A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university.

PubMed

Choi, Y H; Song, J B; Yang, D G; Kim, Y G; Hahn, S; Lee, H G

2016-10-01

This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university

NASA Astrophysics Data System (ADS)

Choi, Y. H.; Song, J. B.; Yang, D. G.; Kim, Y. G.; Hahn, S.; Lee, H. G.

2016-10-01

This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

Development of a REBCO HTS magnet for Maglev - repeated bending tests of HTS pancake coils -

NASA Astrophysics Data System (ADS)

Sugino, Motohikoa; Mizuno, Katsutoshi; Tanaka, Minoru; Ogata, Masafumi

2018-01-01

In the past study, two manufacturing methods were developed that can manufacture pancake coils by using REBCO coated conductors. It was confirmed that the conductors have no electric degradation that caused by the manufacturing method. The durability evaluation tests of the pancake coils were conducted as the final evaluation of the coil manufacturing method in this study. The repeated bending deformation was applied to manufactured pancake coils in the tests. As the results of these tests, it was confirmed that the pancake coils that were manufactured by two methods had the durability for the repeated bending deformation and the coils maintained the appropriate mechanical performance and electric performance. We adopted the fusion bonding method as the coil manufacturing method of the HTS magnet Furthermore, using the prototype pancake coil that was manufactured by the fusion bonding method as a test sample, the repeated bending test under the exited condition was conducted. Thus it was confirmed that the coil manufactured by the fusion bonding method has no degradation of the electricity performance and the mechanical properties even if the repeated bending deformation was applied under the exited condition.

High Radiation Environment Nuclear Fragment Separator Magnet

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

Kahn, Stephen; Gupta, Ramesh

2016-01-31

Superconducting coils wound with HTS conductor can be used in magnets located in a high radiation environment. NbTi and Nb 3Sn superconductors must operate at 4.5 K or below where removal of heat is less efficient. The HTS conductor can carry significant current at higher temperatures where the Carnot efficiency is significantly more favorable and where the coolant heat capacity is much larger. Using the HTS conductor the magnet can be operated at 40 K. This project examines the use of HTS conductor for the Michigan State University Facility For Rare Isotope Beams (FRIB) fragment separator dipole magnet which bendsmore » the beam by 30° and is located in a high radiation region that will not be easily accessible. Two of these magnets are needed to select the chosen isotope. There are a number of technical challenges to be addressed in the design of this magnet. The separator dipole is 2 m long and subtends a large angle. The magnet should keep a constant transverse field profile along its beam reference path. Winding coils with a curved inner segment is difficult as the conductor will tend to unwind during the process. In the Phase I project two approaches to winding the conductor were examined. The first was to wind the coils with curved sections on the inner and outer segments with the inner segment wound with negative curvature. The alternate approach was to use a straight segment on the inner segment to avoid negative curvature. In Phase I coils with a limited number of turns were successfully wound and tested at 77 K for both coil configurations. The Phase II program concentrated on the design, coil winding procedures, structural analysis, prototyping and testing of an HTS curved dipole coil at 40 K with a heat load representative of the radiation environment. One of the key criteria of the design of this magnet is to avoid the use of organic materials that would degrade rapidly in radiation. The Lorentz forces expected from the coils interacting with the magnetic field are large and in order minimize the deformation of the coils, mechanical support must be provided. Since the support structure cannot be made of organic materials with minimal thermal conductivity, an optimization was explored comparing the amount of coil deformation that can be tolerated and the amount of heat leakage that can be endured. A test coil containing 500 m of HTS was constructed to be tested at the 40 K operating temperature. The anticipated heat load was simulated with heater strips to demonstrate that the heat could be removed and that the coil can operate in a stable state. The FRIB project has decided that using HTS coils for this magnet was too risky considering their time and funding constraints and has opted for a more conservative approach with conventional coils. As an outcome of this STTR project, it is likely that HTS coils operating at higher temperatures will have beneficial applications for future accelerator projects.« less

Development and positioning reliability of a TMS coil holder for headache research.

PubMed

Chronicle, Edward P; Pearson, A Jane; Matthews, Cheryl

2005-01-01

Accurate and reproducible coil positioning is important for headache research using transcranial magnetic stimulation protocols. We aimed to design a transcranial magnetic stimulation coil holder and demonstrate reliability of test-retest coil positioning. A coil holder was developed and manufactured according to three principles of stability, durability, and three-dimensional positional accuracy. Reliability of coil positioning was assessed by stimulating over the motor cortex of four neurologically normal subjects and recording finger muscle responses, both at a test phase and a retest phase several hours later. In all four subjects, repositioning of the transcranial magnetic stimulation coil solely on the basis of coil holder coordinates was accurate to within 2 mm. The coil holder demonstrated good test-retest reliability of coil positioning, and is thus a promising tool for transcranial magnetic stimulation-based headache research, particularly studies of prophylactic drug effect where several laboratory visits with identical coil positioning are necessary.

Progress in the Long $${\\rm Nb}_{3}{\\rm Sn}$$ Quadrupole R&D by LARP

DOE PAGES

Ambrosio, G.; Andreev, N.; Anerella, M.; ...

2011-11-14

After the successful test of the first long Nb 3Sn quadrupole (LQS01) the US LHC Accelerator Research Program (LARP, a collaboration of BNL, FNAL, LBNL and SLAC) is assessing training memory, reproducibility, and other accelerator quality features of long Nb 3Sn quadrupole magnets. LQS01b (a reassembly of LQS01 with more uniform and higher pre-stress) was subjected to a full thermal cycle and reached the previous plateau of 222 T/m at 4.5 K in two quenches. A new set of four coils, made of the same type of conductor used in LQS01 (RRP 54/61 by Oxford Superconducting Technology), was assembled inmore » the LQS01 structure and tested at 4.5 K and lower temperatures. The new magnet (LQS02) reached the target gradient (200 T/m) only at 2.6 K and lower temperatures, at intermediate ramp rates. The preliminary test analysis, here reported, showed a higher instability in the limiting coil than in the other coils of LQS01 and LQS02.« less

Field Quality and Fabrication Analysis of HQ02 Reconstructed Nb3Sn Coil Cross Sections

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

Holik, Eddie Frank; Ambrosio, Giorgio; Carbonara, Andrea

2017-01-23

The US LHC Accelerator Research Program (LARP) quadrupole HQ02 was designed and fully tested as part of the low-beta quad development for Hi-Lumi LHC. HQ02’s design is well documented with full fabrication accounting along with full field analysis at low and high current. With this history, HQ02 is an excellent test bed for developing a methodology for measuring turn locations from magnet cross sections and comparing with CAD models and measured field. All 4 coils of HQ02 were cut in identical locations along the magnetic length corresponding to magnetic field measurement and coil metrology. A real-time camera and coordinate measuringmore » equipment was used to plot turn corners. Measurements include systematic and random displacements of winding blocks and individual turns along the magnetic length. The range of cable shifts and the field harmonic range along the length are in agreement, although correlating turn locations and measured harmonics in each cross section is challenging.« less

Analysis of field errors for LARP Nb 3Sn HQ03 quadrupole magnet

DOE PAGES

Wang, Xiaorong; Ambrosio, Giorgio; Chlachidze, Guram; ...

2016-12-01

The U.S. LHC Accelerator Research Program, in close collaboration with CERN, has developed three generations of high-gradient quadrupole (HQ) Nb 3Sn model magnets, to support the development of the 150 mm aperture Nb 3Sn quadrupole magnets for the High-Luminosity LHC. The latest generation, HQ03, featured coils with better uniformity of coil dimensions and properties than the earlier generations. We tested the HQ03 magnet at FNAL, including the field quality study. The profiles of low-order harmonics along the magnet aperture observed at 15 kA, 1.9 K can be traced back to the assembled coil pack before the magnet assembly. Based onmore » the measured harmonics in the magnet center region, the coil block positioning tolerance was analyzed and compared with earlier HQ01 and HQ02 magnets to correlate with coil and magnet fabrication. Our study the capability of correcting the low-order non-allowed field errors, magnetic shims were installed in HQ03. Furthermore, the expected shim contribution agreed well with the calculation. For the persistent-current effect, the measured a4 can be related to 4% higher in the strand magnetization of one coil with respect to the other three coils. Lastly, we compare the field errors due to the inter-strand coupling currents between HQ03 and HQ02.« less

A magnetic shield/dual purpose mission

NASA Technical Reports Server (NTRS)

Watkins, Seth; Albertelli, Jamil; Copeland, R. Braden; Correll, Eric; Dales, Chris; Davis, Dana; Davis, Nechole; Duck, Rob; Feaster, Sandi; Grant, Patrick

1994-01-01

The objective of this work is to design, build, and fly a dual-purpose payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field to protect manned spacecraft against particle radiation. An additional mission objective is to study the effect of this moving field on upper atmosphere plasmas. Both mission objectives appear to be capable of being tested using the same superconducting coil. The potential benefits of this magnetic shield concept apply directly to both earth-orbital and interplanetary missions. This payload would be a first step in assessing the true potential of large volume magnetic fields in the U.S. space program. Either converted launch systems or piggyback payload opportunities may be appropriate for this mission. The use of superconducting coils for magnetic shielding against solar flare radiation during manned interplanetary missions has long been contemplated and was considered in detail in the years preceding the Apollo mission. With the advent of new superconductors, it has now become realistic to reconsider this concept for a Mars mission. Even in near-earth orbits, large volume magnetic fields produced using conventional metallic superconductors allow novel plasma physics experiments to be contemplated. Both deployed field-coil and non-deployed field-coil shielding arrangements have been investigated, with the latter being most suitable for an initial test payload in a polar orbit.

Construction and Test Results of Coils 2 and 3 of a 3-Nested-Coil 800-MHz REBCO Insert for the MIT 1.3-GHz LTS/HTS NMR Magnet.

PubMed

Park, Dongkeun; Bascuñán, Juan; Michael, Philip C; Lee, Jiho; Hahn, Seungyong; Iwasa, Yukikazu

2018-04-01

We present construction and test results of Coils 2 and 3 of a 3-coil 800-MHz REBCO insert (H800) for the MIT 1.3 GHz LTS/HTS NMR magnet currently under construction. Each of three H800 coils (Coils 1-3) is a stack of no-insulation REBCO double pancakes (DPs). The innermost 8.67-T Coil 1 (26 DPs) was completed in 2016; the middle 5.64-T Coil 2 (32 DPs) has been wound, assembled, and tested; and for the outermost 4.44-T Coil 3, its 38 DPs have been wound and preliminary tests were performed to characterize each DP at 77 K. Included for Coil 2 are: 1) 77-K data of critical current, index, and turn-to-turn characteristic resistivity of each DP; 2) stacking order of the 32 DPs optimized to maximize the Coil 2 current margin and minimize its Joule dissipation in the pancake-to-pancake joints; 3) procedure to experimentally determine and apply a room-temperature preload to the DP stack; 4) 77-K and 4.2-K test results after each of 64 pancakes was over-banded with 75-μm-thick stainless steel tape for a radial thickness of 5 mm. Presented for each DP in Coil 3 are 77-K dada of critical current, index, and turn-to-turn characteristic resistivity.

Frequency Characteristics of the MAGLEV Double-layered Propulsion Coil

NASA Astrophysics Data System (ADS)

Ema, Satoshi

The MAGLEV (magnetically levitated vehicle) is now well along in development testing at Yamanashi Test Line. The MAGLEV power source needs to supply a variable voltage and variable frequency to propulsion coils, which installed on outdoor guideway. The output voltage of the electric power converter contains many higher harmonics, which causes many troubles such as inductive interference. Accordingly, it is necessary to clarify the frequency characteristics of the propulsion coils and the power feeding circuit. In view of this situation, experiments and the theoretical analysis concerning the frequency characteristics of the propulsion coils with single-layer arrangement and the power feeding circuit at Miyazaki Test Line had been performed by the author. But the arrangement of the propulsion coils had been changed in Yamanashi Test Line from the single-layered coils to the double-layered coils for the stability of the super-conducting magnet on board. Thus, experiments and investigations concerning the frequency characteristics(resonance characteristics)of the propulsion coils with double-layer arrangement at Yamanashi Test Line have been performed but a theoretical analysis had not been done enough. A theoretical analysis was therefore done in this paper by applying the inverted L equivalent circuit with mutual inductance and capacitance to the propulsion coil, from which the positive and zero phase characteristics of the double-layered propulsion coils were analyzed.

Testing of machine wound second generation HTS tape Vacuum Pressure Impregnated coils

NASA Astrophysics Data System (ADS)

Swaffield, D.; Lewis, C.; Eugene, J.; Ingles, M.; Peach, D.

2014-05-01

Delamination of second generation (2G) High Temperature Superconducting (HTS) tapes has previously been reported when using resin based insulation systems for wound coils. One proposed root cause is the differential thermal contraction between the coil former and the resin encapsulated coil turns resulting in the tape c-axis tensile stress being exceeded. Importantly, delamination results in unacceptable degradation of the superconductor critical current level. To mitigate the delamination risk and prove winding, jointing and Vacuum Pressure Impregnation (VPI) processes in the production of coils for superconducting rotating machines at GE Power Conversion two scaled trial coils have been wound and extensively tested. The coils are wound from 12mm wide 2G HTS tape supplied by AMSC onto stainless steel 'racetrack' coil formers. The coils are wound in two layers which include both in-line and layer-layer joints subject to in-process test. The resin insulation system chosen is VPI and oven cured. Tests included; insulation resistance, repeat quench and recovery of the superconductor, heat runs and measurement of n-value, before and after multiple thermal cycling between ambient and 35 Kelvin. No degradation of coil performance is evidenced.

Magnetic Test Performance Capabilities at the Goddard Space Flight Center as Applied to the Global Geospace Science Initiative

NASA Technical Reports Server (NTRS)

Mitchell, Darryl R.

1997-01-01

Goddard Space Flight Center's (GSFC) Spacecraft Magnetic Test Facility (SMTF) is a historic test facility that has set the standard for all subsequent magnetic test facilities. The SMTF was constructed in the early 1960's for the purpose of simulating geomagnetic and interplanetary magnetic fields. Additionally, the facility provides the capability for measuring spacecraft generated magnetic fields as well as calibrating magnetic attitude control systems and science magnetometers. The SMTF was designed for large, spacecraft level tests and is currently the second largest spherical coil system in the world. The SMTF is a three-axis Braunbek system composed of four coils on each of three orthogonal axes. The largest coils are 12.7 meters (41.6 feet) in diameter. The three-axis Braunbek configuration provides a highly uniform cancellation of the geomagnetic field over the central 1.8 meter (6 foot) diameter primary test volume. Cancellation of the local geomagnetic field is to within +/-0.2 nanotesla with a uniformity of up to 0.001% within the 1.8 meter (6 foot) diameter primary test volume. Artificial magnetic field vectors from 0-60,000 nanotesla can be generated along any axis with a 0.1 nanotesla resolution. Oscillating or rotating field vectors can also be produced about any axis with a frequency of up to 100 radians/second. Since becoming fully operational in July of 1967, the SMTF has been the site of numerous spacecraft magnetics tests. Spacecraft tested at the SMTF include: the Solar Maximum Mission (SMM), Magsat, LANDSAT-D, the Fast Aurora] Snapshot (FAST) Explorer and the Sub-millimeter-Wave-Astronomy Satellite (SWAS) among others. This paper describes the methodology and sequencing used for the Global Geospace Science (GGS) initiative magnetic testing program in the Goddard Space Flight Center's SMTF. The GGS initiative provides an exemplary model of a strict and comprehensive magnetic control program.

A new method of radio frequency links by coplanar coils for implantable medical devices.

PubMed

Xue, L; Hao, H W; Li, L; Ma, B Z

2005-01-01

A new method based on coplanar coils for the design of radio frequency links has been developed, to realize the communication between the programming wand and the implantable medical devices with shielding container simply and reliably. With the analysis of electronic and magnetic field theory, the communication model has been established and simulated, and the circuit has been designed and tested. The experimental results are consistent with the simulation fairly well. The voltage transfer ratio of the typical circuit with present parameters can reach as high as 0.02, which can fulfill the requirements of communication.

Coil Migration, Malposition, Stretching and Retrieval

PubMed Central

Abe, T.; Hirohata, M.; Tanaka, N.; Uchiyama, Y.; Morimitsu, H.; Kojima, K.; Hayabuchi, N.

2000-01-01

Summary In this educational program for complicated coil placements, we report several cases of coil malposition, migration, and retrieval. We emphasize that a decrease in the expected one-to-one motion of the coil is the earliest sign of a possible imminent complication, and the over the core wire technique with a fixed-loop snare (Gooseneck microsnare) is a very effective potential solution for elongated coil retrieval. PMID:20667237

Development of variable-width ribbon heating elements for liquid-metal and gas-cooled fast breeder reactor fuel-pin simulators

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

McCulloch, R.W.; Post, D.W.; Lovell, R.T.

1981-04-01

Variable-width ribbon heating elements that provide a chopped-cosine variable heat flux profile have been fabricated for fuel pin simulators used in test loops by the Breeder Reactor Program Thermal-Hydraulic Out-of-Reactor Safety test facility and the Gas-Cooled Fast Breeder Reactor-Core Flow Test Loop. Thermal, mechanical, and electrical design considerations are used to derive an analytical expression that precisely describes ribbon contour in terms of the major fabrication parameters. These parameters are used to generate numerical control tapes that control ribbon cutting and winding machines. Infrared scanning techniques are developed to determine the optimum transient thermal profile of the coils and relatemore » this profile to that generated by the coils in completed fuel pin simulators.« less

Using finite element modelling and experimental methods to investigate planar coil sensor topologies for inductive measurement of displacement

NASA Astrophysics Data System (ADS)

Moreton, Gregory; Meydan, Turgut; Williams, Paul

2018-04-01

The usage of planar sensors is widespread due to their non-contact nature and small size profiles, however only a few basic design types are generally considered. In order to develop planar coil designs we have performed extensive finite element modelling (FEM) and experimentation to understand the performance of different planar sensor topologies when used in inductive sensing. We have applied this approach to develop a novel displacement sensor. Models of different topologies with varying pitch values have been analysed using the ANSYS Maxwell FEM package, furthermore the models incorporated a movable soft magnetic amorphous ribbon element. The different models used in the FEM were then constructed and experimentally tested with topologies that included mesh, meander, square coil, and circular coil configurations. The sensors were used to detect the displacement of the amorphous ribbon. A LabView program controlled both the displacement stage and the impedance analyser, the latter capturing the varying inductance values with ribbon displacement. There was good correlation between the FEM models and the experimental data confirming that the methodology described here offers an effective way for developing planar coil based sensors with improved performance.

Preliminary design of a superconducting coil array for NASA prototype magnetic balance. M.S. Thesis

NASA Technical Reports Server (NTRS)

Alishahi, M. M.

1980-01-01

Using a computer program a partly optimized configuration for a supeconducting version of side and lift coil system of NASA-MIT prototype is presented. Cable size for the mentioned coils and also for superconducting drag and magnetizing coils regarding the overall computed field was determined.

Thermal-hydraulic analysis of the coil test facility for CFETR.

PubMed

Ren, Yong; Liu, Xiaogang; Li, Junjun; Wang, Zhaoliang; Qiu, Lilong; Du, Shijun; Li, Guoqiang; Gao, Xiang

2016-01-01

Performance test of the China Fusion Engineering Test Reactor (CFETR) central solenoid (CS) and toroidal field (TF) insert coils is of great importance to evaluate the CFETR magnet performance in relevant operation conditions. The superconducting magnet of the coil test facility for CFETR is being designed with the aim of providing a background magnetic field to test the CFETR CS insert and TF insert coils. The superconducting magnet consists of the inner module with Nb 3 Sn coil and the outer module with NbTi coil. The superconducting magnet is designed to have a maximum magnetic field of 12.59 T and a stored energy of 436.6 MJ. An active quench protection circuit and the positive temperature coefficient dump resistor were adopted to transfer the stored magnetic energy. The temperature margin behavior of the test facility for CFETR satisfies the design criteria. The quench analysis of the test facility shows that the cable temperature and the helium pressure inside the jacket are within the design criteria.

Approach for removing ghost-images in remote field eddy current testing of ferromagnetic pipes

NASA Astrophysics Data System (ADS)

Luo, Q. W.; Shi, Y. B.; Wang, Z. G.; Zhang, W.; Zhang, Y.

2016-10-01

In the non-destructive testing of ferromagnetic pipes based on remote field eddy currents, an array of sensing coils is often used to detect local defects. While testing, the image that is obtained by sensing coils exhibits a ghost-image, which originates from both the transmitter and sensing coils passing over the same defects in pipes. Ghost-images are caused by transmitters and lead to undesirable assessments of defects. In order to remove ghost-images, two pickup coils are coaxially set to each other in remote field. Due to the time delay between differential signals tested by the two pickup coils, a Wiener deconvolution filter is used to identify the artificial peaks that lead to ghost-images. Because the sensing coils and two pickup coils all receive the same signal from one transmitter, they all contain the same artificial peaks. By subtracting the artificial peak values obtained by the two pickup coils from the imaging data, the ghost-image caused by the transmitter is eliminated. Finally, a relatively highly accurate image of local defects is obtained by these sensing coils. With proposed method, there is no need to subtract the average value of the sensing coils, and it is sensitive to ringed defects.

Approach for removing ghost-images in remote field eddy current testing of ferromagnetic pipes.

PubMed

Luo, Q W; Shi, Y B; Wang, Z G; Zhang, W; Zhang, Y

2016-10-01

In the non-destructive testing of ferromagnetic pipes based on remote field eddy currents, an array of sensing coils is often used to detect local defects. While testing, the image that is obtained by sensing coils exhibits a ghost-image, which originates from both the transmitter and sensing coils passing over the same defects in pipes. Ghost-images are caused by transmitters and lead to undesirable assessments of defects. In order to remove ghost-images, two pickup coils are coaxially set to each other in remote field. Due to the time delay between differential signals tested by the two pickup coils, a Wiener deconvolution filter is used to identify the artificial peaks that lead to ghost-images. Because the sensing coils and two pickup coils all receive the same signal from one transmitter, they all contain the same artificial peaks. By subtracting the artificial peak values obtained by the two pickup coils from the imaging data, the ghost-image caused by the transmitter is eliminated. Finally, a relatively highly accurate image of local defects is obtained by these sensing coils. With proposed method, there is no need to subtract the average value of the sensing coils, and it is sensitive to ringed defects.

Change in the coil distribution of electrodynamic suspension system

NASA Technical Reports Server (NTRS)

Tanaka, Hisashi

1992-01-01

At the Miyazaki Maglev Test Center, the initial test runs were completed using a system design that required the superconducting coils to be parallel with the ground levitation coils. Recently, the coil distribution was changed to a system such that the two types of coils were perpendicular to each other. Further system changes will lead to the construction of a side wall levitation system. It is hoped that the development will culminate in a system whereby a superconducting coil will maintain all the functions: levitation, propulsion, and guidance.

Characterization of the ITER CS conductor and projection to the ITER CS performance

DOE PAGES

Martovetsky, N.; Isono, T.; Bessette, D.; ...

2017-06-20

The ITER Central Solenoid (CS) is one of the critical elements of the machine. The CS conductor went through an intense optimization and qualification program, which included characterization of the strands, a conductor straight short sample testing in the SULTAN facility at the Swiss Plasma Center (SPC), Villigen, Switzerland, and a single-layer CS Insert coil recently tested in the Central Solenoid Model Coil (CSMC) facility in QST-Naka, Japan. In this paper, we obtained valuable data in a wide range of the parameters (current, magnetic field, temperature, and strain), which allowed a credible characterization of the CS conductor in different conditions.more » Finally, using this characterization, we will make a projection to the performance of the CS in the ITER reference scenario.« less

BaBar superconducting coil: design, construction and test

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

Bell, R A; Berndt, M; Burgess, W

2001-01-26

The BABAR Detector, located in the PEP-II B-Factory at the Stanford Linear Accelerator Center, includes a large 1.5 Tesla superconducting solenoid, 2.8 m bore and length 3.7 m. The two layer solenoid is wound with an aluminum stabilized conductor which is graded axially to produce a {+-} 3% field uniformity in the tracking region. This paper summarizes the 3 year design, fabrication and testing program of the superconducting solenoid. The work was carried out by an international collaboration between INFN, LLNL and SLAC. The coil was constructed by Ansaldo Energia. Critical current measurements of the superconducting strand, cable and conductor,more » cool-down, operation with the thermo-siphon cooling, fast and slow discharges, and magnetic forces are discussed in detail.« less

Characterization of the ITER CS conductor and projection to the ITER CS performance

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

Martovetsky, N.; Isono, T.; Bessette, D.

The ITER Central Solenoid (CS) is one of the critical elements of the machine. The CS conductor went through an intense optimization and qualification program, which included characterization of the strands, a conductor straight short sample testing in the SULTAN facility at the Swiss Plasma Center (SPC), Villigen, Switzerland, and a single-layer CS Insert coil recently tested in the Central Solenoid Model Coil (CSMC) facility in QST-Naka, Japan. In this paper, we obtained valuable data in a wide range of the parameters (current, magnetic field, temperature, and strain), which allowed a credible characterization of the CS conductor in different conditions.more » Finally, using this characterization, we will make a projection to the performance of the CS in the ITER reference scenario.« less

Test results of the LARP Nb$$_3$$Sn quadrupole HQ03a

DOE PAGES

DiMarco, J.; G. Ambrosio; Chlachidze, G.; ...

2016-03-09

The US LHC Accelerator Research Program (LARP) has been developingmore » $$Nb_3Sn$$ quadrupoles of progressively increasing performance for the high luminosity upgrade of the Large Hadron Collider. The 120 mm aperture High-field Quadrupole (HQ) models are the last step in the R&D phase supporting the development of the new IR Quadrupoles (MQXF). Three series of HQ coils were fabricated and assembled in a shell-based support structure, progressively optimizing the design and fabrication process. The final set of coils consistently applied the optimized design solutions, and was assembled in the HQ03a model. Furthermore, this paper reports a summary of the HQ03a test results, including training, mechanical performance, field quality and quench studies.« less

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

Neilson, G. H.; Heitzenroeder, P.; Lyon, J.

Stellarators use 3D plasma and magnetic field shaping to produce a steady-state disruption-free magnetic confinement configuration. Compact stellarators have additional attractive properties — quasi-symmetric magnetic fields and low aspect ratio. The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in partnership with the Oak Ridge National Laboratory (ORNL) to test the physics of a high-beta compact stellarator with a lowripple, tokamak-like magnetic configuration. The engineering challenges of NCSX stem from its complex geometry requirements. These issues are addressed in the construction project through manufacturing R&D and system engineering. As a result, the fabricationmore » of the coil winding forms and vacuum vessel are proceeding in industry without significant technical issues, and preparations for winding the coils at PPPL are in place. Design integration, analysis, and dimensional control are functions provided by system engineering to ensure that the finished product will satisfy the physics requirements, especially accurate realization of the specified coil geometries. After completion of construction in 2009, a research program to test the expected physics benefits will start.« less

Inductive Pulsed Plasma Thruster Development and Testing at NASA-MSFC

NASA Technical Reports Server (NTRS)

Polzin, Kurt A.

2013-01-01

THE inductive pulsed plasma thruster (IPPT) is an electrodeless space propulsion device where a capacitor is charged to an initial voltage and then discharged producing a high current pulse through a coil. The field produced by this pulse ionizes propellant, inductively driving current in a plasma located near the face of the coil. Once the plasma is formed it can be accelerated and expelled at a high exhaust velocity by the electromagnetic Lorentz body force arising from the interaction of the induced plasma current and the magnetic field produced by the current in the coil. In the present work, we present a summary of the IPPT research and development conducted at NASA's Marshall Space Flight Center (MSFC). As a higher-power, still relatively low readiness level system, there are many issues associated with the eventual deployment and use of the IPPT as a primary propulsion system on spacecraft that remain to be addressed. The present program aimed to fabricate and test hardware to explore how these issues could be addressed. The following specific areas were addressed within the program and will be discussed within this paper. a) Conical theta-pinch IPPT geometry thruster configuration. b) Repetition-rate multi-kW thruster pulsing. c) Long-lifetime pulsed gas valve. d) Fast pulsed gas valve driver and controller. e) High-voltage, repetitive capacitor charging power processing unit. During the course of testing, a number of specific tests were conducted, including several that, to our knowledge, have either never been previously conducted (such as multi-KW repetition-rate operation) or have not been performed since the early 1990s (direct IPPT thrust measurements).2 Conical theta-pinch IPPT thrust stand measurements are presented in Fig. 1 while various time-integrated and time

An HMM model for coiled-coil domains and a comparison with PSSM-based predictions.

PubMed

Delorenzi, Mauro; Speed, Terry

2002-04-01

Large-scale sequence data require methods for the automated annotation of protein domains. Many of the predictive methods are based either on a Position Specific Scoring Matrix (PSSM) of fixed length or on a window-less Hidden Markov Model (HMM). The performance of the two approaches is tested for Coiled-Coil Domains (CCDs). The prediction of CCDs is used frequently, and its optimization seems worthwhile. We have conceived MARCOIL, an HMM for the recognition of proteins with a CCD on a genomic scale. A cross-validated study suggests that MARCOIL improves predictions compared to the traditional PSSM algorithm, especially for some protein families and for short CCDs. The study was designed to reveal differences inherent in the two methods. Potential confounding factors such as differences in the dimension of parameter space and in the parameter values were avoided by using the same amino acid propensities and by keeping the transition probabilities of the HMM constant during cross-validation. The prediction program and the databases are available at http://www.wehi.edu.au/bioweb/Mauro/Marcoil

Fabrication and Analysis of 150-mm-Aperture Nb 3Sn MQXF Coils

DOE PAGES

Holik, E. F.; Ambrosio, G.; Anerella, M.; ...

2016-01-12

The U.S. LHC Accelerator Research Program (LARP) and CERN are combining efforts for the HiLumi-LHC upgrade to design and fabricate 150-mm-aperture, interaction region quadrupoles with a nominal gradient of 130 T/m using Nb 3Sn. To successfully produce the necessary long MQXF triplets, the HiLumi-LHC collaboration is systematically reducing risk and design modification by heavily relying upon the experience gained from the successful 120-mm-aperture LARP HQ program. First generation MQXF short (MQXFS) coils were predominately a scaling up of the HQ quadrupole design allowing comparable cable expansion during Nb 3Sn formation heat treatment and increased insulation fraction for electrical robustness. Amore » total of 13 first generation MQXFS coils were fabricated between LARP and CERN. Systematic differences in coil size, coil alignment symmetry, and coil length contraction during heat treatment are observed and likely due to slight variances in tooling and insulation/cable systems. Analysis of coil cross sections indicate that field-shaping wedges and adjacent coil turns are systematically displaced from the nominal location and the cable is expanding less than nominally designed. Lastly, a second generation MQXF coil design seeks to correct the expansion and displacement discrepancies by increasing insulation and adding adjustable shims at the coil pole and midplanes to correct allowed magnetic field harmonics.« less

High-Resolution and Frequency, Printed Miniature Magnetic Probes

NASA Astrophysics Data System (ADS)

Prager, James; Ziemba, Timothy; Miller, Kenneth; Picard, Julian

2013-10-01

Eagle Harbor Technologies, Inc. (EHT) is developing a technique to significantly reduce the cost and development time of producing magnetic field diagnostics. EHT is designing probes that can be printed on flexible PCBs thereby allowing for extremely small coils to be produced while essentially eliminating the time to wind the coils. The coil size can be extremely small when coupled with the EHT Hybrid Integrator, which is capable of high bandwidth measurements over short and long pulse durations. This integrator is currently being commercialized with the support of a DOE SBIR. Additionally, the flexible PCBs allow probes to be attached to complex surface and/or probes that have a complex 3D structure to be designed and fabricated. During the Phase I, EHT will design and construct magnetic field probes on flexible PCBs, which will be tested at the University of Washington's HIT-SI experiment and in EHT's material science plasma reactor. Funding provided by DOE SBIR/STTR Program.

Coil End Parts Development Using BEND and Design for MQXF by LARP

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

Yu, Miao; Ambrosio, G.; Bermudez, S. Izquierdo

2016-09-06

End parts are critical components for saddle-shaped coils. They have a structural function where the cables are deformed in order to cross over the magnet aperture. Based on the previous design of the US LARP program for 90 mm aperture quadrupoles (TQ/LQ) and 120 mm aperture quadrupoles (HQ/LHQ) using BEND, the coil ends of the low-β quadruples (MQXF) for the HiLumi LHC upgrade were developed. This paper shows the design of the MQXF coil ends, the analysis of the coil ends during the coil fabrication, the autopsy analysis of the coil ends and the feedback to BEND parameters.

Construction and Test Results of Coil 2 of a Three-Coil 800-MHz REBCO Insert for the 1.3-GHz High-Resolution NMR Magnet.

PubMed

Bascuñán, Juan; Michael, Philip; Hahn, Seungyong; Lecrevisse, Thibault; Iwasa, Yukikazu

2017-06-01

This paper focuses on the construction and test results of Coil 2 that is part of a trio of nested coils composing the REBCO 800 MHz insert. Upon its completion, the REBCO 800 MHz insert will be placed in the bore of a 500 MHz low temperature superconducting (LTS) NMR magnet (L500) to form the MIT 1.3 GHz high-resolution NMR magnet. Coil 2 is a stack of 32 double pancake (DP) coils wound with 6-mm wide REBCO tape using the no-insulation (NI) technique. Each pancake is wound on a stainless steel inner supporting ring to prevent the collapsing of its crossover due to the external pressure exerted by the winding pack. Coil 2 will be constructed in the following sequence: 1) after winding each DP will be individually tested in a bath of liquid nitrogen at atmospheric pressure to determine its current carrying capabilities; 2) DPs will be then assembled as a stack with interconnecting joints, and 3) as in Coil 1, each pancake will be overbanded with a stainless steel tape, this time to a thickness of 5 mm, thickness determined by a stress analysis previously performed. Finally the fully assembled Coil 2 will be tested in liquid nitrogen at 77 K and then in liquid helium at 4.2 K. We present here details of the stress analysis leading to the sizing of the DP inner supporting stainless steel ring and of the overbanding thickness required. Test results include coil index, critical current, charging time constant.

Measurement of a Conduction Cooled Nb3Sn Racetrack Coil

NASA Astrophysics Data System (ADS)

Kim, HS; Kovacs, C.; Rochester, J.; Sumption, MD; Tomsic, M.; Peng, X.; Doll, D.

2017-12-01

Use of superconducting coils for wind turbines and electric aircraft is of interest because of the potential for high power density and weight reduction. Here we test a racetrack coil developed as a proof-of-concept for cryogen-free superconducting motors and generators. The coil was wound with 1209 m of 0.7-mm-diameter insulated tube-type Nb3Sn wire. The coil was epoxy-impregnated, instrumented, covered with numerous layers of aluminized mylar insulation, and inserted vertically into a dewar. The system was cooled to 4.2 K, and a few inches of liquid helium was allowed to collect at the bottom of the dewar but below the coil. The coil was cooled by conduction via copper cooling bars were attached to the coil but also were immersed in the liquid helium at their lower ends. Several current tests were performed on the coil, initially in voltage mode, and one run in current mode. The maximum coil Ic at 4.2 K was 480 A, generating 3.06 T at the surface of the coil. The coil met the design targets with a noticeable margin.

Superconducting magnet and cryostat for a space application

NASA Technical Reports Server (NTRS)

Pope, W. L.; Smoot, G. F.; Smith, L. H.; Taylor, C. E.

1975-01-01

The paper describes the design concepts, development, and testing of a superconducting coil and cryostat for an orbiting superconducting magnetic spectrometer. Several coils were subject to overall thermal performance and coil charging tests. The coils have low but persistent currents and have proven themselves to be rugged and reliable for mobile balloon flights. Satellite experiments will be conducted on a new, similar design.

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

Reiersen, W.; Heitzenroeder, P.; Neilson, G. H.

The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in partnership with the Oak Ridge National Laboratory (ORNL). The stellarator core is designed to produce a compact 3-D plasma that combines stellarator and tokamak physics advantages. The engineering challenges of NCSX stem from its complex geometry. From the project's start in April, 2003 to September, 2004, the fabrication specifications for the project's two long-lead components, the modular coil winding forms and the vacuum vessel, were developed. An industrial manufacturing R&D program refined the processes for their fabrication as well as production cost andmore » schedule estimates. The project passed a series of reviews and established its performance baseline with the Department of Energy. In September 2004, fabrication was approved and contracts for these components were awarded. The suppliers have completed the engineering and tooling preparations and are in production. Meanwhile, the project completed preparations for winding the coils at PPPL by installing a coil manufacturing facility and developing all necessary processes through R&D. The main activities for the next two years will be component manufacture, coil winding, and sub-assembly of the vacuum vessel and coil subsets. Machine sector sub-assembly, machine assembly, and testing will follow, leading to First Plasma in July 2009.« less

Archimedean Spiral Pairs with no Electrical Connections as a Passive Wireless Implantable Sensor

PubMed Central

Drazan, John F; Gunko, Aleksandra; Dion, Matthew; Abdoun, Omar; Cady, Nathaniel C; Connor, Kenneth A; Ledet, Eric H

2015-01-01

We have developed, modeled, fabricated, and tested a passive wireless sensor system that exhibits a linear frequency-displacement relationship. The displacement sensor is comprised of two anti-aligned Archimedean coils separated by an insulating dielectric layer. There are no electrical connections between the two coils and there are no onboard electronics. The two coils are inductively and capacitively coupled due to their close proximity. The sensor system is interrogated wirelessly by monitoring the return loss parameter from a vector network analyzer. The resonant frequency of the sensor is dependent on the displacement between the two coils. Due to changes in the inductive and capacitive coupling between the coils at different distances, the resonant frequency is modulated by coil separation. In a specified range, the frequency shift can be linearized with respect to coil separation. Batch fabrication techniques were used to fabricate copper coils for experimental testing with air as the dielectric. Through testing, we validated the performance of sensors as predicted within acceptable errors. Because of its simplicity, this displacement sensor has potential applications for in vivo sensing. PMID:27430033

Coiled-coil protein composition of 22 proteomes--differences and common themes in subcellular infrastructure and traffic control.

PubMed

Rose, Annkatrin; Schraegle, Shannon J; Stahlberg, Eric A; Meier, Iris

2005-11-16

Long alpha-helical coiled-coil proteins are involved in diverse organizational and regulatory processes in eukaryotic cells. They provide cables and networks in the cyto- and nucleoskeleton, molecular scaffolds that organize membrane systems and tissues, motors, levers, rotating arms, and possibly springs. Mutations in long coiled-coil proteins have been implemented in a growing number of human diseases. Using the coiled-coil prediction program MultiCoil, we have previously identified all long coiled-coil proteins from the model plant Arabidopsis thaliana and have established a searchable Arabidopsis coiled-coil protein database. Here, we have identified all proteins with long coiled-coil domains from 21 additional fully sequenced genomes. Because regions predicted to form coiled-coils interfere with sequence homology determination, we have developed a sequence comparison and clustering strategy based on masking predicted coiled-coil domains. Comparing and grouping all long coiled-coil proteins from 22 genomes, the kingdom-specificity of coiled-coil protein families was determined. At the same time, a number of proteins with unknown function could be grouped with already characterized proteins from other organisms. MultiCoil predicts proteins with extended coiled-coil domains (more than 250 amino acids) to be largely absent from bacterial genomes, but present in archaea and eukaryotes. The structural maintenance of chromosomes proteins and their relatives are the only long coiled-coil protein family clearly conserved throughout all kingdoms, indicating their ancient nature. Motor proteins, membrane tethering and vesicle transport proteins are the dominant eukaryote-specific long coiled-coil proteins, suggesting that coiled-coil proteins have gained functions in the increasingly complex processes of subcellular infrastructure maintenance and trafficking control of the eukaryotic cell.

Coiled-coil protein composition of 22 proteomes – differences and common themes in subcellular infrastructure and traffic control

PubMed Central

Rose, Annkatrin; Schraegle, Shannon J; Stahlberg, Eric A; Meier, Iris

2005-01-01

Background Long alpha-helical coiled-coil proteins are involved in diverse organizational and regulatory processes in eukaryotic cells. They provide cables and networks in the cyto- and nucleoskeleton, molecular scaffolds that organize membrane systems and tissues, motors, levers, rotating arms, and possibly springs. Mutations in long coiled-coil proteins have been implemented in a growing number of human diseases. Using the coiled-coil prediction program MultiCoil, we have previously identified all long coiled-coil proteins from the model plant Arabidopsis thaliana and have established a searchable Arabidopsis coiled-coil protein database. Results Here, we have identified all proteins with long coiled-coil domains from 21 additional fully sequenced genomes. Because regions predicted to form coiled-coils interfere with sequence homology determination, we have developed a sequence comparison and clustering strategy based on masking predicted coiled-coil domains. Comparing and grouping all long coiled-coil proteins from 22 genomes, the kingdom-specificity of coiled-coil protein families was determined. At the same time, a number of proteins with unknown function could be grouped with already characterized proteins from other organisms. Conclusion MultiCoil predicts proteins with extended coiled-coil domains (more than 250 amino acids) to be largely absent from bacterial genomes, but present in archaea and eukaryotes. The structural maintenance of chromosomes proteins and their relatives are the only long coiled-coil protein family clearly conserved throughout all kingdoms, indicating their ancient nature. Motor proteins, membrane tethering and vesicle transport proteins are the dominant eukaryote-specific long coiled-coil proteins, suggesting that coiled-coil proteins have gained functions in the increasingly complex processes of subcellular infrastructure maintenance and trafficking control of the eukaryotic cell. PMID:16288662

Coil geometry effects on scanning single-coil magnetic induction tomography

NASA Astrophysics Data System (ADS)

Feldkamp, Joe R.; Quirk, Stephen

2017-09-01

Alternative coil designs for single coil magnetic induction tomography are considered in this work, with the intention of improving upon the standard design used previously. In particular, we note that the blind spot associated with this coil type, a portion of space along its axis where eddy current generation can be very weak, has an important effect on performance. The seven designs tested here vary considerably in the size of their blind spot. To provide the most discerning test possible, we use laboratory phantoms containing feature dimensions similar to blind spot size. Furthermore, conductivity contrasts are set higher than what would occur naturally in biological systems, which has the effect of weakening eddy current generation at coil locations that straddle the border between high and low conductivity features. Image reconstruction results for the various coils show that coils with smaller blind spots give markedly better performance, though improvements in signal-to-noise ratio could alter that conclusion.

ETF magnet design alternatives for the national MHD program

NASA Astrophysics Data System (ADS)

Marston, P. G.; Thome, R. J.; Dawson, A. M.; Bobrov, E. S.; Hatch, A. M.

