short pulse discharges in the KTX device, and the results of the two methods are in reasonable agreement.

  3. Characterizing frontal eddies along the East Australian Current from HF radar observations

    Science.gov (United States)

    Schaeffer, Amandine; Gramoulle, A.; Roughan, M.; Mantovanelli, A.

    2017-05-01

    The East Australian Current (EAC) dominates the ocean circulation along south-eastern Australia, however, little is known about the submesoscale frontal instabilities associated with this western boundary current. One year of surface current measurements from HF radars, in conjunction with mooring and satellite observations, highlight the occurrence and propagation of meanders and frontal eddies along the inshore edge of the EAC. Eddies were systematically identified using the geometry of the high spatial resolution (˜1.5 km) surface currents, and tracked every hour. Cyclonic eddies were observed irregularly, on average every 7 days, with inshore radius ˜10 km. Among various forms of structures, frontal eddies associated with EAC meanders were characterized by poleward advection speeds of ˜0.3-0.4 m/s, migrating as far as 500 km south, based on satellite imagery. Flow field kinematics show that cyclonic eddies have high Rossby numbers (0.6-1.9) and enhance particle dispersion. Patches of intensified surface divergence at the leading edge of the structures are expected to generate vertical uplift. This is confirmed by subsurface measurements showing temperature uplift of up to 55 m over 24 h and rough estimates of vertical velocities of 10s of meters per day. While frontal eddies propagate through the radar domain independently of local wind stress, upfront wind can influence their stalling and growth, and can also generate large cold core eddies through intense shear. Such coherent structures are a major mechanism for the transport and entrainment of nutrient rich coastal or deep waters, influencing physical and biological dynamics, and connectivity over large distances.

  4. The early stage wheel fatigue crack detection using eddy current pulsed thermography

    Science.gov (United States)

    Peng, Jianping; Zhang, Kang; Yang, Kai; He, Zhu; Zhang, Yu; Peng, Chaoyong; Gao, Xiaorong

    2017-02-01

    The in-service wheel-set quality is one of critical challenges for railway safety, especially for the high-speed train. The defect in wheel tread, initiated by rolling contact fatigue (RCF) damage, is one of the most significant phenomena and has serious influence on rail industry. Eddy current pulsed thermography is studied to compensate the UT method for detection these early stage of fatigue cracks in wheel tread surface. This paper proposes approximately uniform magnetic field, excited by Helmholtz coils, based pulsed eddy current thermography to achieve open-view image and meet the irregular surface in wheel tread through numerical way. Some features are extracted and studied also to quantify the fatigue crack in term of eddy current pulsed thermography. The proposed method enhances the capability for cracks detection and quantitative evaluation compared with previous NDT method in railway.

  5. Motion-induced eddy current thermography for high-speed inspection

    Directory of Open Access Journals (Sweden)

    Jianbo Wu

    2017-08-01

    Full Text Available This letter proposes a novel motion-induced eddy current based thermography (MIECT for high-speed inspection. In contrast to conventional eddy current thermography (ECT based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday’s law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.

  6. Thickness measuring of electroconductive pipe walls using the dual-frequency eddy-current method

    Science.gov (United States)

    Yakimov, Evgeny; Galtseva, Olga; Ustyugov, Daniil

    2017-01-01

    The paper describes a dual-frequency method for reducing the impact of changes in the gap size between the eddy-current transducer and the pipe, as well as the pipe electrical conductivity on the eddy-current thickness gauge readings. A block-diagram of the dual-frequency eddy-current thickness gauge is proposed for light-alloy drill pipes. The amplitude and signal phase dependencies on the wall thickness in the range from 6 to 17 mm and the gap in the range from 0 to 13.5 mm were studied, the results are presented. The digital signal processing algorithms based on the piecewise-linear approximation of low-frequency and high-frequency signal phase dependencies on the wall thickness are proposed. It is shown that the proposed correction algorithms can reduce the error caused by variations of electrical conductivity and the gap between the transducer and the pipe.

  7. Motion-induced eddy current thermography for high-speed inspection

    Science.gov (United States)

    Wu, Jianbo; Li, Kongjing; Tian, Guiyun; Zhu, Junzhen; Gao, Yunlai; Tang, Chaoqing; Chen, Xiaotian

    2017-08-01

    This letter proposes a novel motion-induced eddy current based thermography (MIECT) for high-speed inspection. In contrast to conventional eddy current thermography (ECT) based on a time-varying magnetic field created by an AC coil, the motion-induced eddy current is induced by the relative motion between magnetic field and inspected objects. A rotating magnetic field created by three-phase windings is used to investigate the heating principle and feasibility of the proposed method. Firstly, based on Faraday's law the distribution of MIEC is investigated, which is then validated by numerical simulation. Further, experimental studies are conducted to validate the proposed method by creating rotating magnetic fields at different speeds from 600 rpm to 6000 rpm, and it is verified that rotating speed will increase MIEC intensity and thereafter improve the heating efficiency. The conclusion can be preliminarily drawn that the proposed MIECT is a platform suitable for high-speed inspection.

  8. Transient Eddy Current Response Due to a Subsurface Crack in a Conductive Plate

    Energy Technology Data Exchange (ETDEWEB)

    Fu, Fangwei [Iowa State Univ., Ames, IA (United States)

    2006-01-01

    Eddy current nondestructive evaluation (NDE) is usually carried out by exciting a time harmonic field using an inductive probe. However, a viable alternative is to use transient eddy current NDE in which a current pulse in a driver coil produces a transient .eld in a conductor that decays at a rate dependent on the conductivity and the permeability of the material and the coil configuration. By using transient eddy current, it is possible to estimate the properties of the conductive medium and to locate and size potential .aws from the measured probe response. The fundamental study described in this dissertation seeks to establish a theoretical understanding of the transient eddy current NDE. Compared with the Fourier transform method, the derived analytical formulations are more convenient when the transient eddy current response within a narrow time range is evaluated. The theoretical analysis provides a valuable tool to study the effect of layer thickness, location of defect, crack opening as well as the optimization of probe design. Analytical expressions have been developed to evaluate the transient response due to eddy currents in a conductive plate based on two asymptotic series. One series converges rapidly for a short time regime and the other for a long time regime and both of them agree with the results calculated by fast Fourier transform over all the times considered. The idea of asymptotic expansion is further applied to determine the induced electromotive force (EMF) in a pick-up coil due to eddy currents in a cylindrical rod. Starting from frequency domain representation, a quasi-static time domain dyadic Green's function for an electric source in a conductive plate has been derived. The resulting expression has three parts; a free space term, multiple image terms and partial reflection terms. The dyadic Green's function serves as the kernel of an electric field integral equation which defines the interaction of an ideal crack with the

  9. Characterization of eddy current distortion effects on magnetic resonance axonography of human brain

    Science.gov (United States)

    Elshafiey, Ibrahim; Narayana, Ponnada A.

    2002-05-01

    Axonography of human brain, based on diffusion tensor magnetic resonance imaging (DT-MRI), has recently gained popularity because of its potential in providing crucial information about intercommunication between different regions of brain. This technique exploits the sensitivity of MRI to random water diffusion in tissues in the presence of diffusion gradient pulses incorporated into the imaging sequence. Large diffusion weighting that is necessary for the generation of axonography with high SNR is achieved by increasing the magnitude of diffusion pulses. However large diffusion gradients induce strong eddy currents in the metallic structure of the cryostat that houses the superconducting coil of the scanner magnet, resulting in distortion of magnetic resonance images. The purpose of this study was to characterize the effect of eddy currents on images obtained using the DT-MRI of human brain. Characterization of eddy current effects is essential for optimizing the scanning parameters and improving image quality. All MRI studies were performed on 1.5-T GE scanner, using single shot diffusion weighed echo planar imaging sequence. All acquisitions were cardiac gated for minimizing the pulsation effect of cerebrospinal fluid (CSF) on the images. Diffusion gradient- or b-space was explored using a set of 62 directions along the two poles, and 60 other directions. Total scan time was less than three minutes. The exploration of the b-space helps quantify the relationship between the orientation of diffusion gradients and eddy current levels. Experimental results demonstrate that certain directions are more prone to eddy current-induced image distortions. Determining the optimum gradient directions should present a powerful technique for reducing eddy current distortion, and thus enhance the use of MRI axonography for a noninvasive assessment of human brain.

  10. Eddy current inspection of tubing; Inspeccion de tubos por corrientes de Foucault

    Energy Technology Data Exchange (ETDEWEB)

    Bauza, J. L. R.; Herrero, J.; Diaz, J.

    1966-07-01

    The Experimental research work carried out to develop a Eddy current testing equipment is described. Search coils with ferrite or air cores were used and the obtained results are discussed. Valuable information was gained from a improved channel in which a direct measure of the defect and the reference signal phase difference is obtained. Artificial defect used to evaluate resolution and sensitivity were produced by electro-machining and mechanical means. Finned SAP tubing was tested in a routine basis with the described equipment and the results plotted. Basic and theoretical considerations on the Eddy current testing technique are given in the last section of this report. (Author)

  11. Tilt-shift eddy current probe impact on information value of response signal

    Directory of Open Access Journals (Sweden)

    Chudacik Vladimir

    2016-03-01

    Full Text Available This article deals with the possibility for increasing of the informational value of a response signal using tilt-shift eddy current probe. Numerical simulations based on the FEM method using the OPERA 3D software as well as gained experimental results are presented. The simulated cracks are evaluated at the selected eddy current probe tilts and shifts with respect to conductive plate to obtain additional data needed for its evaluation and localization. Obtained simulation results are compared and discussed with the experimental results.

  12. Eddy current effects in the magnetization dynamics of ferromagnetic metal nanoparticles

    Science.gov (United States)

    Denisov, S. I.; Lyutyy, T. V.; Pedchenko, B. O.; Babych, H. V.

    2014-07-01

    We develop an analytical model for describing the magnetization dynamics in ferromagnetic metal nanoparticles, which is based on the coupled system of the Landau-Lifshitz-Gilbert (LLG) and Maxwell equations. By solving Maxwell's equations in the quasi-static approximation and finding the magnetic field of eddy currents, we derive the closed LLG equation for the magnetization that fully accounts for the effects of conductivity. We analyze the difference between the LLG equations in metallic and dielectric nanoparticles and show that these effects can strongly influence the magnetization dynamics. As an example illustrating the importance of eddy currents, the phenomenon of precessional switching of magnetization is considered.

  13. Analysis of eddy current loss in Mn-Zn ferrites for power supplies

    Energy Technology Data Exchange (ETDEWEB)

    Yamada, S.; Otsuki, E. [Tokin Corp., Sendai (Japan). Materials Development Lab.

    1995-11-01

    An attempt was made to divide power loss in Mn-Zn ferrites into hysteresis loss, eddy current loss and residual loss factors experimentally. The authors noticed the correspondence between the temperature, Tmin at which hysteresis loss exhibits minimum value, and secondary peak temperature of initial permeability. Analyzing the power loss and electrical resistivity measured at Tmin, it was found that the power loss can be divided into hysteresis loss, resistivity dependent loss component (eddy current loss) and resistivity independent loss component. Consequently, the residual loss was identified to be a loss component independent of resistivity.

  14. Eddy current testing of metallic sheets with defects using force measurements

    Directory of Open Access Journals (Sweden)

    Brauer Hartmut

    2008-01-01

    Full Text Available The problem of determining defects in structures using eddy current methods was investigated. The goal of this work is to demonstrate that the forces generated by the eddy currents and acting back on the magnet system can be used to detect defects in the object. Numerical simulations and experimental investigations have been performed. This novel technique has been found to be sensitive enough to detect even deep defects in an Aluminium bar moving relative to the field-generating magnet system.

  15. Procedure for Automated Eddy Current Crack Detection in Thin Titanium Plates

    Science.gov (United States)

    Wincheski, Russell A.

    2012-01-01

    This procedure provides the detailed instructions for conducting Eddy Current (EC) inspections of thin (5-30 mils) titanium membranes with thickness and material properties typical of the development of Ultra-Lightweight diaphragm Tanks Technology (ULTT). The inspection focuses on the detection of part-through, surface breaking fatigue cracks with depths between approximately 0.002" and 0.007" and aspect ratios (a/c) of 0.2-1.0 using an automated eddy current scanning and image processing technique.

  16. Study on signal processing in Eddy current testing for defects in spline gear

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jae Ho; Park, Tae Sug; Park, Ik Keun [Seoul National University of Science and Technology, Seou (Korea, Republic of)

    2016-06-15

    Eddy current testing (ECT) is commonly applied for the inspection of automated production lines of metallic products, because it has a high inspection speed and a reasonable price. When ECT is applied for the inspection of a metallic object having an uneven target surface, such as the spline gear of a spline shaft, it is difficult to distinguish between the original signal obtained from the sensor and the signal generated by a defect because of the relatively large surface signals having similar frequency distributions. To facilitate the detection of defect signals from the spline gear, implementation of high-order filters is essential, so that the fault signals can be distinguished from the surrounding noise signals, and simultaneously, the pass-band of the filter can be adjusted according to the status of each production line and the object to be inspected. We will examine the infinite impulse filters (IIR filters) available for implementing an advanced filter for ECT, and attempt to detect the flaw signals through optimization of system design parameters for detecting the signals at the system level.

  17. The influence of Loop Current perturbations on the formation and evolution of Tortugas eddies in the southern Straits of Florida

    Science.gov (United States)

    Fratantoni, Paula S.; Lee, Thomas N.; Podesta, Guillermo P.; Muller-Karger, Frank

    1998-10-01

    Large cyclonic eddies on the northern edge of the Florida Current are the dominant mesoscale features within the southern Straits of Florida. The most prominent of these features is a quasi-stationary eddy that forms near the Dry Tortugas. Our observations, compiled from 3 years of advanced very high resolution radiometer measurements in the Straits of Florida and Gulf of Mexico, demonstrate a strong relationship between the generation of anticyclonic rings from the Gulf of Mexico Loop Current and the evolution of Tortugas eddies within the southern Straits of Florida. In six cases, Tortugas eddies evolve from cyclonic frontal eddies which form along the boundary of the Loop Current. The eddies remain stationary near the Dry Tortugas until they are impacted by an approaching Loop Current frontal eddy. The length of time an eddy spends near the Dry Tortugas is increased when the Loop Current sheds an anticyclonic ring. The involvement of a Loop Current frontal eddy in the ring-shedding process results in a delay in its, and hence the Tortugas eddy's, downstream propagation. Results suggest that the lifetime of a Tortugas eddy can be as long as 140 days when a ring-shedding event occurs, or as short as 50 days in the absence of any ring-shedding events. Upon entering the Straits of Florida, the Tortugas eddies are deformed by the narrowing topography and shrink to approximately 55% of their original size as they propagated downstream. The shrinking of these eddies is accompanied by an accelerated translation from 5 km/d in the western Straits of Florida to 16 km/d in the east.

  18. Simulations of the Arctic Boundary Current in an eddy-resolving global ocean model

    Science.gov (United States)

    Aksenov, Y.; Nurser, A. J. G.; Bacon, S.; Coward, A. C.

    2012-04-01

    The Arctic Ocean is shielded from winds by sea ice and is strongly stratified, resulting in extremely low mixing rates. In this quiescent ocean, currents along the continental shelves become the principal dynamical features of the circulation. Observations and model results suggest the existence of a fast oceanic current in the Arctic Ocean, the Arctic Circumpolar Boundary Current (ACBC). The current flows counterclockwise (cyclonically) along the shelf break of the Siberian, Alaskan and Canadian Arctic shelves all way around the Arctic Ocean margins, leaving through western Fram Strait, and taking about two decades to complete the circuit (Aksenov et al., 2011). Simulations with an eddy-resolving global 1/12 degree NEMO model show that the ACBC consists of several jets with the fastest flow occurring at the shelf break. We compare the models results with observations and examine mechanisms driving the ACBC. Through the analysis of the NEMO simulations performed with eddy-resolving, eddy-permitting and non-eddying model configurations we investigate the effect of resolution on the current. Reference Aksenov, Y., V. V. Ivanov, A. J. G. Nurser, S. Bacon, I. V. Polyakov, A. C. Coward, A. C. Naveira-Garabato, and A. Beszczynska-Moeller (2011), The Arctic Circumpolar Boundary Current, J. Geophys. Res., 116, C09017, doi:10.1029/2010JC006637.

  19. Investigation of steel to dielectric transition using microminiature eddy-current converter

    Directory of Open Access Journals (Sweden)

    Malikov Vladimir

    2018-01-01

    Full Text Available The research aims to develop a microminiature converter for electrical steel investigation. The research topic is considered relevant due to the need for evaluation and forecasting of safe operating life of electric steel products. The authors determined the capability to study steel characteristics at different depths based on variations of eddy-current converter amplitude at the steel-dielectric boundary. A microminiature transformer-type converter was designed, which enables to perform local investigations of ferromagnetic materials using eddy-current method based on local studies of the steel electrical conductivity. Having the designed converter as a basis, a hardware-software complex was built to perform experimental studies of steel at the interface boundary. A system was developed for automated converter relocation above the studied object at a specified velocity. Test results are reported for a specimen with continuous and discrete measurements taken at different frequencies. Response dependence of eddy-current converter was found to demonstrate non-linear behavior at steel to dielectric transition. The effect of gap between the eddy-current converter and the test object is investigated.

  20. EDGE EFFECT INFLUENCE TO REFLECTED IMPEDANCE OF EDDY-CURRENT PROBE

    Directory of Open Access Journals (Sweden)

    О. Закревський

    2012-04-01

    Full Text Available This work is dedicated to solve analytically the edge effect Eddy-Current Probe (ECP problem which helpto carry out mathematical research the edge effect influence to ECP precision and sensitivity ultrasonictransducer mechanical amplitude oscillation measurement mathematical research, pointed to cylindricalconductive objects radius control possibility with superimposed ECP.

  1. Eddy Current, Magnetic Particle and Hardness Testing, Aviation Quality Control (Advanced): 9227.04.

    Science.gov (United States)

    Dade County Public Schools, Miami, FL.

    This unit of instruction includes the principles of eddy current, magnetic particle and hardness testing; standards used for analyzing test results; techniques of operating equipment; interpretation of indications; advantages and limitations of these methods of testing; care and calibration of equipment; and safety and work precautions. Motion…

  2. Development of eddy current testing probe for thick-walled metal plate and quantitative evaluation of cracks

    CERN Document Server

    Sato, K; Uchimoto, T; Takagi, T

    2003-01-01

    This paper demonstrates the crack detection of thick-walled non-magnetic metal plates by eddy current testing, which is difficult because of Kelvin skin effect generally. The purpose of this research is the development of an new eddy current testing probe for cracks in thick-walled plates and crack shapes quantitative evaluation. The probe was designed, based on the numerical computation using 3D fast eddy current code. The advantages of this new probe are strong eddy current on the back of specimens and gentle decrement of eddy current in the thickness direction. Through experiments, we confirmed that this probe can detect the back artificial defect with 0.5 mm thickness on IN-CONEL 718 specimen with 7.0 mm thickness. Reconstruction of crack shapes was performed based on the experimental results with the inverse problem code developed by authors. The length and depth of reconstructed defects approximately agree with those of real crack. (author)

  3. Study on characteristics of eddy current array coil operated in transmit-receive mode and surface inspection using this probe

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Tae Hun; Jee, Dong Hyun; Cho, Chan Hee; Kim, In Chul [KHNP Central Research Institute, Daejeon (Korea, Republic of)

    2017-02-15

    Eddy current array (ECA) technology provides the ability to electronically scan without mechanical scanning for a footprint of probe that consists of several eddy current coils arranged side-by-side and two dimensionally. Compared to single-coil eddy current technology, the ECA technology has a higher inspection speed and reliability because a large area can be covered in a single-probe pass and the obtained images can facilitate data interpretation. In this study, we developed an eddy current array probe with 2×16 coil arrays and a multiplexer that can select transmit-receive coils sequentially and operate in transmit-receive mode. Surface inspection was performed using this probe for specimens that had various flaws and the characteristics of transmit-receive mode ECA technology was studied through an analysis of the obtained eddy current signals and C-scan images.

  4. Improved Eddy-current Field Loss Model and Scaling Index for Magnets of Permanent Magnet Synchronous Motors

    Directory of Open Access Journals (Sweden)

    Zhang Lei

    2015-01-01

    Full Text Available The paper gives detailed systematic researches on the mechanism and key factors of eddy-current losses in rotor magnets of high power-density permanent magnet synchronous motors(PMSMs. Firstly, this paper establishes quantitative mathematic model of eddy-current losses for surface-mounted PMSM based on eddy current field model and Maxwell equations. Then, a scaling index is put forward to weigh the key factors relevant to the eddy-current losses in magnets. At the same time, the principles of eddy-current losses in prototype PMSM are analyzed by the finite element analysis (FEA software. The contents researched in the paper have practical reference values for design and reliability analysis of PMSMs.

  5. Oxygen optodes as fast sensors for eddy correlation measurements in aquatic systems

    DEFF Research Database (Denmark)

    Chipman, Lindsay; Huettel, Markus; Berg, Peter

    2012-01-01

    The aquatic eddy-correlation technique can be used to noninvasively determine the oxygen exchange across the sediment-water interface by analyzing the covariance of vertical flow velocity and oxygen concentration in a small measuring volume above the sea bed. The method requires fast sensors...... that can follow the rapid changes in flow and the oxygen transported by this flow to calculate the momentary advective flux driven by turbulent motions. In this article, we demonstrate that fast optical oxygen sensors, known as optodes, represent a good alternative to the traditional Clark......-type electrochemical microelectrodes for such measurements. Optodes have the advantage over microelectrodes of being insensitive to flow, less susceptible to signal drift, more durable under typical field conditions, less expensive, and repairable. Comparisons of the response times of optodes and microelectrodes...

  6. Non destructive technique for cracks detection by an eddy current in differential mode for steel frames

    Science.gov (United States)

    Harzalla, S.; Belgacem, F. Bin Muhammad; Chabaat, M.

    2014-12-01

    In this paper, a nondestructive technique is used as a tool to control cracks and microcracks in materials. A simulation by a numerical approach such as the finite element method is employed to detect cracks and eventually; to study their propagation using a crucial parameter such as the stress intensity factor. This approach has been used in the aircraft industry to control cracks. Besides, it makes it possible to highlight the defects of parts while preserving the integrity of the controlled products. On the other side, it is proven that the reliability of the control of defects gives convincing results for the improvement of the quality and the safety of the material. Eddy current testing (ECT) is a standard technique in industry for the detection of surface breaking flaws in magnetic materials such as steels. In this context, simulation tools can be used to improve the understanding of experimental signals, optimize the design of sensors or evaluate the performance of ECT procedures. CEA-LIST has developed for many years semi-analytical models embedded into the simulation platform CIVA dedicated to non-destructive testing. The developments presented herein address the case of flaws located inside a planar and magnetic medium. Simulation results are obtained through the application of the Volume Integral Method (VIM). When considering the ECT of a single flaw, a system of two differential equations is derived from Maxwell equations. The numerical resolution of the system is carried out using the classical Galerkin variant of the Method of Moments. Besides, a probe response is calculated by application of the Lorentz reciprocity theorem. Finally, the approach itself as well as comparisons between simulation results and measured data are presented.

  7. Reduced Mandated Inspection by Remote Field Eddy Current Inspection of Unpiggable Pipelines

    Energy Technology Data Exchange (ETDEWEB)

    Albert Teitsma; Julie Maupin

    2006-09-29

    The Remote Field Eddy Current (RFEC) technique is ideal for inspecting unpiggable pipelines because all of its components can be made much smaller than the diameter of the pipe to be inspected. For this reason, RFEC was chosen as a technology for unpiggable pipeline inspections by DOE-NETL with the support of OTD and PRCI, to be integrated with platforms selected by DOENETL. As part of the project, the RFEC laboratory facilities were upgraded and data collection was made nearly autonomous. The resulting improved data collection speeds allowed GTI to test more variables to improve the performance of the combined RFEC and platform technologies. Tests were conducted on 6-, 8-, and 12-inch seamless and seam-welded pipes. Testing on the 6-inch pipes included using seven exciter coils, each of different geometry with an initial focus on preparing the technology for use on an autonomous robotic platform with limited battery capacity. Reductions in power consumption proved successful. Tests with metal components similar to the Explorer II modules were performed to check for interference with the electromagnetic fields. The results of these tests indicated RFEC would be able to produce quality inspections while on the robot. Mechanical constraints imposed by the platform, power requirements, control and communication protocols, and potential busses and connectors were addressed. Much work went into sensor module design including the mechanics and electronic diagrams and schematics. GTI participated in two Technology Demonstrations for inspection technologies held at Battelle Laboratories. GTI showed excellent detection and sizing abilities for natural corrosion. Following the demonstration, module building commenced but was stopped when funding reductions did not permit continued development for the selected robotic platform. Conference calls were held between GTI and its sponsors to resolve the issue of how to proceed with reduced funding. The project was rescoped for 10

  8. Energy exchange between the jets of the Antarctic Circumpolar Current and synoptic eddies in the Drake Passage and Scotia Sea

    Science.gov (United States)

    Koshlyakov, Mikhail; Savchenko, Darya; Tarakanov, Roman

    2017-04-01

    Energy exchange between the jets of the Antarctic Circumpolar Current (ACC) and ocean synoptic eddies in the surface layer of the Drake Passage and Scotia Sea is studied on the base of the satellite altimeter data for the period from 1993 to 2014 with the assumption that every ACC jet is enclosed between some fixed isopleths of the ocean surface absolute dynamics topography (ADT). All the ACC jets are dynamically unstable what results in the jet meandering, formation of cyclonic and anticyclonic eddies inside the meanders, intensification of the eddies up to reaching their maximum energy, subsequent eddy attenuation and their reverse merging with the mother jets. Corresponding fluctuations of the kinetic energy of the ACC jets and the eddies, generated by different jets, in the surface ocean layer were computed and analysed for the above mentioned 22 years period. As a main result of the analysis, if was confirmed that the kinetic energy of the ACC jets depends strongly on the intensivity of jet meandering and processes of eddy formation and reverse eddy absorption by the jets. Mean and extreme energy parameters of the jets and eddies were also estimated. The northern and middle jets of the South Polar Current are in the lead with respect to the formation of the ocean synoptic eddies.

  9. On the seasonal variability and eddies in the North Brazil Current: insights from model intercomparison experiments

    Science.gov (United States)

    Barnier, Bernard; Reynaud, Thierry; Beckmann, Aike; Böning, Claus; Molines, Jean-Marc; Barnard, Sally; Jia, Yanli

    The time dependent circulation of the North Brazil Current is studied with three numerical ocean circulation models, which differ by the vertical coordinate used to formulate the primitive equations. The models are driven with the same surface boundary conditions and their horizontal grid-resolution (isotropic, 1/3° at the equator) is in principle fine enough to permit the generation of mesoscale eddies. Our analysis of the mean seasonal currents concludes that the volume transport of the North Brazil Current (NBC) at the equator is principally determined by the strength of the meridional overturning, and suggests that the return path of the global thermohaline circulation is concentrated in the NBC. Models which simulate a realistic overturning at 24°N of the order of 16-18 Sv also simulate a realistic NBC transport of nearly 35 Sv comparable to estimates deduced from the most recent observations. In all models, the major part of this inflow of warm waters from the South Atlantic recirculates in the zonal equatorial current system, but the models also agree on the existence of a permanent coastal mean flow to the north-west, from the equator into the Carribean Sea, in the form of a continuous current or a succession of eddies. Important differences are found between models in their representation of the eddy field. The reasons invoked are the use of different subgrid-scale parameterisations, and differences in stability of the NBC retroflection loop because of differences in the representation of the effect of bottom friction according to the vertical coordinate that is used. Finally, even if differences noticed between models in the details of the seasonal mean circulation and water mass properties could be explained by differences in the eddy field, nonetheless the major characteristics (mean seasonal currents, volume and heat transports) appears to be at first order driven by the strength of the thermohaline circulation.

  10. Eddy-Current Testing of Welded Stainless Steel Storage Containers to Verify Integrity and Identity

    Energy Technology Data Exchange (ETDEWEB)

    Tolk, Keith M.; Stoker, Gerald C.

    1999-07-20

    An eddy-current scanning system is being developed to allow the International Atomic Energy Agency (IAEA) to verify the integrity of nuclear material storage containers. Such a system is necessary to detect attempts to remove material from the containers in facilities where continuous surveillance of the containers is not practical. Initial tests have shown that the eddy-current system is also capable of verifying the identity of each container using the electromagnetic signature of its welds. The DOE-3013 containers proposed for use in some US facilities are made of an austenitic stainless steel alloy, which is nonmagnetic in its normal condition. When the material is cold worked by forming or by local stresses experienced in welding, it loses its austenitic grain structure and its magnetic permeability increases. This change in magnetic permeability can be measured using an eddy-current probe specifically designed for this purpose. Initial tests have shown that variations of magnetic permeability and material conductivity in and around welds can be detected, and form a pattern unique to the container. The changes in conductivity that are present around a mechanically inserted plug can also be detected. Further development of the system is currently underway to adapt the system to verifying the integrity and identity of sealable, tamper-indicating enclosures designed to prevent unauthorized access to measurement equipment used to verify international agreements.

  11. Pulsed eddy-current inspection of thin-walled stainless steel tubing

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, C.V.; Koerner, D.W.; Deeds, W.E.; Pickett, C.A.

    1987-09-01

    A pulsed eddy-current system has been developed for production inspection of small, thin-wall, non-ferromagnetic tubing. To detect and accurately size both outer and bore-side flaws required an operating frequency higher than available from present commercial equipment. A pulsed eddy-current instrument was designed and constructed that used 3.2 MHz square waves, with a bandwidth of 20 MHz. The system is able to reliably detect flaws as small as 0.015 mm (0.6 mils) on either the inner or outer surface of the tube. A computer controls the scanning of the tube, as recording, analyzing, and plotting the data. The computer programs and instrument details are given in the report.

  12. Pulsed Eddy Current Non-destructive Testing and Evaluation: A Review

    Science.gov (United States)

    Sophian, Ali; Tian, Guiyun; Fan, Mengbao

    2017-05-01

    Pulsed eddy current (PEC) non-destructive testing and evaluation (NDT&E) has been around for some time and it is still attracting extensive attention from researchers around the globe, which can be witnessed through the reports reviewed in this paper. Thanks to its richness of spectral components, various applications of this technique have been proposed and reported in the literature covering both structural integrity inspection and material characterization in various industrial sectors. To support its development and for better understanding of the phenomena around the transient induced eddy currents, attempts for its modelling both analytically and numerically have been made by researchers around the world. This review is an attempt to capture the state-of-the-art development and applications of PEC, especially in the last 15 years and it is not intended to be exhaustive. Future challenges and opportunities for PEC NDT&E are also presented.

  13. Brake Performance Analysis of ABS for Eddy Current and Electrohydraulic Hybrid Brake System

    Directory of Open Access Journals (Sweden)

    Ren He

    2013-01-01

    Full Text Available This paper introduces an eddy current and electro-hydraulic hybrid brake system to solve problems such as wear, thermal failure, and slow response of traditional vehicle brake system. Mathematical model was built to calculate the torque of the eddy current brake system and hydraulic brake system and analyze the braking force distribution between two types of brake systems. A fuzzy controller on personal computer based on LabVIEW and Matlab was designed and a set of hardware in the loop system was constructed to validate and analyze the performance of the hybrid brake system. Through lots of experiments on dry and wet asphalt roads, the hybrid brake system achieves perfect performance on the experimental bench, the hybrid system reduces abrasion and temperature of the brake disk, response speed is enhanced obviously, fuzzy controller keeps high utilization coefficient due to the optimal slip ratio regulation, and the total brake time has a smaller decrease than traditional hydraulic brake system.

  14. Coupling method of magnetic memory and eddy current nondestructive testing for retired crankshafts

    Energy Technology Data Exchange (ETDEWEB)

    Ni, Chen; Hua, Lin; Wang, Xiaokai; Wang, Zhou; Qin, Xunpeng; Fang, Zhou [Wuhan University of Technology, Wuhan (Korea, Republic of)

    2016-07-15

    To verify the validity of the Coupling method of magnetic memory and eddy current (CMMEC) testing for crankshafts, we use this technique to test a 12-cylinder V-design diesel crankshaft. First, the stress distribution in the crankshaft was obtained under 12 working conditions using a Finite element (FE) model that complied with the commercial FE code ABAQUS. Second, Magnetic memory testing (MMT) and Eddy current testing (ECT) were adopted to detect the regions of stress concentration in the crankshaft and the specific location of cracks based on simulation results. Lastly, magnetic particle testing was conducted to detect and display the corresponding crack to verify the CMMEC testing results. The MMT and ECT results can provide basis and guidance for the remanufacture and life evaluation of retired crankshafts.

  15. Calculation and Analysis of Permanent Magnet Eddy Current Loss Fault with Magnet Segmentation

    Directory of Open Access Journals (Sweden)

    Bing Li

    2016-01-01

    Full Text Available This paper investigates the problem of calculating and analyzing the effect of the permanent magnet eddy current loss fault due to magnet segmentation. Taking an interior permanent magnet synchronous motor with inverter supplied as an example, the rated power of motor was 2.2 kW. Three-dimensional finite-element model was firstly established based on finite-element software. Then, the model mesh and boundary conditions were handled specially; permanent magnet eddy current loss fault was calculated and analyzed theoretically with magnet segmentation from space harmonic and time harmonic, respectively. Finally, calculation results were compared and explained. A useful conclusion for permanent magnet synchronous motor design has been obtained.

  16. Non-destructive testing of Al-Mg alloys by using the eddy-current method

    Directory of Open Access Journals (Sweden)

    Dmitriev Sergey

    2017-01-01

    Full Text Available The measuring system based on subminiature eddy-current transducers has been developed to carry out local investigations of aluminum-magnesium alloy plates for flaws. The Delianna filter has been modified to allow the significant increase of signal-to-noise ratio. A scheme that uses a computer as a generator and receiver of signals from windings is proposed. It is capable of automatically changing the filtering cutoff frequency and operating frequency of the device. The transducer has been tested on a number of aluminum-magnesium alloy plates with flaws. The article presents data on the relationship of eddy-current transducer response to the presence of flaws in alloys as hidden holes at signal frequencies comprised between 300÷700 Hz on an exciting winding.

  17. Integrodifferential approach to solution of eddy currents in linear structures with motion

    Czech Academy of Sciences Publication Activity Database

    Doležel, Ivo; Karban, P.; Donátová, M.; Šolín, Pavel

    2010-01-01

    Roč. 80, č. 8 (2010), s. 1636-1646 ISSN 0378-4754 R&D Projects: GA ČR(CZ) GA102/07/0496 Institutional research plan: CEZ:AV0Z20570509 Keywords : eddy currents * integrodifferential approach * numerical analysis Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.812, year: 2010 www.elsevier.com/locate/matcom

  18. Eddy Current Transducer Dedicated for Sigma Phase Evaluation in Duplex Stainless Steel

    Directory of Open Access Journals (Sweden)

    Grzegorz Psuj

    2012-01-01

    Full Text Available The paper describes a new transducer dedicated for evaluation of a duplex stainless steel (DSS. Different phases which exist in DSS have influence on mechanical as well as on electrical properties. Therefore, an eddy current transducer was utilized. In order to achieve high sensitivity, a differential type of the transducer was selected. The performance of the transducer was verified by utilizing the samples which had a different amount of sigma phase.

  19. Eddy current effects in the magnetization dynamics of ferromagnetic metal nanoparticles

    OpenAIRE

    Denisov, S. I.; Lyutyy, T. V.; Pedchenko, B. O.; Babych, H. V.

    2014-01-01

    We develop an analytical model for describing the magnetization dynamics in ferromagnetic metal nanoparticles, which is based on the coupled system of the Landau-Lifshitz-Gilbert (LLG) and Maxwell equations. By solving Maxwell's equations in the quasi-static approximation and finding the magnetic field of eddy currents, we derive the closed LLG equation for the magnetization that fully accounts for the effects of conductivity. We analyze the difference between the LLG equations in metallic an...

  20. Assessment of eddy current effects on compression experiments in the TFTR tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Wong, K.L.; Park, W.

    1986-05-01

    The eddy current induced on the TFTR vacuum vessel during compression experiments is estimated based on a cylindrical model. It produces an error magnetic field that generates magnetic islands at the rational magnetic surfaces. The widths of these islands are calculated and found to have some effect on electron energy confinement. However, resistive MHD simulation results indicate that the island formation process can be slowed down by plasma rotation.

  1. Mathematical and numerical models for eddy currents and magnetostatics with selected applications

    CERN Document Server

    Rappaz, Jacques

    2013-01-01

    This monograph addresses fundamental aspects of mathematical modeling and numerical solution methods of electromagnetic problems involving low frequencies, i.e. magnetostatic and eddy current problems which are rarely presented in the applied mathematics literature. In the first part, the authors introduce the mathematical models in a realistic context in view of their use for industrial applications. Several geometric configurations of electric conductors leading to different mathematical models are carefully derived and analyzed, and numerical methods for the solution of the obtained problem

  2. FORTRAN programs for transient eddy current calculations using a perturbation-polynomial expansion technique

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, K.H.

    1976-11-01

    A description is given of FORTRAN programs for transient eddy current calculations in thin, non-magnetic conductors using a perturbation-polynomial expansion technique. Basic equations are presented as well as flow charts for the programs implementing them. The implementation is in two steps--a batch program to produce an intermediate data file and interactive programs to produce graphical output. FORTRAN source listings are included for all program elements, and sample inputs and outputs are given for the major programs.

  3. Multi-element eddy current probe. For inspecting steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Savin, E.; Sartre, B. [FRAMATOME, 92 - Paris-La-Defense (France); Placko, D.; Premel, D. [Ecole Nationale Superieure de Cachan, 94 (France)

    2000-10-01

    Framatome and the Ecole Normale Superieure de Cachan are developing a multi-element eddy current probe for inspecting steam generator tubes of 900 MWe PWR reactors. The device is intended to replace much slower rotating probes. Using its measurements, the conductivity image of any point in the tube can be reconstructed, thanks to a numerical, thanks to a numerical model, thus allowing diagnosis. The first trial results on mockups seem already competitive with those obtained using a rotary probe. (authors)

  4. Application of Eddy Current Techniques for Orbiter Reinforced Carbon-Carbon Structural Health Monitoring

    Science.gov (United States)

    Wincheski, Buzz; Simpson, John

    2005-01-01

    The development and application of advanced nondestructive evaluation techniques for the Reinforced Carbon-Carbon (RCC) components of the Space Shuttle Orbiter Leading Edge Structural Subsystem (LESS) was identified as a crucial step toward returning the shuttle fleet to service. In order to help meet this requirement, eddy current techniques have been developed for application to RCC components. Eddy current technology has been found to be particularly useful for measuring the protective coating thickness over the reinforced carbon-carbon and for the identification of near surface cracking and voids in the RCC matrix. Testing has been performed on as manufactured and flown RCC components with both actual and fabricated defects representing impact and oxidation damage. Encouraging initial results have led to the development of two separate eddy current systems for in-situ RCC inspections in the orbiter processing facility. Each of these systems has undergone blind validation testing on a full scale leading edge panel, and recently transitioned to Kennedy Space Center to be applied as a part of a comprehensive RCC inspection strategy to be performed in the orbiter processing facility after each shuttle flight.

  5. Examination of the junctures of aluminium and dielectric structures using subminiature eddy-current transducers

    Science.gov (United States)

    Dmitriev, S. F.; Malikov, V. N.; Sagalakov, A. M.; Ishkov, A. V.; Katasonov, A. O.

    2017-12-01

    The article presents the structure of a subminiature eddy-current transducer of a transformer type, which is based on the pyramid-shaped core providing the localization of the magnetic field on the area of 2500 μm2. It also describes the major transducer parameters, which provide such localization of the magnetic field. The article describes the structure of the measuring system and the measurement procedure, which allows determining the thickness of different objects depending on the signal. The measuring system includes two subminiaturized eddy-current transducers controlled by software. The output signal of the transducers is processed in the hardware filtration systems. The article contains data demonstrating dependency of the amplitude part of the signal on the different thickness of objects, and states the objects experimentally determined size limits that precondition the practicability of these measurements. Such objects as conductive coatings, laminated structures (metal-polyethylene), solid conductive objects (aluminium) and non-conductive dielectric coatings were examined. The article demonstrates the change of the signal amplitude of the eddy-current transducer depending on the type of the monitored material. The pattern of this change allows determining a type of the studying object and its thickness on a small area of the monitored item.

  6. Analytical modeling and analysis of magnetic field and torque for novel axial flux eddy current couplers with PM excitation

    Science.gov (United States)

    Li, Zhao; Wang, Dazhi; Zheng, Di; Yu, Linxin

    2017-10-01

    Rotational permanent magnet eddy current couplers are promising devices for torque and speed transmission without any mechanical contact. In this study, flux-concentration disk-type permanent magnet eddy current couplers with double conductor rotor are investigated. Given the drawback of the accurate three-dimensional finite element method, this paper proposes a mixed two-dimensional analytical modeling approach. Based on this approach, the closed-form expressions of magnetic field, eddy current, electromagnetic force and torque for such devices are obtained. Finally, a three-dimensional finite element method is employed to validate the analytical results. Besides, a prototype is manufactured and tested for the torque-speed characteristic.

  7. Surface Crack Detection for Carbon Fiber Reinforced Plastic Materials Using Pulsed Eddy Current Based on Rectangular Differential Probe

    Directory of Open Access Journals (Sweden)

    Jialong Wu

    2014-01-01

    Full Text Available Aiming at the surface defect inspection of carbon fiber reinforced composite, the differential and the direct measurement finite element simulation models of pulsed eddy current flaw detection were built. The principle of differential pulsed eddy current detection was analyzed and the sensitivity of defect detection was compared through two kinds of measurements. The validity of simulation results was demonstrated by experiments. The simulation and experimental results show that the pulsed eddy current detection method based on rectangular differential probe can effectively improve the sensitivity of surface defect detection of carbon fiber reinforced composite material.

  8. Measuring currents in a coastal inlet by advection of turbulent eddies in airborne optical imagery

    Science.gov (United States)

    Dugan, J. P.; Piotrowski, C. C.

    2012-03-01

    Water current vector fields in a coastal inlet are retrieved from temporal sequences of optical imagery collected from an aircraft, the velocity being calculated by tracking modulations in the radiance from the surface. The modulations are shown to be consistent with an advecting passive tracer in turbulent flow, leading to the physical mechanism for this signature being turbulent eddies in the flow. The intensity modulations are hypothesized to be light scattered from variations in the sediment load being transported by these turbulent eddies, although other imaging mechanisms such as surface roughness variations may be occurring as well. Supporting evidence is the prevalence of the signature in sediment-laden, nearshore flows along an exposed coast and through a tidal inlet and eddy-like variations in the echo intensity of acoustic Doppler current profilers (ADCPs). Also, the 3-D frequency-wave number spectrum of mapped image sequence data exhibits a classic shape that is consistent with surface turbulence generation by boils and subsequent mixing and advection by eddies in shallow channels. The velocity vector is retrieved by the geometry obtained in the least squares fit of a 2-D planar surface representing advective variance in the 3-D spectrum. These retrievals agree within 15 cm/s root-mean-square (RMS) with concurrent ADCP measurements and within 2 cm/s RMS of measurements of the Doppler shift of surface gravity waves that also are present in the data. The method provides an important new capability for measuring currents over large areas of the littorals, specifically including locations where waves are not present and visible variations in radiance from the water often are not strong.

  9. Observed air-sea interactions in tropical cyclone Isaac over Loop Current mesoscale eddy features

    Science.gov (United States)

    Jaimes, Benjamin; Shay, Lynn K.; Brewster, Jodi K.

    2016-12-01

    Air-sea interactions during the intensification of tropical storm Isaac (2012) into a hurricane, over warm oceanic mesoscale eddy features, are investigated using airborne oceanographic and atmospheric profilers. Understanding these complex interactions is critical to correctly evaluating and predicting storm effects on marine and coastal facilities in the Gulf of Mexico, wind-driven mixing and transport of suspended matter throughout the water column, and oceanic feedbacks on storm intensity. Isaac strengthened as it moved over a Loop Current warm-core eddy (WCE) where sea surface warming (positive feedback mechanism) of ∼0.5 °C was measured over a 12-h interval. Enhanced bulk enthalpy fluxes were estimated during this intensification stage due to an increase in moisture disequilibrium between the ocean and atmosphere. These results support the hypothesis that enhanced buoyant forcing from the ocean is an important intensification mechanism in tropical cyclones over warm oceanic mesoscale eddy features. Larger values in equivalent potential temperature (θE = 365   ∘K) were measured inside the hurricane boundary layer (HBL) over the WCE, where the vertical shear in horizontal currents (δV) remained stable and the ensuing cooling vertical mixing was negligible; smaller values in θE (355   ∘K) were measured over an oceanic frontal cyclone, where vertical mixing and upper-ocean cooling were more intense due to instability development in δV . Thus, correctly representing oceanic mesoscale eddy features in coupled numerical models is important to accurately reproduce oceanic responses to tropical cyclone forcing, as well as the contrasting thermodynamic forcing of the HBL that often causes storm intensity fluctuations over these warm oceanic regimes.

  10. Intelligent MTconnect. Eddy-Current Valve Probe Pilot Project within the High Pressure Gas Facility (HPGF) Liquid Nitrogen Evaporator Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — This project will perform real-time collection of prognostic valve operational data by deploying smart eddy-current probes with the use of the MTconnect® system,...

  11. CHOOSING OF OPERATING FREQUENCY OF EDDY CURRENT THICKNESS METER WITH SUPERIMPOSED TRANSDUCER

    Directory of Open Access Journals (Sweden)

    A. V. Chernyshev

    2014-01-01

    Full Text Available It is shown that when using eddy current thickness meter with superimposed transducer the maximal thickness of the conductive sheets or conductive surface layers of a two-layer wares, which may be controlled with selected frequency of excitation current of the transducer, can be estimated based on the magnitude of the penetration depth of a plane electromagnetic wave in the half-space, the specific electrical conductivity and the relative magnetic permeability of which is equal to the values of these parameters in a controlled surface layer or sheet of two-layer ware.

  12. Southern Ocean overturning across streamlines in an eddying simulation of the Antarctic Circumpolar Current

    Directory of Open Access Journals (Sweden)

    A. M. Treguier

    2007-12-01

    Full Text Available An eddying global model is used to study the characteristics of the Antarctic Circumpolar Current (ACC in a streamline-following framework. Previous model-based estimates of the meridional circulation were calculated using zonal averages: this method leads to a counter-intuitive poleward circulation of the less dense waters, and underestimates the eddy effects. We show that on the contrary, the upper ocean circulation across streamlines agrees with the theoretical view: an equatorward mean flow partially cancelled by a poleward eddy mass flux. Two model simulations, in which the buoyancy forcing above the ACC changes from positive to negative, suggest that the relationship between the residual meridional circulation and the surface buoyancy flux is not as straightforward as assumed by the simplest theoretical models: the sign of the residual circulation cannot be inferred from the surface buoyancy forcing only. Among the other processes that likely play a part in setting the meridional circulation, our model results emphasize the complex three-dimensional structure of the ACC (probably not well accounted for in streamline-averaged, two-dimensional models and the distinct role of temperature and salinity in the definition of the density field. Heat and salt transports by the time-mean flow are important even across time-mean streamlines. Heat and salt are balanced in the ACC, the model drift being small, but the nonlinearity of the equation of state cannot be ignored in the density balance.

  13. Evaluating two numerical advection schemes in HYCOM for eddy-resolving modelling of the Agulhas Current

    Directory of Open Access Journals (Sweden)

    B. C. Backeberg

    2009-06-01

    Full Text Available A 4th order advection scheme is applied in a nested eddy-resolving Hybrid Coordinate Ocean Model (HYCOM of the greater Agulhas Current system for the purpose of testing advanced numerics as a means for improving the model simulation for eventual operational implementation. Model validation techniques comparing sea surface height variations, sea level skewness and variogram analyses to satellite altimetry measurements quantify that generally the 4th order advection scheme improves the realism of the model simulation. The most striking improvement over the standard 2nd order momentum advection scheme, is that the southern Agulhas Current is simulated as a well-defined meandering current, rather than a train of successive eddies. A better vertical structure and stronger poleward transports in the Agulhas Current core contribute toward a better southwestward penetration of the current, and its temperature field, implying a stronger Indo-Atlantic inter-ocean exchange. It is found that the transport, and hence this exchange, is sensitive to the occurrences of mesoscale features originating upstream in the Mozambique Channel and southern East Madagascar Current, and that the improved HYCOM simulation is well suited for further studies of these inter-actions.

  14. Using Eddy Covariance Sensors to Quantify Carbon Metabolism of Peatlands: A Case Study in Turkey

    Directory of Open Access Journals (Sweden)

    Can Ertekin

    2011-01-01

    Full Text Available Net ecosystem exchange (NEE of carbon dioxide (CO2 was measured in a cool temperate peatland in northwestern Turkey on a continuous basis using eddy covariance (EC sensors and multiple (non-linear regression-M(NLR-models. Our results showed that hourly NEE varied between −1.26 and 1.06 mg CO2 m−2 s−1, with a mean value of 0.11 mg CO2 m−2 s−1. Nighttime ecosystem respiration (RE was on average measured as 0.23 ± 0.09 mg CO2 m−2 s−1. Two best-fit M(NLR models estimated daytime RE as 0.64 ± 0.31 and 0.24 ± 0.05 mg CO2 m−2 s−1. Total RE as the sum of nighttime and daytime RE ranged from 0.47 to 0.87 mg CO2 m−2 s−1, thus yielding estimates of gross primary productivity (GPP at −0.35 ± 0.18 and −0.74 ± 0.43 mg CO2 m−2 s−1. Use of EC sensors and M(NLR models is one of the most direct ways to quantify turbulent CO2 exchanges among the soil, vegetation and atmosphere within the atmospheric boundary layer, as well as source and sink behaviors of ecosystems.