1981-01-01

Five superconducting magnet designs are evaluated for a 200 MWe test facility requiring a magnet with an on-axis field of 6 T, an inlet bore area of 4 sq m, storing 6 x 10 to the 9th J. The designs include a straightforward rectangular saddle coil set, a 'Cask' configuration based on staves and corner blocks as the main support structure, and an internally cooled, cabled superconductor to minimize the substructure and eliminate the helium vessel. Also, a modular design using six coils with individual helium vessels and an integrated structure produces a simplest configuration which utilizes a natural rectangular interface for packaging the MHD channel and its connections, and results in a lower capital cost.

Evidence-based pathology: umbilical cord coiling.

PubMed

Khong, T Y

2010-12-01

The generation of a pathology test result must be based on criteria that are proven to be acceptably reproducible and clinically relevant to be evidence-based. This review de-constructs the umbilical cord coiling index to illustrate how it can stray from being evidence-based. Publications related to umbilical cord coiling were retrieved and analysed with regard to how the umbilical coiling index was calculated, abnormal coiling was defined and reference ranges were constructed. Errors and other influences that can occur with the measurement of the length of the umbilical cord or of the number of coils can compromise the generation of the coiling index. Definitions of abnormal coiling are not consistent in the literature. Reference ranges defining hypocoiling or hypercoiling have not taken those potential errors or the possible effect of gestational age into account. Even the way numerical test results in anatomical pathology are generated, as illustrated by the umbilical coiling index, warrants a critical analysis into its evidence base to ensure that they are reproducible or free from errors.

Conductor and joint test results of JT-60SA CS and EF coils using the NIFS test facility

NASA Astrophysics Data System (ADS)

Obana, Tetsuhiro; Takahata, Kazuya; Hamaguchi, Shinji; Kizu, Kaname; Murakami, Haruyuki; Chikaraishi, Hirotaka; Noguchi, Hiroki; Kobuchi, Takashi; Moriuchi, Sadatomo; Imagawa, Shinsaku; Mito, Toshiyuki; Tsuchiya, Katsuhiko; Natsume, Kyohei; Yoshida, Kiyoshi; Nomoto, Kazuhiro; Kim, Tae-hyun

2016-01-01

In 2007, JAEA and NIFS launched the test project to evaluate the performance of cable-in-conduit (CIC) conductors and conductor joints for the JT-60SA CS and EF coils. In this project, conductor tests for four types of coil conductor and joint tests for seven types of conductor joint have been conducted for the past eight years using the NIFS test facility. As a result, the test project indicated that the CIC conductors and conductor joints fulfill the design requirement for the CS and EF coils. In addition, the NIFS test facility is expected to be utilized as the test facility for the development of a conductor and conductor joint for the purpose of the DEMO nuclear fusion power plant, provided that the required magnetic field strength is within 9 T.

Goddard Space Flight Center Spacecraft Magnetic Test Facility Restoration Project

NASA Technical Reports Server (NTRS)

Vernier, Robert; Bonalksy, Todd; Slavin, James

2004-01-01

The Goddard Space Flight Center Spacecraft Magnetic Test Facility (SMTF) was constructed in the 1960's for the purpose of simulating geomagnetic and interplanetary magnetic field environments. The facility includes a three axis Braunbek coil system consisting of 12 loops, 4 loops on each of the three orthogonal axes; a remote Earth field sensing magnetometer and servo controller; and a remote power control and instrumentation building. The inner coils of the Braunbek system are 42-foot in diameter with a 10-foot by 10-foot opening through the outer coils to accommodate spacecraft access into the test volume. The physical size and precision of the facility are matched by only two other such facilities in the world. The facility was used extensively from the late 1960's until the early 1990's when the requirement for spacecraft level testing diminished. New NASA missions planned under the Living with a Star, Solar Terrestrial Probes, Explorer, and New Millennium Programs include precision, high-resolution magnetometers to obtain magnetic field data that is critical to fulfilling their scientific mission. It is highly likely that future Lunar and Martian exploration missions will also use precision magnetometers to conduct geophysical magnetic surveys. To ensure the success of these missions, ground-testing using a magnetic test facility such as the GSFC SMTF will be required. This paper describes the history of the facility, the future mission requirements that have renewed the need for spacecraft level magnetic testing, and the plans for restoring the facility to be capable of performing to its original design specifications.

Goddard Space Flight Center Spacecraft Magnetic Test Facility Restoration Project

NASA Technical Reports Server (NTRS)

Vernier, Robert; Bonalosky, Todd; Slavin, James

2004-01-01

The Goddard Space Flight Center Spacecraft Magnetic Test Facility (SMTF) was constructed in the 1960's for the purpose of simulating geomagnetic and interplanetary magnetic field environments. The facility includes a three axis Braunbek coil system consisting of 12 loops, 4 loops on each of the three orthogonal axes; a remote Earth field sensing magnetometer and servo controller; and a remote power control and instrumentation building. The inner coils of the Braunbek system are 42-foot in diameter with a 10-foot by 10-foot opening through the outer coils to accommodate spacecraft access into the test volume. The physical size and precision of the facility are matched by only two other such facilities in the world. The facility was used extensively from the late 1960's until the early 1990's when the requirement for spacecraft level testing diminished. New NASA missions planned under the Living with a Star, Solar Terrestrial Probes, Explorer, and New Millennium Programs include precision, high-resolution magnetometers to obtain magnetic field data that is critical to fulfilling their scientific mission. It is highly likely that future Lunar and Martian exploration missions will also use precision magnetometers to conduct geophysical magnetic surveys. To ensure the success of these missions, ground testing using a magnetic test facility such as the GSFC SMTF will be required. This paper describes the history of the facility, the future mission requirements that have renewed the need for spacecraft level magnetic testing, and the plans for restoring the facility to be capable of performing to its original design specifications.

Coil-On-Plug Ignition for Oxygen/Methane Liquid Rocket Engines in Thermal-Vacuum Environments

NASA Technical Reports Server (NTRS)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX)/liquid methane (LCH4) rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/LCH4 propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. A coil-on-plug ignition system has been developed to successfully demonstrate ignition reliability at these conditions while preventing corona discharge issues. The ICPTA uses spark plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp -2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, hot-fire testing at Plum Brook demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/LCH4 propulsion systems in future spacecraft.

Coil-On-Plug Ignition for LOX/Methane Liquid Rocket Engines in Thermal Vacuum Environments

NASA Technical Reports Server (NTRS)

Melcher, John C.; Atwell, Matthew J.; Morehead, Robert L.; Hurlbert, Eric A.; Bugarin, Luz; Chaidez, Mariana

2017-01-01

A coil-on-plug ignition system has been developed and tested for Liquid Oxygen (LOX) / liquid methane rocket engines operating in thermal vacuum conditions. The igniters were developed and tested as part of the Integrated Cryogenic Propulsion Test Article (ICPTA), previously tested as part of the Project Morpheus test vehicle. The ICPTA uses an integrated, pressure-fed, cryogenic LOX/methane propulsion system including a reaction control system (RCS) and a main engine. The ICPTA was tested at NASA Glenn Research Center's Plum Brook Station in the Spacecraft Propulsion Research Facility (B-2) under vacuum and thermal vacuum conditions. In order to successfully demonstrate ignition reliability in the vacuum conditions and eliminate corona discharge issues, a coil-on-plug ignition system has been developed. The ICPTA uses spark-plug ignition for both the main engine igniter and the RCS. The coil-on-plug configuration eliminates the conventional high-voltage spark plug cable by combining the coil and the spark-plug into a single component. Prior to ICPTA testing at Plum Brook, component-level reaction control engine (RCE) and main engine igniter testing was conducted at NASA Johnson Space Center (JSC), which demonstrated successful hot-fire ignition using the coil-on-plug from sea-level ambient conditions down to 10(exp.-2) torr. Integrated vehicle hot-fire testing at JSC demonstrated electrical and command/data system performance. Lastly, Plum Brook testing demonstrated successful ignitions at simulated altitude conditions at 30 torr and cold thermal-vacuum conditions at 6 torr. The test campaign successfully proved that coil-on-plug technology will enable integrated LOX/methane propulsion systems in future spacecraft.

Mechanical Design of HD2, a 15 T Nb3Sn Dipole Magnet with a 35 mm Bore

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

Ferracin, P.; Bartlett, S.E.; Caspi, S.

2006-06-01

After the fabrication and test of HD1, a 16 T Nb{sub 3}Sn dipole magnet based on flat racetrack coil configuration, the Superconducting Magnet Program at Lawrence Berkeley National Laboratory (LBNL) is developing the Nb{sub 3}Sn dipole HD2. With a dipole field above 15 T, a 35 mm clear bore, and nominal field harmonics within a fraction of one unit, HD2 represents a further step towards the application of block-type coils to high-field accelerator magnets. The design features tilted racetrack-type ends, to avoid obstructing the beam path, and a 4 mm thick stainless steel tube, to support the coil during themore » preloading operation. The mechanical structure, similar to the one used for HD1, is based on an external aluminum shell pretensioned with pressurized bladders. Axial rods and stainless steel plates provide longitudinal support to the coil ends during magnet excitation. A 3D finite element analysis has been performed to evaluate stresses and deformations from assembly to excitation, with particular emphasis on conductor displacements due to Lorentz forces. Numerical results are presented and discussed.« less

Parametric Study of HTS Coil Quench Protection Strategies

NASA Astrophysics Data System (ADS)

Seibert, Joseph; Zarnstorff, Michael; Zhai, Yuhu

2016-10-01

Next generation fusion devices require high magnetic fields to adequately contain burning plasmas. Use of high temperature superconducting (HTS) coils to generate these magnetic fields would lower energy cost of operation as well as increase stability of the superconducting state compared to low temperature superconducting coils. However, use of HTS coils requires developing quench protection strategies to prevent damage to the coils. One technique involves the utilization of copper discs and other conductors mutually coupled to the HTS coil to quickly extract the current from the coil. Another technique allows conduction between HTS turns to reduce the current in the coil during quench. This project describes a parametric study of the HTS coil and resistive-conductor setup in order to determine limiting cases of the geometry in an attempt to optimize current extraction and coil protection during quench scenarios. This work was supported in part by the U.S. Department of Energy, Office of Science, Office of Workforce Development for Teachers and Scientists (WDTS) under the Science Undergraduate Laboratory Internship (SULI) program.

Test Result of the Short Models MQXFS3 and MQXFS5 for the HL-LHC Upgrade

DOE PAGES

Bajas, Hugues; Ambrosio, Giorgio; Ballarino, A.; ...

2018-02-27

In the framework of the High-Luminosity Large Hadron Collider, the installation of a new generation of quadrupole magnets is foreseen on each side of ATLAS and CMS experiments. The new magnets are based on Nbmore » $$_{3}$$Sn technology and shall be able to reach an ultimate current of 17.9 kA with a peak field of 12.3 T in the coil. In 2016 and 2017, the first two short models, called MQXFS3 and MQXFS5, have been tested at 4.2 and 1.9 K in the two new test benches at the European Organization for Nuclear Research. This paper presents the result of the quench performance of the two models; the first magnet reached nominal but failed to reach ultimate, showing detraining in one coil. MQXFS5 reached ultimate performance without any detraining phenomena, validating the PIT conductor used for the first time in this magnet program.« less

Test Result of the Short Models MQXFS3 and MQXFS5 for the HL-LHC Upgrade

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

Bajas, Hugues; Ambrosio, Giorgio; Ballarino, A.

In the framework of the High-Luminosity Large Hadron Collider, the installation of a new generation of quadrupole magnets is foreseen on each side of ATLAS and CMS experiments. The new magnets are based on Nbmore » $$_{3}$$Sn technology and shall be able to reach an ultimate current of 17.9 kA with a peak field of 12.3 T in the coil. In 2016 and 2017, the first two short models, called MQXFS3 and MQXFS5, have been tested at 4.2 and 1.9 K in the two new test benches at the European Organization for Nuclear Research. This paper presents the result of the quench performance of the two models; the first magnet reached nominal but failed to reach ultimate, showing detraining in one coil. MQXFS5 reached ultimate performance without any detraining phenomena, validating the PIT conductor used for the first time in this magnet program.« less

Finite element modelling of non-linear magnetic circuits using Cosmic NASTRAN

NASA Technical Reports Server (NTRS)

Sheerer, T. J.

1986-01-01

The general purpose Finite Element Program COSMIC NASTRAN currently has the ability to model magnetic circuits with constant permeablilities. An approach was developed which, through small modifications to the program, allows modelling of non-linear magnetic devices including soft magnetic materials, permanent magnets and coils. Use of the NASTRAN code resulted in output which can be used for subsequent mechanical analysis using a variation of the same computer model. Test problems were found to produce theoretically verifiable results.

Processing and plating helical metallic coils

NASA Technical Reports Server (NTRS)

1972-01-01

The results of research efforts to develop an optimized nickel cobalt coating suitable as a recording medium are outlined. The coating is to be used directly on a BeCu helical coil substrate of a helical coil NASA recorder. Specifically, efforts were made to: optimize the coating thickness; establish processes and techniques adaptable for the production of finalized plated helical coils; design and fabricate the equipment required for production and testing of the coils; and deliver finalized helical coils to NASA.

Testing of Compact Bolted Fasteners with Insulation and Friction-Enhanced Shims for NCSX

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

L. E. Dudek, J.H. Chrzanowski, G. Gettelfinger, P. Heitzenroeder, S. Jurczynski, M. Viola and K. Freudenberg

The fastening of the National Compact Stellarator Experiment's (NCSX) modular coils presented a number of engineering and manufacturing challenges due to the high magnetic forces, need to control induced currents, tight tolerances and restrictive space envelope. A fastening method using high strength studs, jack nuts, insulating spacers, bushings and alumina coated shims was developed which met the requirements. A test program was conducted to verify the design. The tests included measurements of flatness of the spacers, determination of contact area, torque vs. tension of the studs and jack nuts, friction coefficient tests on the alumina and G-10 insulators, electrical tests,more » and tension relaxation tests due to temperature excursions from room temperature to liquid nitrogen temperatures. This paper will describe the design and the results of the test program.« less

Stabilization of Tokamak Plasmas by the Addition of Nonaxisymmetric Coils

NASA Astrophysics Data System (ADS)

Reiman, Allan

2008-11-01

It has been recognized since the early days of the fusion program that stellarator coils can be used to stabilize current carrying, toroidal, magnetically confined plasmas.[1] More recently, it has been shown that the vertical mode in a tokamak can be stabilized by a relatively simple set of parallelogram-shaped, localized, nonaxisymmetric coils.[2] We show that by superposing sets of these parallelogram-shaped, nonaxisymmetric coils at different locations, it is possible to reproduce the coil current patterns for conventional stellarator coils as well as those for Furth-Hartman coils[3]. This allows us to gain insight into the physics of stabilization produced by various sets of nonaxisymmetric coils by analysis of the effect on stability of localized coils at differing locations. In particular, the relationship between the stabilization effect and the rotational transform generated by the nonaxisymmetric coils is clarified. [1] J. L. Johnson, C. R. Oberman, R. M. Kulsrud, and E. A. Frieman, Phys. Fluids 1, 281 (1958) [2] A. Reiman, Phys. Rev. Lett. 99, 135007, (2007). [3] H.P. Furth and C.W. Hartman, Phys. Fluids 11, 408 (1968).

Characterization and evaluation of a flexible MRI receive coil array for radiation therapy MR treatment planning using highly decoupled RF circuits.

PubMed

McGee, Kiaran P; Stormont, Robert S; Lindsay, Scott A; Taracila, Victor; Savitskij, Dennis; Robb, Fraser; Witte, Robert J; Kaufmann, Timothy J; Huston, John; Riederer, Stephen J; Borisch, Eric A; Rossman, Phillip J

2018-04-13

The growth in the use of magnetic resonance imaging (MRI) data for radiation therapy (RT) treatment planning has been facilitated by scanner hardware and software advances that have enabled RT patients to be imaged in treatment position while providing morphologic and functional assessment of tumor volumes and surrounding normal tissues. Despite these advances, manufacturers have been slow to develop radiofrequency (RF) coils that closely follow the contour of a RT patient undergoing MR imaging. Instead, relatively large form surface coil arrays have been adapted from diagnostic imaging. These arrays can be challenging to place on, and in general do not conform to the patient's body habitus, resulting in sub optimal image quality. The purpose of this study is to report on the characterization of a new flexible and highly decoupled RF coil for use in MR imaging of RT patients. Coil performance was evaluated by performing signal-to-noise ratio (SNR) and noise correlation measurements using two coil (SNR) and four coil (noise correlation) element combinations as a function of coil overlap distance and comparing these values to those obtained using conventional coil elements. In vivo testing was performed in both normal volunteers and patients using a four and 16 element RF coil. Phantom experiments demonstrate the highly decoupled nature of the new coil elements when compared to conventional RF coils, while in vivo testing demonstrate that these coils can be integrated into extremely flexible and form fitting substrates that follow the exact contour of the patient. The new coil design addresses limitations imposed by traditional surface coil arrays and have the potential to significantly impact MR imaging for both diagnostic and RT applications.

Characterization and evaluation of a flexible MRI receive coil array for radiation therapy MR treatment planning using highly decoupled RF circuits

NASA Astrophysics Data System (ADS)

McGee, Kiaran P.; Stormont, Robert S.; Lindsay, Scott A.; Taracila, Victor; Savitskij, Dennis; Robb, Fraser; Witte, Robert J.; Kaufmann, Timothy J.; Huston, John, III; Riederer, Stephen J.; Borisch, Eric A.; Rossman, Phillip J.

2018-04-01

The growth in the use of magnetic resonance imaging (MRI) data for radiation therapy (RT) treatment planning has been facilitated by scanner hardware and software advances that have enabled RT patients to be imaged in treatment position while providing morphologic and functional assessment of tumor volumes and surrounding normal tissues. Despite these advances, manufacturers have been slow to develop radiofrequency (RF) coils that closely follow the contour of a RT patient undergoing MR imaging. Instead, relatively large form surface coil arrays have been adapted from diagnostic imaging. These arrays can be challenging to place on, and in general do not conform to the patient’s body habitus, resulting in sub optimal image quality. The purpose of this study is to report on the characterization of a new flexible and highly decoupled RF coil for use in MR imaging of RT patients. Coil performance was evaluated by performing signal-to-noise ratio (SNR) and noise correlation measurements using two coil (SNR) and four coil (noise correlation) element combinations as a function of coil overlap distance and comparing these values to those obtained using conventional coil elements. In vivo testing was performed in both normal volunteers and patients using a four and 16 element RF coil. Phantom experiments demonstrate the highly decoupled nature of the new coil elements when compared to conventional RF coils, while in vivo testing demonstrate that these coils can be integrated into extremely flexible and form fitting substrates that follow the exact contour of the patient. The new coil design addresses limitations imposed by traditional surface coil arrays and have the potential to significantly impact MR imaging for both diagnostic and RT applications.

Investigation on quench initiation and propagation characteristics of GdBCO coil co-wound with a stainless steel tape as turn-to-turn metallic insulation.

PubMed

Kim, Y G; Song, J B; Choi, Y H; Yang, D G; Kim, S G; Lee, H G

2016-11-01

This paper investigates the quench initiation and propagation characteristics of a metallic insulation (MI) coil by conducting thermal quench tests for a GdBCO single-pancake coil co-wound with a stainless steel tape as the turn-to-turn MI. The test results confirmed that the MI coil exhibited superior thermal and electrical stabilities compared to the conventional coils co-wound with organic insulation material because the operating current could flow along the radial direction due to the existence of a turn-to-turn contact when a local hot spot was generated. The results of the quench test at a heater current (I h ) of 12, 13, and 14 A indicate that the MI coil possesses a self-protecting characteristic resulting from the "current bypass" through the turn-to-turn contact. However, the test coil was not self-protecting at I h = 15 A because the Joule heat energy generated by the radial current flow was not completely dissipated due to the characteristic resistance of the metallic insulation tape and the non-superconducting materials, including the substrate, stabilizer, and buffer layers within the high-temperature superconductor (HTS) tape. Even though the MI coil possesses superior thermal and electrical stability relative to those of conventional HTS coils co-wound with an organic material as turn-to-turn insulation, it is essential to consider the critical role of the Joule heat energy resulting from the operating current and stored magnetic energy as well as the characteristic resistances in order to further develop self-protective 2G HTS magnets.

Retrofitting coils

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

Merrill, D.G.

1995-12-01

This article provides guidelines for maintaining efficiency by determining which coils require replacement and the selection of replacement coils to match the originals in terms of size, performance, materials, and material thickness. Coils in the Rio Hondo College have been in use 24 years. The author recently found an installation where the coils installed 20 years ago look like new, which is the result of a highly effective preventive maintenance program. But these exceptions are countered by some installations lasting considerably less time. Periodic coil inspections are the best way to find leaks and deterioration. Leaking coils have an unhappymore » way of announcing their presence through unwanted water on ceilings, walls, and machine room floors. Minuscule streams of water impinge on nonwater-tight housings or are picked up in the air stream to leak out of the ductwork. Coil return bends and headers seem to have the greater incidence of failure and should be checked first for pinhole or joint leaks. Also, check along the points where the tubes penetrate the tube sheets. The coil headers should be checked as should the tubes along the front and backside of the coil. The more rows the coil has, the more difficult this latter assignment becomes.« less

Active Protection of an MgB2 Test Coil

PubMed Central

Park, Dong Keun; Hahn, Seungyong; Bascuñán, Juan; Iwasa, Yukikazu

2011-01-01

This paper presents results of a study, experimental and computational, of a detect-and-activate-the-heater protection technique applied to a magnesium diboride (MgB2) test coil operated in semi-persistent mode. The test coil with a winding ID of 25 cm and wound with ~500-m long reacted MgB2 wire was operated at 4.2 K immersed in a bath of liquid helium. In this active technique, upon the initiation of a “hot spot” of a length ~10 cm, induced by a “quench heater,” a “protection heater” (PH) of ~600-cm long planted within the test coil is activated. The normal zone created by the PH is large enough to absorb the test coil’s entire initial stored energy and still keeps the peak temperature within the winding below ~260 K. PMID:22081754

Design and test of a double-nuclear RF coil for 1H MRI and 13C MRSI at 7 T

NASA Astrophysics Data System (ADS)

Rutledge, Omar; Kwak, Tiffany; Cao, Peng; Zhang, Xiaoliang

2016-06-01

RF coil operation at the ultrahigh field of 7 T is fraught with technical challenges that limit the advancement of novel human in vivo applications at 7 T. In this work, a hybrid technique combining a microstrip transmission line and a lumped-element L-C loop coil to form a double-nuclear RF coil for proton magnetic resonance imaging and carbon magnetic resonance spectroscopy at 7 T was proposed and investigated. Network analysis revealed a high Q-factor and excellent decoupling between the coils. Proton images and localized carbon spectra were acquired with high sensitivity. The successful testing of this novel double-nuclear coil demonstrates the feasibility of this hybrid design for double-nuclear MR imaging and spectroscopy studies at the ultrahigh field of 7 T.

Persistent-current switch for pancake coils of rare earth-barium-copper-oxide high-temperature superconductor: Design and test results of a double-pancake coil operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K)

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

Qu, Timing; Michael, Philip C.; Bascuñán, Juan

2016-08-22

We present design and test results of a superconducting persistent current switch (PCS) for pancake coils of rare-earth-barium-copper-oxide, REBCO, high-temperature superconductor (HTS). Here, a REBCO double-pancake (DP) coil, 152-mm ID, 168-mm OD, 12-mm high, was wound with a no-insulation technique. We converted a ∼10-cm long section in the outermost layer of each pancake to a PCS. The DP coil was operated in liquid nitrogen (77–65 K) and in solid nitrogen (60–57 K). Over the operating temperature ranges of this experiment, the normal-state PCS enabled the DP coil to be energized; thereupon, the PCS resumed the superconducting state and the DP coil fieldmore » decayed with a time constant of 100 h, which would have been nearly infinite, i.e., persistent-mode operation, were the joint across the coil terminals superconducting.« less

Contemporary rates and outcomes of single- vs. dual-coil implantable cardioverter defibrillator lead implantation: data from the Israeli ICD Registry.

PubMed

Leshem, Eran; Suleiman, Mahmoud; Laish-Farkash, Avishag; Konstantino, Yuval; Glikson, Michael; Barsheshet, Alon; Goldenberg, Ilan; Michowitz, Yoav

2017-09-01

Dual-coil leads were traditionally considered standard of care due to lower defibrillation thresholds (DFT). Higher complication rates during extraction with parallel progression in implantable cardioverter defibrillator (ICD) technology raised questions on dual coil necessity. Prior substudies found no significant outcome difference between dual and single coils, although using higher rates of DFT testing then currently practiced. We evaluated the temporal trends in implantation rates of single- vs. dual-coil leads and determined the associated adverse clinical outcomes, using a contemporary nation-wide ICD registry. Between July 2010 and March 2015, 6343 consecutive ICD (n = 3998) or CRT-D (n = 2345) implantation patients were prospectively enrolled in the Israeli ICD Registry. A follow-up of at least 1 year of 2285 patients was available for outcome analysis. The primary endpoint was all-cause mortality. Single-coil leads were implanted in 32% of our cohort, 36% among ICD recipients, and 26% among CRT-D recipients. Secondary prevention indication was associated with an increased rate of dual-coil implantation. A significant decline in dual-coil leads with reciprocal incline of single coils was observed, despite low rates of DFT testing (11.6%) during implantation, which also declined from 31 to 2%. In the multivariate Cox model analysis, dual- vs. single-coil lead implantation was not associated with an increased risk of mortality [hazard ratio (HR) = 1.23; P= 0.33], heart failure hospitalization (HR = 1.34; P=0.13), appropriate (HR = 1.25; P= 0.33), or inappropriate ICD therapy (HR = 2.07; P= 0.12). Real-life rates of single-coil lead implantation are rising while adding no additional risk. These results of single-coil safety are reassuring and obtained, despite low and contemporary rates of DFT testing. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2016. For permissions please email: journals.permissions@oup.com.

Predicting helix orientation for coiled-coil dimers

PubMed Central

Apgar, James R.; Gutwin, Karl N.; Keating, Amy E.

2008-01-01

The alpha-helical coiled coil is a structurally simple protein oligomerization or interaction motif consisting of two or more alpha helices twisted into a supercoiled bundle. Coiled coils can differ in their stoichiometry, helix orientation and axial alignment. Because of the near degeneracy of many of these variants, coiled coils pose a challenge to fold recognition methods for structure prediction. Whereas distinctions between some protein folds can be discriminated on the basis of hydrophobic/polar patterning or secondary structure propensities, the sequence differences that encode important details of coiled-coil structure can be subtle. This is emblematic of a larger problem in the field of protein structure and interaction prediction: that of establishing specificity between closely similar structures. We tested the behavior of different computational models on the problem of recognizing the correct orientation - parallel vs. antiparallel - of pairs of alpha helices that can form a dimeric coiled coil. For each of 131 examples of known structure, we constructed a large number of both parallel and antiparallel structural models and used these to asses the ability of five energy functions to recognize the correct fold. We also developed and tested three sequenced-based approaches that make use of varying degrees of implicit structural information. The best structural methods performed similarly to the best sequence methods, correctly categorizing ∼81% of dimers. Steric compatibility with the fold was important for some coiled coils we investigated. For many examples, the correct orientation was determined by smaller energy differences between parallel and antiparallel structures distributed over many residues and energy components. Prediction methods that used structure but incorporated varying approximations and assumptions showed quite different behaviors when used to investigate energetic contributions to orientation preference. Sequence based methods were sensitive to the choice of residue-pair interactions scored. PMID:18506779

Measurement of heating coil temperature for e-cigarettes with a "top-coil" clearomizer.

PubMed

Chen, Wenhao; Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A; Kumagai, Kazukiyo

2018-01-01

To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a "top-coil" clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3-6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such "top-coil" clearomizers. This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices' ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating.

Experimental Test of Coupled Wave Model of Large Coils

DTIC Science & Technology

1985-06-01

46556 Abstract: Recent data from Time Domain Pulse Reflectometry experiments on a three turn coil in the form of a race track corroborate the...Domain Pulse Reflectometry experiments on a three turn coil in the form of a race track corroborate the theory of coupled wave model for large coils...Gabriel, "Coupled Wave Model for Large Magnet Coils", NASA Contractor Report 3332, National Aeronautics and Space Administration, Washington, DC

Application of superconducting coils to the NASA prototype magnetic balance

NASA Technical Reports Server (NTRS)

Haldeman, C. W.; Kraemer, R. A.; Phey, S. W.; Alishahi, M. M.; Covert, E. E.

1981-01-01

Application of superconducting coils to a general purpose magnetic balance was studied. The most suitable currently available superconducting cable for coils appears to be a bundle of many fine wires which are transposed and are mechanically confined. Sample coils were tested at central fields up to .5 Tesla, slewing rates up to 53 Tesla/ sec and frequencies up to 30 Hz. The ac losses were measured from helium boil-off and were approximately 20% higher than those calculated. Losses were dominated by hysteresis and a model for loss calculation which appears suitable for design purposes is presented along with computer listings. Combinations of two coils were also tested and interaction losses are reported. Two feasible geometries are also presented for prototype magnetic balance using superconductors.

ac Modeling and impedance spectrum tests of the superconducting magnetic field coils for the Wendelstein 7-X fusion experiment.

PubMed

Ehmler, Hartmut; Köppen, Matthias

2007-10-01

The impedance spectrum test was employed for detection of short circuits within Wendelstein 7-X (W7-X) superconducting magnetic field coils. This test is based on measuring the complex impedance over several decades of frequency. The results are compared to predictions of appropriate electrical equivalent circuits of coils in different production states or during cold test. When the equivalent circuit is not too complicated the impedance can be represented by an analytic function. A more detailed analysis is performed with a network simulation code. The overall agreement of measured and calculated or simulated spectra is good. Two types of short circuits which appeared are presented and analyzed. The detection limit of the method is discussed. It is concluded that combined high-voltage ac and low-voltage impedance spectrum tests are ideal means to rule out short circuits in the W7-X coils.

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

S. Chouhan, J. DeKamp, A. Zeller, P. Brindza, S. Lassiter, M. Fowler, E. Sun

A collaboration between NSCL and Jlab has developed the reference design and coil winding for Jlab's Super High Momentum Spectrometer (SHMS) horizontal bend magnet. A warm iron ??C?? type superferric dipole magnet will bend the 12 GeV/c particles horizontally by 3?? to allow the SHMS to reach angles as low as 5.5??. This requires an integral field strength of up to 2.1 T.m. The major challenges are the tight geometry, high and unbalanced forces and a required low fringe field in primary beam path. A coil design based on flattened SSC Rutherford cable that provides a large current margin andmore » commercially available fiberglass prepreg epoxy tape has been developed. A complete test coil has been wound and will be cold tested. This paper present the modified magnet design includes coil forces, coil restraint system and fringe field. In addition, coil properties, quench calculations and the full mechanical details are also presented.« less

Transient Heat Transfer in TCAP Coils

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

Steimke, J.L.

1999-03-09

The Thermal Cycling Absorption Process (TCAP) is used to separate isotopes of hydrogen. TCAP involves passing a stream of mixed hydrogen isotopes through palladium deposited on kieselguhr (Pd/k) while cycling the temperature of the Pd/k. Kieselguhr is a silica mineral also called diatomite. To aid in the design of a full scale facility, the Thermal Fluids Laboratory was used by the Chemical and Hydrogen Technology Section to compare the heat transfer properties of three different configurations of stainless steel coils containing kieselguhr and helium. Testing of coils containing Pd/k and hydrogen isotopes would have been more prototypical but would havemore » been too expensive. Three stainless steel coils filled with kieselguhr were tested; one made from 2.0 inch diameter tubing, one made from 2.0 inch diameter tubing with foam copper embedded in the kieselguhr and one made from 1.25 inch diameter tubing. It was known prior to testing that increasing the tubing diameter from 1.25 inch to 2.0 inch would slow the rate of temperature change. The primary purpose of the testing was to measure to what extent the presence of copper foam in a 2.0" tubing coil would compensate for the effect of larger diameter. Each coil was connected to a pressure gage and the coil was evacuated and backfilled with helium gas. Helium was used instead of a mixture of hydrogen isotopes for reasons of safety. Each coil was quickly immersed in a stirred bath of ethylene glycol at a temperature of approximately 100 degrees Celsius. The coil pressure increased, reflecting the increase in average temperature of its contents. The pressure transient was recored as a function of time after immersion. Because of the actual process will use Pd/k instead of kieselguhr, additional tests were run to determine the differences in thermal properties between the two materials. The method was to position a thermocouple at the center of a hollow sphere and pack the sphere with Pd/k. The sphere was sealed, quickly submerged in a bath of boiling water and the temperature transient was recorded. There sphere was then opened, the Pd/k was replaced with kieselguhr and the transient was repeated. The response was a factor of 1.4 faster for Pd/k than for kieselguhr, implying a thermal diffusivity approximately 40 percent higher than for kieselguhr. Another implication is that the transient tests with the coils would have proceeded faster if the coils had been filled with Pd/k rather than kieselguhr.« less

Transient Heat Transfer in TCAP Coils

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

Steimke, J.L.

1999-03-09

The Thermal Cycling Absorption Process (TCAP) is used to separate isotopes of hydrogen. TCAP involves passing a stream of mixed hydrogen isotopes through palladium deposited on kieselguhr (Pd/k) while cycling the temperature of the Pd/k. Kieselguhr is a silica mineral also called diatomite. To aid in the design of a full scale facility, the Thermal Fluids Laboratory was used by the Chemical and Hydrogen Technology Section to compare the heat transfer properties of three different configurations of stainless steel coils containing kieselguhr and helium. Testing of coils containing Pd/k and hydrogen isotopes would have been more prototypical but would havemore » been too expensive. Three stainless steel coils filled with kieselguhr were tested; one made from 2.0 inch diameter tubing, one made from 2.0 inch diameter tubing with foam copper embedded in the kieselguhr and one made from 1.25 inch diameter tubing. It was known prior to testing that increasing the tubing diameter from 1.25 inch to 2.0 inch would slow the rate of temperature change. The primary purpose of the testing was to measure to what extent the presence of copper foam in a 2.0 tubing coil would compensate for the effect of larger diameter. Each coil was connected to a pressure gage and the coil was evacuated and backfilled with helium gas. Helium was used instead of a mixture of hydrogen isotopes for reasons of safety. Each coil was quickly immersed in a stirred bath of ethylene glycol at a temperature of approximately 100 degrees Celsius. The coil pressure increased, reflecting the increase in average temperature of its contents. The pressure transient was recored as a function of time after immersion. Because of the actual process will use Pd/k instead of kieselguhr, additional tests were run to determine the differences in thermal properties between the two materials. The method was to position a thermocouple at the center of a hollow sphere and pack the sphere with Pd/k. The sphere was sealed, quickly submerged in a bath of boiling water and the temperature transient was recorded. There sphere was then opened, the Pd/k was replaced with kieselguhr and the transient was repeated. The response was a factor of 1.4 faster for Pd/k than for kieselguhr, implying a thermal diffusivity approximately 40 percent higher than for kieselguhr. Another implication is that the transient tests with the coils would have proceeded faster if the coils had been filled with Pd/k rather than kieselguhr.« less

Static Measurements on HTS Coils of Fully Superconducting AC Electric Machines for Aircraft Electric Propulsion System

NASA Technical Reports Server (NTRS)

Choi, Benjamin B.; Hunker, Keith R.; Hartwig, Jason; Brown, Gerald V.

2017-01-01

The NASA Glenn Research Center (GRC) has been developing the high efficiency and high-power density superconducting (SC) electric machines in full support of electrified aircraft propulsion (EAP) systems for a future electric aircraft. A SC coil test rig has been designed and built to perform static and AC measurements on BSCCO, (RE)BCO, and YBCO high temperature superconducting (HTS) wire and coils at liquid nitrogen (LN2) temperature. In this paper, DC measurements on five SC coil configurations of various geometry in zero external magnetic field are measured to develop good measurement technique and to determine the critical current (Ic) and the sharpness (n value) of the super-to-normal transition. Also, standard procedures for coil design, fabrication, coil mounting, micro-volt measurement, cryogenic testing, current control, and data acquisition technique were established. Experimentally measured critical currents are compared with theoretical predicted values based on an electric-field criterion (Ec). Data here are essential to quantify the SC electric machine operation limits where the SC begins to exhibit non-zero resistance. All test data will be utilized to assess the feasibility of using HTS coils for the fully superconducting AC electric machine development for an aircraft electric propulsion system.

The utility of dual-energy CT for metal artifact reduction from intracranial clipping and coiling.

PubMed

Mera Fernández, D; Santos Armentia, E; Bustos Fiore, A; Villanueva Campos, A M; Utrera Pérez, E; Souto Bayarri, M

2018-04-23

To assess the ability of dual-energy CT (DECT) to reduce metal-related artifacts in patients with clips and coils in head CT angiography, and to analyze the differences in this reduction between both type of devices. Thirteen patients (6 clips, 7 coils) were selected and retrospectively analized. Virtual monoenergetic images (MEI) with photon energies from 40 to 150 keV were obtained. Noise was measured at the area of maximum artifact. Subjective evaluation of streak artifact was performed by two radiologists independently. Differences between noise values in all groups were tested by using the ANOVA test. Mann-Whitney U test was used to compare the differences between clips and coils. Coheńs κ statistic was used to determine interobserver agreement. The lowest noise value was observed at high energy levels (p<0,05). Noise was higher in the coil group than in the clip group (p<0.001). Interobserver agreement was good (κ=0.72). TCED with MEI helps to minimize the artifact from clips ands coils in patients who undergo head CT angiography. The reduction of the artifact is greater in patients with surgical clipping than in patients with endovascular coiling. Copyright © 2018 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

Increasing the affinity of selective bZIP-binding peptides through surface residue redesign.

PubMed

Kaplan, Jenifer B; Reinke, Aaron W; Keating, Amy E

2014-07-01

The coiled-coil dimer is a prevalent protein interaction motif that is important for many cellular processes. The basic leucine-zipper (bZIP) transcription factors are one family of proteins for which coiled-coil mediated dimerization is essential for function, and misregulation of bZIPs can lead to disease states including cancer. This makes coiled coils attractive protein-protein interaction targets to disrupt using engineered molecules. Previous work designing peptides to compete with native coiled-coil interactions focused primarily on designing the core residues of the interface to achieve affinity and specificity. However, folding studies on the model bZIP GCN4 show that coiled-coil surface residues also contribute to binding affinity. Here we extend a prior study in which peptides were designed to bind tightly and specifically to representative members of each of 20 human bZIP families. These "anti-bZIP" peptides were designed with an emphasis on target-binding specificity, with contributions to design-target specificity and affinity engineered considering only the coiled-coil core residues. High-throughput testing using peptide arrays indicated many successes. We have now measured the binding affinities and specificities of anti-bZIPs that bind to FOS, XBP1, ATF6, and CREBZF in solution and tested whether redesigning the surface residues can increase design-target affinity. Incorporating residues that favor helix formation into the designs increased binding affinities in all cases, providing low-nanomolar binders of each target. However, changes in surface electrostatic interactions sometimes changed the binding specificity of the designed peptides. © 2014 The Protein Society.

Multi-turn transmit coil to increase b1 efficiency in current source amplification.

PubMed

Gudino, N; Griswold, M A

2013-04-01

A multi-turn transmit surface coil design was presented to improve B1 efficiency when used with current source amplification. Three different coil designs driven by an on-coil current-mode class-D amplifier with current envelope feedback were tested on the benchtop and through imaging in a 1.5 T scanner. Case temperature of the power field-effect transistor at the amplifier output stage was measured to evaluate heat dissipation for the different current levels and coil configurations. In addition, a lower power rated device was tested to exploit the potential gain in B1 obtained with the multi-turn coil. As shown both on the benchtop and in a 1.5 T scanner, B1 was increased by almost 3-fold without increasing heat dissipation on the power device at the amplifier's output using a multi-turn surface coil. Similar gain was obtained when connecting a lower power rated field-effect transistor to the multi-turn coil. In addition to reduce heat dissipation per B1 in the device, higher B1 per current efficiency allows the use of field-effect transistors with lower current ratings and lower port capacitances, which could improve the overall performance of the on-coil current source transmit system. Copyright © 2013 Wiley Periodicals, Inc.

Multi-turn transmit coil to increase B1 efficiency in current source amplification

PubMed Central

Gudino, N.; Griswold, M.A.

2013-01-01

Purpose A multi-turn transmit surface coil design was presented to improve B1 efficiency when used with current source amplification. Methods Three different coil designs driven by an on-coil current-mode class-D (CMCD) amplifier with current envelope feedback were tested on the benchtop and through imaging in a 1.5 T scanner. Case temperature of the power field-effect transistor (FET) at the amplifier output stage was measured to evaluate heat dissipation for the different current levels and coil configurations. In addition, a lower power rated device was tested to exploit the potential gain in B1 obtained with the multi-turn coil. Results As shown both on the benchtop and in a 1.5 T scanner, B1 was increased by almost three-fold without increasing heat dissipation on the power device at the amplifier's output using a multi-turn surface coil. Similar gain was obtained when connecting a lower power rated FET to the multi-turn coil. Conclusion In addition to reduce heat dissipation per B1 in the device, higher B1 per current efficiency allows the use of FETs with lower current ratings and lower port capacitances which could improve the overall performance of the on-coil current source transmit system. PMID:23401060

Advanced Geophysical Classification with the Marine Towed Array

NASA Astrophysics Data System (ADS)

Steinhurst, D.; Harbaugh, G.; Keiswetter, D.; Bell, T. W.; Massey, G.; Wright, D.

2017-12-01

The Marine Towed Array, or MTA, is an underwater dual-mode sensor array that has been successfully deployed at multiple marine venues in support of Strategic Environmental Research and Development Program (SERDP) and Environmental Security Technology Certification Program (ESTCP) demonstrations beginning in 2004. It provided both marine electromagnetic and marine magnetic sensors for detection and mapping of underwater UXO. The EMI sensor array was based on older technology, which in several ESTCP demonstrations has not been able to support advanced geophysical classification (AGC). Under ESTCP funding, the U.S. Naval Research Laboratory is in the process of upgrading the MTA with modern, advanced electromagnetic (EMI) electronics and replacing the sensor array with a modern, multistatic array design. A half-scale version of the proposed array has been built and tested on land. Six tri-axial receiver cubes were placed inside two- and three- transmit coil configurations in equivalent positions to design locations for the MTA wing. The responses of a variety of munitions items and test spheres were measured over a range of target-to-array geometries and in both static and simulated dynamic data collection modes. The multi-transmit coil configuration was shown to provide enhanced single-pass classification performance over the original single coil design, particularly as a function of target location relative to the centerline. The ability to go beyond anomaly detection and additionally classify detected anomalies from survey data would dramatically improve the state of the art for underwater UXO remediation by reducing costs and improving the efficiency of these efforts. The results of our efforts to return the MTA to service and validating the new EMI array's design for UXO detection and classification in the underwater environment will be the focus of this presentation.