  15. Modeling surf zone tracer plumes: 1. Waves, mean currents, and low-frequency eddies

    Science.gov (United States)

    Feddersen, Falk; Clark, David B.; Guza, R. T.

    2011-11-01

    A model that accurately simulates surf zone waves, mean currents, and low-frequency eddies is required to diagnose the mechanisms of surf zone tracer transport and dispersion. In this paper, a wave-resolving time-dependent Boussinesq model is compared with waves and currents observed during five surf zone dye release experiments. In a companion paper, Clark et al. (2011) compare a coupled tracer model to the dye plume observations. The Boussinesq model uses observed bathymetry and incident random, directionally spread waves. For all five releases, the model generally reproduces the observed cross-shore evolution of significant wave height, mean wave angle, bulk directional spread, mean alongshore current, and the frequency-dependent sea surface elevation spectra and directional moments. The largest errors are near the shoreline where the bathymetry is most uncertain. The model also reproduces the observed cross-shore structure of rotational velocities in the infragravity (0.004 surf zone. The model-data agreement for sea swell waves, low-frequency eddies, and mean currents suggests that the model is appropriate for simulating surf zone tracer transport and dispersion.

  16. Eddy Current System for Detection of Cracking Beneath Braiding in Corrugated Metal Hose

    Science.gov (United States)

    Wincheski, Buzz; Simpson, John; Hall, George

    2008-01-01

    In this paper an eddy current system for the detection of partially-through-the-thickness cracks in corrugated metal hose is presented. Design criteria based upon the geometry and conductivity of the part are developed and applied to the fabrication of a prototype inspection system. Experimental data are used to highlight the capabilities of the system and an image processing technique is presented to improve flaw detection capabilities. A case study for detection of cracking damage in a space shuttle radiator retract flex hoses is also presented.

  17. Current Sensor Fault Reconstruction for PMSM Drives

    Directory of Open Access Journals (Sweden)

    Gang Huang

    2016-01-01

    Full Text Available This paper deals with a current sensor fault reconstruction algorithm for the torque closed-loop drive system of an interior PMSM. First, sensor faults are equated to actuator ones by a new introduced state variable. Then, in αβ coordinates, based on the motor model with active flux linkage, a current observer is constructed with a specific sliding mode equivalent control methodology to eliminate the effects of unknown disturbances, and the phase current sensor faults are reconstructed by means of an adaptive method. Finally, an αβ axis current fault processing module is designed based on the reconstructed value. The feasibility and effectiveness of the proposed method are verified by simulation and experimental tests on the RT-LAB platform.

  18. Current Sensor Fault Reconstruction for PMSM Drives.

    Science.gov (United States)

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; He, Jing; Huang, Yi-Shan

    2016-01-30

    This paper deals with a current sensor fault reconstruction algorithm for the torque closed-loop drive system of an interior PMSM. First, sensor faults are equated to actuator ones by a new introduced state variable. Then, in αβ coordinates, based on the motor model with active flux linkage, a current observer is constructed with a specific sliding mode equivalent control methodology to eliminate the effects of unknown disturbances, and the phase current sensor faults are reconstructed by means of an adaptive method. Finally, an αβ axis current fault processing module is designed based on the reconstructed value. The feasibility and effectiveness of the proposed method are verified by simulation and experimental tests on the RT-LAB platform.

  19. Non-contact current and voltage sensor

    Science.gov (United States)

    Carpenter, Gary D; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C; Schappert, Michael A

    2014-03-25

    A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing that contains the current and voltage sensors, which may be a ferrite cylinder with a hall effect sensor disposed in a gap along the circumference to measure current, or alternative a winding provided through the cylinder along its axis and a capacitive plate or wire disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  20. A pivotal role for ocean eddies in the distribution of microbial communities across the Antarctic Circumpolar Current.

    Directory of Open Access Journals (Sweden)

    Siddarthan Venkatachalam

    Full Text Available Mesoscale variability and associated eddy fluxes play crucial roles in ocean circulation dynamics and the ecology of the upper ocean. In doing so, these features are biologically important, providing a mechanism for the mixing and exchange of nutrients and biota within the ocean. Transient mesoscale eddies in the Southern Ocean are known to relocate zooplankton communities across the Antarctic Circumpolar Current (ACC and are important foraging grounds for marine top predators. In this study we investigated the role of cyclonic and anti-cyclonic eddies formed at the South-West Indian Ridge on the spatial variability and diversity of microbial communities. We focused on two contrasting adjacent eddies within the Antarctic Polar Frontal Zone to determine how these features may influence the microbial communities within this region. The water masses and microbiota of the two eddies, representative of a cyclonic cold core from the Antarctic zone and an anti-cyclonic warm-core from the Subantarctic zone, were compared. The data reveal that the two eddies entrain distinct microbial communities from their points of origin that are maintained for up to ten months. Our findings highlight the ecological impact that changes, brought by the translocation of eddies across the ACC, have on microbial diversity.

  1. Discrimination between Fatigue Cracking and Mechanical Damage in Aircraft Fastener Holes by Eddy-Current Phase Rotation

    Science.gov (United States)

    2016-08-01

    Mandache, C., Yanishevsky, M., and Brothers , M., Generic bolt hole eddy current testing probability of detection, LTR-SMPL-2007-0138, National...procedures and phase-analysis based interpretation to reduce false calls,United States Air Force, Wright -Patterson AFB, OH, USA [4] Brausch, J. C...flight structures, AFRL-RX-WP-TR-2008-4373, United States Air Force, Wright -Patterson Air Force Base, OH, USA (2008). [5] Hagemaier, D. J. “Eddy

  2. Total kinetic energy in four global eddying ocean circulation models and over 5000 current meter records

    KAUST Repository

    Scott, Robert B.

    2010-01-01

    We compare the total kinetic energy (TKE) in four global eddying ocean circulation simulations with a global dataset of over 5000, quality controlled, moored current meter records. At individual mooring sites, there was considerable scatter between models and observations that was greater than estimated statistical uncertainty. Averaging over all current meter records in various depth ranges, all four models had mean TKE within a factor of two of observations above 3500. m, and within a factor of three below 3500. m. With the exception of observations between 20 and 100. m, the models tended to straddle the observations. However, individual models had clear biases. The free running (no data assimilation) model biases were largest below 2000. m. Idealized simulations revealed that the parameterized bottom boundary layer tidal currents were not likely the source of the problem, but that reducing quadratic bottom drag coefficient may improve the fit with deep observations. Data assimilation clearly improved the model-observation comparison, especially below 2000. m, despite assimilated data existing mostly above this depth and only south of 47°N. Different diagnostics revealed different aspects of the comparison, though in general the models appeared to be in an eddying-regime with TKE that compared reasonably well with observations. © 2010 Elsevier Ltd.

  3. Modeling of the absolute impedance of coreless coils under eddy-current influence; Modellierung der absoluten Impedanz einer Luftspule mit Wirbelstromrueckwirkung

    Energy Technology Data Exchange (ETDEWEB)

    Wendler, Frank; Troeltzsch, Uwe; Kanoun, Olfa [Technische Univ. Chemnitz (Germany). Lehrstuhl fuer Mess- und Sensortechnik

    2012-07-01

    The analytical modeling of coil impedances is a fundamental task for the design of antennas and eddy current sensors in different application fields. Not only changes of impedance but also the absolute values of the coil impedances are important because they provide a more detailed approach for magnetic material and coil characterization. Magnetic vector potential methods can give an accurate modeling of the magnetic field taking into account eddy current effects. Due to convergence problems during impedance calculation only the change of impedance is obtainable by the magnetic field model itself. These convergence problems can be explained and overcome by applying the concept of the internal and external inductance. In this paper we extent existing analytical impedance modeling techniques from differential impedance models to absolute impedance models. The provided model gives an analytical formula for coil impedances including eddy current influence in the target as well as in the coil itself. With the absolute impedance model available, the maximum of information can be extracted from the measured impedance spectra. The calculated results are compared to experimental values in the frequency range of 10 kHz to 10 MHz. (orig.)

  4. Influence of frontal cyclone evolution on the 2009 (Ekman) and 2010 (Franklin) Loop Current eddy detachment events

    Science.gov (United States)

    Androulidakis, Y. S.; Kourafalou, V. H.; Le Hénaff, M.

    2014-11-01

    The anticyclonic Loop Current Eddy (LCE) shedding events are strongly associated with the evolution of Loop Current Frontal Eddies (LCFEs) over the eastern Gulf of Mexico (GoM). A numerical simulation, in tandem with in situ measurements and satellite data, was used to investigate the Loop Current (LC) evolution and the surrounding LCFE formation, structure, growth and migration during the Eddy Ekman and Eddy Franklin shedding events in the summers of 2009 and 2010, respectively. During both events, northern GoM LCFEs appeared vertically coherent to at least 1500 m in temperature observations. They propagated towards the base of the LC, where, together with the migration of Campeche Bank (southwest GoM shelf) eddies from south of the LC, contributed to its "necking-down". Growth of Campeche Bank LCFEs involved in Eddy Franklin was partially attributed to Campeche Bank waters following upwelling events. Slope processes associated with such upwelling included offshore exports of high positive potential vorticity that may trigger cyclone formation and growth. The advection and growth of LCFEs, originating from the northern and southern GoM, and their interaction with the LC over the LCE detachment area favor shedding conditions and may contribute to the final separation of the LCE.

  5. Influence of frontal cyclones evolution on the 2009 (Ekman) and 2010 (Franklin) Loop Current Eddy detachment events

    Science.gov (United States)

    Androulidakis, Y. S.; Kourafalou, V. H.; Le Hénaff, M.

    2014-07-01

    The anticyclonic Loop Current Eddy (LCE) shedding events are strongly associated with the evolution of Loop Current Frontal Eddies (LCFEs) over the eastern Gulf of Mexico (GoM). A numerical simulation, in tandem with in situ measurements and satellite data, was used to investigate the Loop Current (LC) evolution and the surrounding LCFEs formation, structure, growth and migration during the Eddy Ekman and Eddy Franklin shedding events in the summers of 2009 and 2010, respectively. During both events, Northern GoM LCFEs appeared vertically coherent to at least 1500 m in temperature observations. They propagated towards the base of the LC where, together with the migration of Campeche Bank eddies from south of the LC, contributed to its "necking down". Growth of Campeche Bank LCFEs involved in Eddy Franklin was partially attributed to Campeche Bank waters following upwelling events. Slope processes associated with such upwelling include offshore exports of high positive vorticity that may trigger cyclone formation and growth. The advection and growth of LCFEs, originating from the northern and southern GoM, and their interaction with the LC over the LCE detachment area favor shedding conditions and may lead to the final separation of the LCE.

  6. Current-mode CMOS hybrid image sensor

    Science.gov (United States)

    Benyhesan, Mohammad Kassim

    Digital imaging is growing rapidly making Complimentary Metal-Oxide-Semi conductor (CMOS) image sensor-based cameras indispensable in many modern life devices like cell phones, surveillance devices, personal computers, and tablets. For various purposes wireless portable image systems are widely deployed in many indoor and outdoor places such as hospitals, urban areas, streets, highways, forests, mountains, and towers. However, the increased demand on high-resolution image sensors and improved processing features is expected to increase the power consumption of the CMOS sensor-based camera systems. Increased power consumption translates into a reduced battery life-time. The increased power consumption might not be a problem if there is access to a nearby charging station. On the other hand, the problem arises if the image sensor is located in widely spread areas, unfavorable to human intervention, and difficult to reach. Given the limitation of energy sources available for wireless CMOS image sensor, an energy harvesting technique presents a viable solution to extend the sensor life-time. Energy can be harvested from the sun light or the artificial light surrounding the sensor itself. In this thesis, we propose a current-mode CMOS hybrid image sensor capable of energy harvesting and image capture. The proposed sensor is based on a hybrid pixel that can be programmed to perform the task of an image sensor and the task of a solar cell to harvest energy. The basic idea is to design a pixel that can be configured to exploit its internal photodiode to perform two functions: image sensing and energy harvesting. As a proof of concept a 40 x 40 array of hybrid pixels has been designed and fabricated in a standard 0.5 microm CMOS process. Measurement results show that up to 39 microW of power can be harvested from the array under 130 Klux condition with an energy efficiency of 220 nJ /pixel /frame. The proposed image sensor is a current-mode image sensor which has several

  7. Change of the pulsed eddy Current signals by the variation of the thickness of an aluminum specimen

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Jeong Ki; Shu, Dong Man [Center of Environment and Safty Measurement, Korea Research Institute of Standards and Science, Daejeon (Korea, Republic of); Lee, Seung Seok [R and D Center, RAYNAR Co,. Ltd, Daejeon (Korea, Republic of)

    2004-11-15

    Eddy current testing has been used for detecting the defect like fatigue crack in the conductive materials such as aluminum. The conventional eddy current testing uses a sinusoidal signal with very narrow frequency bandwidth. Whereas, the pulsed eddy current method uses a pulse signal with a broad frequency bandwidth. This allows multi-frequency eddy current testing, and the penetration depth is greater than that of the conventional eddy current testing. In this work, the pulsed eddy current instrument was developed for evaluating the metal loss. The developed instrument was consist of the pulse generator generating the square pulse of maximum 40 V, the amplifier controlled to 52 dB, the A/D converter of 16 bit 20 MHz, and the industrial personal computer for operating with Windows program. And, the probe for the pulsed eddy current was designed as the pancake type in which the sensing coil was located in the driving coil. The peak voltage did not linearly increase with the voltage of the step pulse. For the driving coil with inductance of 670 H, the peak voltage linearly increased with the step pulse voltage to 30 V. But, for the other driving coils with the inductance of 1.7 mH, 2.7 mH, 3.6 mH, 22 mH, the peak voltage linearly increased with the step pulse voltage to 20 V. The output signals of the sensing coil rapidly increased when the step pulse driving voltage was off, and the latter part of the sensing coil output voltage exponentially decreased with a time. The decrement value of tile output signals of sensing coil increased with the thickness of the aluminum test piece.

  8. An innovative experimental sequence on electromagnetic induction and eddy currents based on video analysis and cheap data acquisition

    Science.gov (United States)

    Bonanno, A.; Bozzo, G.; Sapia, P.

    2017-11-01

    In this work, we present a coherent sequence of experiments on electromagnetic (EM) induction and eddy currents, appropriate for university undergraduate students, based on a magnet falling through a drilled aluminum disk. The sequence, leveraging on the didactical interplay between the EM and mechanical aspects of the experiments, allows us to exploit the students’ awareness of mechanics to elicit their comprehension of EM phenomena. The proposed experiments feature two kinds of measurements: (i) kinematic measurements (performed by means of high-speed video analysis) give information on the system’s kinematics and, via appropriate numerical data processing, allow us to get dynamic information, in particular on energy dissipation; (ii) induced electromagnetic field (EMF) measurements (by using a homemade multi-coil sensor connected to a cheap data acquisition system) allow us to quantitatively determine the inductive effects of the moving magnet on its neighborhood. The comparison between experimental results and the predictions from an appropriate theoretical model (of the dissipative coupling between the moving magnet and the conducting disk) offers many educational hints on relevant topics related to EM induction, such as Maxwell’s displacement current, magnetic field flux variation, and the conceptual link between induced EMF and induced currents. Moreover, the didactical activity gives students the opportunity to be trained in video analysis, data acquisition and numerical data processing.

  9. Effects of Coil Diameter in Thickness Measurement Using Pulsed Eddy Current Non-destructive Testing

    Science.gov (United States)

    Nisa Azaman, Khairun; Sophian, Ali; Nafiah, Faris

    2017-11-01

    Non-destructive testing (NDT) techniques are used in industry to evaluate the properties of a material, component or structure without causing any permanent damage. Among the techniques, pulsed eddy current (PEC) NDT is regarded as a new technique where a broadband pulse excitation is used, as opposed to single frequencies employed in conventional eddy current NDT. In this study, a 2D axisymmetric electromagnetic model of a PEC probe has been developed and it has been used to study the effects of the excitation coil diameter on the performance of PEC probes in sample thickness measurement. A PEC system has also been built to validate the model. Aluminium plates are used as the sample and they can be stacked up to replicate thickness from 1 mm to 10 mm. The results show that there is a very good correlation between the simulation and experimental results, with an average error of less than 10%. The results also suggest that the larger the diameter of the excitation coil, the deeper the penetration and therefore the larger the thickness measurement range. It has also been shown that although the larger diameters have deeper penetration, the smallest diameter has the highest sensitivity if normalization is not used. These conclusions indicate that coil diameter is an important parameter in a PEC probe design for thickness measurement applications.

  10. A Novel Application of Eddy Current Braking for Functional Strength Training During Gait.

    Science.gov (United States)

    Washabaugh, Edward P; Claflin, Edward S; Gillespie, R Brent; Krishnan, Chandramouli

    2016-09-01

    Functional strength training is becoming increasingly popular when rehabilitating individuals with neurological injury such as stroke or cerebral palsy. Typically, resistance during walking is provided using cable robots or weights that are secured to the distal shank of the subject. However, there exists no device that is wearable and capable of providing resistance across the joint, allowing over ground gait training. In this study, we created a lightweight and wearable device using eddy current braking to provide resistance to the knee. We then validated the device by having subjects wear it during a walking task through varying resistance levels. Electromyography and kinematics were collected to assess the biomechanical effects of the device on the wearer. We found that eddy current braking provided resistance levels suitable for functional strength training of leg muscles in a package that is both lightweight and wearable. Applying resistive forces at the knee joint during gait resulted in significant increases in muscle activation of many of the muscles tested. A brief period of training also resulted in significant aftereffects once the resistance was removed. These results support the feasibility of the device for functional strength training during gait. Future research is warranted to test the clinical potential of the device in an injured population.

  11. Suppressing local hot spots due to eddy currents in magnetic coil systems

    Science.gov (United States)

    Yao, Zhen; Shojinaga, Aaron; Wu, Yong; Shvartsman, Shmaryu; Eagan, Timothy; Chmielewski, Thomas; Brown, Robert

    2011-03-01

    A particular goal in magnetic field applications is to avoid eddy current heating in coils and shields. It is important, in MRI, for example, to avoid hot spots near the patient to be imaged as well as in the vicinity of soldering joints. We develop effective analytical formulas for the eddy current behavior of sources close to surrounding conductors, we verify these via numerical simulations, and we make successful comparisons to corresponding experimental temperature distributions. Optimized patterns of incisions made in the conductors are discovered for addressing particularly troublesome heating locations. The criteria include the need to minimize the number and length of the cuts. Theory and experiment are in agreement on the efficacy of this method for reducing steady-state temperatures. An example of results in the practical design of commercial coils and shields is that a single cut parallel to the long edge of rectangular conductors reduces the temperatures much more than making multiple cuts parallel to the short edge. Supported by Ohio Third Frontier Program

  12. Characterization of Case Hardened AISI 4130 Steel Using Eddy Current Testing

    Directory of Open Access Journals (Sweden)

    Gukendran R.

    2017-09-01

    Full Text Available Casting is the manufacturing process of pouring the hot liquiduos state metal in to the mold cavity and then allowed it to solidify to obtain the final casting. There are many defects are found in the casting components during the inspection. Some defects are tolerated while others are required to repair. Otherwise the casting component is to be eliminated due to the poor quality level. The aim of the non-destructive inspection is to determine, the flaws, discontinuities on the material, and characteristics of the material. Based on the results by non-destructive evaluation the personnel take the decision on the material object is to be accepted or not as per the criteria. In this paper the hardness attribute of the case hardened AISI 4130 steel samples are studied using Vickers Hardness test. Then the hardness property is correlated with the Eddy Current Testing method. According to the acceptance criterion the suitability of the material is analyzed for the corresponding application or not. In this paper Eddy Current Testing response is analyzed for the AISI 4130 samples to determine the mechanical properties of the material. The main objective of the paper is to investigate the effect of the hardness property of the casting material during various case depth obtained via case hardening process. This technique is effective and best practice for the heat treatment shop floors. By this technique the results are investigated based on the cracks and microstructure of the casting material.

  13. Eddy current testing for blade edge micro cracks of aircraft engine

    Science.gov (United States)

    Zhang, Wei-min; Xu, Min-dong; Gao, Xuan-yi; Jin, Xin; Qin, Feng

    2017-10-01

    Based on the problems of low detection efficiency in the micro cracks detection of aircraft engine blades, a differential excitation eddy current testing system was designed and developed. The function and the working principle of the system were described, the problems which contained the manufacture method of simulated cracks, signal generating, signal processing and the signal display method were described. The detection test was carried out by taking a certain model aircraft engine blade with simulated cracks as a tested specimen. The test data was processed by digital low-pass filter in the computer and the crack signals of time domain display and Lissajous figure display were acquired. By comparing the test results, it is verified that Lissajous figure display shows better performance compared to time domain display when the crack angle is small. The test results show that the eddy current testing system designed in this paper is feasible to detect the micro cracks on the aeroengine blade and can effectively improve the detection efficiency of micro cracks in the practical detection work.

  14. Calibration of eddy current carburization measurements in ethylene production tubes using ion beam analysis

    Energy Technology Data Exchange (ETDEWEB)

    Stevens, K J [Materials Performance Technologies, Industrial Research Ltd, PO Box 31-310, Lower Hutt (New Zealand); Trompetter, W J [Rafter Laboratory, Institute of Geological and Nuclear Sciences, PO Box 31-312, Lower Hutt (New Zealand)

    2004-02-07

    Nuclear reaction analysis using a {sup 12}C(d, p{sub 0}){sup 13}C reaction and a {sup 16}O(d, p{sub 1}){sup 17}O reaction, with 1.02 MeV deuterons in an accelerator microprobe, has been used to produce quantitative linescans of the carbon and oxygen levels in ex-service ethylene pyrolysis tubes of HPM, HK40 and Manaurite XM alloy. Particle induced x-ray emission in the ion beam microprobe and energy dispersive analysis of x-rays in a scanning electron microscope were used for linescans of the heavier elements (Cr, Ni, Fe, Si and Ti). The composition linescans were used to calibrate the response and accuracy of an eddy current probe system for measuring carburization near the inner surface of the tubes. The influence of the ferromagnetic outer oxide surface layers has been clarified. A two-dimensional ANSYS finite element model (FEM) was used for interpretation of the eddy current scans. Good correlation was obtained between the ion beam analysis results, the impedance scans and the FEM.

  15. Calibration of eddy current carburization measurements in ethylene production tubes using ion beam analysis

    Science.gov (United States)

    Stevens, K. J.; Trompetter, W. J.

    2004-02-01

    Nuclear reaction analysis using a 12C(d, p0)13C reaction and a 16O(d, p1)17O reaction, with 1.02 MeV deuterons in an accelerator microprobe, has been used to produce quantitative linescans of the carbon and oxygen levels in ex-service ethylene pyrolysis tubes of HPM, HK40 and Manaurite XM alloy. Particle induced x-ray emission in the ion beam microprobe and energy dispersive analysis of x-rays in a scanning electron microscope were used for linescans of the heavier elements (Cr, Ni, Fe, Si and Ti). The composition linescans were used to calibrate the response and accuracy of an eddy current probe system for measuring carburization near the inner surface of the tubes. The influence of the ferromagnetic outer oxide surface layers has been clarified. A two-dimensional ANSYS finite element model (FEM) was used for interpretation of the eddy current scans. Good correlation was obtained between the ion beam analysis results, the impedance scans and the FEM.

  16. Submesoscale Frontal Vortices and Eddies along the East Australian Current observed by HF Radars

    Science.gov (United States)

    Roughan, M.; Schaeffer, A.; Mantovanelli, A.; Gramoulle, A.

    2016-02-01

    The East Australian Current (EAC) is the major feature of the ocean circulation along south-eastern Australia, influencing the shelf circulation, water temperature, phytoplankton to fish distribution and abundance and the regional climate. While the shedding of mesoscale warm core eddies at the EAC separation of the coast is relatively well understood, little is known about its sub-mesoscale frontal instabilities. More than 1 year of surface currents from HF Radars, in conjunction with mooring measurements, satellite sea surface temperature and ocean color, highlight for the first time the occurrence and propagation of meanders along the inshore edge of the EAC. These instabilities are mostly barotropic and migrate poleward as far as 500 km south, with advection speeds of 0.3 m/s. Investigation into the flow field kinematics shows high Rossby numbers and a strong impact on horizontal divergence and particle dispersion. Wind stress appears to influence the fate of these ageostrophic meanders, their growth and potential evolution into cyclonic cold core eddies. Such coherent structures are a major mechanism for the transport and entrainment of nutrient rich coastal waters, impacting physical and biological connectivity over large distances.

  17. Current Impact Of Fibre Optic Sensors

    Science.gov (United States)

    McGeehin, Peter

    1987-10-01

    Technical and commercial factors important in assessing the impact of fibre optic sensors are considered, and concluded to be of especial importance for the military/aerospace/defence applications areas, Significant growth potential is anticipated, but previous work has not acknowledged the highly fragmented nature of the applications sectors, which are described, The current market for fibre optic sensors is compared with the electro-optics industry in Japan, and applications of electro-optic instrumentation in manufacturing, The work of the UK Optical Sensors Collaborative Association is described as a realistic response for the process/industrial sectors, It is concluded that the technology of fibre optic sensors has not progressed beyond user evaluation of early products, and in spite of the fragmented nature of the industrial and medical areas, growth potential in selected niches shows potential, The technology is particularly strong in the aerospace/defence sector,

  18. Inspection of ferromagnetic support structures from within alloy 800 steam generator tubes using pulsed eddy current

    Science.gov (United States)

    Buck, Jeremy Andrew

    Nondestructive testing is a critical aspect of component lifetime management. Nuclear steam generator (SG) tubes are the thinnest barrier between irradiated primary heat transport system and the secondary heat transport system, whose components are not rated for large radiation fields. Conventional eddy current testing (ECT) and ultrasonic testing are currently employed for inspecting SG tubes, with the former doing most inspections due to speed and reliability based on an understanding of how flaws affect coil impedance parameters when conductors are subjected to harmonically induced currents. However, when multiple degradation modes are present simultaneously near ferromagnetic materials, such as tube fretting, support structure corrosion, and magnetite fouling, ECT reliability decreases. Pulsed eddy current (PEC), which induces transient eddy currents via square wave excitation, has been considered in this thesis to simultaneously examine SG tube and support structure conditions. An array probe consisting of a central driver, coaxial with the tube, and an array of 8 sensing coils, was used in this thesis to perform laboratory measurements. The probe was delivered from the inner diameter (ID) of the SG tube, where support hole diameter, tube frets, and 2D off-centering were varied. When considering two variables simultaneously, scores obtained from a modified principal components analysis (MPCA) were sufficient for parameter extraction. In the case of hole ID variation with two dimensional tube off-centering (three parameters), multiple linear regression (MLR) of the MPCA scores provided good estimates of parameters. However, once a fourth variable, outer diameter tube frets, was introduced, MLR proved insufficient. Artificial neural networks (ANNs) were investigated in order to perform pattern recognition on the MPCA scores to simultaneously extract the four measurement parameters from the data. All models throughout this thesis were created and validated using

  19. Eddy-current inspection of ferromagnetic tubing using pulsed magnetic saturation

    Energy Technology Data Exchange (ETDEWEB)

    Dodd, C V; Deeds, W E

    1986-07-01

    A pulsed eddy-current system has been designed and developed for nondestructive evaluation of 2.25Cr-1Mo steam generator tubing from the bore side. Since the tubing is ferromagnetic, a large current pulse is sent through a driver coil to produce magnetic saturation all the way through the tube wall. A pickup coil produces an output pulse that is dependent upon the tube properties as well as the driving pulse. The output pulse heights at selected times are used as data that are computer-correlated with calibration data taken from machined standards. Performance data, circuit diagrams, and computer programs are given for the system, which has been demonstrated to detect small flaws located near the outside of a thick ferromagnetic tube.

  20. Reduction of eddy current losses around bushing holes on the top-plate of a high efficient transformer

    Directory of Open Access Journals (Sweden)

    Mehmet Aytaç ÇINAR

    2017-08-01

    Full Text Available Low voltage winding leads cause local eddy current losses in top-plate of the transformer tank. In this paper, this loss component which also causes local hot spots is investigated. Top-plate design is modified using stainless steel non-magnetic material, around the low voltage bushing holes. Manufacturing issues and cost as well as power losses are considered as main criteria during modification study. Magnetic flux distributions and eddy current losses are analysed and compared for different designs. Comparisons are based on 3D finite element simulations and experimental studies. Obtained results show that, insertion of single I-shaped stainless steel plate reduces eddy current losses around low voltage bushing holes to nearly zero.

  1. Assessment of Partially Conductive Cracks from Eddy Current Non-Destructive Testing Signals using Support Vector Machine

    Directory of Open Access Journals (Sweden)

    Ladislav Janousek

    2015-01-01

    Full Text Available This paper deals with a three-dimensional non-destructive evaluation of partially conductive cracks from eddy current testing signals. An SUS316L plate specimen containing a crack is non-destructively inspected by the eddy current method using numerical simulations. An extensive database of eddy current response signals is prepared while dimensional parameters of a crack together with its partial conductivity are varied in wide ranges. A Support Vector Machine classification algorithm is employed to solve the electromagnetic inverse problem. The acquired signals are employed for training the algorithm and for testing its performance. It is demonstrated that the Support Vector Machine algorithm is able to properly classify detected defects into proper classes with very high probability even the partial conductivity of a detected crack together with its width are unknown.

  2. Pulsed eddy current inspection of broach support plates in steam generators

    Science.gov (United States)

    Mokros, Sarah Gwendolyn

    Steam Generators (SGs) are a critical component of nuclear reactors, employing thousands of SG tubes to convert heat generated in the reactor core into useable energy. SG tubes are supported at numerous locations by Broach Support Plates (BSPs) that have trefoil shaped holes, which prevent excessive tube vibrations, while allowing water to easily flow through the support structures. A number of degradation modes occur in SGs, such as SG tube fretting, cracking or denting, requiring periodic inspection. Currently, conventional Eddy Current Testing (ECT) is used to non-destructively assess the condition of SG tubes and components. However, as reactors age, new modes of degradation will likely appear that may be difficult to detect and characterize using conventional ECT, such as wall loss in BSPs and build-up of corrosion products, which typically form as a hard sludge called magnetite. Pulsed Eddy Current (PEC) technologies are an emerging technique that is presented in this work as a method to further advance inspection techniques used in CANDURTM nuclear reactors. A PEC probe was designed to inspect the unique shape of the trefoil shaped hole to detect and characterize wall loss and the presence of magnetite in A516 carbon steel BSPs with trefoil shaped holes from within 15.9 mm (5/8") Alloy-800 SG tubes. PEC was also used to observe how measurements of wall loss were affected by the presence of magnetite. This work presents Finite Element Method (FEM) simulations and experimental results collected to observe these degradation modes. The probe was demonstrated to be capable of detecting far side wall loss as low as 20%, locating and characterizing the relative permeability of magnetite, and of detecting wall loss when magnetite was present. FEM simulations and experimental results were found to be in good agreement, suggesting that additional investigations of the effects of BSP degradation on PEC signal response may also be performed using FEM models.

  3. A model of the telluric current eddy: a case from eastern China

    Science.gov (United States)

    Zhang, Xin; Liu, Jun; Du, Xuebin

    2017-06-01

    Electromagnetic induction in the Earth’s interior is an important contributor to the near-Earth geomagnetic and telluric current. The telluric current induced by geomagnetic storms generates secondary geoelectric storms. This motionally induced geoelectric field can be detected in the sea or inland and has potential for electrical soundings of the Earth. This work is aimed at gaining an understanding of the distribution of the current signal due to geomagnetic storms. In this paper, by comparing the geoelectric field during storms and at quiet times, as well as comparing the telluric current calculation results of eastern China and local stations, the following conclusions are obtained. (1) A large range of amplitude change ratios of geoelectric storms is affected by latitude: the amplitude ratio rises at higher latitudes, and the high-frequency composition of geoelectric storms is more complicated than that of geomagnetic storms. (2) The storm creates a large area of electromagnetic fluctuations, and influences the distribution of the telluric current. (3) On the basis of previous studies, a spatial eddy current model is used, which can explain the observation phenomena well. At the same time, a further study direction is put forward on Earth’s electromagnetism.

  4. Dimension Estimation of Rectangular Cracks Using Impedance Changes of the Eddy Current Probe with a Neural Network

    Directory of Open Access Journals (Sweden)

    A. Babaei

    2013-06-01

    Full Text Available In this paper a method for estimating the dimension of rectangular cracks is proposed. The use of Eddy current (ECnondestructive testing (NDT based on probe impedance changes on the crack regions is considered. The artificialneural network estimates the dimension of new cracks using impedance changes of the eddy current probe. Theexperimental results and finite element method (FEM results are used for training the artificial neural network. Byincreasing the number of experiments, the results of the finite element method are not necessary. The simulationresults are very promising.

  5. Sensitivity of Loop Current metrics and eddy detachments to different model configurations : the impact of topography and Caribbean perturbations

    OpenAIRE

    Garcia-Jove, M.; Sheinbaum, J.; Jouanno, Julien

    2016-01-01

    The dynamics of the Loop Current (LC) and the release of its anticyclonic eddy (Loop Current eddy, LCE) are some of the most important features of the circulation in the Gulf of Mexico (GoM) and key aspects to gauge the validity of numerical simulations. Using a numerical model, we investigate the sensitivity of the LC and LCE detachments to three different mechanisms deemed to be relevant to their behavior: a) suppression of Caribbean vorticity perturbations entering the GoM; b) smoothness o...

  6. Computer Calculations of Eddy-Current Power Loss in Rotating Titanium Wheels and Rims in Localized Axial Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Mayhall, D J; Stein, W; Gronberg, J B

    2006-05-15

    We have performed preliminary computer-based, transient, magnetostatic calculations of the eddy-current power loss in rotating titanium-alloy and aluminum wheels and wheel rims in the predominantly axially-directed, steady magnetic fields of two small, solenoidal coils. These calculations have been undertaken to assess the eddy-current power loss in various possible International Linear Collider (ILC) positron target wheels. They have also been done to validate the simulation code module against known results published in the literature. The commercially available software package used in these calculations is the Maxwell 3D, Version 10, Transient Module from the Ansoft Corporation.

  7. An eddy-current model for three-dimensional nondestructive evaluation of advanced composites

    Science.gov (United States)

    Sabbagh, Harold A.; Murphy, R. Kim; Sabbagh, Elias H.

    2015-03-01

    We have developed a rigorous electromagnetic model and an inversion algorithm for the three-dimensional NDE of advanced composite materials. This approach extends Victor Technologies' work in eddy-current NDE of conventional metals, and allows one to determine in localized regions the fiber-resin ratio in graphite-epoxy, and to determine those anomalies, e.g., delaminations, broken fibers, moisture content, etc., that can be reconstructed by our inversion method. In developing the model, we apply rigorous electromagnetic theory to determine a Green's function for a slab of anisotropic composite material, and then determine the integral relations for the forward and inverse problems using the Green's function. We will give examples of the solution of forward problems using this model.

  8. Analytical Modeling Of The Steinmetz Coefficient For Single-Phase Transformer Eddy Current Loss Prediction

    Directory of Open Access Journals (Sweden)

    T. Aly Saandy

    2015-08-01

    Full Text Available Abstract This article presents to an analytical calculation methodology of the Steinmetz coefficient applied to the prediction of Eddy current loss in a single-phase transformer. Based on the electrical circuit theory the active power consumed by the core is expressed analytically in function of the electrical parameters as resistivity and the geometrical dimensions of the core. The proposed modeling approach is established with the duality parallel series. The required coefficient is identified from the empirical Steinmetz data based on the experimented active power expression. To verify the relevance of the model validations both by simulations with two in two different frequencies and measurements were carried out. The obtained results are in good agreement with the theoretical approach and the practical results.

  9. Continuum Modeling of Inductor Hysteresis and Eddy Current Loss Effects in Resonant Circuits

    Energy Technology Data Exchange (ETDEWEB)

    Pries, Jason L. [ORNL; Tang, Lixin [ORNL; Burress, Timothy A. [ORNL

    2017-10-01

    This paper presents experimental validation of a high-fidelity toroid inductor modeling technique. The aim of this research is to accurately model the instantaneous magnetization state and core losses in ferromagnetic materials. Quasi–static hysteresis effects are captured using a Preisach model. Eddy currents are included by coupling the associated quasi-static Everett function to a simple finite element model representing the inductor cross sectional area. The modeling technique is validated against the nonlinear frequency response from two different series RLC resonant circuits using inductors made of electrical steel and soft ferrite. The method is shown to accurately model shifts in resonant frequency and quality factor. The technique also successfully predicts a discontinuity in the frequency response of the ferrite inductor resonant circuit.

  10. Eddy current NDT: a suitable tool to measure oxide layer thickness in PWR fuel rods

    Energy Technology Data Exchange (ETDEWEB)

    Alencar, Donizete A.; Silva Junior, Silverio F. [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)], e-mail: daa@cdtn.br, e-mail: silvasf@cdtn.br; Vieira, Andre L.P.S. [Industrias Nucleares do Brasil (INB S.A.), Resende, RJ (Brazil). Fabrica de Combustivel Nuclear], e-mail: andre@inb.gov.br; Soares, Adolpho [Technotest Consultoria e Acessoria Ltda., Belo Horizonte, MG (Brazil)], e-mail: adolpho@technotest.com.br

    2009-07-01

    Eddy current is a nondestructive test (NDT) widely used in industry to support integrity analysis of components and equipment. In the nuclear area it is frequently applied to inspect tubes installed in tube exchangers, such as steam generators and condensers in PWR plants, as well as turbine blades. Adequately assisted by means of robotic devices, that inspection method has been pointed as a suitable tool to perform accurate oxide layer thickness measurements in PWR fuel rods. This paper shows some theoretical aspects and physical operating principles of the inspection method, as well as test probes construction details, and the calibration reference standards fabrication processes. Furthermore, some data, experimentally obtained at INB laboratories and other technical information obtained from TECNATOM S.A. are presented, showing the accuracy and efficacy of such NDT method. (author)

  11. Nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel and stainless steel alloys

    Energy Technology Data Exchange (ETDEWEB)

    Moore, D.G.; Sorensen, N.R.

    1998-02-01

    This report presents a nondestructive inspection assessment of eddy current and electrochemical analysis to separate inconel alloys from stainless steel alloys as well as an evaluation of cleaning techniques to remove a thermal oxide layer on aircraft exhaust components. The results of this assessment are presented in terms of how effective each technique classifies a known exhaust material. Results indicate that either inspection technique can separate inconel and stainless steel alloys. Based on the experiments conducted, the electrochemical spot test is the optimum for use by airframe and powerplant mechanics. A spot test procedure is proposed for incorporation into the Federal Aviation Administration Advisory Circular 65-9A Airframe & Powerplant Mechanic - General Handbook. 3 refs., 70 figs., 7 tabs.

  12. Reconstruction of semielliptical and epicyclic cracks by eddy-current inversion

    Science.gov (United States)

    Sabbagh, Harold A.; Sabbagh, Elias H.; Kim Murphy, R.

    2002-05-01

    We describe the application of VIC-3D©, a proprietary volume-integral code, to the inversion of benchmark eddy-current data, and the reconstruction of semielliptical and epicyclic cracks. These are modeled as relatively thin surface-breaking slots, whose depth into the workpiece is described by either a semiellipse, or a linear combination of semiellipses. The latter curves, called epicyclic, have a rather complex, double-peaked shape, and are well suited to model a crack with multiple initiation sites. VIC-3Dis used to provide model data for the probe-flaw interaction, which are then fitted to the measured data. The process is quite efficient, and provides accurate reconstructions.

  13. Modelling of eddy-current interaction with cracks in the thin-skin regime. Two approaches

    Energy Technology Data Exchange (ETDEWEB)

    Mastorchio, S. [Electricite de France, 78 - Chatou (France). Research and Development Div.; Harfield, N. [Surrey Univ. (United Kingdom). Dept. of Physics

    1998-02-01

    EDF uses TRIFOU code for eddy current testing modelling. This general electromagnetic code is to be further adapted to Non Destructive Testing applications, not only for nuclear NDT but also in other fields such as aeronautical. This paper compares experimental data for aluminium and steel specimens with two methods of solving the forward problem in the thin-skin regime. The first approach is a 3D Finite Element / Boundary Integral Element method (TRIFOU) developed by EDF/RD Division (France). The second approach is specialized for the treatment of surface cracks in the thin-skin regime developed by the University of Surrey (England). In the thin-skin regime, the electromagnetic skin-depth is small compared with the depth of the crack. Such conditions are common in tests on steels and sometimes on aluminium. (K.A.) 4 refs.

  14. Characterization of Heat Treated Titanium-Based Implants by Nondestructive Eddy Current and Ultrasonic Tests

    Science.gov (United States)

    Mutlu, Ilven; Ekinci, Sinasi; Oktay, Enver

    2014-06-01

    This study presents nondestructive characterization of microstructure and mechanical properties of heat treated Ti, Ti-Cu, and Ti-6Al-4V titanium-based alloys and 17-4 PH stainless steel alloy for biomedical implant applications. Ti, Ti-Cu, and 17-4 PH stainless steel based implants were produced by powder metallurgy. Ti-6Al-4V alloy was investigated as bulk wrought specimens. Effects of sintering temperature, aging, and grain size on mechanical properties were investigated by nondestructive and destructive tests comparatively. Ultrasonic velocity in specimens was measured by using pulse-echo and transmission methods. Electrical conductivity of specimens was determined by eddy current tests. Determination of Young's modulus and strength is important in biomedical implants. Young's modulus of specimens was calculated by using ultrasonic velocities. Calculated Young's modulus values were compared and correlated with experimental values.

  15. A Study of Applying Pulsed Remote Field Eddy Current in Ferromagnetic Pipes Testing.

    Science.gov (United States)

    Luo, Qingwang; Shi, Yibing; Wang, Zhigang; Zhang, Wei; Li, Yanjun

    2017-05-05

    Pulsed Remote Field Eddy Current Testing (PRFECT) attracts the attention in the testing of ferromagnetic pipes because of its continuous spectrum. This paper simulated the practical PRFECT of pipes by using ANSYS software and employed Least Squares Support Vector Regression (LSSVR) to extract the zero-crossing time to analyze the pipe thickness. As a result, a secondary peak is found in zero-crossing time when transmitter passed by a defect. The secondary peak will lead to wrong quantification and the localization of defects, especially when defects are found only at the transmitter location. Aiming to eliminate the secondary peaks, double sensing coils are set in the transition zone and Wiener deconvolution filter is applied. In the proposed method, position dependent response of the differential signals from the double sensing coils is calibrated by employing zero-mean normalization. The methods proposed in this paper are validated by analyzing the simulation signals and can improve the practicality of PRFECT of ferromagnetic pipes.

  16. Evaluation of machine learning tools for inspection of steam generator tube structures using pulsed eddy current

    Science.gov (United States)

    Buck, J. A.; Underhill, P. R.; Morelli, J.; Krause, T. W.

    2017-02-01

    Degradation of nuclear steam generator (SG) tubes and support structures can result in a loss of reactor efficiency. Regular in-service inspection, by conventional eddy current testing (ECT), permits detection of cracks, measurement of wall loss, and identification of other SG tube degradation modes. However, ECT is challenged by overlapping degradation modes such as might occur for SG tube fretting accompanied by tube off-set within a corroding ferromagnetic support structure. Pulsed eddy current (PEC) is an emerging technology examined here for inspection of Alloy-800 SG tubes and associated carbon steel drilled support structures. Support structure hole size was varied to simulate uniform corrosion, while SG tube was off-set relative to hole axis. PEC measurements were performed using a single driver with an 8 pick-up coil configuration in the presence of flat-bottom rectangular frets as an overlapping degradation mode. A modified principal component analysis (MPCA) was performed on the time-voltage data in order to reduce data dimensionality. The MPCA scores were then used to train a support vector machine (SVM) that simultaneously targeted four independent parameters associated with; support structure hole size, tube off-centering in two dimensions and fret depth. The support vector machine was trained, tested, and validated on experimental data. Results were compared with a previously developed artificial neural network (ANN) trained on the same data. Estimates of tube position showed comparable results between the two machine learning tools. However, the ANN produced better estimates of hole inner diameter and fret depth. The better results from ANN analysis was attributed to challenges associated with the SVM when non-constant variance is present in the data.

  17. Transmit-receive eddy current probes for defect detection and sizing in steam generator tubes

    Energy Technology Data Exchange (ETDEWEB)

    Obrutsky, L.S.; Cecco, V.S.; Sullivan, S.P. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    1997-02-01

    Inspection of steam generator tubes in aging Nuclear Generating Stations is increasingly important. Defect detection and sizing, especially in defect prone areas such as the tubesheet, support plates and U-bend regions, are required to assess the fitness-for-service of the steam generators. Information about defect morphology is required to address operational integrity issues, i.e., risk of tube rupture, number of tubes at risk, consequential leakage. A major challenge continues to be the detection and sizing of circumferential cracks. Utilities around the world have experienced this type of tube failure. Conventional in-service inspection, performed with eddy current bobbin probes, is ineffectual in detecting circumferential cracks in tubing. It has been demonstrated in CANDU steam generators, with deformation, magnetite and copper deposits that multi-channel probes with transmit-receive eddy current coils are superior to those using surface impedance coils. Transmit-receive probes have strong directional properties, permitting probe optimization according to crack orientation. They are less sensitive to lift-off noise and magnetite deposits and possess good discrimination to internal defects. A single pass C3 array transmit-receive probe developed by AECL can detect and size circumferential stress corrosion cracks as shallow as 40% through-wall. Since its first trial in 1992, it has been used routinely for steam generator in-service inspection of four CANDU plants, preventing unscheduled shutdowns due to leaking steam generator tubes. More recently, a need has surfaced for simultaneous detection of both circumferential and axial cracks. The C5 probe was designed to address this concern. It combines transmit-receive array probe technology for equal sensitivity to axial and circumferential cracks with a bobbin probe for historical reference. This paper will discuss the operating principles of transmit-receive probes, along with inspection results.

  18. East India Coastal Current induced eddies and their interaction with tropical storms over Bay of Bengal.

    Digital Repository Service at National Institute of Oceanography (India)

    Patnaik, K.V.K.R.K.; Maneesha, K.; Sadhuram, Y.; Prasad, K.V.S.R.; Murty, T.V.R.; Rao, V.B.

    /05/2009) Float ID 2900106 29.24 34 31 35 Warm eddy (13.9N,82.0E) (13/05/2009) Float ID 2901073 30.3 50 135 156 Normal condition (without eddy) (8.6N,84.8E) (28/05/2009) Float... ID 4900670 29.43 28 49 51 14 Table 2 Oceanographic parameters and Enthalphy fluxes in eddies through which the cyclones passed S.No Period/name of the cyclone Central pressure before entering the eddy (hPa) Central pressure...

  19. The Costa Rica Coastal Current, eddies and wind forcing in the Gulf of Tehuantepec, Southern Mexican Pacific

    Science.gov (United States)

    Reyes-Hernández, Cristóbal; Ahumada-Sempoal, Miguel Ángel; Durazo, Reginaldo

    2016-02-01

    The hydrographic structure and circulation of the Southern Mexican Pacific, from August 31 to September 24 2004, when tropical atmospheric activity was at its peak, was analyzed based on AVISO absolute dynamic topography and an array of 106 CTD profiles, within an area of about 500 km×500 km between Punta Maldonado and Puerto Chiapas. The surveyed area was occupied by mesoscale anticyclonic and cyclonic eddies that determined the path of water with temperature and salinity characteristic of the Costa Rica Coastal Current. The origin of each eddy was investigated with respect to QuikSCAT wind conditions. The sequence of AVISO images and wind data showed that the largest anticyclonic eddies originated outside the Gulf of Tehuantepec through mechanisms distinct from local wind forcing, although two northerly wind events in the Gulf of Tehuantepec possibly had an influence on the smallest anticyclonic and cyclonic eddies. The relative position of each eddy allowed the flow of relatively low temperature and salinity water (the Costa Rica Coastal Current) into and throughout the Gulf of Tehuantepec, converging at about Puerto Angel with relatively high temperature and salinity water moving from the west.

  20. Eddy current induced electromagnetic loads on shield blankets during plasma disruptions in ITER: A benchmark exercise

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Duck-Hoi [ITER Korea: National Fusion Research Institute, Gwahangno 113, Yuseong-gu, Daejeon (Korea, Republic of); Oh, Dong-Keun, E-mail: spinhalf@nfri.re.k [ITER Korea: National Fusion Research Institute, Gwahangno 113, Yuseong-gu, Daejeon (Korea, Republic of); Pak, Sunil; Jhang, Hogun [ITER Korea: National Fusion Research Institute, Gwahangno 113, Yuseong-gu, Daejeon (Korea, Republic of); Lee, Jaeyoul [Tae Sung S and E Inc., Yongsan-dong 575, Yuseong-gu, Daejeon (Korea, Republic of); Rozov, Vladimir [ITER Organization, Cadarache, F-13108 St. Paul-lez-Durance (France)

    2010-12-15

    According to recent updates of ITER shield blanket design, electromagnetic loads during the plasma disruption are being evaluated to verify the mechanical confidence and reliability. As a course of such evaluations, a benchmark activity for the electromagnetic analysis, coordinated by ITER Organization, is underway between ITER parties to compare the calculation results for disruption loads on the blankets. In this paper, we present calculation results for the electromagnetic loads on the simplified but practical model of ITER shield blankets with respect to six representative disruption scenarios of which ITER distributes simulation results based on the DINA code as a reference of the design and analysis. Commercial finite element method software, ANSYS/Emag{sup TM}, was employed to evaluate the eddy current on the blanket modules with the 40{sup o} sector model for major conducting structure of the tokamak including double-walled vacuum vessel, triangular support, and vertical targets of divertors. An interface between ANSYS/Emag{sup TM} and plasma simulator was implemented with a conversion tool assigning the plasma current density on the ANSYS elements corresponding to the current filaments in DINA outputs. Discussions are made of the possible improvement of the blanket model taking more realistic blanket configuration into account at the cost of the moderate increase in computational time. A final remark is given of the possibility of incorporating halo currents into ANSYS disruption simulations, which are major sources of electromagnetic loads on in-vessel components including blankets.

  1. Study of a Particle Based Films Cure Process by High-Frequency Eddy Current Spectroscopy

    Directory of Open Access Journals (Sweden)

    Iryna Patsora

    2016-12-01

    Full Text Available Particle-based films are today an important part of various designs and they are implemented in structures as conductive parts, i.e., conductive paste printing in the manufacture of Li-ion batteries, solar cells or resistive paste printing in IC. Recently, particle based films were also implemented in the 3D printing technique, and are particularly important for use in aircraft, wind power, and the automotive industry when incorporated onto the surface of composite structures for protection against damages caused by a lightning strike. A crucial issue for the lightning protection area is to realize films with high homogeneity of electrical resistance where an in-situ noninvasive method has to be elaborated for quality monitoring to avoid undesirable financial and time costs. In this work the drying process of particle based films was investigated by high-frequency eddy current (HFEC spectroscopy in order to work out an automated in-situ quality monitoring method with a focus on the electrical resistance of the films. Different types of particle based films deposited on dielectric and carbon fiber reinforced plastic substrates were investigated in the present study and results show that the HFEC method offers a good opportunity to monitor the overall drying process of particle based films. Based on that, an algorithm was developed, allowing prediction of the final electrical resistance of the particle based films throughout the drying process, and was successfully implemented in a prototype system based on the EddyCus® HFEC device platform presented in this work. This prototype is the first solution for a portable system allowing HFEC measurement on huge and uneven surfaces.

  2. 3D computation of non-linear eddy currents: Variational method and superconducting cubic bulk

    Science.gov (United States)

    Pardo, Enric; Kapolka, Milan

    2017-09-01

    Computing the electric eddy currents in non-linear materials, such as superconductors, is not straightforward. The design of superconducting magnets and power applications needs electromagnetic computer modeling, being in many cases a three-dimensional (3D) problem. Since 3D problems require high computing times, novel time-efficient modeling tools are highly desirable. This article presents a novel computing modeling method based on a variational principle. The self-programmed implementation uses an original minimization method, which divides the sample into sectors. This speeds-up the computations with no loss of accuracy, while enabling efficient parallelization. This method could also be applied to model transients in linear materials or networks of non-linear electrical elements. As example, we analyze the magnetization currents of a cubic superconductor. This 3D situation remains unknown, in spite of the fact that it is often met in material characterization and bulk applications. We found that below the penetration field and in part of the sample, current flux lines are not rectangular and significantly bend in the direction parallel to the applied field. In conclusion, the presented numerical method is able to time-efficiently solve fully 3D situations without loss of accuracy.

  3. Automated correction of unwanted phase jumps in reference signals which corrupt MRSI spectra after eddy current correction.

    NARCIS (Netherlands)

    Simonetti, A.W.; Melssen, W.J.; Graaf, M. van der; Heerschap, A.; Buydens, L.M.C.

    2002-01-01

    A commonly applied step in the postprocessing of gradient localized proton MR spectroscopy, is correction for eddy current effects using the water signal as a reference. However, this method can degrade some of the metabolite signals, in particular if applied on proton MR spectroscopic imaging data.

  4. Correction for Eddy Current-Induced Echo-Shifting Effect in Partial-Fourier Diffusion Tensor Imaging.

    Science.gov (United States)

    Truong, Trong-Kha; Song, Allen W; Chen, Nan-Kuei

    2015-01-01

    In most diffusion tensor imaging (DTI) studies, images are acquired with either a partial-Fourier or a parallel partial-Fourier echo-planar imaging (EPI) sequence, in order to shorten the echo time and increase the signal-to-noise ratio (SNR). However, eddy currents induced by the diffusion-sensitizing gradients can often lead to a shift of the echo in k-space, resulting in three distinct types of artifacts in partial-Fourier DTI. Here, we present an improved DTI acquisition and reconstruction scheme, capable of generating high-quality and high-SNR DTI data without eddy current-induced artifacts. This new scheme consists of three components, respectively, addressing the three distinct types of artifacts. First, a k-space energy-anchored DTI sequence is designed to recover eddy current-induced signal loss (i.e., Type 1 artifact). Second, a multischeme partial-Fourier reconstruction is used to eliminate artificial signal elevation (i.e., Type 2 artifact) associated with the conventional partial-Fourier reconstruction. Third, a signal intensity correction is applied to remove artificial signal modulations due to eddy current-induced erroneous T2(∗) -weighting (i.e., Type 3 artifact). These systematic improvements will greatly increase the consistency and accuracy of DTI measurements, expanding the utility of DTI in translational applications where quantitative robustness is much needed.

  5. Correction for Eddy Current-Induced Echo-Shifting Effect in Partial-Fourier Diffusion Tensor Imaging

    Directory of Open Access Journals (Sweden)

    Trong-Kha Truong

    2015-01-01

    Full Text Available In most diffusion tensor imaging (DTI studies, images are acquired with either a partial-Fourier or a parallel partial-Fourier echo-planar imaging (EPI sequence, in order to shorten the echo time and increase the signal-to-noise ratio (SNR. However, eddy currents induced by the diffusion-sensitizing gradients can often lead to a shift of the echo in k-space, resulting in three distinct types of artifacts in partial-Fourier DTI. Here, we present an improved DTI acquisition and reconstruction scheme, capable of generating high-quality and high-SNR DTI data without eddy current-induced artifacts. This new scheme consists of three components, respectively, addressing the three distinct types of artifacts. First, a k-space energy-anchored DTI sequence is designed to recover eddy current-induced signal loss (i.e., Type 1 artifact. Second, a multischeme partial-Fourier reconstruction is used to eliminate artificial signal elevation (i.e., Type 2 artifact associated with the conventional partial-Fourier reconstruction. Third, a signal intensity correction is applied to remove artificial signal modulations due to eddy current-induced erroneous T2*-weighting (i.e., Type 3 artifact. These systematic improvements will greatly increase the consistency and accuracy of DTI measurements, expanding the utility of DTI in translational applications where quantitative robustness is much needed.

  6. Transformer current sensor for superconducting magnetic coils

    Science.gov (United States)

    Shen, Stewart S.; Wilson, C. Thomas

    1988-01-01

    A transformer current sensor having primary turns carrying a primary current for a superconducting coil and secondary turns only partially arranged within the primary turns. The secondary turns include an active winding disposed within the primary turns and a dummy winding which is not disposed in the primary turns and so does not experience a magnetic field due to a flow of current in the primary turns. The active and dummy windings are wound in opposite directions or connected in series-bucking relationship, and are exposed to the same ambient magnetic field. Voltages which might otherwise develop in the active and dummy windings due to ambient magnetic fields thus cancel out. The resultant voltage is purely indicative of the rate of change of current flowing in the primary turns.

  7. Significant Atmospheric Boundary Layer Change Observed above an Agulhas Current Warm Cored Eddy

    Directory of Open Access Journals (Sweden)

    C. Messager

    2016-01-01

    Full Text Available The air-sea impact of a warm cored eddy ejected from the Agulhas Retroflection region south of Africa was assessed through both ocean and atmospheric profiling measurements during the austral summer. The presence of the eddy causes dramatic atmospheric boundary layer deepening, exceeding what was measured previously over such a feature in the region. This deepening seems mainly due to the turbulent heat flux anomaly above the warm eddy inducing extensive deep and persistent changes in the atmospheric boundary layer thermodynamics. The loss of heat by turbulent processes suggests that this kind of oceanic feature is an important and persistent source of heat for the atmosphere.

  8. Lateral eddy diffusivity estimates from simulated and observed drifter trajectories: a case study for the Agulhas Current system

    Science.gov (United States)

    Rühs, Siren; Zhurbas, Victor; Durgadoo, Jonathan V.; Biastoch, Arne

    2017-04-01

    The Lagrangian description of fluid motion by sets of individual particle trajectories is extensively used to characterize connectivity between distinct oceanic locations. One important factor influencing the connectivity is the average rate of particle dispersal, generally quantified as Lagrangian diffusivity. In addition to Lagrangian observing programs, Lagrangian analyses are performed by advecting particles with the simulated flow field of ocean general circulation models (OGCMs). However, depending on the spatio-temporal model resolution, not all scale-dependent processes are explicitly resolved in the simulated velocity fields. Consequently, the dispersal of advective Lagrangian trajectories has been assumed not to be sufficiently diffusive compared to observed particle spreading. In this study we present a detailed analysis of the spatially variable lateral eddy diffusivity characteristics of advective drifter trajectories simulated with realistically forced OGCMs and compare them with estimates based on observed drifter trajectories. The extended Agulhas Current system around South Africa, known for its intricate mesoscale dynamics, serves as a test case. We show that a state-of-the-art eddy-resolving OGCM indeed features theoretically derived dispersion characteristics for diffusive regimes and realistically represents Lagrangian eddy diffusivity characteristics obtained from observed surface drifter trajectories. The estimates for the maximum and asymptotic lateral single-particle eddy diffusivities obtained from the observed and simulated drifter trajectories show a good agreement in their spatial pattern and magnitude. We further assess the sensitivity of the simulated lateral eddy diffusivity estimates to the temporal and lateral OGCM output resolution and examine the impact of the different eddy diffusivity characteristics on the Lagrangian connectivity between the Indian Ocean and the South Atlantic.

  9. Finite-element analysis of eddy currents in the form-wound multi-conductor windings of electrical machines

    Energy Technology Data Exchange (ETDEWEB)

    Islam, M. J.

    2009-07-01

    The aim of this research was to develop comprehensive numerical models for considering eddy currents and circulating currents in the form-wound multi-conductor windings of electrical machines and to study the effects of eddy currents and circulating currents. Time-harmonic and time-discretised finite-element methods were developed. The methods were applied to the stator winding of a 1250-kW cage induction motor and in both the stator and rotor windings of a 1.7-MW doubly-fed induction generator (DFIG). The series and parallel connections of the winding were taken into account. The Newton-Raphson iteration method was used to solve the system of non-linear equations. In time-harmonic FEM, the system of equations was solved iteratively just once for the steady-state solution. In time-discretised FEM, the system of equations was solved iteratively at every time step. The backward Euler method was used for the time discretisation. The radial distance of the stator bars from the air gap has a remarkable effect on losses and was found to be an important design parameter. A significant amount of stator-winding eddy-current loss can be reduced by considering this design parameter. A transposition of the conductors was implemented to reduce the circulating currents between the parallel stator conductors. The eddy-current effects in the form-wound multi-conductor windings of electrical machines were studied for both a sinusoidal and non-sinusoidal supply. A pulse-width-modulated (PWM) voltage supply was achieved by sinus triangle comparison and used as a non-sinusoidal supply for the machine. A PWM supply produced a significant amount of additional eddy-current losses in the form-wound stator winding of the cage induction motor when compared to the sinusoidal supply. The fundamental harmonic voltages of the sinusoidal and PWM supplies were equal for comparing the results. Similar sinusoidal and PWM voltages were used to supply the rotor winding of the DFIG as well. The

  10. Continued developments in the modeling of complex dimensions and orientation variation in split D differential eddy current probes

    Science.gov (United States)

    Mooers, Ryan D.; Aldrin, John C.

    2017-02-01

    In this paper, model benchmarking for differential eddy current probes is presented, addressing increasing probe complexity including asymmetry, positional, and orientation variations. In prior work, results were presented showing that current models are capable of modeling, with a high degree of accuracy, the variations that come from dimensional, position, and orientation variations; however, one challenge concerned addressing some inherent irregularity and uncertainty in the dimensions of commercial eddy current probes. This current effort addresses these challenges using larger differential coil assembly with coil construction that is more precise and accurate, and through improved model construction and increased mesh resolution. A model validation study is presented that verifies the capability of modeling software to accurately represent probes with varying angle and for different probe designs. Results are also presented highlighting efforts to reduce modeling error observed in prior work in hopes of identifying a metric for how angular variation along the scan direction affects the probe response.

  11. Large Eddy Simulations of Compositional Density Currents Flowing Over a Mobile Bed

    Science.gov (United States)

    Kyrousi, Foteini; Zordan, Jessica; Leonardi, Alessandro; Juez, Carmelo; Zanello, Francesca; Armenio, Vincenzo; Franca, Mário J.

    2017-04-01

    Density currents are a ubiquitous phenomenon caused by natural events or anthropogenic activities, and play an important role in the global sediment cycle; they are agents of long distance sediment transport in lakes, seas and oceans. Density gradients induced by salinity, temperature differences, or by the presence of suspended material are all possible triggers of a current. Such flows can travel long distances while eroding or depositing bed materials. This can provoke rapid topological changes, which makes the estimation of their transport capacity of prime interest for environmental engineering. Despite their relevance, field data regarding their dynamics is limited due to density currents scattered and unpredictable occurrence in nature. For this reason, laboratory experiments and numerical simulations have been a preferred way to investigate sediment transport processes associated to density currents. The study of entrainment and deposition processes requires detailed data of velocities spatial and temporal distributions in the boundary layer and bed shear stress, which are troublesome to obtain in laboratory. Motivated by this, we present 3D wall-resolved Large Eddy Simulations (LES) of density currents generated by lock-exchange. The currents travel over a smooth flat bed, which includes a section composed by erodible fine sediment susceptible of eroding. Several sediment sizes and initial density gradients are considered. The grid is set to resolve the velocity field within the boundary layer of the current (a tiny fraction of the total height), which in turn allows to obtain predictions of the bed shear stress. The numerical outcomes are compared with experimental data obtained with an analogous laboratory setting. In laboratory experiments salinity was chosen for generating the initial density gradient in order to facilitate the identification of entrained particles, since salt does not hinder the possibility to track suspended particles. Under these

  12. Anomalous enhancement of eddy-current anomaly factor in very soft ferromagnetic wires

    Science.gov (United States)

    Li, Y.-F.; Chen, D.-X.; Vazquez, M.

    2004-01-01

    The circular permeability, μ= μ'-j μ″, of two very soft ferromagnetic wires (Co 68.2Fe 4.3Si 12.5B 15 amorphous wire S1 and Fe 73.5Cu 1Nb 3Si 13.5B 9 nanocrystalline wire S2) has been determined from the measurements of the impedance, Z= R+j ωL, as a function of frequency ( f=0.1-100 kHz) and DC bias field ( H=0-89 kA/m). The axial field-dependent DC circular permeability, μDC( H), of two samples exhibit the anomalous enhancement phenomenon as we observed in the similar samples before. The change of the low- f eddy-current anomaly factor, η, with H has been studied. With increasing H from 0 to 3600 A/m, η increase from 1.4 to 8.5 and from 2.8 to 4.2 for samples S1 and S2, respectively, which is contrary to the theoretical expectation that η( H) approaches the value of η=1 with the sample being saturated. This anomalous behavior of η( H) is analyzed in terms of the micro-domain structure resulted from magneto-static interaction between the magnetically hard inclusions and the soft matrix.

  13. Robot-guided eddy current measurement of yarn orientation change during stepwise 3D draping

    Science.gov (United States)

    Bardl, G.; Khan, A. M.; Nocke, A.; Cherif, C.

    2017-10-01

    The production of high-performance carbon fiber-reinforced plastics (CFRP) involves the draping of the carbon fiber fabrics to a 3D shape, a process which changes the orientation of the load-bearing fibers in the fabric and therefore has a high impact on the strength of the final composite part. This paper investigates the change in yarn orientation during the 3D-draping process of biaxial carbon-fiber non-crimp fabrics to a hemispherical shape. The draping process is partitioned in several steps, after each of which the yarn orientation in the fabric is measured by a robot-guided eddy current scanning system. The results show that the greatest change in yarn orientation occurs in the final stages of the draping. Furthermore, the yarn orientation change is not linear – in some regions, later draping steps reverse the yarn orientation change from earlier steps. These results are of high importance for a better controlling of the textile draping process.

  14. Eddy current technology for heat exchanger and steam generator tube inspection

    Energy Technology Data Exchange (ETDEWEB)

    Obrutsky, L.; Lepine, B.; Lu, J.; Cassidy, R.; Carter, J. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2004-07-01

    A variety of degradation modes can affect the integrity of both heat exchanger (HX) and balance of plant tubing, resulting in expensive repairs, tube plugging or replacement of tube bundles. One key component for ensuring tube integrity is inspection and monitoring for detection and characterization of the degradation. In-service inspection of HX and balance of plant tubing is usually carried out using eddy current (EC) bobbin coils, which are adequate for the detection of volumetric degradations. However, detection and quantification of additional modes of degradation such as pitting, intergranular attack (IGA), axial cracking and circumferential cracking require specialized probes. The need for timely, reliable detection and characterization of these modes of degradation is especially critical in Nuclear Generating Stations. Transmit-receive single-pass array probes, developed by AECL, offer high defect detectability in conjunction with fast and reliable inspection capabilities. They have strong directional properties, permitting probe optimization for circumferential or axial crack detection. Compared to impedance probes, they offer improved performance in the presence of variable lift-off. This EC technology can help resolve critical detection issues at susceptible areas, such as the rolled-joint transitions at the tubesheet, U-bends and tube-support intersections. This paper provides an overview of the operating principles and the capabilities of advanced ET inspection technology available for HX tube inspection. Examples of recent application of this technology in Nuclear Generating Stations (NGSs) are discussed. (author)

  15. Approaches to improve separation efficiency of eddy current separation for recovering aluminum from waste toner cartridges.

    Science.gov (United States)

    Ruan, Jujun; Xu, Zhenming

    2012-06-05

    Separation efficiency of eddy current separation (ECS) is low (about 85%) in industrial application for recovering aluminum from crushed waste toner cartridges. Influencing factors of ECS were studied to improve the separation efficiency. Operation factors were researched by orthogonal experiment of ECS on investigating the separation distance between aluminum and plastic flakes. The results indicated the difference (ωR-v) between feeding speed (v) and rotation speed (ω) of magnetic drum (radius: R) was critical factor of influencing the separation efficiency, feeding speed (v) was general factor, and collecting position (H) was subordinate factor. Separation efficiency decreased as the increasing of v, and increased as the increasing of (ωR-v). 0.9 m was the optimal value of H in the orthogonal experiment. Influencing factors of particle characteristics and machine structure were studied by newly established models for computing the separation distance between aluminum and plastic flake in ECS. The results indicated changing of particle size would influence the separation efficiency greater than ω and particle shape. Separation efficiency will increase as the increasing of particle size and ω. Shape of circle is beneficial to improve separation efficiency. Finally, approaches to improve separation efficiency of ECS were presented.

  16. A new model of repulsive force in eddy current separation for recovering waste toner cartridges.

    Science.gov (United States)

    Ruan, Jujun; Xu, Zhenming

    2011-08-15

    Eddy current separation (ECS) is an efficient method for separating aluminum from plastic in crushed waste toner cartridge (TCs). However, in China, ECS quality of aluminum from plastic is rather low in production practice. Repeating separation even manual sorting is required in the production. Improving separation quality of aluminum has been the pressing problem in the recovery of waste TCs. Furthermore, improving ECS quality can reduce the secondary-pollution (furan and dioxin) brought by plastic in later smelting process for the purification of recovered aluminum. Thus, a new model of repulsive force containing impact factors (machine: B(r), k, R, S(m), B(m); material: S(p), V, γ; and operation: ω(m), v, δ) of the separation process was constructed for guiding the ECS process of waste TCs recovering in this paper. For testing whether the model of repulsive force was suitable to guide the ECS, calculation and experiment of detachment angle of aluminum flake were studied. The calculation results of the detachment angles were agreed with the testing experiment. It indicates that the model is suitable for guiding the ECS of waste TCs recovering. Copyright © 2011 Elsevier B.V. All rights reserved.

  17. Construction and assessment of hierarchical edge elements for three-dimensional computations of eddy currents

    Energy Technology Data Exchange (ETDEWEB)

    Midtgaard, Ole-Morten

    1997-12-31

    This thesis considers the feasibility of doing calculations to optimize electrical machines without the need to build expensive prototypes. It deals with the construction and assessment of new, hierarchical, hexahedral edge elements for three-dimensional computations of eddy currents with the electric vector potential formulation. The new elements, five in all, gave up to second-order approximations for both the magnetic field and the current density. Theoretical arguments showed these elements to be more economical for a given polynomial order of the approximated fields than the serendipity family of nodal elements. Further it was pointed out how the support of a source field computed by using edge elements could be made very small provided that a proper spanning tree was used in the edge element mesh. This was exploited for the voltage forcing technique, where source fields were used as basis functions, with unknown total currents in voltage forced conductors as degrees of freedom. The practical assessment of the edge elements proved the accuracy to improve with increasing polynomial order, both for local and global quantities. The most economical element was, however, one giving only complete first-order approximations for both fields. Further, the edge elements turned out to be better than the nodal elements also in practice. For the voltage forcing technique, source field basis functions which had small support, resulted in large reduction of the CPU-time for solving the main equation system, compared to source fields which had large support. The new elements can be used in a p-type adaptive scheme, and they should also be applicable for other tangentially continuous field problems. 67 refs., 34 figs., 10 tabs.

  18. Temperature compensated current sensor using reference magnetic field

    Science.gov (United States)

    Yakymyshyn, Christopher Paul; Brubaker, Michael Allen; Yakymyshyn, Pamela Jane

    2007-10-09

    A method is described to provide temperature compensation and self-calibration of a current sensor based on a plurality of magnetic field sensors positioned around a current carrying conductor. A reference magnetic field generated within the current sensor housing is detected by a separate but identical magnetic field sensor and is used to correct variations in the output signal due to temperature variations and aging.

  19. A Bayesian Network Method for Quantitative Evaluation of Defects in Multilayered Structures from Eddy Current NDT Signals

    Directory of Open Access Journals (Sweden)

    Bo Ye

    2014-01-01

    Full Text Available Accurate evaluation and characterization of defects in multilayered structures from eddy current nondestructive testing (NDT signals are a difficult inverse problem. There is scope for improving the current methods used for solving the inverse problem by incorporating information of uncertainty in the inspection process. Here, we propose to evaluate defects quantitatively from eddy current NDT signals using Bayesian networks (BNs. BNs are a useful method in handling uncertainty in the inspection process, eventually leading to the more accurate results. The domain knowledge and the experimental data are used to generate the BN models. The models are applied to predict the signals corresponding to different defect characteristic parameters or to estimate defect characteristic parameters from eddy current signals in real time. Finally, the estimation results are analyzed. Compared to the least squares regression method, BNs are more robust with higher accuracy and have the advantage of being a bidirectional inferential mechanism. This approach allows results to be obtained in the form of full marginal conditional probability distributions, providing more information on the defect. The feasibility of BNs presented and discussed in this paper has been validated.

  20. Research of aluminum alloys with using eddy-current transducers on the basis of cores of various form

    Science.gov (United States)

    Dmitriev, S. F.; Ishkov, A. V.; Katasonov, A. O.; Malikov, V. N.; Sagalakov, A. M.

    2018-01-01

    The research aims to develop a microminiature eddy current transducer for aluminum alloys. The research topic is considered relevant due to the need for evaluation and forecasting of safe operating life of aluminum. A microminiature transformer-type transducer was designed, which enables to perform local investigations of unferromagnetic materials using eddy-current method based on local studies conductivity. Having the designed transducer as a basis, a hardware-software complex was built to perform experimental studies of aluminium. Cores with different shapes were used in this work. Test results are reported for a flaws in the form of hidden slits and apertures inside the slabs is derived for excitation coil frequencies of 300–700 Hz.

  1. Temperature compensated and self-calibrated current sensor

    Science.gov (United States)

    Yakymyshyn, Christopher Paul; Brubaker, Michael Allen; Yakymyshyn, Pamela Jane

    2007-09-25

    A method is described to provide temperature compensation and reduction of drift due to aging for a current sensor based on a plurality of magnetic field sensors positioned around a current carrying conductor. The offset voltage signal generated by each magnetic field sensor is used to correct variations in the output signal due to temperature variations and aging.

  2. Three-dimensional finite element computation of a remote field eddy current technique to non-magnetic tubes

    OpenAIRE

    福冨, 広幸; 高木, 敏行; 谷, 順二; 西川, 雅弘; Hiroyuki, FUKUTOMI; Toshiyuki, TAKAGI; Junji, TANI; Masahiro, NISHIKAWA; 東北大学; 東北大学; 東北大学; 大阪大学

    1998-01-01

    The remote field eddy current technique(RFECT) is a well established through-wall inspection method that detects external and internal wall losses with approximately equal sensitivity. Its applications have been primarily in the inspection of ferromagnetic tubes. Conventional ECT is restricted to measure cracks on the outer surfaces of tubes by the nature of skin effect. In the in-service inspection of steam generator tubes in pressurized water reactor-type nuclear plants, for example, it is ...

  3. ORIENTED FOR CAD UNIVERSAL MATHEMATICAL MODEL OF THE EDDY CURRENT PROBE. PART 1. THE RESULTING FIELD OF THE DRIVE WINDING

    Directory of Open Access Journals (Sweden)

    A. G. Dedegkaev

    2015-01-01

    Full Text Available The work relates to the field of CAD methods and means of nondestructive electromagnetic testing of conductive flat products. The problem of constructing mathematical model of the drive winding eddy current probe linearly extended form is polygon in cross section. This allows you to create a universal mathematical model, which includes a model of a simpler shape in cross-section, as a special case. 

  4. Eddy heat flux across the Antarctic Circumpolar Current estimated from sea surface height standard deviation

    Science.gov (United States)

    Foppert, Annie; Donohue, Kathleen A.; Watts, D. Randolph; Tracey, Karen L.

    2017-08-01

    Eddy heat flux (EHF) is a predominant mechanism for heat transport across the zonally unbounded mean flow of the Antarctic Circumpolar Current (ACC). Observations of dynamically relevant, divergent, 4 year mean EHF in Drake Passage from the cDrake project, as well as previous studies of atmospheric and oceanic storm tracks, motivates the use of sea surface height (SSH) standard deviation, H*, as a proxy for depth-integrated, downgradient, time-mean EHF (>[EHF>¯>]) in the ACC. Statistics from the Southern Ocean State Estimate corroborate this choice and validate throughout the ACC the spatial agreement between H* and >[EHF>¯>] seen locally in Drake Passage. Eight regions of elevated >[EHF>¯>] are identified from nearly 23.5 years of satellite altimetry data. Elevated cross-front exchange usually does not span the full latitudinal width of the ACC in each region, implying a hand-off of heat between ACC fronts and frontal zones as they encounter the different >[EHF>¯>] hot spots along their circumpolar path. Integrated along circumpolar streamlines, defined by mean SSH contours, there is a convergence of ∮>[EHF>¯>] in the ACC: 1.06 PW enters from the north and 0.02 PW exits to the south. Temporal trends in low-frequency [EHF] are calculated in a running-mean sense using H* from overlapping 4 year subsets of SSH. Significant increases in downgradient [EHF] magnitude have occurred since 1993 at Kerguelen Plateau, Southeast Indian Ridge, and the Brazil-Malvinas Confluence, whereas the other five >[EHF>¯>] hot spots have insignificant trends of varying sign.

  5. Temperature compensated and self-calibrated current sensor using reference current

    Science.gov (United States)

    Yakymyshyn, Christopher Paul [Seminole, FL; Brubaker, Michael Allen [Loveland, CO; Yakymyshyn, Pamela Jane [Seminole, FL

    2008-01-22

    A method is described to provide temperature compensation and self-calibration of a current sensor based on a plurality of magnetic field sensors positioned around a current carrying conductor. A reference electrical current carried by a conductor positioned within the sensing window of the current sensor is used to correct variations in the output signal due to temperature variations and aging.

  6. Evaluation of Stress Anisotropy and Shearing Stress Using an Eddy Current Method with a Tangential-Rectangular Coil

    Science.gov (United States)

    Sekine, Yuichi; Soyama, Hitoshi

    In establishing a system to evaluate residual stress, it is important to design the system so that it can also evaluate the stress anisotropy, since this is introduced into metallic materials by surface processes such as grinding and polishing. The shearing stress is also an important parameter when the shear strength has to be considered, since tensile stress can cause stress corrosion cracking. Thus, a method to nondestructively evaluate the stress anisotropy and shearing stress in a short time is required. In this paper, a nondestructive eddy current method using a tangential-rectangular coil was used to accomplish this. The material under test was stainless steel, Japanese Industrial Standard (JIS) SUS316L, ground or polished by an angle grinder. The stress anisotropy caused by the grinding and polishing processes was evaluated by the eddy current method with the tangential-rectangular coil. To vary the stress state, some specimens were treated with cavitation peening after grinding with the angle grinder. The results demonstrate that the stress anisotropy, shearing stress and peening intensity can be evaluated by the eddy current method using the tangential-rectangular coil. From the results, it was concluded that the maximum shearing stress and the direction of the principal stress could be determined.

  7. Development of Eddy Current Technique for the Detection of Stress Corrosion Cracking in Space Shuttle Primary Reaction Control Thrusters

    Science.gov (United States)

    Wincheski, Buzz; Simpson, John; Koshti, Ajay

    2006-01-01

    A recent identification of stress corrosion cracking in the Space Shuttle Primary Reaction Control System (PRCS) thrusters triggered an extensive nondestructive evaluation effort to develop techniques capable of identifying such damage on installed shuttle hardware. As a part of this effort, specially designed eddy current probes inserted into the acoustic cavity were explored for the detection of such flaws and for evaluation of the remaining material between the crack tip and acoustic cavity. The technique utilizes two orthogonal eddy current probes which are scanned under stepper motor control in the acoustic cavity to identify cracks hidden with as much as 0.060 remaining wall thickness to the cavity. As crack growth rates in this area have been determined to be very slow, such an inspection provides a large safety margin for continued operation of the critical shuttle hardware. Testing has been performed on thruster components with both actual and fabricated defects. This paper will review the design and performance of the developed eddy current inspection system. Detection of flaws as a function of remaining wall thickness will be presented along with the proposed system configuration for depot level or on-vehicle inspection capabilities.

  8. Analysis of Eddy Current Capabilities for the Detection of Outer Diameter Stress Corrosion Cracking in Small Bore Metallic Structures

    Science.gov (United States)

    Wincheski, Buzz; Williams, Phillip; Simpson, John

    2007-01-01

    The use of eddy current techniques for the detection of outer diameter damage in tubing and many complex aerospace structures often requires the use of an inner diameter probe due to a lack of access to the outside of the part. In small bore structures the probe size and orientation are constrained by the inner diameter of the part, complicating the optimization of the inspection technique. Detection of flaws through a significant remaining wall thickness becomes limited not only by the standard depth of penetration, but also geometrical aspects of the probe. Recently, an orthogonal eddy current probe was developed for detection of such flaws in Space Shuttle Primary Reaction Control System (PRCS) Thrusters. In this case, the detection of deeply buried stress corrosion cracking by an inner diameter eddy current probe was sought. Probe optimization was performed based upon the limiting spatial dimensions, flaw orientation, and required detection sensitivity. Analysis of the probe/flaw interaction was performed through the use of finite and boundary element modeling techniques. Experimental data for the flaw detection capabilities, including a probability of detection study, will be presented along with the simulation data. The results of this work have led to the successful deployment of an inspection system for the detection of stress corrosion cracking in Space Shuttle Primary Reaction Control System (PRCS) Thrusters.

  9. Earth's gravity gradient and eddy currents effects on the rotational dynamics of space debris objects: Envisat case study

    Science.gov (United States)

    Gómez, Natalia Ortiz; Walker, Scott J. I.

    2015-08-01

    The space debris population has grown rapidly over the last few decades with the consequent growth of impact risk between current objects in orbit. Active Debris Removal (ADR) has been recommended to be put into practice by several National Agencies in order to remove objects that pose the biggest risk for the space community. The most immediate target that is being considered for ADR by the European Space Agency is the Earth-observing satellite Envisat. In order to safely remove such a massive object from its orbit, a capturing process followed by a controlled reentry is necessary. However, current ADR methods that require physical contact with the target have limitations on the maximum angular momentum that can be absorbed and a de-tumbling phase prior to the capturing process may be required. Therefore, it is of utmost importance for the ADR mission design to be able to predict accurately how the target will be rotating at the time of capture. This article analyses two perturbations that affect an object in Low Earth Orbit (LEO), the Earth's gravity gradient and the eddy currents induced by the Earth's magnetic field. The gravity gradient is analysed using the equation of conservation of total energy and a graphical method is presented to understand the expected behaviour of any object under the effect of this perturbation. The eddy currents are also analysed by studying the total energy of the system. The induced torque and the characteristic time of decay are presented as a function of the object's magnetic tensor. In addition, simulations were carried out for the Envisat spacecraft including the gravity gradient perturbation as well as the eddy currents effect using the International Geomagnetic Reference Field IGRF-11 to model the Earth's magnetic field. These simulations show that the combined effect of these two perturbations is a plausible explanation for the rotational speed decay observed between April 2013 and September 2013.

  10. Wavelets transforms and fuzzy logic in the eddy-current inspection of nuclear power plants steam generator tubes; Transformadas de wavelets e logica fuzzy na inspecao por eddy-current em tubos de geradores de vapor de centrais nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Luiz Antonio Negro Martin

    2002-07-01

    Nuclear power plants steam generators around the world have presented early damage history in their tubes, caused either by design errors or by inappropriate operation, which besides reducing the availability and the safety of the nuclear power plants it also generates heavy economical burden. To monitor the steam generators operational condition, the Eddy Current testing of their tubes is the non destructive method used to detect, localize, classify and to size the defects. The inspection is performed by inserting probes with coils in the tubes generating a signal correlated to the defect. These signals produced by the probe electric circuit are composed by the resistance and the inductive components which can be combined to produce a Lissajous figure in the complex plane. However, Eddy-Current signals contain noise which induce subjectivity inducing to errors in the inspector diagnosis. It is not uncommon to have different diagnosis from two inspectors about the same signal. The present work has the objective of supplying a methodology to analyze the signals which could help the inspector in the difficult task of interpreting the Eddy Current signals. It is proposed a method to remove the noise based on Wavelets Transforms. It is also proposed a normalization in the signal phase angle measurements. Furthermore, two additional characteristics are also studied, namely: the signal amplitudes and the widths of the Lissajous petals. The use of a Fuzzy Logic based inference engine is also developed and its use is demonstrated to be viable. The defects studied in this work are those which produces volumetric changes in the material. In order to test the proposed methodology, several artificial defects were produced in tubes using different types of materials like: brass, 316L stainless steel and Inconel 600 to produce a experimental data base. An Eddy-Current inspection equipment, the MIZ-17ET was used. Around 1000 time series signals of defects were acquired through

  11. Eddy current effects in plain and hollow cylinders spinning inside homogeneous magnetic fields: application to magnetic resonance.

    Science.gov (United States)

    Aubert, G; Jacquinot, J-F; Sakellariou, D

    2012-10-21

    We present a thorough analysis of eddy currents that develop in a rectangular cross section toroid rotating in a uniform magnetic field. The slow rotation regime is assumed. Compact expressions for the current density, the total dissipated power, and the braking torque are given. Examination of the topology of current lines reveals that depending upon the relative dimensions of the side and length of the toroid two different regimes exist. The conditions of existence of the two regimes are analytically established. In view of nuclear magnetic resonance (NMR) applications, we derive the angular variation of the magnetic field created by eddy currents and lay down the formalism necessary for calculating the effect of this field on the NMR spectra of the conductor itself or of a sample co-rotating with the conductor, a situation encountered when dealing with rotating detectors. Examples of calculations for cases of practical interest are presented. The theory is confronted with available data, and we give guidelines for the design of optimized rotating micro-coils.

  12. Heat generation by eddy currents in a shell of superconducting bus-bars for SIS100 particle accelerator at FAIR

    Directory of Open Access Journals (Sweden)

    Tomków Łukasz

    2017-12-01

    Full Text Available Superconducting magnets in the SIS100 particle accelerator require the supply of liquid helium and electric current. Both are transported with by-pass lines designed at Wrocław University of Technology. Bus-bars used to transfer an electric current between the sections of the accelerator will be encased in a steel shell. Eddy currents are expected to appear in the shell during fast-ramp operation of magnets. Heat generation, which should be limited in any cryogenic system, will appear in the shell. In this work the amount of heat generated is assessed depending on the geometry of an assembly of the bus-bars and the shell. Numerical and analytical calculations are described. It was found that heat generation in the shell is relatively small when compared to other sources present in the accelerator and its value strongly depends on the geometry of the shell. The distribution of eddy currents and generated heat for different geometrical options are presented. Based on the results of the calculations the optimal design is proposed.

  13. Calculation of equivalent magnetic permeability of ferromagnetic materials for modeling of three-dimensional eddy current fields

    Directory of Open Access Journals (Sweden)

    Karpushkin Sergey

    2017-01-01

    Full Text Available The paper presents a method of calculating a constant value of magnetic permeability of ferromagnetic materials, equivalent to the basic magnetization curve by the criterion of real power. The proposed method makes it possible to use linear differential equations of the electromagnetic field in the analysis of three-dimensional fields of eddy currents in ferromagnetic materials, thus significantly reducing the calculation time. We propose a method of calculating the power of inductors using two-dimensional axisymmetric models. The scope of the proposed methods is limited to the case of placement of the inductor inside the ferromagnetic body.

  14. Acceptance testing of the eddy current probes for measurement of aluminum hydroxide coating thickness on K West Basin fuel elements

    Energy Technology Data Exchange (ETDEWEB)

    Pitner, A.L.

    1998-08-21

    During a recent visual inspection campaign of fuel elements stored in the K West Basin, it was noted that fuel elements contained in sealed aluminum canisters had a heavy translucent type coating on their surfaces (Pitner 1997a). Subsequent sampling of this coating in a hot cell (Pitner 1997b) and analysis of the material identified it as aluminum hydroxide. Because of the relatively high water content of this material, safety related concerns are raised with respect to long term storage of this fuel in Multi-Canister Overpacks (MCOs). A campaign in the basin is planned to demonstrate whether this coating can be removed by mechanical brushing (Bridges 1998). Part of this campaign involves before-and-after measurements of the coating thickness to determine the effectiveness of coating removal by the brushing machine. Measurements of the as-deposited coating thickness on multiple fuel elements are also expected to provide total coating inventory information needed for MCO safety evaluations. The measurement technique must be capable of measuring coating thicknesses on the order of several mils, with a measurement accuracy of 0.5 mil. Several different methods for quantitatively measuring these thin coatings were considered in selecting the most promising approach. Ultrasonic measurement was investigated, but it was determined that due to the thin coating depth and the high water content of the material, the signal would likely pass directly through to the cladding without ever sensing the coating surface. X-ray fluorescence was also identified as a candidate technique, but would not work because the high gamma background from the irradiated fuel would swamp out the low energy aluminum signal. Laser interferometry could possibly be applied, but considerable development would be required and it was considered to be high risk on a short term basis. The consensus reached was that standard eddy current techniques for coating thickness measurement had the best chance for

  15. Development of a resonant repeater tag for the enhancement of sensitivity and specificity in a wireless eddy current sensing scheme

    Science.gov (United States)

    Woo, Byungki; Andringa, Matthew; Wood, Sharon; Neikirk, Dean P.

    2006-03-01

    Eddy current sensing has been successfully used in various applications from testing heat exchange tubes for nuclear power plants to assessing dielectric thickness on printed circuit boards. However, in civil infrastructures cosmetic or cementitious surface material often keeps the probe or reader coil from accessing conductive medium inside the structure, resulting in reduced coupling as the distance increases between the DUT (device under test) and probe. Thus, the direct application of existing eddy current sensing technique is not very useful to detect flaws in civil infrastructures. To address this weak coupling problem, a simple scheme is proposed in which a resonant passive repeater tag is placed between the reader coil and the conducting test target. In this paper, the feasibility of detecting defects like cracks or fractures in conductive medium using a passive resonant tag and remote inductive pick-up as a method of interrogation is shown. Experimental data taken from simple setups to demonstrate the advantage of the proposed scheme are presented.

  16. Computer-aided design of multifrequency eddy-current tests for layered conductors with multiple property variations

    Energy Technology Data Exchange (ETDEWEB)

    Deeds, W E; Dodd, C V; Scott, G W

    1979-10-01

    Our program is part of a larger project designed to develop multifrequency eddy-current inspection techniques for multilayered conductors with parallel planar boundaries. To reduce the need to specially program each new problem, a family of programs that handle a large class of related problems with only minor editorial and interactive changes were developed. Programs for two types of cylindrical coil probes were developed: the reflection probe, which contains the driver and pickup coils and is used from one side of the specimen, and the through-transmission probe set, which places the driver and pickup coils on opposite sides of the conductor stack. The programs perform the following basic functions: (1) simulation of an ideal instrument's response to specific conductor and defect configurations, (2) control of an eddy-current instrument interfaced to a minicomputer to acquire and record actual instrument responses to test specimens, (3) construction of complex function expansions to relate instrument response to conductor and defect properties by using measured or computed responses and properties, and (4) simulation of a microcomputer on board the instrument by the interfaced minicomputer to test the analytical programming for the microcomputer. The report contains the basic equations for the computations, the main and subroutine programs, instructions for editorial changes and program execution, analyses of the main programs, file requirements, and other miscellaneous aids for the user.

  17. Direct Drive and Eddy Current Septa Magnet Designs for CERN’s PSB Extraction at 2 GeV

    CERN Multimedia

    Szoke, Zsolt; Balhan, Bruno; Baud, Cedric; Borburgh, Jan; Hourican, Michael; Masson, Thierry; Prost, Antoine

    2015-01-01

    In the framework of the LIU project, new septa magnets have been designed between CERN’s PS Booster (PSB) extraction and PS injection. The upgraded devices are to deal with the increased beam energy from 1.4 GeV to 2 GeV at extraction of the PSB. The direct drive recombination septa in the PSB transfer line to the PS, the eddy current PS injection septum together with a bumper at injection have been investigated using finite element software. For the recombination magnets an increase in magnet length is sufficient to obtain the required deflection; however, for the PS injection elements a more novel solution is necessary to also achieve increased robustness to extend the expected lifetime of the pulsed device. The injection septum will share the same vacuum vessel with an injection bumper and both magnets will be located adjacent to each other. The new PS injection magnet will be the first septum operated at CERN based on eddy current technology. The magnetic modelling of the devices, the comparison of the ...

  18. submitter Direct Drive and Eddy Current Septa Magnet Designs for CERN's PSB Extraction at 2 GeV

    CERN Document Server

    Szoke, Z; Balhan, B; Baud, C; Borburgh, J; Hourican, M; Masson, T; Prost, A

    2016-01-01

    In the framework of the LIU project, new septa magnets have been designed between CERN's PS booster (PSB) extraction and PS injection. The upgraded devices are to deal with the increased beam energy from 1.4 to 2 GeV at extraction of the PSB. The direct drive recombination septa in the PSB transfer line to the PS and the eddy current PS injection septum together with a bumper at injection have been investigated using finite-element software. For the recombination magnets, an increase in magnet length is sufficient to obtain the required deflection; however, for the PS injection elements, a more novel solution is necessary to also achieve increased robustness to extend the expected lifetime of the pulsed device. The injection septum will share the same vacuum vessel with an injection bumper, and both magnets will be located adjacent to each other. The new PS injection magnet will be the first septum operated at CERN based on eddy current technology. The magnetic modeling of the devices, the comparison of the p...

  19. A fiber-optic current sensor for aerospace applications

    Energy Technology Data Exchange (ETDEWEB)

    Patterson, R.L. [Lewis Research Center, Cleveland, OH (United States); Rose, A.H.; Tang, D.; Day, G.W. [National Institute of Standards and Technology, Boulder, CO (United States)

    1994-09-01

    A robust, accurate, broad-band, alternating current sensor using fiber optics is being developed for space applications at power frequencies as high as 20 kHz. It can also be used in low and high voltage 60 Hz terrestrial power systems and in 400 Hz aircraft systems. It is intrinsically EMI immune and has the added benefit of excellent isolation. The sensor uses the Faraday effect in optical fiber and standard polarimetric measurements to sense electrical current. The primary component of the sensor is a specially treated coil of single-mode optical fiber, through which the current carrying conductor passes. Improved precision is accomplished by temperature compensation by means of signals from a novel fiber-optic temperature sensor embedded in the sensing head. This paper reports on the technology contained in the sensor and also relates the results of precision tests conducted at various temperatures within the wide operating range. It also shows the results of early EMI tests.

  20. Experimental and numerical examination of eddy (Foucault) currents in rotating micro-coils: Generation of heat and its impact on sample temperature.

    Science.gov (United States)

    Aguiar, Pedro M; Jacquinot, Jacques-François; Sakellariou, Dimitris

    2009-09-01

    The application of nuclear magnetic resonance (NMR) to systems of limited quantity has stimulated the use of micro-coils (diameter Foucault (eddy) currents, which generate heat. We report the first data acquired with a 4mm MACS system and spinning up to 10kHz. The need to spin faster necessitates improved methods to control heating. We propose an approximate solution to calculate the power losses (heat) from the eddy currents for a solenoidal coil, in order to provide insight into the functional dependencies of Foucault currents. Experimental tests of the dependencies reveal conditions which result in reduced sample heating and negligible temperature distributions over the sample volume.

  1. Magnetoresistive Current Sensors for High Accuracy, High Bandwidth Current Measurement in Spacecraft Power Electronics

    Science.gov (United States)

    Slatter, Rolf; Goffin, Benoit

    2014-08-01

    The usage of magnetoresistive (MR) current sensors is increasing steadily in the field of power electronics. Current sensors must not only be accurate and dynamic, but must also be compact and robust. The MR effect is the basis for current sensors with a unique combination of precision and bandwidth in a compact package. A space-qualifiable magnetoresistive current sensor with high accuracy and high bandwidth is being jointly developed by the sensor manufacturer Sensitec and the spacecraft power electronics supplier Thales Alenia Space (T AS) Belgium. Test results for breadboards incorporating commercial-off-the-shelf (COTS) sensors are presented as well as an application example in the electronic control and power unit for the thrust vector actuators of the Ariane5-ME launcher.

  2. Optimization of magnetoresistive sensor current for on-chip magnetic bead detection using the sensor self-field

    DEFF Research Database (Denmark)

    Henriksen, Anders Dahl; Rizzi, Giovanni; Østerberg, Frederik Westergaard

    2015-01-01

    current while limiting the sensor self-heating. We systematically characterize and model the Joule heating of magnetoresistive sensors with different sensor geometries and stack compositions. The sensor heating is determined using the increase of the sensor resistance as function of the bias current...

  3. Delta-Sigma Digital Current Sensor Based On GMR

    Energy Technology Data Exchange (ETDEWEB)

    Wang Zhili; Qian Zhenghong; Huang Xiaowei, E-mail: zqian@hdu.edu.cn [Center for Integrated Spintronic Devices, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2011-01-01

    This paper presents an integrated delta-sigma digital current sensor. With high sensitivity and good linearity, GMR sensor is a good choice for current measurement application. In this design, a GMR sensor which is configured as a Wheatstone bridge of four spin-valve sensing elements is integrated with CMOS signal processing circuit together, and the output signal is converted to digital domain by an on-chip 10-bit delta-sigma ADC. The whole circuit is designed and simulated using CSMC standard 0.5 {mu}m process.

  4. An Improved Model Predictive Current Controller of Switched Reluctance Machines Using Time-Multiplexed Current Sensor.

    Science.gov (United States)

    Li, Bingchu; Ling, Xiao; Huang, Yixiang; Gong, Liang; Liu, Chengliang

    2017-05-17

    This paper presents a fixed-switching-frequency model predictive current controller using multiplexed current sensor for switched reluctance machine (SRM) drives. The converter was modified to distinguish currents from simultaneously excited phases during the sampling period. The only current sensor installed in the converter was time division multiplexing for phase current sampling. During the commutation stage, the control steps of adjacent phases were shifted so that sampling time was staggered. The maximum and minimum duty ratio of pulse width modulation (PWM) was limited to keep enough sampling time for analog-to-digital (A/D) conversion. Current sensor multiplexing was realized without complex adjustment of either driver circuit nor control algorithms, while it helps to reduce the cost and errors introduced in current sampling due to inconsistency between sensors. The proposed controller is validated by both simulation and experimental results with a 1.5 kW three-phase 12/8 SRM. Satisfied current sampling is received with little difference compared with independent phase current sensors for each phase. The proposed controller tracks the reference current profile as accurately as the model predictive current controller with independent phase current sensors, while having minor tracking errors compared with a hysteresis current controller.

  5. Eddy current loss analysis of open-slot fault-tolerant permanent-magnet machines based on conformal mapping method

    Science.gov (United States)

    Ji, Jinghua; Luo, Jianhua; Lei, Qian; Bian, Fangfang

    2017-05-01

    This paper proposed an analytical method, based on conformal mapping (CM) method, for the accurate evaluation of magnetic field and eddy current (EC) loss in fault-tolerant permanent-magnet (FTPM) machines. The aim of modulation function, applied in CM method, is to change the open-slot structure into fully closed-slot structure, whose air-gap flux density is easy to calculate analytically. Therefore, with the help of Matlab Schwarz-Christoffel (SC) Toolbox, both the magnetic flux density and EC density of FTPM machine are obtained accurately. Finally, time-stepped transient finite-element method (FEM) is used to verify the theoretical analysis, showing that the proposed method is able to predict the magnetic flux density and EC loss precisely.

  6. Lightning Current Measurement with Fiber-Optic Sensor

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

    2014-01-01

    A fiber-optic current sensor is successfully developed with many potential applications for electric current measurement. Originally developed for in-flight lightning measurement, the sensor utilizes Faraday Effect in an optical fiber. The Faraday Effect causes linear light polarization in a fiber to rotate when the fiber is exposed to a magnetic field. The polarization change is detected using a reflective polarimetric scheme. Forming fiber loops and applying Ampere's law, measuring the total light rotation results in the determination of the total current enclosed. The sensor is conformable to complex structure geometry. It is also non-conductive and immune to electromagnetic interference, saturation or hysteresis. Installation is non-intrusive, and the sensor can be safely routed through flammable areas. Two similar sensor systems are described in this paper. The first system operates at 1310nm laser wavelength and is capable of measuring approximately 300 A - 300 kA, a 60 dB range. Laboratory validation results of aircraft lighting direct and in-direct effect current amplitudes are reported for this sensor. The second system operates at 1550nm wavelength and can measure about 400 A - 400 kA. Triggered-lightning measurement data are presented for this system. Good results are achieved in all cases.