Impact of magnetic field strength and receiver coil in ocular MRI: a phantom and patient study.

PubMed

Erb-Eigner, K; Warmuth, C; Taupitz, M; Willerding, G; Bertelmann, E; Asbach, P

2013-09-01

Generally, high-resolution MRI of the eye is performed with small loop surface coils. The purpose of this phantom and patient study was to investigate the influence of magnetic field strength and receiver coils on image quality in ocular MRI. The eyeball and the complex geometry of the facial bone were simulated by a skull phantom with swine eyes. MR images were acquired with two small loop surface coils with diameters of 4 cm and 7 cm and with a multi-channel head coil at 1.5 and 3 Tesla, respectively. Furthermore, MRI of the eye was performed prospectively in 20 patients at 1.5 Tesla (7 cm loop surface coil) and 3 Tesla (head coil). These images were analysed qualitatively and quantitatively and statistical significance was tested using the Wilcoxon-signed-rank test (a p-value of less than 0.05 was considered to indicate statistical significance). The analysis of the phantom images yielded the highest mean signal-to-noise ratio (SNR) at 3 Tesla with the use of the 4 cm loop surface coil. In the phantom experiment as well as in the patient studies the SNR was higher at 1.5 Tesla by applying the 7 cm surface coil than at 3 Tesla by applying the head coil. Concerning the delineation of anatomic structures no statistically significant differences were found. Our results show that the influence of small loop surface coils on image quality (expressed in SNR) in ocular MRI is higher than the influence of the magnetic field strength. The similar visibility of detailed anatomy leads to the conclusion that the image quality of ocular MRI at 3 Tesla remains acceptable by applying the head coil as a receiver coil. © Georg Thieme Verlag KG Stuttgart · New York.

Mechanical and electrical performance characterization of partial mock-up of the ITER PF6 coil tail

NASA Astrophysics Data System (ADS)

Zhang, Z.; Song, Y.; Wu, H.; Zhang, M.; Xie, Y.; Hu, B.; Liu, F.; Shen, G.; Wu, W.; Lu, K.; Wei, J.; Bilbao, M.; Peñate, J.; Readman, P.; Sborchia, C.; Valente, P.; Smith, K.

2017-12-01

International Thermonuclear Experimental Reactor (ITER) is a full superconducting coil tokamak. The tail is an important component of Poloidal Field (PF) coil, of which the main functions are to provide the electrical isolation and transfer the longitudinal load from the last turn to the last-but-one turn. The paper focuses on an optimized mechanical structure of PF6 coil tail, which is made up of two main parts. One was welded to the last turn and the other was welded to the last-but-one turn. Both of them were connected by the mechanical coupling. The electrical isolation between the two parts was maintained by a strap made of insulating composite. In addition, as the PF6 coil is operated under the cyclic electromagnetic load during the tokamak operation, the fatigue property of the tail should be assessed and qualified at low temperature. Moreover, taking into consideration the complexity of the insulation winding process which is performed in a confined space, the wrapping process of the insulation needs to be established. Meanwhile, the high voltage (HV) tests of the tail insulation, including the direct current (DC) and alternating current (AC) tests, need to be assessed before and after the fatigue test. In this paper, a fully bonded PF6 coil tail partial mock-up (not including the weld of the tail to the last conductor turn) was designed and manufactured by simulating the actual manufacturing processes. In addition, the fatigue tests on the sample were carried out at 77 K, and the results showed the sample had good and stable fatigue properties at cryogenic temperature. The HV tests before and after the fatigue test, also including the final 30 kV breakdown DC test after the fatigue test, were carried out. The test results satisfied the requirements of ITER and were discussed in depth. Finally, the sample was destructively inspected to validate the integrity of the insulation by mechanical cross sectioning, and no voids and cracks were observed. Therefore it can be verified from the test results that the designed PF6 coil tail has good comprehensive properties, which can be applied to the formal production of the PF6 coil.

SOLDESIGN user's manual copyright

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

Pillsbury, R.D. Jr.

1991-02-01

SOLDESIGN is a general purpose program for calculating and plotting magnetic fields, Lorentz body forces, resistances and inductances for a system of coaxial uniform current density solenoidal elements. The program was originally written in 1980 and has been evolving ever since. SOLDESIGN can be used with either interactive (terminal) or file input. Output can be to the terminal or to a file. All input is free-field with comma or space separators. SOLDESIGN contains an interactive help feature that allows the user to examine documentation while executing the program. Input to the program consists of a sequence of word commands andmore » numeric data. Initially, the geometry of the elements or coils is defined by specifying either the coordinates of one corner of the coil or the coil centroid, a symmetry parameter to allow certain reflections of the coil (e.g., a split pair), the radial and axial builds, and either the overall current density or the total ampere-turns (NI). A more general quadrilateral element is also available. If inductances or resistances are desired, the number of turns must be specified. Field, force, and inductance calculations also require the number of radial current sheets (or integration points). Work is underway to extend the field, force, and, possibly, inductances to non-coaxial solenoidal elements.« less

Magnetic suspension and balance system advanced study

NASA Technical Reports Server (NTRS)

Boom, R. W.; Eyssa, Y. M.; Mcintosh, G. E.; Abdelsalam, M. K.

1985-01-01

An improved compact design for a superconducting magnetic suspension and balance system for an 8 ft. x 8 ft. transonic wind tunnel is developed. The original design of an MSBS in NASA Cr-3802 utilized 14 external superconductive coils and a superconductive solenoid in the airplane test model suspended in a wind tunnel. The improvements are in the following areas: test model solenoid options, dynamic force limits on the model, magnet cooling options, structure and cryogenic designs, power supply specifications, and cost and performance evaluations. The improvements are: MSBS cost reduction of 28%, weight; reduction of 43%, magnet system ampere-meter reduction of 38%, helium liquifier capacity reduction by 33%, magnet system stored energy reduction by 55%, AC loss to liquid helium reduced by 76%, system power supply reduced by 68%, test coil pole strength increased by 19%, wing magnetization increased by 40%, and control frequency limit increased by 200% from 10 Hz to 30 Hz. The improvements are due to: magnetic holmium coil forms in the test model, better rare earth permanent magnets in the wings, fiberglass-epoxy structure replacing stainless steel, better coil configuration, and new saddle roll coil design.

Peripheral Nerve Stimulation Characteristics of an Asymmetric Head-Only Gradient Coil Compatible with a High-Channel-Count Receiver Array

PubMed Central

Lee, Seung-Kyun; Mathieu, Jean-Baptiste; Graziani, Dominic; Piel, Joseph; Budesheim, Eric; Fiveland, Eric; Hardy, Christopher J.; Tan, Ek Tsoon; Amm, Bruce; Foo, Thomas K.-F; Bernstein, Matt A.; Huston, John; Shu, Yunhong; Schenck, John F.

2015-01-01

Purpose To characterize peripheral nerve stimulation (PNS) of an asymmetric head-only gradient coil that is compatible with a commercial high-channel-count receive-only array. Methods Two prototypes of an asymmetric head-only gradient coil set, with 42-cm inner diameter, were constructed for brain imaging at 3T with maximum performance specifications of up to 85 mT/m and 708 T/m/s. 24 volunteer tests were performed to measure PNS thresholds with the transverse (X, left/right; Y, anterior/posterior) gradient coils of both prototypes. 14 volunteers were also tested for the Z-gradient PNS in the second prototype, and were additionally scanned with high-slew-rate EPI immediately after the PNS tests. Results For both prototypes, the Y-gradient PNS threshold was markedly higher than the X-gradient. The Z-gradient threshold was intermediate between those for the X- and Y-coils. Out of the 24 volunteer subjects, only two experienced Y-gradient PNS at 80 mT/m, 500 T/m/s. All volunteers underwent the EPI scan without PNS when the readout direction was set to A/P. Conclusion Measured PNS characteristics of asymmetric head-only gradient coil prototypes indicate that such coils, especially in the A/P direction, can be used for fast EPI readout in high-performance neuroimaging scans with substantially reduced PNS concerns compared to conventional whole-body gradient coils. PMID:26628078

Feasibility study of a new RF coil design for prostate MRI

NASA Astrophysics Data System (ADS)

Ha, Seunghoon; Roeck, Werner W.; Cho, Jaedu; Nalcioglu, Orhan

2014-09-01

The combined use of a torso-pelvic RF array coil and endorectal RF coil is the current state-of-the-art in prostate MRI. The endorectal coil provides high detection sensitivity to acquire high-spatial resolution images and spectroscopic data, while the torso-pelvic coil provides large coverage to assess pelvic lymph nodes and pelvic bones for metastatic disease. However, the use of an endorectal coil is an invasive procedure that presents difficulties for both patients and technicians. In this study, we propose a novel non-invasive RF coil design that can provide both image signal to noise ratio and field of view coverage comparable to the combined torso-pelvic and endorectal coil configuration. A prototype coil was constructed and tested using a pelvic phantom. The results demonstrate that this new design is a viable alternative for prostate MRI

Laterality in coiling behaviour of snakes: another interpretation.

PubMed

Heatwole, Harold; King, Peter; Levine, Samuel G

2007-11-01

The direction of coiling was periodically recorded for two species of viperid snakes--copperheads (Agkistrodon contortrix) and cottonmouths (Agkistrodon piscivorus). Overall, neither species showed a significant preference for coiling in a particular direction. Only 1 of 22 snakes exhibited an individual preference, a result within expectation for random direction of coiling when using a 5% rejection level for statistical testing. A previously published claim for laterality in coiling direction by cottonmouths presented similar results but came to the opposite conclusion. The data from the combined studies suggest that if laterality in coiling direction does occur, it is extremely weak and inconsistent.

Experiment of low resistance joints for the ITER correction coil.

PubMed

Liu, Huajun; Wu, Yu; Wu, Weiyue; Liu, Bo; Shi, Yi; Guo, Shuai

2013-01-01

A test method was designed and performed to measure joint resistance of the ITER correction coil (CC) in liquid helium (LHe) temperature. A 10 kA superconducting transformer was manufactured to provide the joints current. The transformer consisted of two concentric layer-wound superconducting solenoids. NbTi superconducting wire was wound in the primary coil and the ITER CC conductor was wound in the secondary coil. The primary and the secondary coils were both immersed in liquid helium of a 300 mm useful bore diameter cryostat. Two ITER CC joints were assembled in the secondary loop and tested. The current of the secondary loop was ramped to 9 kA in several steps. The two joint resistances were measured to be 1.2 nΩ and 1.65 nΩ, respectively.

Improved multi-directional eddy current inspection test apparatus for detecting flaws in metal articles

DOEpatents

Nance, Roy A.; Hartley, William H.; Caffarel, Alfred J.

1984-01-01

Apparatus is described for detecting flaws in a tubular workpiece in a single scan. The coils of a dual coil bobbin eddy current inspection probe are wound at a 45.degree. angle to the transverse axis of the probe, one coil having an angular position about the axis about 90.degree. relative to the angular position of the other coil, and the angle of intersection of the planes containing the coils being about 60.degree..

Measurement of heating coil temperature for e-cigarettes with a “top-coil” clearomizer

PubMed Central

Wang, Ping; Ito, Kazuhide; Fowles, Jeff; Shusterman, Dennis; Jaques, Peter A.; Kumagai, Kazukiyo

2018-01-01

Objectives To determine the effect of applied power settings, coil wetness conditions, and e-liquid compositions on the coil heating temperature for e-cigarettes with a “top-coil” clearomizer, and to make associations of coil conditions with emission of toxic carbonyl compounds by combining results herein with the literature. Methods The coil temperature of a second generation e-cigarette was measured at various applied power levels, coil conditions, and e-liquid compositions, including (1) measurements by thermocouple at three e-liquid fill levels (dry, wet-through-wick, and full-wet), three coil resistances (low, standard, and high), and four voltage settings (3–6 V) for multiple coils using propylene glycol (PG) as a test liquid; (2) measurements by thermocouple at additional degrees of coil wetness for a high resistance coil using PG; and (3) measurements by both thermocouple and infrared (IR) camera for high resistance coils using PG alone and a 1:1 (wt/wt) mixture of PG and glycerol (PG/GL). Results For single point thermocouple measurements with PG, coil temperatures ranged from 322 ‒ 1008°C, 145 ‒ 334°C, and 110 ‒ 185°C under dry, wet-through-wick, and full-wet conditions, respectively, for the total of 13 replaceable coil heads. For conditions measured with both a thermocouple and an IR camera, all thermocouple measurements were between the minimum and maximum across-coil IR camera measurements and equal to 74% ‒ 115% of the across-coil mean, depending on test conditions. The IR camera showed details of the non-uniform temperature distribution across heating coils. The large temperature variations under wet-through-wick conditions may explain the large variations in formaldehyde formation rate reported in the literature for such “top-coil” clearomizers. Conclusions This study established a simple and straight-forward protocol to systematically measure e-cigarette coil heating temperature under dry, wet-through-wick, and full-wet conditions. In addition to applied power, the composition of e-liquid, and the devices’ ability to efficiently deliver e-liquid to the heating coil are important product design factors effecting coil operating temperature. Precautionary temperature checks on e-cigarettes under manufacturer-recommended normal use conditions may help to reduce the health risks from exposure to toxic carbonyl emissions associated with coil overheating. PMID:29672571

46 CFR 64.83 - Hydrostatic test.

Code of Federal Regulations, 2010 CFR

2010-10-01

..., the heating coil passing a hydrostatic test at a pressure of 200 psig or more or 50 percent or more above the rated pressure of the coil, whichever is greater. (b) If the tank passes the hydrostatic test... 46 Shipping 2 2010-10-01 2010-10-01 false Hydrostatic test. 64.83 Section 64.83 Shipping COAST...

Superconducting magnet

NASA Technical Reports Server (NTRS)

1985-01-01

Extensive computer based engineering design effort resulted in optimization of a superconducting magnet design with an average bulk current density of approximately 12KA/cm(2). Twisted, stranded 0.0045 inch diameter NbTi superconductor in a copper matrix was selected. Winding the coil from this bundle facilitated uniform winding of the small diameter wire. Test coils were wound using a first lot of the wire. The actual packing density was measured from these. Interwinding voltage break down tests on the test coils indicated the need for adjustment of the wire insulation on the lot of wire subsequently ordered for construction of the delivered superconducting magnet. Using the actual packing densities from the test coils, a final magnet design, with the required enhancement and field profile, was generated. All mechanical and thermal design parameters were then also fixed. The superconducting magnet was then fabricated and tested. The first test was made with the magnet immersed in liquid helium at 4.2K. The second test was conducted at 2K in vacuum. In the latter test, the magnet was conduction cooled from the mounting flange end.

Cross-axis synchronous flow-through coil planet centrifuge for large-scale preparative counter-current chromatography. III. Performance of large-bore coils in slow planetary motion.

PubMed

Ito, Y; Zhang, T Y

1988-11-25

A preparative capability of the present cross-axis synchronous flow-through coil planet centrifuge was demonstrated with 0.5 cm I.D. multilayer coils. Results of the model studies with short coils indicated that the optimal separations are obtained at low revolutional speeds of 100-200 rpm in both central and lateral coil positions. Preparative separations were successfully performed on 2.5-10 g quantities of test samples in a pair of multilayer coils connected in series with a total capacity of 2.5 l. The sample loading capacity will be scaled up in several folds by increasing the column width.

Test of an 8.66-T REBCO Insert Coil with Overbanding Radial Build for a 1.3-GHz LTS/HTS NMR Magnet.

PubMed

Qu, Timing; Michael, Philip C; Bascuñán, Juan; Lécrevisse, Thibault; Guan, Mingzhi; Hahn, Seungyong; Iwasa, Yukikazu

2017-06-01

A 1.3-GHz/54-mm LTS/HTS NMR magnet, assembled with a 3-coil (Coils 1-3) 800-MHz HTS insert in a 500-MHz LTS NMR magnet, is under construction. The innermost HTS insert Coil 1 has a stack of 26 no-insulation (NI) double pancake (DP) coils wound of 6-mm wide and 75- μ m thick REBCO tapes. In order to keep the hoop strains on REBCO tape < 0.6% at an operating current I op of 250 A and in a field of 30.5 T, we overbanded each pancake in Coil 1 with a 6-mm wide, 76- μ m thick 304 stainless steel strip: 7-mm thick radial build for the central 18 pancakes, while 6-mm thick for the outer 2×17 pancakes. In this paper, Coil 1 was successfully tested at 77K and 4.2 K. In the 77-K test, the measured critical current was 35.7 A, determined by an E -field criterion of 0.1 μ V/cm. The center field magnet constant decreased from 34.2 mT/A to 29.3 mT/A, when I op increased from 5 A to 40 A. The field distribution at different I op along the z -axis was measured. The residual field distributions discharged from 10 A and 20 A were recorded. In the 4.2-K test, Coil 1 successfully generated a central field of 8.78 T at 255 A. The magnet constant is 34.4 mT/A, which is same as our designed value. The field homogeneity at the coil center within a ± 15-mm region is around 1700 ppm. This large error field must be reduced before field shimming is applied.

New Side-Looking Rogowski Coil Sensor for Measuring Large-Magnitude Fast Impulse Currents

NASA Astrophysics Data System (ADS)

Metwally, I. A.

2015-12-01

This paper presents a new design of a side-looking "flat spiral" self-integrating Rogowski coil that is wound by twin coaxial cable with individual sheath. The coil is tested with different impulse current waveforms up to 7 kA peak value to improve its performance. The coil design is optimized to achieve bandwidth and sensitivity up to 7.854 MHz and 3.623 V/kA, respectively. The coil is calibrated versus two commercial impulse-current measurement devices at different coil-to-wire separations, coil inclination angles, and impulse current waveforms. Distortion of the coil output voltage waveform is examined by using the lumped-element model to optimize the connections of the four cable winding sheaths and the coil termination resistance. Finally, the coil frequency response is investigated to optimize the coil design parameters and achieve the desired bandwidth (large low-frequency time constant), high rate of rise, no overshoot, very small droop, high rate of fall, and no backswing.

Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a Coil

DTIC Science & Technology

2017-06-14

ARL-MR-0954 ● Jun 2017 US Army Research Laboratory Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a...to Extend and Shield the Magnetic Field of a Coil by W Casey Uhlig Weapons and Materials Research Directorate, ARL...Using Ferromagnetic Material to Extend and Shield the Magnetic Field of a Coil 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER

Second-generation coil design of the Nb 3Sn low-β quadrupole for the high luminosity LHC

DOE PAGES

Bermudez, S. Izquierdo; Ambrosio, G.; Ballarino, A.; ...

2016-01-18

As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build a 150 mm aperture Nb 3Sn quadrupole for the LHC interaction regions. A first series of 1.5 m long coils were fabricated and assembled in a first short model. A detailed visual inspection of the coils was carried out to investigate cable dimensional changes during heat treatment and the position of the windings in the coil straight section and in the end region. The analyses allow identifying a set of design changes which, combined with amore » fine tune of the cable geometry and a field quality optimization, were implemented in a new, second-generation, coil design. In this study, we review the main characteristics of the first generation coils, describe the modification in coil lay-out, and discuss their impact on parts design and magnet analysis.« less

Mechanical strength of an ITER coil insulation system under static and dynamic load after reactor irradiation

NASA Astrophysics Data System (ADS)

Bittner-Rohrhofer, K.; Humer, K.; Weber, H. W.; Hamada, K.; Sugimoto, M.; Okuno, K.

2002-12-01

The insulation system proposed by the Japanese Home Team for the ITER Toroidal Field coil (TF coil) is a T-glass-fiber/Kapton reinforced epoxy prepreg system. In order to assess the material performance under the actual operating conditions of the coils, the insulation system was irradiated in the TRIGA reactor (Vienna) to a fast neutron fluence of 2×10 22 m -2 ( E>0.1 MeV). After measurements of swelling, all mechanical tests were carried out at 77 K. Tensile and short-beam-shear (SBS) tests were performed under static loading conditions. In addition, tension-tension fatigue experiments up to about 10 6 cycles were made. The laminate swells in the through-thickness direction by 0.86% at the highest dose level. The fatigue tests as well as the static tests do not show significant influences of the irradiation on the mechanical behavior of this composite.

Mu2e transport solenoid prototype tests results

DOE PAGES

Lopes, Mauricio L.; G. Ambrosio; DiMarco, J.; ...

2016-02-08

The Fermilab Mu2e experiment has been developed to search for evidence of charged lepton flavor violation through the direct conversion of muons into electrons. The transport solenoid is an s-shaped magnet which guides the muons from the source to the stopping target. It consists of fifty-two superconducting coils arranged in twenty-seven coil modules. A full-size prototype coil module, with all the features of a typical module of the full assembly, was successfully manufactured by a collaboration between INFN-Genoa and Fermilab. The prototype contains two coils that can be powered independently. In order to validate the design, the magnet went throughmore » an extensive test campaign. Warm tests included magnetic measurements with a vibrating stretched wire, electrical and dimensional checks. As a result, the cold performance was evaluated by a series of power tests as well as temperature dependence and minimum quench energy studies.« less

Measuring the orthogonality error of coil systems

USGS Publications Warehouse

Heilig, B.; Csontos, A.; Pajunpää, K.; White, Tim; St. Louis, B.; Calp, D.

2012-01-01

Recently, a simple method was proposed for the determination of pitch angle between two coil axes by means of a total field magnetometer. The method is applicable when the homogeneous volume in the centre of the coil system is large enough to accommodate the total field sensor. Orthogonality of calibration coil systems used for calibrating vector magnetometers can be attained by this procedure. In addition, the method can be easily automated and applied to the calibration of delta inclination–delta declination (dIdD) magnetometers. The method was tested by several independent research groups, having a variety of test equipment, and located at differing geomagnetic observatories, including: Nurmijärvi, Finland; Hermanus, South Africa; Ottawa, Canada; Tihany, Hungary. This paper summarizes the test results, and discusses the advantages and limitations of the method.

Coiled-coil forming peptides for the induction of silver nanoparticles

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

Božič Abram, Sabina; Graduate School of Biomedicine, University of Ljubljana, Ljubljana 1000; Aupič, Jana

Biopolymers with defined sequence patterns offer an attractive alternative for the formation of silver nanoparticle (AgNP). A set of coiled-coil dimer forming peptides was tested for their AgNP formation ability. Seventeen of those peptides mediated the formation of AgNPs in aqueous solution at neutral pH, while the formation of a coiled-coil dimer inhibited the nanoparticle generation. A QSAR regression model on the relationship between sequence and function suggests that in this peptide type the patterns KXQQ and KXEE are favorable, whereas Ala residues appear to have an inhibitory effect. UV–VIS spectra of the obtained nanoparticles gave a peak at aroundmore » 420 nm, typical for AgNPs in the size range around 40 nm, which was confirmed by dynamic light scattering and transmission electron microscopy. Peptide-induced AgNPs exhibited good antibacterial activity, even after a 15 min contact time, while they had low toxicity to human cells at the same concentrations. These results show that our designed peptides generate AgNPs with antibacterial activity at mild conditions and might be used for antibacterial coatings. - Highlights: • 17 of the 30 tested coiled-coil forming peptides induce AgNP formation. • Coiled-coil dimer formation suppresses AgNP generation of individual peptides. • Size of the peptide-induced silver nanoparticles is around 40 nm. • QSAR analysis points to the importance of KXQQ and KXEE motifs for AgNP generation. • Peptide-induced silver nanoparticles exhibit antibacterial activity.« less

Application of mosquito repellent coils and associated self-reported health issues in Ghana.

PubMed

Hogarh, Jonathan N; Antwi-Agyei, Philip; Obiri-Danso, Kwasi

2016-02-04

The use of mosquito coils has gained widespread patronage in malaria-endemic countries, even though it is not a recommended preventive measure for avoiding mosquitoes. Mosquito coils contain insecticides, which are expected to vaporize slowly once the coil is lit, to provide protection against the mosquito. The mosquito coil base material contains a variety of compounds capable of burning slowly to gradually release the insecticide. The mosquito coil smoke, however, is potentially a source of indoor air pollution with implications for acute respiratory infections (ARI) and other illnesses. The present study investigated the application of mosquito coils and associated self-reported health issues in Ghana. A cross-sectional study was undertaken in which questionnaires were randomly administered to 480 households across four districts in Ghana. Respondents who exclusively applied mosquito coils were grouped as test cohort, while those who did not apply any mosquito repellency method constituted a control cohort. The test group that applied mosquito coils reported malaria incidence rate of 86.3 %. The control group that did not apply any mosquito repellency method reported an incidence rate of malaria at 72.4 %. Chi square analysis suggested that the observed difference was statistically significant (x (2) = 4.25; p = 0.04). The number of respondents who reported symptoms of cough from mosquito coil application (52.6 % incidence rate) was marginally greater than their counterparts who did not apply coils (46.1 % incidence rate). It was also found that respondents with shortage of breath, which was used as a proxy for ARI, were more likely to have applied mosquito coil. The application of mosquito coils did not necessarily reduce the incidence of malaria in the study communities. It however presented a potential respiratory risk factor, which should be further investigated by critically examining exposure to particulate matter emissions from burning coils.

Electrical and Quench Performance of the First MICE Coupling Coil

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

Tartaglia, M. A.; Carcagno, R.; Makulski, A.

The first MICE Coupling Coil has been tested in a conduction-cooled environment in the new Solenoid Test Facility at Fermilab. We present an overview of the power and quench protection scheme, and report on the electrical and quench performance results obtained during cold power tests of the magnet.

Electrical and Quench Performance of the First MICE Coupling Coil

DOE PAGES

Tartaglia, M. A.; Carcagno, R.; Makulski, A.; ...

2014-11-10

The first MICE Coupling Coil has been tested in a conduction-cooled environment in the new Solenoid Test Facility at Fermilab. We present an overview of the power and quench protection scheme, and report on the electrical and quench performance results obtained during cold power tests of the magnet.

Coil Opener and Down Ender Operator (iron & steel) 7-88.305; Conveyor Man (iron & steel) 7-88.300; Cooling Conveyor Operator (iron & steel) 7-88.241; Tester Conveyor Operator (iron & steel) 7-88.241; Thread Entry Conveyor Operator (iron & steel) 7-88.241; Yard Transfer Conveyor Operator (iron & steel) 7-88.241--Technical Report on Standardization of the General Aptitude Test Battery.

ERIC Educational Resources Information Center

Manpower Administration (DOL), Washington, DC. U.S. Training and Employment Service.

The United States Training and Employment Service General Aptitude Test Battery (GATB), first published in 1947, has been included in a continuing program of research to validate the tests against success in many different occupations. The GATB consists of 12 tests which measure nine aptitudes: General Learning Ability; Verbal Aptitude; Numerical…

Toroid cavity/coil NMR multi-detector

DOEpatents

Gerald, II, Rex E.; Meadows, Alexander D.; Gregar, Joseph S.; Rathke, Jerome W.

2007-09-18

An analytical device for rapid, non-invasive nuclear magnetic resonance (NMR) spectroscopy of multiple samples using a single spectrometer is provided. A modified toroid cavity/coil detector (TCD), and methods for conducting the simultaneous acquisition of NMR data for multiple samples including a protocol for testing NMR multi-detectors are provided. One embodiment includes a plurality of LC resonant circuits including spatially separated toroid coil inductors, each toroid coil inductor enveloping its corresponding sample volume, and tuned to resonate at a predefined frequency using a variable capacitor. The toroid coil is formed into a loop, where both ends of the toroid coil are brought into coincidence. Another embodiment includes multiple micro Helmholtz coils arranged on a circular perimeter concentric with a central conductor of the toroid cavity.

Effect of Recycling and Autoclave Sterilization on the Unloading Forces of NiTi Closed-Coil Springs: An In Vitro Study.

PubMed

Momeni Danaei, Sh; Oshagh, M; Khozaei, A

2013-12-01

Clinicians use the NiTi coil springs frequently for its appropriate mechanical properties. The aim of this study was to determine the effect of recycling and autoclave sterilization on the unloading forces of NiTi closed coil springs. Fourteen NiTi closed coil spring with the length of 9mm were selected. Each coil was stretched to a peak extension of 12 mm. A universal testing machine was used to acquire load/deflection curve of the coil springs at 25±2°C. The influence of thermocycling (1000 cycles,5-55°C), autoclaving (134°C, 32PSI, 3min) and mechanical strain (9mm extension) which simulated the oral condition, were considered. Data were statistically analyzed by adopting Repeated Measures MANOVA Paired t-Test. Autoclaving in the 1, 4, 6 steps increased the force levels of coil springs about 2-5gf (p< 0.01). Thermocycling reduced their force levels about 4-6gf. Prolonged strain at 3, 5 steps decreased the magnitude of forces levels about 3-4gf. Concerning all the limitations; according to the results of this study; it is possible to recycle Ni-Ti closed-coil springs without significant reduction in their force levels.

Eddy current testing probe with dual half-cylindrical coils

NASA Astrophysics Data System (ADS)

Bae, Byung-Hoon; Choi, Jung-Mi; Kim, Soo-Yong

2000-02-01

We have developed a new eddy current probe composed of a dual half-cylindrical (2HC) coil as an exciting coil and a sensing coil that is placed in the small gap of the 2HC coil. The 2HC coil induces a linear eddy current on the narrow region within the target medium. The magnitude of eddy current has a maximum peak with the narrow width, underneath the center of the exciting 2HC coil. Because of the linear eddy current, the probe can be used to detect not only the existence of a crack but also its direction in conducting materials. Using specimen with a machined crack, and varying the exciting frequency from 0.5 to 100 kHz, we investigated the relationships between the direction of crack and the output voltage of the sensing coil.

Replacement of charged and polar residues in the coiled-coiled interface of huntingtin-interacting protein 1 (HIP1) causes aggregation and cell death.

PubMed

Fontaine, Sarah N; Bauer, Scott P; Lin, Xiaoyan; Poorfarahani, Sara; Ybe, Joel A

2012-09-21

HIP1 crystal structures solved in our laboratory revealed abnormalities in the coiled-coil region, suggesting intrinsic plasticity. To test this, specific amino acids in the coiled-coil were mutated. The apparent thermal stability of HIP1 was altered when Thr528 and Glu531 were replaced by leucine, and was enhanced when Lys510 was also mutated. In cells, HIP1 mutant expression produced aggregation. MTS and flow cytometry indicate a correlation between aggregated HIP1 and enhanced cell death. These data support the idea that flexibility of the HIP1 coiled-coil domain is important for normal function and may lead to new insights into Huntington's disease. Copyright © 2012 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Magnetic analysis of the Nb$$_3$$Sn low-beta quadrupole for the high luminosity LHC

DOE PAGES

Bermudez, Susana Izquierdo; Ambrosio, G.; Chlachidze, G.; ...

2017-01-10

As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build 150 mm aperture Nb 3Sn quadrupoles for the LHC interaction regions. A first series of 1.5 m long coils were fabricated, assembled and tested in the first short model. This paper presents the magnetic analysis, comparing magnetic field measurements with the expectations and the field quality requirements. The analysis is focused on the geometrical harmonics, iron saturation effect and cold-warm correlation. Three dimensional effects such as the variability of the field harmonics along the magnet axismore » and the contribution of the coil ends are also discussed. Furthemore, we present the influence of the conductor magnetization and the dynamic effects.« less

Full-scale locomotive dynamic crash testing and correlations : locomotive consist colliding with steel coil truck at grade crossing (test 3).

DOT National Transportation Integrated Search

2011-09-01

This report presents the test results and finite element correlations of a full-scale dynamic collision between a locomotive and a highway truck loaded with two heavy steel coils. The locomotive consist was moving at 58 miles per hour before it struc...

77 FR 48427 - Airworthiness Directives; Airbus Airplanes

Federal Register 2010, 2011, 2012, 2013, 2014

2012-08-14

... was prompted by a report of a capacitive density condensator (cadensicon) coil overheating during... direct path to the Capacitive Density Condensator (Cadensicon). During tests that were carried out... prompted by a report of a capacitive density condensator (cadensicon) coil overheating during testing. We...

Eddy current inspection tool which is selectively operable in a discontinuity detection mode and a discontinuity magnitude mode

DOEpatents

Petrini, Richard R.; Van Lue, Dorin F.

1983-01-01

A miniaturized inspection tool, for testing and inspection of metal objects in locations with difficult accessibility, which comprises eddy current sensing equipment (12) with a probe coil (11), and associated coaxial coil cable (13), coil energizing means (21), and circuit means (21, 12) 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 17 of fiberoptic scope 10. The scope 10 is provided with light transmitting and receiving fiberoptics for viewing through the flexible tube, and articulation means (19, 20) 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 30 for generating audibly 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.

Eddy current inspection tool which is selectively operable in a discontinuity detection mode and a discontinuity magnitude mode

DOEpatents

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

1983-10-25

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, coil 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 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 30 for generating audibly 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 signaling 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. 5 figs.

''Football'' test coil: a simulated service test of internally-cooled, cabled superconductor

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

Marston, P.G.; Iwasa, Y.; Thome, R.J.

Internally-cooled, cabled superconductor, (ICCS), appears from small-scale tests to be a viable alternative to pool-boiling cooled superconductors for large superconducting magnets. Potential advantages may include savings in helium inventory, smaller structure and ease of fabrication. Questions remain, however, about the structural performance of these systems. The ''football'' test coil has been designed to simulate the actual ''field-current-stress-thermal'' operating conditions of a 25 ka ICCS in a commercial scale MHD magnet. The test procedure will permit demonstration of the 20 year cyclic life of such a magnet in less than 20 days. This paper describes the design, construction and test ofmore » that coil which is wound of copper-stabilized niobium-titanium cable in steel conduit. 2 refs.« less

A superconducting large-angle magnetic suspension

NASA Technical Reports Server (NTRS)

Downer, James R.; Anastas, George V., Jr.; Bushko, Dariusz A.; Flynn, Frederick J.; Goldie, James H.; Gondhalekar, Vijay; Hawkey, Timothy J.; Hockney, Richard L.; Torti, Richard P.

1992-01-01

SatCon Technology Corporation has completed a Small Business Innovation Research (SBIR) Phase 2 program to develop a Superconducting Large-Angle Magnetic Suspension (LAMS) for the NASA Langley Research Center. The Superconducting LAMS was a hardware demonstration of the control technology required to develop an advanced momentum exchange effector. The Phase 2 research was directed toward the demonstration for the key technology required for the advanced concept CMG, the controller. The Phase 2 hardware consists of a superconducting solenoid ('source coils') suspended within an array of nonsuperconducting coils ('control coils'), a five-degree-of-freedom positioning sensing system, switching power amplifiers, and a digital control system. The results demonstrated the feasibility of suspending the source coil. Gimballing (pointing the axis of the source coil) was demonstrated over a limited range. With further development of the rotation sensing system, enhanced angular freedom should be possible.

A superconducting large-angle magnetic suspension

NASA Astrophysics Data System (ADS)

Downer, James R.; Anastas, George V., Jr.; Bushko, Dariusz A.; Flynn, Frederick J.; Goldie, James H.; Gondhalekar, Vijay; Hawkey, Timothy J.; Hockney, Richard L.; Torti, Richard P.

1992-12-01

SatCon Technology Corporation has completed a Small Business Innovation Research (SBIR) Phase 2 program to develop a Superconducting Large-Angle Magnetic Suspension (LAMS) for the NASA Langley Research Center. The Superconducting LAMS was a hardware demonstration of the control technology required to develop an advanced momentum exchange effector. The Phase 2 research was directed toward the demonstration for the key technology required for the advanced concept CMG, the controller. The Phase 2 hardware consists of a superconducting solenoid ('source coils') suspended within an array of nonsuperconducting coils ('control coils'), a five-degree-of-freedom positioning sensing system, switching power amplifiers, and a digital control system. The results demonstrated the feasibility of suspending the source coil. Gimballing (pointing the axis of the source coil) was demonstrated over a limited range. With further development of the rotation sensing system, enhanced angular freedom should be possible.

Peripheral nerve stimulation characteristics of an asymmetric head-only gradient coil compatible with a high-channel-count receiver array.

PubMed

Lee, Seung-Kyun; Mathieu, Jean-Baptiste; Graziani, Dominic; Piel, Joseph; Budesheim, Eric; Fiveland, Eric; Hardy, Christopher J; Tan, Ek Tsoon; Amm, Bruce; Foo, Thomas K-F; Bernstein, Matt A; Huston, John; Shu, Yunhong; Schenck, John F

2016-12-01

To characterize peripheral nerve stimulation (PNS) of an asymmetric head-only gradient coil that is compatible with a commercial high-channel-count receive-only array. Two prototypes of an asymmetric head-only gradient coil set with a 42-cm inner diameter were constructed for brain imaging at 3T with maximum performance specifications of up to 85 mT/m and 708 T/m/s. Tests were performed in 24 volunteers to measure PNS thresholds with the transverse (x = left-right; y = anterior-posterior [A/P]) gradient coils of both prototypes. Fourteen of these 24 volunteers were also tested for the z-gradient PNS in the second prototype and were scanned with high-slew-rate echo planar imaging (EPI) immediately after the PNS tests. For both prototypes, the y-gradient PNS threshold was markedly higher than the x-gradient threshold. The z-gradient threshold was intermediate between those for the x- and y-coils. Of the 24 volunteers, only two experienced y-gradient PNS at 80 mT/m and 500 T/m/s. All volunteers underwent the EPI scan without PNS when the readout direction was set to A/P. Measured PNS characteristics of asymmetric head-only gradient coil prototypes indicate that such coils, especially in the A/P direction, can be used for fast EPI readout in high-performance neuroimaging scans with substantially reduced PNS concerns compared with conventional whole body gradient coils. Magn Reson Med 76:1939-1950, 2016. © 2015 International Society for Magnetic Resonance in Medicine. © 2015 International Society for Magnetic Resonance in Medicine.

10 CFR 429.16 - Central air conditioners and heat pumps.

Code of Federal Regulations, 2013 CFR

2013-01-01

...-system, when combined with a selected evaporator coil (indoor unit) or a set of selected indoor units...-evaporator coil combination selected for tests pursuant to paragraph (a)(2)(i) of this section shall include the evaporator coil that is likely to have the largest volume of retail sales with the particular...

10 CFR 429.16 - Central air conditioners and heat pumps.

Code of Federal Regulations, 2012 CFR

2012-01-01

...-system, when combined with a selected evaporator coil (indoor unit) or a set of selected indoor units...-evaporator coil combination selected for tests pursuant to paragraph (a)(2)(i) of this section shall include the evaporator coil that is likely to have the largest volume of retail sales with the particular...

10 CFR 429.16 - Central air conditioners and heat pumps.

Code of Federal Regulations, 2014 CFR

2014-01-01

...-system, when combined with a selected evaporator coil (indoor unit) or a set of selected indoor units...-evaporator coil combination selected for tests pursuant to paragraph (a)(2)(i) of this section shall include the evaporator coil that is likely to have the largest volume of retail sales with the particular...

Test results of a Nb 3Al/Nb 3Sn subscale magnet for accelerator application

DOE PAGES

Iio, Masami; Xu, Qingjin; Nakamoto, Tatsushi; ...

2015-01-28

The High Energy Accelerator Research Organization (KEK) has been developing a Nb 3Al and Nb 3Sn subscale magnet to establish the technology for a high-field accelerator magnet. The development goals are a feasibility demonstration for a Nb 3Al cable and the technology acquisition of magnet fabrication with Nb 3Al superconductors. KEK developed two double-pancake racetrack coils with Rutherford-type cables composed of 28 Nb 3Al wires processed by rapid heating, quenching, and transformation in collaboration with the National Institute for Materials Science and the Fermi National Accelerator Laboratory. The magnet was fabricated to efficiently generate a high magnetic field in amore » minimum-gap common-coil configuration with two Nb 3Al coils sandwiched between two Nb 3Sn coils produced by the Lawrence Berkeley National Laboratory. A shell-based structure and a “bladder and key” technique have been used for adjusting coil prestress during both the magnet assembly and the cool down. In the first excitation test of the magnet at 4.5 K performed in June 2014, the highest quench current of the Nb 3Sn coil, i.e., 9667 A, was reached at 40 A/s corresponding to 9.0 T in the Nb 3Sn coil and 8.2 T in the Nb 3Al coil. The quench characteristics of the magnet were studied.« less

Manufacturing and test of 2G-HTS coils for rotating machines: Challenges, conductor requirements, realization

NASA Astrophysics Data System (ADS)

Oomen, Marijn; Herkert, Werner; Bayer, Dietmar; Kummeth, Peter; Nick, Wolfgang; Arndt, Tabea

2012-11-01

We investigate the use of 2nd-generation High-Temperature Superconductors (2G-HTSs) in the rotors of electrical motors and generators. For these devices the conductor must be wound into robust impregnated coils, which are operated in vacuum at temperatures around 30 K, in strong magnetic fields of about 2T. Differences in thermal contraction between the coil former, conductor constituents, impregnation resin, bandage and heat-sink materials (assembled at room temperature) cause mechanical stresses at operating temperature. Rotating-machine operation adds Lorentz forces and challenging centripetal accelerations up to thousands of g. Second generation-HTS conductors withstand large tensile stresses in axial direction and compression in normal direction. However, shear stresses, axial compression, and tension normal to the conductor can cause degradation in superconducting properties. Such stresses can be mitigated by correct choice of materials, coil lay-out and manufacturing process. A certain stress level will remain, which the conductor must withstand. We have manufactured many impregnated round and race-track coils, using different 2G-HTS conductors, and tested them at temperatures from 25 K to 77 K. Degradation of the superconductor in early coils was traced to the mentioned differences in thermal contraction, and was completely avoided in coils produced later. We will discuss appropriate coil-winding techniques to assure robust and reliable superconductor performance.

Recent progress and tests of radiation resistant impregnation materials for Nb3Sn coils

NASA Astrophysics Data System (ADS)

Bossert, R.; Krave, S.; Ambrosio, G.; Andreev, N.; Chlachidze, G.; Nobrega, A.; Novitski, I.; Yu, M.; Zlobin, A. V.

2014-01-01

Fermilab is collaborating with Lawrence Berkeley National Laboratory (LBNL) and Brookhaven National Laboratory (BNL) (US-LARP collaboration) to develop a large-aperture Nb3Sn superconducting quadrupole for the Large Hadron Collider (LHC) luminosity upgrade. An important component of this work is the development of materials that are sufficiently radiation resistant for use in critical areas of the upgrade. This paper describes recent progress in characterization of materials, including the baseline CTD101K epoxy, cyanate ester blends, and Matrimid 5292, a bismaleimide-based system. Structural properties of "ten stacks" of cable impregnated with these materials are tested at room and cryogenic temperatures and compared to the baseline CT-101K. Experience with potting 1 and 2 meter long coils with Matrimid 5292 are described. Test results of a single 1-m coil impregnated with Matrimid 5292 are reported and compared to similar coils impregnated with the traditional epoxy.