  7. Fiber-Optic Sensor for Aircraft Lightning Current Measurement

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George G.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

    2012-01-01

    An electric current sensor based on Faraday rotation effect in optical fiber was developed for measuring aircraft lightning current. Compared to traditional sensors, the design has many advantages including the ability to measure total current and to conform to structure geometries. The sensor is also small, light weight, non-conducting, safe from interference, and free of hysteresis and saturation. Potential applications include characterization of lightning current waveforms, parameters and paths, and providing environmental data for aircraft certifications. In an optical fiber as the sensing medium, light polarization rotates when exposed to a magnetic field in the direction of light propagation. By forming closed fiber loops around a conductor and applying Ampere s law, measuring the total light rotation yields the enclosed current. A reflective polarimetric scheme is used, where polarization change is measured after the polarized light travels round-trip through the sensing fiber. The sensor system was evaluated measuring rocket-triggered lightning over the 2011 summer. Early results compared very well against a reference current shunt resistor, demonstrating the sensor s accuracy and feasibility in a lightning environment. While later comparisons show gradually increasing amplitude deviations for an undetermined cause, the overall waveforms still compared very well.

  8. Intercomparison of six fast-response sensors for the eddy-covariance flux measurement of nitrous oxide over agricultural grassland

    Science.gov (United States)

    Nemitz, Eiko; Famulari, Daniela; Ibrom, Andreas; Vermeulen, Alex; Hensen, Arjan; van den Bulk, Pim; Loubet, Benjamin; Laville, Patricia; Mammarella, Ivan; Haapanala, Sami; Lohila, Annalea; Laurila, Tuomas; Eva, Rabot; Laborde, Marie; Cowan, Nicholas; Anderson, Margaret; Helfter, Carole

    2015-04-01

    Nitrous oxide (N2O) is the third most important greenhouse gas and its terrestrial budget remains poorly constraint, with bottom up and top down estimates of country emissions often disagreeing by more than a factor of two. Whilst the measurements of the biosphere / atmosphere exchange of CO2 with micrometeorological methods is commonplace, emissions of CH4 and N2O are more commonly measured with enclosure techniques due to limitations in fast-response sensors with good signal-to-noise characteristics. Recent years have seen the development of a range of instruments based on optical spectroscopy. This started in the early 1990s with instruments based on lead salt lasers, which had temperamental long-term characteristics. More recent developments in quantum cascade lasers has lead to increasingly stable instruments, initially based on pulsed, later on continuous wave lasers. Within the context of the European FP7 Infrastructure Project InGOS ('Integrated non-CO2 Greenhouse gas Observing System'), we conducted an intercomparison of six fast response sensors for N2O: three more or less identical instruments based on off-axis Integrated Cavity Optical Spectrocopy (ICOS) (Los Gatos Research Inc.) and three instruments based on quantum cascade laser absorption spectrometry (Aerodyne Research Inc.): one older generation pulsed instrument (p-QCL) and two of the latest generation of compact continuous wave instruments (cw-QCL), operating at two different wavelengths. One of the ICOS instruments was operated with an inlet drier. In addition, the campaign was joined by a relaxed eddy-accumulation system linked to a FTIR spectrometer (Ecotech), a gradient system based on a home-built slower QCL (INRA Orleans) and a fast chamber system. Here we present the results of the study and a detailed examination of the various corrections and errors of the different instruments. Overall, with the exception of the older generation QCL, the average fluxes based on the different fast

  9. Development of optoelectronic-based pulsed current sensor to ...

    Indian Academy of Sciences (India)

    Anil S Nayak

    2017-08-03

    Aug 3, 2017 ... the poor laser discharge condition. ANIL S NAYAK*, RAJASREE VIJAYAN, ... Abstract. A current transformer (CT)-based sensor has been developed to detect poor discharge conditions in copper vapour laser. ..... the system is currently underway to ensure no human intervention during such abnormal ...

  10. Intelligent Current Sensors as Part of Smart Grid Network

    Directory of Open Access Journals (Sweden)

    Andrzej Nowakowski

    2015-06-01

    Full Text Available The continuous development of the ITC systems, especially industrial Ethernet network using the IEC 61850 protocol allows to building a distributed sensor networks for control and monitor temporary states of the power infrastructure. In the paper the construction of the intelligent current sensors, Measurement Units (MU for the Smart Grid network has been presented. In the paper the circuit diagram of sensor and synchronization method of the analog to digital converter based on the UTC timestamps has been described. The presented method allows to synchronize intelligent current sensors with an accuracy better than 1 μs. The presented innovative synchronization method is characterized by a high level of resistance to disappearance and attack of the reference time signal. The measuring device MU design is based on the embedded Linux-platform and as a sensing element used air core current transducers based on Rogowski coil. The connection between the current transducers and the central unit is made using a fiber optic link. Built-in IEC-61850 server provides a real-time measurement value of the True RMS, harmonics spectrum and samples value. The intelligent current transducers in addition to being used in the MUs create also new possibilities in the substation construction like the possibility to place the Autonomous Sensors in large distance from Intelligent Electronic Devices that are located in the substation.

  11. Advances based on digital technology named TEDDY+ for inspection of eddy current; Avances a partir de las prestaciones digitales del sistema de inspeccion de corrientes inducidas TEDDY+

    Energy Technology Data Exchange (ETDEWEB)

    Barcenilla, V.; Hernandez, J.; Ribes, B.

    2007-07-01

    As a result of the recent developing line of eddy current data acquisition system a new product based on digital technology named TEDDY+, comes to the market. With only 4 kg of weight constitutes a great advance with regards to other equipment's available in the market. These advances, have enabled, among others, to increase considerably the signal to noise (S/N) ratio, avoid typical saturation problems in the eddy current signal, increase the inspection speed, eliminate the reference probe, detect the air/tube signal in real time, and the possibility to integrate the tester inside a push puller thanks to its reduced size and to have integrated as part of the ET equipment the mechanical systems control board. Two product lines have been developed, one oriented to any market and application (nuclear market, industrial and aeronautical, chemical and petrochemical, etc) and other specially dedicated to the massive inspection of tubes, named TEDDY+SP (Suitcase Pusher). Both lines are prepared to use eddy current arrays which clearly constitute the future of the eddy current inspection systems. The new TEDDY+ line of products presented in this paper constitutes one of the most powerful and reliable existing in the market. These improvements and novelties place the new ET inspection system from Tecnatom as one of the most powerful and reliable in the market. (Author)

  12. A Neuron Model Based Ultralow Current Sensor System for Bioapplications

    Directory of Open Access Journals (Sweden)

    A. K. M. Arifuzzman

    2016-01-01

    Full Text Available An ultralow current sensor system based on the Izhikevich neuron model is presented in this paper. The Izhikevich neuron model has been used for its superior computational efficiency and greater biological plausibility over other well-known neuron spiking models. Of the many biological neuron spiking features, regular spiking, chattering, and neostriatal spiny projection spiking have been reproduced by adjusting the parameters associated with the model at hand. This paper also presents a modified interpretation of the regular spiking feature in which the firing pattern is similar to that of the regular spiking but with improved dynamic range offering. The sensor current ranges between 2 pA and 8 nA and exhibits linearity in the range of 0.9665 to 0.9989 for different spiking features. The efficacy of the sensor system in detecting low amount of current along with its high linearity attribute makes it very suitable for biomedical applications.

  13. Utilization of Faraday Mirror in Fiber Optic Current Sensors

    Directory of Open Access Journals (Sweden)

    P. Fiala

    2008-12-01

    Full Text Available Fiber optic sensors dispose of some advantages in the field of electrical current and magnetic field measurement, like large bandwidth, linearity, light transmission possibilities. Unfortunately, they suffer from some parasitic phenomena. The crucial issue is the presence of induced and latent linear birefringence, which is imposed by the fiber manufacture imperfections as well as mechanical stress by fiber bending. In order to the linear birefringence compensation a promising method was chosen for pulsed current sensor design. The method employs orthogonal polarization conjugation by the back direction propagation of the light wave in the fiber. The Jones calculus analysis presents its propriety. An experimental fiber optic current sensor has been designed and realized. The advantage of the proposed method was proved considering to the sensitivity improvement.

  14. Examination of pulsed eddy current for inspection of second layer aircraft wing lap-joint structures using outlier detection methods

    Energy Technology Data Exchange (ETDEWEB)

    Butt, D.M., E-mail: Dennis.Butt@forces.gc.ca [Royal Military College of Canada, Dept. of Chemistry and Chemical Engineering, Kingston, Ontario (Canada); Underhill, P.R.; Krause, T.W., E-mail: Thomas.Krause@rmc.ca [Royal Military College of Canada, Dept. of Physics, Kingston, Ontario (Canada)

    2016-09-15

    Ageing aircraft are susceptible to fatigue cracks at bolt hole locations in multi-layer aluminum wing lap-joints due to cyclic loading conditions experienced during typical aircraft operation, Current inspection techniques require removal of fasteners to permit inspection of the second layer from within the bolt hole. Inspection from the top layer without fastener removal is desirable in order to minimize aircraft downtime while reducing the risk of collateral damage. The ability to detect second layer cracks without fastener removal has been demonstrated using a pulsed eddy current (PEC) technique. The technique utilizes a breakdown of the measured signal response into its principal components, each of which is multiplied by a representative factor known as a score. The reduced data set of scores, which represent the measured signal, are examined for outliers using cluster analysis methods in order to detect the presence of defects. However, the cluster analysis methodology is limited by the fact that a number of representative signals, obtained from fasteners where defects are not present, are required in order to perform classification of the data. Alternatively, blind outlier detection can be achieved without having to obtain representative defect-free signals, by using a modified smallest half-volume (MSHV) approach. Results obtained using this approach suggest that self-calibrating blind detection of cyclic fatigue cracks in second layer wing structures in the presence of ferrous fasteners is possible without prior knowledge of the sample under test and without the use of costly calibration standards. (author)

  15. Anomalous enhancement of eddy-current anomaly factor in very soft ferromagnetic wires[75.30.Cr; 75.50.Kj; 75.60.Ej; Circular permeability; Eddy-current anomaly factor; Magnetic inclusions; Soft ferromagnetic wires

    Energy Technology Data Exchange (ETDEWEB)

    Li, Y.-F. E-mail: yinfengli2001@yahoo.com; Chen, D.-X.; Vazquez, M

    2004-01-01

    The circular permeability, {mu}={mu}'-j{mu}'', of two very soft ferromagnetic wires (Co{sub 68.2}Fe{sub 4.3}Si{sub 12.5}B{sub 15} amorphous wire S1 and Fe{sub 73.5}Cu{sub 1}Nb{sub 3}Si{sub 13.5}B{sub 9} nanocrystalline wire S2) has been determined from the measurements of the impedance, Z=R+j{omega}L, as a function of frequency (f=0.1-100 kHz) and DC bias field (H=0-89 kA/m). The axial field-dependent DC circular permeability, {mu}{sub DC}(H), of two samples exhibit the anomalous enhancement phenomenon as we observed in the similar samples before. The change of the low-f eddy-current anomaly factor, {eta}, with H has been studied. With increasing H from 0 to 3600 A/m, {eta} increase from 1.4 to 8.5 and from 2.8 to 4.2 for samples S1 and S2, respectively, which is contrary to the theoretical expectation that {eta}(H) approaches the value of {eta}=1 with the sample being saturated. This anomalous behavior of {eta}(H) is analyzed in terms of the micro-domain structure resulted from magneto-static interaction between the magnetically hard inclusions and the soft matrix.

  16. Development of optoelectronic-based pulsed current sensor to ...

    Indian Academy of Sciences (India)

    ... Refresher Courses · Symposia · Live Streaming. Home; Journals; Sadhana; Volume 42; Issue 10. Development of optoelectronic-based pulsed current sensor to detect the poor laser discharge condition. ANIL S NAYAK RAJASREE VIJAYAN DEEPAK NAPHADE V S RAWAT K G MANOHAR. Volume 42 Issue 10 October ...

  17. Increased Speed: 3D Silicon Sensors; Fast Current Amplifiers

    CERN Document Server

    Parker, S; Hasi, J; Da Via, C; Despeisse, M; Anelli, G; Kenney, C; Jarron, P

    2011-01-01

    The authors describe techniques to make fast, sub-nanosecond time resolution solid-state detector systems using sensors with 3D electrodes, current amplifiers, constant-fraction comparators or fast wave-form recorders, and some of the next steps to reach still faster results.

  18. Efficient solution of 3D electromagnetic eddy-current problems within the finite volume framework of OpenFOAM

    Science.gov (United States)

    Beckstein, Pascal; Galindo, Vladimir; Vukčević, Vuko

    2017-09-01

    Eddy-current problems occur in a wide range of industrial and metallurgical applications where conducting material is processed inductively. Motivated by realising coupled multi-physics simulations, we present a new method for the solution of such problems in the finite volume framework of foam-extend, an extended version of the very popular OpenFOAM software. The numerical procedure involves a semi-coupled multi-mesh approach to solve Maxwell's equations for non-magnetic materials by means of the Coulomb gauged magnetic vector potential A and the electric scalar potential ϕ. The concept is further extended on the basis of the impressed and reduced magnetic vector potential and its usage in accordance with Biot-Savart's law to achieve a very efficient overall modelling even for complex three-dimensional geometries. Moreover, we present a special discretisation scheme to account for possible discontinuities in the electrical conductivity. To complement our numerical method, an extensive validation is completing the paper, which provides insight into the behaviour and the potential of our approach.

  19. Techniques for processing remote field eddy current signals from bend regions of steam generator tubes of prototype fast breeder reactor

    Energy Technology Data Exchange (ETDEWEB)

    Thirunavukkarasu, S. [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India); Rao, B.P.C., E-mail: bpcrao@igcar.gov.in [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India); Jayakumar, T.; Raj, Baldev [Non Destructive Evaluation Division, Indira Gandhi Centre for Atomic Research, Kalpakkam, TN 603 102 (India)

    2011-04-15

    Steam generator (SG) is one of the most critical components of sodium cooled fast breeder reactor. Remote field eddy current (RFEC) technique has been chosen for in-service inspection (ISI) of these ferromagnetic SG tubes made of modified 9Cr-1Mo steel (Grade 91). Expansion bends are provided in the SGs to accommodate differential thermal expansion. During ISI using RFEC technique, in expansion bend regions, exciter-receiver coil misalignment, bending stresses, probe wobble and magnetic permeability variations produce disturbing noise hindering detection of defects. Fourier filtering, cross-correlation and wavelet transform techniques have been studied for noise reduction as well as enhancement of RFEC signals of defects in bend regions, having machined grooves and localized defects. Performance of these three techniques has been compared using signal-to-noise ratio (SNR). Fourier filtering technique has shown better performance for noise reduction while cross-correlation technique has resulted in significant enhancement of signals. Wavelet transform technique has shown the combined capability of noise reduction and signal enhancement and resulted in unambiguous detection of 10% of wall loss grooves and localized defects in the bend regions with SNR better than 7 dB.

  20. A Fiber-Optic Aircraft Lightning Current Measurement Sensor

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

    2013-01-01

    A fiber-optic current sensor based on the Faraday Effect is developed for aircraft installations. It can measure total lightning current amplitudes and waveforms, including continuing current. Additional benefits include being small, lightweight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate in presence of magnetic field in the direction of light propagation. Measuring the total induced light polarization change yields the total current enclosed. The system operates at 1310nm laser wavelength and can measure approximately 300 A - 300 kA, a 60 dB range. A reflective polarimetric scheme is used, where the light polarization change is measured after a round-trip propagation through the fiber. A two-detector setup measures the two orthogonal polarizations for noise subtraction and improved dynamic range. The current response curve is non-linear and requires a simple spline-fit correction. Effects of high current were achieved in laboratory using combinations of multiple fiber and wire loops. Good result comparisons against reference sensors were achieved up to 300 kA. Accurate measurements on a simulated aircraft fuselage and an internal structure illustrate capabilities that maybe difficult with traditional sensors. Also tested at a commercial lightning test facility from 20 kA to 200 kA, accuracy within 3-10% was achieved even with non-optimum setups.

  1. Limitations and Constraints of Eddy-Current Loss Models for Interior Permanent-Magnet Motors with Fractional-Slot Concentrated Windings

    Directory of Open Access Journals (Sweden)

    Hui Zhang

    2017-03-01

    Full Text Available This paper analyzes and compares models for predicting average magnet losses in interior permanent-magnet motors with fractional-slot concentrated windings due to harmonics in the armature reaction (assuming sinusoidal phase currents. Particularly, loss models adopting different formulations and solutions to the Helmholtz equation to solve for the eddy currents are compared to a simpler model relying on an assumed eddy-current distribution. Boundaries in terms of magnet dimensions and angular frequency are identified (numerically and using an identified approximate analytical expression to aid the machine designer whether the more simple loss model is applicable or not. The assumption of a uniform flux-density variation (used in the loss models is also investigated for the case of V-shaped and straight interior permanent magnets. Finally, predicted volumetric loss densities are exemplified for combinations of slot and pole numbers common in automotive applications.

  2. Development of High Resolution Eddy Current Imaging Using an Electro-Mechanical Sensor (Postprint)

    Science.gov (United States)

    2011-08-01

    magnetic tip cantilever of a MFM equipped with a piezoelectric element was brought close to an electrical conductor and was vibrated. A vibrating...displacements with a laser vibrometer . Displacement was estimated to be at 8.2 nm in magnitude. These values were plugged into equation (1) assuming

  3. Advanced induction motor drive control with single current sensor

    Directory of Open Access Journals (Sweden)

    Adžić Evgenije M.

    2016-01-01

    Full Text Available This paper proposes induction motor drive control method which uses minimal number of sensors, providing only DC-link current as a feedback signal. Improved DC-link current sampling scheme and modified asymmetrical switching pattern cancels characteristic waveform errors which exist in all three reconstructed motor line-currents. Motor linecurrent harmonic content is reduced to an acceptable level, eliminating torque and speed oscillations which were inherent for conventional single sensor drives. Consequently, use of single current sensor and line-current reconstruction technique is no longer acceptable only for low and medium performance drives, but also for drives where priority is obtaining a highly accurate, stable and fast response. Proposed control algorithm is validated using induction motor drive hardware prototype based on TMS320F2812 digital signal processor. [Projekat Ministarstva nauke Republike Srbije, br. III 042004 and by the Provincial Secretariat for Science and Technological Development of AP Vojvodina under contract No. 114-451-3508/2013-04

  4. A feasibility study of altered spatial distribution of losses induced by eddy currents in body composition analysis

    Directory of Open Access Journals (Sweden)

    Sepponen Raimo E

    2010-11-01

    Full Text Available Abstract Background Tomographic imaging has revealed that the body mass index does not give a reliable state of overall fitness. However, high measurement costs make the tomographic imaging unsuitable for large scale studies or repeated individual use. This paper reports an experimental investigation of a new electromagnetic method and its feasibility for assessing body composition. The method is called body electrical loss analysis (BELA. Methods The BELA method uses a high-Q parallel resonant circuit to produce a time-varying magnetic field. The Q of the resonator changes when the sample is placed in its coil. This is caused by induced eddy currents in the sample. The new idea in the BELA method is the altered spatial distribution of the electrical losses generated by these currents. The distribution of losses is varied using different excitation frequencies. The feasibility of the method was tested using simplified phantoms. Two of these phantoms were rough estimations of human torso. One had fat in the middle of its volume and saline solution in the outer shell volume. The other had reversed conductivity distributions. The phantoms were placed in the resonator and the change in the losses was measured. Five different excitation frequencies from 100 kHz to 200 kHz were used. Results The rate of loss as a function of frequency was observed to be approximately three times larger for a phantom with fat in the middle of its volume than for one with fat in its outer shell volume. Conclusions At higher frequencies the major signal contribution can be shifted toward outer shell volume. This enables probing the conductivity distribution of the subject by weighting outer structural components. The authors expect that the loss changing rate over frequency can be a potential index for body composition analysis.

  5. Temperature compensated and self-calibrated current sensor using reference magnetic field

    Science.gov (United States)

    Yakymyshyn, Christopher Paul; Brubaker, Michael Allen; Yakymyshyn, Pamela Jane

    2007-10-09

    A method is described to provide temperature compensation and self-calibration of a current sensor based on a plurality of magnetic field sensors positioned around a current carrying conductor. A reference magnetic field generated within the current sensor housing is detected by the magnetic field sensors and is used to correct variations in the output signal due to temperature variations and aging.

  6. Fiber-Optic Current Sensor Validation with Triggered Lightning Measurements

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel G.; Snyder, Gary P.

    2013-01-01

    A fiber optic current sensor based on the Faraday Effect is developed that is highly suitable for aircraft installation and can measure total current enclosed in a fiber loop down to DC. Other attributes include being small, light-weight, non-conducting, safe from electromagnetic interference, and free of hysteresis and saturation. The Faraday Effect causes light polarization to rotate when exposed to a magnetic field in the direction of light propagation. Measuring the induced light polarization rotation in fiber loops yields the total current enclosed. Two sensor systems were constructed and installed at Camp Blanding, Florida, measuring rocket-triggered lightning. The systems were similar in design but with different laser wavelengths, sensitivities and ranges. Results are compared to a shunt resistor as reference. The 850nm wavelength system tested in summer 2011 showed good result comparison early. However, later results showed gradual amplitude increase with time, attributed to corroded connections affecting the 50-ohm output termination. The 1550nm system also yielded good results in the summer 2012. The successful measurements demonstrate the fiber optic sensor's accuracies in capturing real lightning currents, and represent an important step toward future aircraft installation.

  7. Reducing the Impact of Electroconductivity and the Gap between the Pipe and the Transducer at Measuring Thickness of Electroconductive Pipe Walls using the Eddy-Current Method

    Directory of Open Access Journals (Sweden)

    Yakimov Evgeny

    2016-01-01

    Full Text Available The paper describes a dual-frequency method for reducing the impact of changes in the gap size between the eddy-current transducer and the pipe, as well as the pipe electrical conductivity on the eddy-current thickness gauge readings. A block-diagram of the dual-frequency eddycurrent thickness gauge is proposed for light-alloy drill pipes. The amplitude and signal phase dependencies on the wall thickness in the range from 6 to 17 mm and the gap in the range from 0 to 13.5 mm were studied, the results are presented. The digital signal processing algorithms based on the piecewise-linear approximation of low-frequency and high-frequency signal phase dependencies on the wall thickness are proposed. It is shown that the proposed correction algorithms can reduce the error caused by variations of electrical conductivity and the gap between the transducer and the pipe.

  8. A Fiber-Optic Current Sensor for Lightning Measurement Applications

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.

    2015-01-01

    An optical-fiber sensor based on Faraday Effect is developed for measuring total lightning electric current. It has many unique capabilities not possible with traditional current sensors. Designed for aircraft installation, the sensor is lightweight, non-conducting, structure-conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can also be used on windmills, lightning towers, and can help validate lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. The broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with about 60 dB dynamic range. Three sensor systems were built with different sensitivities from different laser wavelengths. Operating at 850nm, the first system uses twisted single-mode fiber and has a 150 A - 150 KA range. The second system operates at 1550nm, uses spun polarization maintaining fiber, and can measure 400 A - 400 KA. Both systems were validated with rocket-triggered lightning measurements and achieved excellent results when compared to a resistive shunt. The third system operates at 1310nm, uses spun polarization maintaining fiber, and can measure approximately 300 A - 300 KA. High current measurements up to 200 KA were demonstrated at a commercial lightning test facility. The system was recently installed on an aircraft and flown near icing weather conditions.

  9. Eddy current examination of the nuclear fuel elements with aluminum 1100-F cladding of IPR-R1 research reactor: An initial study

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Roger F. da; Silva Júnior, Silvério F. da; Frade, Rangel T. [Centro de Desenvolvimento da Tecnologia Nucelar (CDTN/CNEN-MG), Belo Horizonte, MG (Brazil); Rodrigues, Juliano S., E-mail: rfs@cdtn.br, E-mail: silvasf@cdtn.br, E-mail: rtf@cdtn.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2017-07-01

    Tubes of aluminum 1100-F as well as tubes of AISI 304 stainless steel are used as cladding of the fuel elements of TRIGA IPR-R1 nuclear research reactor. Usually, these tubes are inspected by means of visual test and sipping test. The visual test allows the detection of changes occurred at the external fuel elements surface, such as those promoted by corrosion processes. However, this test method cannot be used for detection of internal discontinuities at the tube walls. Sipping test allows the detection of fuel elements whose cladding has failed, but it is not able to determine the place where the discontinuity is located. On the other hand, eddy current testing, an electromagnetic nondestructive test method, allows the detection of discontinuities and monitoring their growth. In previous works, the application of eddy current testing to evaluate the AISI 304 cladding fuel elements of TRIGA IPR-R1 was studied. In this paper, it is proposed an initial study about the use of eddy current testing for detection and characterization of discontinuities in the aluminum 1100-F fuel elements cladding. The study includes the development of probes and the design and manufacture of reference standards. (author)

  10. Optical fiber current sensor with external conversion for measurements of low AC electric currents

    Science.gov (United States)

    Barczak, Kamil; Maźniewski, Krzysztof

    2017-08-01

    This article presents results of research on an optical fiber current sensor with external conversion (OFCS-EC), which was presented in article [1]. In this article the research is concentrated on an analysis of the sensor toward its application in power protection automation systems. For this purpose a busbar, designed for an operation in a current range up to 200 A, was selected. Such basbars are used in low voltage electric substations. A proper orientation of the OFCS-EC sensor head was chosen basing on calculations of a spatial magnetic field distribution round the busbar. Measurements were carried out in laboratory conditions. The sensor was placed in an alternating magnetic field generated by an air magnetic coil. A value of magnetic field induction generated in the coil corresponded to conditions round the busbar for given intensity of electric current conducting in it. Investigations presented in this paper are focused on checking whether a response signal of the OFCS-EC in conditions corresponding to the ones prevailing in an industrial environment. The results of these investigations have proven linearity of a response signal. Uncertainty of measurements of electric current was 18 A for current effective value 200 A.

  11. Digitally Synthesized Alternative Current Sinusoidal Waveform for Resistive Sensor Measurements

    Directory of Open Access Journals (Sweden)

    K. N. Trachanidis

    2011-01-01

    Full Text Available This paper presents a circuit that has the ability to provide a sinusoidal current waveform. The produced waveform is alternative,so it takes positive and negative values. This circuit comprises a microcontroller, a DAC with current outputand a fast electronic switch. The sine wave samples are stored in the microcontroller’s data memory and are applied to theDAC’s digital 8-bit input. The complementary output currents are connected alternatively through the electronic switch tothe ground. At pre-calculated timing the microcontroller changes the polarity of the switch, allowing the DAC’s output, asalternative current, to flow through the resistive sensor (load, ending through the switch to the ground. Another microcontrolleracting as data acquisition chip, at the positive peaks is sampling the voltage across the load. These measurements aretransferred through the serial port to a PC, where the resistance is calculated and presented on screen.

  12. Analysis of Dark Current in BRITE Nanostellite CCD Sensors

    Directory of Open Access Journals (Sweden)

    Adam Popowicz

    2018-02-01

    Full Text Available The BRightest Target Explorer (BRITE is the pioneering nanosatellite mission dedicated for photometric observations of the brightest stars in the sky. The BRITE charge coupled device (CCD sensors are poorly shielded against extensive flux of energetic particles which constantly induce defects in the silicon lattice. In this paper we investigate the temporal evolution of the generation of the dark current in the BRITE CCDs over almost four years after launch. Utilizing several steps of image processing and employing normalization of the results, it was possible to obtain useful information about the progress of thermal activity in the sensors. The outcomes show a clear and consistent linear increase of induced damage despite the fact that only about 0.14% of CCD pixels were probed. By performing the analysis of temperature dependencies of the dark current, we identified the observed defects as phosphorus-vacancy (PV pairs, which are common in proton irradiated CCD matrices. Moreover, the Meyer-Neldel empirical rule was confirmed in our dark current data, yielding E M N = 24.8 meV for proton-induced PV defects.

  13. Nutrient uplift in a cyclonic eddy increases diversity, primary productivity and iron demand of microbial communities relative to a western boundary current

    Directory of Open Access Journals (Sweden)

    Martina A. Doblin

    2016-04-01

    Full Text Available The intensification of western boundary currents in the global ocean will potentially influence meso-scale eddy generation, and redistribute microbes and their associated ecological and biogeochemical functions. To understand eddy-induced changes in microbial community composition as well as how they control growth, we targeted the East Australian Current (EAC region to sample microbes in a cyclonic (cold-core eddy (CCE and the adjacent EAC. Phototrophic and diazotrophic microbes were more diverse (2–10 times greater Shannon index in the CCE relative to the EAC, and the cell size distribution in the CCE was dominated (67% by larger micro-plankton $(\\geq 20\\lrm{\\mu }\\mathrm{m}$ ≥ 20 μ m , as opposed to pico- and nano-sized cells in the EAC. Nutrient addition experiments determined that nitrogen was the principal nutrient limiting growth in the EAC, while iron was a secondary limiting nutrient in the CCE. Among the diazotrophic community, heterotrophic NifH gene sequences dominated in the EAC and were attributable to members of the gamma-, beta-, and delta-proteobacteria, while the CCE contained both phototrophic and heterotrophic diazotrophs, including Trichodesmium, UCYN-A and gamma-proteobacteria. Daily sampling of incubation bottles following nutrient amendment captured a cascade of effects at the cellular, population and community level, indicating taxon-specific differences in the speed of response of microbes to nutrient supply. Nitrogen addition to the CCE community increased picoeukaryote chlorophyll a quotas within 24 h, suggesting that nutrient uplift by eddies causes a ‘greening’ effect as well as an increase in phytoplankton biomass. After three days in both the EAC and CCE, diatoms increased in abundance with macronutrient (N, P, Si and iron amendment, whereas haptophytes and phototrophic dinoflagellates declined. Our results indicate that cyclonic eddies increase delivery of nitrogen to the upper ocean to potentially

  14. Current Sensor Based Home Appliance and State of Appliance Recognition

    Science.gov (United States)

    Saitoh, Takeshi; Osaki, Tomoyuki; Konishi, Ryosuke; Sugahara, Kazunori

    This paper presents a current sensor-based home appliance and its state recognition method for intelligent outlets. Our system has three main functions: remote control, monitoring, and power supply schedule management. This research focuses particular on the monitoring function. To recognize the appliance and the state of the appliance, we extract ten features based on a measured current signal. In the experiment, we gather a number of signals with various appliances, and find that three features Irms, Iavg, and Ipeak yield valid recognition results of 84.3%, 86.4%, and 90.3% for classifying the state of the appliance into three categories. Moreover, sufficient recognition rates of 97.4%, 97.7%, and 99.0% are obtained by consideration of three candidates.

  15. Detailed magnetic model simulations of the H- injection chicane magnets for the CERN PS Booster Upgrade, including eddy currents and influence on beam dynamics

    CERN Document Server

    Benedetto, E; Borburgh, J; Carli, C; Martini, M; Forte, V

    2014-01-01

    The CERN PS Booster will be upgraded with an H- injection system. The chicanemagnets for the injection bump ramp-down in 5 ms and generate eddy currents in the inconel vacuum chamber which perturb the homogeneity of the magnetic field. The multipolar field components are extracted from 3D OPERA simulations and are included in the lattice model. The -beating correction is computed all along the ramp and complete tracking simulations including space-charge are performed to evaluate the impact of these perturbations and correction on beam dynamics.

  16. INFLUENCE OF VARIATIONS OF THE CONDUCTIVITY OF UPPER LAYER OF TWO-LAYER SAMPLE ON OF PHASE INTRODUCED ELECTROMOTIVE FORCE OF SUPERIMPOSED TRANSDUCER OF EDDY CURRENT THICKNESS METER

    Directory of Open Access Journals (Sweden)

    A. V. Chernyshev

    2017-01-01

    Full Text Available In carrying out eddy current thickness measurement of two-layer conductive objects one from the interfering factors is the presence of variations in the value of the electrical conductivity of the material of the upper layer (coating when moving from point to point on the surface of object of control or when passing from one object of control to another. The aim of this work is to evaluate the accuracy of determining the thickness of the conductive coating disposed on a conducting ferromagnetic basis, using the phase method of eddy current testing. The reason of the error is variation of the electrical conductivity of the material of coating.Determination of the error is based on calculations using known analytical expressions for the loop with current of sinusoidal form arranged over the infinite half space with a covering as a thin layer. Selected in calculating electromagnetic parameters of coating and substrate approximately correspond to the case -chromium layer on a nickel base. Calculations are performed for different frequencies of current passed through coil.It is shown that at reduction of frequency of the current passes through the coil the error is reduced. The value of the lowest possible operating frequency of the excitation current is determined by the condition of absence influence on the phase introduced into the superimposed transducer emf variations in the thickness of the basis.To reduce the indicated error it is proposed to determine, on the basis of phase method at a relatively high frequency transducer current excitation, conductivity of the material of coating. After this, at a low frequency excitation current and using phase method, the coating thickness is determined, taking into consideration the previously determined value of the conductivity of coating. Also discussed ways to improve the accuracy of phase measurements in the MHz region of the excitation current frequency. 

  17. Mobile mapping and eddy covariance flux measurements of NH3 emissions from cattle feedlots with a portable laser-based open-path sensor

    Science.gov (United States)

    Tao, L.; Sun, K.; Pan, D.; Golston, L.; Stanton, L. G.; Ham, J. M.; Shonkwiler, K. B.; Nash, C.; Zondlo, M. A.

    2014-12-01

    Ammonia (NH3) is the dominant alkaline species in the atmosphere and an important compound in the global nitrogen cycle. There is a large uncertainty in NH3 emission inventory from agriculture, which is the largest source of NH3, including livestock farming and fertilizer applications. In recent years, a quantum cascade laser (QCL)-based open-path sensor has been developed to provide high-resolution, fast-response and high-sensitivity NH3 measurements. It has a detection limit of 150 pptv with a sample rate up to 20 Hz. This sensor has been integrated into a mobile platform mounted on the roof of a car to perform measurement of multiple trace gases. We have also used the sensor for eddy covariance (EC) flux measurements. The mobile sensing method provides high spatial resolution and fast mapping of measured gases. Meanwhile, the EC flux method offers accurate flux measurements and resolves the diurnal variability of NH3emissions. During the DISCOVER-AQ and FRAPPÉ field campaigns in 2014, this mobile platform was used to study NH3 emissions from cattle feedlot near Fort Morgan, Colorado. This specific feedlot was mapped multiple times in different days to study the variability of its plume characteristics. At the same time, we set up another open-path NH3 sensor with LICOR open-path sensors to perform EC flux measurements of NH3, CH4 and CO2 simultaneously in the same cattle feedlot as shown in Fig. 1. NH3/CH4 emission flux ratio show a strong temperature dependence from EC flux measurements. The median value of measured NH3 and CH4 emission flux ratio is 0.60 ppmv/ppmv. In contrast, the median value of ΔNH3/ΔCH4 ratios measured from mobile platform is 0.53 ppmv/ppmv for the same farm. The combination of mobile mapping and EC flux measurements with the same open-path sensors greatly improves understanding of NH3 emissions both spatially and temporally.

  18. Profiling of Current Transients in Capacitor Type Diamond Sensors

    Directory of Open Access Journals (Sweden)

    Eugenijus Gaubas

    2015-06-01

    Full Text Available The operational characteristics of capacitor-type detectors based on HPHT and CVD diamond have been investigated using perpendicular and parallel injection of carrier domain regimes. Simulations of the drift-diffusion current transients have been implemented by using dynamic models based on Shockley-Ramo’s theorem, under injection of localized surface domains and of bulk charge carriers. The bipolar drift-diffusion regimes have been analyzed for the photo-induced bulk domain (packet of excess carriers. The surface charge formation and polarization effects dependent on detector biasing voltage have been revealed. The screening effects ascribed to surface charge and to dynamics of extraction of the injected bulk excess carrier domain have been separated and explained. The parameters of drift mobility of the electrons μe = 4000 cm2/Vs and holes μh = 3800 cm2/Vs have been evaluated for CVD diamond using the perpendicular profiling of currents. The coefficient of carrier ambipolar diffusion Da = 97 cm2/s and the carrier recombination lifetime τR,CVD ≌ 110 ns in CVD diamond were extracted by combining analysis of the transients of the sensor current and the microwave probed photoconductivity. The carrier trapping with inherent lifetime τR,HPHT ≌ 2 ns prevails in HPHT diamond.

  19. Effects of transient bottom water currents and oxygen concentrations on benthic exchange rates as assessed by eddy correlation measurements

    DEFF Research Database (Denmark)

    Holtappels, Moritz; Glud, Ronnie N.; Doris, Daphne

    2013-01-01

    Eddy correlation (EC) measurements in the benthic boundary layer (BBL) allow estimating benthic O2 uptake from a point distant to the sediment surface. This noninvasive approach has clear advantages as it does not disturb natural hydrodynamic conditions, integrates the flux over a large foot...... in the bottom water are in steady state, which is seldom the case in highly dynamic environments like coastal waters. Therefore, it is of great importance to estimate the error introduced by nonsteady state conditions. We investigated two cases of transient conditions. First, the case of transient O2...... concentrations was examined using the theory of shear flow dispersion. A theoretical relationship between the change of O2 concentrations and the induced vertical O2 flux is introduced and applied to field measurements showing that changes of 5–10 μM O2 h−1 result in transient EC-fluxes of 6–12 mmol O2 m−2 d−1...

  20. Design and Development of a Low-Cost Optical Current Sensor

    Directory of Open Access Journals (Sweden)

    Gaizka Durana

    2013-10-01

    Full Text Available In this paper we demonstrate the design of a low-cost optical current sensor. The sensor principle is the Faraday rotation of a light beam through a magneto-optical material, SF2, when a magnetic field is present. The prototype has a high sensitivity and a high linearity for currents ranging from 0 up to 800 A. The error of the optical fibre sensor is smaller than 1% for electric currents over 175 A.

  1. Current-Induced Transistor Sensorics with Electrogenic Cells

    Directory of Open Access Journals (Sweden)

    Peter Fromherz

    2016-04-01

    Full Text Available The concepts of transistor recording of electroactive cells are considered, when the response is determined by a current-induced voltage in the electrolyte due to cellular activity. The relationship to traditional transistor recording, with an interface-induced response due to interactions with the open gate oxide, is addressed. For the geometry of a cell-substrate junction, the theory of a planar core-coat conductor is described with a one-compartment approximation. The fast electrical relaxation of the junction and the slow change of ion concentrations are pointed out. On that basis, various recording situations are considered and documented by experiments. For voltage-gated ion channels under voltage clamp, the effects of a changing extracellular ion concentration and the enhancement/depletion of ion conductances in the adherent membrane are addressed. Inhomogeneous ion conductances are crucial for transistor recording of neuronal action potentials. For a propagating action potential, the effects of an axon-substrate junction and the surrounding volume conductor are distinguished. Finally, a receptor-transistor-sensor is described, where the inhomogeneity of a ligand–activated ion conductance is achieved by diffusion of the agonist and inactivation of the conductance. Problems with regard to a development of reliable biosensors are mentioned.

  2. The EMOSFET as an oxygen sensor: constant current potentiometry

    NARCIS (Netherlands)

    Hendrikse, J.; Olthuis, Wouter; Bergveld, Piet

    1999-01-01

    In a previous paper, a novel type of potentiometric dissolved oxygen sensor was introduced. The transduction principle of the sensor is based on the modulation of the work function of an iridium oxide film by the ratio of IrIII/IrIV oxide in the film. This ratio depends on the oxygen concentration

  3. A large-eddy simulation study of wake propagation and power production in an array of tidal-current turbines.

    Science.gov (United States)

    Churchfield, Matthew J; Li, Ye; Moriarty, Patrick J

    2013-02-28

    This paper presents our initial work in performing large-eddy simulations of tidal turbine array flows. First, a horizontally periodic precursor simulation is performed to create turbulent flow data. Then those data are used as inflow into a tidal turbine array two rows deep and infinitely wide. The turbines are modelled using rotating actuator lines, and the finite-volume method is used to solve the governing equations. In studying the wakes created by the turbines, we observed that the vertical shear of the inflow combined with wake rotation causes lateral wake asymmetry. Also, various turbine configurations are simulated, and the total power production relative to isolated turbines is examined. We found that staggering consecutive rows of turbines in the simulated configurations allows the greatest efficiency using the least downstream row spacing. Counter-rotating consecutive downstream turbines in a non-staggered array shows a small benefit. This work has identified areas for improvement. For example, using a larger precursor domain would better capture elongated turbulent structures, and including salinity and temperature equations would account for density stratification and its effect on turbulence. Additionally, the wall shear stress modelling could be improved, and more array configurations could be examined.

  4. The energy balance experiment EBEX-2000. Part II: Intercomparison of eddy-covariance sensors and post-field data processing methods

    NARCIS (Netherlands)

    Mauder, M.; Oncley, S.P.; Vogt, R.; Weidinger, T.; Ribeiro, L.; Bernhofer, C.; Foken, T.; Kohsiek, W.; Bruin, de H.A.R.; Liu, H.

    2007-01-01

    The eddy-covariance method is the primary way of measuring turbulent fluxes directly. Many investigators have found that these flux measurements often do not satisfy a fundamental criterion¿closure of the surface energy balance. This study investigates to what extent the eddy-covariance measurement

  5. Eddy current imaging. Simplifying the direct problem. Analysis of a 2D case with formulations; Imagerie par courants de Foucault. Le probleme direct simplifie. Formulations et etude d`un cas 2D

    Energy Technology Data Exchange (ETDEWEB)

    Spineanu, A.; Zorgati, R.

    1995-12-31

    Eddy current non-destructive testing is used by EDF to detect faults affecting conductive objects such as steam generator tubes. A new technique, known as eddy current imaging, is being developed to facilitate diagnosis in this context. The first stage in this work, discussed in the present paper, consists in solving the direct problem. This entails determining the measurable quantities, on the basis of a thorough knowledge of the material considered. This was done by formulating the direct problem in terms of eddy currents in general 3D geometry context, applying distribution theory and Maxwell equations. Since no direct problem code was available we resorted to simplified situations. Taking care not to interfere with previous developments or those to be attempted in an inversion context, we studied the case of a flaw affecting a 2D structure, illuminated by a plane wave type probe. For this configuration, we studied the exact model and compared results with those of a linearized simplified model. This study emphasizes the ill-posed situation of the eddy current inverse problem related with the severe electromagnetic field attenuation. This means that regularization of the inverse problem, although absolutely necessary, will not be sufficient. Owing to the simplicity of the models available and implemented during the inversion process, processing real data would not yet be possible. We must first focus all our efforts on the direct 3 D problem, in conformity with the requirements of the inverse procedure ad describing a realistic eddy current NDT situation. At the same time, consideration should be given to the design of a specific probe customized for eddy current imaging. (authors). 9 refs., 5 figs., 3 appends.

  6. Sensor Selection via Convex Optimization in Remote Contact-free Measurement of Currents

    OpenAIRE

    Ghasemifard, Fatemeh; Norgren, Martin

    2017-01-01

    The sensor positions have substantial effect on the accuracy of remote contact-free reconstruction of currents in power transmission lines from magnetic field data, measured by a set of sensors located under the conductors. By maximizing a performance metric, based on the Fisher information matrix, Nopt sensors are selected from N candidate sensors. The main optimization problem is changed to a convex optimization problem using a relaxation of the integer constraints. The result for optimized...

  7. Integration of the ICE 3's linear eddy-current brake in the infrastructure - technical aspects and operational experience; Integration der linearen Wirbelstrombremse des ICE 3 in die Infrastruktur - technische Aspekte und Betriebserfahrungen

    Energy Technology Data Exchange (ETDEWEB)

    Kunz, M. [Deutsche Bahn AG, Muenchen (Germany). DB-Systemtechnik; Graeber, J. [Deutsche Bahn AG, Minden (Germany). DB-Systemtechnik

    2004-08-01

    The first use of the linear eddy-current brake in a regular train service was on Deutsche Bahn's ICE 3 EMUs. The two big advantages of this brake technology are that it causes no wear and tear and it does not depend on the adhesion coefficients at the point of wheel/rail contact. The authors briefly outline the various development steps up until the time when the linear eddy current brake was fit for service. They then go on to discuss its interactions with the infrastructure. (orig.)

  8. Eddy-Kuroshio Interactions: Local and Remote Effects

    Science.gov (United States)

    Jan, Sen; Mensah, Vigan; Andres, Magdalena; Chang, Ming-Huei; Yang, Yiing Jang

    2017-12-01

    Quasi-geostrophic mesoscale eddies regularly impinge on the Kuroshio in the western North Pacific, but the processes underlying the evolution of these eddy-Kuroshio interactions have not yet been thoroughly investigated in the literature. Here this interaction is examined with results from a semi-idealized three-dimensional numerical model and observations from four pressure-sensor equipped inverted echo sounders (PIESs) in a zonal section east of Taiwan and satellite altimeters. Both the observations and numerical simulations suggest that, during the interaction of a cyclonic eddy with the Kuroshio, the circular eddy is deformed into an elliptic shape with the major axis in the northwest-southeast direction, before being dissipated; the poleward velocity and associated Kuroshio transport decrease and the sea level and pycnocline slopes across the Kuroshio weaken. In contrast, for an anticyclonic eddy during the eddy-Kuroshio interaction, variations in the velocity, sea level, and isopycnal depth are reversed; the circular eddy is also deformed to an ellipse but with the major axis parallel to the Kuroshio. The model results also demonstrate that the velocity field is modified first and consequently the SSH and isopycnal depth evolve during the interaction. Furthermore, due to the combined effect of impingement latitude and realistic topography, some eddy-Kuroshio interactions east of Taiwan are found to have remote effects, both in the Luzon Strait and on the East China Sea shelf northeast of Taiwan.Plain Language SummaryMesoscale eddies are everywhere in the ocean. These ocean swirls of either clockwise or counterclockwise spinning with diameter of about 100-300 km and rounding current speed of about 0.5 m/s, carrying energy and certain type of water mass, move westward and eventually reach the western boundary of each ocean. The evolution of these eddies and the interaction which occurs when they encounter the western boundary current, e.g. the Kuroshio in the

  9. Eddy Current Loss Induced in Aluminum Thermal Conduction Strips for ASPCS Coils Indirectly Cooled by Liquid Hydrogen through Thermo-siphon System

    Science.gov (United States)

    Ota, Narumi; Katsura, Masashi; Ando, Kennosuke; Takao, Tomoaki; Shintomi, Takakazu; Makida, Yasuhiro; Hamajima, Takataro; Tsuda, Makoto; Miyagi, Daisuke; Tsujigami, Hiroshi; Fujikawa, Shizuichi; Semba, Toshiaki; Iwaki, Katsuya

    To promote renewable energy sources, we proposed a new system called the Advanced Superconducting Power Conditioning System (ASPCS), which consists of Superconducting Magnetic Energy Storage-system (SMES), Electrolyzer, and Fuel Cell, and is also combined with a liquid hydrogen station for vehicles. The SMES plays a role to compensate the fast fluctuations generated by the renewable energies. In case of the ASPCS with a capacity of 5 MW, we designed the 50 MJ-class SMES composed of 4 solenoid coils. The winding of the solenoid coils is double pancake and a basic coil is 2 m in diameter and 0.5 m in height. Each SMES coil is wound with MgB2 conductor and indirectly cooled at 20 K by liquid hydrogen flowing through a thermo-siphon cooling system. Pure aluminum strips are inserted between the double-pancake coils and the pure aluminum plates gathering the strips lead to liquid hydrogen pipes. This scheme enables the strips and the plates to transfer the heat load in the coils to the cooling pipes and keep the coils at low temperature. On the other hand, we must consider that the strips generate eddy current loss which is strongly affected by a width of the strips. At the same time as the primary study of the SMES coils, we experimented on the thermo-siphon cooling system and investigated the relationship between the heat load and the heat extraction ability of the cooling system. The experiments showed that the cooling system could proficiently function. The estimation of eddy current loss from the particular cooling aluminum strips for the SMES in the ASPCS is reported with the results of the thermo-siphon driving experiment.

  10. Theoretic 3-D study of the high-frequency magnetic moment dynamics in thin ferromagnetic films with in-plane uniaxial anisotropy by considering eddy-current generation

    Energy Technology Data Exchange (ETDEWEB)

    Seemann, K., E-mail: klaus.seemann@kit.edu [Karlsruhe Institute of Technology KIT (Campus North), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany); Leiste, H.; Krueger, K. [Karlsruhe Institute of Technology KIT (Campus North), Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2012-06-15

    In the present paper, theoretic investigations of polarisation vector precession trajectories represented by a macro spin in ferromagnetic films with in-plane uniaxial anisotropy were realised. For this purpose, the Landau-Lifschitz-Gilbert differential equation (LLG) in combination with the Maxwell equations were solved for three dimensions by considering a linear progression of the magnetisation or polarisation with an external field. The frequency and time dependent polarisation trajectories illustrate how a magnetic moment precesses if effective damping and eddy-currents impacts its motion. For computation, typical parameter values like the saturation polarisation J{sub s}={mu}{sub 0}{center_dot}M{sub s}=1.4 T and in-plane uniaxial anisotropy {mu}{sub 0}{center_dot}H{sub u}=4.5 mT were employed. The main focus of simulation was on the variation of the effective damping parameter {alpha}{sub eff} between 0.01 and 0.05 and ferromagnetic film thickness t{sub m} between 200 nm and 1200 nm. The frequency-dependent calculations were carried out between 50 MHz and 6 GHz. The time-dependent simulations were done for a duration between 5 and 30 ns. - Highlights: Black-Right-Pointing-Pointer Frequency- and time domain solution of the LLG and Maxwell differential equation. Black-Right-Pointing-Pointer 3D magnetic moment or macro spin trajectories by eddy-current impact. Black-Right-Pointing-Pointer Progression of a magnetic excitation field in thin ferromagnetic films. Black-Right-Pointing-Pointer Transient response evaluation of uniform magnetic moments excited by an r.f. field.