A 5.9 tesla conduction-cooled coil composed of a stack of four single pancakes wound with YBCO wide tapes

NASA Astrophysics Data System (ADS)

Iwai, Sadanori; Miyazaki, Hiroshi; Tosaka, Taizo; Tasaki, Kenji; Urata, Masami; Ioka, Shigeru; Ishii, Yusuke

2013-11-01

We have been developing a conduction-cooled coil wound with YBCO-coated conductors for HTS applications. Previously, we have fabricated a coil composed of a stack of 12 single pancakes wound with 4 mm-wide YBCO tapes. This coil had a central magnetic field as high as 5.1 T at 10 K under conduction-cooled conditions. In the present study, we fabricated and tested a coil composed of a stack of four single pancakes wound with 12 mm-wide YBCO tapes. The total size of the coil and the Jc value of the tapes were almost the same as those of the former coil. At 77 K, the voltage-current characteristics showed a high n-value of 24, confirming that the coil had no degradation. Furthermore, in a conduction-cooled configuration at 20 K to 60 K, the coil showed a high n-value of over 20. At 20 K, the central magnetic field reached 5.9 T at 903 A, which is 1.3-times higher than that of the former coil.

Utilization trends and clinical outcomes in patients implanted with a single- vs a dual-coil implantable cardioverter-defibrillator lead: Insights from the ALTITUDE Study.

PubMed

Hsu, Jonathan C; Saxon, Leslie A; Jones, Paul W; Wehrenberg, Scott; Marcus, Gregory M

2015-08-01

Historically, the most commonly implanted implantable cardioverter-defibrillator (ICD) lead is dual coil. Conventional wisdom holds that single-coil leads may be less effective than dual-coil leads, but easier to extract. No contemporary large-scale studies have evaluated the relative epidemiology of these 2 leads or compared their respective clinical outcomes. We sought to evaluate trends in single- vs dual-coil ICD lead implantation and differences in clinical outcomes. We evaluated 129,520 ICD recipients enrolled in the LATITUDE remote monitoring system between 2004 and 2014. Kaplan-Meier analyses and Cox proportional hazards regression analyses were used for univariate and multivariate survival analysis, respectively. The majority of ICD recipients received a dual-coil lead (n = 110,330 [85.2%]). Single-coil lead implantation increased from 1.9% to 55.2% between 2004 and 2014. After adjusting for age, sex, device type, and year of implant, single-coil lead implantation was associated with a greater odds of induction for defibrillation testing (odds ratio 1.05; 95% confidence interval [CI] 1.01-1.09; P = .0274), a higher rate of lead being taken out of service (hazard ratio 1.19; 95% CI 1.06-1.33; P = .0032), and a decreased mortality rate (hazard ratio 0.91; 95% CI 0.87-0.96; P = .0004). In a 795 patient subset with adjudicated shock outcomes, first shock success was no different (87.0% in single coil vs 86.1% in dual coil; P = .8473). In a large real-world US population, single-coil lead implantation rates increased substantially between 2004 and 2014. Single-coil lead implantation was associated with more frequent defibrillation testing and the lead being taken out of service, but was not associated with increased mortality or more frequent defibrillation failure. Copyright © 2015 Heart Rhythm Society. All rights reserved.

Design Optimization for a Maglev System Employing Flux Eliminating Coils

NASA Technical Reports Server (NTRS)

Davey, Kent R.

1996-01-01

Flux eliminating coils have received no little attention over the past thirty years as an alternative for realizing lift in a MAGLEV system. When the magnets on board the vehicle are displaced from the equilibrium or null flux point of these coils, they induce current in those coils which act to restore the coil to its null flux or centerline position. The question being addressed in this paper is that of how to choose the best coil for a given system. What appears at first glance to be an innocent question is in fact one that is actually quite involved, encompassing both the global economics and physics of the system. The real key in analyzing that question is to derive an optimization index or functional which represents the cost of the system subject to constraints, the primary constraint being that the vehicle lift itself at a certain threshold speed. Outlined in this paper is one scenario for realizing a total system design which uses sequential quadratic programming techniques.

A multi-slot surface coil for MRI of dual-rat imaging at 4 T

NASA Astrophysics Data System (ADS)

Solis, S. E.; Wang, R.; Tomasi, D.; Rodriguez, A. O.

2011-06-01

A slotted surface coil inspired by the hole-and-slot cavity magnetron was developed for magnetic resonance imaging of obese rats at 4 T. Full-wave analysis of the magnetic field was carried out at 170 MHz for both the slotted and circular-shaped coils. The noise figure values of two coils were investigated via the numerical calculation of the quality factors. Fat simulated phantoms to mimic overweight rats were included in the analysis with weights ranging from 300 to 900 g. The noise figures were 1.2 dB for the slotted coil and 2.4 dB for the circular coil when loaded with 600 g of simulated phantom. A slotted surface coil with eight circular slots and a circular coil with similar dimensions were built and operated in the transceiver mode, and their performances were experimentally compared. The imaging tests in phantoms demonstrated that the slotted surface coil has a deeper RF-sensitivity and better field uniformity than the single-loop RF-coil. High quality images of two overweight Zucker rats were acquired simultaneously with the slotted surface coil using standard spin-echo pulse sequences. Experimental results showed that the slotted surface coil outperformed the circular coil for imaging considerably overweight rats. Thus, the slotted surface coil can be a good tool for MRI experiments in rats on a human whole-body 4 T scanner.

Relevance of Occlusion Test in Endovascular Coiling of Posterior Cerebral Artery (P2 Segment) Aneurysms

PubMed Central

Jayakumar, P. N.; Desai, S.; Srikanth, S. G.; Ravishankar, S.; Kovoor, J. M. E.

2004-01-01

Summary P2 segment aneurysms are located on the posterior cerebral artery (PCA) between the junction of the posterior communicating artery with the PCA and the quadrigeminal cisternal part of the PCA. We reviewed our experience with endovascular coiling in such aneurysms. Clinical and pre-procedural data from four patients, referred for endovascular treatment of P2 segment aneurysms, were retrospectively studied for factors influencing post-interventional neurological deficits caused by ischemia of the PCA distal territory. Balloon occlusion was done in three patients and patient tolerance was assessed using clinical and anatomic criteria. Embryologic and anatomic features of the PCA were reviewed. Balloon occlusion test and endovascular coiling of aneurysms was possible in three patients. Control angiogram after embolization showed elimination of aneurysms from the circulation and the distal PCA filled through leptomeningeal anastomoses. One patient deteriorated due to aneurysmal rupture soon after the balloon occlusion test and coiling could not be done. In the other three patients post-intervention CT and MRI images showed PCA territory infarcts in spite of demonstration of good collateral circulation distal to the occluded PCA. In conclusion, P2 aneurysms can be effectively treated by endovascular coiling without a balloon occlusion test. While the balloon occlusion test does not contribute to clinical decision-making it may be associated with potential morbidity and mortality. PMID:20587236

Impedance of curved rectangular spiral coils around a conductive cylinder

NASA Astrophysics Data System (ADS)

Burke, S. K.; Ditchburn, R. J.; Theodoulidis, T. P.

2008-07-01

Eddy-current induction due to a thin conformable coil wrapped around a long conductive cylinder is examined using a second-order vector potential formalism. Compact closed-form expressions are derived for the self- and mutual impedances of curved rectangular spiral coils (i) in free space and (ii) when wrapped around the surface of the cylindrical rod. The validity of these expressions was tested against the results of a systematic series of experiments using a cylindrical Al-alloy rod and conformable coils manufactured using flexible printed-circuit-board technology. The theoretical expressions were in very good agreement with the experimental measurements. The significance of the results for eddy-current nondestructive inspection using flexible coils and flexible coil arrays is discussed.

The mutual inductance calculation between circular and quadrilateral coils at arbitrary attitudes using a rotation matrix for airborne transient electromagnetic systems

NASA Astrophysics Data System (ADS)

Ji, Yanju; Wang, Hongyuan; Lin, Jun; Guan, Shanshan; Feng, Xue; Li, Suyi

2014-12-01

Performance testing and calibration of airborne transient electromagnetic (ATEM) systems are conducted to obtain the electromagnetic response of ground loops. It is necessary to accurately calculate the mutual inductance between transmitting coils, receiving coils and ground loops to compute the electromagnetic responses. Therefore, based on Neumann's formula and the measured attitudes of the coils, this study deduces the formula for the mutual inductance calculation between circular and quadrilateral coils, circular and circular coils, and quadrilateral and quadrilateral coils using a rotation matrix, and then proposes a method to calculate the mutual inductance between two coils at arbitrary attitudes (roll, pitch, and yaw). Using coil attitude simulated data of an ATEM system, we calculate the mutual inductance of transmitting coils and ground loops at different attitudes, analyze the impact of coil attitudes on mutual inductance, and compare the computational accuracy and speed of the proposed method with those of other methods using the same data. The results show that the relative error of the calculation is smaller and that the speed-up is significant compared to other methods. Moreover, the proposed method is also applicable to the mutual inductance calculation of polygonal and circular coils at arbitrary attitudes and is highly expandable.

Power Loss Analysis and Comparison of Segmented and Unsegmented Energy Coupling Coils for Wireless Energy Transfer

PubMed Central

Tang, Sai Chun; McDannold, Nathan J.

2015-01-01

This paper investigated the power losses of unsegmented and segmented energy coupling coils for wireless energy transfer. Four 30-cm energy coupling coils with different winding separations, conductor cross-sectional areas, and number of turns were developed. The four coils were tested in both unsegmented and segmented configurations. The winding conduction and intrawinding dielectric losses of the coils were evaluated individually based on a well-established lumped circuit model. We found that the intrawinding dielectric loss can be as much as seven times higher than the winding conduction loss at 6.78 MHz when the unsegmented coil is tightly wound. The dielectric loss of an unsegmented coil can be reduced by increasing the winding separation or reducing the number of turns, but the power transfer capability is reduced because of the reduced magnetomotive force. Coil segmentation using resonant capacitors has recently been proposed to significantly reduce the operating voltage of a coil to a safe level in wireless energy transfer for medical implants. Here, we found that it can naturally eliminate the dielectric loss. The coil segmentation method and the power loss analysis used in this paper could be applied to the transmitting, receiving, and resonant coils in two- and four-coil energy transfer systems. PMID:26640745

Power Loss Analysis and Comparison of Segmented and Unsegmented Energy Coupling Coils for Wireless Energy Transfer.

PubMed

Tang, Sai Chun; McDannold, Nathan J

2015-03-01

This paper investigated the power losses of unsegmented and segmented energy coupling coils for wireless energy transfer. Four 30-cm energy coupling coils with different winding separations, conductor cross-sectional areas, and number of turns were developed. The four coils were tested in both unsegmented and segmented configurations. The winding conduction and intrawinding dielectric losses of the coils were evaluated individually based on a well-established lumped circuit model. We found that the intrawinding dielectric loss can be as much as seven times higher than the winding conduction loss at 6.78 MHz when the unsegmented coil is tightly wound. The dielectric loss of an unsegmented coil can be reduced by increasing the winding separation or reducing the number of turns, but the power transfer capability is reduced because of the reduced magnetomotive force. Coil segmentation using resonant capacitors has recently been proposed to significantly reduce the operating voltage of a coil to a safe level in wireless energy transfer for medical implants. Here, we found that it can naturally eliminate the dielectric loss. The coil segmentation method and the power loss analysis used in this paper could be applied to the transmitting, receiving, and resonant coils in two- and four-coil energy transfer systems.

Multiple focused EMAT designs for improved surface breaking defect characterization

NASA Astrophysics Data System (ADS)

Thring, C. B.; Fan, Y.; Edwards, R. S.

2017-02-01

Ultrasonic Rayleigh waves can be employed for the detection of surface breaking defects such as rolling contact fatigue and stress corrosion cracking. Electromagnetic Acoustic Transducers (EMATs) are well suited to this technique as they can directly generate Rayleigh waves within the sample without the requirement for wedges, and they are robust and inexpensive compared to laser ultrasonics. Three different EMAT coil types have been developed, and these are compared to assess their ability to detect and characterize small (down to 0.5 mm depth, 1 mm diameter) surface breaking defects in aluminium. These designs are: a pair of linear meander coils used in a pseudo-pulse-echo mode, a pair of focused meander coils also used in pseudo-pulse-echo mode, and a pair of focused racetrack coils used in pitch-catch mode. The linear meander coils are able to detect most of the defects tested, but have a much lower signal to noise ratio and give limited sizing information. The focused meander coils and the focused racetrack coils can detect all defects tested, but have the advantage that they can also characterize the defect sizes on the sample surface, and have a stronger sensitivity at their focal point. Measurements using all three EMAT designs are presented and compared for high resolution imaging of surface-breaking defects.

Design of catheter radio frequency coils using coaxial transmission line resonators for interventional neurovascular MR imaging.

PubMed

Zhang, Xiaoliang; Martin, Alastair; Jordan, Caroline; Lillaney, Prasheel; Losey, Aaron; Pang, Yong; Hu, Jeffrey; Wilson, Mark; Cooke, Daniel; Hetts, Steven W

2017-04-01

It is technically challenging to design compact yet sensitive miniature catheter radio frequency (RF) coils for endovascular interventional MR imaging. In this work, a new design method for catheter RF coils is proposed based on the coaxial transmission line resonator (TLR) technique. Due to its distributed circuit, the TLR catheter coil does not need any lumped capacitors to support its resonance, which simplifies the practical design and construction and provides a straightforward technique for designing miniature catheter-mounted imaging coils that are appropriate for interventional neurovascular procedures. The outer conductor of the TLR serves as an RF shield, which prevents electromagnetic energy loss, and improves coil Q factors. It also minimizes interaction with surrounding tissues and signal losses along the catheter coil. To investigate the technique, a prototype catheter coil was built using the proposed coaxial TLR technique and evaluated with standard RF testing and measurement methods and MR imaging experiments. Numerical simulation was carried out to assess the RF electromagnetic field behavior of the proposed TLR catheter coil and the conventional lumped-element catheter coil. The proposed TLR catheter coil was successfully tuned to 64 MHz for proton imaging at 1.5 T. B 1 fields were numerically calculated, showing improved magnetic field intensity of the TLR catheter coil over the conventional lumped-element catheter coil. MR images were acquired from a dedicated vascular phantom using the TLR catheter coil and also the system body coil. The TLR catheter coil is able to provide a significant signal-to-noise ratio (SNR) increase (a factor of 200 to 300) over its imaging volume relative to the body coil. Catheter imaging RF coil design using the proposed coaxial TLR technique is feasible and advantageous in endovascular interventional MR imaging applications.

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

Jayakumar, R.; Martovetsky, N.N.; Perfect, S.A.

A glass-polyimide insulation system has been proposed by the US team for use in the Central Solenoid (CS) coil of the international Thermonuclear Experimental Reactor (ITER) machine and it is planned to use this system in the CS model coil inner module. The turn insulation will consist of 2 layers of combined prepreg and Kapton. Each layer is 50% overlapped with a butt wrap of prepreg and an overwrap of S glass. The coil layers will be separated by a glass-resin composite and impregnated in a VPI process. Small scale tests on the various components of the insulation are complete.more » It is planned to fabricate and test the insulation in a 4 x 4 insulated CS conductor array which will include the layer insulation and be vacuum impregnated. The conductor array will be subjected to 20 thermal cycles and 100000 mechanical load cycles in a Liquid Nitrogen environment. These loads are similar to those seen in the CS coil design. The insulation will be electrically tested at several stages during mechanical testing. This paper will describe the array configuration, fabrication: process, instrumentation, testing configuration, and supporting analyses used in selecting the array and test configurations.« less

Mechanical testing and development of the helical field coil joint for the Advanced Toroidal Facility

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

Nelson, B.E.; Bryan, W.E.; Goranson, P.L.

1985-01-01

The helical field (HF) coil set for the Advanced Toroidal Facility (ATF) is an M = 12, l = 2, constant-ratio torsatron winding consisting of 2 coils, each with 14 turns of heavy copper conductor. The coils are divided into 24 identical segments to facilitate fabrication and minimize the assembly schedule. The segments are connected across through-bolted lap joints that must carry up to 124,000 A per turn for 5 s or 62,500 A steady-state. In addition, the joints must carry the high magnetic and thermal loads induced in the conductor and still fit within the basic 140- by 30-mmmore » copper envelope. Extensive testing and development were undertaken to verify and refine the basic joint design. Tests included assembly force and clamping force for various types of misalignment; joint resistance as a function of clamping force; clamp bolt relaxation due to thermal cycling; fatigue testing of full-size, multiturn joint prototypes; and low-cycle fatigue and tensile tests of annealed CDA102 copper. The required performance parameters and actual test results, as well as the final joint configuration, are presented. 2 refs., 9 figs., 4 tabs.« less

Electromagnetic tracking system with reduced distortion using quadratic excitation.

PubMed

Bien, Tomasz; Li, Mengfei; Salah, Zein; Rose, Georg

2014-03-01

Electromagnetic tracking systems, frequently used in minimally invasive surgery, are affected by conductive distorters. The influence of conductive distorters on electromagnetic tracking system accuracy can be reduced through magnetic field modifications. This approach was developed and tested. The voltage induced directly by the emitting coil in the sensing coil without additional influence by the conductive distorter depends on the first derivative of the voltage on the emitting coil. The voltage which is induced indirectly by the emitting coil across the conductive distorter in the sensing coil, however, depends on the second derivative of the voltage on the emitting coil. The electromagnetic tracking system takes advantage of this difference by supplying the emitting coil with a quadratic excitation voltage. The method is adaptive relative to the amount of distortion cause by the conductive distorters. This approach is evaluated with an experimental setup of the electromagnetic tracking system. In vitro testing showed that the maximal error decreased from 10.9 to 3.8 mm when the quadratic voltage was used to excite the emitting coil instead of the sinusoidal voltage. Furthermore, the root mean square error in the proximity of the aluminum disk used as a conductive distorter was reduced from 3.5 to 1.6 mm when the electromagnetic tracking system used the quadratic instead of sinusoidal excitation. Electromagnetic tracking with quadratic excitation is immune to the effects of a conductive distorter, especially compared with sinusoidal excitation of the emitting coil. Quadratic excitation of electromagnetic tracking for computer-assisted surgery is promising for clinical applications.

Eddy current inspection tool. [Patent application

DOEpatents

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.

Investigation on Prototype Superconducting Linear Synchronous Motor (LSM) for 600-km/h Wheel-Type Railway

NASA Astrophysics Data System (ADS)

Eom, Beomyong; Lee, Changhyeong; Kim, Seokho; Lee, Changyoung; Yun, Sangwon

The existing wheel-type high-speed railway with a rotatable motor has a limit of 600 km/h speed. The normal conducting electromagnet has several disadvantages to realize 600 km/h speed. Several disadvantages are the increased space and weight, and the decreased electric efficiency to generate the required high magnetic field. In order to reduce the volume and weight, superconducting electromagnets can be considered for LSM (Linear Synchronous Motor). Prior to the fabrication of the real system, a prototype demo-coil is designed and fabricated using 2G high temperature superconducting wire. The prototype HTS coil is cooled by the conduction using a GM cryocooler. To reduce the heat penetration, thermal design was performed for the current leads, supporting structure and radiation shield considering the thermal stress. The operating temperature and current are 30∼40 K and 100 A. The coil consists of two double pancake coils (N, S pole, respectively) and it is driven on a test rail, which is installed for the test car. This paper describes the design and test results of the prototype HTS LSM system. Thermal characteristics are investigated with additional dummy thermal mass on the coil after turning off the cryocooler.

Manufacture and Quality Control of Insert Coil with Real ITER TF Conductor

DOE PAGES

Ozeki, H.; Isono, T.; Uno, Y.; ...

2016-03-02

JAEA successfully completed the manufacture of the toroidal field (TF) insert coil (TFIC) for a performance test of the ITER TF conductor in the final design in cooperation with Hitachi, Ltd. The TFIC is a single-layer 8.875-turn solenoid coil with 1.44-m diameter. This will be tested for 68-kA current application in a 13-T external magnetic field. TFIC was manufactured in the following order: winding of the TF conductor, lead bending, fabrication of the electrical termination, heat treatment, turn insulation, installation of the coil into the support mandrel structure, vacuum pressure impregnation (VPI), structure assembly, and instrumentation. Here in this presentation,more » manufacture process and quality control status for the TFIC manufacturing are reported.« less

Experiment study on an inductive superconducting fault current limiter using no-insulation coils

NASA Astrophysics Data System (ADS)

Qiu, D.; Li, Z. Y.; Gu, F.; Huang, Z.; Zhao, A.; Hu, D.; Wei, B. G.; Huang, H.; Hong, Z.; Ryu, K.; Jin, Z.

2018-03-01

No-insulation (NI) coil made of 2 G high temperature superconducting (HTS) tapes has been widely used in DC magnet due to its excellent performance of engineering current density, thermal stability and mechanical strength. However, there are few AC power device using NI coil at present. In this paper, the NI coil is firstly applied into inductive superconducting fault current limiter (iSFCL). A two-winding structure air-core iSFCL prototype was fabricated, composed of a primary copper winding and a secondary no-insulation winding using 2 G HTS coated conductors. Firstly, in order to testify the feasibility to use NI coil as the secondary winding, the impedance variation of the prototype at different currents and different cycles was tested. The result shows that the impedance increases rapidly with the current rises. Then the iSFCL prototype was tested in a 40 V rms/ 3.3 kA peak short circuit experiment platform, both of the fault current limiting and recovery property of the iSFCL are discussed.

Development of Mini-pole Superconducting Undulator

NASA Astrophysics Data System (ADS)

Jan, J. C.; Hwang, C. S.; Lin, P. H.; Chang, C. H.; Lin, F. Y.

2007-01-01

A mini-pole superconducting undulator with a 15mm period length (SU15) was developed at the National Synchrotron Radiation Research Center (NSRRC). The coil was wound by a superconducting (SC) NbTi wire with small dimensions and low Cu/SC ratio. The design field strength of SU15 with 158turns/pole was 1.4T at 215A, and the magnet gap was 5.6 mm. Extra trim coils and poles are mounted on the main iron pole. The trim coils directly compensate for the strength error of the peak field. The prototype racetrack iron pole was fabricated via electric discharge machining to produce a complete set of 40-poles. The coil was impregnated by epoxy and wrapped in Kapton to maintain insulation between coil and iron pole. A substitution beam duct was built and assembled with the magnet array and tested in the test Dewar. The conceptual design of bath liquid helium (LHe) cryostat has to tolerate more image current and radiation heating on the beam duct.

Development of Ground Coils with Low Eddy Current Loss by Applying the Compression Molding Method after the Coil Winding

NASA Astrophysics Data System (ADS)

Suzuki, Masao; Aiba, Masayuki; Takahashi, Noriyuki; Ota, Satoru; Okada, Shigenori

In a magnetically levitated transportation (MAGLEV) system, a huge number of ground coils will be required because they must be laid for the whole line. Therefore, stable performance and reduced cost are essential requirements for the ground coil development. On the other hand, because the magnetic field changes when the superconducting magnet passes by, an eddy current will be generated in the conductor of the ground coil and will result in energy loss. The loss not only increases the magnetic resistance for the train running but also brings an increase in the ground coil temperature. Therefore, the reduction of the eddy current loss is extremely important. This study examined ground coils in which both the eddy current loss and temperature increase were small. Furthermore, quantitative comparison for the eddy current loss of various magnet wire samples was performed by bench test. On the basis of the comparison, a round twisted wire having low eddy current loss was selected as an effective ground coil material. In addition, the ground coils were manufactured on trial. A favorable outlook to improve the size accuracy of the winding coil and uneven thickness of molded resin was obtained without reducing the insulation strength between the coil layers by applying a compression molding after winding.

Magnetostatic focal spot correction for x-ray tubes operating in strong magnetic fields using iterative optimization

PubMed Central

Lillaney, Prasheel; Shin, Mihye; Conolly, Steven M.; Fahrig, Rebecca

2012-01-01

Purpose: Combining x-ray fluoroscopy and MR imaging systems for guidance of interventional procedures has become more commonplace. By designing an x-ray tube that is immune to the magnetic fields outside of the MR bore, the two systems can be placed in close proximity to each other. A major obstacle to robust x-ray tube design is correcting for the effects of the magnetic fields on the x-ray tube focal spot. A potential solution is to design active shielding that locally cancels the magnetic fields near the focal spot. Methods: An iterative optimization algorithm is implemented to design resistive active shielding coils that will be placed outside the x-ray tube insert. The optimization procedure attempts to minimize the power consumption of the shielding coils while satisfying magnetic field homogeneity constraints. The algorithm is composed of a linear programming step and a nonlinear programming step that are interleaved with each other. The coil results are verified using a finite element space charge simulation of the electron beam inside the x-ray tube. To alleviate heating concerns an optimized coil solution is derived that includes a neodymium permanent magnet. Any demagnetization of the permanent magnet is calculated prior to solving for the optimized coils. The temperature dynamics of the coil solutions are calculated using a lumped parameter model, which is used to estimate operation times of the coils before temperature failure. Results: For a magnetic field strength of 88 mT, the algorithm solves for coils that consume 588 A/cm2. This specific coil geometry can operate for 15 min continuously before reaching temperature failure. By including a neodymium magnet in the design the current density drops to 337 A/cm2, which increases the operation time to 59 min. Space charge simulations verify that the coil designs are effective, but for oblique x-ray tube geometries there is still distortion of the focal spot shape along with deflections of approximately 3 mm in the radial and circumferential directions on the anode. Conclusions: Active shielding is an attractive solution for correcting the effects of magnetic fields on the x-ray focal spot. If extremely long fluoroscopic exposure times are required, longer operation times can be achieved by including a permanent magnet with the active shielding design. PMID:22957623

MAGNETIC DENSITOMETER

DOEpatents

McCann, J.A.; Jones, R.H.

1961-08-15

A magnetic densitometer for locating defects and metallic inclusions in materials is described. The apparatus consists of two primary coils connected in series opposition and adapted te be placed in inductive relation to the material under test, a source of constant frequency alternating current coupled across the primary coil combination, a pick-up coil disposed in symmetrical inductive relationship with said primary coils, a phase-shifter coupled to the output of the energizing source. The output of the phase-shifter is coupled in series with the pick-up coil. An amplifier is provided selective to the third harmonic of the energizing source frequency. The series combination of the pick-up coil and the phase-shifter output are connected across the input of the amplifier, and an amplitude comparitor is coupled to the output of the amplifier and the energizing source for comparing the instantaneous amplitude of the amplifier output and the instantaneous output of the energizing source and producing an output proportional to the difference in amplitude. A recorder is coupled to the output of the amplitude comparison means to give an indication of the amplitude difference, thereby providing a permanent presentation of the character of the changes in characteristics exhibited by the material under test. (AEC)

A magnetic flux leakage and magnetostrictive guided wave hybrid transducer for detecting bridge cables.

PubMed

Xu, Jiang; Wu, Xinjun; Cheng, Cheng; Ben, Anran

2012-01-01

Condition assessment of cables has gained considerable attention for the bridge safety. A magnetic flux leakage and magnetostrictive guided wave hybrid transducer is provided to inspect bridge cables. The similarities and differences between the two methods are investigated. The hybrid transducer for bridge cables consists of an aluminum framework, climbing modules, embedded magnetizers and a ribbon coil. The static axial magnetic field provided by the magnetizers meets the needs of the magnetic flux leakage testing and the magnetostrictive guided wave testing. The magnetizers also provide the attraction for the climbing modules. In the magnetic flux leakage testing for the free length of cable, the coil induces the axial leakage magnetic field. In the magnetostrictive guided wave testing for the anchorage zone, the coil provides a pulse high power variational magnetic field for generating guided waves; the coil induces the magnetic field variation for receiving guided waves. The experimental results show that the transducer with the corresponding inspection system could be applied to detect the broken wires in the free length and in the anchorage zone of bridge cables.

A Magnetic Flux Leakage and Magnetostrictive Guided Wave Hybrid Transducer for Detecting Bridge Cables

PubMed Central

Xu, Jiang; Wu, Xinjun; Cheng, Cheng; Ben, Anran

2012-01-01

Condition assessment of cables has gained considerable attention for the bridge safety. A magnetic flux leakage and magnetostrictive guided wave hybrid transducer is provided to inspect bridge cables. The similarities and differences between the two methods are investigated. The hybrid transducer for bridge cables consists of an aluminum framework, climbing modules, embedded magnetizers and a ribbon coil. The static axial magnetic field provided by the magnetizers meets the needs of the magnetic flux leakage testing and the magnetostrictive guided wave testing. The magnetizers also provide the attraction for the climbing modules. In the magnetic flux leakage testing for the free length of cable, the coil induces the axial leakage magnetic field. In the magnetostrictive guided wave testing for the anchorage zone, the coil provides a pulse high power variational magnetic field for generating guided waves; the coil induces the magnetic field variation for receiving guided waves. The experimental results show that the transducer with the corresponding inspection system could be applied to detect the broken wires in the free length and in the anchorage zone of bridge cables. PMID:22368483

Magnetic Testing, and Modeling, Simulation and Analysis for Space Applications

NASA Technical Reports Server (NTRS)

Boghosian, Mary; Narvaez, Pablo; Herman, Ray

2012-01-01

The Aerospace Corporation (Aerospace) and Lockheed Martin Space Systems (LMSS) participated with Jet Propulsion Laboratory (JPL) in the implementation of a magnetic cleanliness program of the NASA/JPL JUNO mission. The magnetic cleanliness program was applied from early flight system development up through system level environmental testing. The JUNO magnetic cleanliness program required setting-up a specialized magnetic test facility at Lockheed Martin Space Systems for testing the flight system and a testing program with facility for testing system parts and subsystems at JPL. The magnetic modeling, simulation and analysis capability was set up and performed by Aerospace to provide qualitative and quantitative magnetic assessments of the magnetic parts, components, and subsystems prior to or in lieu of magnetic tests. Because of the sensitive nature of the fields and particles scientific measurements being conducted by the JUNO space mission to Jupiter, the imposition of stringent magnetic control specifications required a magnetic control program to ensure that the spacecraft's science magnetometers and plasma wave search coil were not magnetically contaminated by flight system magnetic interferences. With Aerospace's magnetic modeling, simulation and analysis and JPL's system modeling and testing approach, and LMSS's test support, the project achieved a cost effective approach to achieving a magnetically clean spacecraft. This paper presents lessons learned from the JUNO magnetic testing approach and Aerospace's modeling, simulation and analysis activities used to solve problems such as remnant magnetization, performance of hard and soft magnetic materials within the targeted space system in applied external magnetic fields.

Neuropsychological function after endovascular and neurosurgical treatment of subarachnoid hemorrhage: a systematic review and meta-analysis.

PubMed

Egeto, Peter; Loch Macdonald, R; Ornstein, Tisha J; Schweizer, Tom A

2018-03-01

OBJECTIVE Subarachnoid hemorrhage (SAH) is treated with either surgical clipping or endovascular coiling, though the latter is the preferred treatment method given its more favorable functional outcomes. However, neuropsychological functioning after treatment is rarely taken into account. In this meta-analysis, the authors synthesized relevant data from the literature and compared neuropsychological functioning in patients after coiling and clipping of SAH. They hypothesized that the coiled patients would outperform the clipped patients; that group differences would be greater with higher posterior circulation rupture rates, in older patients, and in more recent publications; that group differences would be smaller with greater rates of middle cerebral artery (MCA) rupture; and that anterior communicating artery (ACoA) rupture rates would not influence effect sizes. METHODS The MEDLINE, Embase, and PsycINFO databases were searched for clinical studies that compared neuropsychological functioning after either endovascular coiling or surgical clipping for SAH. Hedge's g and 95% confidence intervals were calculated using random effects models. Patients who had undergone coiling or clipping were compared on test performance in 8 neuropsychological domains: executive functions, language, attention/processing speed, verbal memory, visual memory, spatial memory, visuospatial functions, and intelligence. Patients were also compared with healthy controls, and meta-regressions were used to explore the relation between effect sizes and publication year, delay between treatment and neuropsychological testing, mean patient age, and rates of posterior circulation, ACoA, and MCA ruptures. RESULTS Thirteen studies with 396 clipped cases, 314 coiled cases, and 169 healthy controls were included in the study. The coil-treated patients outperformed the clip-treated patients on executive function (g = 0.17, 95% CI 0.08-0.25) and language tests (g = 0.23, 95% CI 0.07-0.39), and all patients were impaired relative to healthy controls (g ranged from -0.93 to -0.29). Coiled patients outperformed clipped patients to a greater degree in more recent publications, over longer posttreatment testing delays, and among older patients. Higher rates of posterior circulation and MCA aneurysms were associated with smaller group differences, while ACoA rupture rates did not influence effect sizes. CONCLUSIONS Coiling of SAH may promote superior neuropsychological functioning under certain circumstances and could have applications for the specialized care of SAH patients.

The contactless detection of local normal transitions in superconducting coils by using Poynting’s vector method

NASA Astrophysics Data System (ADS)

Habu, K.; Kaminohara, S.; Kimoto, T.; Kawagoe, A.; Sumiyoshi, F.; Okamoto, H.

2010-11-01

We have developed a new monitoring system to detect an unusual event in the superconducting coils without direct contact on the coils, using Poynting's vector method. In this system, the potential leads and pickup coils are set around the superconducting coils to measure local electric and magnetic fields, respectively. By measuring the sets of magnetic and electric fields, the Poynting's vectors around the coil can be obtained. An unusual event in the coil can be detected as the result of the change of the Poynting's vector. This system has no risk of the voltage breakdown which may happen with the balance voltage method, because there is no need of direct contacts on the coil windings. In a previous paper, we have demonstrated that our system can detect the normal transitions in the Bi-2223 coil without direct contact on the coil windings by using a small test system. For our system to be applied to practical devices, it is necessary for the early detection of an unusual event in the coils to be able to detect local normal transitions in the coils. The signal voltages of the small sensors to measure local magnetic and electric fields are small. Although the increase in signals of the pickup coils is attained easily by an increase in the number of turns of the pickup coils, an increase in the signals of the potential lead is not easily attained. In this paper, a new method to amplify the signal of local electric fields around the coil is proposed. The validity of the method has been confirmed by measuring local electric fields around the Bi-2223 coil.

Simplified Numerical Analysis of ECT Probe - Eddy Current Benchmark Problem 3

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

Sikora, R.; Chady, T.; Gratkowski, S.

2005-04-09

In this paper a third eddy current benchmark problem is considered. The objective of the benchmark is to determine optimal operating frequency and size of the pancake coil designated for testing tubes made of Inconel. It can be achieved by maximization of the change in impedance of the coil due to a flaw. Approximation functions of the probe (coil) characteristic were developed and used in order to reduce number of required calculations. It results in significant speed up of the optimization process. An optimal testing frequency and size of the probe were achieved as a final result of the calculation.

INTERCOMPARISON OF PERFORMANCE OF RF COIL GEOMETRIES FOR HIGH FIELD MOUSE CARDIAC MRI

PubMed Central

Constantinides, Christakis; Angeli, S.; Gkagkarellis, S.; Cofer, G.

2012-01-01

Multi-turn spiral surface coils are constructed in flat and cylindrical arrangements and used for high field (7.1 T) mouse cardiac MRI. Their electrical and imaging performances, based on experimental measurements, simulations, and MRI experiments in free space, and under phantom, and animal loading conditions, are compared with a commercially available birdcage coil. Results show that the four-turn cylindrical spiral coil exhibits improved relative SNR (rSNR) performance to the flat coil counterpart, and compares fairly well with a commercially available birdcage coil. Phantom experiments indicate a 50% improvement in the SNR for penetration depths ≤ 6.1 mm from the coil surface compared to the birdcage coil, and an increased penetration depth at the half-maximum field response of 8 mm in the 4-spiral cylindrical coil case, in contrast to 2.9 mm in the flat 4-turn spiral case. Quantitative comparison of the performance of the two spiral coil geometries in anterior, lateral, inferior, and septal regions of the murine heart yield maximum mean percentage rSNR increases of the order of 27–167% in vivo post-mortem (cylindrical compared to flat coil). The commercially available birdcage outperforms the cylindrical spiral coil in rSNR by a factor of 3–5 times. The comprehensive approach and methodology adopted to accurately design, simulate, implement, and test radiofrequency coils of any geometry and type, under any loading conditions, can be generalized for any application of high field mouse cardiac MRI. PMID:23204945

Quantitative analysis of image quality for acceptance and commissioning of an MRI simulator with a semiautomatic method.

PubMed

Chen, Xinyuan; Dai, Jianrong

2018-05-01

Magnetic Resonance Imaging (MRI) simulation differs from diagnostic MRI in purpose, technical requirements, and implementation. We propose a semiautomatic method for image acceptance and commissioning for the scanner, the radiofrequency (RF) coils, and pulse sequences for an MRI simulator. The ACR MRI accreditation large phantom was used for image quality analysis with seven parameters. Standard ACR sequences with a split head coil were adopted to examine the scanner's basic performance. The performance of simulation RF coils were measured and compared using the standard sequence with different clinical diagnostic coils. We used simulation sequences with simulation coils to test the quality of image and advanced performance of the scanner. Codes and procedures were developed for semiautomatic image quality analysis. When using standard ACR sequences with a split head coil, image quality passed all ACR recommended criteria. The image intensity uniformity with a simulation RF coil decreased about 34% compared with the eight-channel diagnostic head coil, while the other six image quality parameters were acceptable. Those two image quality parameters could be improved to more than 85% by built-in intensity calibration methods. In the simulation sequences test, the contrast resolution was sensitive to the FOV and matrix settings. The geometric distortion of simulation sequences such as T1-weighted and T2-weighted images was well-controlled in the isocenter and 10 cm off-center within a range of ±1% (2 mm). We developed a semiautomatic image quality analysis method for quantitative evaluation of images and commissioning of an MRI simulator. The baseline performances of simulation RF coils and pulse sequences have been established for routine QA. © 2018 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

Design and test of current limiting modules using YBCO-coated conductors

NASA Astrophysics Data System (ADS)

Schmidt, W.; Gamble, B.; Kraemer, H.-P.; Madura, D.; Otto, A.; Romanosky, W.

2010-01-01

Within the cooperation between American Superconductor Corporation (AMSC) and Siemens Corporate Technology we have investigated the fault current limiting performance of YBCO-coated conductors (also called second-generation or 2G HTS wires) stabilized with stainless steel laminates. Design rules for the length and width of the wire depending on utility grid requirements have been established. Bifilar coils have been manufactured and tested with a typical limitation period of 50 ms under stepwise increasing voltage loads to determine the maximum temperature the wires can withstand without degradation. Coils have been assembled into limiter modules demonstrating uniform tripping of the individual coils and recovery within seconds. At present this cooperation is proceeding within a joint project funded by the US Department of Energy (DOE) that encompasses the design, construction and testing of a 115 kV FCL for power transmission within a time frame of 4-5 years, and additional partners. Besides AMSC and Siemens, Nexans contributes the high voltage terminations and Los Alamos National Lab investigates the ac losses. Installation and testing are planned for a Southern California Edison substation. The module planned for the transmission voltage application consists of 63 horizontally arranged coils connected in parallel and series to account for a rated current of 1.2 kArms and voltage of 31 kVrms plus margins. The rated voltage of the module is considerably lower than the line to ground voltage in the 115 kV grid owing to our shunted limiter concept. The shunt reactor connected in parallel to the module outside the cryostat allows for adjustment of the limited current and reduces voltage drop across the module in case of a fault. The fault current reduction ratio is 42% for our present design. A subscale module comprising six full-size coils has been assembled and tested recently to validate the coil performance and coil winding technique. The module had a critical current of 425 ADC and a nominal power of 2.52 MV A at 77 K. A complete series of tests with applied voltage up to 8.4 kVrms, prospective short circuit current up to 26.6 kArms and variation of phase angle at initiation of the fault has been performed. After more than 40 switching tests the critical current of the module remained unchanged, indicating that no degradation of the wire occurred.

Electromagnetic interference with cardiac pacemakers and implantable cardioverter-defibrillators from low-frequency electromagnetic fields in vivo.

PubMed

Tiikkaja, Maria; Aro, Aapo L; Alanko, Tommi; Lindholm, Harri; Sistonen, Heli; Hartikainen, Juha E K; Toivonen, Lauri; Juutilainen, Jukka; Hietanen, Maila

2013-03-01

Electromagnetic interference (EMI) can pose a danger to workers with pacemakers and implantable cardioverter-defibrillators (ICDs). At some workplaces electromagnetic fields are high enough to potentially inflict EMI. The purpose of this in vivo study was to evaluate the susceptibility of pacemakers and ICDs to external electromagnetic fields. Eleven volunteers with a pacemaker and 13 with an ICD were exposed to sine, pulse, ramp, and square waveform magnetic fields with frequencies of 2-200 Hz using Helmholtz coil. The magnetic field flux densities varied to 300 µT. We also tested the occurrence of EMI from an electronic article surveillance (EAS) gate, an induction cooktop, and a metal inert gas (MIG) welding machine. All pacemakers were tested with bipolar settings and three of them also with unipolar sensing configurations. None of the bipolar pacemakers or ICDs tested experienced interference in any of the exposure situations. The three pacemakers with unipolar settings were affected by the highest fields of the Helmholtz coil, and one of them also by the EAS gate and the welding cable. The induction cooktop did not interfere with any of the unipolarly programmed pacemakers. Magnetic fields with intensities as high as those used in this study are rare even in industrial working environments. In most cases, employees can return to work after implantation of a bipolar pacemaker or an ICD, after an appropriate risk assessment. Pacemakers programmed to unipolar configurations can cause danger to their users in environments with high electromagnetic fields, and should be avoided, if possible.

Amplatzer Vascular Plugs Versus Coils for Embolization of Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia.

PubMed

Tau, Noam; Atar, Eliyahu; Mei-Zahav, Meir; Bachar, Gil N; Dagan, Tamir; Birk, Einat; Bruckheimer, Elchanan

2016-08-01

Coil embolization of pulmonary arteriovenous malformations (PAVMs) has a high re-canalization/re-perfusion rate. Embolization with Amplatzer plugs has been previously described, but the long-term efficacy is not established. This study reports the experience of a referral medical center with the use of coils and Amplatzer plugs for treating PAVMs in patients with hereditary hemorrhagic telangiectasia. The study was approved by the Institutional Review Board with waiver of informed consent. The cohort included all patients who underwent PAVM embolization in 2004-2014 for whom follow-up imaging scans were available. The medical files were retrospectively reviewed for background data, embolization method (coils, Amplatzer plugs, both), and complications. Re-canalization of treated PAVMs was assessed from intrapulmonary angiograms (following percutaneous procedures) or computed tomography angiograms. Fisher's exact test and Pearson Chi-squared test or t test were used for statistical analysis, with significance at p < 0.05. 16 patients met the study criteria. Imaging scans were available for 63 of the total 110 PAVMs treated in 41 procedures. Coils were used for embolization in 37 PAVMs, Amplatzer plugs in 21, and both in five. Median follow-up time was 7.7 years (range 1.4-18.9). Re-canalization was detected in seven vessels, all treated with coils; there were no cases of re-canalization in plug-occluded vessels (p = 0.0413). The use of Amplatzer plugs for the embolization of PAVMs in patients with hemorrhagic telangiectasia is associated with a significantly lower rate of re-canalization of feeding vessels than coils. Long-term prospective studies are required to confirm these findings.

Amplatzer Vascular Plugs Versus Coils for Embolization of Pulmonary Arteriovenous Malformations in Patients with Hereditary Hemorrhagic Telangiectasia

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

Tau, Noam, E-mail: taunoam@gmail.com; Atar, Eliyahu; Mei-Zahav, Meir

PurposeCoil embolization of pulmonary arteriovenous malformations (PAVMs) has a high re-canalization/re-perfusion rate. Embolization with Amplatzer plugs has been previously described, but the long-term efficacy is not established. This study reports the experience of a referral medical center with the use of coils and Amplatzer plugs for treating PAVMs in patients with hereditary hemorrhagic telangiectasia.MethodsThe study was approved by the Institutional Review Board with waiver of informed consent. The cohort included all patients who underwent PAVM embolization in 2004–2014 for whom follow-up imaging scans were available. The medical files were retrospectively reviewed for background data, embolization method (coils, Amplatzer plugs, both),more » and complications. Re-canalization of treated PAVMs was assessed from intrapulmonary angiograms (following percutaneous procedures) or computed tomography angiograms. Fisher’s exact test and Pearson Chi-squared test or t test were used for statistical analysis, with significance at p < 0.05.Results16 patients met the study criteria. Imaging scans were available for 63 of the total 110 PAVMs treated in 41 procedures. Coils were used for embolization in 37 PAVMs, Amplatzer plugs in 21, and both in five. Median follow-up time was 7.7 years (range 1.4–18.9). Re-canalization was detected in seven vessels, all treated with coils; there were no cases of re-canalization in plug-occluded vessels (p = 0.0413).ConclusionThe use of Amplatzer plugs for the embolization of PAVMs in patients with hemorrhagic telangiectasia is associated with a significantly lower rate of re-canalization of feeding vessels than coils. Long-term prospective studies are required to confirm these findings.« less

Radiation exposure, and procedure and fluoroscopy times in endovascular treatment of intracranial aneurysms: a methodological comparison.

PubMed

Cheung, Nicholas K; Boutchard, Michelle; Carr, Michael W; Froelich, Jens J

2018-01-09

Limited data are available for radiation exposure, and procedure and fluoroscopy times in neuroendovascular treatment (NET) strategies. This study establishes and compares related parameters between coil embolization (COIL), balloon assisted coil embolization (BAC), stent assisted coil embolization (SAC), and flow diverting technology (FDT) in NET of intracranial aneurysms. Between 2010 and 2017, 249 consecutive intracranial aneurysms underwent NET at a single center, all performed by the same operator. Dose area products (DAP), and procedure and fluoroscopy times were recorded and compared between COIL, BAC, SAC, and FDT techniques. Differences in parameters between cohorts were analyzed for significance using the Mann-Whitney U test, unpaired t test and χ 2 test. Additional subgroup analysis was performed for emergency and elective cases. 83 aneurysms were treated with COIL (33%), 72 with BAC (29%), 61 with SAC (25%), and 33 with FDT (13%). Baseline characteristics were largely similar within these groups (P>0.05). Among COIL, BAC, and FDT cohorts, no significant difference was found for mean DAP, or procedure and fluoroscopy times (P>0.05). However, compared with all other cohorts, SAC was associated with a significantly higher DAP and longer procedure and fluoroscopy times (P<0.005). No significant difference was recorded for emergency and elective case subgroups. Compared with other NET strategies, SAC was associated with a significantly higher DAP, and longer procedure and fluoroscopy times. This study provides an initial dataset regarding radiation exposure, and procedure and fluoroscopy times for common NET, and may assist ALARA (As Low As Reasonably Achievable) principles to reduce radiation risks. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Automatic tuned MRI RF coil for multinuclear imaging of small animals at 3T.

PubMed

Muftuler, L Tugan; Gulsen, Gultekin; Sezen, Kumsal D; Nalcioglu, Orhan

2002-03-01

We have developed an MRI RF coil whose tuning can be adjusted automatically between 120 and 128 MHz for sequential spectroscopic imaging of hydrogen and fluorine nuclei at field strength 3 T. Variable capacitance (varactor) diodes were placed on each rung of an eight-leg low-pass birdcage coil to change the tuning frequency of the coil. The diode junction capacitance can be controlled by the amount of applied reverse bias voltage. Impedance matching was also done automatically by another pair of varactor diodes to obtain the maximum SNR at each frequency. The same bias voltage was applied to the tuning varactors on all rungs to avoid perturbations in the coil. A network analyzer was used to monitor matching and tuning of the coil. A Pentium PC controlled the analyzer through the GPIB bus. A code written in LABVIEW was used to communicate with the network analyzer and adjust the bias voltages of the varactors via D/A converters. Serially programmed D/A converter devices were used to apply the bias voltages to the varactors. Isolation amplifiers were used together with RF choke inductors to provide isolation between the RF coil and the DC bias lines. We acquired proton and fluorine images sequentially from a multicompartment phantom using the designed coil. Good matching and tuning were obtained at both resonance frequencies. The tuning and matching of the coil were changed from one resonance frequency to the other within 60 s. (c) 2002 Elsevier Science (USA).

Radio-frequency coil selection for MR imaging of the carotid vessel wall

NASA Astrophysics Data System (ADS)

Mat Isa, S.; Shuaib, I. L.; Bauk, S.

2014-11-01

This aim of this study was to identify the radiofrequency coil that will produce optimum image quality for scanning the carotid vessel wall using magnetic resonance imaging. A comparative cross-sectional study was conducted using 10 volunteers. Each volunteer was scanned three times using a 1.5T Signa HDxt machine equipped with one of three different coils: a neurovascular array (NV) coil, an 8-channel CTL spine array coil, and a 3-inch surface coil. A qualitative image quality rating was assigned to each image. The images were also evaluated by measuring the signal to noise ratio (SNR) using Osirix 4.2.3 software. The noise was estimated from the mean intensities of the region of interest in the background of the images and the signal was measured in the muscle adjacent to the vessel wall. The SNRs of the three coils were compared using one-way ANOVA, with 104 images used for the data analysis. The mean image quality scores for the NV head coil, CTL coil, and 3-inch coil were 3.4, 3.33, and 1.67, respectively. In addition, the SNRs differed significantly (p < 0.05). The mean SNR for the 3-inch coil was significantly higher (56.21 ± 25.06) than those for the NV head coil (27.34 ± 15.47) and CTL coil (21.77 ± 13.14). The Bonferroni post-hoc test revealed that there was no significant difference between the NV head coil and the CTL coil (p = 0.21). The optimum SNR value was 20-27. These results indicate that the NV head coil and CTL coil can be used to evaluate the carotid arterial wall with optimum image quality and higher resolution. These coil can deliver fast and robust data to image the carotid vessel wall in vivo.

Brain GABA Detection in vivo with the J-editing 1H MRS Technique: A Comprehensive Methodological Evaluation of Sensitivity Enhancement, Macromolecule Contamination and Test-Retest Reliability

PubMed Central

Shungu, Dikoma C.; Mao, Xiangling; Gonzales, Robyn; Soones, Tacara N.; Dyke, Jonathan P.; van der Veen, Jan Willem; Kegeles, Lawrence S.

2016-01-01

Abnormalities in brain γ-aminobutyric acid (GABA) have been implicated in various neuropsychiatric and neurological disorders. However, in vivo GABA detection by proton magnetic resonance spectroscopy (1H MRS) presents significant challenges arising from low brain concentration, overlap by much stronger resonances, and contamination by mobile macromolecule (MM) signals. This study addresses these impediments to reliable brain GABA detection with the J-editing difference technique on a 3T MR system in healthy human subjects by (a) assessing the sensitivity gains attainable with an 8-channel phased-array head coil, (b) determining the magnitude and anatomic variation of the contamination of GABA by MM, and (c) estimating the test-retest reliability of measuring GABA with this method. Sensitivity gains and test-retest reliability were examined in the dorsolateral prefrontal cortex (DLPFC), while MM levels were compared across three cortical regions: the DLPFC, the medial prefrontal cortex (MPFC) and the occipital cortex (OCC). A 3-fold higher GABA detection sensitivity was attained with the 8-channel head coil compared to the standard single-channel head coil in DLPFC. Despite significant anatomic variation in GABA+MM and MM across the three brain regions (p < 0.05), the contribution of MM to GABA+MM was relatively stable across the three voxels, ranging from 41% to 49%, a non-significant regional variation (p = 0.58). The test-retest reliability of GABA measurement, expressed either as ratios to voxel tissue water (W) or total creatine, was found to be very high for both the single-channel coil and the 8-channel phased-array coil. For the 8-channel coil, for example, Pearson’s correlation coefficient of test vs. retest for GABA/W was 0.98 (R2 = 0.96, p = 0.0007), the percent coefficient of variation (CV) was 1.25%, and the intraclass correlation coefficient (ICC) was 0.98. Similar reliability was also found for the co-edited resonance of combined glutamate and glutamine (Glx) for both coils. PMID:27173449

Present Status of the KSTAR Superconducting Magnet System Development

NASA Astrophysics Data System (ADS)

Kim, Keeman; H, K. Park; K, R. Park; B, S. Lim; S, I. Lee; M, K. Kim; Y, Chu; W, H. Chung; S, H. Baek; J Y, Choi; H, Yonekawa; A, Chertovskikh; Y, B. Chang; J, S. Kim; C, S. Kim; D, J. Kim; N, H. Song; K, P. Kim; Y, J. Song; I, S. Woo; W, S. Han; D, K. Lee; Y, K. Oh; K, W. Cho; J, S. Park; G, S. Lee; H, J. Lee; T, K. Ko; S, J. Lee

2004-10-01

The mission of Korea Superconducting Tokamak Advanced Research (KSTAR) project is to develop an advanced steady-state superconducting tokamak for establishing a scientific and technological basis for an attractive fusion reactor. Because one of the KSTAR mission is to achieve a steady-state operation, the use of superconducting coils is an obvious choice for the magnet system. The KSTAR superconducting magnet system consists of 16 Toroidal Field (TF) coils and 14 Poloidal Field (PF) coils. Internally-cooled Cable-In-Conduit Conductors (CICC) are put into use in both the TF and PF coil systems. The TF coil system provides a field of 3.5 T at the plasma center and the PF coil system is able to provide a flux swing of 17 V-sec. The major achievement in KSTAR magnet-system development includes the development of CICC, the development of a full-size TF model coil, the development of a coil system for background magnetic-field generation, the construction of a large-scale superconducting magnet and CICC test facility. TF and PF coils are in the stage of fabrication to pave the way for the scheduled completion of KSTAR by the end of 2006.

[Verification of a decrease in the rigidity of the phage lambda DNA polymeric chain in low ionic strength aqueous solutions by testing the polymer-polymer interlink interactions].

PubMed

Arutiunian, A V; Ivanova, M A; Kurliand, D I; Kapshin, Iu S; Landa, S B; Poshekhonov, S T; Drobchenko, E A; Shevelev, I V

2011-01-01

Changes in the rigidity of the polymetric chain of phage lambda double-strand DNA have been studied by laser correlation spectroscopy. It was shown that, as the ionic strength increases, the effect of the screening of the hydrodynamic interaction of the links of the polymeric chain specific for polymeric coils arises in a DNA solution. It is assumed that the screening occurs when the threshold of the overlapping of DNA coils is achieved. The overlapping of coils is the result of a previously observed significant rise of DNA coil size from abnormally small DNA coils in low ionic strength buffers (about 10(-2) M Na+ or less) to maximum possible large coils in the 5SSC and 5SSC-like buffers. Further analysis of the far interlink interactions in linear lambda phage DNA coils in similar buffers at pH 7 and 4 confirms the earlier proposal about the role of H+ ions in the appearance of abnormally small DNA coils. The abnormal decrease in the DNA coil size in low ionic strength buffers is not a specific feature of lambda phage DNA only.

Impact of coil design on the contrast-to-noise ratio, precision, and consistency of quantitative cartilage morphometry at 3 Tesla: a pilot study for the osteoarthritis initiative.

PubMed

Eckstein, Felix; Kunz, Manuela; Hudelmaier, Martin; Jackson, Rebecca; Yu, Joseph; Eaton, Charles B; Schneider, Erika

2007-02-01

Phased-array (PA) coils generally provide higher signal-to-noise ratios (SNRs) than quadrature knee coils. In this pilot study for the Osteoarthritis Initiative (OAI) we compared these two types of coils in terms of contrast-to-noise ratio (CNR), precision, and consistency of quantitative femorotibial cartilage measurements. Test-retest measurements were acquired using coronal fast low-angle shot with water excitation (FLASHwe) and coronal multiplanar reconstruction (MPR) of sagittal double-echo steady state with water excitation (DESSwe) at 3T. The precision errors for cartilage volume and thickness were

Wind and React MgB2 Rotor Coils

NASA Astrophysics Data System (ADS)

Bohnenstiehl, S. D.; Sumption, M. D.; Majoros, M.; Tomsic, M.; Rindfleisch, M.; Phillips, J.; Yue, J.; Collings, E. W.

2008-03-01

Five rotor coils (four plus a spare) intended for a prototype 2 MW generator were fabricated and tested. For each coil, multifilamentary MgB2 strand was wound around a stepped former in a wind and react mode using S-glass insulation in combination with vacuum epoxy impregnation. The stepped, ellipsoidal coils had maximum in-plane dimensions of 26.7 cm×13.1 cm and a total thickness of 5.4 cm, and were wound with approximately 580 m of MgB2 strand per coil. Each of the coils were measured separately for Ic and magnetic field in the bore at 4.2 K and for one coil Ic and B were also measured as a function of temperature. The bore field as a function of position along the z-axis was also determined near the critical current at 4.2 K. The coils typically reached 186 A at 4.2 K generating a 1.7 T field, while at 20 K the Ic was 117 A with a bore field of 1.1 T field.

A 128-channel receive-only cardiac coil for highly accelerated cardiac MRI at 3 Tesla.

PubMed

Schmitt, Melanie; Potthast, Andreas; Sosnovik, David E; Polimeni, Jonathan R; Wiggins, Graham C; Triantafyllou, Christina; Wald, Lawrence L

2008-06-01

A 128-channel receive-only array coil is described and tested for cardiac imaging at 3T. The coil is closely contoured to the body with a "clam-shell" geometry with 68 posterior and 60 anterior elements, each 75 mm in diameter, and arranged in a continuous overlapped array of hexagonal symmetry to minimize nearest neighbor coupling. Signal-to-noise ratio (SNR) and noise amplification for parallel imaging (G-factor) were evaluated in phantom and volunteer experiments. These results were compared to those of commercially available 24-channel and 32-channel coils in routine use for cardiac imaging. The in vivo measurements with the 128-channel coil resulted in SNR gains compared to the 24-channel coil (up to 2.2-fold in the apex). The 128- and 32-channel coils showed similar SNR in the heart, likely dominated by the similar element diameters of these coils. The maximum G-factor values were up to seven times better for a seven-fold acceleration factor (R=7) compared to the 24-channel coil and up to two-fold improved compared to the 32-channel coil. The ability of the 128-channel coil to facilitate highly accelerated cardiac imaging was demonstrated in four volunteers using acceleration factors up to seven-fold (R=7) in a single spatial dimension. Copyright (c) 2008 Wiley-Liss, Inc.

Diagnostics Development for the Ignition Experiment Ignitor

NASA Astrophysics Data System (ADS)

Pizzicaroli, G.; Bombarda, F.; Licciulli, A.; Fersini, M.; Diso, D.; Kroegler, H.

2008-11-01

The Ignitor experiment is designed to reach ignition conditions. The short, but intense neutron flux will pose challenging conditions for diagnostics, such as magnetic sensors or bolometers, in direct proximity, or in direct view, of the plasma. An R&D program is in progress to manufacture mineral insulated magnetic coils with a reduced sensitivity to radiation effects. A double layer, MgO insulated Ni coil has been produced and tested. The wire is wound on an alumina core and the coil is housed in an alumina box for high refractoriness and minimum vacuum degassing. A lanthanide glass ceramic has been used as sealant for the box. At the same time, alternative methods to provide critical plasma position information during the high performance discharges in Ignitor are being explored. For example, the radiation emitted at the plasma edge by Mo^+14 can be monitored by means of a soft X- ray spectrometer equipped with a GEM detector, which allows high counting rates (> 1 MHz) and provides good energy resolution and flexibility of design. A 10x10 cm^2 multichannel prototype with its associated fast read-out system is being assembled. A layout of the complete spectrometer compatible with the Ignitor port design has been carried out, and the bolometer system design has been updated.

Tx/Rx Head Coil Induces Less RF Transmit-Related Heating than Body Coil in Conductive Metallic Objects Outside the Active Area of the Head Coil

PubMed Central

Nagy, Zoltan; Oliver-Taylor, Aaron; Kuehne, Andre; Goluch, Sigrun; Weiskopf, Nikolaus

2017-01-01

The transmit–receive (Tx/Rx) birdcage head coil is often used for excitation instead of the body coil because of the presumably lower risk of heating in and around conductive implants. However, this common practice has not been systematically tested. To investigate whether the Tx/Rx birdcage head coil produces less heating than the body coil when scanning individuals with implants, we used a 3T clinical scanner and made temperature measurements around a straight 15 cm conductor using either the Tx/Rx body or the head coil for excitation. Additionally, the transmitted fields of a Tx/Rx head coil were measured both in air and in gel using a resonant and a non-resonant B field probes as well as a non-resonant E field probe. Simulations using a finite-difference time domain solver were compared with the experimental findings. When the body coil was used for excitation, we observed heating around the 15 cm wire at various anatomical locations (both within and outside of the active volume of the head coil). Outside its active area, no such heating was observed while using the Tx/Rx head coil for excitation. The E and B fields of the Tx/Rx birdcage head coil extended well-beyond the physical dimensions of the coil. In air, the fields were monotonically decreasing, while in gel they were more complex with local maxima at the end of the ASTM phantom. These experimental findings were line with the simulations. While caution must always be exercised when scanning individuals with metallic implants, these findings support the use of the Tx/Rx birdcage head coil in place of the body coil at 3T in order to reduce the risk of heating in and around conductive implants that are remote from the head coil. PMID:28184184

Force delivery of Ni-Ti coil springs.

PubMed

Manhartsberger, C; Seidenbusch, W

1996-01-01

Sentalloy springs (GAC, Central Islip, N.Y.) of the open and closed type were investigated with a special designed device. The closed coil springs were subjected to a tensile and the open coil springs to a compression test. After a first measurement, the springs were activated for a period of 4 weeks and then reinvestigated with the same procedure. It could be shown distinctly that, with the different coil springs, the force delivery given by the producer could be achieved only within certain limits. To remain in the martensitic plateau, changed activation ranges, and for the Sentalloy coil springs white and red of the open and closed type, also changed force deliveries had to be taken into account. There was a distinct decrease in force delivery between the first and second measurement. After considering the loading curves of all the Sentalloy coil springs and choosing the right activation range respective to the force delivery, it was found that the coil springs deliver a superior clinical behavior and open new treatment possibilities.

Design and testing of a coil-unit barrel for helical coil electromagnetic launcher

NASA Astrophysics Data System (ADS)

Yang, Dong; Liu, Zhenxiang; Shu, Ting; Yang, Lijia; Ouyang, Jianming

2018-01-01

A coil-unit barrel for a helical coil electromagnetic launcher is described. It provides better features of high structural strength and flexible adjustability. It is convenient to replace the damaged coil units and easy to adjust the number of turns in the stator coils due to the modular design. In our experiments, the highest velocity measured for a 4.5-kg projectile is 47.3 m/s and the mechanical reinforcement of the launcher could bear 35 kA peak current. The relationship between the energy conversion efficiency and the inductance gradient of the launcher is also studied. In the region of low inductance gradient, the efficiency is positively correlated with the inductance gradient. However, in the region of high inductance gradient, the inter-turn arc erosion becomes a major problem of limiting the efficiency and velocity of the launcher. This modular barrel allows further studies in the inter-turn arc and the variable inductance gradient helical coil launcher.

Design and testing of a coil-unit barrel for helical coil electromagnetic launcher.

PubMed

Yang, Dong; Liu, Zhenxiang; Shu, Ting; Yang, Lijia; Ouyang, Jianming

2018-01-01

A coil-unit barrel for a helical coil electromagnetic launcher is described. It provides better features of high structural strength and flexible adjustability. It is convenient to replace the damaged coil units and easy to adjust the number of turns in the stator coils due to the modular design. In our experiments, the highest velocity measured for a 4.5-kg projectile is 47.3 m/s and the mechanical reinforcement of the launcher could bear 35 kA peak current. The relationship between the energy conversion efficiency and the inductance gradient of the launcher is also studied. In the region of low inductance gradient, the efficiency is positively correlated with the inductance gradient. However, in the region of high inductance gradient, the inter-turn arc erosion becomes a major problem of limiting the efficiency and velocity of the launcher. This modular barrel allows further studies in the inter-turn arc and the variable inductance gradient helical coil launcher.

Magnetic shielding of interplanetary spacecraft against solar flare radiation

NASA Technical Reports Server (NTRS)

Cocks, Franklin H.; Watkins, Seth

1993-01-01

The ultimate objective of this work is to design, build, and fly a dual-purpose, piggyback payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field (1) to protect spacecraft against solar flare protons, (2) to produce a thrust of sufficient magnitude to stabilize low satellite orbits against orbital decay from atmospheric drag, and (3) to test the magsail concept. These all appear to be capable of being tested using the same deployed high temperature superconducting coil. In certain orbits, high temperature superconducting wire, which has now been developed to the point where silver-sheathed high T sub c wires one mm in diameter are commercially available, can be used to produce the magnetic moments required for shielding without requiring any mechanical cooling system. The potential benefits of this concept apply directly to both earth-orbital and interplanetary missions. The usefulness of a protective shield for manned missions needs scarcely to be emphasized. Similarly, the usefulness of increasing orbit perigee without expenditure of propellant is obvious. This payload would be a first step in assessing the true potential of large volume magnetic fields in the US space program. The objective of this design research is to develop an innovative, prototype deployed high temperature superconducting coil (DHTSC) system.

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

Lackner, Friedrich; Ferracin, Paolo; Todesco, Ezio

The High luminosity LHC upgrade target is to increase the integrated luminosity by a factor 10, resulting in an integrated luminosity of 3000 fb-1. One major improvement foreseen is the reduction of the beam size at the collision points. This requires the development of 150 mm single aperture quadrupoles for the interaction regions. These quadrupoles are under development in a joint collaboration between CERN and the US-LHC Accelerator Research Program (LARP). The chosen approach for achieving a nominal quadrupole field gradient of 132.6 T/m is based on the Nb3Sn technology. The coils with a length of 7281 mm will bemore » the longest Nb3Sn coils fabricated so far for accelerator magnets. The production of the long coils was launched in 2016 based on practise coils made from copper. This paper provides a status of the production of the first low grade and full performance coils and describes the production process and applied quality control. Furthermore an outlook for the prototype assembly is provided.« less

Dimensional changes of Nb 3Sn Rutherford cables during heat treatment

DOE PAGES

Rochepault, E.; Ferracin, P.; Ambrosio, G.; ...

2016-06-01

In high field magnet applications, Nb 3Sn coils undergo a heat treatment step after winding. During this stage, coils radially expand and longitudinally contract due to the Nb 3Sn phase change. In order to prevent residual strain from altering superconducting performances, the tooling must provide the adequate space for these dimensional changes. The aim of this paper is to understand the behavior of cable dimensions during heat treatment and to provide estimates of the space to be accommodated in the tooling for coil expansion and contraction. In addition, this paper summarizes measurements of dimensional changes on strands, single Rutherford cables,more » cable stacks, and coils performed between 2013 and 2015. These samples and coils have been performed within a collaboration between CERN and the U.S. LHC Accelerator Research Program to develop Nb 3Sn quadrupole magnets for the HiLumi LHC. The results are also compared with other high field magnet projects.« less

Field Quality Study of a 1-m-Long Single-Aperture 11-T Nb$$_3$$Sn Dipole Model for LHC Upgrades

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

Chlachidze, G.; DiMarco, J.; Andreev, N.

2014-01-01

FNAL and CERN are carrying out a joint R&D program with the goal of building a 5.5-m-long twin-aperture 11-T Nb_3Sn dipole prototype that is suitable for installation in the LHC. An important part of the program is the development and test of a series of short single-aperture and twin-aperture dipole models with a nominal field of 11 T at the LHC operation current of 11.85 kA and 20% margin. This paper presents the results of magnetic measurements of a 1-m-long single-aperture Nb_3Sn dipole model fabricated and tested recently at FNAL, including geometrical field harmonics and effects of coil magnetization andmore » iron yoke saturation.« less

Fabrication of a helical coil shape memory alloy actuator

NASA Astrophysics Data System (ADS)

Odonnell, R. E.

1992-02-01

A fabrication process was developed to form, heat treat, and join NiTi shape memory alloy helical coils for use as mechanical actuators. Tooling and procedures were developed to wind both extension and compression-type coils on a manual lathe. Heat treating fixtures and techniques were used to set the 'memory' of the NiTi alloy to the desired configuration. A swaging process was devised to fasten shape memory alloy extension coils to end fittings for use in actuator testing and for potential attachment to mechanical devices. The strength of this mechanical joint was evaluated.

Prediction, experimental results and analysis of the ITER TF insert coil quench propagation tests, using the 4C code

NASA Astrophysics Data System (ADS)

Zanino, R.; Bonifetto, R.; Brighenti, A.; Isono, T.; Ozeki, H.; Savoldi, L.

2018-07-01

The ITER toroidal field insert (TFI) coil is a single-layer Nb3Sn solenoid tested in 2016-2017 at the National Institutes for Quantum and Radiological Science and Technology (former JAEA) in Naka, Japan. The TFI, the last in a series of ITER insert coils, was tested in operating conditions relevant for the actual ITER TF coils, inserting it in the borehole of the central solenoid model coil, which provided the background magnetic field. In this paper, we consider the five quench propagation tests that were performed using one or two inductive heaters (IHs) as drivers; out of these, three used just one IH but with increasing delay times, up to 7.5 s, between the quench detection and the TFI current dump. The results of the 4C code prediction of the quench propagation up to the current dump are presented first, based on simulations performed before the tests. We then describe the experimental results, showing good reproducibility. Finally, we compare the 4C code predictions with the measurements, confirming the 4C code capability to accurately predict the quench propagation, and the evolution of total and local voltages, as well as of the hot spot temperature. To the best of our knowledge, such a predictive validation exercise is performed here for the first time for the quench of a Nb3Sn coil. Discrepancies between prediction and measurement are found in the evolution of the jacket temperatures, in the He pressurization and quench acceleration in the late phase of the transient before the dump, as well as in the early evolution of the inlet and outlet He mass flow rate. Based on the lessons learned in the predictive exercise, the model is then refined to try and improve a posteriori (i.e. in interpretive, as opposed to predictive mode) the agreement between simulation and experiment.

Numerical simulation for the magnetic force distribution in electromagnetic forming of small size flat sheet

NASA Astrophysics Data System (ADS)

Chen, Xiaowei; Wang, Wenping; Wan, Min

2013-12-01

It is essential to calculate magnetic force in the process of studying electromagnetic flat sheet forming. Calculating magnetic force is the basis of analyzing the sheet deformation and optimizing technical parameters. Magnetic force distribution on the sheet can be obtained by numerical simulation of electromagnetic field. In contrast to other computing methods, the method of numerical simulation has some significant advantages, such as higher calculation accuracy, easier using and other advantages. In this paper, in order to study of magnetic force distribution on the small size flat sheet in electromagnetic forming when flat round spiral coil, flat rectangular spiral coil and uniform pressure coil are adopted, the 3D finite element models are established by software ANSYS/EMAG. The magnetic force distribution on the sheet are analyzed when the plane geometries of sheet are equal or less than the coil geometries under fixed discharge impulse. The results showed that when the physical dimensions of sheet are less than the corresponding dimensions of the coil, the variation of induced current channel width on the sheet will cause induced current crowding effect that seriously influence the magnetic force distribution, and the degree of inhomogeneity of magnetic force distribution is increase nearly linearly with the variation of induced current channel width; the small size uniform pressure coil will produce approximately uniform magnetic force distribution on the sheet, but the coil is easy to early failure; the desirable magnetic force distribution can be achieved when the unilateral placed flat rectangular spiral coil is adopted, and this program can be take as preferred one, because the longevity of flat rectangular spiral coil is longer than the working life of small size uniform pressure coil.

Experience with helium leak and thermal shocks test of SST-1 cryo components

NASA Astrophysics Data System (ADS)

Sharma, Rajiv; Nimavat, Hiren; Srikanth, G. L. N.; Bairagi, Nitin; Shah, Pankil; Tanna, V. L.; Pradhan, S.

2012-11-01

A steady state superconducting Tokamak SST-1 is presently under its assembly stage at the Institute for Plasma Research. The SST-1 machine is a family of Superconducting SC coils for both Toroidal field and Poloidal Field. An ultra high vacuum compatible vacuum vessel, placed in the bore of the TF coils, houses the plasma facing components. A high vacuum cryostat encloses all the SC coils and the vacuum vessel. Liquid Nitrogen (LN2) cooled thermal shield between the vacuum vessel & SC coils as well as between cryostat and the SC coils. There are number of crucial cryogenic components as Electrical isolators, 80 K thermal shield, Cryogenic flexible hose etc., which have to be passed the performance validation tests as part of fulfillment of the stringent QA/QC before incorporated in the main assembly. The individual leak tests of components at RT as well as after thermal cycle from 300 K to 77 K ensure us to make final overall leak proof system. These components include, Large numbers of Electrical Isolators for Helium as well as LN2 services, Flexible Bellows and Hoses for Helium as well as LN2 services, Thermal shock tests of large numbers of 80 K Bubble shields In order to validate the helium leak tightness of these components, we have used the calibrated mass spectrometer leak detector (MSLD) at 300 K, 77 K and 4.2. Since it is very difficult to locate the leaks, which are appearing at rather lower temperatures e.g. less than 20 K, We have invented different approaches to resolve the issue of such leaks. This paper, in general describes the design of cryogenic flexible hose, assembly, couplings for leak testing, test method and techniques of thermal cycles test at 77 K inflow conditions and leak testing aspects of different cryogenic components. The test results, the problems encountered and its solutions techniques are discussed.

Mechanisms of Healing in Coiled Intracranial Aneurysms: A Review of the Literature

PubMed Central

Brinjikji, Waleed; Kallmes, David F; Kadirvel, Ramanathan

2016-01-01

Summary Recanalization of intracranial aneurysms following endovascular coiling remains a frustratingly common occurrence. An understanding of the molecular and histopathological mechanisms of aneurysm healing following coil embolization is essential to improving aneurysm occlusion rates. Histolopathologic studies in coiled human and experimental aneurysms suggest that during the first month post-coiling, thrombus formation and active inflammation occur within the aneurysm dome. Several months following embolization, the aneurysm is excluded from the parent vessel by formation of a neointimal layer, which is often thin and discontinuous, across the aneurysm neck. Numerous coil modifications and systemic therapies have been tested in animals and humans in an attempt to improve the aneurysm healing process; these modifications have met with variable levels of success. In this review, we summarize the histopathologic and molecular biology of aneurysm healing and discuss how these findings have been applied in an attempt to improve angiographic outcomes in patients harboring intracranial aneurysm. PMID:25430855

Cryocooler based test setup for high current applications

NASA Astrophysics Data System (ADS)

Pradhan, Jedidiah; Das, Nisith Kr.; Roy, Anindya; Duttagupta, Anjan

2018-04-01

A cryo-cooler based cryogenic test setup has been designed, fabricated, and tested. The setup incorporates two numbers of cryo-coolers, one for sample cooling and the other one for cooling the large magnet coil. The performance and versatility of the setup has been tested using large samples of high-temperature superconductor magnet coil as well as short samples with high current. Several un-calibrated temperature sensors have been calibrated using this system. This paper presents the details of the system along with results of different performance tests.

A polyvalent harmonic coil testing method for small-aperture magnets

NASA Astrophysics Data System (ADS)

Arpaia, Pasquale; Buzio, Marco; Golluccio, Giancarlo; Walckiers, Louis

2012-08-01

A method to characterize permanent and fast-pulsed iron-dominated magnets with small apertures is presented. The harmonic coil measurement technique is enhanced specifically for small-aperture magnets by (1) in situ calibration, for facing search-coil production inaccuracy, (2) rotating the magnet around its axis, for correcting systematic effects, and (3) measuring magnetic fluxes by stationary coils at different angular positions for measuring fast pulsed magnets. This method allows a quadrupole magnet for particle accelerators to be characterized completely, by assessing multipole field components, magnetic axis position, and field direction. In this paper, initially the metrological problems arising from testing small-aperture magnets are highlighted. Then, the basic ideas of the proposed method and the architecture of the corresponding measurement system are illustrated. Finally, experimental validation results are shown for small-aperture permanent and fast-ramped quadrupole magnets for the new linear accelerator Linac4 at CERN (European Organization for Nuclear Research).

NON-DESTRUCTIVE FLAW DETECTION APPARATUS

DOEpatents

Stateman, M.J.; Holloway, H.R.

1957-12-17

An apparatus is described for the non-destructive detection of flaws in electrical conducting articles. The particular feature of the detection apparatus is that a flaw in the front or back of the test article will not be masked by signals caused by the passage of the end and front of the article through the detection apparatus. The present invention alleviates the above problem by mounting detection coils on directly opposite sides of the test passageway so that the axes of the pickup coils are perpendicular to the axis of an energizing coil through which the article is passed. A flaw in the article will cause a change in the voltage induced in one pickup coil, but passage of the end or front of the article will not produce unequal signals. The signals are compared in appropriate electrical circuitry to actuate a recorder only when unequal signals are present, indicating the presence of a flaw.

A Specialized Multi-Transmit Head Coil for High Resolution fMRI of the Human Visual Cortex at 7T.

PubMed

Sengupta, Shubharthi; Roebroeck, Alard; Kemper, Valentin G; Poser, Benedikt A; Zimmermann, Jan; Goebel, Rainer; Adriany, Gregor

2016-01-01

To design, construct and validate radiofrequency (RF) transmit and receive phased array coils for high-resolution visual cortex imaging at 7 Tesla. A 4 channel transmit and 16 channel receive array was constructed on a conformal polycarbonate former. Transmit field efficiency and homogeneity were simulated and validated, along with the Specific Absorption Rate, using [Formula: see text] mapping techniques and electromagnetic simulations. Receiver signal-to-noise ratio (SNR), temporal SNR (tSNR) across EPI time series, g-factors for accelerated imaging and noise correlations were evaluated and compared with a commercial 32 channel whole head coil. The performance of the coil was further evaluated with human subjects through functional MRI (fMRI) studies at standard and submillimeter resolutions of upto 0.8mm isotropic. The transmit and receive sections were characterized using bench tests and showed good interelement decoupling, preamplifier decoupling and sample loading. SNR for the 16 channel coil was ∼ 1.5 times that of the commercial coil in the human occipital lobe, and showed better g-factor values for accelerated imaging. fMRI tests conducted showed better response to Blood Oxygen Level Dependent (BOLD) activation, at resolutions of 1.2mm and 0.8mm isotropic. The 4 channel phased array transmit coil provides homogeneous excitation across the visual cortex, which, in combination with the dual row 16 channel receive array, makes for a valuable research tool for high resolution anatomical and functional imaging of the visual cortex at 7T.

SU-F-J-143: Initial Assessment of Image Quality of An Integrated MR-Linac System with ACR Phantom

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

Wang, J; Fuller, C; Yung, J

Purpose/Objective(s): To assess the image quality of an integrated MR-Linac system and compare with other MRI systems that are primarily used for diagnostic purposes. Materials/Methods: An ACR MRI quality control (QC) phantom was used to evaluate the image quality of a fully integrated 1.5T MRI-Linac system recently installed at our institution. This system has a new split magnet design which gives the magnetic field strength of 1.5T. All images were acquired with a set of phased-array surface coils which are designed to have minimal attention of radiation beam. The anterior coil rests on a coil holder which keeps the anteriormore » coil’s position consistent for QA purposes. The posterior coil is imbedded in the patient couch. Multiple sets of T1, T2/PD images were acquired using the protocols as prescribed by the ACR on three different dates, ranging 3 months apart. Results: The geometric distortion are within 0.5 mm in the axial scans and within 1mm in the saggital (z-direction) scans. Slice thickness accuracy, image uniformity, ghosting ratio, high contrast detectability are comparable to other 1.5T diagnostic MRI scanners. The low-contrast object detectability are lower comparatively, which is a result of using the body array coil. Additionally, the beam’s-eye-view images (oblique coronal and saggital images) have minimal geometric distortion at all linac gantry angles tested. No observable changes or drift in image quality is found from images acquired 3 month apart. Conclusion: Despite the use of a body array surface coil, the image quality is comparable to that of an 1.5T MRI scanner and is of sufficient quality to pass the ACR MRI accreditation program. The geometric distortion of the MRI system of the integrated MR-Linac is within 1mm for an object size similar to the ACR phantom, sufficient for radiation therapy treatment purpose. The authors received corporate sponsored research grants from Elekta which is the vendor for the MR-Linac evaluated in this study.« less

Attenuation correction for flexible magnetic resonance coils in combined magnetic resonance/positron emission tomography imaging.

PubMed

Eldib, Mootaz; Bini, Jason; Calcagno, Claudia; Robson, Philip M; Mani, Venkatesh; Fayad, Zahi A

2014-02-01

Attenuation correction for magnetic resonance (MR) coils is a new challenge that came about with the development of combined MR and positron emission tomography (PET) imaging. This task is difficult because such coils are not directly visible on either PET or MR acquisitions with current combined scanners and are therefore not easily localized in the field of view. This issue becomes more evident when trying to localize flexible MR coils (eg, cardiac or body matrix coil) that change position and shape from patient to patient and from one imaging session to another. In this study, we proposed a novel method to localize and correct for the attenuation and scatter of a flexible MR cardiac coil, using MR fiducial markers placed on the surface of the coil to allow for accurate registration of a template computed tomography (CT)-based attenuation map. To quantify the attenuation properties of the cardiac coil, a uniform cylindrical water phantom injected with 18F-fluorodeoxyglucose (18F-FDG) was imaged on a sequential MR/PET system with and without the flexible cardiac coil. After establishing the need to correct for the attenuation of the coil, we tested the feasibility of several methods to register a precomputed attenuation map to correct for the attenuation. To accomplish this, MR and CT visible markers were placed on the surface of the cardiac flexible coil. Using only the markers as a driver for registration, the CT image was registered to the reference image through a combination of rigid and deformable registration. The accuracy of several methods was compared for the deformable registration, including B-spline, thin-plate spline, elastic body spline, and volume spline. Finally, we validated our novel approach both in phantom and patient studies. The findings from the phantom experiments indicated that the presence of the coil resulted in a 10% reduction in measured 18F-FDG activity when compared with the phantom-only scan. Local underestimation reached 22% in regions of interest close to the coil. Various registration methods were tested, and the volume spline was deemed to be the most accurate, as measured by the Dice similarity metric. The results of our phantom experiments showed that the bias in the 18F-FDG quantification introduced by the presence of the coil could be reduced by using our registration method. An overestimation of only 1.9% of the overall activity for the phantom scan with the coil attenuation map was measured when compared with the baseline phantom scan without coil. A local overestimation of less than 3% was observed in the ROI analysis when using the proposed method to correct for the attenuation of the flexible cardiac coil. Quantitative results from the patient study agreed well with the phantom findings. We presented and validated an accurate method to localize and register a CT-based attenuation map to correct for the attenuation and scatter of flexible MR coils. This method may be translated to clinical use to produce quantitatively accurate measurements with the use of flexible MR coils during MR/PET imaging.

A Hermetic Wireless Subretinal Neurostimulator for Vision Prostheses

PubMed Central

Shire, Douglas B.; Chen, Jinghua; Doyle, Patrick; Gingerich, Marcus D.; Cogan, Stuart F.; Drohan, William A.; Behan, Sonny; Theogarajan, Luke; Wyatt, John L.; Rizzo, Joseph F.

2016-01-01

A miniaturized, hermetically encased, wirelessly operated retinal prosthesis has been developed for preclinical studies in the Yucatan minipig, and includes several design improvements over our previously reported device. The prosthesis attaches conformally to the outside of the eye and electrically drives a microfabricated thin-film polyimide array of sputtered iridium oxide film electrodes. This array is implanted into the subretinal space using a customized ab externo surgical technique. The implanted device includes a hermetic titanium case containing a 15-channel stimulator chip and discrete circuit components. Feedthroughs in the case connect the stimulator chip to secondary power and data receiving coils on the eye and to the electrode array under the retina. Long-term in vitro pulse testing of the electrodes projected a lifetime consistent with typical devices in industry. The final assembly was tested in vitro to verify wireless operation of the system in physiological saline using a custom RF transmitter and primary coils. Stimulation pulse strength, duration, and frequency were programmed wirelessly from a Peripheral Component Interconnect eXtensions for Instrumentation (PXI) computer. Operation of the retinal implant has been verified in two pigs for up to five and a half months by detecting stimulus artifacts generated by the implanted device. PMID:21859595

A household randomized, controlled trial of the efficacy of 0.03% transfluthrin coils alone and in combination with long-lasting insecticidal nets on the incidence of Plasmodium falciparum and Plasmodium vivax malaria in Western Yunnan Province, China.