  11. Fiber optic sensors current status and future possibilities

    CERN Document Server

    Ikezawa, Satoshi; Corres, Jesus

    2017-01-01

    This book describes important recent developments in fiber optic sensor technology and examines established and emerging applications in a broad range of fields and markets, including power engineering, chemical engineering, bioengineering, biomedical engineering, and environmental monitoring. Particular attention is devoted to niche applications where fiber optic sensors are or soon will be able to compete with conventional approaches. Beyond novel methods for the sensing of traditional parameters such as strain, temperature, and pressure, a variety of new ideas and concepts are proposed and explored. The significance of the advent of extended infrared sensors is discussed, and individual chapters focus on sensing at THz frequencies and optical sensing based on photonic crystal structures. Another important topic is the resonances generated when using thin films in conjunction with optical fibers, and the enormous potential of sensors based on lossy mode resonances, surface plasmon resonances, and long-range...

  12. The use of disjunct eddy sampling methods for the determination of ecosystem level fluxes of trace gases

    Directory of Open Access Journals (Sweden)

    A. A. Turnipseed

    2009-02-01

    Full Text Available The concept of disjunct eddy sampling (DES for use in measuring ecosystem-level micrometeorological fluxes is re-examined. The governing equations are discussed as well as other practical considerations and guidelines concerning this sampling method as it is applied to either the disjunct eddy covariance (DEC or disjunct eddy accumulation (DEA techniques. A disjunct eddy sampling system was constructed that could either be combined with relatively slow sensors (response time of 2 to 40 s to measure fluxes using DEC, or could also be used to accumulate samples in stable reservoirs for later laboratory analysis (DEA technique. Both the DEC and DEA modes of this sampler were tested against conventional eddy covariance (EC for fluxes of either CO2 (DEC or isoprene (DEA. Good agreement in both modes was observed relative to the EC systems. However, the uncertainty in a single DEA flux measurement was considerable (~40% due to both the reduced statistical sampling and the analytical precision of the concentration difference measurements. We have also re-investigated the effects of nonzero mean vertical wind velocity on accumulation techniques as it relates to our DEA measurements. Despite the higher uncertainty, disjunct eddy sampling can provide an alternative technique to eddy covariance for determining ecosystem-level fluxes for species where fast sensors do not currently exist.

  13. The use of disjunct eddy sampling methods for the determination of ecosystem level fluxes of trace gases

    Science.gov (United States)

    Turnipseed, A. A.; Pressley, S. N.; Karl, T.; Lamb, B.; Nemitz, E.; Allwine, E.; Cooper, W. A.; Shertz, S.; Guenther, A. B.

    2009-02-01

    The concept of disjunct eddy sampling (DES) for use in measuring ecosystem-level micrometeorological fluxes is re-examined. The governing equations are discussed as well as other practical considerations and guidelines concerning this sampling method as it is applied to either the disjunct eddy covariance (DEC) or disjunct eddy accumulation (DEA) techniques. A disjunct eddy sampling system was constructed that could either be combined with relatively slow sensors (response time of 2 to 40 s) to measure fluxes using DEC, or could also be used to accumulate samples in stable reservoirs for later laboratory analysis (DEA technique). Both the DEC and DEA modes of this sampler were tested against conventional eddy covariance (EC) for fluxes of either CO2 (DEC) or isoprene (DEA). Good agreement in both modes was observed relative to the EC systems. However, the uncertainty in a single DEA flux measurement was considerable (~40%) due to both the reduced statistical sampling and the analytical precision of the concentration difference measurements. We have also re-investigated the effects of nonzero mean vertical wind velocity on accumulation techniques as it relates to our DEA measurements. Despite the higher uncertainty, disjunct eddy sampling can provide an alternative technique to eddy covariance for determining ecosystem-level fluxes for species where fast sensors do not currently exist.

  14. A novel carbon nanotubefet based bulk built-in current sensor for ...

    Indian Academy of Sciences (India)

    This paper describes the new bulk current based built-in current sensor (BBICS) for the detection of single event upset (SEU) in CNTFET SRAM with less number of transistors compared to previous designs. The advantage of it is that its ability to detect low ranges of microcurrent. The complete circuit, both SRAM and Sensor ...

  15. Deadzones, Dying Eddies, and the Loop Current: Stability, Ventilation, and Heat Content from Buoyancy Glider Observations in the Northwest Gulf of Mexico in Spring and Summer 2015

    Science.gov (United States)

    DiMarco, S. F.; Knap, A. H.; Wang, Z.; Walpert, J.; Dreger, K.

    2016-02-01

    The northwestern Gulf of Mexico is host to a myriad of physical and biochemical processes, which govern the exchange and transport of material and volume between the coastal and offshore environments. We report on five G2 Slocum glider deployments in the northwestern Gulf during the spring and summer of 2015. The gliders were deployed in shallow (20 m) and deep (greater than 1000 m) water for a total of about 200 days. During this time, the gliders encountered a variety of environmental conditions that impact the circulation, biology, chemistry of the shelf and slope. The shallow gliders encountered coastal waters influenced by extensive flooding in terrestrial Texas that vertically stratified the water-column and was coincident with sub-pycnocline low dissolved oxygen concentration, at times below the hypoxic threshold of 2 mg/L, and elevated CDOM concentrations. These gliders also reveal high spatial variability with bottom boundary oxygen and biomass scales on the order of a few kilometers. The deep gliders were tasked to investigate shelf/slope exchange at two locations 94W and 91W. The western glider encountered a mature mesoscale circulation eddy that was actively weakening. The eastern glider simultaneously encountered a freshly separated Loop Current eddy. The vertical structure of hydrographic and dissolved oxygen parameters shows significant and distinguishable variability in each feature. The vertical structure of both features show significant departures from that which is expected based on sea surface height determined from satellite altimetry. Additionally, glider observations are compared to operational high-resolution regional numerical model output. These observations emphasize the importance of direct observations over satellite-derived products for applications that include upper ocean heat content for hurricane intensification and vertical mixing and ventilation of the oceanic interior.

  16. Non-contact current and voltage sensor having detachable housing incorporating multiple ferrite cylinder portions

    Energy Technology Data Exchange (ETDEWEB)

    Carpenter, Gary D.; El-Essawy, Wael; Ferreira, Alexandre Peixoto; Keller, Thomas Walter; Rubio, Juan C.; Schappert, Michael A.

    2016-04-26

    A detachable current and voltage sensor provides an isolated and convenient device to measure current passing through a conductor such as an AC branch circuit wire, as well as providing an indication of an electrostatic potential on the wire, which can be used to indicate the phase of the voltage on the wire, and optionally a magnitude of the voltage. The device includes a housing formed from two portions that mechanically close around the wire and that contain the current and voltage sensors. The current sensor is a ferrite cylinder formed from at least three portions that form the cylinder when the sensor is closed around the wire with a hall effect sensor disposed in a gap between two of the ferrite portions along the circumference to measure current. A capacitive plate or wire is disposed adjacent to, or within, the ferrite cylinder to provide the indication of the voltage.

  17. Experimental and theoretical analysis of an optical current sensor for high power systems

    Science.gov (United States)

    Brigida, A. C. S.; Nascimento, I. M.; Mendonça, S.; Costa, J. C. W. A.; Martinez, M. A. G.; Baptista, J. M.; Jorge, P. A. S.

    2013-03-01

    A magneto-optical sensor, using a dual quadrature polarimetric processing scheme, was evaluated for current metering and protection applications in high voltage lines. Sensor calibration and resolution were obtained in different operational conditions using illumination in the 1550-nm band. Results obtained indicated the feasibility of interrogating such sensor via the optical ground wire (OPGW) link installed in standard high power grids. The polarimetric bulk optical current sensor also was theoretically studied, and the effects of different sources of error considering practical deployment were evaluated. In particular, the interference from external magnetic fields in a tree-phase system was analyzed.

  18. Extraction: a system for automatic eddy current diagnosis of steam generator tubes in nuclear power plants; Extracsion: un systeme de controle automatique par courants de Foucault des tubes de generateurs de vapeur de centrales nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Georgel, B.; Zorgati, R.

    1994-12-31

    Improving speed and quality of Eddy Current non-destructive testing of steam generator tubes leads to automatize all processes that contribute to diagnosis. This paper describes how we use signal processing, pattern recognition and artificial intelligence to build a software package that is able to automatically provide an efficient diagnosis. (authors). 2 figs., 5 refs.

  19. Anthropogenic organochlorine compounds as potential tracers for regional water masses: A case study of estuarine plume, coastal eddy, wind-driven upwelling and long-range warm current.

    Science.gov (United States)

    Ya, Miaolei; Wu, Yuling; Li, Yongyu; Wang, Xinhong

    2017-03-01

    Water masses are the crucial factor driving the terrigenous anthropogenic organochlorine compounds (OCs) migration from the coast to open sea. Therefore, organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) were investigated in the Northern South China Sea (NSCS), where different types of water masses are generated by the East Asian summer monsoon: Pearl River estuary plume (PREP), Guangdong offshore eddy (GDEC), South China Sea warm current (SCSWC) and wind-driven upwelling current (WDUC). No discrepant distributions of OC concentrations were found in these water masses (p > 0.05). However, compositions and diagnostic ratios of HCHs, DDTs, trans- or cis-chlordane and PCBs could reflect the discrepancies in the input, transport and transformation of OCs caused by the hydrological characteristics of water masses, therefore, this allowing them to serve as potential tracers of regional water masses. In detail, α/γ-HCH and β-HCH percentages could indicate the weathered residue in the GDEC, long-range transport in the SCSWC, rapid photodegradation in the surface WDUC and biodegradation in the deep WDUC, respectively. The predominance of o, p'-DDT and p, p'-DDT could indicate fresh input in the PREP, GDEC and WDUC. DDT/DDTs of ratios erosion in the PREP. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Current Trends in Sensors Based on Conducting Polymer Nanomaterials

    Science.gov (United States)

    Yoon, Hyeonseok

    2013-01-01

    Conducting polymers represent an important class of functional organic materials for next-generation electronic and optical devices. Advances in nanotechnology allow for the fabrication of various conducting polymer nanomaterials through synthesis methods such as solid-phase template synthesis, molecular template synthesis, and template-free synthesis. Nanostructured conducting polymers featuring high surface area, small dimensions, and unique physical properties have been widely used to build various sensor devices. Many remarkable examples have been reported over the past decade. The enhanced sensitivity of conducting polymer nanomaterials toward various chemical/biological species and external stimuli has made them ideal candidates for incorporation into the design of sensors. However, the selectivity and stability still leave room for improvement. PMID:28348348

  1. Current Trends in Sensors Based on Conducting Polymer Nanomaterials

    Directory of Open Access Journals (Sweden)

    Hyeonseok Yoon

    2013-08-01

    Full Text Available Conducting polymers represent an important class of functional organic materials for next-generation electronic and optical devices. Advances in nanotechnology allow for the fabrication of various conducting polymer nanomaterials through synthesis methods such as solid-phase template synthesis, molecular template synthesis, and template-free synthesis. Nanostructured conducting polymers featuring high surface area, small dimensions, and unique physical properties have been widely used to build various sensor devices. Many remarkable examples have been reported over the past decade. The enhanced sensitivity of conducting polymer nanomaterials toward various chemical/biological species and external stimuli has made them ideal candidates for incorporation into the design of sensors. However, the selectivity and stability still leave room for improvement.

  2. Spintronic Memristor Based Temperature Sensor Design with CMOS Current Reference

    Science.gov (United States)

    2012-03-01

    studied. BJT transistor is usually favored by designers. The most popular method is utilizing the difference between base-emitter voltages of a...substrate BJT transistor to detect temperature changes [18][20]. To make up the non-perfect linearity of BJT transistor , many curvature correction...the traditional temperature sensors, the key components for temperature detection are p-n junction diode [25] or transistor [17], which have been well

  3. Control of AC–DC grid side converter with single AC current sensor

    Indian Academy of Sciences (India)

    Himanshu Misra

    2017-11-24

    Nov 24, 2017 ... Grid side converter; vector control; single current sensor; AC–DC conversion. 1. Introduction. Three-phase ... of sensors in any closed loop control. This will lead to primarily two main advantages: cost ... induction motor control was presented by Verma and group in [15]. In this paper, extended work of [14] is ...

  4. THE RATE OF CURRENT CHANGE DURING A SHORT CIRCUIT IN THE POWER CIRCUITS OF THE ELECTRIC ROLLING STOCK WITH REGARD TO EDDY CURRENTS

    Directory of Open Access Journals (Sweden)

    L. V. Dubinets

    2010-04-01

    Full Text Available In the article the issue of influence of vortical currents on rate of change of short circuit current is considered, a mathematical model for the calculation of short circuit currents in the traction mode in the power circuits of DC electric rolling stock is presented, and the research results are given.

  5. Summary of Current Radiometric Calibration Coefficients for Landsat MSS, TM, ETM+, and EO-1 ALI Sensors

    Science.gov (United States)

    Chander, Gyanesh; Markham, Brian L.; Helder, Dennis L.

    2009-01-01

    This paper provides a summary of the current equations and rescaling factors for converting calibrated Digital Numbers (DNs) to absolute units of at-sensor spectral radiance, Top-Of- Atmosphere (TOA) reflectance, and at-sensor brightness temperature. It tabulates the necessary constants for the Multispectral Scanner (MSS), Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Advanced Land Imager (ALI) sensors. These conversions provide a basis for standardized comparison of data in a single scene or between images acquired on different dates or by different sensors. This paper forms a needed guide for Landsat data users who now have access to the entire Landsat archive at no cost.

  6. Tunable three-axis magnetoresistance sensor with a spin-polarised current

    Science.gov (United States)

    Chang, Jui-Hang; Chang, Ching-Ray

    2015-10-01

    A three-axis magnetic tunnel junction sensor with three ferromagnetic layers to achieve a linear and hysteresis-free response is proposed and studied analytically. We show that the orientation of the easy axis of the sensor and the sensitivity are tunable by changing the density of a injected spin-polarised current. Additionally, the sensors integrated in a full Wheatstone bridge can have perpendicular and transverse sensing capability in different initial magnetisation arrangements. A value of 0.35% TMR/Oe is observed in sensing the perpendicular field. These findings indicate that a three-axis sensor can be fabricated more easily on a flat substrate.

  7. RBF-Neural Network Applied to the Quality Classification of Tempered 100Cr6 Steel Cams by the Multi-Frequency Nondestructive Eddy Current Testing

    Directory of Open Access Journals (Sweden)

    Víctor Martínez-Martínez

    2017-09-01

    Full Text Available This article proposes a Radial Basis Function Artificial Neural Network (RBF-ANN to classify tempered steel cams as correctly or incorrectly treated pieces by using multi-frequency nondestructive eddy current testing. Impedances at five frequencies between 10 kHz and 300 kHz were employed to perform the binary sorting. The ANalysis Of VAriance (ANOVA test was employed to check the significance of the differences between the impedance samples for the two classification groups. Afterwards, eleven classifiers were implemented and compared with one RBF-ANN classifier: ten linear discriminant analysis classifiers and one Euclidean distance classifier. When employing the proposed RBF-ANN, the best performance was achieved with a precision of 95% and an area under the Receiver Operating Characteristic (ROC curve of 0.98. The obtained results suggest RBF-ANN classifiers processing multi-frequency impedance data could be employed to classify tempered steel DIN 100Cr6 cams with a better performance than other classical classifiers.

  8. Theoretic 3-D study of the high-frequency magnetic moment dynamics in thin ferromagnetic films with in-plane uniaxial anisotropy by considering eddy-current generation

    Science.gov (United States)

    Seemann, K.; Leiste, H.; Krüger, K.

    2012-06-01

    In the present paper, theoretic investigations of polarisation vector precession trajectories represented by a macro spin in ferromagnetic films with in-plane uniaxial anisotropy were realised. For this purpose, the Landau-Lifschitz-Gilbert differential equation (LLG) in combination with the Maxwell equations were solved for three dimensions by considering a linear progression of the magnetisation or polarisation with an external field. The frequency and time dependent polarisation trajectories illustrate how a magnetic moment precesses if effective damping and eddy-currents impacts its motion. For computation, typical parameter values like the saturation polarisation Js=μ0·Ms=1.4 T and in-plane uniaxial anisotropy μ0·Hu=4.5 mT were employed. The main focus of simulation was on the variation of the effective damping parameter αeff between 0.01 and 0.05 and ferromagnetic film thickness tm between 200 nm and 1200 nm. The frequency-dependent calculations were carried out between 50 MHz and 6 GHz. The time-dependent simulations were done for a duration between 5 and 30 ns.

  9. Circular Array of Magnetic Sensors for Current Measurement: Analysis for Error Caused by Position of Conductor.

    Science.gov (United States)

    Yu, Hao; Qian, Zheng; Liu, Huayi; Qu, Jiaqi

    2018-02-14

    This paper analyzes the measurement error, caused by the position of the current-carrying conductor, of a circular array of magnetic sensors for current measurement. The circular array of magnetic sensors is an effective approach for AC or DC non-contact measurement, as it is low-cost, light-weight, has a large linear range, wide bandwidth, and low noise. Especially, it has been claimed that such structure has excellent reduction ability for errors caused by the position of the current-carrying conductor, crosstalk current interference, shape of the conduction cross-section, and the Earth's magnetic field. However, the positions of the current-carrying conductor-including un-centeredness and un-perpendicularity-have not been analyzed in detail until now. In this paper, for the purpose of having minimum measurement error, a theoretical analysis has been proposed based on vector inner and exterior product. In the presented mathematical model of relative error, the un-center offset distance, the un-perpendicular angle, the radius of the circle, and the number of magnetic sensors are expressed in one equation. The comparison of the relative error caused by the position of the current-carrying conductor between four and eight sensors is conducted. Tunnel magnetoresistance (TMR) sensors are used in the experimental prototype to verify the mathematical model. The analysis results can be the reference to design the details of the circular array of magnetic sensors for current measurement in practical situations.

  10. Electronic Energy Meter Based on a Tunnel Magnetoresistive Effect (TMR) Current Sensor

    National Research Council Canada - National Science Library

    Enrique García Vidal; Diego Ramírez Muñoz; Sergio Ivan Ravelo Arias; Jaime Sanchez Moreno; Susana Cardoso; Ricardo Ferreira; Paulo Freitas

    2017-01-01

    ...) electrical current sensor is presented. After its physical and electrical characterization, a wattmeter is developed to determine the active power delivered to a load from the AC 50/60 Hz mains line...

  11. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications

    National Research Council Canada - National Science Library

    Julien Perchoux; Adam Quotb; Reza Atashkhooei; Francisco J Azcona; Evelio E Ramírez-Miquet; Olivier Bernal; Ajit Jha; Antonio Luna-Arriaga; Carlos Yanez; Jesus Caum; Thierry Bosch; Santiago Royo

    2016-01-01

      Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics...

  12. Phenomenological modeling of eddy current signals with a view to characterizing steam generator tube flaws; Modelisation phenomenologique des signaux courants de Foucault en vue de la caracterisation des defauts des tubes de generateurs de vapeur

    Energy Technology Data Exchange (ETDEWEB)

    La, R

    1997-12-31

    This work deals with the eddy current non-destructive test ing. Its long-term goal is to design an `inverse model` for evaluating the geometry an d the dimensions of steam generator tube flaws from eddy current signals. The approach we adopted requires the preliminary knowledge of a `forward model` that estimates the eddy current signal knowing the geometry and the dimensions of the flaws. A quasi-exhaustive study of the existing forward models showed their inadequacy to solve the inverse problem. Hence, we proposed to build a general forward model, appropriate to the inversion. Using a parametric approach, this model is phenomenological, i.e. it is based on observations made from results of a finite element code. For each position of the coil, the proposed forward model fist discretized the eddy current distribution into `tubes of current`. A parametric description of the shape of these tubes is given according the system constituted of the coil and the tubes of current as a `multi-transformer`, their current signal, can then be deduced. The model was validated in the case of an axisymmetric configuration. Comparisons with both analytical and numerical models showed very good agreements. Then, the proposed model was applied to a three-dimensional configuration. Comparisons with experimental results are sufficiently conclusive to validate the approach to the construction of the phenomenological model. However, before envisaging the inverse problem, the computation time, still too long, ought to be reduced and the parametric description needs to be generalized to other three-dimensional configurations. (author). 92 refs.

  13. FARADAY PLASMA CURRENT SENSOR WITH COMPENSATION FOR RECIPROCAL BIREFRINGENCE INDUCED BY MECHANICALPERTURBATIONS

    Directory of Open Access Journals (Sweden)

    Y. O. Barmenkov

    2003-07-01

    Full Text Available A Faraday fiber-optic current sensor was employed to measure the tokamak plasma current. In order todecrease the influence of mechanical perturbations on the sensor sensitivity, a two-pass optical scheme witha variable Faraday mirror at the fiber end is proposed. A decrease, by two orders of magnitude, in theinfluence of the linear birefringence produced by an external piezoceramic fiber modulator was experimentallyobserved.

  14. Calibration Monitoring for Sensor Calibration Interval Extension: Gaps in the Current Science Base

    Energy Technology Data Exchange (ETDEWEB)

    Coble, Jamie B.; Ramuhalli, Pradeep; Meyer, Ryan M.; Hashemian, Hash; Shumaker, Brent; Cummins, Dara

    2012-10-09

    Currently in the United States, periodic sensor recalibration is required for all safety-related sensors, typically occurring at every refueling outage, and it has emerged as a critical path item for shortening outage duration in some plants. International application of calibration monitoring has shown that sensors may operate for longer periods within calibration tolerances. This issue is expected to also be important as the United States looks to the next generation of reactor designs (such as small modular reactors and advanced concepts), given the anticipated longer refueling cycles, proposed advanced sensors, and digital instrumentation and control systems. Online monitoring (OLM) can be employed to identify those sensors that require calibration, allowing for calibration of only those sensors that need it. The U.S. Nuclear Regulatory Commission (NRC) accepted the general concept of OLM for sensor calibration monitoring in 2000, but no U.S. plants have been granted the necessary license amendment to apply it. This paper summarizes a recent state-of-the-art assessment of online calibration monitoring in the nuclear power industry, including sensors, calibration practice, and OLM algorithms. This assessment identifies key research needs and gaps that prohibit integration of the NRC-approved online calibration monitoring system in the U.S. nuclear industry. Several technical needs were identified, including an understanding of the impacts of sensor degradation on measurements for both conventional and emerging sensors; the quantification of uncertainty in online calibration assessment; determination of calibration acceptance criteria and quantification of the effect of acceptance criteria variability on system performance; and assessment of the feasibility of using virtual sensor estimates to replace identified faulty sensors in order to extend operation to the next convenient maintenance opportunity.

  15. Using unsupervised neural networks for eddy currents signature discrimination: a prospective study; Perspective d`utilisation des reseaux de neurones non supervises en discrimination des signatures courants de Foucault

    Energy Technology Data Exchange (ETDEWEB)

    Grimaldi, V.

    1994-02-01

    This report describes an application of unsupervised neural networks for eddy currents Non Destructive Testing (NDT) inspection of steam generator tubes. As a matter of fact conventional neurocomputing techniques (multilayer perceptions) fail to achieve desired results because of the inherent lack of data and the slowly changing characteristics involved. This is an original neural approach to defect detection, characterized by two aspects: diagnosis is expressed in architectural terms and the potential advantages of using unsupervised neural techniques are systematically discussed. After briefly recalling the context and origin of the study, we present the framework of the Kohonen self organizing maps within the proposed diagnosis architecture. We then show how we intend to use them for sound/unsound discrimination compliant with eddy currents NDT requirements. Preliminary results are presented in the last part of the report. They seem confirm that this new approach is worth being more deeply investigated. (author). 13 figs., 17 refs., 3 annexes.

  16. Image analysis from surface scanning with an absolute eddy current coil; Analyse d`images obtenues par balayage de surface avec un capteur ponctuel courants de Foucault

    Energy Technology Data Exchange (ETDEWEB)

    Attaoui, P.

    1994-10-19

    The aim of this work is to implement processing and analysis tools applied to eddy current imaging. These cartographies are issued from steam generator tubes testing using an absolute coil. The first is to eliminate the perturbations due to probe lift-off changes which generate low frequency oscillations on the image. The principle of the processing is to rebuild a complete surface of the noise using only the points around the defect area. The geometric origin of these perturbations led to a model based on sinusoidal functions. The method consists of gradually decomposing the image into a sum of basic sinusoidal surfaces. In order to take into account all kind of cartographies (especially rolling zone) some preprocessing must be applied. The results obtained with this `cartography flattening`are satisfactory and the phase of analysis could begin with good condition of signal ratio. The second part of this work dealt with the choice and the perfection of image processing tools which would fit the most with the defect characterization. The aim of this characterization is to give the orientation and main size of the detected defect. A morphological skeleton representation has been chosen to illustrate the defect architecture and to allow sizing. A set of tools has been elaborated to obtain an (automatic) processing according to threshold. The results for single defect are satisfactory since the sizing error is around {+-} 25% and orientation is nearly always correctly given. The processing for area with several defects is more complex and new complementary research directions are proposed. (author).

  17. Eddy County Current Area Landmark

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The TIGER/Line Files are shapefiles and related database files (.dbf) that are an extract of selected geographic and cartographic information from the U.S. Census...

  18. Eddy County Current Point Landmarks

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The TIGER/Line Files are shapefiles and related database files (.dbf) that are an extract of selected geographic and cartographic information from the U.S. Census...

  19. 3D, Flash, Induced Current Readout for Silicon Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Parker, Sherwood I. [Univ. of Hawaii, Honolulu, HI (United States)

    2014-06-07

    A new method for silicon microstrip and pixel detector readout using (1) 65 nm-technology current amplifers which can, for the first time with silicon microstrop and pixel detectors, have response times far shorter than the charge collection time (2) 3D trench electrodes large enough to subtend a reasonable solid angle at most track locations and so have adequate sensitivity over a substantial volume of pixel, (3) induced signals in addition to, or in place of, collected charge

  20. Smartphone Applications with Sensors Used in a Tertiary Hospital—Current Status and Future Challenges

    Directory of Open Access Journals (Sweden)

    Yu Rang Park

    2015-04-01

    Full Text Available Smartphones have been widely used recently to monitor heart rate and activity, since they have the necessary processing power, non-invasive and cost-effective sensors, and wireless communication capabilities. Consequently, healthcare applications (apps using smartphone-based sensors have been highlighted for non-invasive physiological monitoring. In addition, several healthcare apps have received FDA clearance. However, in spite of their potential, healthcare apps with smartphone-based sensors are mostly used outside of hospitals and have not been widely adopted for patient care in hospitals until recently. In this paper, we describe the experience of using smartphone apps with sensors in a large medical center in Korea. Among >20 apps developed in our medical center, four were extensively analyzed (“My Cancer Diary”, “Point-of-Care HIV Check”, “Blood Culture” and “mAMIS”, since they use smartphone-based sensors such as the camera and barcode reader to enter data into the electronic health record system. By analyzing the usage patterns of these apps for data entry with sensors, the current limitations of smartphone-based sensors in a clinical setting, hurdles against adoption in the medical center, benefits of smartphone-based sensors and potential future research directions could be evaluated.

  1. Smartphone applications with sensors used in a tertiary hospital-current status and future challenges.

    Science.gov (United States)

    Park, Yu Rang; Lee, Yura; Lee, Guna; Lee, Jae Ho; Shin, Soo-Yong

    2015-04-27

    Smartphones have been widely used recently to monitor heart rate and activity, since they have the necessary processing power, non-invasive and cost-effective sensors, and wireless communication capabilities. Consequently, healthcare applications (apps) using smartphone-based sensors have been highlighted for non-invasive physiological monitoring. In addition, several healthcare apps have received FDA clearance. However, in spite of their potential, healthcare apps with smartphone-based sensors are mostly used outside of hospitals and have not been widely adopted for patient care in hospitals until recently. In this paper, we describe the experience of using smartphone apps with sensors in a large medical center in Korea. Among >20 apps developed in our medical center, four were extensively analyzed ("My Cancer Diary", "Point-of-Care HIV Check", "Blood Culture" and "mAMIS"), since they use smartphone-based sensors such as the camera and barcode reader to enter data into the electronic health record system. By analyzing the usage patterns of these apps for data entry with sensors, the current limitations of smartphone-based sensors in a clinical setting, hurdles against adoption in the medical center, benefits of smartphone-based sensors and potential future research directions could be evaluated.

  2. Current Fluctuation Measurements of Amperometric Gas Sensors Constructed with Three Different Technology Procedures

    Directory of Open Access Journals (Sweden)

    Sedlak Petr

    2016-12-01

    Full Text Available Electrochemical amperometric gas sensors represent a well-established and versatile type of devices with unique features: good sensitivity and stability, short response/recovery times, and low power consumption. These sensors operate at room temperature, and therefore have been applied in monitoring air pollutants and detection of toxic and hazardous gases in a number of areas. Some drawbacks of classical electrochemical sensors are overcome by the solid polymer electrolyte (SPE based on ionic liquids. This work presents evaluation of an SPE-based amperometric sensor from the point of view of current fluctuations. The sensor is based on a novel three-electrode sensor platform with solid polymer electrolytes containing ionic liquid for detection of nitrogen dioxide − a highly toxic gas that is harmful to the environment and presenting a possible threat to human health even at low concentrations. The paper focuses on using noise measurement (electric current fluctuation measurement for evaluation of electrochemical sensors which were constructed by different fabrication processes: (i lift-off and drop-casting technology, (ii screen printing technology on a ceramic substrate and (iii screen printing on a flexible substrate.

  3. High Voltage Coil Current Sensor for DC-DC Converters Employing DDCC

    Directory of Open Access Journals (Sweden)

    M. Drinovsky

    2015-12-01

    Full Text Available Current sensor is an integral part of every switching converter. It is used for over-current protection, regulation and in case of multiphase converters for balancing. A new high voltage current sensor for coil-based current sensing in DC-DC converters is presented. The sensor employs DDCC with high voltage input stage and gain trimming. The circuit has been simulated and implemented in 0.35 um BCD technology as part of a multiphase DC-DC converter where its function has been verified. The circuit is able to sustain common mode voltage on the input up to 40 V, it occupies 0.387*0.345 mm2 and consumes 3.2 mW typically.

  4. Development of Fault Detection System using Wavelength Division Multiplexing Transmission of Optical Fiber Current Sensor

    Science.gov (United States)

    Kayaki, Masahiro; Hirata, Toshinari; Kurosawa, Kiyoshi; Kondo, Reishi; Yamada, Toshiharu; Itakura, Eiji

    A fault detection system is applied to power lines consisting of both overhead power line and underground power cable in order to detect a fault on the underground power cable section and prevent the automatic reclosing. The fault detection system using optical fiber current sensor has two subjects. The fist subject is that we have to use wound-type current transformer together, when applying the fault detection system to single-core underground power cable. The second subject is that we are not able to detect three-phase short-circuit fault in using the fault detection system. This paper describes that we developed a new fault detection system using optical fiber current sensor by applying the multiplex transmission technology of optical fiber current sensor signal in order to solve these subjects.

  5. Detection of current-driven magnetic domains in [Co/Pd] nanowire by tunneling magnetoresistive sensor

    Science.gov (United States)

    Okuda, Mitsunobu; Miyamoto, Yasuyoshi; Miyashita, Eiichi; Saito, Nobuo; Hayashi, Naoto; Nakagawa, Shigeki

    2015-05-01

    Current-driven magnetic domain walls in magnetic nanowires have attracted a great deal of interest in terms of both physical studies and engineering applications. The anomalous Hall effect measurement is widely used for detecting the magnetization direction of current-driven magnetic domains in a magnetic nanowire. However, the problem with this measurement is that the detection point for current-driven domain wall motion is fixed at only the installed sensing wire across the specimen nanowire. A potential solution is the magnetic domain scope method, whereby the distribution of the magnetic flux leaking from the specimen can be analyzed directly by contact-scanning a tunneling magnetoresistive field sensor on a sample. In this study, we fabricated specimen nanowires consisting of [Co (0.3)/Pd (1.2)]21/Ta(3) films (units in nm) with perpendicular magnetic anisotropy on Si substrates. A tunneling magnetoresistive sensor was placed on the nanowire surface and a predetermined current pulse was applied. Real-time detection of the current-driven magnetic domain motion was successful in that the resistance of the tunneling magnetoresistive sensor was changed with the magnetization direction beneath the sensor. This demonstrates that magnetic domain detection using a tunneling magnetoresistive sensor is effective for the direct analysis of micro magnetic domain motion.

  6. 49 CFR Appendix C to Part 180 - Eddy Current Examination With Visual Inspection for DOT 3AL Cylinders Manufactured of Aluminum...

    Science.gov (United States)

    2010-10-01

    ... for DOT 3AL Cylinders Manufactured of Aluminum Alloy 6351-T6 C Appendix C to Part 180 Transportation... Cylinders Manufactured of Aluminum Alloy 6351-T6 1. Examination Procedure. Each facility performing eddy... ring and probe for each DOT-3AL cylinder manufactured of aluminum alloy 6351-T6 to be inspected must be...

  7. Flame Propagation Through Swirling Eddys, A Recursive Pattern

    CERN Document Server

    Ashurst, W T

    1993-01-01

    Abstract: Computed flame motion through and between swirling eddys exhibits a maximum advancement rate which is related to the time duration of flame motion between eddys. This eddy spatial structure effect upon the apparent turbulent flame speed appears to be similar to the square-root dependence observed in wrinkled flamelet data. The rate-limiting behavior at one eddy length-scale can be removed by inclusion of smaller eddys which reside between the larger eddys. This large-eddy, small-eddy concept yields a recursion relation and repeated functional iteration can be done to approximate a desired flame speed relation. As an example, an iteration to produce $S_T Currently, the iteration process is a post-diction of flame speed, but if a universality can be developed, then a predictive theory of turbulent flame propagation might be achieved.

  8. The structure of temperature field in mesoscale eddies at the surface of the ocean in the Drake Passage.

    Science.gov (United States)

    Gritsenko, Alexander; Tarakanov, Roman

    2017-04-01

    The study of mesoscale eddies of the Antarctic Circumpolar Current (ACC) were performed on the basis of satellite data on the Absolute Dynamic Topography (ADT) produced by Ssalto/Duacs and distributed by Aviso, with support from Cnes (http://www.aviso.altimetry.fr/duacs/), and data on the ocean surface temperature (SST) of the Australian Centre of Weather and Climate research CAWCR (The Centre for Australian Weather and Climate research), calculated in the framework of the GAMSSA project (Global Australian Multi-Sensor SST Analysis, http://data.nodc.noaa.gov/las/getUI .do?dsid = id-c80878d11f & varid = analysed_sst-id-c80878d11f & auto = true/). We developed an algorithm and implemented a program for detection and mapping of cyclonic and anticyclonic mesoscale (synoptic) eddies in the ADT field for arbitrary day of the 19-year series of satellite observations. Preliminary results of the parameters and spatial distribution of mesoscale eddies in the region of the Drake Passage were obtained. The main part of eddies with different signs is associated with meandering jets and fronts of the ACC. To study the structure of the eddy surface temperature the eddy contours in the ADT field were mapped in the field of satellite SST for the same dates as the ADT data. Isotherms in cyclones and anticyclones reveal asymmetrical distribution of temperature. In the eastern (usually front) part of the cyclonic eddy, where the water transfer is directed from the low latitudes (clockwise in the Southern Hemisphere) to the high latitudes, the temperature is higher, and in the west (usually rear) part, where the water transfer is directed from high to low latitudes, it is lower. At the same time, the isotherms in cyclonic eddies deflected up in the form of domes and oriented to the northern or north-eastern direction. In the anticyclones, on the contrary, the isotherms deflected down in the form of cups and oriented mainly to the south. It should be noted that many of natural processes

  9. Northern Hemisphere Atmospheric Transient Eddy Fluxes from the MERRA and Their Co-variability with Ocean Frontal Variability near the Western Boundary Current Regions

    Science.gov (United States)

    Kwon, Y.-O.; Joyce, T. M.

    2012-04-01

    Time series of winter (January-March) meridional transient eddy heat and moisture fluxes ( and ) for 1979-2009 in two separate frequency bands, i.e. the synoptic (2-8 days) and intra-seasonal (8-90 days), are calculated for the whole Northern Hemisphere based on daily atmospheric variables from the NASA Modern Era Retrospective-analysis for Research and Applications (MERRA) at 1/2 degrees latitude by 2/3 degrees longitude resolution. The climatological mean transient eddy fluxes in two frequency bands exhibit markedly distinct spatial patterns. The synoptic transient eddy fluxes show storm-track variability, of which maxima are co-located with the Gulf Stream and the Kuroshio-Oyashio Extensions, respectively in each basin. On the other hand, the intra-seasonal transient eddy fluxes exhibit maxima co-located with the major orography, e.g. the Rockies. In a vertically and zonally integrated poleward heat transport sense, the maximum heat transports in the two frequency bands are similar, while the sensible heat fluxes are twice greater than the latent heat fluxes. In addition, co-variability between the meridional transient eddy heat and moisture fluxes and their divergence in the Northern Hemisphere atmosphere and the variability in the position of ocean fronts associated with the Kuroshio Extension, Oyashio Extension and Gulf Stream is examined with a focus on the interannual to decadal time scale. Statistically significant correlations are found between the as well as and the ocean fronts from the surface up to 250 hPa for all three ocean fronts. The co-variability explains approximately half of the interannual and longer variance in the synoptic band, while only ~20 % for the intra-seasonal band.

  10. A Current Sensor Based on the Giant Magnetoresistance Effect: Design and Potential Smart Grid Applications

    Directory of Open Access Journals (Sweden)

    Shan X. Wang

    2012-11-01

    Full Text Available Advanced sensing and measurement techniques are key technologies to realize a smart grid. The giant magnetoresistance (GMR effect has revolutionized the fields of data storage and magnetic measurement. In this work, a design of a GMR current sensor based on a commercial analog GMR chip for applications in a smart grid is presented and discussed. Static, dynamic and thermal properties of the sensor were characterized. The characterizations showed that in the operation range from 0 to ±5 A, the sensor had a sensitivity of 28 mV·A−1, linearity of 99.97%, maximum deviation of 2.717%, frequency response of −1.5 dB at 10 kHz current measurement, and maximum change of the amplitude response of 0.0335%·°C−1 with thermal compensation. In the distributed real-time measurement and monitoring of a smart grid system, the GMR current sensor shows excellent performance and is cost effective, making it suitable for applications such as steady-state and transient-state monitoring. With the advantages of having a high sensitivity, high linearity, small volume, low cost, and simple structure, the GMR current sensor is promising for the measurement and monitoring of smart grids.

  11. A current sensor based on the giant magnetoresistance effect: design and potential smart grid applications.

    Science.gov (United States)

    Ouyang, Yong; He, Jinliang; Hu, Jun; Wang, Shan X

    2012-11-09

    Advanced sensing and measurement techniques are key technologies to realize a smart grid. The giant magnetoresistance (GMR) effect has revolutionized the fields of data storage and magnetic measurement. In this work, a design of a GMR current sensor based on a commercial analog GMR chip for applications in a smart grid is presented and discussed. Static, dynamic and thermal properties of the sensor were characterized. The characterizations showed that in the operation range from 0 to ±5 A, the sensor had a sensitivity of 28 mV·A(-1), linearity of 99.97%, maximum deviation of 2.717%, frequency response of −1.5 dB at 10 kHz current measurement, and maximum change of the amplitude response of 0.0335%·°C(-1) with thermal compensation. In the distributed real-time measurement and monitoring of a smart grid system, the GMR current sensor shows excellent performance and is cost effective, making it suitable for applications such as steady-state and transient-state monitoring. With the advantages of having a high sensitivity, high linearity, small volume, low cost, and simple structure, the GMR current sensor is promising for the measurement and monitoring of smart grids.

  12. A Review of Current Neuromorphic Approaches for Vision, Auditory, and Olfactory Sensors.

    Science.gov (United States)

    Vanarse, Anup; Osseiran, Adam; Rassau, Alexander

    2016-01-01

    Conventional vision, auditory, and olfactory sensors generate large volumes of redundant data and as a result tend to consume excessive power. To address these shortcomings, neuromorphic sensors have been developed. These sensors mimic the neuro-biological architecture of sensory organs using aVLSI (analog Very Large Scale Integration) and generate asynchronous spiking output that represents sensing information in ways that are similar to neural signals. This allows for much lower power consumption due to an ability to extract useful sensory information from sparse captured data. The foundation for research in neuromorphic sensors was laid more than two decades ago, but recent developments in understanding of biological sensing and advanced electronics, have stimulated research on sophisticated neuromorphic sensors that provide numerous advantages over conventional sensors. In this paper, we review the current state-of-the-art in neuromorphic implementation of vision, auditory, and olfactory sensors and identify key contributions across these fields. Bringing together these key contributions we suggest a future research direction for further development of the neuromorphic sensing field.

  13. MOS-FET as a Current Sensor in Power Electronics Converters

    OpenAIRE

    Rok Pajer; Miro Milanoviĉ; Branko Premzel; Miran Rodiĉ

    2015-01-01

    This paper presents a current sensing principle appropriate for use in power electronics’ converters. This current measurement principle has been developed for metal oxide semiconductor field effect transistor (MOS-FET) and is based on U D S voltage measurement. In practice, shunt resistors and Hall effect sensors are usually used for these purposes, but the presented principle has many advantages. There is no need for additional circuit elements within high current paths, causing parasitic i...

  14. Design, Fabrication and Temperature Sensitivity Testing of a Miniature Piezoelectric-Based Sensor for Current Measurements

    Directory of Open Access Journals (Sweden)

    Steven B. Lao

    2014-07-01

    Full Text Available Grid capacity, reliability, and efficient distribution of power have been major challenges for traditional power grids in the past few years. Reliable and efficient distribution within these power grids will continue to depend on the development of lighter and more efficient sensing units with lower costs in order to measure current and detect failures across the grid. The objective of this paper is to present the development of a miniature piezoelectric-based sensor for AC current measurements in single conductors, which are used in power transmission lines. Additionally presented in this paper are the thermal testing results for the sensor to assess its robustness for various operating temperatures.

  15. Magnetic Field Sensors Based on Giant Magnetoresistance (GMR Technology: Applications in Electrical Current Sensing

    Directory of Open Access Journals (Sweden)

    Càndid Reig

    2009-10-01

    Full Text Available The 2007 Nobel Prize in Physics can be understood as a global recognition to the rapid development of the Giant Magnetoresistance (GMR, from both the physics and engineering points of view. Behind the utilization of GMR structures as read heads for massive storage magnetic hard disks, important applications as solid state magnetic sensors have emerged. Low cost, compatibility with standard CMOS technologies and high sensitivity are common advantages of these sensors. This way, they have been successfully applied in a lot different environments. In this work, we are trying to collect the Spanish contributions to the progress of the research related to the GMR based sensors covering, among other subjects, the applications, the sensor design, the modelling and the electronic interfaces, focusing on electrical current sensing applications.

  16. An Intrinsic Fiber-Optic Sensor for Structure Lightning Current Measurement

    Science.gov (United States)

    Nguyen, Truong X.; Ely, Jay J.; Szatkowski, George N.; Mata, Carlos T.; Mata, Angel. G.; Snyder, Gary P.

    2014-01-01

    An intrinsic optical-fiber sensor based on Faraday Effect is developed that is highly suitable for measuring lightning current on aircraft, towers and complex structures. Originally developed specifically for aircraft installations, it is light-weight, non-conducting, structure conforming, and is immune to electromagnetic interference, hysteresis and saturation. It can measure total current down to DC. When used on lightning towers, the sensor can help validate other sensors and lightning detection network measurements. Faraday Effect causes light polarization to rotate when the fiber is exposed to a magnetic field in the direction of light propagation. Thus, the magnetic field strength can be determined from the light polarization change. By forming closed fiber loops and applying Ampere's law, measuring the total light rotation yields the total current enclosed. A broadband, dual-detector, reflective polarimetric scheme allows measurement of both DC component and AC waveforms with a 60 dB dynamic range. Two systems were built that are similar in design but with slightly different sensitivities. The 1310nm laser system can measure 300 A - 300 kA, and has a 15m long sensing fiber. It was used in laboratory testing, including measuring current on an aluminum structure simulating an aircraft fuselage or a lightning tower. High current capabilities were demonstrated up to 200 kA at a lightning test facility. The 1550nm laser system can measure 400 A - 400 kA and has a 25m fiber length. Used in field measurements, excellent results were achieved in the summer of 2012 measuring rocket-triggered lightning at the International Center for Lightning Research and Testing (ICLRT), Camp Blanding, Florida. In both systems increased sensitivity can be achieved with multiple fiber loops. The fiber optic sensor provides many unique capabilities not currently possible with traditional sensors. It represents an important new tool for lightning current measurement where low weight

  17. High frequency current sensors using the Faraday effect in optical fibers

    Energy Technology Data Exchange (ETDEWEB)

    Cernosek, R.W. [Sandia National Labs., Albuquerque, NM (United States). Microsensor Research and Development Dept.

    1994-09-01

    This study investigates the high frequency response of Faraday effect optical fiber current sensors that are bandwidth-limited by the transit time of the light in the fiber. Mathematical models were developed for several configurations of planar (collocated turns) and travelling wave (helical turns) singlemode fiber sensor coils, and experimental measurements verified the model predictions. High frequency operation above 500 MHz, with good sensitivity, was demonstrated for several current sensors; this frequency region was not previously considered accessible by fiber devices. Planar fiber coils in three configurations were investigated: circular cross section with the conductor centered coaxially; circular cross section with the conductor noncentered; and noncircular cross section with arbitrary location of the conductor. The helical travelling wave fiber coils were immersed in the dielectric of a coaxial transmission line to improve velocity phase matching between the field and light. Three liquids (propanol, methanol, and water) and air were used as transmission line dielectric. Complete models, which must account for liquid dispersion and waveguide dispersion from the multilayer dielectric in the transmission line, were developed to describe the Faraday response of the travelling wave sensors. Other travelling wave current sensors with potentially greater Faraday sensitivity, wider bandwidth and smaller size are investigated using the theoretical models developed for the singlemode fibers coils.

  18. Design and optimization of the low frequency eddy current technique for the volumetric inspection of austenitic small diameter tubes with a wall thickness up to 12 mm; Auslegung und Optimierung des Niederfrequenz-Wirbelstrom-Verfahrens fuer die volumetrische Pruefung von austenitischen Neben- und Kleinleitungen mit Wandstaerken bis 12 mm

    Energy Technology Data Exchange (ETDEWEB)

    Becker, R.; Bessert, S.; Disque, M.; Weiss, R. [Fraunhofer-Institut fuer Zerstoerungsfreie Pruefverfahren, Saarbruecken (Germany)

    1998-11-01

    The low-frequency eddy current technique discussed is a suitable external inspection technique detecting defects at the inner walls of small-diameter tubes and measuring their depths via the ligament. A testing system with optimized sensor lus software for image recording, evaluation, display and documentation is available. The current state of development of the system permits detection and measurement of defects up to 20 mm in size in austenitic inner walls 12.5 mm thick down to a depth of 3 mm. This applies both to the homogenous base metal and the weld with {delta} ferrite. (orig./CB) [Deutsch] Das vorgestellte Niederfrequenz-Wirbelstrom-Verfahren ist geeignet, bei Pruefung von aussen Fehler an der Innenseite von Klein- und Nebenleitungen nachzuweisen und ueber das Ligament deren Tiefe zu bestimmen. Ein entsprechendes Pruefsystem mit optimiertem Sensor und der Software zur Aufnahme, Auswertung, Darstellung und Dokumentation der Wirbelstrom-Urdaten steht zur Verfuegung. Beim jetzigen Entwicklungsstand liegt die Nachweisgrenze fuer einen 20 mm langen Innenfehler in einer 12.5 mm dicken austenitischen Wandung bei einer Fehlertiefe von 3 mm. Dies gilt sowohl fuer den homogenen Grundwerkstoff als auch fuer Schweissgefuege mit {delta}-Ferrit. (orig./MM)

  19. Improvements in separation of non-ferrous scrap metals using an electromagnetic sensor

    NARCIS (Netherlands)

    Mesina, M.B.; De Jong, T.P.R.; Dalmijn, W.L.

    2003-01-01

    This article describes a new method for identification and separation of non-ferrous scrap metals using an electromagnetic sensor that is based on the eddy current principle. The electromagnetic sensor (EMS) is a prototype system that has been developed by Delft University of Technology in

  20. Fault Reconstruction Based on Sliding Mode Observer for Current Sensors of PMSM

    Directory of Open Access Journals (Sweden)

    Changfan Zhang

    2016-01-01

    Full Text Available This paper deals with a method of phase current sensor fault reconstruction for permanent magnet synchronous motor (PMSM drives. A new state variable is introduced so that an augmented system can be constructed to treat PMSM sensor faults as actuator faults. This method uses the PMSM two-phase stationary reference frame fault model and a sliding mode variable structure observer to reconstruct fault signals. A logic algorithm is built to isolate and identify the faulty sensor for a stator phase current fault after reconstructing the two-phase stationary reference frame fault signals, which allows the phase fault signals to be reconstructed. Simulation results are presented to illustrate the functionality of the theoretical developments.

  1. Phytoplankton size structure in the southern Bay of Bengal modified by the Summer Monsoon Current and associated eddies: Implications on the vertical biogenic flux..

    Digital Repository Service at National Institute of Oceanography (India)

    Jyothibabu, R.; Vinayachandran, P. N.; Madhu, N.V.; Robin, R.S.; Karman, C.; Jagadeesan, L.; Anjusha, A.

    in the region significantly influenced by the SMC- associated anti-cyclonic eddy (location12 and 13). In general, the contribution of smaller phytoplankton size fractions (pico and nano plankton; <20 µm) to the total chlorophyll biomass was predominant... concentration, the locations with higher percentage contribution from the larger phytoplankton was placed in the right hand side of the Triplot whereas locations with smaller phytoplankton fractions (pico- and nano) making the maximum chlorophyll contribution...