PubMed

Hill, Nigel; Zhou, Hong Ning; Wang, Piyu; Guo, Xiaofang; Carneiro, Ilona; Moore, Sarah J

2014-05-31

Mosquito coils are the most commonly used household insecticidal product in the world with sales exceeding 50 billion coils, used by two billion people worldwide annually. Despite strong evidence that coils prevent mosquito bites a systematic review concluded that there is no evidence that burning mosquito coils prevents malaria acquisition. Therefore, the current trial was designed to measure and compare prevention of malaria infection by mosquito coils or long-lasting insecticidal net (LLIN) or a combination of the two in Yunnan, China in the Greater Mekong sub-region. A four-arm single blind household-randomized design was chosen as coils emanate insecticide throughout the household. Households enrolled at baseline were randomly allocated by the lottery method to one of the four intervention arms: (i) nothing, (ii) 0.03% transfluthrin coils alone, (iii) deltamethrin long-lasting insecticide treated nets, (LLINs) alone or (iv) a combination of transfluthrin coils and deltamethrin LLINs. All household members were recruited to the study, with only those households excluded with pregnant or breastfeeding mothers, members with chest complaints or allergies or members that regularly slept away from home. The main outcome of interest was Plasmodium falciparum malaria prevalence detected by rapid diagnostic tests (RDTs) during six repeated monthly cross-sectional surveys. The secondary outcome of interest was the effect on Plasmodium vivax prevalence detected in the same way. A total of 2,052 households were recruited into the study, comprising 7,341 individuals The odds ratios of testing positive by RDT with P. falciparum or P. vivax were >75% lower for all intervention arms compared with the control arm. Coils alone provided 77% protection (95% CI: 50%-89%), LLINs provided 91% protection (95% CI: 72%-97%) and the combination of coils and LLINs provided 94% protection (95% CI: 77%-99%) against P. falciparum compared with the control arm. There was no statistically significant difference between the protective efficacies of the different interventions. This is the first robust clinical evaluation of transfluthrin mosquito coils as a means to reduce malaria and the high degree of infection prevented would indicate they represent a potentially highly effective tool, which could be integrated into larger vector control programmes. ClinicalTrials.gov Identifier: NCT00442442, March 2007.

Enhanced heat transfer and frictional losses in heat exchanger tube with modified helical coiled inserts

NASA Astrophysics Data System (ADS)

Verma, Aditya; Kumar, Manoj; Patil, Anil Kumar

2018-04-01

The application of compact heat exchangers in any thermal system improves overall performance with a considerable reduction in size and weight. Inserts of different geometrical features have been used as turbulence promoting devices to increase the heat transfer rates. The present study deals with the experimental investigation of heat transfer and fluid flow characteristics of a tubular heat exchanger fitted with modified helical coiled inserts. Experiments have been carried out for a smooth tube without insert, tube fitted with helical coiled inserts, and modified helical coiled inserts. The helical coiled inserts are tested by varying the pitch ratio and wire diameter ratio from 0.5-1.5, and 0.063-0.125, respectively for the Reynolds number range of 1400 to 11,000. Experimental data have also been collected for the modified helical coiled inserts with gradually increasing pitch (GIP) and gradually decreasing pitch (GDP) configurations. The Nusselt number and friction factor values for helical coiled inserts are enhanced in the range of 1.42-2.62, 3.4-27.4, relative to smooth tube, respectively. The modified helical coiled insert showed enhancements in Nusselt number and friction factor values in the range of 1.49-3.14, 11.2-19.9, relative to smooth tube, respectively. The helical coiled and modified helical coiled inserts have thermo-hydraulic performance factor in the range of 0.59-1.29, 0.6-1.39, respectively. The empirical correlations of Nusselt number and friction factor for helical coiled inserts are proposed.

Magnetic Catheter Manipulation in the Interventional MRI Environment

PubMed Central

Wilson, Mark W.; Martin, Alastair B.; Lillaney, Prasheel; Losey, Aaron D.; Yee, Erin J.; Bernhardt, Anthony; Malba, Vincent; Evans, Lee; Sincic, Ryan; Saeed, Maythem; Arenson, Ronald L.; Hetts, Steven W.

2013-01-01

Purpose To evaluate deflection capability of a prototype endovascular catheter, which is remotely magnetically steerable, for use in the interventional MRI environment. Materials and Methods Copper coils were mounted on the tips of commercially available 2.3 – 3.0 Fr microcatheters. The coils were fabricated in a novel manner by plasma vapor deposition of a copper layer followed by laser lithography of the layer into coils. Orthogonal helical (solenoid) and saddle-shaped (Helmholtz) coils were mounted on a single catheter tip. Microcatheters were tested in water bath phantoms in a 1.5T clinical MRI scanner, with variable simultaneous currents applied to the coils. Catheter tip deflection was imaged in the axial plane utilizing a “real-time” steady-state free precession (SSFP) MRI sequence. Degree of deflection and catheter tip orientation were measured for each current application. Results The catheter tip was clearly visible in the longitudinal and axial planes. Magnetic field artifacts were visible when the orthogonal coils at the catheter tip were energized. Variable amounts of current applied to a single coil demonstrated consistent catheter deflection in all water bath experiments. Changing current polarity reversed the observed direction of deflection, whereas current applied to two different coils resulted in deflection represented by the composite vector of individual coil activations. Microcatheter navigation through the vascular phantom was successful through control of applied current to one or more coils. Conclusion Controlled catheter deflection is possible with laser lithographed multi-axis coil tipped catheters in the MRI environment. PMID:23707097

Design and prototype fabrication of a 30 tesla cryogenic magnet

NASA Technical Reports Server (NTRS)

Prok, G. M.; Swanson, M. C.; Brown, G. V.

1977-01-01

A liquid neon cooled magnet was designed to produce 30 teslas in steady operation. To ensure the correctness of the heat transfer relationships used, supercritical neon heat transfer tests were made. Other tests made before the final design included tests on the effect of the magnetic field on pump motors, tensile shear tests on the cryogenic adhesives, and simulated flow studies for the coolant. The magnet will consist of two pairs of coils, cooled by forced convection of supercritical neon. Heat from the supercritical neon will be rejected through heat exchangers which are made of roll bonded copper panels and are submerged in a pool of saturated liquid neon. A partial mock up coil was wound to identify the tooling required to wind the magnet. This was followed by winding a prototype pair of coils. The prototype winding established procedures for fabricating the final magnet and revealed slight changes needed in the final design.

High-field superconducting nested coil magnet

NASA Technical Reports Server (NTRS)

Laverick, C.; Lobell, G. M.

1970-01-01

Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

A wide linear range Eddy Current Displacement Sensor equipped with dual-coil probe applied in the Magnetic Suspension Flywheel.

PubMed

Fang, Jiancheng; Wen, Tong

2012-01-01

The Eddy Current Displacement Sensor (ECDS) is widely used in the Magnetic Suspension Flywheel (MSFW) to measure the tiny clearance between the rotor and the magnetic bearings. The linear range of the ECDS is determined by the diameter of its probe coil. Wide clearances must be measured in some new MSFWs recently designed for the different space missions, but the coil diameter is limited by some restrictions. In this paper, a multi-channel ECDS equipped with dual-coil probes is proposed to extend the linear range to satisfy the demands of such MSFWs. In order to determine the best configuration of the dual-coil probe, the quality factors of the potential types of the dual-coil probes, the induced eddy current and the magnetic intensity on the surface of the measuring object are compared with those of the conventional single-coil probe. The linear range of the ECDS equipped with the selected dual-coil probe is extended from 1.1 mm to 2.4 mm under the restrictions without adding any cost for additional compensation circuits or expensive coil materials. The effectiveness of the linear range extension ability and the dynamic response of the designed ECDS are confirmed by the testing and the applications in the MSFW.

Cooling a solar telescope enclosure: plate coil thermal analysis

NASA Astrophysics Data System (ADS)

Gorman, Michael; Galapon, Chriselle; Montijo, Guillermo; Phelps, LeEllen; Murga, Gaizka

2016-08-01

The climate of Haleakalā requires the observatories to actively adapt to changing conditions in order to produce the best possible images. Observatories need to be maintained at a temperature closely matching ambient or the images become blurred and unusable. The Daniel K. Inouye Solar Telescope is a unique telescope as it will be active during the day as opposed to the other night-time stellar observatories. This means that it will not only need to constantly match the ever-changing temperature during the day, but also during the night so as not to sub-cool and affect the view field of other telescopes while they are in use. To accomplish this task, plate coil heat exchanger panels will be installed on the DKIST enclosure that are designed to keep the temperature at ambient temperature +0°C/-4°C. To verify the feasibility of this and to validate the design models, a test rig has been installed at the summit of Haleakalā. The project's purpose is to confirm that the plate coil panels are capable of maintaining this temperature throughout all seasons and involved collecting data sets of various variables including pressures, temperatures, coolant flows, solar radiations and wind velocities during typical operating hours. Using MATLAB, a script was written to observe the plate coil's thermal performance. The plate coil did not perform as expected, achieving a surface temperature that was generally 2ºC above ambient temperature. This isn't to say that the plate coil does not work, but the small chiller used for the experiment was undersized resulting in coolant pumped through the plate coil that was not supplied at a low enough temperature. Calculated heat depositions were about 23% lower than that used as the basis of the design for the hillers to be used on the full system, a reasonable agreement given the fact that many simplifying assumptions were used in the models. These were not carried over into the testing. The test rig performance showing a 23% margin provides a high degree of confidence for the performance of the full system when it is installed. If time allows, additional testing could be done that includes additional incident angles and times of day. This would allow a more complete analysis. If additional testing were to be performed, it's recommended to use a larger chiller capable of reaching lower temperatures. The test rig design could also be optimized in order to bring the plate coil up to its maximum efficiency. In the future, the script could be rewritten in a different computer language, so that the data could be solved for quicker. Further analysis could also include different types of coolants.

The DARWIN breadboard cryogenic optical delay line

NASA Astrophysics Data System (ADS)

van den Dool, T. C.; Gielesen, W.; Kamphues, F.; Loix, N.; Kooijman, P. P.; de Vries, C.; van Weers, H.; Fleury, K.; Stockman, Y.; Velsink, G.; Benoit, J.; Poupinet, A.; Sève, F.

2017-11-01

TNO, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line (figure 1) for use in future space interferometry missions. The work is performed under ESA contract 17.747/03 in preparation for the DARWIN mission. The breadboard (BB) delay line is representative of a flight mechanism. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a twomirror cat's eye. Magnetic bearings provide frictionless and wear free operation with zero-hysteresis. The design of the BB delay line has been completed. The development test program, including operation at 100 K has been completed. The verification test programme is currently being carried out and will include functional testing at 40 K.

Ferromagnetic resonance probe liftoff suppression apparatus

DOEpatents

Davis, Thomas J.; Tomeraasen, Paul L.

1985-01-01

A liftoff suppression apparatus utilizing a liftoff sensing coil to sense the amount a ferromagnetic resonance probe lifts off the test surface during flaw detection and utilizing the liftoff signal to modulate the probe's field modulating coil to suppress the liftoff effects.

A polymer driveshaft for use in orbital and rotational atherectomy

NASA Astrophysics Data System (ADS)

Grothe, Preston Lee

Driveshafts used in atherectomy medical devices are often comprised of coiled or braided metal wires. These constructions are designed to tolerate delivery through tortuous vessels and can endure high speed rotation used during activation of the atherectomy treatment. This research investigated polymer driveshaft designs, which were comprised of polymer inner and outer layers, and coiled or braided stainless steel wires. The polymer driveshaft materials included polyimide, nylon 12, and polytetrafluoroethylene (PTFE). Mechanical testing of polymer driveshafts was conducted to determine material response in bending, tension, compression, and torsion. The polymer driveshaft test results were then compared with current coiled metal wire driveshaft constructions. The investigation identified polymer driveshaft options that could feasibly work in an atherectomy application.

Design, Construction and Test of Cryogen-Free HTS Coil Structure

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

Hocker, H.; Anerella, M.; Gupta, R.

2011-03-28

This paper will describe design, construction and test results of a cryo-mechanical structure to study coils made with the second generation High Temperature Superconductor (HTS) for the Facility for Rare Isotope Beams (FRIB). A magnet comprised of HTS coils mounted in a vacuum vessel and conduction-cooled with Gifford-McMahon cycle cryocoolers is used to develop and refine design and construction techniques. The study of these techniques and their effect on operations provides a better understanding of the use of cryogen free magnets in future accelerator projects. A cryogen-free, superconducting HTS magnet possesses certain operational advantages over cryogenically cooled, low temperature superconductingmore » magnets.« less

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

Ozeki, H.; Isono, T.; Uno, Y.

JAEA successfully completed the manufacture of the toroidal field (TF) insert coil (TFIC) for a performance test of the ITER TF conductor in the final design in cooperation with Hitachi, Ltd. The TFIC is a single-layer 8.875-turn solenoid coil with 1.44-m diameter. This will be tested for 68-kA current application in a 13-T external magnetic field. TFIC was manufactured in the following order: winding of the TF conductor, lead bending, fabrication of the electrical termination, heat treatment, turn insulation, installation of the coil into the support mandrel structure, vacuum pressure impregnation (VPI), structure assembly, and instrumentation. Here in this presentation,more » manufacture process and quality control status for the TFIC manufacturing are reported.« less

Construction and component testing of TAMU3, a 14 Tesla stress-managed Nb3Sn model dipole

NASA Astrophysics Data System (ADS)

Holik, Eddie Frank, III; Benson, Chris; Blackburn, Raymond; Diaczenko, Nick; Elliott, Timothy; Jaisle, Andrew; McInturff, A.; McIntyre, P.; Sattarov, Akhdiyor

2012-06-01

We report the construction and testing of components of TAMU3, a 14 Tesla Nb3Sn block-coil dipole. A primary goal in developing this model dipole is to test a method of stress management in which Lorentz stress is intercepted within the coil assembly and bypassed so that it cannot accumulate to a level that would cause strain degradation in the superconducting windings. Details of the fabrication, tooling, and results of construction and magnet component testing will be presented.

Performance of a 12-coil superconducting bumpy torus magnet facility

NASA Technical Reports Server (NTRS)

Roth, J. R.; Holmes, A. D.; Keller, T. A.; Krawczonek, W. M.

1972-01-01

The bumpy torus facility consists of 12 superconducting coils, each 19 cm i.d. and capable of 3.0 teslas on their axes. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m, and are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Final shakedown tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The facility is now ready for use as a plasma physics research facility. A maximum magnetic field on the magnetic axis of 3.23 teslas was held for a period of more than sixty minutes without a coil normalcy. The design field was 3.00 teslas. The steady-state liquid helium boil-off rate was 87 liters per hour of liquid helium without the coils charged. The coil array was stable when subjected to an impulsive loading, even with the magnets fully charged. When the coils were charged to a maximum magnetic field of 3.35 teslas, the system was driven normal without damage.

Demonstration of a stand-alone cylindrical fiber coil for optical amplifiers

NASA Astrophysics Data System (ADS)

Laxton, Steven R.; Bravo, Tyler; Madsen, Christi K.

2015-08-01

The design, fabrication and measurement of a cylindrical fiber coil structure is presented that has applications for compact fiber-optic amplifiers. A multimode fiber is used as a surrogate for a dual clad, rare-earth doped fiber for coil fabrication and optical testing. A ray trace algorithm, written in Python, was used to simulate the behavior of light travelling along the waveguide path. An in-house fabrication method was developed using 3D printed parts designed in SolidWorks and assembled with Arduino-controlled stepper motors for coil winding. Ultraviolet-cured epoxy was used to bind the coils into a rigid cylinder. Bend losses are introduced by the coil, and a measurement of the losses for two coil lengths was obtained experimentally. The measurements confirm that bend losses through a multimode fiber, representative of pump light propagating in a dual-clad rare-earth doped fiber, are relatively wavelength independent over a large spectral range and that higher order modes are extinguished quickly while lower order modes transmit through the windings with relatively low loss.

Recent advances in stellarator optimization

DOE PAGES

Gates, D. A.; Boozer, A. H.; Brown, T.; ...

2017-10-27

Computational optimization has revolutionized the field of stellarator design. To date, optimizations have focused primarily on optimization of neoclassical confinement and ideal MHD stability, although limited optimization of other parameters has also been performed. Here, we outline a select set of new concepts for stellarator optimization that, when taken as a group, present a significant step forward in the stellarator concept. One of the criticisms that has been leveled at existing methods of design is the complexity of the resultant field coils. Recently, a new coil optimization code—COILOPT++, which uses a spline instead of a Fourier representation of the coils,—wasmore » written and included in the STELLOPT suite of codes. The advantage of this method is that it allows the addition of real space constraints on the locations of the coils. The code has been tested by generating coil designs for optimized quasi-axisymmetric stellarator plasma configurations of different aspect ratios. As an initial exercise, a constraint that the windings be vertical was placed on large major radius half of the non-planar coils. Further constraints were also imposed that guaranteed that sector blanket modules could be removed from between the coils, enabling a sector maintenance scheme. Results of this exercise will be presented. New ideas on methods for the optimization of turbulent transport have garnered much attention since these methods have led to design concepts that are calculated to have reduced turbulent heat loss. We have explored possibilities for generating an experimental database to test whether the reduction in transport that is predicted is consistent with experimental observations. Thus, a series of equilibria that can be made in the now latent QUASAR experiment have been identified that will test the predicted transport scalings. Fast particle confinement studies aimed at developing a generalized optimization algorithm are also discussed. A new algorithm developed for the design of the scraper element on W7-X is presented along with ideas for automating the optimization approach.« less

Recent advances in stellarator optimization

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

Gates, D. A.; Boozer, A. H.; Brown, T.

Computational optimization has revolutionized the field of stellarator design. To date, optimizations have focused primarily on optimization of neoclassical confinement and ideal MHD stability, although limited optimization of other parameters has also been performed. Here, we outline a select set of new concepts for stellarator optimization that, when taken as a group, present a significant step forward in the stellarator concept. One of the criticisms that has been leveled at existing methods of design is the complexity of the resultant field coils. Recently, a new coil optimization code—COILOPT++, which uses a spline instead of a Fourier representation of the coils,—wasmore » written and included in the STELLOPT suite of codes. The advantage of this method is that it allows the addition of real space constraints on the locations of the coils. The code has been tested by generating coil designs for optimized quasi-axisymmetric stellarator plasma configurations of different aspect ratios. As an initial exercise, a constraint that the windings be vertical was placed on large major radius half of the non-planar coils. Further constraints were also imposed that guaranteed that sector blanket modules could be removed from between the coils, enabling a sector maintenance scheme. Results of this exercise will be presented. New ideas on methods for the optimization of turbulent transport have garnered much attention since these methods have led to design concepts that are calculated to have reduced turbulent heat loss. We have explored possibilities for generating an experimental database to test whether the reduction in transport that is predicted is consistent with experimental observations. Thus, a series of equilibria that can be made in the now latent QUASAR experiment have been identified that will test the predicted transport scalings. Fast particle confinement studies aimed at developing a generalized optimization algorithm are also discussed. A new algorithm developed for the design of the scraper element on W7-X is presented along with ideas for automating the optimization approach.« less

Impact of endobronchial coiling on segmental bronchial lumen in treated and untreated lung lobes: Correlation with changes in lung volume, clinical and pulmonary function tests.

PubMed

Kloth, C; Thaiss, W M; Hetzel, J; Ditt, H; Grosse, U; Nikolaou, K; Horger, M

2016-07-01

To assess the impact of endobronchial coiling on the segment bronchus cross-sectional area and volumes in patients with lung emphysema using quantitative chest-CT measurements. Thirty patients (female = 15; median age = 65.36 years) received chest-CT before and after endobronchial coiling for lung volume reduction (LVR) between January 2010 and December 2014. Thin-slice (0.6 mm) non-enhanced image data sets were acquired both at end-inspiration and end-expiration using helical technique and 120 kV/100-150 mAs. Clinical response was defined as an increase in the walking distance (Six-minute walk test; 6MWT) after LVR-therapy. Additionally, pulmonary function test (PFT) measurements were used for clinical correlation. In the treated segmental bronchia, the cross-sectional lumen area showed significant reduction (p < 0.05) in inspiration and tendency towards enlargement in expiration (p > 0.05). In the ipsilateral lobes, the lumina showed no significant changes. In the contralateral lung, we found tendency towards increased cross-sectional area in inspiration (p = 0.06). Volumes of the treated segments correlated with the treated segmental bronchial lumina in expiration (r = 0.80, p < 0.001). Clinical correlation with changes in 6MWT/PFT showed a significant decrease of the inspiratory volume of the treated lobe in responders only. Endobronchial coiling causes significant decrease in the cross-sectional area of treated segment bronchi in inspiration and a slight increase in expiration accompanied by a volume reduction. • Endobronchial coiling has indirect impact on cross-sectional area of treated segment bronchi • Volume changes of treated lobes correlate with changes in bronchial cross-sectional area • Coil-induced effects reflect their stabilizing and stiffening impact on lung parenchyma • Endobronchial coiling reduces bronchial collapsing compensating the loss of elasticity.

High-resolution small field-of-view magnetic resonance image acquisition system using a small planar coil and a pneumatic manipulator in an open MRI scanner.

PubMed

Miki, Kohei; Masamune, Ken

2015-10-01

Low-field open magnetic resonance imaging (MRI) is frequently used for performing image-guided neurosurgical procedures. Intraoperative magnetic resonance (MR) images are useful for tracking brain shifts and verifying residual tumors. However, it is difficult to precisely determine the boundary of the brain tumors and normal brain tissues because the MR image resolution is low, especially when using a low-field open MRI scanner. To overcome this problem, a high-resolution MR image acquisition system was developed and tested. An MR-compatible manipulator with pneumatic actuators containing an MR signal receiver with a small radiofrequency (RF) coil was developed. The manipulator had five degrees of freedom for position and orientation control of the RF coil. An 8-mm planar RF coil with resistance and inductance of 2.04 [Formula: see text] and 1.00 [Formula: see text] was attached to the MR signal receiver at the distal end of the probe. MR images of phantom test devices were acquired using the MR signal receiver and normal head coil for signal-to-noise ratio (SNR) testing. The SNR of MR images acquired using the MR signal receiver was 8.0 times greater than that of MR images acquired using the normal head coil. The RF coil was moved by the manipulator, and local MR images of a phantom with a 2-mm grid were acquired using the MR signal receiver. A wide field-of-view MR image was generated from a montage of local MR images. A small field-of-view RF system with a pneumatic manipulator was integrated in a low-field MRI scanner to allow acquisition of both wide field-of-view and high-resolution MR images. This system is promising for image-guided neurosurgery as it may allow brain tumors to be observed more clearly and removed precisely.

Magnetic Test Facility - Sensor and Coil Calibrations

DTIC Science & Technology

2013-08-01

amplitude of signals induced into the sensor. 2.1.1.2 Fluxgate magnetometers Fluxgate sensors consist of a ferromagnetic core, around which drive and sense...kHz range to be measured. Fluxgate magnetometers do not have a lower limit to their fre- quency response, and hence can be used to measure...placed within a larger triaxial coil which is used in conjunction with a fluxgate magnetometer to cancel earth’s field at the cen- tre of the coil. A

Development of the design concepts for a medium-scale wind tunnel magnetic suspension system

NASA Technical Reports Server (NTRS)

Humphris, R. R.; Zapata, R. N.

1982-01-01

The magnitude of AC losses from a superconducting coil strongly indicates that the predicted scaling lawa are valid. The stainless steel bands around the test coil were the source of additional helium boiloff due to a transformer action and, hence, caused erroneously high AC loss measurements in the first run. However, removal of these bands for the second run produced data which are consistent with previous results on small scale multifilamentary superconducting coils.

A matrix solution for the simulation of magnetic fields with ideal current loops

NASA Technical Reports Server (NTRS)

Stankiewicz, N.

1979-01-01

A matrix formulation is presented for describing axisymmetric magnetic field data with ideal current loops. A computer program written in APL is used to invert the matrix and hence to solve for the coil strengths which are used to represent the field data. Examples are given of the coil representation for (1) measured magnetic data, (2) refocusing fields, and (3) PPM focusing fields.

A Specialized Multi-Transmit Head Coil for High Resolution fMRI of the Human Visual Cortex at 7T

PubMed Central

Sengupta, Shubharthi; Roebroeck, Alard; Kemper, Valentin G.; Poser, Benedikt A.; Zimmermann, Jan; Goebel, Rainer; Adriany, Gregor

2016-01-01

Purpose To design, construct and validate radiofrequency (RF) transmit and receive phased array coils for high-resolution visual cortex imaging at 7 Tesla. Methods A 4 channel transmit and 16 channel receive array was constructed on a conformal polycarbonate former. Transmit field efficiency and homogeneity were simulated and validated, along with the Specific Absorption Rate, using B1+ mapping techniques and electromagnetic simulations. Receiver signal-to-noise ratio (SNR), temporal SNR (tSNR) across EPI time series, g-factors for accelerated imaging and noise correlations were evaluated and compared with a commercial 32 channel whole head coil. The performance of the coil was further evaluated with human subjects through functional MRI (fMRI) studies at standard and submillimeter resolutions of upto 0.8mm isotropic. Results The transmit and receive sections were characterized using bench tests and showed good interelement decoupling, preamplifier decoupling and sample loading. SNR for the 16 channel coil was ∼ 1.5 times that of the commercial coil in the human occipital lobe, and showed better g-factor values for accelerated imaging. fMRI tests conducted showed better response to Blood Oxygen Level Dependent (BOLD) activation, at resolutions of 1.2mm and 0.8mm isotropic. Conclusion The 4 channel phased array transmit coil provides homogeneous excitation across the visual cortex, which, in combination with the dual row 16 channel receive array, makes for a valuable research tool for high resolution anatomical and functional imaging of the visual cortex at 7T. PMID:27911950

A systematic review of mosquito coils and passive emanators: defining recommendations for spatial repellency testing methodologies.

PubMed

Ogoma, Sheila B; Moore, Sarah J; Maia, Marta F

2012-12-07

Mosquito coils, vaporizer mats and emanators confer protection against mosquito bites through the spatial action of emanated vapor or airborne pyrethroid particles. These products dominate the pest control market; therefore, it is vital to characterize mosquito responses elicited by the chemical actives and their potential for disease prevention. The aim of this review was to determine effects of mosquito coils and emanators on mosquito responses that reduce human-vector contact and to propose scientific consensus on terminologies and methodologies used for evaluation of product formats that could contain spatial chemical actives, including indoor residual spraying (IRS), long lasting insecticide treated nets (LLINs) and insecticide treated materials (ITMs). PubMed, (National Centre for Biotechnology Information (NCBI), U.S. National Library of Medicine, NIH), MEDLINE, LILAC, Cochrane library, IBECS and Armed Forces Pest Management Board Literature Retrieval System search engines were used to identify studies of pyrethroid based coils and emanators with key-words "Mosquito coils" "Mosquito emanators" and "Spatial repellents". It was concluded that there is need to improve statistical reporting of studies, and reach consensus in the methodologies and terminologies used through standardized testing guidelines. Despite differing evaluation methodologies, data showed that coils and emanators induce mortality, deterrence, repellency as well as reduce the ability of mosquitoes to feed on humans. Available data on efficacy outdoors, dose-response relationships and effective distance of coils and emanators is inadequate for developing a target product profile (TPP), which will be required for such chemicals before optimized implementation can occur for maximum benefits in disease control.

Design of a Long-Stroke Noncontact Electromagnetic Actuator for Active Vibration Isolation

NASA Technical Reports Server (NTRS)

Banerjee, Bibhuti; Allaire, Paul E.

1996-01-01

A long-stroke moving coil Lorentz Actuator was designed for use in a microgravity vibration isolation experiment. The final design had a stroke of 5.08 cm (2 in) and enough force capability to isolate a mass of the order of 22.7-45.4 kg. A simple dynamic magnetic circuit analysis, using an electrical analog, was developed for the initial design of the actuator. A neodymium-iron-boron material with energy density of 278 T-kA/m (35 MGOe) was selected to supply the magnetic field. The effect of changes in the design parameters of core diameter, shell outer diameter, pole face length, and coil wire layers were investigated. An extensive three-dimensional finite element analysis was carried out to accurately determine linearity with regard to axial position of the coil and coil current levels. The actuator was constructed and tested on a universal testing machine. Example plots are shown, indicating good linearity over the stroke of approximately 5.08 cm (2 in) and a range of coil currents from -1.5 A to +1.5 A. The actuator was then used for the microgravity vibration isolation experiments, described elsewhere.

Single-coil and dual-coil defibrillator leads and association with clinical outcomes in a complete Danish nationwide ICD cohort.

PubMed

Larsen, Jacob M; Hjortshøj, Søren P; Nielsen, Jens C; Johansen, Jens B; Petersen, Helen H; Haarbo, Jens; Johansen, Martin B; Thøgersen, Anna Margrethe

2016-03-01

The best choice of defibrillator lead in patients with routine implantable cardioverter-defibrillator (ICD) is not settled. Traditionally, most physicians prefer dual-coil leads but the use of single-coil leads is increasing. The purpose of this study was to compare clinical outcomes in patients with single- and dual-coil leads. All 4769 Danish patients 18 years or older with first-time ICD implants from 2007 to 2011 were included from the Danish Pacemaker and ICD Register. Defibrillator leads were 38.9% single-coil leads and 61.1% dual-coil leads. The primary end point was all-cause mortality. Secondary end points were lowest successful energy at implant defibrillation testing, first shock failure in spontaneous arrhythmias, structural lead failure, and lead extraction outcomes. Single-coil leads were associated with lower all-cause mortality with an adjusted hazard ratio of 0.85 (95% confidence interval 0.73-0.99; P = .04). This finding was robust in a supplementary propensity score-matched analysis. However, dual-coil leads were used in patients with slightly higher preimplant morbidity, making residual confounding by indication the most likely explanation for the observed association between lead type and mortality. The lowest successful defibrillation energy was higher using single-coil leads (23.2 ± 4.3 J vs 22.1 ± 3.9 J; P < .001). No significant differences were observed for other secondary end points showing high shock efficacies and low rates of lead failures and extraction complications. Shock efficacy is high for modern ICD systems. The choice between single-coil and dual-coil defibrillator leads is unlikely to have a clinically significant impact on patient outcomes in routine ICD implants. Copyright © 2016 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.

Magnetic catheter manipulation in the interventional MR imaging environment.

PubMed

Wilson, Mark W; Martin, Alastair B; Lillaney, Prasheel; Losey, Aaron D; Yee, Erin J; Bernhardt, Anthony; Malba, Vincent; Evans, Lee; Sincic, Ryan; Saeed, Maythem; Arenson, Ronald L; Hetts, Steven W

2013-06-01

To evaluate deflection capability of a prototype endovascular catheter, which is remotely magnetically steerable, for use in the interventional magnetic resonance (MR) imaging environment. Copper coils were mounted on the tips of commercially available 2.3-3.0-F microcatheters. The coils were fabricated in a novel manner by plasma vapor deposition of a copper layer followed by laser lithography of the layer into coils. Orthogonal helical (ie, solenoid) and saddle-shaped (ie, Helmholtz) coils were mounted on a single catheter tip. Microcatheters were tested in water bath phantoms in a 1.5-T clinical MR scanner, with variable simultaneous currents applied to the coils. Catheter tip deflection was imaged in the axial plane by using a "real-time" steady-state free precession MR imaging sequence. Degree of deflection and catheter tip orientation were measured for each current application. The catheter tip was clearly visible in the longitudinal and axial planes. Magnetic field artifacts were visible when the orthogonal coils at the catheter tip were energized. Variable amounts of current applied to a single coil demonstrated consistent catheter deflection in all water bath experiments. Changing current polarity reversed the observed direction of deflection, whereas current applied to two different coils resulted in deflection represented by the composite vector of individual coil activations. Microcatheter navigation through the vascular phantom was successful through control of applied current to one or more coils. Controlled catheter deflection is possible with laser lithographed multiaxis coil-tipped catheters in the MR imaging environment. Copyright © 2013 SIR. Published by Elsevier Inc. All rights reserved.

An Asymmetric Birdcage Coil for Small-animal MR Imaging at 7T

PubMed Central

Kim, Kyoung-Nam; Han, Sang-Doc; Seo, Jeung-Hoon; Heo, Phil; Yoo, Dongkyeom; Im, Geun Ho; Lee, Jung Hee

2017-01-01

The birdcage (BC) coil is currently being utilized for uniform radiofrequency (RF) transmit/receive (Tx/Rx) or Tx-only configuration in many magnetic resonance (MR) imaging applications, but insufficient magnetic flux (|B1|) density and their non-uniform distribution still exists in high-field (HF) environments. We demonstrate that the asymmetric birdcage (ABC) transmit/receive (Tx/Rx) volume coil, which is a modified standard birdcage (SBC) coil with the end ring split into two halves, is suitable for improving the |B1| sensitivity in 7T small-animal MR imaging. Cylindrical SBC and ABC coils with 35 mm diameter were constructed and bench tested for mouse body MR imaging at 300 MHz using a 7T scanner. To assess the ABC coil performance, computational electromagnetic (EM) simulation and 7T MR experiment were performed by using a cylindrical phantom and in vivo mouse body and quantitatively compared with the SBC coil in terms of |B1| distribution, RF transmit (|B1+|) field, and signal-to-noise ratio (SNR). The bench measurements of the two BC coils are similar, yielding a quality value (Q-value) of 74.42 for the SBC coil and 77.06 for the ABC coil. The computational calculation results clearly show that the proposed ABC coil offers superior |B1| field and |B1+| field sensitivity in the central axial slice compared with the SBC coil. There was also high SNR and uniformly distributed flip angle (FA) under the loaded condition of mouse body in the 7T experiment. Although ABC geometry allows a further increase in the |B1| field and |B1+| field sensitivity in only the central axial slice, the geometrical modification of the SBC coil can make a high performance RF coil feasible in the central axial slice and also make target imaging possible in the diagonal direction. PMID:27725573

Healing of Saccular Aneurysms Following Platinum Coil Embolization: Lack of Improved Efficacy with Vitamin C Supplementation

PubMed Central

Dai, Daying; Ding, Yong-Hong; Rezek, Issa; Lewis, Debra A.; Kallmes, David F.; Kadirvel, Ramanathan

2013-01-01

BACKGROUND AND PURPOSE To test the hypothesis that systemic administration of vitamin C, through its action of stimulating collagen synthesis and cross-linking, would decrease the recurrence and improve the occlusion experimental aneurysms treated with platinum coil embolization. METHODS Nineteen experimental aneurysms in female rabbits were embolized with platinum coils (>30% packing density). The animals were divided into three groups: Group 1 (n=6) rabbits served as controls, Group 2 (n=5) rabbits were fed with a vitamin C-supplemented feed and Group 3 (n=8) rabbits were medicated with vitamin C pills. Digital subtraction angiography was used to evaluate stability after embolization. Subjects were euthanized at 12 weeks after coil implantation, and serum vitamin C levels were then measured. Histological samples were examined with a grading system (range, 0-12) based on the neck and dome features. Masson Trichrome staining was employed to evaluate collagen deposition. Parametric data were analyzed with one-way analysis of variance and non-parametric data were examined using a Kruskal-Wallis test. RESULTS There were no significant differences between groups in mean aneurysm size. Mean serum vitamin C concentration was significantly higher in Group 3 and Group 2 compared to Group 1, while vitamin C levels between Group 2 and Group 3 were statistically comparable. Coil compaction was noted in one of six subjects in Group 1 and three of eight subjects in Group 3. All the remaining aneurysms in the test and control groups showed stable occlusion. There were no significant differences in histological scores or collagen deposition among groups. CONCLUSION Vitamin C supplementation following platinum coil embolization does not demonstrate improvement of long-term occlusion rates of aneurysms. PMID:22914744

Healing of saccular aneurysms following platinum coil embolization: lack of improved efficacy with vitamin C supplementation.

PubMed

Dai, Daying; Yong-Hong, Ding; Rezek, Issa; Lewis, Debra A; Kallmes, David F; Kadirvel, Ramanathan

2013-11-01

To test the hypothesis that systemic administration of vitamin C, through its action of stimulating collagen synthesis and crosslinking, would decrease the recurrence and improve the occlusion of experimental aneurysms treated with platinum coils. Experimental aneurysms were created in female rabbits and were embolized with platinum coils (>30% packing density). The animals were divided into three groups: group 1 (n=6) rabbits served as controls, group 2 (n=5) rabbits were fed with a vitamin C supplemented feed and group 3 (n=8) rabbits were medicated with vitamin C pills. Digital subtraction angiography was used to evaluate stability after embolization. Subjects were euthanized at 12 weeks after coil implantation, and serum vitamin C levels were then measured. Histological samples were examined with a grading system (range 0-12) based on the neck and dome features. Masson Trichrome staining was used to evaluate collagen deposition. Parametric data were analyzed with one way analysis of variance and non-parametric data were examined using a Kruskal-Wallis test. There were no significant differences between groups in mean aneurysm size. Mean serum vitamin C concentration was significantly higher in group 3 and group 2 compared with group 1, while vitamin C levels between group 2 and group 3 were statistically comparable. Coil compaction was noted in one of six subjects in group 1 and in three of eight subjects in group 3. All of the remaining aneurysms in the test and control groups showed stable occlusion. There were no significant differences in histological scores or collagen deposition among groups. Vitamin C supplementation following platinum coil embolization does not demonstrate improvement of long term occlusion rates of aneurysms.

Demonstration of a Conduction Cooled React and Wind MgB2 Coil Segment for MRI Applications

PubMed Central

Kim, H. S.; Kovacs, C.; Rindfleisch, M.; Yue, J.; Doll, D.; Tomsic, M.; Sumption, M. D.; Collings, E. W.

2016-01-01

This study is a contribution to the development of technology for an MgB2-based, cryogen-free, superconducting magnet for an MRI system. Specifically, we aim to demonstrate that a react and wind coil can be made using high performance in-situ route MgB2 conductor, and that the conductor could be operated in conduction mode with low levels of temperature gradient. In this work, an MgB2 conductor was used for the winding of a sub-size, MRI-like coil segment. The MgB2 coil was wound on a 457 mm ID 101 OFE copper former using a react-and-wind approach. The total length of conductor used was 330 m. The coil was epoxy impregnated and then instrumented for low temperature testing. After the initial cool down (conduction cooling) the coil Ic was measured as a function of temperature (15-30 K), and an Ic of 200 A at 15 K was measured. PMID:27857508

Portable wireless power transmission system for video capsule endoscopy.

PubMed

Zhiwei, Jia; Guozheng, Yan; Bingquan, Zhu

2014-10-01

Wireless power transmission is considered a practical way of overcoming the power shortage of wireless capsule endoscopy (VCE). However, most patients cannot tolerate the long hours of lying in a fixed transmitting coil during diagnosis. To develop a portable wireless power transmission system for VCE, a compact transmitting coil and a portable inverter circuit driven by rechargeable batteries are proposed. The couple coils, optimized considering the stability and safety conditions, are 28 turns of transmitting coil and six strands of receiving coil. The driven circuit is designed according to the portable principle. Experiments show that the integrated system could continuously supply power to a dual-head VCE for more than 8 h at a frame rate of 30 frames per second with resolution of 320 × 240. The portable VCE exhibits potential for clinical applications, but requires further improvement and tests.

Initial design of 12S-10P outer-rotor field excitation flux switching motor with different rotor width

NASA Astrophysics Data System (ADS)

Othman, Syed Muhammad Naufal bin Syed; Sulaiman, Erwan bin; Husin, Zhafir Aizat; Khan, Faisal; Mazlan, Mohamed Mubin Aizat

2015-05-01

This paper proposes an initial design of 12 slot, 10 pole outer-rotor field-excitation flux switching motor (FEFSM) with two different rotor width based from 2 different formula to design the rotor width. Hence, initial design include the three coil test to determine the U, W, V-phase, the flux strengthening and weakening, flux at various armature coil and field-excitation coil current, and finally the torque at various JA and JE. As for the materials, the stator and rotor consists of steel sheets made of electromagnetic steels, copper for armature coils and field excitation coils as the only field for magnetic flux source. There will be some design specification and restriction on outer-rotor FEFSM based on 2D-Finite Element Analysis will be applied to design the proposed machine.

Finite Difference Time Domain Modeling at USA Instruments, Inc.

NASA Astrophysics Data System (ADS)

Curtis, Richard

2003-10-01

Due to the competitive nature of the commercial MRI industry, it is essential for the financial health of a participating company to innovate new coil designs and bring product to market rapidly in response to ever-changing market conditions. However, the technology of MRI coil design is still early in its stage of development and its principles are yet evolving. As a result, it is not always possible to know the relevant electromagnetic effects of a given design since the interaction of coil elements is complex and often counter-intuitive. Even if the effects are known qualitatively, the quantitative results are difficult to obtain. At USA Instruments, Inc., the acquisition of the XFDTDâ electromagnetic simulation tool from REMCOM, Inc., has been helpful in determining the electromagnetic performance characteristics of existing coil designs in the prototype stage before the coils are released for production. In the ideal case, a coil design would be modeled earlier at the conceptual stage, so that only good designs will make it to the prototyping stage and the electromagnetic characteristics better understood very early in the design process and before the testing stage has begun. This paper is a brief overview of using FDTD modeling for MRI coil design at USA Instruments, Inc., and shows some of the highlights of recent FDTD modeling efforts on Birdcage coils, a staple of the MRI coil design portfolio.

Computational fluid dynamics (CFD) using porous media modeling predicts recurrence after coiling of cerebral aneurysms.

PubMed

Umeda, Yasuyuki; Ishida, Fujimaro; Tsuji, Masanori; Furukawa, Kazuhiro; Shiba, Masato; Yasuda, Ryuta; Toma, Naoki; Sakaida, Hiroshi; Suzuki, Hidenori

2017-01-01

This study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD). A total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s. Follow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P < 0.05). Among the hemodynamic parameters, aneurysms in the recurrence group had significantly larger inflow and outflow areas in the control CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01-1.11; P = 0.016). The study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms.

SU-F-J-153: ACR MRI Phantom Test On a 1.5T MR-Simulator with Flexible Coils Setting and Performance Comparison to Volumetric Head Coil Setting

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

Yuan, J; Wong, O; Cheung, K

Purpose: To accommodate head-and-neck (HN) RT simulation scan with immobilization, sub-optimized flexible radiofrequency coils have to be used on an MR-sim rather than a volumetric head coil for diagnostic radiological (DR) applications. In this study, we present and compare ACR MRI phantom test with flexible coils setting (RT-setting) and volumetric head coil setting (DR-setting). Methods: Two 8-channel array coils were wrapped close to an ACR MRI phantom placed on a flat couch-top in RT-setting for acquisition. ACR MRI phantom tests were conducted 10 times for each setting on a 1.5T MR-sim. Sagittal localizer (TE/TR=20/200ms), axial T1 (TE/TR=20/500ms) and T2 scansmore » (2TEs/TR=20,80/2000ms) were acquired (NEX=1). Acqusition and image analysis were conducted following ACR guidelines. Extra 10 RT-setting acquisitions were obtained by enabling prescan normalization. Results: For RT-setting without prescan normalization, all tests passed the ACR recommended criteria but image intensity uniformity. Geometric accuracy was 147.8±0.3mm and 191.0±0.4mm. Spatial resolution was 0.9mm. Slice thickness was 5.2mm±0.1mm (T1) and 5.1±0.1mm (T2). Slice position accuracy was 1.4±0.6mm, −2.2±0.3mm (T1), and 1.5±0.2mm, −2.2±0.2mm (T2). Image uniformity was 80.6%±2.6% (T1) and 80.2%±3.1% (T2) (criteria: ≥87.5% for 1.5T). Ghosting ratio was 0.0006±0.0004. Low contrast detectability was 30.7±1.7 (T1) and 22.6±3.0 (T2). Image uniformity (91.4%±4.2% and 91.8%±4.3%) and low contrast detectability (36.5±1.4 and 31.6±2.2) of DR-setting were better than RT-setting. Prescan normalization substantially improved image uniformity to 93.4%±0.2% and 93.4%±0.3%, but slightly compromised ghosting (0.0033±0.0004) and spatial resolution (0.9mm or 1.0mm) for RT-setting. Conclusion: Flexible coils setting for HN-RT simulation scan could successfully pass ACR criteria (prescan normalization enabled) and generally achieve comparable performance to volumetric coil setting, although compromise on low contrast detectability was observed probably due to the lower signal-to-noise ratio of the flexible coils. Our results could also serve as a reference baseline of high-field MR-sim QA performance under ACR guideline.« less

Testing military grade magnetics (transformers, inductors and coils).

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

Not Available

Engineers and designers are constantly searching for test methods to qualify or 'prove-in' new designs. In the High Reliability world of military parts, design test, qualification tests, in process tests and product characteristic tests, become even more important. The use of in process and function tests has been adopted as a way of demonstrating that parts will operate correctly and survive its 'use' environments. This paper discusses various types of tests to qualify the magnetic components - the current carrying capability of coils, a next assembly 'as used' test, a corona test and inductance at temperature test. Each of thesemore » tests addresses a different potential failure on a component. The entire process from design to implementation is described.« less

Summary of the 2012 Inductive Pulsed Plasma Thruster Development and Testing Program

NASA Technical Reports Server (NTRS)

Polzin, K. A.; Martin, A. K.; Eskridge, R. H.; Kimberlin, A. C.; Addona, B. M.; Devineni, A. P.; Dugal-Whitehead, N. R.; Hallock, A. K.

2013-01-01

Inductive pulsed plasma thrusters are spacecraft propulsion devices in which energy is capacitively stored and then discharged through an inductive coil. While these devices have shown promise for operation at high efficiency on a range of propellants, many technical issues remain before they can be used in flight applications. A conical theta-pinch thruster geometry was fabricated and tested to investigate potential improvements in propellant utilization relative to more common, flat-plate planar coil designs. A capacitor charging system is used to permit repetitive discharging of thrusters at multiple cycles per second, with successful testing accomplished at a repetition-rate of 5 Hz at power levels of 0.9, 1.6, and 2.5 kW. The conical theta-pinch thruster geometry was tested at cone angles of 20deg, 38deg, and 60deg, with single-pulse operation at 500 J/pulse and repetitionrate operation with the 38deg model quantified through direct thrust measurement using a hanging pendulum thrust stand. A long-lifetime valve was designed and fabricated, and initial testing was performed to measure the valve response and quantify the leak rate at beginning-of-life. Subscale design and testing of a capacitor charging system required for operation on a spacecraft is reported, providing insights into the types of components needed in the circuit topology employed. On a spacecraft, this system would accept as input a lower voltage from the spacecraft DC bus and boost the output to the high voltage required to charge the capacitors of the thruster.

REPPER—repeats and their periodicities in fibrous proteins

PubMed Central

Gruber, Markus; Söding, Johannes; Lupas, Andrei N.

2005-01-01

REPPER (REPeats and their PERiodicities) is an integrated server that detects and analyzes regions with short gapless repeats in protein sequences or alignments. It finds periodicities by Fourier Transform (FTwin) and internal similarity analysis (REPwin). FTwin assigns numerical values to amino acids that reflect certain properties, for instance hydrophobicity, and gives information on corresponding periodicities. REPwin uses self-alignments and displays repeats that reveal significant internal similarities. Both programs use a sliding window to ensure that different periodic regions within the same protein are detected independently. FTwin and REPwin are complemented by secondary structure prediction (PSIPRED) and coiled coil prediction (COILS), making the server a versatile analysis tool for sequences of fibrous proteins. REPPER is available at . PMID:15980460

DESIGN OF SUPERCONDUCTING COMBINED FUNCTION MAGNETS FOR THE 50 GEV PROTON BEAM LINE FOR THE J-PARC NEUTRINO EXPERIMENT.

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

WANDERER,P.; ET AL.

2003-06-15

Superconducting combined function magnets will be utilized for the 50GeV-750kW proton beam line for the J-PARC neutrino experiment and an R and D program has been launched at KEK. The magnet is designed to provide a combined function with a dipole field of 2.59 T and a quadrupole field of 18.7 T/m in a coil aperture of 173.4 mm. A single layer coil is proposed to reduce the fabrication cost and the coil arrangement in the 2-D cross-section results in left-right asymmetry. This paper reports the design study of the magnet.

A 31-Channel MR Brain Array Coil Compatible with Positron Emission Tomography

PubMed Central

Sander, Christin Y.; Keil, Boris; Chonde, Daniel B.; Rosen, Bruce R.; Catana, Ciprian; Wald, Lawrence L.

2014-01-01

Purpose Simultaneous acquisition of MR and PET images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. Methods A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (SNR, g-factor) and PET attenuation. Results The coil design showed an improvement in attenuation by 190% (average) compared to conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical ROI) compared to a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. Conclusion The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. PMID:25046699

Theoretical analysis of the electrical aspects of the basic electro-impulse problem in aircraft de-icing applications

NASA Technical Reports Server (NTRS)

Henderson, R. A.; Schrag, R. L.

1986-01-01

A summary of modeling the electrical system aspects of a coil and metal target configuration resembling a practical electro-impulse deicing (EIDI) installation, and a simple circuit for providing energy to the coil, was presented. The model was developed in sufficient theoretical detail to allow the generation of computer algorithms for the current in the coil, the magnetic induction on both surfaces of the target, the force between the coil and target, and the impulse delivered to the target. These algorithms were applied to a specific prototype EIDI test system for which the current, magnetic fields near the target surfaces, and impulse were previously measured.

Geometrical analysis on cap-shaped coils for power optimization of the vibration-based electromagnetic harvesting system

NASA Astrophysics Data System (ADS)

Hasbullah Mohd Isa, Wan; Fikri Muhammad, Khairul; Mohd Khairuddin, Ismail; Ishak, Ismayuzri; Razlan Yusoff, Ahmad

2016-02-01

This paper presents the new form of coils for electromagnetic energy harvesting system based on topology optimization method which look-liked a cap to maximize the power output. It could increase the number of magnetic flux linkage interception of a cylindrical permanent magnet which in this case is of 10mm diameter. Several coils with different geometrical properties have been build and tested on a vibration generator with frequency of 100Hz. The results showed that the coil with lowest number of winding transduced highest power output of 680μW while the highest number of windings generated highest voltage output of 0.16V.

Effect of temperature on the orthodontic clinical applications of niti closed-coil springs

PubMed Central

Espinar-Escalona, Eduardo; Llamas-Carreras, José M.; Barrera-Mora, José M.; Abalos-Lasbrucci, Camilo

2013-01-01

NiTi spring coils were used to obtain large deformation under a constant force. The device consists on a NiTi coil spring, superelastic at body temperature, in order to have a stress plateau during the austenitic retransformation during the unloading. The temperature variations induced changes in the spring force. Objectives: The aim of this study is to investigate the effect of the temperature variations in the spring forces and corrosion behaviour simulating the ingestion hot/cold drinks and food. Study Design: The springs were subjected to a tensile force using universal testing machine MTS-Adamel (100 N load cell). All tests were performed in artificial saliva maintained at different temperatures. The corrosion tests were performed according to the ISO-standard 10993-15:2000. Results: The increase in temperature of 18oC induced an increase in the spring force of 30%. However, when the temperature returns to 37oC the distraction force recovers near the initial level. After cooling down the spring to 15oC, the force decreased by 46%. This investigation show as the temperature increase, the corrosion potential shifts towards negative values and the corrosion density is rising. Conclusions: The changes of the temperatures do not modify the superelastic behaviour of the NiTi closed-coil springs. The corrosion potential of NiTi in artificial saliva is decreasing by the rise of the temperatures. Key words:Superelasticity, NiTi, springs, orthodontic, coils, recovery, temperature. PMID:23722142

Design and prototype fabrication of a 30 tesla cryogenic magnet

NASA Technical Reports Server (NTRS)

Prok, G. M.; Swanson, M. C.; Brown, G. V.

1977-01-01

A liquid-neon-cooled magnet has been designed to produce 30 teslas in steady operation. Its feasibility was established by a previously reported parametric study. To ensure the correctness of the heat transfer relationships used, supercritical neon heat transfer tests were made. Other tests made before the final design included tests on the effect of the magnetic field on pump motors; tensile-shear tests on the cryogenic adhesives; and simulated flow studies for the coolant. The magnet will be made of two pairs of coils, cooled by forced convection of supercritical neon. Heat from the supercritical neon will be rejected through heat exchangers which are made of roll-bonded copper panels and are submerged in a pool of saturated liquid neon. A partial mock-up coil was wound to identify the tooling required to wind the magnet. This was followed by winding a prototype pair of coils. The prototype winding established procedures for fabricating the final magnet and revealed slight changes needed in the final design.

Portal vein embolization with plug/coils improves hepatectomy outcome.

PubMed

Malinowski, Maciej; Geisel, Dominik; Stary, Victoria; Denecke, Timm; Seehofer, Daniel; Jara, Maximillian; Baron, Annekathrin; Pratschke, Johann; Gebauer, Bernhard; Stockmann, Martin

2015-03-01

Portal vein embolization (PVE) has become the standard of care before extended hepatectomy. Various PVE methods using different embolization materials have been described. In this study, we compared PVE with polyvinyl alcohol particles alone (PVA only) versus PVA with plug or coils (PVA + plug/coils). Patients undergoing PVE before hepatectomy were included. PVA alone was used until December 2013, thereafter plug or coils were placed in addition. The volume of left lateral liver lobe (LLL), clinical parameters, and liver function tests were measured before PVE and resection. A total of 43 patients were recruited into the PVA only group and 42 were recruited into the PVA + plug/coils group. There were no major differences between groups except significantly higher total bilirubin level before PVE in the PVA only group, which improved before hepatectomy. Mean LLL volume increased by 25.7% after PVE in the PVA only group and by 44% in the PVA + plug/coils group (P < 0.001). Recanalization was significantly less common in the PVA + plug/coils group. In multivariate regression, initial LLL volume and use of plug or coils were the only parameters influencing LLL volume increase. The postoperative liver failure rate was significantly reduced in PVA + plug/coils group (P = <0.001). PVE using PVA particles together with plug or coils is a safe and efficient method to increase future liver remnant volume. The additional central embolization with plug or coils led to an increased hypertrophy, due to lower recanalization rates, and subsequently decreased incidence of postoperative liver failure. No additional procedure-specific complications were observed in this series. Copyright © 2015 Elsevier Inc. All rights reserved.

[Surface coils for magnetic-resonance images].

PubMed

Rodríguez-González, Alfredo Odón; Amador-Baheza, Ricardo; Rojas-Jasso, Rafael; Barrios-Alvarez, Fernando Alejandro

2005-01-01

Since the introduction of magnetic resonance imaging in Mexico, the development of this important medical imaging technology has been almost non-existing in our country. The very first surface coil prototypes for clinical applications in magnetic resonance imaging has been developed at the Center of Research in Medical Imaging and Instrumentation of the Universidad Autónoma Metropolitana Iztapalapa (Metropolitan Autonomous University, Campus Iztapalapa). Two surface coil prototypes were built: a) a circular-shaped coil and b) a square-shaped coil for multiple regions of the body, such as heart, brain, knee, hands, and ankles. These coils were tested on the 1.5T imager of the ABC Hospital-Tacubaya, located in Mexico City. Brain images of healthy volunteers were obtained in different orientations: sagittal, coronal, and axial. Since images showed a good-enough clinical quality for diagnosis, it is fair to say that these coil prototypes can be used in the clinical environment, and with small modifications, they can be made compatible with almost any commercial scanner. This type of development can offer new alternatives for further collaboration between the research centers and the radiology community, in the search of new applications and developments of this imaging technique.

LDRD final report on confinement of cluster fusion plasmas with magnetic fields.

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

Argo, Jeffrey W.; Kellogg, Jeffrey W.; Headley, Daniel Ignacio

2011-11-01

Two versions of a current driver for single-turn, single-use 1-cm diameter magnetic field coils have been built and tested at the Sandia National Laboratories for use with cluster fusion experiments at the University of Texas in Austin. These coils are used to provide axial magnetic fields to slow radial loss of electrons from laser-produced deuterium plasmas. Typical peak field strength achievable for the two-capacitor system is 50 T, and 200 T for the ten-capacitor system. Current rise time for both systems is about 1.7 {mu}s, with peak current of 500 kA and 2 MA, respectively. Because the coil must bemore » brought to the laser, the driver needs to be portable and drive currents in vacuum. The drivers are complete but laser-plasma experiments are still in progress. Therefore, in this report, we focus on system design, initial tests, and performance characteristics of the two-capacitor and ten-capacitors systems. The questions of whether a 200 T magnetic field can retard the breakup of a cluster-fusion plasma, and whether this field can enhance neutron production have not yet been answered. However, tools have been developed that will enable producing the magnetic fields needed to answer these questions. These are a two-capacitor, 400-kA system that was delivered to the University of Texas in 2010, and a 2-MA ten-capacitor system delivered this year. The first system allowed initial testing, and the second system will be able to produce the 200 T magnetic fields needed for cluster fusion experiments with a petawatt laser. The prototype 400-kA magnetic field driver system was designed and built to test the design concept for the system, and to verify that a portable driver system could be built that delivers current to a magnetic field coil in vacuum. This system was built copying a design from a fixed-facility, high-field machine at LANL, but made to be portable and to use a Z-machine-like vacuum insulator and vacuum transmission line. This system was sent to the University of Texas in Austin where magnetic fields up to 50 T have been produced in vacuum. Peak charge voltage and current for this system have been 100 kV and 490 kA. It was used this last year to verify injection of deuterium and surrogate clusters into these small, single-turn coils without shorting the coil. Initial test confirmed the need to insulate the inner surface of the coil, which requires that the clusters must be injected through small holes in an insulator. Tests with a low power laser confirmed that it is possible to inject clusters into the magnetic field coils through these holes without destroying the clusters. The university team also learned the necessity of maintaining good vacuum to avoid insulator, transmission line, and coil shorting. A 200-T, 2 MA system was also constructed using the experience from the first design to make the pulsed-power system more robust. This machine is a copy of the prototype design, but with ten 100-kV capacitors versus the two used in the prototype. It has additional inductance in the switch/capacitor unit to avoid breakdown seen in the prototype design. It also has slightly more inductance at the cable connection to the vacuum chamber. With this design we have been able to demonstrate 1 MA current into a 1 cm diameter coil with the vacuum chamber at air pressure. Circuit code simulations, including the additional inductance with the new design, agree well with the measured current at a charge voltage of 40 kV with a short circuit load, and at 50 kV with a coil. The code also predicts that with a charge voltage of 97 kV we will be able to get 2 MA into a 1 cm diameter coil, which will be sufficient for 200 T fields. Smaller diameter or multiple-turn coils will be able to achieve even higher fields, or be able to achieve 200-T fields with lower charge voltage. Work is now proceeding at the university under separate funding to verify operation at the 2-MA level, and to address issues of debris mitigation, measurement of the magnetic field, and operation in vacuum. We anticipate operation at full current with single-turn, magnetic field coils this fall, with 200 T experiments on the Texas Petawatt laser in the spring of 2012.« less

Development of an YBCO coil with SSTC conductors for high field application

NASA Astrophysics Data System (ADS)

Shi, Y.; Liu, H. J.; Liu, F.; Tan, Y. F.; Jin, H.; Yu, M.; Lei, L.; Guo, L.; Hong, Z. Y.

2018-07-01

With the continuous reduction of the production costs and improvement of the transport performance, YBCO coated conductor is the most promising candidate for the high field magnet application due to its high irreversibility field and strong mechanical properties. Presently a stable production capacity of the YBCO conductors has been achieved by Shanghai Superconducting Technology Co., Ltd (SSTC) in China. Therefore, the demand in high field application with YBCO conductors is growing in China. This paper describes the design, fabrication and preliminary experiment of a solenoid coil with YBCO conductors supplied by SSTC to validate the possibility of high field application. Four same double pancakes were manufactured and assembled for the YBCO coil where the outer diameter and height was 54.3 and 48 mm respectively to match the dimensional limitation of the 14 T background magnets. The critical current (Ic) of YBCO conductors was obtained by measuring as a function of the applied field perpendicular to the YBCO conductor surface which provides the necessary input parameters for preliminary performance evaluation of the coil. Finally the preliminary test and discussion at 77 and 4.2 K were carried out. The consistency of four double pancakes Ic was achieved. The measured results indicate that the fabrication technology of HTS coil is reliable which gives the conference for the in-field test in high field application. This YBCO coil is the first demonstration of the SSTC YBCO coated conductors.

Metal-as-insulation variant of no-insulation HTS winding technique: pancake tests under high background magnetic field and high current at 4.2 K

NASA Astrophysics Data System (ADS)

Lécrevisse, T.; Badel, A.; Benkel, T.; Chaud, X.; Fazilleau, P.; Tixador, P.

2018-05-01

In the framework of a project aiming at fabricating a 10 T high temperature superconducting (HTS) insert to operate in a 20 T background field, we are investigating the behavior of pancakes consisting of a REBCO HTS tape co-wound with a stainless steel tape (metal-as-insulation (MI) coil). The MI winding is inducing a significant turn-to-turn electrical resistance which helps to reduce the charging time delay. Despite this resistance, the self-protection feature of no-insulation coils is still enabled, thanks to the voltage limit of the power supply. We have built a single pancake coil representative of the pancake that will be used in the insert and performed tests under very high background magnetic field. Our coil experienced over 100 heater induced quenches without a measureable increase of its internal resistance. We have gathered stability and quench behavior data for magnetic fields and engineering current densities (je ) in the range of 0–17 T and 0–635 A mm‑2 respectively. We also present our very first experiments on the insert/outsert interaction in the case of a resistive magnet fault. We show that if self-protection of the MI winding is really effective in the case of a MI coil quench, a major issue comes from the outsert fault which induces a huge current inside the MI coil.

Split gradient coils for simultaneous PET-MRI

PubMed Central

Poole, Michael; Bowtell, Richard; Green, Dan; Pittard, Simon; Lucas, Alun; Hawkes, Rob; Carpenter, Adrian

2015-01-01

Combining positron emission tomography (PET) and MRI necessarily involves an engineering tradeoff as the equipment needed for the two modalities vies for the space closest to the region where the signals originate. In one recently described scanner configuration for simultaneous positron emission tomography–MRI, the positron emission tomography detection scintillating crystals reside in an 80-mm gap between the 2 halves of a 1-T split-magnet cryostat. A novel set of gradient and shim coils has been specially designed for this split MRI scanner to include an 110-mm gap from which wires are excluded so as not to interfere with positron detection. An inverse boundary element method was necessarily employed to design the three orthogonal, shielded gradient coils and shielded Z0 shim coil. The coils have been constructed and tested in the hybrid positron emission tomography-MRI system and successfully used in simultaneous positron emission tomography-MRI experiments. PMID:19780167

Deep Brain Stimulation using Magnetic Fields

NASA Astrophysics Data System (ADS)

Jiles, David; Williams, Paul; Crowther, Lawrence; Iowa State University Team; Wolfson CentreMagnetics Team

2011-03-01

New applications for transcranial magnetic stimulation are developing rapidly for both diagnostic and therapeutic purposes. Therefore so is the demand for improved performance, particularly in terms of their ability to stimulate deeper regions of the brain and to do so selectively. The coil designs that are used presently are limited in their ability to stimulate the brain at depth and with high spatial focality. Consequently, any improvement in coil performance would have a significant impact in extending the usefulness of TMS in both clinical applications and academic research studies. New and improved coil designs have then been developed, modeled and tested as a result of this work. A large magnetizing coil, 300mm in diameter and compatible with a commercial TMS system has been constructed to determine its feasibility for use as a deep brain stimulator. The results of this work have suggested directions that could be pursued in order to further improve the coil designs.

Transcutaneous RF-Powered Implantable Minipump Driven by a Class-E Transmitter

PubMed Central

Moore, William H.; Holschneider, Daniel P.; Givrad, Tina K.

2007-01-01

We describe the design and testing of an inductive coupling system used to power an implantable minipump for applications in ambulating rats. A 2 MHz class-E oscillator driver powered a coil transmitter wound around a 33-cm-diameter rat cage. A receiver coil, a filtered rectifier, and a voltage-sensitive switch powered the implant. The implant DC current at the center of the primary coil (5.1 V) exceeded the level required to activate the solenoid valve in the pump. The variations of the implant current in the volume of the primary coil reflected the variations of the estimated coupling coefficient between the two coils. The pump could be activated in-vivo, while accommodating the vertical and horizontal movements of the animal. Advantages of this design include a weight reduction for the implant, an operation independent from a finite power source, and a remote activation/deactivation. PMID:16916107

Transcutaneous RF-powered implantable minipump driven by a class-E transmitter.

PubMed

Moore, William H; Holschneider, Daniel P; Givrad, Tina K; Maarek, Jean-Michel I

2006-08-01

We describe the design and testing of an inductive coupling system used to power an implantable minipump for applications in ambulating rats. A 2 MHz class-E oscillator driver powered a coil transmitter wound around a 33-cm-diameter rat cage. A receiver coil, a filtered rectifier, and a voltage-sensitive switch powered the implant. The implant DC current at the center of the primary coil (5.1 V) exceeded the level required to activate the solenoid valve in the pump. The variations of the implant current in the volume of the primary coil reflected the variations of the estimated coupling coefficient between the two coils. The pump could be activated in-vivo, while accommodating the vertical and horizontal movements of the animal. Advantages of this design include a weight reduction for the implant, an operation independent from a finite power source, and a remote activation/deactivation.

Electrical and thermal characteristics of Bi2212/Ag HTS coils for conduction-cooled SMES

NASA Astrophysics Data System (ADS)

Hayakawa, N.; Noguchi, S.; Kurupakorn, C.; Kojima, H.; Endo, F.; Hirano, N.; Nagaya, S.; Okubo, H.

2006-06-01

In this paper, we investigated the electrical and thermal performance of conduction-cooled Bi2212/Ag HTS coils with 4K-GM cryocooler system. First, we measured the critical current Ic for different ambient temperatures T0 at 4.2 K - 40 K. Experimental results revealed that Ic increased with the decrease in T0 and was saturated at T0 < 10 K. We carried out thermal analysis considering heat generation, conduction and transfer under conduction-cooling condition, and reproduced the electrical and thermal characteristics of the conduction-cooled HTS coil, taking account of temperature dependence of specific heat and thermal conductivity of the materials. We also measured the temperature rise of Bi2212/Ag HTS coil for different continuous current levels at T0 = 4.8 K. Experimental results revealed the criterion of thermal runaway, which was discussed in terms of heat generation and propagation in the test coil.

Summary of Test Results of MQXFS1 - The First Short Model 150 mm Aperture $$Nb_3Sn$$ Quadrupole for the High-Luminosity

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

Stoynev, S.; et al.

The development ofmore » $$Nb_3Sn$$ quadrupole magnets for the High-Luminosity LHC upgrade is a joint venture between the US LHC Accelerator Research Program (LARP)* and CERN with the goal of fabricating large aperture quadrupoles for the LHC in-teraction regions (IR). The inner triplet (low-β) NbTi quadrupoles in the IR will be replaced by the stronger Nb3Sn magnets boosting the LHC program of having 10-fold increase in integrated luminos-ity after the foreseen upgrades. Previously LARP conducted suc-cessful tests of short and long models with up to 120 mm aperture. The first short 150 mm aperture quadrupole model MQXFS1 was assembled with coils fabricated by both CERN and LARP. The magnet demonstrated strong performance at the Fermilab’s verti-cal magnet test facility reaching the LHC operating limits. This paper reports the latest results from MQXFS1 tests with changed pre-stress levels. The overall magnet performance, including quench training and memory, ramp rate and temperature depend-ence, is also summarized.« less

Dynamic performance of high speed solenoid valve with parallel coils

NASA Astrophysics Data System (ADS)

Kong, Xiaowu; Li, Shizhen

2014-07-01

The methods of improving the dynamic performance of high speed on/off solenoid valve include increasing the magnetic force of armature and the slew rate of coil current, decreasing the mass and stroke of moving parts. The increase of magnetic force usually leads to the decrease of current slew rate, which could increase the delay time of the dynamic response of solenoid valve. Using a high voltage to drive coil can solve this contradiction, but a high driving voltage can also lead to more cost and a decrease of safety and reliability. In this paper, a new scheme of parallel coils is investigated, in which the single coil of solenoid is replaced by parallel coils with same ampere turns. Based on the mathematic model of high speed solenoid valve, the theoretical formula for the delay time of solenoid valve is deduced. Both the theoretical analysis and the dynamic simulation show that the effect of dividing a single coil into N parallel sub-coils is close to that of driving the single coil with N times of the original driving voltage as far as the delay time of solenoid valve is concerned. A specific test bench is designed to measure the dynamic performance of high speed on/off solenoid valve. The experimental results also prove that both the delay time and switching time of the solenoid valves can be decreased greatly by adopting the parallel coil scheme. This research presents a simple and practical method to improve the dynamic performance of high speed on/off solenoid valve.

Computational fluid dynamics (CFD) using porous media modeling predicts recurrence after coiling of cerebral aneurysms

PubMed Central

Ishida, Fujimaro; Tsuji, Masanori; Furukawa, Kazuhiro; Shiba, Masato; Yasuda, Ryuta; Toma, Naoki; Sakaida, Hiroshi; Suzuki, Hidenori

2017-01-01

Objective This study aimed to predict recurrence after coil embolization of unruptured cerebral aneurysms with computational fluid dynamics (CFD) using porous media modeling (porous media CFD). Method A total of 37 unruptured cerebral aneurysms treated with coiling were analyzed using follow-up angiograms, simulated CFD prior to coiling (control CFD), and porous media CFD. Coiled aneurysms were classified into stable or recurrence groups according to follow-up angiogram findings. Morphological parameters, coil packing density, and hemodynamic variables were evaluated for their correlations with aneurysmal recurrence. We also calculated residual flow volumes (RFVs), a novel hemodynamic parameter used to quantify the residual aneurysm volume after simulated coiling, which has a mean fluid domain > 1.0 cm/s. Result Follow-up angiograms showed 24 aneurysms in the stable group and 13 in the recurrence group. Mann-Whitney U test demonstrated that maximum size, dome volume, neck width, neck area, and coil packing density were significantly different between the two groups (P < 0.05). Among the hemodynamic parameters, aneurysms in the recurrence group had significantly larger inflow and outflow areas in the control CFD and larger RFVs in the porous media CFD. Multivariate logistic regression analyses demonstrated that RFV was the only independently significant factor (odds ratio, 1.06; 95% confidence interval, 1.01–1.11; P = 0.016). Conclusion The study findings suggest that RFV collected under porous media modeling predicts the recurrence of coiled aneurysms. PMID:29284057

Improvements in Technique of NMR Imaging and NMR Diffusion Measurements in the Presence of Background Gradients.

NASA Astrophysics Data System (ADS)

Lian, Jianyu

In this work, modification of the cosine current distribution rf coil, PCOS, has been introduced and tested. The coil produces a very homogeneous rf magnetic field, and it is inexpensive to build and easy to tune for multiple resonance frequency. The geometrical parameters of the coil are optimized to produce the most homogeneous rf field over a large volume. To avoid rf field distortion when the coil length is comparable to a quarter wavelength, a parallel PCOS coil is proposed and discussed. For testing rf coils and correcting B _1 in NMR experiments, a simple, rugged and accurate NMR rf field mapping technique has been developed. The method has been tested and used in 1D, 2D, 3D and in vivo rf mapping experiments. The method has been proven to be very useful in the design of rf coils. To preserve the linear relation between rf output applied on an rf coil and modulating input for an rf modulating -amplifying system of NMR imaging spectrometer, a quadrature feedback loop is employed in an rf modulator with two orthogonal rf channels to correct the amplitude and phase non-linearities caused by the rf components in the rf system. The modulator is very linear over a large range and it can generate an arbitrary rf shape. A diffusion imaging sequence has been developed for measuring and imaging diffusion in the presence of background gradients. Cross terms between the diffusion sensitizing gradients and background gradients or imaging gradients can complicate diffusion measurement and make the interpretation of NMR diffusion data ambiguous, but these have been eliminated in this method. Further, the background gradients has been measured and imaged. A dipole random distribution model has been established to study background magnetic fields Delta B and background magnetic gradients G_0 produced by small particles in a sample when it is in a B_0 field. From this model, the minimum distance that a spin can approach a particle can be determined by measuring and <{bf G}_sp{0 }{2}>. From this model, the particle concentration in a sample can be determined by measuring the lineshape of a free induction decay (fid).

In vivo operation of the Boston 15-channel wireless subretinal visual prosthesis

NASA Astrophysics Data System (ADS)

Shire, Douglas B.; Doyle, Patrick; Kelly, Shawn K.; Gingerich, Marcus D.; Chen, Jinghua; Cogan, Stuart F.; Drohan, William A.; Mendoza, Oscar; Theogarajan, Luke; Wyatt, John; Rizzo, Joseph F.

2010-02-01

This presentation concerns the engineering development of the Boston visual prosthesis for restoring useful vision to patients blind with degenerative retinal disease. A miniaturized, hermetically-encased, 15-channel wirelessly-operated retinal prosthetic was developed for implantation and pre-clinical studies in Yucatan mini-pig animal models. The prosthesis conforms to the eye and drives a microfabricated polyimide stimulating electrode array having sputtered iridium oxide electrodes. This array is implanted into the subretinal space using a specially-designed ab externo surgical technique; the bulk of the prosthesis is on the surface of the sclera. The implanted device includes a hermetic titanium case containing a 15-channel stimulator chip; secondary power/data receiving coils surround the cornea. Long-term in vitro pulse testing was also performed on the electrodes to ensure their stability over years of operation. Assemblies were first tested in vitro to verify wireless operation of the system in biological saline using a custom RF transmitter circuit and primary coils. Stimulation pulse strength, duration and frequency were programmed wirelessly using a computer with a custom graphical user interface. Operation of the retinal implant was verified in vivo in 3 minipigs for more than three months by measuring stimulus artifacts on the eye surface using contact lens electrodes.

A magnetic resonance (MR) microscopy system using a microfluidically cryo-cooled planar coil.

PubMed

Koo, Chiwan; Godley, Richard F; Park, Jaewon; McDougall, Mary P; Wright, Steven M; Han, Arum

2011-07-07

We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (-196 °C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: (1) the small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. (2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0 °C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system resulted in an average image SNR enhancement of 1.47 ± 0.11 times relative to similar room-temperature coils. This journal is © The Royal Society of Chemistry 2011

A Magnetic Resonance (MR) Microscopy System using a Microfluidically Cryo-Cooled Planar Coil

PubMed Central

Koo, Chiwan; Godley, Richard F.; Park, Jaewon; McDougall, Mary P.; Wright, Steven M.; Han, Arum

2011-01-01

We present the development of a microfluidically cryo-cooled planar coil for magnetic resonance (MR) microscopy. Cryogenically cooling radiofrequency (RF) coils for magnetic resonance imaging (MRI) can improve the signal to noise ratio (SNR) of the experiment. Conventional cryostats typically use a vacuum gap to keep samples to be imaged, especially biological samples, at or near room temperature during cryo-cooling. This limits how close a cryo-cooled coil can be placed to the sample. At the same time, a small coil-to-sample distance significantly improves the MR imaging capability due to the limited imaging depth of planar MR microcoils. These two conflicting requirements pose challenges to the use of cryo-cooling in MR microcoils. The use of a microfluidic based cryostat for localized cryo-cooling of MR microcoils is a step towards eliminating these constraints. The system presented here consists of planar receive-only coils with integrated cryo-cooling microfluidic channels underneath, and an imaging surface on top of the planar coils separated by a thin nitrogen gas gap. Polymer microfluidic channel structures fabricated through soft lithography processes were used to flow liquid nitrogen under the coils in order to cryo-cool the planar coils to liquid nitrogen temperature (−196°C). Two unique features of the cryo-cooling system minimize the distance between the coil and the sample: 1) The small dimension of the polymer microfluidic channel enables localized cooling of the planar coils, while minimizing thermal effects on the nearby imaging surface. 2) The imaging surface is separated from the cryo-cooled planar coil by a thin gap through which nitrogen gas flows to thermally insulate the imaging surface, keeping it above 0°C and preventing potential damage to biological samples. The localized cooling effect was validated by simulations, bench testing, and MR imaging experiments. Using this cryo-cooled planar coil system inside a 4.7 Tesla MR system resulted in an average image SNR enhancement of 1.47 ± 0.11 times relative to similar room-temperature coils. PMID:21603723

Performance of a 12-coil superconducting 'bumpy torus' magnet facility.

NASA Technical Reports Server (NTRS)

Roth, J. R.; Holmes, A. D.; Keller, T. A.; Krawczonek, W. M.

1972-01-01

The NASA-Lewis 'bumpy torus' facility consists of 12 superconducting coils, each 19 cm ID and capable of 3.0 tesla on their axes. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m, and are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Final shakedown tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The facility is now ready for use as a plasma physics research facility. A maximum magnetic field on the magnetic axis of 3.23 teslas has been held for a period of more than sixty minutes without a coil normalcy.

Quench Protection of SC Quadrupole Magnets

NASA Astrophysics Data System (ADS)

Feher, S.; Bossert, R.; Dimarco, J.; Mitchell, D.; Lamm, M. J.; Limon, P. J.; Mazur, P.; Nobrega, F.; Orris, D.; Ozelis, J. P.; Strait, J. B.; Tompkins, J. C.; Zlobin, A. V.; McInturff, A. D.

1997-05-01

The energy stored in a superconducting accelerator magnet is dissipated after a quench in the coil normal zones, heating the coil and generating a turn to turn and coil to ground voltage drop. Quench heaters are used to protect the superconducting magnet by greatly increasing the coil normal zone thus allowing the energy to be dissipated over a larger conductor volume. Such heaters will be required for the Fermilab/LBNL design of the high gradient quads (HGQ) designed for the LHC interaction regions. As a first step, heaters were installed and tested in several Tevatron low-β superconducting quadrupoles. Experimental studies in normal and superfluid helium are presented which show the heater-induced quench response as a function of magnet excitation current, magnet temperature and peak heater energy density.

Measured losses in superconductor magnets for 60-Hertz ac operation.

NASA Technical Reports Server (NTRS)

Hamlet, I. L.; Kilgore, R. A.

1971-01-01

Results of an experimental study of electrical losses in superconductor magnets. Preliminary 60-Hz ac loss data are presented for coils constructed of Nb3Sn ribbon, Nb-Ti cable, and multifilament Nb-Ti. Losses have been measured for different size coils up to approximately 20 cm in diameter. Of the conductor types tested, Nb3Sn ribbon has the lowest losses for ac operation. In Nb3Sn-ribbon coils of different sizes, the loss per unit length of conductor is shown to decrease with a decrease in the rate of change of current and to increase, in general, with increase in coil size. An important aspect of the study is the high degree of repeatability of the data.

Final Report on ITER Task Agreement 81-10

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

Brad J. Merrill

An International Thermonuclear Experimental Reactor (ITER) Implementing Task Agreement (ITA) on Magnet Safety was established between the ITER International Organization (IO) and the Idaho National Laboratory (INL) Fusion Safety Program (FSP) during calendar year 2004. The objectives of this ITA were to add new capabilities to the MAGARC code and to use this updated version of MAGARC to analyze unmitigated superconductor quench events for both poloidal field (PF) and toroidal field (TF) coils of the ITER design. This report documents the completion of the work scope for this ITA. Based on the results obtained for this ITA, an unmitigated quenchmore » event in an ITER larger PF coil does not appear to be as severe an accident as in an ITER TF coil.« less

Campaign for Levitation in LDX

NASA Astrophysics Data System (ADS)

Garnier, D. T.; Hansen, A. K.; Mauel, M. E.; Ortiz, E. E.; Boxer, A. C.; Ellsworth, J. L.; Karim, I.; Kesner, J.; Michael, P. C.; Zhukovsky, A.

2006-10-01

In the past year, preparations have been made for the first flight of the Levitated Dipole Experiment (LDX). LDX, which consists of a 560 kg superconducting coil floating within a 5 m diameter vacuum chamber, is designed to study fusion relevant plasmas confined in a dipole magnetic field. During the spring, a high temperature superconducting levitation coil was integrated into the LDX facility. Testing was undertaken to verify the thermal performance of the coil under expected levitation conditions. In addition, a real-time operating system digital control system was developed that will be used for the levitation control. In July, plasma experiments were conducted with all superconducting magnets in operation. While still supported, roughly 75% of the weight of the floating coil was magnetically lifted by the levitation coil above. A series of plasma experiments were conducted with the same magnetic geometry as will be the case during levitation. During August, the second generation launcher system will be installed. The launcher, which retracts beyond the plasma's last closed field lines during operation, is designed to safely catch the floating coil following an unexpected loss of control. After this installation, levitation experiments will commence.

Design of a 3T preamplifier which stability is insensitive to coil loading

NASA Astrophysics Data System (ADS)

Cao, Xueming; Fischer, Elmar; Korvink, Jan G.; Gruschke, Oliver; Hennig, Jürgen; Zaitsev, Maxim

2016-04-01

In MRI (magnetic resonance imaging), preamplifiers are needed to amplify signals obtained from MRI receiver coils. Under various loading conditions of the corresponding receiver coils, preamplifiers see different source impedance at their input and may become unstable. Therefore preamplifiers which stability is not sensitive to coil loading are desirable. In this article, a coil-loading-insensitive preamplifier for MRI is presented, derived from an unstable preamplifier. Different approaches to improve stability were used during this derivation. Since a very low noise factor is essential for MRI preamplifiers, noise contributions from passive components in the MRI preamplifier have to be considered during the stabilization process. As a result, the initially unstable preamplifier became stable with regard to coil loading, while other MRI requirements, as the extremely low noise factor, were still fulfilled. The newly designed preamplifier was manufactured, characterized and tested in the MRI spectrometer. Compared to a commercially available preamplifier, the newly designed preamplifier has similar imaging performance but other advantages like smaller size and better stability. Furthermore, presented stabilization approaches can be generalized to stabilize other unstable low-noise amplifiers.

New type of eddy current sensor for large-displacement test

NASA Astrophysics Data System (ADS)

Pan, Haifeng; Zhu, Huizhong; Fu, Zhibin; Xu, Yuzheng; Feng, Guanping

2001-09-01

In this paper a new type of large displacement eddy current sensor is developed to overcome the three main disadvantages of the traditional eddy current senor. For a traditional sensor, the measurement range is limited and less than one half of the diameter of the measuring coil. The output is high sensitivity to the changes of the target material and the cable length connected between the probe and the preamplifier. When the material or the cable length changed, it is necessary to readjust the preamplifier. The probe of the new eddy current sensor has three coaxial measuring coils, one is an exciting coil and the other two are receiving coils. The diameter of measuring coils is (Phi) 11 mm. The measurement range of this sensor is 40mm and almost four times of the diameter of the coil. The form of differential input and feedback amplification is used in signal amplifier. Thus the effect of the common modules, such as the changes of the target material and the cable length, can be counteracted well.

A size-adjustable radiofrequency coil for investigating plants in a Halbach magnet

NASA Astrophysics Data System (ADS)

Oligschläger, Dirk; Rehorn, Christian; Lehmkuhl, Sören; Adams, Michael; Adams, Alina; Blümich, Bernhard

2017-05-01

A radio-frequency coil with adjustable distance has been developed and tested for in-situ examination of growing plants. The Helmholtz-based coil design reduces laborious tuning and matching efforts encountered with solenoids wound around a growing stem or branch. Relaxation experiments were performed on tomato plants and winter wheat under controlled light irradiation. Changes in signal amplitude and in relaxation times T2 were recorded over day and night cycles. Peaks in distributions of relaxation times were attributed to different tissue components of two different plants.

MQXFS1 Quadrupole Fabrication Report

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

Ambrosio, G.; Anerella, M.; Bossert, R.

This report presents the fabrication and QC data of MQXFS1, the first short model of the low-beta quadrupoles (MQXF) for the LHC High Luminosity Upgrade. It describes the conductor, the coils, and the structure that make the MQXFS1 magnet. Qualification tests and non-conformities are also presented and discussed. The fabrication of MQXFS1 was started before the finalization of conductor and coil design for MQXF magnets. Two strand design were used (RRP 108/127 and RRP 132/169). Cable and coil cross-sections were “first generation”.

Design, analyses, fabrication and characterization of Nb3Sn coil in 1 W pulse tube cryocooler

NASA Astrophysics Data System (ADS)

Kundu, Ananya; Das, Subrat Kumar; Bano, Anees; Kumar, Nitish; Pradhan, Subrata

2017-02-01

A laboratory scale Nb3Sn coil is designed, analysed, fabricated and characterized in 1 W pulse tube cryocooler in solid nitrogen cooling mode and in conduction cooling mode. The magnetic field profile in axial and radial direction, Lorentz force component across the winding volume in operational condition are estimated in COMSOL. The coil is designed for 1.5 T at 100 A. It is fabricated in wind and react method. Before winding, the insulated Nb3Sn strand is wound on a copper mandrel which is thermally anchored with the 2nd stage of the cold head unit via a 10 mm thick copper ‘Z’ shaped plate The temperature distribution in 2nd cold stage, copper z plate and coil is monitored in both solid nitrogen cooling and conduction cooling mode. In solid nitrogen cooling mode, the quench of the coil occurs at 150 A for 0.01 A/s current ramp rate. The magnetic field at the centre of the coil bore is measured using transverse Hall sensor. The measured magnetic field value is compared with the analytical field value and they are found to be deviating ∼5% in magnitude. Again the coil is tested in conduction cooling mode maintaining the same current ramp rate and it is observed that the coil gets quenched at 70 A at temperature ∼ 10K.