  2. Final Report Providing the Design for Low-Cost Wireless Current Transducer and Electric Power Sensor Prototype

    Energy Technology Data Exchange (ETDEWEB)

    Kintner-Meyer, Michael CW; Burghard, Brion J.; Reid, Larry D.

    2005-01-31

    This report describes the design and development of a wireless current transducer and electric power sensor prototype. The report includes annotated schematics of the power sensor circuitry and the printed circuit board. The application program used to illustrate the functionality of the wireless sensors is described in this document as well.

  3. Sensor technologies aiming at fall prevention in institutionalized old adults : A. synthesis of current knowledge

    NARCIS (Netherlands)

    Kosse, N. M.; Brands, K.; Bauer, J. M.; Hortobagyi, T.; Lamoth, C. J. C.

    Background: Falls are a serious health problem in old adults especially in nursing home residents and hospitalized patients. To prevent elderly from falling, sensors have been increasingly used in intramural care settings. However, there is no clear overview of the current used technologies and

  4. A non-invasive thermal drift compensation technique applied to a spin-valve magnetoresistive current sensor.

    Science.gov (United States)

    Sánchez Moreno, Jaime; Ramírez Muñoz, Diego; Cardoso, Susana; Casans Berga, Silvia; Navarro Antón, Asunción Edith; Peixeiro de Freitas, Paulo Jorge

    2011-01-01

    A compensation method for the sensitivity drift of a magnetoresistive (MR) Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC). No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensation has been solved in the interval from 0 °C to 70 °C measuring currents from -10 A to +10 A.

  5. A Non-Invasive Thermal Drift Compensation Technique Applied to a Spin-Valve Magnetoresistive Current Sensor

    Directory of Open Access Journals (Sweden)

    Paulo Jorge Peixeiro de Freitas

    2011-02-01

    Full Text Available A compensation method for the sensitivity drift of a magnetoresistive (MR Wheatstone bridge current sensor is proposed. The technique was carried out by placing a ruthenium temperature sensor and the MR sensor to be compensated inside a generalized impedance converter circuit (GIC. No internal modification of the sensor bridge arms is required so that the circuit is capable of compensating practical industrial sensors. The method is based on the temperature modulation of the current supplied to the bridge, which improves previous solutions based on constant current compensation. Experimental results are shown using a microfabricated spin-valve MR current sensor. The temperature compensation has been solved in the interval from 0 °C to 70 °C measuring currents from −10 A to +10 A.

  6. Self-Oscillating Fluxgate Current Sensor with Pulse Width Modulated Feedback

    OpenAIRE

    Milan Ponjavić; Radivoje Đurić

    2010-01-01

    A self-oscillating fluxgate current sensor with pulse-width modulated feedback is discussed in the paper. The current feedback creates additional dissipation in the circuit which could be reduced by applying the method of pulse-width modulation. For simplicity, the pulse-width modulator is realized as a selfoscillating structure whosefrequency is adjusted by means of the hysteresis of a regenerative comparator, and the feedback is realized with no additional winding.

  7. A Method to Simultaneously Detect the Current Sensor Fault and Estimate the State of Energy for Batteries in Electric Vehicles.

    Science.gov (United States)

    Xu, Jun; Wang, Jing; Li, Shiying; Cao, Binggang

    2016-08-19

    Recently, State of energy (SOE) has become one of the most fundamental parameters for battery management systems in electric vehicles. However, current information is critical in SOE estimation and current sensor is usually utilized to obtain the latest current information. However, if the current sensor fails, the SOE estimation may be confronted with large error. Therefore, this paper attempts to make the following contributions: Current sensor fault detection and SOE estimation method is realized simultaneously. Through using the proportional integral observer (PIO) based method, the current sensor fault could be accurately estimated. By taking advantage of the accurate estimated current sensor fault, the influence caused by the current sensor fault can be eliminated and compensated. As a result, the results of the SOE estimation will be influenced little by the fault. In addition, the simulation and experimental workbench is established to verify the proposed method. The results indicate that the current sensor fault can be estimated accurately. Simultaneously, the SOE can also be estimated accurately and the estimation error is influenced little by the fault. The maximum SOE estimation error is less than 2%, even though the large current error caused by the current sensor fault still exists.

  8. Modeling Earth Albedo Currents on Sun Sensors for Improved Vector Observations

    DEFF Research Database (Denmark)

    Bhanderi, Dan

    2006-01-01

    Earth albedo influences vector measurements of the solar line of sight vector, due to the induced current on in the photo voltaics of Sun sensors. Although advanced digital Sun sensors exist, these are typically expensive and may not be suited for satellites in the nano or pico-class. Previously...... an Earth albedo model, based on reflectivity data from NASA's Total Ozone Mapping Spectrometer project, has been published. In this paper the proposed model is presented, and the model is sought validated by comparing simulated data with telemetry from the Danish Ørsted satellite. A novel method...

  9. A Multichannel Calorimetric Simultaneous Assay Platform Using a Microampere Constant-Current Looped Enthalpy Sensor Array

    Directory of Open Access Journals (Sweden)

    Hsien-Chin Wei

    2017-02-01

    Full Text Available Calorimetric biochemical measurements offer various advantages such as low waste, low cost, low sample consumption, short operating time, and labor-savings. Multichannel calorimeters can enhance the possibility of performing higher-throughput biochemical measurements. An enthalpy sensor (ES array is a key device in multichannel calorimeters. Most ES arrays use Wheatstone bridge amplifiers to condition the sensor signals, but such an approach is only suitable for null detection and low resistance sensors. To overcome these limitations, we have developed a multichannel calorimetric simultaneous assay (MCSA platform. An adjustable microampere constant-current (AMCC source was designed for exciting the ES array using a microampere current loop measurement circuit topology. The MCSA platform comprises a measurement unit, which contains a multichannel calorimeter and an automatic simultaneous injector, and a signal processing unit, which contains multiple ES signal conditioners and a data processor. This study focused on the construction of the MCSA platform; in particular, construction of the measurement circuit and calorimeter array in a single block. The performance of the platform, including current stability, temperature sensitivity and heat sensitivity, was evaluated. The sensor response time and calorimeter constants were given. The capability of the platform to detect relative enzyme activity was also demonstrated. The experimental results show that the proposed MCSA is a flexible and powerful biochemical measurement device with higher throughput than existing alternatives.

  10. The criterion for blanking-off heat-transfer tubes in the steam generators at VVER-based nuclear power plants based on the results of eddy-current examination

    Science.gov (United States)

    Lunin, V. P.; Zhdanov, A. G.; Chegodaev, V. V.; Stolyarov, A. A.

    2015-05-01

    The problem of defining the criterion for blanking off heat-transfer tubes in the steam generators at nuclear power plants on the basis of signals obtained from the standard multifrequency eddy-current examination is considered. The decision about blanking off one or another tube is presently made with reference to one parameter of the relevant signal at the working frequency, namely, with reference to its phase, which directly depends on the depth of the flaw being detected, i.e., a crack in the tube. The crack depth equal to 60% of the tube wall thickness is regarded to be the critical one, at which a decision about withdrawing such a tube out from operation (blanking off) must be taken. However, since mechanical tensile rupture tests of heat-transfer tubes show the possibility of their further use with such flaws, the secondary parameter of the signal, namely, its amplitude, must be used for determining the blanking-off criterion. The signals produced by the standard flow-type transducers in response to flaws in the form of a longitudinal crack having the depth and length within the limits permitted by the relevant regulations were calculated using 3D finite-element modeling. Based on the obtained results, the values of the eddy-current signal amplitude were determined, which, together with the signal phase value, form a new amplitude-phase criterion for blanking off heat-transfer tubes. For confirming the effectiveness of this technique, the algorithm for revealing the signal indications satisfying the proposed amplitude-phase criterion was tested on real signals obtained from operational eddy-current examination of the state of steam generator heat-transfer tubes carried out within the framework of planned preventive repair.

  11. Calibration of Hall sensor array for critical current measurement of YBCO tape with ferromagnetic substrate

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yunpeng; Wang, Gang; Liu, Liyuan [Key laboratory of Magnetic levitation Technologies and Maglev Trains (Ministry of Education), Superconductor and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, 610031 (China); Yang, Xinsheng, E-mail: xsyang@swjtu.edu.cn [Key laboratory of Magnetic levitation Technologies and Maglev Trains (Ministry of Education), Superconductor and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, 610031 (China); Zhao, Yong [Key laboratory of Magnetic levitation Technologies and Maglev Trains (Ministry of Education), Superconductor and New Energy R& D Center, Mail Stop 165#, Southwest Jiaotong University, Chengdu, 610031 (China); Superconductivity Research Group, School of Materials Science and Engineering, University of New South Wale, Sydney 2052, NSW (Australia)

    2015-12-15

    Abstract : HAS (Hall sensor array) is a powerful tool to detect the uniformity of HTS (high temperature superconductor) tape through mapping the distribution of remanent or shielding field along the surface of the tape. However, measurement of HTS tape with ferromagnetic parts by HSA is still an issue because the ferromagnetic substrate has influence on the magnetic field around the HTS layer. In this work, a continuous HSA system has been designed to measure the critical current of the YBCO tape with ferromagnetic substrate. The relationship between the remanent field and critical current was calibrated by the finite element method. The result showed that the HSA is an effective method for evaluating the critical current of the HTS tape with ferromagnetic substrate. - Highlight: • A continuous Hall sensor array system has been designed. • The inhomogeneity of YBCO tape with ferromagnetic substrate can be detected by HAS. • Finite element method is an effective method for calibrating the remanent field.

  12. Equatorward translation of the Vitoria Eddy in a numerical simulation

    Science.gov (United States)

    Campos, Edmo J. D.

    2006-11-01

    The Vitoria Eddy is a cyclonic vortex in the Brazil Current immediately to the South of the Vitoria-Trindade Ridge. Schmid et al. (1995) observed one such eddy that initially translated to the northeast, for about 17 days, and then moved back to the south. In this letter we report results of an eddy-resolving OGCM in which cyclonic eddies are formed in the same region. Although similar in structure to the observed feature, in our simulations the eddies present two different modes of translation. In one case, the eddy moves initially to the northeast, then remains stationary for a while, and finally moves back to the south. In the other, the eddy does not stop. It continues moving northward, crossing the Vitoria-Trindade chain and the Abrolhos Bank. In spite of not being impossible, to our knowledge this second behavior has never been reported.

  13. Projected changes to Tasman Sea eddies in a future climate

    Science.gov (United States)

    Oliver, Eric C. J.; O'Kane, Terence J.; Holbrook, Neil J.

    2015-11-01

    The Tasman Sea is a hot spot of ocean warming, that is linked to the increased poleward influence of the East Australian Current (EAC) over recent decades. Specifically, the EAC produces mesoscale eddies which have significant impacts on the physical, chemical, and biological properties of the Tasman Sea. To effectively consider and explain potential eddy changes in the next 50 years, we use high-resolution dynamically downscaled climate change simulations to characterize the projected future marine climate and mesoscale eddies in the Tasman Sea through the 2060s. We assess changes in the marine climate and the eddy field using bulk statistics and by detecting and tracking individual eddies. We find that the eddy kinetic energy is projected to increase along southeast Australia. In addition, we find that eddies in the projected future climate are composed of a higher proportion of anticyclonic eddies in this region and that these eddies are longer lived and more stable. This amounts to nearly a doubling of eddy-related southward temperature transport in the upper 200 m of the Tasman Sea. These changes are concurrent with increases in baroclinic and barotropic instabilities focused around the EAC separation point. This poleward transport and increase in eddy activity would be expected to also increase the frequency of sudden warming events, including ocean temperature extremes, with potential impacts on marine fisheries, aquaculture, and biodiversity off Tasmania's east coast, through direct warming or competition/predation from invasive migrating species.

  14. True eddy accumulation and eddy covariance methods and instruments intercomparison for fluxes of CO2, CH4 and H2O above the Hainich Forest

    Science.gov (United States)

    Siebicke, Lukas

    2017-04-01

    The eddy covariance (EC) method is state-of-the-art in directly measuring vegetation-atmosphere exchange of CO2 and H2O at ecosystem scale. However, the EC method is currently limited to a small number of atmospheric tracers by the lack of suitable fast-response analyzers or poor signal-to-noise ratios. High resource and power demands may further restrict the number of spatial sampling points. True eddy accumulation (TEA) is an alternative method for direct and continuous flux observations. Key advantages are the applicability to a wider range of air constituents such as greenhouse gases, isotopes, volatile organic compounds and aerosols using slow-response analyzers. In contrast to relaxed eddy accumulation (REA), true eddy accumulation (Desjardins, 1977) has the advantage of being a direct method which does not require proxies. True Eddy Accumulation has the potential to overcome above mentioned limitations of eddy covariance but has hardly ever been successfully demonstrated in practice in the past. This study presents flux measurements using an innovative approach to true eddy accumulation by directly, continuously and automatically measuring trace gas fluxes using a flow-through system. We merge high-frequency flux contributions from TEA with low-frequency covariances from the same sensors. We show flux measurements of CO2, CH4 and H2O by TEA and EC above an old-growth forest at the ICOS flux tower site "Hainich" (DE-Hai). We compare and evaluate the performance of the two direct turbulent flux measurement methods eddy covariance and true eddy accumulation using side-by-side trace gas flux observations. We further compare performance of seven instrument complexes, i.e. combinations of sonic anemometers and trace gas analyzers. We compare gas analyzers types of open-path, enclosed-path and closed-path design. We further differentiate data from two gas analysis technologies: infrared gas analysis (IRGA) and laser spectrometry (open path and CRDS closed

  15. Erosion of a California Undercurrent eddy by bottom topography

    Science.gov (United States)

    Torres, Hector S.; Gomez-Valdes, Jose

    2017-05-01

    Subsurface eddies are ubiquitous features in eastern boundary current systems. These phenomena tend to modulate the across-shore distribution of heat and biogeochemical tracers. A California Undercurrent eddy was detected by shipboard observations in October 2009 off the northern Baja California continental slope. The spatiotemporal variation in the California Undercurrent eddy is investigated by using a mesoscale-resolving hindcast ocean simulation. A poleward coastal current that is driven by an upwelling-wind relaxation event and the coastline geometry instigated the separation of the California Undercurrent from the slope, forming a meander-like structure, which evolved as a mesoscale eddy-like structure. The latter structure evolved as a subsurface eddy with a warm anomaly core, a distinctive feature of eddies that form from the California Undercurrent. During the initial stage, the subsurface eddy presented a cone-shape form, with the maximum amplitude of the relative vorticity in the upper section. The inviscid effect of the irregular bottom topography altered both the initial direction of propagation and the initial eddy shape: the propagation direction of the eddy changed from north-south to southwest, and the shape changed from a cone shape to a subsurface lens shape. The strong eddy-topography interactions triggered a sign change in the heat flux direction from the environment toward the eddy and vice versa through the horizontally divergent component of the velocity field, which accelerated the eddy's decay. This study shows the relevance of the synoptic wind stress events and the irregularity of the bottom topography on the mesoscale eddy activity in the southern portion of the California Current.

  16. Modeling of an eddy-current ferrite-cored probe response in time harmonic regime; Modelisation de la reponse d'un capteur a courants de Foucault comportant un noyau ferromagnetique en regime harmonique

    Energy Technology Data Exchange (ETDEWEB)

    Buvat, F

    2005-07-01

    In aeronautics, non destructive evaluation by eddy-current is commonly used to detect corrosion area or cracks in structures. Eddy-current testing by using ferrite-cored probes is effective to detect these kind of defects. So, having a model able to predict these probes responses is a major endeavor. Our work consisted in developing a model determining the ferrite-cored probes response to a defect. To model fields inside both the core and the defect, an integral formulation has been used resulting from the application of the Green theorem onto the equations of propagation. Simulation results have been compared to synthetic data obtained by a finite-element method and they have been validated by comparison with measured impedance data. However as this model may be computationally costly, the use of the so-called non-linear approximation has been tested to tackle the case of long defects. The model has been integrated inside the CIVA platform developed by the CEA. (author)

  17. Current Sensor Fault Diagnosis Based on a Sliding Mode Observer for PMSM Driven Systems.

    Science.gov (United States)

    Huang, Gang; Luo, Yi-Ping; Zhang, Chang-Fan; Huang, Yi-Shan; Zhao, Kai-Hui

    2015-05-11

    This paper proposes a current sensor fault detection method based on a sliding mode observer for the torque closed-loop control system of interior permanent magnet synchronous motors. First, a sliding mode observer based on the extended flux linkage is built to simplify the motor model, which effectively eliminates the phenomenon of salient poles and the dependence on the direct axis inductance parameter, and can also be used for real-time calculation of feedback torque. Then a sliding mode current observer is constructed in αβ coordinates to generate the fault residuals of the phase current sensors. The method can accurately identify abrupt gain faults and slow-variation offset faults in real time in faulty sensors, and the generated residuals of the designed fault detection system are not affected by the unknown input, the structure of the observer, and the theoretical derivation and the stability proof process are concise and simple. The RT-LAB real-time simulation is used to build a simulation model of the hardware in the loop. The simulation and experimental results demonstrate the feasibility and effectiveness of the proposed method.

  18. MOS-FET as a Current Sensor in Power Electronics Converters

    Directory of Open Access Journals (Sweden)

    Rok Pajer

    2015-07-01

    Full Text Available This paper presents a current sensing principle appropriate for use in power electronics’ converters. This current measurement principle has been developed for metal oxide semiconductor field effect transistor (MOS-FET and is based on UDS voltage measurement. In practice, shunt resistors and Hall effect sensors are usually used for these purposes, but the presented principle has many advantages. There is no need for additional circuit elements within high current paths, causing parasitic inductances and increased production complexity. The temperature dependence of MOS-FETs conductive resistance RDS−ON is considered in order to achieve the appropriate measurement accuracy. The “MOS-FET sensor” is also accompanied by a signal acquisition electronics circuit with an appropriate frequency bandwidth. The obtained analogue signal is therefore interposed to an A-D converter for further data acquisition. In order to achieve sufficient accuracy, a temperature compensation and appropriate approximation is used (RDS−ON = RDS−ON(Vj. The MOS-FET sensor is calibrated according to a reference sensor based on the Hall-effect principle. The program algorithm is executed on 32-bit ARM M4 MCU, STM32F407.

  19. A synergy study between microwave SST sensors and altimeters to retrieve surface geostrophic currents

    Science.gov (United States)

    Tandeo, Pierre; Saraceno, Martin; Fablet, Ronan; Ruiz, Juan

    The synergy between satellite measurements of Sea Surface Temperature (SST) and Sea Surface Height (SSH) has been studied in the last decades. Among the main approaches, we find methodologies based on (i) global analysis using empirical orthogonal functions (cf. Leuliette and Wahr 1999), (ii) local analysis using surface quasi-geostrophic dynamics (cf. Isern-Fontanet et al. 2006) or (iii) local patch-based regressions introducing a latent variable (cf. Tandeo et al. 2013). This last approach is able to identify and track (temporally and spatially) different relationships between local SST and SSH that correspond to different dynamical modes at the surface of the ocean, characterized by geostrophic/advective displacements with different amplitudes. In this work, Markovian priors are combined with remote sensing data including chlorophyll-a and sea surface salinity along with textit{in-situ} measurements of the mixed layer depth, to physically constrain the identification of the dynamical modes. Then, using this information of surface dynamics and daily microwave SST data, we make estimation of mesoscale geostrophic surface currents. We compare them to the reference Aviso product which only use altimetric data. The results show accurate identification of eddies and ocean fronts in the Brazil-Malvinas confluence region in the Southwestern Atlantic.

  20. Disjunct eddy covariance technique for trace gas flux measurements

    Science.gov (United States)

    Rinne, H. J. I.; Guenther, A. B.; Warneke, C.; de Gouw, J. A.; Luxembourg, S. L.

    A new approach for eddy covariance flux measurements is developed and applied for trace gas fluxes in the atmospheric surface layer. In disjunct eddy covariance technique, quick samples with a relatively long time interval between them are taken instead of continuously sampling air. This subset of the time series together with vertical wind velocity data at corresponding sampling times can be correlated to give a flux. The disjunct eddy sampling gives more time to analyze the trace gas concentrations and thus makes eddy covariance measurements possible using slower sensors. In this study a proton-transfer-reaction mass spectrometer with response time of about 1 second was used with a disjunct eddy sampler to measure fluxes of volatile organic compounds from an alfalfa field. The measured day-time maximum methanol fluxes ranged from 1 mg m-2 h-1 from uncut alfalfa to 8 mg m-2 h-1 from freshly cut alfalfa. Night-time fluxes were around zero.

  1. The MAIN Shirt: A Textile-Integrated Magnetic Induction Sensor Array

    OpenAIRE

    Teichmann, Daniel; Kuhn, Andreas; Leonhardt, Steffen; Walter, Marian

    2014-01-01

    A system is presented for long-term monitoring of respiration and pulse. It comprises four non-contact sensors based on magnetic eddy current induction that are textile-integrated into a shirt. The sensors are technically characterized by laboratory experiments that investigate the sensitivity and measuring depth, as well as the mutual interaction between adjacent pairs of sensors. The ability of the device to monitor respiration and pulse is demonstrated by measurements in healthy volunteers...

  2. Nonplanar fiber-optic sensing head for the compensation of bending-induced birefringence in Faraday current sensors.

    Science.gov (United States)

    Perciante, César D; Aparicio, Sofía; Illa, Ricardo; Ferrari, José A

    2015-06-20

    We demonstrate the compensation of bending-induced linear birefringence in single-mode fibers coiled in a nonplanar path by alternating orthogonal bending planes. This effect can be applied for the construction of birefringence-free fiber coils in Faraday sensor heads (e.g., in current sensors) to improve their sensitivity. Validation experiments are presented.

  3. Eddy properties in the Subtropical Countercurrent, Western Philippine Sea

    Science.gov (United States)

    Ramp, S. R.; Colosi, J. A.; Worcester, P. F.; Bahr, F. L.; Heaney, K. D.; Mercer, J. A.; Van Uffelen, L. J.

    2017-07-01

    An array of six oceanographic moorings with acoustic and environmental sensors was deployed in the central Philippine Sea from April 2010 to April 2011. The location spanned 18-23°N, 124 - 130°E in the Subtropical Countercurrent (STCC). The most prominent feature of the data set was a densely-packed eddy field with about equal numbers of cyclones and anticyclones moving westward at 6-12 km d-1. Eddies of either sign displaced the thermocline about ±50 m and had surface velocities exceeding 110 cm s-1. While warm eddies were slightly larger than cold eddies, the distance to maximum radial velocity was similar for both at about 65 km, close to the local Rossby radius of deformation. The steepness parameter U/c in the eddies ranged from 3 to 10, accompanied by relative vorticity of order 0.1-0.3 f, suggesting nonlinear, quasigeostrophic features with trapped cores rather than linear waves. This was borne out by the water mass analysis which showed high salinity, high spice North Pacific Tropical Water (NPTW) being transported westward in the warm eddy cores. The total KE and APE in eddies of both signs was about 1×1015 J with 85% of the APE and 74% of the KE located above 250 m depth. This equipartitioning of energy suggests mature eddies near equilibrium, that had been evolving for some time as they propagated into the area from the east.

  4. Modeling and Controller Design of PV Micro Inverter without Using Electrolytic Capacitors and Input Current Sensors

    Directory of Open Access Journals (Sweden)

    Faa Jeng Lin

    2016-11-01

    Full Text Available This paper outlines the modeling and controller design of a novel two-stage photovoltaic (PV micro inverter (MI that eliminates the need for an electrolytic capacitor (E-cap and input current sensor. The proposed MI uses an active-clamped current-fed push-pull DC-DC converter, cascaded with a full-bridge inverter. Three strategies are proposed to cope with the inherent limitations of a two-stage PV MI: (i high-speed DC bus voltage regulation using an integrator to deal with the 2nd harmonic voltage ripples found in single-phase systems; (ii inclusion of a small film capacitor in the DC bus to achieve ripple-free PV voltage; (iii improved incremental conductance (INC maximum power point tracking (MPPT without the need for current sensing by the PV module. Simulation and experimental results demonstrate the efficacy of the proposed system.

  5. A Novel Transient Fault Current Sensor Based on the PCB Rogowski Coil for Overhead Transmission Lines.

    Science.gov (United States)

    Liu, Yadong; Xie, Xiaolei; Hu, Yue; Qian, Yong; Sheng, Gehao; Jiang, Xiuchen

    2016-05-21

    The accurate detection of high-frequency transient fault currents in overhead transmission lines is the basis of malfunction detection and diagnosis. This paper proposes a novel differential winding printed circuit board (PCB) Rogowski coil for the detection of transient fault currents in overhead transmission lines. The interference mechanism of the sensor surrounding the overhead transmission line is analyzed and the guideline for the interference elimination is obtained, and then a differential winding printed circuit board (PCB) Rogowski coil is proposed, where the branch and return line of the PCB coil were designed to be strictly symmetrical by using a joining structure of two semi-rings and collinear twisted pair differential windings in each semi-ring. A serial test is conducted, including the frequency response, linearity, and anti-interference performance as well as a comparison with commercial sensors. Results show that a PCB Rogowski coil has good linearity and resistance to various external magnetic field interferences, thus enabling it to be widely applied in fault-current-collecting devices.

  6. Current infrared target acquisition approach for military sensor design and wargaming

    Science.gov (United States)

    Driggers, Ronald G.; Jacobs, Eddie L.; Vollmerhausen, Richard H.; O'Kane, Barbara; Self, Mid; Moyer, Steve; Hixson, Jonathan G.; Page, Gary; Krapels, Keith; Dixon, David; Kistner, Regina; Mazz, John

    2006-05-01

    The U.S. Army's infrared target acquisition models have been used for many years by the military sensor community, and there have been significant improvements to these models over the past few years. Significant improvements are the Target Task Performance (TTP) metric for all imaging sensors, the ACQUIRE-LC approach for low contrast infrared targets, and the development of discrimination criteria for the urban environment. This paper is intended to provide an overview of the current infrared target acquisition modeling approach. This paper will discuss recent advances and changes to the models and methodologies used to: (1) design and compare sensors, (2) predict expected target acquisition performance in the field, (3) predict target detection performance for combat simulations, (4) measure and characterize human operator performance in an operational environment (field performance), and (5) relate the models to target acquisition tasks and address targets that are relevant to urban operations. Finally, we present a catalog of discrimination criteria, characteristic dimensions, and target contrasts.

  7. Dark Current Random Telegraph Signals in Solid-State Image Sensors

    OpenAIRE

    Virmontois, Cédric; Goiffon, Vincent; Mark S Robbins; Tauziède, Laurie; Geoffray, Hervé; Raine, Mélanie; Girard, Sylvain; Gilard, Olivier; Magnan, Pierre; Bardoux, Alain

    2013-01-01

    This paper focuses on the Dark Current-Random Telegraph Signal (DC-RTS) in solid-state image sensors. The DCRTS is investigated in several bulk materials, for different surface interfaces and for different trench isolation interfaces. The main parameter used to characterize the DC-RTS is the transition maximum amplitude which seems to be the most appropriate for studying the phenomenon and identifying its origin. Proton, neutron and Co-60 Gamma-ray irradiations are used to study DC-RTS induce...

  8. Statistical Characteristics of Mesoscale Eddies in the North Pacific Derived from Satellite Altimetry

    Directory of Open Access Journals (Sweden)

    Yu-Hsin Cheng

    2014-06-01

    Full Text Available The sea level anomaly data derived from satellite altimetry are analyzed to investigate statistical characteristics of mesoscale eddies in the North Pacific. Eddies are detected by a free-threshold eddy identification algorithm. The results show that the distributions of size, amplitude, propagation speed, and eddy kinetic energy of eddy follow the Rayleigh distribution. The most active regions of eddies are the Kuroshio Extension region, the Subtropical Counter Current zone, and the Northeastern Tropical Pacific region. By contrast, eddies are seldom observed around the center of the eastern part of the North Pacific Subarctic Gyre. The propagation speed and kinetic energy of cyclonic and anticyclonic eddies are almost the same, but anticyclonic eddies possess greater lifespans, sizes, and amplitudes than those of cyclonic eddies. Most eddies in the North Pacific propagate westward except in the Oyashio region. Around the northeastern tropical Pacific and the California currents, cyclonic and anticyclonic eddies propagate westward with slightly equatorward (197° average azimuth relative to east and poleward (165° deflection, respectively. This implies that the background current may play an important role in formation of the eddy pathway patterns.

  9. Space Shuttle Program (SSP) Orbiter Main Propulsion System (MPS) Gaseous Hydrogen (GH2) Flow Control Valve (FCV) Poppet Eddy Current (EC) Inspection Probability of Detection (POD) Study. Volume 1

    Science.gov (United States)

    Piascik, Robert S.; Prosser, William H.

    2011-01-01

    The Director of the NASA Engineering and Safety Center (NESC), requested an independent assessment of the anomalous gaseous hydrogen (GH2) flow incident on the Space Shuttle Program (SSP) Orbiter Vehicle (OV)-105 during the Space Transportation System (STS)-126 mission. The main propulsion system (MPS) engine #2 GH2 flow control valve (FCV) LV-57 transition from low towards high flow position without being commanded. Post-flight examination revealed that the FCV LV-57 poppet had experienced a fatigue failure that liberated a section of the poppet flange. The NESC assessment provided a peer review of the computational fluid dynamics (CFD), stress analysis, and impact testing. A probability of detection (POD) study was requested by the SSP Orbiter Project for the eddy current (EC) nondestructive evaluation (NDE) techniques that were developed to inspect the flight FCV poppets. This report contains the findings and recommendations from the NESC assessment.

  10. Space Shuttle Program (SSP) Orbiter Main Propulsion System (MPS) Gaseous Hydrogen (GH2) Flow Control Valve (FCV) Poppet Eddy Current (EC) Inspection Probability of Detection (POD) Study. Volume 2; Appendices

    Science.gov (United States)

    Piascik, Robert S.; Prosser, William H.

    2011-01-01

    The Director of the NASA Engineering and Safety Center (NESC), requested an independent assessment of the anomalous gaseous hydrogen (GH2) flow incident on the Space Shuttle Program (SSP) Orbiter Vehicle (OV)-105 during the Space Transportation System (STS)-126 mission. The main propulsion system (MPS) engine #2 GH2 flow control valve (FCV) LV-57 transition from low towards high flow position without being commanded. Post-flight examination revealed that the FCV LV-57 poppet had experienced a fatigue failure that liberated a section of the poppet flange. The NESC assessment provided a peer review of the computational fluid dynamics (CFD), stress analysis, and impact testing. A probability of detection (POD) study was requested by the SSP Orbiter Project for the eddy current (EC) nondestructive evaluation (NDE) techniques that were developed to inspect the flight FCV poppets. This report contains the Appendices to the main report.

  11. Deep Eddies in the Gulf of Mexico

    Science.gov (United States)

    Furey, H. H.; Bower, A. S.; Perez-Brunius, P.; Hamilton, P.

    2014-12-01

    A major Lagrangian program is currently underway to map the deep (1500-2500 m) circulation of the entire Gulf of Mexico. Beginning in 2011, more than 120 acoustically tracked RAFOS floats have been released in the eastern, central and western Gulf, many in pairs and triplets. Most floats are programmed to drift for two years, obtaining position fixes and temperature/pressure measurements three times daily. More than 80 floats have completed their missions, and results from the trajectories will be described with a focus on mesoscale eddying behavior. In particular, the first-ever observations of deep energetic anticyclonic eddies (possibly lenses) forming at and separating from a northeastward-flowing boundary current west of Campeche Bank will be discussed. The existence of these eddies has major implications for exchange between the continental slope and interior Gulf. The project is being supported by the U.S. Bureau of Ocean Energy Management (BOEM).

  12. Sensors

    Energy Technology Data Exchange (ETDEWEB)

    Jensen, H. [PBI-Dansensor A/S (Denmark); Toft Soerensen, O. [Risoe National Lab., Materials Research Dept. (Denmark)

    1999-10-01

    A new type of ceramic oxygen sensors based on semiconducting oxides was developed in this project. The advantage of these sensors compared to standard ZrO{sub 2} sensors is that they do not require a reference gas and that they can be produced in small sizes. The sensor design and the techniques developed for production of these sensors are judged suitable by the participating industry for a niche production of a new generation of oxygen sensors. Materials research on new oxygen ion conducting conductors both for applications in oxygen sensors and in fuel was also performed in this project and finally a new process was developed for fabrication of ceramic tubes by dip-coating. (EHS)

  13. Sensors

    CERN Document Server

    Pigorsch, Enrico

    1997-01-01

    This is the 5th edition of the Metra Martech Directory "EUROPEAN CENTRES OF EXPERTISE - SENSORS." The entries represent a survey of European sensors development. The new edition contains 425 detailed profiles of companies and research institutions in 22 countries. This is reflected in the diversity of sensors development programmes described, from sensors for physical parameters to biosensors and intelligent sensor systems. We do not claim that all European organisations developing sensors are included, but this is a good cross section from an invited list of participants. If you see gaps or omissions, or would like your organisation to be included, please send details. The data base invites the formation of effective joint ventures by identifying and providing access to specific areas in which organisations offer collaboration. This issue is recognised to be of great importance and most entrants include details of collaboration offered and sought. We hope the directory on Sensors will help you to find the ri...

  14. Analysis and elimination of bias error in a fiber-optic current sensor.

    Science.gov (United States)

    Wang, Xiaxiao; Zhao, Zijie; Li, Chuansheng; Yu, Jia; Wang, Zhenjie

    2017-11-10

    Bias error, along with scale factor, is a key factor that affects the measurement accuracy of the fiber-optic current sensor. Because of polarization crosstalk, the coherence of parasitic interference signals could be rebuilt and form an output independent of the current to be measured, i.e., the bias error. The bias error is a variable of the birefringence optical path difference. Hence, when the temperature changes, the bias error shows a quasi-periodical tendency whose envelope curve reflects the coherence function of light source. By identifying the key factors of bias error and setting the propagation directions of a super-luminescent diode, polarization-maintaining coupler and polarizer to fast axis, it is possible to eliminate the coherence of parasitic interference signals. Experiments show that the maximum bias error decreases by one order of magnitude at temperatures between -40°C to 60°C.

  15. Inherent temperature compensation of fiber-optic current sensors employing spun highly birefringent fiber.

    Science.gov (United States)

    Müller, G M; Gu, X; Yang, L; Frank, A; Bohnert, K

    2016-05-16

    We investigate the various contributions to the temperature dependence of an interferometric fiber-optic current sensor employing spun highly-birefringent sensing fiber, in particular, the contributions from the fiber retarder at the fiber coil entrance, the spun fiber's birefringence, and the Faraday effect. We theoretically and experimentally demonstrate that an appropriately designed retarder inherently compensates the temperature dependence of the fiber birefringence and the Faraday effect. We demonstrate insensitivity to temperature to within ± 0.2% between -40 and + 85 °C. Furthermore, we analyze the influence of the retarder parameters on the linearity of the recovered magneto-optic phase shift vs. current and determine a set of parameters that results in a perfectly linear relationship.

  16. Modeling Mesoscale Eddies in the North Atlantic Ocean

    Science.gov (United States)

    Chao, Yi

    1999-01-01

    Ocean modeling plays an important role in understanding the current climatic conditions and predicting the future climate change. Modeling the ocean at eddy-permitting and/or eddy resolving resolutions (1/3 degree or higher) has a two-fold objective. One part is to represent the ocean as realistically as possible, because mesoscale eddies have an impact on the large-scale circulation. The second objective is to learn how to represent effects of mesoscale eddies without explicitly resolving them. This is particularly important for climate models which cannot be run at eddy-resolving resolutions because of the computational constraints. At JPL, a 1/6 degree latitude by 1/6 degree longitude with 37 vertical levels Atlantic Ocean model has been developed. The model is based on the Parallel Ocean Program (POP) developed at Los Alamos National Laboratory (LANL). Using the 256-processor Cray T3D, we have conducted a 40-year integration of this Atlantic eddy-resolving ocean model. A regional analysis demonstrate that many observed features associated with the Caribbean Sea eddies can be realistically simulated by this model. Analysis of this Atlantic eddy-resolving ocean model further suggests that these Caribbean Sea eddies are connected with eddies formed outside the Caribbean Sea at the confluence of the North Brazil Current (NBC) and the North Equatorial Countercurrent. The diagram of the model simulated surface current shows that the Caribbean eddies ultimately originate in the NBC retroflection region, traveling more than a year from the North Brazil coast through the Lesser Antilles into the Caribbean Sea and eventually into the Gulf of Mexico. Additional information is contained in the original.

  17. Modelling tide-driven currents and residual eddies in the Gulf of Kachchh and their seasonal variability: A marine environmental planning perspective

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, M.T.; Vethamony, P.; Desa, E.

    showed very good agreement with the measured currents. The study suggests that though the currents of GoK are predominantly tide-driven, they respond significantly to the seasonally changing wind system. Strong southwesterly winds enhance the flood tidal...

  18. Methane fluxes above the Hainich forest by True Eddy Accumulation and Eddy Covariance

    Science.gov (United States)

    Siebicke, Lukas; Gentsch, Lydia; Knohl, Alexander

    2016-04-01

    Understanding the role of forests for the global methane cycle requires quantifying vegetation-atmosphere exchange of methane, however observations of turbulent methane fluxes remain scarce. Here we measured turbulent fluxes of methane (CH4) above a beech-dominated old-growth forest in the Hainich National Park, Germany, and validated three different measurement approaches: True Eddy Accumulation (TEA, closed-path laser spectroscopy), and eddy covariance (EC, open-path and closed-path laser spectroscopy, respectively). The Hainich flux tower is a long-term Fluxnet and ICOS site with turbulent fluxes and ecosystem observations spanning more than 15 years. The current study is likely the first application of True Eddy Accumulation (TEA) for the measurement of turbulent exchange of methane and one of the very few studies comparing open-path and closed-path eddy covariance (EC) setups side-by-side. We observed uptake of methane by the forest during the day (a methane sink with a maximum rate of 0.03 μmol m-2 s-1 at noon) and no or small fluxes of methane from the forest to the atmosphere at night (a methane source of typically less than 0.01 μmol m-2 s-1) based on continuous True Eddy Accumulation measurements in September 2015. First results comparing TEA to EC CO2 fluxes suggest that True Eddy Accumulation is a valid option for turbulent flux quantifications using slow response gas analysers (here CRDS laser spectroscopy, other potential techniques include mass spectroscopy). The TEA system was one order of magnitude more energy efficient compared to closed-path eddy covariance. The open-path eddy covariance setup required the least amount of user interaction but is often constrained by low signal-to-noise ratios obtained when measuring methane fluxes over forests. Closed-path eddy covariance showed good signal-to-noise ratios in the lab, however in the field it required significant amounts of user intervention in addition to a high power consumption. We conclude

  19. Modelling of the North Atlantic eddy characteristics

    Science.gov (United States)

    Ushakov, Konstantin; Ibrayev, Rashit

    2017-04-01

    We investigate eddy characteristics of the Atlantic basin circulation and their impact on the ocean heat transport. A 15-year-long numerical experiment is performed with the global 3-dimensional z-coordinate INMIO ocean general circulation model of 0.1 deg., 49 levels resolution in conditions of the CORE-II protocol. The model is tuned to maximal intensity of eddies production by using only biharmonic filters instead of lateral viscous and diffusive terms in the model equations. Comparison with viscous and coarse-resolution simulations shows the increase of explicitly resolved heat transfer fraction and absolute values. Vertical turbulent mixing is parameterized by the Munk-Anderson scheme including convective adjustment. The sea ice is described by a simple thermodynamic submodel. The eddying velocity and temperature field components are defined as anomalies relative to the 3-month sliding mean. The regional distributions of hydrological parameters, eddy kinetic energy, heat convergence, meridional heat transport (MHT) and Atlantic meridional overturning circulation (AMOC) streamfunction, and their temporal variability are analyzed. In some parts of the basin the simulated eddy heat transport is opposite to the mean flow transport and may change direction with depth. The MHT intensity is slightly below observationally based assessments with notable influence of the East Greenland current simulation bias. The work is supported by the Russian Science Foundation (project N 14-27-00126) and performed in the Institute of Numerical Mathematics, Russian Academy of Sciences.

  20. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications

    Directory of Open Access Journals (Sweden)

    Julien Perchoux

    2016-05-01

    Full Text Available Optical feedback interferometry (OFI sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications.

  1. Current Developments on Optical Feedback Interferometry as an All-Optical Sensor for Biomedical Applications

    Science.gov (United States)

    Perchoux, Julien; Quotb, Adam; Atashkhooei, Reza; Azcona, Francisco J.; Ramírez-Miquet, Evelio E.; Bernal, Olivier; Jha, Ajit; Luna-Arriaga, Antonio; Yanez, Carlos; Caum, Jesus; Bosch, Thierry; Royo, Santiago

    2016-01-01

    Optical feedback interferometry (OFI) sensors are experiencing a consistent increase in their applications to biosensing due to their contactless nature, low cost and compactness, features that fit very well with current biophotonics research and market trends. The present paper is a review of the work in progress at UPC-CD6 and LAAS-CNRS related to the application of OFI to different aspects of biosensing, both in vivo and ex vivo. This work is intended to present the variety of opportunities and potential applications related to OFI that are available in the field. The activities presented are divided into two main sensing strategies: The measurement of optical path changes and the monitoring of flows, which correspond to sensing strategies linked to the reconstruction of changes of amplitude from the interferometric signal, and to classical Doppler frequency measurements, respectively. For optical path change measurements, measurements of transient pulses, usual in biosensing, together with the measurement of large displacements applied to designing palliative care instrumentation for Parkinson disease are discussed. Regarding the Doppler-based approach, progress in flow-related signal processing and applications in real-time monitoring of non-steady flows, human blood flow monitoring and OFI pressure myograph sensing will be presented. In all cases, experimental setups are discussed and results presented, showing the versatility of the technique. The described applications show the wide capabilities in biosensing of the OFI sensor, showing it as an enabler of low-cost, all-optical, high accuracy biomedical applications. PMID:27187406

  2. Sliding Mode Observer-Based Current Sensor Fault Reconstruction and Unknown Load Disturbance Estimation for PMSM Driven System.

    Science.gov (United States)

    Zhao, Kaihui; Li, Peng; Zhang, Changfan; Li, Xiangfei; He, Jing; Lin, Yuliang

    2017-12-06

    This paper proposes a new scheme of reconstructing current sensor faults and estimating unknown load disturbance for a permanent magnet synchronous motor (PMSM)-driven system. First, the original PMSM system is transformed into two subsystems; the first subsystem has unknown system load disturbances, which are unrelated to sensor faults, and the second subsystem has sensor faults, but is free from unknown load disturbances. Introducing a new state variable, the augmented subsystem that has sensor faults can be transformed into having actuator faults. Second, two sliding mode observers (SMOs) are designed: the unknown load disturbance is estimated by the first SMO in the subsystem, which has unknown load disturbance, and the sensor faults can be reconstructed using the second SMO in the augmented subsystem, which has sensor faults. The gains of the proposed SMOs and their stability analysis are developed via the solution of linear matrix inequality (LMI). Finally, the effectiveness of the proposed scheme was verified by simulations and experiments. The results demonstrate that the proposed scheme can reconstruct current sensor faults and estimate unknown load disturbance for the PMSM-driven system.

  3. Sliding Mode Observer-Based Current Sensor Fault Reconstruction and Unknown Load Disturbance Estimation for PMSM Driven System

    Directory of Open Access Journals (Sweden)

    Kaihui Zhao

    2017-12-01

    Full Text Available This paper proposes a new scheme of reconstructing current sensor faults and estimating unknown load disturbance for a permanent magnet synchronous motor (PMSM-driven system. First, the original PMSM system is transformed into two subsystems; the first subsystem has unknown system load disturbances, which are unrelated to sensor faults, and the second subsystem has sensor faults, but is free from unknown load disturbances. Introducing a new state variable, the augmented subsystem that has sensor faults can be transformed into having actuator faults. Second, two sliding mode observers (SMOs are designed: the unknown load disturbance is estimated by the first SMO in the subsystem, which has unknown load disturbance, and the sensor faults can be reconstructed using the second SMO in the augmented subsystem, which has sensor faults. The gains of the proposed SMOs and their stability analysis are developed via the solution of linear matrix inequality (LMI. Finally, the effectiveness of the proposed scheme was verified by simulations and experiments. The results demonstrate that the proposed scheme can reconstruct current sensor faults and estimate unknown load disturbance for the PMSM-driven system.

  4. Don Eddy; "Jewelry."

    Science.gov (United States)

    Schaefer, Claire

    1989-01-01

    Presents a lesson that introduces students in grades K-three to sources of design inspiration in contemporary urban settings. Using Don Eddy's painting of a jewelry store window display, asks students to describe and analyze the interplay of shape, pattern, and color. Suggests studio activities, including an activity in which students build a…

  5. Modeling And Simulation Of Electrical Prevenion System Using Arduino Uno,Gsm Modem, And Acs712 Current Sensor

    Science.gov (United States)

    Khair, Ummul; Jabbar Lubis, Abdul; Agustha, Indra; Dharmawati; Zulfin, M.

    2017-12-01

    The current electricity needs is very primary, all objects including electronics require power, it encourages people not to be able to save electricity so the theft of electric power would be done. The use of ACS712 current sensor as the sensor with arduino uno would find out the power consumption continuously and prevent the theft of electricity because of the use of electricity which has been determined by PLN and the people fetl that it is not enough for every house, so the author made a tool for prevention of theft of electric power by using the arduino uno, buzzer, ACS712 current sensor, lcd, and relay then the power usage can be controlled according to the use to prevent the occurrence of theft of electricity so the use can be seen directly on the lcd 16x2and GSM modem to give information to employees of PLN so that it can reduceelectrical theft by the public.

  6. Sokolua-Mvika, Eddy

    African Journals Online (AJOL)

    Sokolua-Mvika, Eddy. Vol 23, No 1 (2016) - Articles Carence en fer, anémie et anémie ferriprive chez les donneurs de sang à Kinshasa, République Démocratique du Congo Abstract PDF. ISSN: 1937-8688. AJOL African Journals Online. HOW TO USE AJOL... for Researchers · for Librarians · for Authors · FAQ's · More ...

  7. A True Eddy Accumulation - Eddy Covariance hybrid for measurements of turbulent trace gas fluxes

    Science.gov (United States)

    Siebicke, Lukas

    2016-04-01

    Eddy covariance (EC) is state-of-the-art in directly and continuously measuring turbulent fluxes of carbon dioxide and water vapor. However, low signal-to-noise ratios, high flow rates and missing or complex gas analyzers limit it's application to few scalars. True eddy accumulation, based on conditional sampling ideas by Desjardins in 1972, requires no fast response analyzers and is therefore potentially applicable to a wider range of scalars. Recently we showed possibly the first successful implementation of True Eddy Accumulation (TEA) measuring net ecosystem exchange of carbon dioxide of a grassland. However, most accumulation systems share the complexity of having to store discrete air samples in physical containers representing entire flux averaging intervals. The current study investigates merging principles of eddy accumulation and eddy covariance, which we here refer to as "true eddy accumulation in transient mode" (TEA-TM). This direct flux method TEA-TM combines true eddy accumulation with continuous sampling. The TEA-TM setup is simpler than discrete accumulation methods while avoiding the need for fast response gas analyzers and high flow rates required for EC. We implemented the proposed TEA-TM method and measured fluxes of carbon dioxide (CO2), methane (CH4) and water vapor (H2O) above a mixed beech forest at the Hainich Fluxnet and ICOS site, Germany, using a G2301 laser spectrometer (Picarro Inc., USA). We further simulated a TEA-TM sampling system using measured high frequency CO2 time series from an open-path gas analyzer. We operated TEA-TM side-by-side with open-, enclosed- and closed-path EC flux systems for CO2, H2O and CH4 (LI-7500, LI-7200, LI-6262, LI-7700, Licor, USA, and FGGA LGR, USA). First results show that TEA-TM CO2 fluxes were similar to EC fluxes. Remaining differences were similar to those between the three eddy covariance setups (open-, enclosed- and closed-path gas analyzers). Measured TEA-TM CO2 fluxes from our physical

  8. Eddy Powell 1939 - 2003

    CERN Multimedia

    2003-01-01

    We were saddened to learn that Eddy Powell had passed away on Saturday 26 July after a long illness. Eddy had so many friends at CERN and made such a contribution to the Organisation that it is impossible that his passing goes without comment. Eddy was born in England on 4 August 1939 and, after serving his apprenticeship with the U.K. Ministry of Defence, he joined CERN in September 1965. As an electrical design draftsman with the Synchro-cyclotron Division he played an important role in the upgrades of that machine in the early 1970's, particularly on the RF systems and later on the development of the ISOLDE facility. This brought him into close contact with many of the technical support services in CERN and, unlike many of his compatriots, he acquired a remarkably good fluency in French. Always inquisitive on the physics carried out at CERN, he spent a great deal of time learning from physicists and engineers at all levels. When he felt sufficiently confident he became a CERN Guide for general public visit...

  9. Integrity assessment of research reactor fuel cladding and material testing using eddy current inspection; Avaliacao de integridade de revestimentos de combustiveis de reatores de pesquisa e teste de materiais utilizando o ensaio de correntes parasitas

    Energy Technology Data Exchange (ETDEWEB)

    Alencar, Donizete Anderson de

    2004-07-01

    A methodology to perform the integrity assessment of research reactors nuclear fuels cladding, such as those installed in IPR-Rl (TRIGA) and IEA-R1 (MTR), using nondestructive electromagnetic inspection (eddy current) is presented. This methodology is constituted by: the development of calibration reference standards, specific for each type of fuel; the development of special test probes; the recommendations for the inspection equipment calibration; the construction of voltage based evaluation curves and the inspection procedures developed for the characterization of detected flaws. The test probes development, specially those designed for the inspection of MTR fuels cladding, which present access difficulties due to the narrow gap between fuel plates (2,89 mm for IEAR-R1), constituted a challenge that demanded the introduction of unusual materials and constructive techniques. The operational performance of the developed resources, as well as the special operative characteristics of the test probes, such as their immunity to adjacent fuel plates interference and electrical resistivity changes of the fuels meat are experimentally demonstrated. The practical applicability of the developed methodology is verified in non radioactive environment, using a dummy MTR fuel element model, similar to an IEA-R1 reactor fuel element, produced and installed in IPEN, Sao Paulo. The efficacy of the proposed methodology was verified by the achieved results. (author)

  10. Development and validation of a simulation tool dedicated to eddy current non destructive testing of tubes; Developpement d'un modele electromagnetique 3D pour la simulation du controle par Courants de Foucault de tubes en fabrication

    Energy Technology Data Exchange (ETDEWEB)

    Reboud, Ch

    2006-09-15

    Eddy current testing (ECT) technique is widely used in industrial fields such as iron and steel industry. Dedicated simulation tools provide a great assistance for the optimisation of ECT processes. CEA and the Vallourec Research Center have collaborated in order to develop a simulation tool of ECT of tubes. The volume integral method has been chosen for the resolution of Maxwell equations in a stratified medium, in order to get accurate results with a computation time short enough to carry out optimisation or inversion procedures. A fast model has been developed for the simulation of ECT of non magnetic tubes using specific external probes. New flaw geometries have been modelled: holes and notches with flat bottom. Validations of the developments, which have been integrated to the CIVA platform, have been carried out using experimental data recorded in laboratory conditions and in. industrial conditions, successively. The integral equations derived are solved using the Galerkin variant of the method of moments with pulse functions as projection functions. In order to overcome some memory limitations, other projection functions have been considered. A new discretization scheme based on non-uniform B-Splines of degree 1 or 2 has been implemented, which constitutes an original contribution to the existing literature. The decrease of the mesh size needed to get a given accuracy on the result may lead to the simulation of more complex ECT configurations. (author)

  11. Development of a 3-D model for eddy current testing: application for fastened structures in aeronautics; Developpement d'un modele pour le controle non destructif par courants de Foucault de structures rivetees en aeronautique

    Energy Technology Data Exchange (ETDEWEB)

    Paillard, S

    2007-12-15

    One of the Eddy Current Testing issues in aeronautics is the inspection of fastened structures to detect flaws nearby rivets which can grow because of mechanical stress. EADS and the CEA LIST have started a collaborative work with the support of the Ile-de-France Region to develop a simulation tool of EC fastened structures testing, integrated to the CIVA platform, aimed at conceiving testing methods, optimizing and qualifying it. The volume integral method using the Green dyadics formalism has been chosen in order to get a fast resolution of Maxwell equations. A first milestone was to build a simulation model of multilayer structures testing, thanks to the use of the multilayer Green dyads. Because of the rivet volume, 60 times bigger than the one of a typical flaw, a large number of discretization cells are needed. Therefore an iterative method has been developed in order to numerically solve large calculation zones. Finally, the flaw response simulation mostly has to cope with a scale issue between the size of the rivet and the one of the flaw, the latter being much smaller in a direction than the former. The whole model has been experimentally validated and compared to other simulation models at the important development steps: multilayer configuration, iteration resolution, and flaw signature. (author)

  12. Small Signals’ Study of Thermal Induced Current in Nanoscale SOI Sensor

    Directory of Open Access Journals (Sweden)

    Yaakov Mandelbaum

    2017-01-01

    Full Text Available A new nanoscale SOI dual-mode modulator is investigated as a function of optical and thermal activation modes. In order to accurately characterize the device specifications towards its future integration in microelectronics circuitry, current time variations are studied and compared for “large signal” constant temperature changes, as well as for “small signal” fluctuating temperature sources. An equivalent circuit model is presented to define the parameters which are assessed by numerical simulation. Assuring that the thermal response is fast enough, the device can be operated as a modulator via thermal stimulation or, on the other hand, can be used as thermal sensor/imager. We present here the design, simulation, and model of the next generation which seems capable of speeding up the processing capabilities. This novel device can serve as a building block towards the development of optical/thermal data processing while breaking through the way to all optic processors based on silicon chips that are fabricated via typical microelectronics fabrication process.

  13. Development of a High-Speed Current Injection and Voltage Measurement System for Electrical Impedance Tomography-Based Stretchable Sensors

    Directory of Open Access Journals (Sweden)

    Stefania Russo

    2017-07-01

    Full Text Available Electrical impedance tomography (EIT is an imaging method that can be applied over stretchable conductive-fabric materials to realize soft and wearable pressure sensors through current injections and voltage measurements at electrodes placed at the boundary of a conductive medium. In common EIT systems, the voltage data are serially measured by means of multiplexers, and are hence collected at slightly different times, which affects the real-time performance of the system. They also tend to have complicated hardware, which increases power consumption. In this paper, we present our design of a 16-electrode high-speed EIT system that simultaneously implements constant current injection and differential potential measurements. This leads to a faster, simpler-to-implement and less-noisy technique, when compared with traditional EIT approaches. Our system consists of a Howland current pump with two multiplexers for a constant DC current supply, and a data acquisition card. It guarantees a data collection rate of 78 frames/s. The results from our conductive stretchable fabric sensor show that the system successfully performs voltage data collection with a mean signal-to-noise ratio (SNR of 55 dB, and a mean absolute deviation (MAD of 0.5 mV. The power consumption can be brought down to 3 mW; therefore, it is suitable for battery-powered applications. Finally, pressure contacts over the sensor are properly reconstructed, thereby validating the efficiency of our EIT system for soft and stretchable sensor applications.

  14. EDDIE RICKENBACKER: RACETRACK ENTREPRENEUR

    Directory of Open Access Journals (Sweden)

    W. David Lewis

    2000-01-01

    Full Text Available Edward V. (Eddie Rickenbacker (1890-1973 is best remembered for hisrecord as a combat pilot in World War I, in which he shot down 26 Germa naircraft and won fame as America’s "Ace of Aces." From 1934 until 1963 he was general manager, president, and board chairman of Eastern Air Lines, which was for a time the most profitable air carrier in the United States. This paper shows how Rickenbacker’s fiercely entrepreneurial style of management was born in his early involvement in the automobile industry, and particularly in his career as an automobile racing driver from 1909 through 1916.

  15. Stand alone, low current measurements on possible sensing platforms via Arduino Uno microcontroller with modified commercially available sensors

    Science.gov (United States)

    Tanner, Meghan; Henson, Gabriel; Senevirathne, Indrajith

    Advent of cost-effective solid-state sensors has spurred an immense interest in microcontrollers, in particular Arduino microcontrollers. These include serious engineering and physical science applications due to their versatility and robustness. An Arduino microcontroller coupled with a commercially available sensor has been used to methodically measure, record, and explore low currents, low voltages, and corresponding dissipated power towards assessing secondary physical properties in a select set of engineered systems. System was assembled via breadboard, wire, and simple soldering with an Arduino Uno with ATmega328P microcontroller connected to a PC. The microcontroller was programmed with Arduino software while the bootloader was used to upload the code. High-side measurement INA169 current shunt monitor was used to measure corresponding low to ultra-low currents and voltages. A collection of measurements was obtained via the sensor and was compared with measurements from standardized devices to assess reliability and uncertainty. Some sensors were modified/hacked to improve the sensitivity of the measurements.

  16. Wireless Distributed Environmental Sensor Networks for Air Pollution Measurement—The Promise and the Current Reality

    Science.gov (United States)

    2017-01-01

    The evaluation of the effects of air pollution on public health and human-wellbeing requires reliable data. Standard air quality monitoring stations provide accurate measurements of airborne pollutant levels, but, due to their sparse distribution, they cannot capture accurately the spatial variability of air pollutant concentrations within cities. Dedicated in-depth field campaigns have dense spatial coverage of the measurements but are held for relatively short time periods. Hence, their representativeness is limited. Moreover, the oftentimes integrated measurements represent time-averaged records. Recent advances in communication and sensor technologies enable the deployment of dense grids of Wireless Distributed Environmental Sensor Networks for air quality monitoring, yet their capability to capture urban-scale spatiotemporal pollutant patterns has not been thoroughly examined to date. Here, we summarize our studies on the practicalities of using data streams from sensor nodes for air quality measurement and the required methods to tune the results to different stakeholders and applications. We summarize the results from eight cities across Europe, five sensor technologies-three stationary (with one tested also while moving) and two personal sensor platforms, and eight ambient pollutants. Overall, few sensors showed an exceptional and consistent performance, which can shed light on the fine spatiotemporal urban variability of pollutant concentrations. Stationary sensor nodes were more reliable than personal nodes. In general, the sensor measurements tend to suffer from the interference of various environmental factors and require frequent calibrations. This calls for the development of suitable field calibration procedures, and several such in situ field calibrations are presented. PMID:28974042

  17. Wireless Distributed Environmental Sensor Networks for Air Pollution Measurement-The Promise and the Current Reality.

    Science.gov (United States)

    Broday, David M

    2017-10-02

    The evaluation of the effects of air pollution on public health and human-wellbeing requires reliable data. Standard air quality monitoring stations provide accurate measurements of airborne pollutant levels, but, due to their sparse distribution, they cannot capture accurately the spatial variability of air pollutant concentrations within cities. Dedicated in-depth field campaigns have dense spatial coverage of the measurements but are held for relatively short time periods. Hence, their representativeness is limited. Moreover, the oftentimes integrated measurements represent time-averaged records. Recent advances in communication and sensor technologies enable the deployment of dense grids of Wireless Distributed Environmental Sensor Networks for air quality monitoring, yet their capability to capture urban-scale spatiotemporal pollutant patterns has not been thoroughly examined to date. Here, we summarize our studies on the practicalities of using data streams from sensor nodes for air quality measurement and the required methods to tune the results to different stakeholders and applications. We summarize the results from eight cities across Europe, five sensor technologies-three stationary (with one tested also while moving) and two personal sensor platforms, and eight ambient pollutants. Overall, few sensors showed an exceptional and consistent performance, which can shed light on the fine spatiotemporal urban variability of pollutant concentrations. Stationary sensor nodes were more reliable than personal nodes. In general, the sensor measurements tend to suffer from the interference of various environmental factors and require frequent calibrations. This calls for the development of suitable field calibration procedures, and several such in situ field calibrations are presented.

  18. Self-organizing cooperative sensor network for remote surveillance: current results

    Science.gov (United States)

    Burne, Richard A.; Buczak, Anna L.; Jin, Yaochu; Jamalabad, Vikram R.; Kadar, Ivan; Eadan, Eitan R.

    1999-07-01

    The capabilities of unattended ground sensors (UGSs) have steadily improved and have been shown to be of value in various military missions. Today's UGS are multi-functional, integrated sensor platforms that can detect and locate a wide variety of ground-based and airborne targets. The rather large size (> 1 cubic foot) and relatively expensive cost of these integrated platforms are two main drawbacks for remote surveillance applications that support rapidly deployable, small unit operations. As an alternative, remote surveillance may be possible with smaller, less costly sensors that work cooperatively together as a network. The objective of this study was to develop algorithms that can optimally organized and adaptively control a network of UGSs in order to achieve a surveillance mission. In the present study, the sensor network, a random distribution of acoustic sensors over a surveillance area, is tasked to detect and track any targets entering into the surveillance area. In addition, the sensor network is required to maximize its tracking accuracy and minimize its power utilization.

  19. Optimizing an integrated waveguide modulator for sensitive low-frequency alternating-current electric-field sensors

    Science.gov (United States)

    Al-Tarawni, Musab A. M.; Bakar, A. Ashrif A.; Zain, Ahmad Rifqi Md; Tarawneh, Mou'ad A.; Ahmad, Sahrim Hj.

    2017-06-01

    The use of integrated waveguide modulators is a common technique in electric-field sensing. However, the distortion in the modulated signal caused by high half-voltage Vπ and the difficulty in obtaining low-frequency responses are challenging issues for the use of low-frequency alternating-current (AC) electric-field sensors. This study investigates the use of an optimized segmented slot waveguide as the core of a sensor to determine the sensor features that produce useful frequency responses and sensitivity. The segmented slot waveguide is optimized in terms of periodicity and segment width to produce low Vπ and electrical bandwidth before testing the sensor sensitivity. The results show that reducing the segment width achieves a low Vπ of 0.32 V and a very low electrical bandwidth of 4.3 kHz. Our study provides evidence of the feasibility of using a segmented slot waveguide as the primary element for highly sensitive, low-frequency AC electric-field sensors.

  20. Conditional Eddies in Plasma Turbulence

    DEFF Research Database (Denmark)

    Johnsen, Helene; Pécseli, Hans; Trulsen, J.

    1986-01-01

    Conditional structures, or eddies, in turbulent flows are discussed with special attention to electrostatic turbulence in plasmas. The potential variation of these eddies is obtained by sampling the fluctuations only when a certain condition is satisfied in a reference point. The resulting...

  1. Diffusion-prepared stimulated-echo turbo spin echo (DPsti-TSE): An eddy current-insensitive sequence for three-dimensional high-resolution and undistorted diffusion-weighted imaging.

    Science.gov (United States)

    Zhang, Qinwei; Coolen, Bram F; Versluis, Maarten J; Strijkers, Gustav J; Nederveen, Aart J

    2017-07-01

    In this study, we present a new three-dimensional (3D), diffusion-prepared turbo spin echo sequence based on a stimulated-echo read-out (DPsti-TSE) enabling high-resolution and undistorted diffusion-weighted imaging (DWI). A dephasing gradient in the diffusion preparation module and rephasing gradients in the turbo spin echo module create stimulated echoes, which prevent signal loss caused by eddy currents. Near to perfect agreement of apparent diffusion coefficient (ADC) values between DPsti-TSE and diffusion-weighted echo planar imaging (DW-EPI) was demonstrated in both phantom transient signal experiments and phantom imaging experiments. High-resolution and undistorted DPsti-TSE was demonstrated in vivo in prostate and carotid vessel wall. 3D whole-prostate DWI was achieved with four b values in only 6 min. Undistorted ADC maps of the prostate peripheral zone were obtained at low and high imaging resolutions with no change in mean ADC values [(1.60 ± 0.10) × 10-3 versus (1.60 ± 0.02) × 10-3  mm2 /s]. High-resolution 3D DWI of the carotid vessel wall was achieved in 12 min, with consistent ADC values [(1.40 ± 0.23) × 10-3  mm2 /s] across different subjects, as well as slice locations through the imaging volume. This study shows that DPsti-TSE can serve as a robust 3D diffusion-weighted sequence and is an attractive alternative to the traditional two-dimensional DW-EPI approaches. Copyright © 2017 John Wiley & Sons, Ltd.

  2. 2010, Eddy County, NM, Current Area Hydrography

    Data.gov (United States)

    Earth Data Analysis Center, University of New Mexico — The TIGER/Line Files are shapefiles and related database files (.dbf) that are an extract of selected geographic and cartographic information from the U.S. Census...

  3. Eddy Current Flow Measurements in the FFTF

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, Deborah L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Polzin, David L. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Omberg, Ronald P. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Makenas, Bruce J. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States)

    2017-02-02

    The Fast Flux Test Facility (FFTF) is the most recent liquid metal reactor (LMR) to be designed, constructed, and operated by the U.S. Department of Energy (DOE). The 400-MWt sodium-cooled, fast-neutron flux reactor plant was designed for irradiation testing of nuclear reactor fuels and materials for liquid metal fast breeder reactors. Following shut down of the Clinch River Breeder Reactor Plant (CRBRP) project in 1983, FFTF continued to play a key role in providing a test bed for demonstrating performance of advanced fuel designs and demonstrating operation, maintenance, and safety of advanced liquid metal reactors. The FFTF Program provides valuable information for potential follow-on reactor projects in the areas of plant system and component design, component fabrication, fuel design and performance, prototype testing, site construction, and reactor control and operations. This report provides HEDL-TC-1344, “ECFM Flow Measurements in the FFTF Using Phase-Sensitive Detectors”, March 1979.

  4. Eddies in the Bay of Biscay: A numerical approximation

    Science.gov (United States)

    Ferrer, Luis; Caballero, Ainhoa

    2011-08-01

    The results of numerical modelling in the Bay of Biscay have been used to investigate eddy dynamics. The modelling has been carried out using mean climatological and atmospheric forcing as input for hydrodynamic simulations with the ROMS model (Regional Ocean Modeling System). The most significant regional circulation features have been simulated in a mesoscale model configuration, with 6.6 km horizontal resolution. Eddy characteristics (horizontal and vertical structure, origins and migration) have been analysed. During winter, jet-like extensions of the slope current off northern Spain (mainly in the vicinity of Cape Ortegal) and France (near Cap Breton, Cap Ferret and Audierne canyons) developed into anticyclonic and cyclonic eddies, with an upper core of slope water. Most of the eddies identified in the model area were anticyclonic, with diameters at sea surface of between 60 and 130 km and significant effects below 500 m in depth. After their generation, the eddies moved slowly westward, with a mean migration speed of less than 2 cm s -1; they dissipated later in the year in the deep basin of the Bay of Biscay. The mean annual surface kinetic energy, estimated with the model, was around 34 cm 2 s -2. Both the kinetic energy and vorticity variability in the study area depend upon changes (magnitude and direction) in the wind stress, which have effects on the development of: the slope poleward current; the Galician upwelling; and the eddy generation and migration.

  5. Mesoscale eddies over the Laptev Sea continental slope in the Arctic Ocean

    Science.gov (United States)

    Pnyushkov, A.; Polyakov, I.; Nguyen, A. T.

    2015-12-01

    Mesoscale eddies are an important component in Arctic Ocean dynamics and can play a role in vertical redistribution of ocean heat from the intermediate layer of warm Atlantic Water (AW). We analyze mooring data collected along the continental slope of the Laptev Sea in 2007-11 to improve the characterization of Arctic mesoscale eddies in this region of the Eurasian Basin (EB).Wavelet analyses suggest that ~20% of the mooring record is occupied by mesoscale eddies, whose vertical scales can be large, often >600 m. Based on similarity between temperature/salinity profiles measured inside eddies and modern climatology for the 2000s, we found two distinct sources of eddy formation in the EB; one in the vicinity of Fram Strait and the other at the continental slope of the Severnaya Zemlya Archipelago. Both sources of eddies are on the route of AW propagation along the EB margins, so that the Arctic Circumpolar Boundary Current (ACBC) can carry these eddies along the continental slope.The lateral advection of waters isolated inside the eddy cores by ACBC affect the heat and salt balance of the eastern EB. The average temperature anomaly inside Fram Strait eddies in the layer above the AW temperature core (i.e., above 350 m depth level) was ~0.1º C with the strongest temperature anomaly in this layer exceeding 0.5ºC. In contrast to Fram Strait eddies, Severnaya Zemlya eddies carry anomalously cold and fresh water, and likely contribute to ventilation of the AW core. In addition, we found increased vertical shears of the horizontal velocities inside eddies that result in enhanced mixing. Our estimates made using the Pacanowski and Philander (1981) relationship suggest that, on average, vertical diffusivity coefficients inside eddies are four times larger than those in the surrounding waters. We will use the high resolution ECCO model to investigate the relative contributions of along and across slope transports induced by eddies along the ACBC path.

  6. Optical current transducer with bulk type Bi12SiO20 faraday sensor for power systems

    Science.gov (United States)

    Katsukawa, Hiroyuki; Yokoi, Seigo

    1997-01-01

    Two types of optical current transducers (OCTs) have a bulk Faraday sensor inserted into the gap of an iron core and a porcelain insulator with optical fiber. The sensor consists of Bi12SiO20 (BSO) single crystal, a polarizer, and an analyzer. The OCTs satisfied the target performance requirement for fault location and metering and demonstrated maintained performance at some power utilities in Japan and the US. We have developed a fault location system that immediately detects the fault current with the OCTs, there by locating the fault section. The OCT can easily replace the existing support insulators for the disconnecting switch without any modifications to structure height or bus-bar. For metering requiring 0.3% class accuracy, use of a BSO with right optical rotatory power combined with BSO with left optical rotatory power results in a Faraday sensor with improved temperature characteristics. The OCT demonstrated 0.3% class accuracy for metering described in the current transformer Specifications of IEEE C57 13, 1993.

  7. Reliability of Sensors Based on Nanowire Networks When the Electrical Current is Allowed to Move in All Directions

    Directory of Open Access Journals (Sweden)

    Nader Ebrahimi

    2014-01-01

    Full Text Available Nanowire networks have great potential in many industrial applications, including batteries, electrical circuits, solar cells, and sensors. In this paper we focus on a specific hydrogen gas nanosensor whose sensing element is a network of palladium nanowires. The nanosensor is modeled using a square, equilateral triangle, and hexagonal lattice. We provide the reliability behavior of this nanosensor when the electrical current is allowed to move in all directions. Our findings reveal an improvement in reliability compared to the scenario where the electrical current could not move from right to left. We show this improvement both analytically and through simulation.

  8. Use of a Secondary Current Sensor in Plasma during Electron-Beam Welding with Focus Scanning for Process Control

    OpenAIRE

    Dmitriy Trushnikov; Elena Krotova; Elena Koleva

    2016-01-01

    We consider questions of building a closed-loop focus control system for electron-beam welding. As a feedback signal, we use the secondary current in the plasma that forms above the welding zone. This article presents a model of a secondary current sensor in plasma during electron-beam welding with focus scanning. A comparison of modeled results with experimental data confirms the adequacy of the model. We show that the best results for focus control are obtained when using phase relationship...

  9. Sensors based on GMR'S for detection of subsurface defects; Sensores basados en GMR's para la deteccion de defectos subsuperficiales

    Energy Technology Data Exchange (ETDEWEB)

    Cordon, J.; Ribes, B.; Vazquez, J.

    2010-07-01

    The use of magneto resistive sensors, GMR, as receptors in eddy current probe has certain advantages over the use of conventional inductive sensors, which puts an alternative for the detection of subsurface defects in metal components with thick materials. It has carried out a study of the most important characteristics of these sensors, which has enabled the manufacture of several probes based on OMR. In this paper we analyze different configurations and present the results of the analysis on several blocks with different defects in materials.

  10. Eddy Correlation Flux Measurement System Handbook

    Energy Technology Data Exchange (ETDEWEB)

    Cook, D. R. [Argonne National Lab. (ANL), Argonne, IL (United States)

    2016-01-01

    The eddy correlation (ECOR) flux measurement system provides in situ, half-hour measurements of the surface turbulent fluxes of momentum, sensible heat, latent heat, and carbon dioxide (CO2) (and methane at one Southern Great Plains extended facility (SGP EF) and the North Slope of Alaska Central Facility (NSA CF). The fluxes are obtained with the eddy covariance technique, which involves correlation of the vertical wind component with the horizontal wind component, the air temperature, the water vapor density, and the CO2 concentration. The instruments used are: • a fast-response, three-dimensional (3D) wind sensor (sonic anemometer) to obtain the orthogonal wind components and the speed of sound (SOS) (used to derive the air temperature) • an open-path infrared gas analyzer (IRGA) to obtain the water vapor density and the CO2 concentration, and • an open-path infrared gas analyzer (IRGA) to obtain methane density and methane flux at one SGP EF and at the NSA CF. The ECOR systems are deployed at the locations where other methods for surface flux measurements (e.g., energy balance Bowen ratio [EBBR] systems) are difficult to employ, primarily at the north edge of a field of crops. A Surface Energy Balance System (SEBS) has been installed collocated with each deployed ECOR system in SGP, NSA, Tropical Western Pacific (TWP), ARM Mobile Facility 1 (AMF1), and ARM Mobile Facility 2 (AMF2). The surface energy balance system consists of upwelling and downwelling solar and infrared radiometers within one net radiometer, a wetness sensor, and soil measurements. The SEBS measurements allow the comparison of ECOR sensible and latent heat fluxes with the energy balance determined from the SEBS and provide information on wetting of the sensors for data quality purposes. The SEBS at one SGP and one NSA site also support upwelling and downwelling PAR measurements to qualify those two locations as Ameriflux sites.

  11. Modeling the dark current histogram induced by gold contamination in complementary-metal-oxide-semiconductor image sensors

    Energy Technology Data Exchange (ETDEWEB)

    Domengie, F., E-mail: florian.domengie@st.com; Morin, P. [STMicroelectronics Crolles 2 (SAS), 850 Rue Jean Monnet, 38926 Crolles Cedex (France); Bauza, D. [CNRS, IMEP-LAHC - Grenoble INP, Minatec: 3, rue Parvis Louis Néel, CS 50257, 38016 Grenoble Cedex 1 (France)

    2015-07-14

    We propose a model for dark current induced by metallic contamination in a CMOS image sensor. Based on Shockley-Read-Hall kinetics, the expression of dark current proposed accounts for the electric field enhanced emission factor due to the Poole-Frenkel barrier lowering and phonon-assisted tunneling mechanisms. To that aim, we considered the distribution of the electric field magnitude and metal atoms in the depth of the pixel. Poisson statistics were used to estimate the random distribution of metal atoms in each pixel for a given contamination dose. Then, we performed a Monte-Carlo-based simulation for each pixel to set the number of metal atoms the pixel contained and the enhancement factor each atom underwent, and obtained a histogram of the number of pixels versus dark current for the full sensor. Excellent agreement with the dark current histogram measured on an ion-implanted gold-contaminated imager has been achieved, in particular, for the description of the distribution tails due to the pixel regions in which the contaminant atoms undergo a large electric field. The agreement remains very good when increasing the temperature by 15 °C. We demonstrated that the amplification of the dark current generated for the typical electric fields encountered in the CMOS image sensors, which depends on the nature of the metal contaminant, may become very large at high electric field. The electron and hole emissions and the resulting enhancement factor are described as a function of the trap characteristics, electric field, and temperature.

  12. Mesoscale eddies in the Subantarctic Front-Southwest Atlantic

    Directory of Open Access Journals (Sweden)

    Pablo D. Glorioso

    2005-12-01

    Full Text Available Satellite and ship observations in the southern southwest Atlantic (SSWA reveal an intense eddy field and highlight the potential for using continuous real-time satellite altimetry to detect and monitor mesoscale phenomena with a view to understanding the regional circulation. The examples presented suggest that mesoscale eddies are a dominant feature of the circulation and play a fundamental role in the transport of properties along and across the Antarctic Circumpolar Current (ACC. The main ocean current in the SSWA, the Falkland-Malvinas Current (FMC, exhibits numerous embedded eddies south of 50°S which may contribute to the patchiness, transport and mixing of passive scalars by this strong, turbulent current. Large eddies associated with meanders are observed in the ACC fronts, some of them remaining stationary for long periods. Two particular cases are examined using a satellite altimeter in combination with in situ observations, suggesting that cross-frontal eddy transport and strong meandering occur where the ACC flow intensifies along the sub-Antarctic Front (SAF and the Southern ACC Front (SACCF.

  13. Iron oxide nanoparticles as magnetic relaxation switching (MRSw) sensors: Current applications in nanomedicine.

    Science.gov (United States)

    Alcantara, David; Lopez, Soledad; García-Martin, María Luisa; Pozo, David

    2016-07-01

    Since pioneering work in the early 60s on the development of enzyme electrodes the field of sensors has evolved to different sophisticated technological platforms. Still, for biomedical applications, there are key requirements to meet in order to get fast, low-cost, real-time data acquisition, multiplexed and automatic biosensors. Nano-based sensors are one of the most promising healthcare applications of nanotechnology, and prone to be one of the first to become a reality. From all nanosensors strategies developed, Magnetic Relaxation Switches (MRSw) assays combine several features which are attractive for nanomedical applications such as safe biocompatibility of magnetic nanoparticles, increased sensitivity/specificity measurements, possibility to detect analytes in opaque samples (unresponsive to light-based interferences) and the use of homogeneous setting assay. This review aims at presenting the ongoing progress of MRSw technology and its most important applications in clinical medicine. Copyright © 2016 Elsevier Inc. All rights reserved.

  14. Medical applications of wireless sensor networks – current status and future directions

    Directory of Open Access Journals (Sweden)

    Krešimir Grgić

    2012-02-01

    Full Text Available In recent years a significant development of BASN (Body AreaSensor Networks as a special subclass of WSN (Wireless SensorNetworks has emerged. These networks have enabled a rapiddevelopment of telemedicine systems, which provide remote monitoringof patients and their vital parameters. The article givesa short overview of the BASN networks. Furthermore, a generalsystem architecture of telemedicine systems is proposed. The proposedarchitecture includes a local sensory area, a communicationnetwork area and an institutional network area. It also providesthe security and privacy of patient-related data. Furthermore, thearticle surveys some existing telemedicine systems. Finally, somecurrent problems are explained and the directions for the futuredevelopment of the telemedicine systems are given.

  15. Estimating smart city sensors data generation: current and future data in the city of Barcelona

    OpenAIRE

    Sinaeepourfard, Amir; García Almiñana, Jordi; Masip Bruin, Xavier; Marín Tordera, Eva; Cirera, J.; G. Grau; Casaus, F.

    2016-01-01

    Nowadays, Smart Cities are positioned as one of the most challenging and important research topics, highlighting major changes in people's lifestyle. Technologies such as smart energy, smart transportation or smart health are being designed to improve citizen's quality of life. Smart Cities leverage the deployment of a network of devices - sensors and mobile devices-, all connected through different means and/or technologies, according to their network availability and capacities, setting a n...

  16. Mapping of the Resistance of a Superconducting Transition Edge Sensor as a Function of Temperature, Current, and Applied Magnetic Field

    Science.gov (United States)

    Zhang, Shou; Eckart, Megan E.; Jaeckel, Felix; Kripps, Kari L.; McCammon, Dan; Zhou, Yu; Morgan, Kelsey M.

    2017-01-01

    We have measured the resistance R (T, I, B(sub ext) of a superconducting transition edge sensor over the entire transition region on a fine scale, producing a four-dimensional map of the resistance surface. The dimensionless temperature and current sensitivities (alpha equivalence partial derivative log R/partial derivative log T|(sub I) and beta equivalence partial derivative log R/partial derivative log I|(sub T) of the TES resistance have been determined at each point. alpha and beta are closely related to the sensor performance, but show a great deal of complex, large amplitude fine structure over large portions of the surface that is sensitive to the applied magnetic field. We discuss the relation of this structure to the presence of Josephson weak link fringes.

  17. Automatic tracking of dynamical evolutions of oceanic mesoscale eddies with satellite observation data

    Science.gov (United States)

    Sun, Liang; Li, Qiu-Yang

    2017-04-01

    The oceanic mesoscale eddies play a major role in ocean climate system. To analyse spatiotemporal dynamics of oceanic mesoscale eddies, the Genealogical Evolution Model (GEM) based on satellite data is developed, which is an efficient logical model used to track dynamic evolution of mesoscale eddies in the ocean. It can distinguish different dynamic processes (e.g., merging and splitting) within a dynamic evolution pattern, which is difficult to accomplish using other tracking methods. To this end, a mononuclear eddy detection method was firstly developed with simple segmentation strategies, e.g. watershed algorithm. The algorithm is very fast by searching the steepest descent path. Second, the GEM uses a two-dimensional similarity vector (i.e. a pair of ratios of overlap area between two eddies to the area of each eddy) rather than a scalar to measure the similarity between eddies, which effectively solves the ''missing eddy" problem (temporarily lost eddy in tracking). Third, for tracking when an eddy splits, GEM uses both "parent" (the original eddy) and "child" (eddy split from parent) and the dynamic processes are described as birth and death of different generations. Additionally, a new look-ahead approach with selection rules effectively simplifies computation and recording. All of the computational steps are linear and do not include iteration. Given the pixel number of the target region L, the maximum number of eddies M, the number N of look-ahead time steps, and the total number of time steps T, the total computer time is O (LM(N+1)T). The tracking of each eddy is very smooth because we require that the snapshots of each eddy on adjacent days overlap one another. Although eddy splitting or merging is ubiquitous in the ocean, they have different geographic distribution in the Northern Pacific Ocean. Both the merging and splitting rates of the eddies are high, especially at the western boundary, in currents and in "eddy deserts". GEM is useful not only for

  18. Inductive sensors for blade tip-timing in gas turbines

    Directory of Open Access Journals (Sweden)

    Przysowa Radosław

    2015-12-01

    Full Text Available The paper reviews features and applications of the upgraded inductive sensor for BTT, which is able to operate in contact with exhaust gases of temperature even as high as 1200 K. The new design includes metal-ceramic housing ensuring proper heat transfer, magnetic circuit containing set of permanent magnets with various magnetic field values and Curie temperatures, completely redesigned windings and current/voltage converter used instead of an electromotive force amplifier. Its principle of operation is based on electro-dynamical interaction and therefore it may be referred as a passive eddy-current sensor. The sensor technique has been demonstrated on four stages of a surplus military turbofan including the high pressure turbine as part of the engine health monitoring system. We present signal samples and review methods used for online processing of time-of-arrival signals when only a limited number of sensors is available.

  19. Arctic North Atlantic Water pathways and heat fluxes in Eddy-Admitting and Eddy-Permitting Global Ocean Simulations

    Science.gov (United States)

    Aksenov, Yevgeny; Kelly, Stephen; Popova, Ekaterina; Bacon, Sheldon; Nurser, A. J. George; Yool, Andrew; Coward, Andrew C.

    2017-04-01

    Results from the model tracer releases in global NEMO configurations at 1/4 and 1/12 degree resolution are presented. We examine North Atlantic water (NAW) inflows in the Arctic Ocean in the models in "eddying" regimes and investigate the role of the eddies in the NAW dynamics and heat transports. In the model experiments the NAW tracers have been released in the eastern Fram Strait and the western Barents Sea and traced in the Arctic Ocean and Nordic Sea for the 2000-2015. The model results demonstrate that NAW follows continental shelf slopes within the Arctic Boundary Current and also flows across the shelf slopes in the Arctic Ocean, with the eddy transport being a principal mechanism for the NAW spread. We investigate cascading of the dense northern Barents Sea water into the deep Arctic Ocean, which is another mechanism to transport the modified NAW into the deep Arctic Ocean. The study quantifies eddy heat fluxes across Siberian shelf slopes towards the central Arctic Ocean. By comparing the eddying runs with the similar runs at a lower resolution, the study highlights difference in the NAW model dynamics due to eddy resolving model capabilities.

  20. Evolution of physical and biological characteristics of mesoscale eddy in north-central Red Sea

    KAUST Repository

    Zarokanellos, Nikolaos

    2015-04-01

    Eddies appear to be important to both the physical and biogeochemical dynamics of the Red Sea. Numerical simulations of physical dynamics and remote sensing studies of chlorophyll concentration and sea surface height in the Red Sea indicate their importance to the upper portions of the sea (Raitsos et al., 2013; Yao et al., 2014; Zhan et al., 2014). Despite their apparent importance, process studies of these eddies have been lacking. In March 2013 we began an extended observational study of the north-central Red Sea (NCRS) where anticyclonic eddies have been observed. The study began with a ship-based characterization of the eddy and was followed by a three-month observational time series using an autonomous glider equipped with a CTD, oxygen sensor, and optical sensors for chlorophyll, CDOM and optical backscatter. The ship-based study captured an initial snapshot of an anticyclonic eddy and it\\'s associated biological and bio-optical distributions. Initially, chlorophyll distributions tended to mirror the density distribution, with deeper isopycnals and chlorophyll maximum depth in the anticyclonic eddy center. The anticyclone eddy in March had an along basin diameter of 150 km, penetrated vertically less than 150 m and elevated near surface chlorophyll concentrations appeared along its outer boundary. The shallowing of the pycnocline of the outer boundaries of the anticyclone eddy on March may elevate nutrients into the lower euphotic zone, contributing to phytoplankton productivity and biomass within the eddy. This eddy contains most of the kinetic energy of the region with the maximum velocities up to 30 - 35 cm/s. The eddy appeared to interact with the coastal reefs where exchange particulate and dissolved matter may occur. The autonomous glider provided the spring-to-summer progression of the system with increasing stratification, shallowing of the subsurface chlorophyll maximum, and fluctuations in the position and intensity of the eddy. Our glider effort

  1. submitter Estimation of stepping motor current from long distances through cable-length-adaptive piecewise affine virtual sensor

    CERN Document Server

    Oliveri, Alberto; Masi, Alessandro; Storace, Marco

    2015-01-01

    In this paper a piecewise affine virtual sensor is used for the estimation of the motor-side current of hybrid stepper motors, which actuate the LHC (Large Hadron Collider) collimators at CERN. The estimation is performed starting from measurements of the current in the driver, which is connected to the motor by a long cable (up to 720 m). The measured current is therefore affected by noise and ringing phenomena. The proposed method does not require a model of the cable, since it is only based on measured data and can be used with cables of different length. A circuit architecture suitable for FPGA implementation has been designed and the effects of fixed point representation of data are analyzed.

  2. Use of a Secondary Current Sensor in Plasma during Electron-Beam Welding with Focus Scanning for Process Control

    Directory of Open Access Journals (Sweden)

    Dmitriy Trushnikov

    2016-01-01

    Full Text Available We consider questions of building a closed-loop focus control system for electron-beam welding. As a feedback signal, we use the secondary current in the plasma that forms above the welding zone. This article presents a model of a secondary current sensor in plasma during electron-beam welding with focus scanning. A comparison of modeled results with experimental data confirms the adequacy of the model. We show that the best results for focus control are obtained when using phase relationships rather than amplitude relationships. We outline the principles for building an EBW focus control system based on parameters of the secondary current in plasma. We simulate the work of a control system’s circuits and demonstrate the stability of the synthesized system. We have conducted pilot tests on an experimental prototype.

  3. Agulhas Current variability determined from space: a multi-sensor approach

    CSIR Research Space (South Africa)

    Rouault, M

    2011-11-01

    Full Text Available with the Agulhas Current also provides an ideal natural laboratory for testing and developing new remote sensing products. 2 1.2. OBJECTIVES AND APPROACH 1.2 Objectives and approach The Agulhas Current system is a challenging environment for remote sensing...];Bryden et al. [2005]). Statistical and time-series analysis of suitable remotely sensed data will be used to test the hypothesis that Natal Pulses dominate the variability of the Agulhas Current. Is there a seasonal cycle in the Agulhas Current...

  4. A Low-Power Wide Dynamic-Range Current Readout Circuit for Ion-Sensitive FET Sensors.

    Science.gov (United States)

    Son, Hyunwoo; Cho, Hwasuk; Koo, Jahyun; Ji, Youngwoo; Kim, Byungsub; Park, Hong-June; Sim, Jae-Yoon

    2017-06-01

    This paper presents an amplifier-less and digital-intensive current-to-digital converter for ion-sensitive FET sensors. Capacitance on the input node is utilized as a residue accumulator, and a clocked comparator is followed for quantization. Without any continuous-time feedback circuit, the converter performs a first-order noise shaping of the quantization error. In order to minimize static power consumption, the proposed circuit employs a single-ended current-steering digital-to-analog converter which flows only the same current as the input. By adopting a switching noise averaging algorithm, our dynamic element matching not only mitigates mismatch of current sources in the current-steering DAC, but also makes the effect of dynamic switching noise become an input-independent constant. The implemented circuit in 0.35 μm CMOS converts the current input with a range of 2.8 μ A to 15 b digital output in about 4 ms, showing a DNL of +0.24/-0.25 LSB and an INL of + 1.98/-1.98 LSB while consuming 16.8 μW.

  5. Subregional characterization of mesoscale eddies across the Brazil-Malvinas Confluence

    Science.gov (United States)

    Mason, Evan; Pascual, Ananda; Gaube, Peter; Ruiz, Simón; Pelegrí, Josep L.; Delepoulle, Antoine

    2017-04-01

    Horizontal and vertical motions associated with coherent mesoscale structures, including eddies and meanders, are responsible for significant global transports of many properties, including heat and mass. Mesoscale vertical fluxes also influence upper ocean biological productivity by mediating the supply of nutrients into the euphotic layer, with potential impacts on the global carbon cycle. The Brazil-Malvinas Confluence (BMC) is a western boundary current region in the South Atlantic with intense mesoscale activity. This region has an active role in the genesis and transformation of water masses and thus is a critical component of the Atlantic meridional overturning circulation. The collision between the Malvinas and Brazil Currents over the Patagonian shelf/slope creates an energetic front that translates offshore to form a vigorous eddy field. Recent improvements in gridded altimetric sea level anomaly fields allow us to track BMC mesoscale eddies with high spatial and temporal resolutions using an automated eddy tracker. We characterize the eddies across fourteen 5° × 5° subregions. Eddy-centric composites of tracers and geostrophic currents diagnosed from a global reanalysis of surface and in situ data reveal substantial subregional heterogeneity. The in situ data are also used to compute the evolving quasi-geostrophic vertical velocity (QG-ω) associated with each instantaneous eddy instance. The QG-ω eddy composites have the expected dipole patterns of alternating upwelling/downwelling, however, the magnitude and sign of azimuthally averaged vertical velocity varies among subregions. Maximum eddy values are found near fronts and sharp topographic gradients. In comparison with regional eddy composites, subregional composites provide refined information about mesoscale eddy heterogeneity.

  6. A Very Low Dark Current Temperature-Resistant, Wide Dynamic Range, Complementary Metal Oxide Semiconductor Image Sensor

    Science.gov (United States)

    Mizobuchi, Koichi; Adachi, Satoru; Tejada, Jose; Oshikubo, Hiromichi; Akahane, Nana; Sugawa, Shigetoshi

    2008-07-01

    A very low dark current (VLDC) temperature-resistant approach which best suits a wide dynamic range (WDR) complementary metal oxide semiconductor (CMOS) image sensor with a lateral over-flow integration capacitor (LOFIC) has been developed. By implementing a low electric field photodiode without a trade-off of full well-capacity, reduced plasma damage, re-crystallization, and termination of silicon-silicon dioxide interface states in the front end of line and back end of line (FEOL and BEOL) in a 0.18 µm, two polycrystalline silicon, three metal (2P3M) process, the dark current is reduced to 11 e-/s/pixel (0.35 e-/s/µm2: pixel area normalized) at 60 °C, which is the lowest value ever reported. For further robustness at low and high temperatures, 1/3-in., 5.6-µm pitch, 800×600 pixel sensor chips with low noise readout circuits designed for a signal and noise hold circuit and a programmable gain amplifier (PGA) have also been deposited with an inorganic cap layer on a micro-lens and covered with a metal hermetically sealed package assembly. Image sensing performance results in 2.4 e-rms temporal noise and 100 dB dynamic range (DR) with 237 ke- full well-capacity. The operating temperature range is extended from -40 to 85 °C while retaining good image quality.

  7. The signature of mesoscale eddies on the air-sea turbulent heat fluxes in the South Atlantic Ocean

    Science.gov (United States)

    Villas Bôas, A. B.; Sato, O. T.; Chaigneau, A.; Castelão, G. P.

    2015-03-01

    By collocating 10 years (1999-2009) of remotely sensed surface turbulent heat fluxes with satellite altimetry data, we investigate the impact of oceanic mesoscale eddies on the latent and sensible heat fluxes in the South Atlantic Ocean. In strongly energetic regions, such as the Brazil-Malvinas confluence and the Agulhas Current Retroflection, eddies explain up to 20% of the total variance in the surface turbulent heat fluxes with averaged anomalies of ± (10-20) W/m2. Cyclonic (anticyclonic, respectively) eddies are associated with negative (positive) heat flux anomalies that tend to cool (warm) the marine atmospheric boundary layer. A composite analysis of the turbulent heat flux anomalies inside the eddies reveals a direct relationship between eddy amplitude and the intensity of such anomalies. In addition, these anomalies are stronger near the eddy center, decaying radially to reach minimum values outside the eddies.

  8. A High-Sensitivity Current Sensor Utilizing CrNi Wire and Microfiber Coils

    Directory of Open Access Journals (Sweden)

    Xiaodong Xie

    2014-05-01

    Full Text Available We obtain an extremely high current sensitivity by wrapping a section of microfiber on a thin-diameter chromium-nickel wire. Our detected current sensitivity is as high as 220.65 nm/A2 for a structure length of only 35 μm. Such sensitivity is two orders of magnitude higher than the counterparts reported in the literature. Analysis shows that a higher resistivity or/and a thinner diameter of the metal wire may produce higher sensitivity. The effects of varying the structure parameters on sensitivity are discussed. The presented structure has potential for low-current sensing or highly electrically-tunable filtering applications.

  9. Mesoscale eddies: hotspots of prokaryotic activity and differential community structure in the ocean.

    Science.gov (United States)

    Baltar, Federico; Arístegui, Javier; Gasol, Josep M; Lekunberri, Itziar; Herndl, Gerhard J

    2010-08-01

    To investigate the effects of mesoscale eddies on prokaryotic assemblage structure and activity, we sampled two cyclonic eddies (CEs) and two anticyclonic eddies (AEs) in the permanent eddy-field downstream the Canary Islands. The eddy stations were compared with two far-field (FF) stations located also in the Canary Current, but outside the influence of the eddy field. The distribution of prokaryotic abundance (PA), bulk prokaryotic heterotrophic activity (PHA), various indicators of single-cell activity (such as nucleic acid content, proportion of live cells, and fraction of cells actively incorporating leucine), as well as bacterial and archaeal community structure were determined from the surface to 2000 m depth. In the upper epipelagic layer (0-200 m), the effect of eddies on the prokaryotic community was more apparent, as indicated by the higher PA, PHA, fraction of living cells, and percentage of active cells incorporating leucine within eddies than at FF stations. Prokaryotic community composition differed also between eddy and FF stations in the epipelagic layer. In the mesopelagic layer (200-1000 m), there were also significant differences in PA and PHA between eddy and FF stations, although in general, there were no clear differences in community composition or single-cell activity. The effects on prokaryotic activity and community structure were stronger in AE than CE, decreasing with depth in both types of eddies. Overall, both types of eddies show distinct community compositions (as compared with FF in the epipelagic), and represent oceanic 'hotspots' of prokaryotic activity (in the epi- and mesopelagic realms).

  10. Southern Ocean Eddy Heat Flux and Eddy-Mean Flow Interactions in Drake Passage

    Science.gov (United States)

    Foppert, Annie

    The Antarctic Circumpolar Current (ACC) is a complex current system composed of multiple jets that is both unique to the world's oceans and relatively under observed compared with other current systems. Observations taken by current- and pressure-recording inverted echo sounders (CPIES) over four years, from November 2007 to November 2011, quantify the mean structure of one of the main jets of the ACC - the Polar Front - in a composite-mean sense. While the array of CPIES deployed in Drake Passage included a 3 x 7 local dynamics array, analysis of the Polar Front makes use of the line of CPIES that spanned the width of Drake Passage (C-Line). The Polar Front tends to prefer one of two locations, separated along the C-Line by 1° of latitude, with the core of the jet centered on corresponding geopotential height contours (with a 17 cm dierence between the northern and southern jets). Potential vorticity fields suggest that the Polar Front is susceptible to baroclinic instability, regardless of whether it is found upstream (farther south along the C-Line) or downstream (farther north along the C-Line) of the Shackleton Fracture Zone (SFZ), yet the core of the jet remains a barrier to smaller-scale mixing, as inferred from estimated mixing lengths. Within the local dynamics array of CPIES, the observed offset between eddy heat flux (EHF) and eddy kinetic energy (EKE) and the alignment of EHF with sea surface height (SSH) standard deviation motivates a proxy for depth-integrated EHF that can be estimated from available satellite SSH data. An eddy-resolving numerical model develops the statistics of a logarithmic fit between SSH standard deviation and cross-frontal EHF that is applied to the ACC in a circumglobal sense. We find 1.06 PW enters the ACC from the north and 0.02 PW exits towards Antarctica. The magnitude of the estimated EHF, along with contemporaneous estimates of the mean heat flux, suggests that the air-sea heat flux south of the PF is an overestimate

  11. Fiber loop ringdown - a time-domain sensing technique for multi-function fiber optic sensor platforms: current status and design perspectives.

    Science.gov (United States)

    Wang, Chuji

    2009-01-01

    Fiber loop ringdown (FLRD) utilizes an inexpensive telecommunications light source, a photodiode, and a section of single-mode fiber to form a uniform fiber optic sensor platform for sensing various quantities, such as pressure, temperature, strain, refractive index, chemical species, biological cells, and small volume of fluids. In FLRD, optical losses of a light pulse in a fiber loop induced by changes in a quantity are measured by the light decay time constants. FLRD measures time to detect a quantity; thus, FLRD is referred to as a time-domain sensing technique. FLRD sensors have near real-time response, multi-pass enhanced high-sensitivity, and relatively low cost (i.e., without using an optical spectral analyzer). During the last eight years since the introduction of the original form of fiber ringdown spectroscopy, there has been increasing interest in the FLRD technique in fiber optic sensor developments, and new application potential is being explored. This paper first discusses the challenging issues in development of multi-function, fiber optic sensors or sensor networks using current fiber optic sensor sensing schemes, and then gives a review on current fiber optic sensor development using FLRD technique. Finally, design perspectives on new generation, multi-function, fiber optic sensor platforms using FLRD technique are particularly presented.

  12. Thin film metallic sensors in an alternating magnetic field for magnetic nanoparticle hyperthermia cancer therapy

    Science.gov (United States)

    Hussein, Z. A.; Boekelheide, Z.

    In magnetic nanoparticle hyperthermia in an alternating magnetic field for cancer therapy, it is important to monitor the temperature in situ. This can be done optically or electrically, but electronic measurements can be problematic because conducting parts heat up in a changing magnetic field. Microfabricated thin film sensors may be advantageous because eddy current heating is a function of size, and are promising for further miniaturization of sensors and fabrication of arrays of sensors. Thin films could also be used for in situ magnetic field sensors or for strain sensors. For a proof of concept, we fabricated a metallic thin film resistive thermometer by photolithographically patterning a 500Å Au/100Å Cr thin film on a glass substrate. Measurements were taken in a solenoidal coil supplying 0.04 T (rms) at 235 kHz with the sensor parallel and perpendicular to the magnetic field. In the parallel orientation, the resistive thermometer mirrored the background heating from the coil, while in the perpendicular orientation self-heating was observed due to eddy current heating of the conducting elements by Faraday's law. This suggests that metallic thin film sensors can be used in an alternating magnetic field, parallel to the field, with no significant self-heating.

  13. Currently Commercially Available Chemical Sensors Employed for Detection of Volatile Organic Compounds in Outdoor and Indoor Air

    OpenAIRE

    Bartosz Szulczyński; Jacek Gębicki

    2017-01-01

    The paper presents principle of operation and design of the most popular chemical sensors for measurement of volatile organic compounds (VOCs) in outdoor and indoor air. It describes the sensors for evaluation of explosion risk including pellistors and IR-absorption sensors as well as the sensors for detection of toxic compounds such as electrochemical (amperometric), photoionization and semiconductor with solid electrolyte ones. Commercially available sensors for detection of VOCs and their ...

  14. Gas stream analysis using voltage-current time differential operation of electrochemical sensors

    Energy Technology Data Exchange (ETDEWEB)

    Woo, Leta Yar-Li; Glass, Robert Scott; Fitzpatrick, Joseph Jay; Wang, Gangqiang; Henderson, Brett Tamatea; Lourdhusamy, Anthoniraj; Steppan, James John; Allmendinger, Klaus Karl

    2018-01-02

    A method for analysis of a gas stream. The method includes identifying an affected region of an affected waveform signal corresponding to at least one characteristic of the gas stream. The method also includes calculating a voltage-current time differential between the affected region of the affected waveform signal and a corresponding region of an original waveform signal. The affected region and the corresponding region of the waveform signals have a sensitivity specific to the at least one characteristic of the gas stream. The method also includes generating a value for the at least one characteristic of the gas stream based on the calculated voltage-current time differential.

  15. Energy Cascade Analysis: from Subscale Eddies to Mean Flow

    Science.gov (United States)

    Cheikh, Mohamad Ibrahim; Wonnell, Louis; Chen, James

    2017-11-01

    Understanding the energy transfer between eddies and mean flow can provide insights into the energy cascade process. Much work has been done to investigate the energy cascade at the level of the smallest eddies using different numerical techniques derived from the Navier-Stokes equations. These methodologies, however, prove to be computationally inefficient when producing energy spectra for a wide range of length scales. In this regard, Morphing Continuum Theory (MCT) resolves the length-scales issues by assuming the fluid continuum to be composed of inner structures that play the role of subscale eddies. The current study show- cases the capabilities of MCT in capturing the dynamics of energy cascade at the level of subscale eddies, through a supersonic turbulent flow of Mach 2.93 over an 8× compression ramp. Analysis of the results using statistical averaging procedure shows the existence of a statistical coupling of the internal and translational kinetic energy fluctuations with the corresponding rotational kinetic energy of the subscale eddies, indicating a multiscale transfer of energy. The results show that MCT gives a new characterization of the energy cascade within compressible turbulence without the use of excessive computational resources. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-17-1-0154.

  16. Single-current-sensor-based active front-end-converter-fed four ...

    Indian Academy of Sciences (India)

    Joseph Kiran Banda

    fast acting digital signal processors, which has created a revolution in the area of electrical drives. Even though ... currents, which results in AC quantities transforming into. DC quantities by decoupling into torque and flux .... angle of transformation obtained, a reference voltage at desired phase is generated using a voltage ...

  17. Model and performance of current sensor observers for a doubly fed induction generator

    DEFF Research Database (Denmark)

    Li, Hui; Yang, Chao; Hu, Yaogang

    2014-01-01

    This article presents a stator and rotor current observer for a doubly fed induction generator. First, the dynamic models of the wind turbine drive train are presented, and the vector control strategies of a doubly fed induction generator for the rotor-side and grid-side converters are described....

  18. Eddy diffusivity in the ocean surface

    Science.gov (United States)

    Redondo, Jose M.; Castilla, Robert; Platonov, Alexei

    2010-05-01

    In order to measure eddy diffusivity in the ocean using a scaling that includes the thickness of the surf zone as well as the depth and the wave period[1,2]. Measurements in the Mediterranean are almost two orders of magnitude smaller than in the Pacific coast. On a larger scale, and further away from the coast the relevant eddy diffusivities are much larger, because large eddies often scale on the Rossby deformation radius, LR. Direct measurements of the diffusion and the horizontal velocity field were performed at several sites in the coastal areas of Spain. The diffusion coeficients were calculated by evaluation from video images of the area of milk and fluoresceine blobs released at different positions and with different wave heights, wind speeds and tidal induced currents[1-3]. There are instances with either low hipo-diffusivity or high hyper-diffusivity and local measurements in both cases indicate that spectra deviate strongly from an equilibrium spectrum. A generalized Richardson law [3,4] deduced from Kinematic Simulation (KS) numerical models may be applied also to coastal diffusion[5]. The eddy viscosity values show a complex behaviour that depends on wind friction, wave induced Reynolds number and flow topology. The results of more than 100 experiments show that there is a dependence of the maximum diffusivity on a Reynolds number derived from the wave height[1]. The increase of diffusivity with wave height only occurs for large enough wave Reynolds numbers. Other important factors are wind speed and tidal currents. The horizontal diffusivity shows also a marked anisotropy and spectral dependence [4,6]. [1] M. Diez, M. O. Bezerra, C. Mosso, R. Castilla and J. M. Redondo,Experimental measurements and diffusion in harbor and coastal zones. Il Nuovo Cimento Vol. 31 C, N. 5-6 Settembre-Dicembre (2008), 843. [2] Carrillo A., Sanchez M. A., Platonov A. and Redondo J. M., Phys. Chem. Earth B, 26. 4 (2001) 305. [3] Redondo J. M., Sanchez M. A. and Castilla R

  19. Pixel pitch and particle energy influence on the dark current distribution of neutron irradiated CMOS image sensors.

    Science.gov (United States)

    Belloir, Jean-Marc; Goiffon, Vincent; Virmontois, Cédric; Raine, Mélanie; Paillet, Philippe; Duhamel, Olivier; Gaillardin, Marc; Molina, Romain; Magnan, Pierre; Gilard, Olivier

    2016-02-22

    The dark current produced by neutron irradiation in CMOS Image Sensors (CIS) is investigated. Several CIS with different photodiode types and pixel pitches are irradiated with various neutron energies and fluences to study the influence of each of these optical detector and irradiation parameters on the dark current distribution. An empirical model is tested on the experimental data and validated on all the irradiated optical imagers. This model is able to describe all the presented dark current distributions with no parameter variation for neutron energies of 14 MeV or higher, regardless of the optical detector and irradiation characteristics. For energies below 1 MeV, it is shown that a single parameter has to be adjusted because of the lower mean damage energy per nuclear interaction. This model and these conclusions can be transposed to any silicon based solid-state optical imagers such as CIS or Charged Coupled Devices (CCD). This work can also be used when designing an optical imager instrument, to anticipate the dark current increase or to choose a mitigation technique.

  20. A subsurface cyclonic eddy in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Babu, M.T.; PrasannaKumar, S.; Rao, D.P.

    and to a larger extent from the action of wind stress curl while in the southern part the northward current is purely wind-driven. High stratification causEd. by fresh water influx prevented the eddy from being detected at the surface....

  1. Electrical and mechanical performance difference on piezoelectric segmentation in a passive MEMS DC current sensor applicable to two-wire DC appliances

    Science.gov (United States)

    Yang, Xu; Fu, Yupeng; Wang, Dong F.

    2017-01-01

    As society develops in intelligence, DC is being widely used in all kinds of field in modern life, which means that a sensitive and convenient DC sensor is necessary to monitor it. Compared with other kinds of current sensor, the proposed passive MEMS DC current sensor has several significant features: power-free passive sensing, small size and low cost. In this work, the performance difference of a cantilever-based bending MEMS DC current sensor among three segmentation PZT plates was first experimentally discovered. The distribution difference of X-dir (X-direction) stress along the Y axis is confirmed through FEM analysis. An optimized structure with two slots at the root of the cantilever has been proposed to minimize the difference of average X-dir stress on an area attached to three PZT plates. A nearly linear relationship between the output voltage V output and the AC current has been obtained through both theoretical calculation and experimental verification. The sensitivity of the developed MEMS DC current sensor is 40-25 mV A-1 in the current range of 0-400 mA. It is found that there is a good consistency among the calculation, experiment and simulation results.

  2. Currently Commercially Available Chemical Sensors Employed for Detection of Volatile Organic Compounds in Outdoor and Indoor Air

    Directory of Open Access Journals (Sweden)

    Bartosz Szulczyński

    2017-03-01

    Full Text Available The paper presents principle of operation and design of the most popular chemical sensors for measurement of volatile organic compounds (VOCs in outdoor and indoor air. It describes the sensors for evaluation of explosion risk including pellistors and IR-absorption sensors as well as the sensors for detection of toxic compounds such as electrochemical (amperometric, photoionization and semiconductor with solid electrolyte ones. Commercially available sensors for detection of VOCs and their metrological parameters—measurement range, limit of detection, measurement resolution, sensitivity and response time—were presented. Moreover, development trends and prospects of improvement of the metrological parameters of these sensors were highlighted.

  3. Direct electrochemical sensor for label-free DNA detection based on zero current potentiometry.

    Science.gov (United States)

    Wu, Nai-ying; Gao, Wei; He, Xu-lun; Chang, Zhu; Xu, Mao-tian

    2013-01-15

    A direct electrochemical DNA biosensor based on zero current potentiometry was fabricated by immobilization of ssDNA onto gold nanoparticles (AuNPs) coated pencil graphite electrode (PGE). One ssDNA/AuNPs/PGE was connected in series between clips of working and counter electrodes of a potentiostat, and then immersed into the solution together with a reference electrode, establishing a novel DNA biosensor for specific DNA detection. The variation of zero current potential difference (ΔE(zcp)) before and after hybridization of the self-assembled probe DNA with the target DNA was used as a signal to characterize and quantify the target DNA sequence. The whole DNA biosensor fabrication process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy with the use of ferricyanide as an electrochemical redox indicator. Under the optimized conditions, ΔE(zcp) was linear with the concentrations of the complementary target DNA in the range from 10nM to 1μM, with a detection limit of 6.9nM. The DNA biosensor showed a good reproducibility and selectivity. Prepared DNA biosensor is facile and sensitive, and it eliminates the need of using exogenous reagents to monitor the oligonucleotides hybridization. Copyright © 2012 Elsevier B.V. All rights reserved.

  4. Observation of Oceanic Eddy in the Northeastern Arabian Sea Using Multisensor Remote Sensing Data

    Directory of Open Access Journals (Sweden)

    R. K. Sarangi

    2012-01-01

    Full Text Available An oceanic eddy of size about 150 kilometer diameter observed in the northeastern Arabian Sea using remote sensing satellite sensors; IRS-P4 OCM, NOAA-AVHRR and NASA Quickscat Scatterometer data. The eddy was detected in the 2nd week of February in Indian Remote Sensing satellite (IRS-P4 Ocean Color Monitor (OCM sensor retrieved chlorophyll image on 10th February 2002, between latitude 16°90′–18°50′N and longitude 66°05′–67°60′E. The chlorophyll concentration was higher in the central part of eddy (~1.5 mg/m3 than the peripheral water (~0.8 mg/m3. The eddy lasted till 10th March 2002. NOAA-AVHRR sea surface temperature (SST images generated during 15th February-15th March 2002. The SST in the eddy’s center (~23°C was lesser than the surrounding water (~24.5°C. The eddy was of cold core type with the warmer water in periphery. Quickscat Scatterometer retrieved wind speed was 8–10 m/sec. The eddy movement observed southeast to southwest direction and might helped in churning. The eddy seemed evident due to convective processes in water column. The processes like detrainment and entrainment play role in bringing up the cooler water and the bottom nutrient to surface and hence the algal blooming. This type of cold core/anti-cyclonic eddy is likely to occur during late winter/spring as a result of the prevailing climatic conditions.

  5. Replacement Condition Detection of Railway Point Machines Using an Electric Current Sensor

    Science.gov (United States)

    Sa, Jaewon; Choi, Younchang; Chung, Yongwha; Kim, Hee-Young; Park, Daihee; Yoon, Sukhan

    2017-01-01

    Detecting replacement conditions of railway point machines is important to simultaneously satisfy the budget-limit and train-safety requirements. In this study, we consider classification of the subtle differences in the aging effect—using electric current shape analysis—for the purpose of replacement condition detection of railway point machines. After analyzing the shapes of after-replacement data and then labeling the shapes of each before-replacement data, we can derive the criteria that can handle the subtle differences between “does-not-need-to-be-replaced” and “needs-to-be-replaced” shapes. On the basis of the experimental results with in-field replacement data, we confirmed that the proposed method could detect the replacement conditions with acceptable accuracy, as well as provide visual interpretability of the criteria used for the time-series classification. PMID:28146057

  6. Replacement Condition Detection of Railway Point Machines Using an Electric Current Sensor.

    Science.gov (United States)

    Sa, Jaewon; Choi, Younchang; Chung, Yongwha; Kim, Hee-Young; Park, Daihee; Yoon, Sukhan

    2017-01-29

    Detecting replacement conditions of railway point machines is important to simultaneously satisfy the budget-limit and train-safety requirements. In this study, we consider classification of the subtle differences in the aging effect-using electric current shape analysis-for the purpose of replacement condition detection of railway point machines. After analyzing the shapes of after-replacement data and then labeling the shapes of each before-replacement data, we can derive the criteria that can handle the subtle differences between "does-not-need-to-be-replaced" and "needs-to-be-replaced" shapes. On the basis of the experimental results with in-field replacement data, we confirmed that the proposed method could detect the replacement conditions with acceptable accuracy, as well as provide visual interpretability of the criteria used for the time-series classification.

  7. Sensor networks

    NARCIS (Netherlands)

    Chatterjea, Supriyo; Thurston, J.; Kininmonth, S.; Havinga, Paul J.M.

    2006-01-01

    This article describes the details of a sensor network that is currently being deployed at the Great Barrier Reef in Australia. The sensor network allows scientists to retrieve sensor data that has a high spatial and temporal resolution. We give an overview of the energy-efficient data aggregation

  8. Isoprene flux measurements using eddy covariance and disjunct eddy accumulation

    Science.gov (United States)

    Pressley, S. N.; Lamb, B.; Westberg, H.; Allwine, G.; Turnipseed, A.; Guenther, A.

    2005-12-01

    Quantifying biogenic hydrocarbon (BHC) emissions is important for understanding the role they play in tropospheric chemistry. Isoprene is a very reactive compound that affects the oxidative capacity of the atmosphere, which in turn determines the lifetime of numerous atmospheric constituents such as methane (CH4) and CO. The oxidation of isoprene leads to the production of peroxy radicals (RO2), which may lead to the formation of organic acids, or depending on the level of nitric oxides present, to either production or consumption of tropospheric O3. BHC emissions, in particular isoprene, are predominantly driven by increases in temperature and solar radiation, and there can be significant variations in emissions from one hour to the next, and between days. To better understand the natural variability of isoprene emissions, eddy covariance isoprene flux measurements are being collected on a long-term basis. This long-term dataset, spanning from 1999-2005, provides a unique tool for validating biogenic emission inventories that are used as input into regional photochemical models. This long-term dataset will be presented and compared to the biogenic emission inventory system (BEIS3) model estimates. Using isoprene as a compound of interest, the micrometeorological technique of disjunct eddy accumulation (DEA) was tested side-by-side with the direct eddy covariance (EC) technique. One week of DEA and EC hourly flux measurements will be presented, confirming the use of DEA to measure fluxes of other atmospheric compounds that, to date, has not been attainable.

  9. High-Compression-Ratio; Atkinson-Cycle Engine Using Low-Pressure Direct Injection and Pneumatic-Electronic Valve Actuation Enabled by Ionization Current and Foward-Backward Mass Air Flow Sensor Feedback

    Energy Technology Data Exchange (ETDEWEB)

    Harold Schock; Farhad Jaberi; Ahmed Naguib; Guoming Zhu; David Hung

    2007-12-31

    This report describes the work completed over a two and one half year effort sponsored by the US Department of Energy. The goal was to demonstrate the technology needed to produce a highly efficient engine enabled by several technologies which were to be developed in the course of the work. The technologies included: (1) A low-pressure direct injection system; (2) A mass air flow sensor which would measure the net airflow into the engine on a per cycle basis; (3) A feedback control system enabled by measuring ionization current signals from the spark plug gap; and (4) An infinitely variable cam actuation system based on a pneumatic-hydraulic valve actuation These developments were supplemented by the use of advanced large eddy simulations as well as evaluations of fuel air mixing using the KIVA and WAVE models. The simulations were accompanied by experimental verification when possible. In this effort a solid base has been established for continued development of the advanced engine concepts originally proposed. Due to problems with the valve actuation system a complete demonstration of the engine concept originally proposed was not possible. Some of the highlights that were accomplished during this effort are: (1) A forward-backward mass air flow sensor has been developed and a patent application for the device has been submitted. We are optimistic that this technology will have a particular application in variable valve timing direct injection systems for IC engines. (2) The biggest effort on this project has involved the development of the pneumatic-hydraulic valve actuation system. This system was originally purchased from Cargine, a Swedish supplier and is in the development stage. To date we have not been able to use the actuators to control the exhaust valves, although the actuators have been successfully employed to control the intake valves. The reason for this is the additional complication associated with variable back pressure on the exhaust valves when

  10. Estimates of vertical velocities and eddy coefficients in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Varkey, M.J.; Sastry, J.S.

    Vertical velocities and eddy coefficients in the intermediate depths of the Bay of Bengal are calculated from mean hydrographic data for 300 miles-squares. The linear current density (sigma- O) versus log-depth plots show steady balance between...

  11. Metamaterial Sensors

    Directory of Open Access Journals (Sweden)

    Jing Jing Yang

    2013-01-01

    Full Text Available Metamaterials have attracted a great deal of attention due to their intriguing properties, as well as the large potential applications for designing functional devices. In this paper, we review the current status of metamaterial sensors, with an emphasis on the evanescent wave amplification and the accompanying local field enhancement characteristics. Examples of the sensors are given to illustrate the principle and the performance of the metamaterial sensor. The paper concludes with an optimistic outlook regarding the future of metamaterial sensor.

  12. Uncertainty in eddy covariance flux estimates resulting from spectral attenuation [Chapter 4

    Science.gov (United States)

    W. J. Massman; R. Clement

    2004-01-01

    Surface exchange fluxes measured by eddy covariance tend to be underestimated as a result of limitations in sensor design, signal processing methods, and finite flux-averaging periods. But, careful system design, modern instrumentation, and appropriate data processing algorithms can minimize these losses, which, if not too large, can be estimated and corrected using...

  13. Benchmarking the mesoscale variability in global ocean eddy-permitting numerical systems

    Science.gov (United States)

    Cipollone, Andrea; Masina, Simona; Storto, Andrea; Iovino, Doroteaciro

    2017-10-01

    The role of data assimilation procedures on representing ocean mesoscale variability is assessed by applying eddy statistics to a state-of-the-art global ocean reanalysis (C-GLORS), a free global ocean simulation (performed with the NEMO system) and an observation-based dataset (ARMOR3D) used as an independent benchmark. Numerical results are computed on a 1/4 ∘ horizontal grid (ORCA025) and share the same resolution with ARMOR3D dataset. This "eddy-permitting" resolution is sufficient to allow ocean eddies to form. Further to assessing the eddy statistics from three different datasets, a global three-dimensional eddy detection system is implemented in order to bypass the need of regional-dependent definition of thresholds, typical of commonly adopted eddy detection algorithms. It thus provides full three-dimensional eddy statistics segmenting vertical profiles from local rotational velocities. This criterion is crucial for discerning real eddies from transient surface noise that inevitably affects any two-dimensional algorithm. Data assimilation enhances and corrects mesoscale variability on a wide range of features that cannot be well reproduced otherwise. The free simulation fairly reproduces eddies emerging from western boundary currents and deep baroclinic instabilities, while underestimates shallower vortexes that populate the full basin. The ocean reanalysis recovers most of the missing turbulence, shown by satellite products , that is not generated by the model itself and consistently projects surface variability deep into the water column. The comparison with the statistically reconstructed vertical profiles from ARMOR3D show that ocean data assimilation is able to embed variability into the model dynamics, constraining eddies with in situ and altimetry observation and generating them consistently with local environment.

  14. Subduction in an Eddy-Resolving State Estimate of the Northeast Atlantic Ocean

    Science.gov (United States)

    Gebbie, Geoffrey

    2004-01-01

    Are eddies an important contributor to subduction in the eastern subtropical gyre? Here, an adjoint model is used to combine a regional, eddy-resolving numerical model with observations to produce a state estimate of the ocean circulation. The estimate is a synthesis of a variety of in- situ observations from the Subduction Experiment, TOPEX/POSEIDON altimetry, and the MTI General Circulation Model. The adjoint method is successful because the Northeast Atlantic Ocean is only weakly nonlinear. The state estimate provides a physically-interpretable, eddy-resolving information source to diagnose subduction. Estimates of eddy subduction for the eastern subtropical gyre of the North Atlantic are larger than previously calculated from parameterizations in coarse-resolution models. Furthermore, eddy subduction rates have typical magnitudes of 15% of the total subduction rate. Eddies contribute as much as 1 Sverdrup to water-mass transformation, and hence subduction, in the North Equatorial Current and the Azores Current. The findings of this thesis imply that the inability to resolve or accurately parameterize eddy subduction in climate models would lead to an accumulation of error in the structure of the main thermocline, even in the relatively-quiescent eastern subtropical gyre.

  15. Design and application of a novel high precision and low cost electronic tachogenerator for sensor-based brushless direct current motor drivers.

    Science.gov (United States)

    Ozgenel, Mehmet Cihat; Bal, Gungor; Uygun, Durmus

    2017-03-01

    This study presents a precise speed control method for Brushless Direct Current (BLDC) Motors using an electronic tachogenerator (ETg) instead of an electro-mechanical tachogenerator. Most commonly used three-phase BLDC motors have three position sensors for rotor position data to provide commutation among stator windings. Aforementioned position sensors are usually Hall-effect sensors delivering binary-high and binary-low data as long as the motor rotates. These binary sets from three Hall-effect sensors can be used as an analogue rotor speed signal for closed loop applications. Each position sensor signal is apart from 120 electrical degrees. By using an electronic circuitry, a combination of position sensor signals is converted to the analogue signal providing an input to a PI speed controller. To implement this, a frequency to voltage converter has been used in this study. Then, the analogue speed signal has been evaluated as rotor speed data in comparison with the reference speed. So, an ETg system has been successfully achieved in place of an electro-mechanical tachogenerator for BLDC motor speed control. The proposed ETg has been tested under various speed conditions on an experimental setup. Employed tests and obtained results show that the proposed low-cost speed feedback sub-system can be effectively used in BLDC motor drive systems. Through the proved method and designed sub-system, a new motor controller chip with a speed feedback capability has been aimed.

  16. Cyclonic eddies in the eastern Gulf of Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Vukovich, F.M.; Maul, G.A.

    1985-01-01

    Cold-domed cyclonic eddies juxtaposed to the cyclonic shear side of the Gulf Loop Current are observed in simultaneously obtained hydrodgraphic, current meter mooring, and satellite infrared data. The cyclones are initially observed in the satellite data as cold perturbations on the northern extreme of the current and grow either into a cold tongue or a quasi-stable meander off the Dry Tortugas, Florida. Area shipboard surveys show closed isopleths of temperature and salinity, and surface geostropic current speeds relative to 1000 db are in excess of 100 cm s/sup -1/. The diameter of the cold domes varied from 80 to 120 km. Separation of large anticyclonic rings is always observed to be preceded by cylonic eddies in the transition zone between Campeche Bank and the West Florida Shelf, but only on the eastern side. Not every cyclonic eddy off Dry Tortugas is associated with the separation of an anticyclonic ring; some are eroded away by the Florida Current, but they have never been observed in 10 years of satellite data to advect eastward through the Straits of Florida.

  17. An intrathermocline eddy and a tropical cyclone in the Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Gordon, A.L.; Shroyer, E.; Murty, V.S.N.

    (ITE). An eddy tracking algorithm3 first detects the anticyclone near 13°N, 89°E on 24 August 2013, roughly 550 km from the location of the ship transect of the ITE. After the RV Revelle ITE observation the weak positive sea surface anomaly... from the surface intensified anticyclonic eddy on 27 November 2013. Intrathermocline Eddies An ITE, a class of subsurface vorticities4, have been detected in numerous regions including marginal seas, east- ern boundary currents, and within subtropical...

  18. The influence of Gulf Stream eddies and meanders on near-surface chlorophyll

    Science.gov (United States)

    Gaube, Peter; McGillicuddy, Dennis J.

    2017-04-01

    realistic surface stress that includes the influence of ocean surface currents. The second simulation neglects this process. The time evolution of CHL within eddies is very different in these two simulations. The model that includes eddy-induced Ekman pumping generates temporal trends in CHL that are similar to the observations.

  19. Events of equatorward translation of the Vitoria Eddy

    Science.gov (United States)

    Arruda, Wilton Z.; Campos, Edmo J. D.; Zharkov, Volodymyr; Soutelino, Rafael G.; da Silveira, Ilson C. A.

    2013-11-01

    The Vitoria Eddy (VE) is a cyclone in the Brazil Current (BC) formed immediately to the south of the Vitoria-Trindade Ridge. Using altimetric derived SSH and outputs of a regional ocean model, we show evidences that once the VE is shed from a BC meander, if it is not reabsorbed, it follows a northward path crossing the Vitoria-Trindade Ridge. In all observed events of equatorward translation, the VE interacts with the anticyclonic Abrolhos Eddy (AE) centered about 19°S-37°W. Depending on the strength of the AE, the VE can take one of two different paths: one orbiting the AE and the other tight to the bathymetric lines. During the entire translation, the AE is under the influence of the equatorward intermediate flow of the Intermediate Western Boundary Current/North Brazil Undercurrent system, a key factor for its equatorward translation.

  20. Local atmospheric response to warm mesoscale ocean eddies in the Kuroshio-Oyashio Confluence region.

    Science.gov (United States)

    Sugimoto, Shusaku; Aono, Kenji; Fukui, Shin

    2017-09-19

    In the extratropical regions, surface winds enhance upward heat release from the ocean to atmosphere, resulting in cold surface ocean: surface ocean temperature is negatively correlated with upward heat flux. However, in the western boundary currents and eddy-rich regions, the warmer surface waters compared to surrounding waters enhance upward heat release-a positive correlation between upward heat release and surface ocean temperature, implying that the ocean drives the atmosphere. The atmospheric response to warm mesoscale ocean eddies with a horizontal extent of a few hundred kilometers remains unclear because of a lack of observations. By conducting regional atmospheric model experiments, we show that, in the Kuroshio-Oyashio Confluence region, wintertime warm eddies heat the marine atmospheric boundary layer (MABL), and accelerate westerly winds in the near-surface atmosphere via the vertical mixing effect, leading to wind convergence around the eastern edge of eddies. The warm-eddy-induced convergence forms local ascending motion where convective precipitation is enhanced, providing diabatic heating to the atmosphere above MABL. Our results indicate that warm eddies affect not only near-surface atmosphere but also free atmosphere, and possibly synoptic atmospheric variability. A detailed understanding of warm eddy-atmosphere interaction is necessary to improve in weather and climate projections.

  1. Mesoscale eddies drive cross-shelf transport, particle and nutrient biogeochemistry, and the nutritional value of zooplankton

    Science.gov (United States)

    Waite, A.

    2016-02-01

    Mesoscale eddies drive a significant component of cross-shelf transport important in the ecology of coastal ecosystems. The Leeuwin Current off Western Australia has a high kinetic energy in southwest WA which peaks and becomes unstable in the austral autumn triggering the formation of eddies. We captured the dynamics of an evolving anticyclonic eddy in situ and we traced water masses as they were incorporated into the eddy. ADCP profiles confirmed periodic offshore movement of 2 Sv of shelf waters into the forming eddy from the adjacent shelf, carrying a load of shelf-sourced organic particles. Oxygen and nutrient profiles suggested rapid remineralization of nitrate mid-depth in the isolated water mass as it rotated, with a total drawdown of oxygen of 3.6 mol m-2 to 350 m ( 0.5 mol O2 m-2 d-1) on the timescale of 1 week. This implies that nitrate is acting primarily as a regenerated nutrient rather than as a source of new nitrogen. Zooplankton isotopic signatures indicated that warm-core eddies carried animals of poorer nutritional value than cold-core eddies, and this was reflected in the lipid content of rock lobster larvae isolated in the two eddy types. We present a conceptual model of the potential bottom-up control of zooplankton lipid stores by the mesoscale eddy field.

  2. Quantifying water flow within aquatic ecosystems using load cell sensors: a profile of currents experienced by coral reef organisms around Lizard Island, Great Barrier Reef, Australia.

    Science.gov (United States)

    Johansen, Jacob L

    2014-01-01

    Current velocity in aquatic environments has major implications for the diversity, abundance and ecology of aquatic organisms, but quantifying these currents has proven difficult. This study utilises a simple and inexpensive instrument (reef system around Lizard Island (Great Barrier Reef, Australia) at a spatial and temporal scale relevant to the ecology of individual benthos and fish. The instrument uses load-cell sensors to provide a correlation between sensor output and ambient current velocity of 99%. Each instrument is able to continuously record current velocities to >500 cms⁻¹ and wave frequency to >100 Hz over several weeks. Sensor data are registered and processed at 16 MHz and 10 bit resolution, with a measuring precision of 0.06±0.04%, and accuracy of 0.51±0.65% (mean ±S.D.). Each instrument is also pressure rated to 120 m and shear stresses ≤20 kNm⁻² allowing deployment in harsh environments. The instrument was deployed across 27 coral reef sites covering the crest (3 m), mid-slope (6 m) and deep-slope (9 m depth) of habitats directly exposed, oblique or sheltered from prevailing winds. Measurements demonstrate that currents over the reef slope and crest varies immensely depending on depth and exposure: currents differ up to 9-fold within habitats only separated by 3 m depth and 15-fold between exposed, oblique and sheltered habitats. Comparisons to ambient weather conditions reveal that currents around Lizard Island are largely wind driven. Zero to 22.5 knot winds correspond directly to currents of 0 to >82 cms⁻¹, while tidal currents rarely exceed 5.5 cms⁻¹. Rather, current velocity increases exponentially as a function of wave height (0 to 1.6 m) and frequency (0.54 to 0.20 Hz), emphasizing the enormous effect of wind and waves on organisms in these shallow coral reef habitats.

  3. Sensors for Entertainment.

    Science.gov (United States)

    Lamberti, Fabrizio; Sanna, Andrea; Rokne, Jon

    2016-07-15

    Sensors are becoming ubiquitous in all areas of science, technology, and society. In this Special Issue on "Sensors for Entertainment", developments in progress and the current state of application scenarios for sensors in the field of entertainment is explored.

  4. Surface integral formulation of Maxwell's equations for simulation of non-destructive testing by eddy currents. Preliminary study on the implementation of the fast multipole method; Formulation integrale surfacique des equations de Maxwell pour la simulation de controles non destructifs par courant de Foucault. Etude preliminaire a la mise en oeuvre de la methode multipole rapide.

    Energy Technology Data Exchange (ETDEWEB)

    Lim, T.

    2011-04-28

    To simulate numerically a non-destructive by eddy current testing (NDT-CF), the sensor response can be modeled through a semi-analytical approach by volume integral equations. Faster than the finite element method, this approach is however restricted to the study of plane or cylindrical parts (without taking into account the edge effects) because of the complexity of the expression of the dyadic Green function for more general configurations. However, there is an industrial demand to extend the capabilities of the CF model in complex configurations (deformed plates, edges effects...). We were thus brought to formulate the electromagnetic problem differently, by setting ourselves the goal of maintaining a semi-analytical approach. The surface integral equation (SIE) expresses the volume problem by an equivalent transmission one at the interfaces (2D) between homogeneous sub-domains. This problem is approached by a linear system (by the method of moments), whose number of unknowns is reduced due to the nature of the surfacic mesh. Therefore, this system can be solved by a direct solver for small configurations. That enabled us to treat several various positions of the sensor for only one inversion of the impedance matrix. The numerical results obtained using this formulation involve plates with consideration of edge effects such as edge and corner. They are consistent with results obtained by the finite element method. For larger configurations, we conducted a preliminary study for the adaptation of an acceleration method of the matrix vector product involved in an iterative solver (fast multipole method or FMM) to define the conditions under which the FMM calculation works correctly (accuracy, convergence...) in the NDT's domain. A special attention has been given to the choice of basis functions (which have to satisfy an Hdiv conforming property) and on the evaluation of near interactions (which are weakly singular). (author) [French] Pour simuler

  5. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    Melting ice is a tracer in this case. Shear cyclonic elements at the south- ern and eastern parts of the eddy periphery are well seen in both images. In a time of 3 days between the images the eddy shape and spatial ori- entation were not changed, however displacement of shear elements at its periphery in the direc-.

  6. Oceanic eddies in synthetic aperture radar images

    Indian Academy of Sciences (India)

    ... and in bays, spin-off eddies and mushroom-like structures (vortex dipoles) are given and discussed. It is shown that a common feature for most of the eddies detected in the SAR images is a broad spectrum of spatial scales, spiral shape and shear nature. It is concluded that the spaceborne SARs give valuable information ...

  7. An automatic method to analyze the Capacity-Voltage and Current-Voltage curves of a sensor

    CERN Document Server

    Matorras Cuevas, Pablo

    2017-01-01

    An automatic method to perform Capacity versus voltage analysis for all kind of silicon sensor is provided. It successfully calculates the depletion voltage to unirradiated and irradiated sensors, and with measurements with outliers or reaching breakdown. It is built using C++ and using ROOT trees with an analogous skeleton as TRICS, where the data as well as the results of the ts are saved, to make further analysis.

  8. Eddy Generation and Shedding in a Tidally Energetic Channel

    Science.gov (United States)

    McIlvenny, J.; Gillibrand, P. A.; Walters, R. A.

    2016-02-01

    The Pentland Firth in northern Scotland, and its subsidiary channel the Inner Sound, are currently under scrutiny as the first tidal energy array in the world is installed during 2016. The tidal flows in the channel and sound have been intensively observed and modelled in recent years, and the turbulent nature of the flow, with features of eddy generation and shedding, is becoming increasingly well known. Turbulence and eddies pose potential risks to the turbine infrastructure through enhanced stress on the blades, while understanding environmental effects of energy extraction also requires accurate simulation of the hydrodynamics of the flow. Here, we apply a mixed finite element/finite volume hydrodynamic model to the northern Scottish shelf, with a particular focus on flows through the Pentland Firth and the Inner Sound. We use an unstructured grid model, which allows the open boundaries to be far removed from the region of interest, while still allowing a grid spacing of 40m in the Inner Sound. The model employs semi-implicit techniques to solve the momentum and free surface equations, and semi-Lagrangian methods to solve the material derivative in the momentum equation, making it fast, robust and accurate and suitable for simulating flows in irregular coastal ocean environments. The model is well suited to address questions relating to tidal energy potential. We present numerical simulations of tidal currents in The Pentland Firth and Inner Sound. Observed velocities in the Inner Sound, measured by moored ADCP deployments, reach speeds of up to 5 m s-1 and the model successfully reproduces these strong currents. In the simulations, eddies are formed by interactions between the strong flow and the northern and southern headlands on the island of Stroma; some of these eddies are trapped and remain locked in position, whereas others are shed and transported away from the generation zone. We track the development and advection of eddies in relation to the site of

  9. Significance of cyclonic SubTropical Oceanic Rings of Magnitude (STORM) eddies for the carbon budget of the euphotic layer in the subtropical northeast Atlantic

    Science.gov (United States)

    MouriñO, Beatriz; FernáNdez, Emilio; Etienne, Helene; HernáNdez, Fabrice; Giraud, Sylvie

    2003-12-01

    The interannual and seasonal variability of cyclonic eddies budded from the Azores Current during the period 1993-1999 in the northeast subtropical Atlantic region (20°N-34°N; 19°W-35°W) was studied by using TOPEX/Poseidon and ERS-1/2 altimeter images, the operational ocean mesoscale forecasting system SOPRANE, and a mesoscale eddies automatic detection system. Seventeen cyclonic eddies were detected and monitored for time periods ranging from 50 to 360 days. They were characterized by mean westward velocity, amplitude, diameter, and eccentricity of about 2 km d-1, 8 cm, 187 km and 0.7, respectively. The generation of cyclonic eddies was subjected to an important interannual variability, especially in 1995 when the activity of cyclonic eddies in the northeast Atlantic was more intense and associated with parallel changes in the eddy energy of the Azores Current. Seventy-five percent of the mesoscale features were generated throughout the October-February period. Significant relationships were found between the seasonal NAO index and both the annual eddy kinetic and potential energy in the Azores Current region and also the total annual area occupied by STORM eddies, calculated with a 1-year phase lag. The outcome of this study was used to estimate the contribution of STORM eddies to the organic carbon deficit measured in the northeast subtropical Atlantic. On average, these eddies accounted for <1% of the net community production in the region.

  10. Detached eddy simulation and large eddy simulation models for the simulation of gas entrainment

    Energy Technology Data Exchange (ETDEWEB)

    Merzari, E.; Ninokata, H. [Research Laboratory for Nuclear Reactors, Tokyo Institute of Technology, Tokyo (Japan); Baglietto, E. [CD-adapco, New York, NY (United States)

    2007-07-01

    The eventual entrainment of gas bubbles in the reactor core of a Light Metal Fast Breeder Reactors (LMFBR) may cause an effective increase in reactivity as in the current state of the art since LMFBRs have usually a positive void coefficient. Since this may have a negative effect on safety and operation, the possibility of gas entrainment needs to be evaluated in the thermohydraulics design. Several studies on the gas entrainment in a LMFBR system have been conducted over the years. The most common situations that may lead to gas entrainment have been classified into vortex dimple, concave free surface and breaking wave. Among these, the vortex-induced gas entrainment phenomenon is considered in the present work, because more likely to be present in operating or accidental conditions. The focus is on the issue of turbulence modeling for the simulation of gas-driving vortexes, and in particular for the benchmark case of Moriya. We will propose two different approaches: a large eddy simulation and a detached eddy simulation. Results are in excellent agreement with the experiment for the radial velocity even if no surface model has been employed. (authors)

  11. A Galvanic Sensor for Monitoring the Corrosion Condition of the Concrete Reinforcing Steel: Relationship Between the Galvanic and the Corrosion Currents

    Directory of Open Access Journals (Sweden)

    Elsa Vaz Pereira

    2009-10-01

    Full Text Available This work reports a study carried out on the design and performance of galvanic and polarization resistance sensors to be embedded in concrete systems for permanent monitoring of the corrosion condition of reinforcing steel, aiming to establish a correlation between the galvanic currents, Igal, and the corrosion currents, Icorr, estimated from the polarization resistance, Rp. Sensors have been tested in saturated Ca(OH2 aqueous solutions, under a variety of conditions, simulating the most important parameters that can accelerate the corrosion of concrete reinforcing steel, such as carbonation, ingress of chloride ions, presence or absence of O2. For all the conditions, the influence of temperature (20 to 55 ºC has also been considered. From this study, it could be concluded that the galvanic currents are sensitive to the various parameters following a trend similar to that of the Rp values. A relationship between the galvanic and the corrosion current densities was obtained and the limiting values of the Igal, indicative of the state condition of the reinforcing steel for the designed sensor, were established.

  12. Interactions among DIV voltage-sensor movement, fast inactivation, and resurgent Na current induced by the NaVβ4 open-channel blocking peptide

    Science.gov (United States)

    Lewis, Amanda H.

    2013-01-01

    Resurgent Na current flows as voltage-gated Na channels recover through open states from block by an endogenous open-channel blocking protein, such as the NaVβ4 subunit. The open-channel blocker and fast-inactivation gate apparently compete directly, as slowing the onset of fast inactivation increases resurgent currents by favoring binding of the blocker. Here, we tested whether open-channel block is also sensitive to deployment of the DIV voltage sensor, which facilitates fast inactivation. We expressed NaV1.4 channels in HEK293t cells and assessed block by a free peptide replicating the cytoplasmic tail of NaVβ4 (the “β4 peptide”). Macroscopic fast inactivation was disrupted by mutations of DIS6 (L443C/A444W; “CW” channels), which reduce fast-inactivation gate binding, and/or by the site-3 toxin ATX-II, which interferes with DIV movement. In wild-type channels, the β4 peptide competed poorly with fast inactivation, but block was enhanced by ATX. With the CW mutation, large peptide-induced resurgent currents were present even without ATX, consistent with increased open-channel block upon depolarization and slower deactivation after blocker unbinding upon repolarization. The addition of ATX greatly increased transient current amplitudes and further enlarged resurgent currents, suggesting that pore access by the blocker is actually decreased by full deployment of the DIV voltage sensor. ATX accelerated recovery from block at hyperpolarized potentials, however, suggesting that the peptide unbinds more readily when DIV voltage-sensor deployment is disrupted. These results are consistent with two open states in Na channels, dependent on the DIV voltage-sensor position, which differ in affinity for the blocking protein. PMID:23940261

  13. Structural integrity inspection and monitoring by magneto-optic sensors

    Science.gov (United States)

    Dudziak, Martin J.

    1999-01-01

    Non-destructive testing for cracks, fissures, fatigue stress, and corrosion has been demonstrated using eddy- current induced magnetic fields measurable by sensors with Faraday magneto-optic properties. A novel class of such sensors has been developed, the MODE sensor, using Fe-Ga thin-films of the general form (R, Bi)3 (M, Fe)5-12 with R equals (Y, Lu, Tm, or other rare earth ions) and M equals Ga or Al. These films are characterized by very high uniaxial anisotropic field, Faraday rotation, absorption coefficient, and MO figure of merit, significantly improving sensitivity over previous thin film compositions. These properties enable their use in highly compact portable or remotely operated devices and requiring either no eddy current or else brief microbursts of electric current rather than lengthy application of steady current in order to induce magnetic fields within observed structures. A portable system for the testing of bridge structural components, fuel tanks, gas cylinders, and other metallic structures has been designed. This apparatus makes use of a compact portable computer into which video output from the MODE sensor unit received. Using a conventional software interface the operator is able to view the same structure in real time and to apply an array of image processing refinement techniques for improving the resolution of the image. Images may be stored as a constant video stream or as a set of individual snapshots. Additional features that enhance the utility of the system for mobile inspection tasks are discussed. These include the incorporation of a pattern recognition training algorithm and library for operator-enhanced identification of structural defects and condition assessments, as well as the broadcast of image and location data via wireless link to a central server for distribution to consulting engineers and for access of Microstation-type CAD files via a web browser interface.

  14. A review of wireless sensor technologies and applications in agriculture and food industry: state of the art and current trends.

    Science.gov (United States)

    Ruiz-Garcia, Luis; Lunadei, Loredana; Barreiro, Pilar; Robla, Jose Ignacio

    2009-01-01

    The aim of the present paper is to review the technical and scientific state of the art of wireless sensor technologies and standards for wireless communications in the Agri-Food sector. These technologies are very promising in several fields such as environmental monitoring, precision agriculture, cold chain control or traceability. The paper focuses on WSN (Wireless Sensor Networks) and RFID (Radio Frequency Identification), presenting the different systems available, recent developments and examples of applications, including ZigBee based WSN and passive, semi-passive and active RFID. Future trends of wireless communications in agriculture and food industry are also discussed.

  15. A Review of Wireless Sensor Technologies and Applications in Agriculture and Food Industry: State of the Art and Current Trends

    Science.gov (United States)

    Ruiz-Garcia, Luis; Lunadei, Loredana; Barreiro, Pilar; Robla, Jose Ignacio

    2009-01-01

    The aim of the present paper is to review the technical and scientific state of the art of wireless sensor technologies and standards for wireless communications in the Agri-Food sector. These technologies are very promising in several fields such as environmental monitoring, precision agriculture, cold chain control or traceability. The paper focuses on WSN (Wireless Sensor Networks) and RFID (Radio Frequency Identification), presenting the different systems available, recent developments and examples of applications, including ZigBee based WSN and passive, semi-passive and active RFID. Future trends of wireless communications in agriculture and food industry are also discussed. PMID:22408551

  16. A Review of Wireless Sensor Technologies and Applications in Agriculture and Food Industry: State of the Art and Current Trends

    Directory of Open Access Journals (Sweden)

    Ignacio Robla

    2009-06-01

    Full Text Available The aim of the present paper is to review the technical and scientific state of the art of wireless sensor technologies and standards for wireless communications in the Agri-Food sector. These technologies are very promising in several fields such as environmental monitoring, precision agriculture, cold chain control or traceability. The paper focuses on WSN (Wireless Sensor Networks and RFID (Radio Frequency Identification, presenting the different systems available, recent developments and examples of applications, including ZigBee based WSN and passive, semi-passive and active RFID. Future trends of wireless communications in agriculture and food industry are also discussed.

  17. Eddy-Resolving Simulation of the Atlantic Water Circulation in the Fram Strait With Focus on the Seasonal Cycle

    Science.gov (United States)

    Wekerle, Claudia; Wang, Qiang; von Appen, Wilken-Jon; Danilov, Sergey; Schourup-Kristensen, Vibe; Jung, Thomas

    2017-11-01

    Eddy driven recirculation of Atlantic Water (AW) in the Fram Strait modifies the amount of heat that reaches the Arctic Ocean, but is difficult to constrain in ocean models due to very small Rossby radius there. In this study, we explore the effect of resolved eddies on the AW circulation in a locally eddy-resolving simulation of the global Finite-Element-Sea ice-Ocean Model (FESOM) integrated for the years 2000-2009, by focusing on the seasonal cycle. An eddy-permitting simulation serves as a control run. Our results suggest that resolving local eddy dynamics is critical to realistically simulate ocean dynamics in the Fram Strait. Strong eddy activity simulated by the eddy-resolving model, with peak in winter and lower values in summer, is comparable in magnitude and seasonal cycle to observations from a long-term mooring array, whereas the eddy-permitting simulation underestimates the observed magnitude. Furthermore, a strong cold bias in the central Fram Strait present in the eddy-permitting simulation is reduced due to resolved eddy dynamics, and AW transport into the Arctic Ocean is increased with possible implications for the Arctic Ocean heat budget. Given the good agreement between the eddy-resolving model and measurements, it can help filling gaps that point-wise observations inevitably leave. For example, the path of the West Spitsbergen Current offshore branch, measured in the winter months by the mooring array, is shown to continue cyclonically around the Molloy Deep in the model, representing the major AW recirculation branch in this season.

  18. Removing Wave Artifacts from Eddy Correlation Data

    Science.gov (United States)

    Neumann, Andreas; Brand, Andreas

    2017-04-01

    The German Wadden Sea is an extensive system of back-barrier tidal basins along the margin of the southern North Sea. Due to their high productivity and the strong retention potential of labile organic carbon high mineralization rates are expected in this system. Since the sediment bed is sandy, the oxygen fluxes across the sediment-water interface (SWI) may be enhanced by strong tidal currents as well as by wind-induced surface waves. In order to measure oxygen fluxes in-situ without disturbance of the sediment, the Eddy Correlation method (ECM) was introduced to aquatic geoscience by Berg et al. (2003). The method is based on correlating turbulent fluctuations of oxygen concentration and vertical velocity measured at high frequency above the SWI. The method integrates over spatial heterogeneities and allows the observation of total benthic oxygen fluxes in complex systems where other methods like flux chamber deployments and oxygen profile measurements in the sediment fail. Therefore, the method should also reflect effects like the enhancement of oxygen fluxes by porewater advection driven by waves and currents over sandy sediments. Unfortunately the ECM suffers from wave contamination due to stirring sensitivity of the electrodes, spatial separation between the oxygen electrode and the location of velocity measurement as well as by a tilt of the measurement setup at the deployment side. In order to correct for this wave contamination we tested the method of spectral reconstruction initially introduced by Bricker and Monismith (2007) for the determination of Reynolds-stresses in wave-affected environments. In short, this method attempts to remove the wave signal from the Power spectral densities of oxygen concentration and vertical velocity fluctuations by cutting off the wave peak in these spectra. The wave contribution to the co-spectrum between both quantities is then reconstructed by assuming that the phasing in the wave band is dominated by the waves. Based

  19. Eddy dynamics in the Southern Ocean: How does the interaction of the Antarctic Circumpolar Current with sea-bed topography influence the surface mixed layer and hence the carbon-climate feedback processes?

    CSIR Research Space (South Africa)

    Kobo, N

    2012-10-01

    Full Text Available The Southern Ocean is an important sink for heat and CO2 and is one of the world’s most productive regions. The unique absence of blocking continents allows the Antarctic Circumpolar Current (ACC) to connect all ocean basins (Atlantic, Pacific...

  20. Optical Sensors for Planetary Radiant Energy (OSPREy): Calibration and Validation of Current and Next-Generation NASA Missions

    Science.gov (United States)

    Hooker, Stanford B.; Bernhard, Germar; Morrow, John H.; Booth, Charles R.; Comer, Thomas; Lind, Randall N.; Quang, Vi

    2012-01-01

    A principal objective of the Optical Sensors for Planetary Radiance Energy (OSPREy) activity is to establish an above-water radiometer system as a lower-cost alternative to existing in-water systems for the collection of ground-truth observations. The goal is to be able to make high-quality measurements satisfying the accuracy requirements for the vicarious calibration and algorithm validation of next-generation satellites that make ocean color and atmospheric measurements. This means the measurements will have a documented uncertainty satisfying the established performance metrics for producing climate-quality data records. The OSPREy approach is based on enhancing commercial-off-the-shelf fixed-wavelength and hyperspectral sensors to create hybridspectral instruments with an improved accuracy and spectral resolution, as well as a dynamic range permitting sea, Sun, sky, and Moon observations. Greater spectral diversity in the ultraviolet (UV) will be exploited to separate the living and nonliving components of marine ecosystems; UV bands will also be used to flag and improve atmospheric correction algorithms in the presence of absorbing aerosols. The short-wave infrared (SWIR) is expected to improve atmospheric correction, because the ocean is radiometrically blacker at these wavelengths. This report describes the development of the sensors, including unique capabilities like three-axis polarimetry; the documented uncertainty will be presented in a subsequent report.