A 31-channel MR brain array coil compatible with positron emission tomography.

PubMed

Sander, Christin Y; Keil, Boris; Chonde, Daniel B; Rosen, Bruce R; Catana, Ciprian; Wald, Lawrence L

2015-06-01

Simultaneous acquisition of MR and positron emission tomography (PET) images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (signal to noise ratio [SNR], g-factor) and PET attenuation. The coil design showed an improvement in attenuation by 190% (average) compared with conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical region of interest) compared with a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. © 2014 Wiley Periodicals, Inc.

Single bead detection with an NMR microcapillary probe.

PubMed

Nakashima, Yoshihiro; Boss, Michael; Russek, Stephen E; Moreland, John

2012-11-01

We have developed a nuclear magnetic resonance (NMR) microcapillary probe for the detection of single magnetic microbeads. The geometry of the probe has been optimized so that the signal from the background water has a similar magnitude compared to the signal from the dephased water nearby a single magnetic bead within the probe detector coil. In addition, the RF field of the coil must be uniform within the effective range of the magnetic bead. Three different RF probes were tested in a 7 T (300 MHz) pulsed NMR spectrometer with sample volumes ranging from 5 nL down to 1 nL. The 1 nL probe had a single-shot signal-to-noise ratio (SNR) for pure water of 27 and a volume resolution that exhibits a 600-fold improvement over a conventional (5 mm tube) NMR probe with a sample volume of 18 μL. This allowed for the detection of a 1 μm magnetite/polystyrene bead (m=2×10(-14)Am(2)) with an estimated experimental SNR of 30. Simulations of the NMR spectra for the different coil geometries and positions of the bead within the coil were developed that include the B(0) shift near a single bead, the inhomogeneity of the coils, the local coil sensitivity, the skin effect of the coil conductor, and quantitated estimates of the proximity effect between coil windings. Published by Elsevier Inc.

Effect of γ-Al2O3/water nanofluid on the thermal performance of shell and coil heat exchanger with different coil torsions

NASA Astrophysics Data System (ADS)

Elshazly, K. M.; Sakr, R. Y.; Ali, R. K.; Salem, M. R.

2017-06-01

This work investigated experimentally the thermal performance of shell and coil heat exchanger with different coil torsions (λ) for γ-Al2O3/water nanofluid flow. Five helically coiled tube (HCT) with 0.0442 ≤ λ ≤ 0.1348 were tested within turbulent flow regime. The average size of γ-Al2O3 particles is 40 nm and volume concentration (φ) is varied from 0 to 2%. Results showed that reducing coil torsion enhances the heat transfer rate and increases HCT-friction factor (fc). Also, it is noticed that HCT average Nusselt number (Nut) and fc of nanofluids increase with increasing γ-Al2O3 volume concentration. The thermal performance index, TPI = (ht,nf/ht,bf)/(ΔPc,nf/ΔPc,bf). increases with increasing nanoparticles concentration, coil torsion, HCT-side inlet temperature and nanofluid flow rate. Over the studied range of HCT-Reynolds number, the average value of TPI is of 1.34 and 2.24 at φ = 0.5% and φ = 2%, respectively. The average value of TPI is of 1.64 at λ = 0.0442 while its average value at λ = 0.1348 is of 2.01. One of the main contributions is to provide heat equipments designers with Nut and fc correlations for practical configurations shell and coil heat exchangers with a wide range of nanofluid concentration.

Initial Operation of the Nuclear Thermal Rocket Element Environmental Simulator

NASA Technical Reports Server (NTRS)

Emrich, William J., Jr.; Pearson, J. Boise; Schoenfeld, Michael P.

2015-01-01

The Nuclear Thermal Rocket Element Environmental Simulator (NTREES) facility is designed to perform realistic non-nuclear testing of nuclear thermal rocket (NTR) fuel elements and fuel materials. Although the NTREES facility cannot mimic the neutron and gamma environment of an operating NTR, it can simulate the thermal hydraulic environment within an NTR fuel element to provide critical information on material performance and compatibility. The NTREES facility has recently been upgraded such that the power capabilities of the facility have been increased significantly. At its present 1.2 MW power level, more prototypical fuel element temperatures nay now be reached. The new 1.2 MW induction heater consists of three physical units consisting of a transformer, rectifier, and inverter. This multiunit arrangement facilitated increasing the flexibility of the induction heater by more easily allowing variable frequency operation. Frequency ranges between 20 and 60 kHz can accommodated in the new induction heater allowing more representative power distributions to be generated within the test elements. The water cooling system was also upgraded to so as to be capable of removing 100% of the heat generated during testing In this new higher power configuration, NTREES will be capable of testing fuel elements and fuel materials at near-prototypic power densities. As checkout testing progressed and as higher power levels were achieved, several design deficiencies were discovered and fixed. Most of these design deficiencies were related to stray RF energy causing various components to encounter unexpected heating. Copper shielding around these components largely eliminated these problems. Other problems encountered involved unexpected movement in the coil due to electromagnetic forces and electrical arcing between the coil and a dummy test article. The coil movement and arcing which were encountered during the checkout testing effectively destroyed the induction coil in use at the time and resulted in NTREES being out of commission for a couple of months while a new stronger coil was procured. The new coil includes several additional pieces of support structure to prevent coil movement in the future. In addition, new insulating test article support components have been fabricated to prevent unexpected arcing to the test articles. Additional activities are also now underway to address ways in which the radial temperature profiles across test articles may be controlled such that they are more prototypical of what they would encounter in an operating nuclear engine. The causes of the temperature distribution problem are twofold. First, the fuel element test article is isolated in NTREES as opposed to being in the midst of many other mostly identical fuel elements in a nuclear engine. As a result, the fuel element heat flux boundary conditions in NTREES are far from adiabatic as would normally be the case in a reactor. Second, induction heating skews the power distribution such that power is preferentially deposited near the outside of the fuel element. Nuclear heating, conversely, deposits its power much more uniformly throughout the fuel element. Current studies are now looking at various schemes to adjust the amount of thermal radiation emitted from the fuel element surface so as to essentially vary the thermal boundary conditions on the test article. It is hoped that by properly adjusting the thermal boundary conditions on the fuel element test article, it may be possible to substantially correct for the inappropriate radial power distributions resulting from the induction heating so as to yield a more nearly correct temperature distribution throughout the fuel element.

Effect of thermo-mechanical stress during quench on Nb3Sn cable performance

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

Linda Imbasciati et al.

2002-12-09

Several high field magnets using Nb{sub 3}Sn superconductor are under development for future particle accelerators. The high levels of stored energy in these magnets can cause high peak temperatures during a quench. The thermomechanical stress generated in the winding during the fast temperature rise can result in a permanent damage of the brittle Nb{sub 3}Sn. Although there are several studies of the critical current degradation of Nb{sub 3}Sn strands due to strain, little is known about how to apply the strain limitations to define a maximum acceptable temperature in the coils during a quench. Therefore, an experimental program was launched,more » aimed at improving the understanding of the effect of thermo-mechanical stress in coils made from brittle Nb{sub 3}Sn. A first experiment, reported here, was performed on cables. The experimental results were compared to analytical and finite element models. The next step in the experimental program will be to repeat similar measurements in small racetrack coils and later in full size magnets.« less

An efficient calibration method for SQUID measurement system using three orthogonal Helmholtz coils

NASA Astrophysics Data System (ADS)

Hua, Li; Shu-Lin, Zhang; Chao-Xiang, Zhang; Xiang-Yan, Kong; Xiao-Ming, Xie

2016-06-01

For a practical superconducting quantum interference device (SQUID) based measurement system, the Tesla/volt coefficient must be accurately calibrated. In this paper, we propose a highly efficient method of calibrating a SQUID magnetometer system using three orthogonal Helmholtz coils. The Tesla/volt coefficient is regarded as the magnitude of a vector pointing to the normal direction of the pickup coil. By applying magnetic fields through a three-dimensional Helmholtz coil, the Tesla/volt coefficient can be directly calculated from magnetometer responses to the three orthogonally applied magnetic fields. Calibration with alternating current (AC) field is normally used for better signal-to-noise ratio in noisy urban environments and the results are compared with the direct current (DC) calibration to avoid possible effects due to eddy current. In our experiment, a calibration relative error of about 6.89 × 10-4 is obtained, and the error is mainly caused by the non-orthogonality of three axes of the Helmholtz coils. The method does not need precise alignment of the magnetometer inside the Helmholtz coil. It can be used for the multichannel magnetometer system calibration effectively and accurately. Project supported by the “Strategic Priority Research Program (B)” of the Chinese Academy of Sciences (Grant No. XDB04020200) and the Shanghai Municipal Science and Technology Commission Project, China (Grant No. 15DZ1940902).

Family-specific Kinesin Structures Reveal Neck-linker Length Based on Initiation of the Coiled-coil*

PubMed Central

Phillips, Rebecca K.; Peter, Logan G.; Gilbert, Susan P.

2016-01-01

Kinesin-1, -2, -5, and -7 generate processive hand-over-hand 8-nm steps to transport intracellular cargoes toward the microtubule plus end. This processive motility requires gating mechanisms to coordinate the mechanochemical cycles of the two motor heads to sustain the processive run. A key structural element believed to regulate the degree of processivity is the neck-linker, a short peptide of 12–18 residues, which connects the motor domain to its coiled-coil stalk. Although a shorter neck-linker has been correlated with longer run lengths, the structural data to support this hypothesis have been lacking. To test this hypothesis, seven kinesin structures were determined by x-ray crystallography. Each included the neck-linker motif, followed by helix α7 that constitutes the start of the coiled-coil stalk. In the majority of the structures, the neck-linker length differed from predictions because helix α7, which initiates the coiled-coil, started earlier in the sequence than predicted. A further examination of structures in the Protein Data Bank reveals that there is a great disparity between the predicted and observed starting residues. This suggests that an accurate prediction of the start of a coiled-coil is currently difficult to achieve. These results are significant because they now exclude simple comparisons between members of the kinesin superfamily and add a further layer of complexity when interpreting the results of mutagenesis or protein fusion. They also re-emphasize the need to consider factors beyond the kinesin neck-linker motif when attempting to understand how inter-head communication is tuned to achieve the degree of processivity required for cellular function. PMID:27462072

Experimental Demonstration and Circuitry for a Very Compact Coil-Only Pulse Echo EMAT

PubMed Central

Rueter, Dirk

2017-01-01

This experimental study demonstrates for the first time a solid-state circuitry and design for a simple compact copper coil (without an additional bulky permanent magnet or bulky electromagnet) as a contactless electromagnetic acoustic transducer (EMAT) for pulse echo operation at MHz frequencies. A pulsed ultrasound emission into a metallic test object is electromagnetically excited by an intense MHz burst at up to 500 A through the 0.15 mm filaments of the transducer. Immediately thereafter, a smoother and quasi “DC-like” current of 100 A is applied for about 1 ms and allows an echo detection. The ultrasonic pulse echo operation for a simple, compact, non-contacting copper coil is new. Application scenarios for compact transducer techniques include very narrow and hostile environments, in which, e.g., quickly moving metal parts must be tested with only one, non-contacting ultrasound shot. The small transducer coil can be operated remotely with a cable connection, separate from the much bulkier supply circuitry. Several options for more technical and fundamental progress are discussed. PMID:28441722

Design, simulation and testing of a novel radial multi-pole multi-layer magnetorheological brake

NASA Astrophysics Data System (ADS)

Wu, Jie; Li, Hua; Jiang, Xuezheng; Yao, Jin

2018-02-01

This paper deals with design, simulation and experimental testing of a novel radial multi-pole multi-layer magnetorheological (MR) brake. This MR brake has an innovative structural design with superposition principle of two magnetic fields generated by the inner coils and the outer coils. The MR brake has several media layers of magnetorheological (MR) fluid located between the inner coils and the outer coils, and it can provide higher torque and higher torque density than conventional single-disk or multi-disk or multi-pole single-layer MR brakes can. In this paper, a brief introduction to the structure of the proposed MR brake was given first. Then, theoretical analysis of the magnetic circuit and the braking torque was conducted. In addition, a 3D electromagnetic model of the MR brake was developed to simulate and examine the magnetic flux intensity and corresponding braking torque. A prototype of the brake was fabricated and several tests were carried out to validate its torque capacity. The results show that the proposed MR brake can produce a maximum braking torque of 133 N m and achieve a high torque density of 25.0 kN m-2, a high torque range of 42 and a high torque-to-power ratio of 0.95 N m W-1.

Developing Test Apparatus and Measurements of AC Loss of High Temperature Superconductors

DTIC Science & Technology

2012-11-01

temperature of the coil is not raised significantly. The second system, a larger machine, designed with a long term prospective to serve a test bed for...four sample chambers inside the vacuum gap, LN2 – cooled sample holder (currently only one is in use), the laminated back iron, and the outer shell...machine. accommodate a variety of different small coils and linear tapes. This assembly is surrounded by the laminated back iron and the outer shell

Radial magnetic resonance imaging (MRI) using a rotating radiofrequency (RF) coil at 9.4 T.

PubMed

Li, Mingyan; Weber, Ewald; Jin, Jin; Hugger, Thimo; Tesiram, Yasvir; Ullmann, Peter; Stark, Simon; Fuentes, Miguel; Junge, Sven; Liu, Feng; Crozier, Stuart

2018-02-01

The rotating radiofrequency coil (RRFC) has been developed recently as an alternative approach to multi-channel phased-array coils. The single-element RRFC avoids inter-channel coupling and allows a larger coil element with better B 1 field penetration when compared with an array counterpart. However, dedicated image reconstruction algorithms require accurate estimation of temporally varying coil sensitivities to remove artefacts caused by coil rotation. Various methods have been developed to estimate unknown sensitivity profiles from a few experimentally measured sensitivity maps, but these methods become problematic when the RRFC is used as a transceiver coil. In this work, a novel and practical radial encoding method is introduced for the RRFC to facilitate image reconstruction without the measurement or estimation of rotation-dependent sensitivity profiles. Theoretical analyses suggest that the rotation-dependent sensitivities of the RRFC can be used to create a uniform profile with careful choice of sampling positions and imaging parameters. To test this new imaging method, dedicated electronics were designed and built to control the RRFC speed and hence positions in synchrony with imaging parameters. High-quality phantom and animal images acquired on a 9.4 T pre-clinical scanner demonstrate the feasibility and potential of this new RRFC method. Copyright © 2017 John Wiley & Sons, Ltd.

Retreatment of recanalized aneurysms after Y-stent-assisted coil embolization with double enterprise stents: case report and systematic review of the literature.

PubMed

Kono, Kenichi; Shintani, Aki; Terada, Tomoaki

2014-01-01

It is necessary to consider possibility of recanalization and retreatment after coil embolization for cerebral aneurysms. There is concern that retreatment for recanalized aneurysms after Y-stent-assisted coil embolization may be difficult because of double stents, especially in Y-stents with double closed-cell stents owing to narrowed structures. However, no detailed reports of retreatment after Y-stent have been reported. Between July 2010 and June 2013, we treated four aneurysms with Y-stent-assisted coil embolization using Enterprise closed-cell stents. Recanalization occurred in one case (25%), and retreatment was performed. We easily navigated a microcatheter into the target portions of the aneurysm through the Y-stent and occluded the aneurysm with coils. Additionally, by systematically searching in PubMed, we found 105 cases of Y-stent-assisted coil embolization using Enterprise stents or Neuroform stents with more than 6 months of follow-up. Among them, retreatment was performed in 10 cases (9.5%). There were no significant differences in retreatment rates among different stent combinations (P=0.91; Fisher's exact test). In conclusion, navigation of a microcatheter into the aneurysm through the Y-stent with double Enterprise stents was feasible, and retreatment rates after Y-stent-assisted coiling may not depend on stent combinations.

An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers.

PubMed

Li, Zhen-hua; Li, Hong-bin; Zhang, Zhi

2013-07-01

Electronic transformers are widely used in power systems because of their wide bandwidth and good transient performance. However, as an emerging technology, the failure rate of electronic transformers is higher than that of traditional transformers. As a result, the calibration period needs to be shortened. Traditional calibration methods require the power of transmission line be cut off, which results in complicated operation and power off loss. This paper proposes an online calibration system which can calibrate electronic current transformers without power off. In this work, the high accuracy standard current transformer and online operation method are the key techniques. Based on the clamp-shape iron-core coil and clamp-shape air-core coil, a combined clamp-shape coil is designed as the standard current transformer. By analyzing the output characteristics of the two coils, the combined clamp-shape coil can achieve verification of the accuracy. So the accuracy of the online calibration system can be guaranteed. Moreover, by employing the earth potential working method and using two insulating rods to connect the combined clamp-shape coil to the high voltage bus, the operation becomes simple and safe. Tests in China National Center for High Voltage Measurement and field experiments show that the proposed system has a high accuracy of up to 0.05 class.

Missense mutation in DISC1 C-terminal coiled-coil has GSK3β signaling and sex-dependent behavioral effects in mice

PubMed Central

Dachtler, James; Elliott, Christina; Rodgers, R. John; Baillie, George S.; Clapcote, Steven J.

2016-01-01

Disrupted-in-Schizophrenia 1 (DISC1) is a risk factor for schizophrenia and affective disorders. The full-length DISC1 protein consists of an N-terminal ‘head’ domain and a C-terminal tail domain that contains several predicted coiled-coils, structural motifs involved in protein-protein interactions. To probe the in vivo effects of missense mutation of DISC1’s C-terminal tail, we tested mice carrying mutation D453G within a predicted α-helical coiled-coil region. We report that, relative to wild-type littermates, female DISC1D453G mice exhibited novelty-induced hyperlocomotion, an anxiogenic profile in the elevated plus-maze and open field tests, and reduced social exploration of unfamiliar mice. Male DISC1D453G mice displayed a deficit in passive avoidance, while neither males nor females exhibited any impairment in startle reactivity or prepulse inhibition. Whole brain homogenates showed normal levels of DISC1 protein, but decreased binding of DISC1 to GSK3β, decreased phospho-inhibition of GSK3β at serine 9, and decreased levels of β-catenin in DISC1D453G mice of either sex. Interrupted GSK3β signaling may thus be part of the mechanism underlying the behavioral phenotype associated with D453G, in common with the previously described N-terminal domain mutations Q31L and L100P in mice, and the schizophrenia risk-conferring variant R264Q in humans. PMID:26728762

3D model of a matrix source of negative ions: RF driving by a large area planar coil

NASA Astrophysics Data System (ADS)

Demerdzhiev, A.; Lishev, St.; Tarnev, Kh.; Shivarova, A.

2015-04-01

Based on three-dimensional (3D) modeling, different manners of a planar-coil inductive discharge driving of a plasma source completed as a matrix of small-radius hydrogen discharges are studied regarding a proper choice of an efficient and alike rf power deposition into the separate discharges of the matrix. Driving the whole matrix by a single coil and splitting it to blocks of discharge tubes, with single coil driving of each block, are the two cases considered. The results from the self-consistent model presented for a block of discharge tubes show its reliability in ensuring the same spatial distribution of the plasma parameters in the discharges completing the block. Since regarding the construction of the matrix, its driving as a whole by a single coil is the most reasonable decision, three modifications of the coil design have been tested: two zigzag coils with straight conductors passing, respectively, between and through the bottoms of the discharge tubes and a coil with an "omega" shaped conductor on the bottom of each tube. Among these three configurations, the latter ‒ a coil with an Ω-shaped conductor on the bottom of each tube ‒ shows up with the highest rf efficiency of an inductive discharge driving, shown by results for the rf current induced in the discharges obtained from an electrodynamical description. In all the cases considered the spatial distribution of the induced current density is analysed based on the manner of the penetration into the plasma of the wave field sustaining the inductive discharges.

Experimental approach to investigate the constrained recovery behavior of coiled monofilament polymer fibers

NASA Astrophysics Data System (ADS)

Mendes, S. S.; Nunes, L. C. S.

2017-11-01

The aim of this work is to propose a new approach for investigating the thermo-mechanical behavior of coiled oriented polymer fibers with fixed ends and promote an understanding of the actuation response of coiled polymers in constrained recovery applications. In the proposed experimental methodology, a coiled fiber was pre-stretched by 50% and the distance between its ends remained constant, then it was subjected to a heating-cooling cycle ranging from 30 °C to 120 °C and the induced restoring force was measured. Based on these measurements, axial deformation and shear strain were obtained from full-field displacements extracted by the digital image correlation method from images of the coiled fiber. Three coiled fibers with different initial pitch angles were manufactured, and samples with lengths of 15 mm and 20 mm were tested. Bias angles and coil radius were also estimated using the experimental data associated with the helical spring theory. Results show that significant shape changes can be noticed above the glass transition temperature (47 °C), and these changes induce variation in the resultant forces. The effects of thermal softening and thermal contraction for a modest negative thermal expansion coefficient became evident at temperatures ranging from ∼47 °C to ∼90 °C, while the response of a coiled homochiral polymer fiber was achieved at temperatures close to 90 °C. During the cooling process, saturated states of the axial deformation and shear strain of the coiled fibers were observed at temperatures between 120 °C and 100 °C.

All-fiber linearly polarized laser oscillator by fiber coiling loss control

NASA Astrophysics Data System (ADS)

Huang, Yu-Sheng; Xiao, Qi-Rong; Li, Dan; Wang, Ze-Hui; Wang, Xue-Jiao; Yan, Ping; Gong, Ma-Li

2018-04-01

Not Available Project supported by the National Key Research and Development Program of China (Grant No. 2017YFB1104500), the National Natural Science Foundation of China (Grant No. 61675114), and theTsinghua University (THU) Initiative Scientific Research Program, China (Grant No. 20151080709).

Development of a Tunnel Diode Resonator technique for magnetic measurements in Electrostatic Levitation chamber

NASA Astrophysics Data System (ADS)

Spyrison, N. S.; Prommapan, P.; Kim, H.; Maloney, J.; Rustan, G. E.; Kreyssig, A.; Goldman, A. I.; Prozorov, R.

2011-03-01

The incorporation of the Tunnel Diode Resonator (TDR) technique into an ElectroStatic Levitation (ESL) apparatus was explored. The TDR technique is known to operate and behave well at low temperatures with careful attention to coil-sample positioning in a dark, shielded environment. With these specifications a frequency resolution of 10-9 in a few seconds counting time can be achieved. Complications arise when this technique is applied in the ESL chamber where a sample of molten metal is levitating less then 10 mm from the coil in a large electrostatic field. We have tested a variety of coils unconventional to TDR; including Helmholtz pairs and Archimedean spiral coils. Work was supported by the Nation Science Foundation under grant DMR-08-17157

Lessons learned from the manufacture of the W7-X planar coils

NASA Astrophysics Data System (ADS)

Viebke, H.; Gustke, D.; Rummel, T.; Sborchia, C.; Schroeder, R.; Williams, D.; Bates, S.; Leigh, B.; Winter, R.

2006-06-01

WENDELSTEIN 7-X (W7-X) is a superconducting stellarator. The planar coils are in charge to modify the magnetic filed configuration of the W7-X. The major challenges during manufacturing were the fabrication of the cable-in-conduit conductor, the accuracy of the coil cases after welding and machining and the development of electrical joints with a resistance below 1 nΩ. Leaks were detected during repetitive in the case cooling system, which were caused by stress corrosion cracking. High voltage tests in a reduced vacuum environment (Paschen conditions) revealed that the insulation had to be reinforced and the quench detection wires had to be exchanged. This paper gives an overview about the main technical challenges of the planar coils and the lessons learned during production.

Intermediate filament mechanics in vitro and in the cell: from coiled coils to filaments, fibers and networks.

PubMed

Köster, Sarah; Weitz, David A; Goldman, Robert D; Aebi, Ueli; Herrmann, Harald

2015-02-01

Intermediate filament proteins form filaments, fibers and networks both in the cytoplasm and the nucleus of metazoan cells. Their general structural building plan accommodates highly varying amino acid sequences to yield extended dimeric α-helical coiled coils of highly conserved design. These 'rod' particles are the basic building blocks of intrinsically flexible, filamentous structures that are able to resist high mechanical stresses, that is, bending and stretching to a considerable degree, both in vitro and in the cell. Biophysical and computer modeling studies are beginning to unfold detailed structural and mechanical insights into these major supramolecular assemblies of cell architecture, not only in the 'test tube' but also in the cellular and tissue context. Copyright © 2015 Elsevier Ltd. All rights reserved.

Auto-tuning system for NMR probe with LabView

NASA Astrophysics Data System (ADS)

Quen, Carmen; Mateo, Olivia; Bernal, Oscar

2013-03-01

Typical manual NMR-tuning method is not suitable for broadband spectra spanning several megahertz linewidths. Among the main problems encountered during manual tuning are pulse-power reproducibility, baselines, and transmission line reflections, to name a few. We present a design of an auto-tuning system using graphic programming language, LabVIEW, to minimize these problems. The program is designed to analyze the detected power signal of an antenna near the NMR probe and use this analysis to automatically tune the sample coil to match the impedance of the spectrometer (50 Ω). The tuning capacitors of the probe are controlled by a stepper motor through a LabVIEW/computer interface. Our program calculates the area of the power signal as an indicator to control the motor so disconnecting the coil to tune it through a network analyzer is unnecessary. Work supported by NSF-DMR 1105380

Status of MSBS Study at NAL in 1995

NASA Technical Reports Server (NTRS)

Sawada, Hideo; Suenaga, Hisasi; Kunimasu, Tetuya; Kohno, Takashi

1996-01-01

Magnetic field intensity and currents passing through the coils of the National Aerospace Laboratory (NAL) 1O cm Magnetic Suspension and Balance System (MSBS) were measured while a cylindrical model was oscillated along x,y,z and also about y and z axes, respectively. The model was made of alnico 5 and was 8 mm in diameter and 60 mm long. Two kinds of tests were carried out. Amplitude of the oscillation was varied at a frequency of 10 Hz. Frequency was varied from 1 to 50 Hz in the other test. Results of the tests show that the relation between coil currents and magnetic force acting on the model is affected by frequency. They also show that the relation between measured magnetic field intensity and the force in vertical direction is independent of the frequency below 30 Hz. Using the measured magnetic field intensity, the vertical force can be evaluated at the MSBS instantaneously when a model moves at frequencies below 30 Hz. A static drag force calibration test was carried out at the 60 cm MSBS. Obtained relationships between measured drag coil currents and loads shows large hysteresis.

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

Yu, M.; Lombardo, V.; Turrioni, D.

Helical solenoids that provide solenoid, helical dipole and helical gradient field components are designed for a helical cooling channel (HCC) proposed for cooling of muon beams in a muon collider. The high temperature superconductor (HTS), 12 mm wide and 0.1 mm thick YBCO tape, is used as the conductor for the highest-field section of HCC due to certain advantages, such as its electrical and mechanical properties. To study and address the design, and technological and performance issues related to magnets based on YBCO tapes, a short helical solenoid model based on double-pancake coils was designed, fabricated and tested at Fermilab.more » Splicing joints were made with Sn-Pb solder as the power leads and the connection between coils, which is the most critical element in the magnet that can limit the performance significantly. This paper summarizes the test results of YBCO tape and double-pancake coils in liquid nitrogen and liquid helium, and then focuses on the study of YBCO splices, including the soldering temperatures and pressures, and splice bending test.« less

Evaluation of an image-based tracking workflow using a passive marker and resonant micro-coil fiducials for automatic image plane alignment in interventional MRI.

PubMed

Neumann, M; Breton, E; Cuvillon, L; Pan, L; Lorenz, C H; de Mathelin, M

2012-01-01

In this paper, an original workflow is presented for MR image plane alignment based on tracking in real-time MR images. A test device consisting of two resonant micro-coils and a passive marker is proposed for detection using image-based algorithms. Micro-coils allow for automated initialization of the object detection in dedicated low flip angle projection images; then the passive marker is tracked in clinical real-time MR images, with alternation between two oblique orthogonal image planes along the test device axis; in case the passive marker is lost in real-time images, the workflow is reinitialized. The proposed workflow was designed to minimize dedicated acquisition time to a single dedicated acquisition in the ideal case (no reinitialization required). First experiments have shown promising results for test-device tracking precision, with a mean position error of 0.79 mm and a mean orientation error of 0.24°.

Unsteady heat dissipation in accelerator superconducting coils insulated with porous ceramic insulation in normal and supercritical helium conditions

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

Pietrowicz, S.; Four, A.; Baudouy, B.

To investigate the unsteady heat dissipation in accelerator superconducting coils insulated with porous ceramic insulation, two experimental mock-ups reproducing the thermal and the mechanical conditions of a superconducting coils were produced. The mock-ups with compressive load of 10 MPa and 20 MPa were tested at normal (T = 4.23 K and p = 1 bar) and supercritical helium conditions (T = 4.23 K and p = 2.0 to 3.75 bar) during unsteady heat dissipation. The paper presents the experimental results of temperature rise in both superconducting coils as a function of time for a wide range of a localized heatmore » load varying from 0.1 kJ/m{sup 3} up to 12.8 MJ m{sup −3} per pulse. A numerical model of the transient process in these coils has been developed and the computations are compared with the experimental results.« less

Thin film eddy current impulse deicer

NASA Technical Reports Server (NTRS)

Smith, Samuel O.; Zieve, Peter B.

1990-01-01

Two new styles of electrical impulse deicers has been developed and tested in NASA's Icing Research Tunnel. With the Eddy Current Repulsion Deicing Boot (EDB), a thin and flexible spiral coil is encapsulated between two thicknesses of elastomer. The coil, made by an industrial printed circuit board manufacturer, is bonded to the aluminum aircraft leading edge. A capacitor bank is discharged through the coil. Induced eddy currents repel the coil from the aluminum aircraft structure and shed accumulated ice. A second configuration, the Eddy Current Repulsion Deicing-Strip (EDS) uses an outer metal erosion strip fastened over the coil. Opposite flowing eddy currents repel the strip and create the impulse deicing force. The outer strip serves as a surface for the collection and shedding of ice and does not require any structural properties. The EDS is suitable for composite aircraft structures. Both systems successfully dispelled over 95 percent of the accumulated ice from airfoils over the range of the FAA icing envelope.

A persistent-mode 0.5 T solid-nitrogen-cooled MgB2 magnet for MRI.

PubMed

Ling, Jiayin; Voccio, John P; Hahn, Seungyong; Qu, Timing; Bascuñán, Juan; Iwasa, Yukikazu

2017-02-01

This paper presents construction details and test results of a persistent-mode 0.5-T MgB 2 magnet developed at the Francis Bitter Magnet Lab, MIT. The magnet, of 276-mm inner diameter and 290-mm outer diameter, consisted of a stack of 8 solenoidal coils with a total height of 460 mm. Each coil was wound with monofilament MgB 2 wire, equipped with a persistent-current switch and terminated with a superconducting joint, forming an individual superconducting loop. Resistive solder joints connected the 8 coils in series. The magnet, after being integrated into a testing system, immersed in solid nitrogen, was operated in a temperature range of 10-13 K. A two-stage cryocooler was deployed to cool a radiation shield and the cold mass that included mainly ~60 kg of solid nitrogen and the magnet. The solid nitrogen was capable of providing a uniform and stable cryogenic environment to the magnet. The magnet sustained a 0.47-T magnetic field at its center persistently in a range of 10-13 K. The current in each coil was inversely calculated from the measured field profile to determine the performance of each coil in persistent-mode operation. Persistent-current switches were successfully operated in solid nitrogen for ramping the magnet. They were also designed to absorb magnetic energy in a protection mechanism; its effectiveness was evaluated in an induced quench.

Carotid and vertebral artery sacrifice with a combination of Onyx and coils: technical note and case series.

PubMed

Chalouhi, Nohra; Starke, Robert M; Tjoumakaris, Stavropoula I; Jabbour, Pascal M; Gonzalez, L Fernando; Hasan, David; Rosenwasser, Robert H; Dumont, Aaron S

2013-08-01

Permanent vessel sacrifice has become a routine for the management of aneurysms, pseudoaneurysms, tumors, and carotid blowouts. The purpose of this study is to describe a new technique for carotid and vertebral artery sacrifice using a combination of Onyx and coils and to assess its feasibility, safety, and efficacy. The technique consists of deploying a few coils in the parent vessel under proximal flow arrest followed by Onyx embolization directly into the coil mass. A total of 41 patients underwent carotid/vertebral artery sacrifice using this technique in our institution. A total of 26 internal carotid arteries and 15 vertebral arteries were treated. In all but one patient, a balloon test occlusion was performed prior to permanent arterial sacrifice. The mean number of coils used was 6.8 (range, 2-19). The total volume of Onyx used was 1.3 ml on average (range, 0.2-5.2 ml). All 41 (100%) parent arteries were successfully occluded. No distal migration of Onyx or coils was noted. Periprocedural complications occurred in 14.6% (6/41) of cases causing permanent morbidity in 7.3% (3/41). No patient developed a recurrence during the follow-up period (mean, 14 months). Parent vessel sacrifice with a combination of Onyx and coils appears to be feasible, safe, and effective and may be an alternative to the traditional deconstruction technique with coils alone. The risk of thromboembolism exists with this technique, but there were no instances of Onyx migration.

Boehringer Mannheim award lecture 1995. La conference Boehringer Mannheim 1995. De novo design of alpha-helical proteins: basic research to medical applications.

PubMed

Hodges, R S

1996-01-01

The two-stranded alpha-helical coiled-coil is a universal dimerization domain used by nature in a diverse group of proteins. The simplicity of the coiled-coil structure makes it an ideal model system to use in understanding the fundamentals of protein folding and stability and in testing the principles of de novo design. The issues that must be addressed in the de novo design of coiled-coils for use in research and medical applications are (i) controlling parallel versus antiparallel orientation of the polypeptide chains, (ii) controlling the number of helical strands in the assembly (iii) maximizing stability of homodimers or heterodimers in the shortest possible chain length that may require the engineering of covalent constraints, and (iv) the ability to have selective heterodimerization without homodimerization, which requires a balancing of selectivity versus affinity of the dimerization strands. Examples of our initial inroads in using this de novo design motif in various applications include: heterodimer technology for the detection and purification of recombinant peptides and proteins; a universal dimerization domain for biosensors; a two-stage targeting and delivery system; and coiled-coils as templates for combinatorial helical libraries for basic research and drug discovery and as synthetic carrier molecules. The universality of this dimerization motif in nature suggests an endless number of possibilities for its use in de novo design, limited only by the creativity of peptide-protein engineers.

The manufacturing, assembly and acceptance testing of the breadboard cryogenic Optical Delay Line for DARWIN

NASA Astrophysics Data System (ADS)

van den Dool, T. C.; Kamphues, F.; Gielesen, W.; Dorrepaal, M.; Doelman, N.; Loix, N.; Verschueren, J. P.; Kooijman, P. P.; Visser, M.; Velsink, G.; Fleury, K.

2005-08-01

TNO, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has developed a compact breadboard cryogenic Optical Delay Line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard delay line is representative of a future flight mechanism, with all used materials and processes being flight representative. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a two-mirror cat's eye. Magnetic bearings are used for guiding. They provide frictionless and wear free operation with zero-hysteresis. The manufacturing, assembly and acceptance testing have been completed and are reported in this paper. The verification program, including functional testing at 40 K, will start in the final quarter of 2005.

Quench Protection Studies of 11T Nb$$_3$$Sn Dipole Models for LHC Upgrades

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

Zlobin, Alexander; Chlachidze, Guram; Nobrega, Alfred

CERN and FNAL are developing 11 T Nb3Sn dipole magnets for the LHC collimation system upgrade. Due to the large stored energy, protection of these magnets during a quench is a challenging problem. This paper reports the results of experimental studies of key quench protection parameters including longitudinal and radial quench propagation in the coil, coil heating due to a quench, and energy extraction and quench-back effect. The studies were performed using a 1 m long 11 T Nb3Sn dipole coil tested in a magnetic mirror configuration.

1 MVA HTS-2G Generator for Wind Turbines

NASA Astrophysics Data System (ADS)

Kovalev, K. L.; Poltavets, V. N.; Ilyasov, R. I.; Verzhbitsky, L. G.; Kozub, S. S.

2017-10-01

The calculation, design simulations and design performance of 1 MVA HTS-2G (second-generation high-temperature superconductor) Generator for Wind Turbines were done in 2013-2014 [1]. The results of manufacturing and testing of 1 MVA generator are presented in the article. HTS-2G field coils for the rotor were redesigned, fabricated and tested. The tests have shown critical current of the coils, 41-45 A (self field within the ferromagnetic core, T = 77 K), which corresponds to the current of short samples at self field. Application of the copper inner frame on the pole has improved internal cooling conditions of HTS coil windings and reduced the magnetic field in the area, thereby increased the critical current value. The original construction of the rotor with a rotating cryostat was developed, which decreases the thermal in-flow to the rotor. The stator of 1 MW HTS-2G generator has been manufactured. In order to improve the specific weight of the generator, the wave (harmonic drive) multiplier was used, which provides increasing RPM from 15 RPM up to 600 RPM. The total mass of the multiplier and generator is significantly smaller compared to traditional direct-drive wind turbines generators [2-7]. Parameters of the multiplier and generator were chosen based on the actual parameters of wind turbines, namely: 15 RPM, power is 1 MVA. The final test of the assembled synchronous generator with HTS-2G field coils for Wind Turbines with output power 1 MVA was completed during 2015.

Operational experience with the supercritical helium during the TF coils tests campaign of SST-1

NASA Astrophysics Data System (ADS)

Panchal, Rohitkumar Natvarlal; Patel, Rakesh; Tank, Jignesh; Mahesuria, Gaurang; Sonara, Dashrath; Tanna, Vipul; Patel, Jayant; Srikanth, G. L. N.; Singh, Manoj; Patel, Ketan; Christian, Dikens; Garg, Atul; Bairagi, Nitn; Gupta, Manoj Kumar; Nimavat, Hiren; Shah, Pankil; Sharma, Rajiv; Pradhan, Subrata

2012-06-01

Under the 'SST-1 mission mandate' recently, all the sixteen Steady State Superconducting Tokamak (SST-1) Toroidal Field (TF) magnets have been successfully tested at their nominal currents of 10000 A in cold under supercritical helium (SHe) flow conditions. The TF magnets test campaign have begun in an experimental cryostat since June 2010 with the SST-1 Helium cryogenics facility, which is a 1.3 kW at 4.5 K helium refrigerator-cum-liquefier (HRL) system. The HRL provides ~300 g-s-1supercritical helium (SHe) with cold circulator (CC) as well as ~ 60 g-s-1 without cold circulator to fulfill the forced flow cooling requirements of SST- 1 magnets. In case of single TF coil tests, we can adjust HRL process parameters such that an adequate amount of required supercritical helium is available without the cold circulator. In this paper, the complete process is describing the Process Flow Diagram (PFD) of 1.3 kW at 4.5 K HRL, techniques to generate supercritical helium without using the cold-circulator and the results of the cooldown, steady state characteristics and experience of supercritical helium operations during the TF coils test campaign have been discussed.

Dual optimization method of radiofrequency and quasistatic field simulations for reduction of eddy currents generated on 7T radiofrequency coil shielding.

PubMed

Zhao, Yujuan; Zhao, Tiejun; Raval, Shailesh B; Krishnamurthy, Narayanan; Zheng, Hai; Harris, Chad T; Handler, William B; Chronik, Blaine A; Ibrahim, Tamer S

2015-11-01

To optimize the design of radiofrequency (RF) shielding of transmit coils at 7T and reduce eddy currents generated on the RF shielding when imaging with rapid gradient waveforms. One set of a four-element, 2 × 2 Tic-Tac-Toe head coil structure was selected and constructed to study eddy currents on the RF coil shielding. The generated eddy currents were quantitatively studied in the time and frequency domains. The RF characteristics were studied using the finite difference time domain method. Five different kinds of RF shielding were tested on a 7T MRI scanner with phantoms and in vivo human subjects. The eddy current simulation method was verified by the measurement results. Eddy currents induced by solid/intact and simple-structured slotted RF shielding significantly distorted the gradient fields. Echo-planar images, B1+ maps, and S matrix measurements verified that the proposed slot pattern suppressed the eddy currents while maintaining the RF characteristics of the transmit coil. The presented dual-optimization method could be used to design RF shielding and reduce the gradient field-induced eddy currents while maintaining the RF characteristics of the transmit coil. © 2014 Wiley Periodicals, Inc.

Multiple-animal MR imaging using a 3T clinical scanner and multi-channel coil for volumetric analysis in a mouse tumor model.

PubMed

Mitsuda, Minoru; Yamaguchi, Masayuki; Furuta, Toshihiro; Nabetani, Akira; Hirayama, Akira; Nozaki, Atsushi; Niitsu, Mamoru; Fujii, Hirofumi

2011-01-01

Multiple small-animal magnetic resonance (MR) imaging to measure tumor volume may increase the throughput of preclinical cancer research assessing tumor response to novel therapies. We used a clinical scanner and multi-channel coil to evaluate the usefulness of this imaging to assess experimental tumor volume in mice. We performed a phantom study to assess 2-dimensional (2D) geometric distortion using 9-cm spherical and 32-cell (8×4 one-cm(2) grids) phantoms using a 3-tesla clinical MR scanner and dedicated multi-channel coil composed of 16 5-cm circular coils. Employing the multi-channel coil, we simultaneously scanned 6 or 8 mice bearing sarcoma 180 tumors. We estimated tumor volume from the sum of the product of tumor area and slice thickness on 2D spin-echo images (repetition time/echo time, 3500/16 ms; in-plane resolution, 0.195×0.195×1 mm(3)). After MR acquisition, we excised and weighed tumors, calculated reference tumor volumes from actual tumor weight assuming a density of 1.05 g/cm(3), and assessed the correlation between the estimated and reference volumes using Pearson's test. Two-dimensional geometric distortion was acceptable below 5% in the 9-cm spherical phantom and in every cell in the 32-cell phantom. We scanned up to 8 mice simultaneously using the multi-channel coil and found 11 tumors larger than 0.1 g in 12 mice. Tumor volumes were 1.04±0.73 estimated by MR imaging and 1.04±0.80 cm(3) by reference volume (average±standard deviation) and highly correlated (correlation coefficient, 0.995; P<0.01, Pearson's test). Use of multiple small-animal MR imaging employing a clinical scanner and multi-channel coil enabled accurate assessment of experimental tumor volume in a large number of mice and may facilitate high throughput monitoring of tumor response to therapy in preclinical research.

The significant impact of framing coils on long-term outcomes in endovascular coiling for intracranial aneurysms: how to select an appropriate framing coil.

PubMed

Ishida, Wataru; Sato, Masayuki; Amano, Tatsuo; Matsumaru, Yuji

2016-09-01

OBJECTIVE The importance of a framing coil (FC)-the first coil inserted into an aneurysm during endovascular coiling, also called a lead coil or a first coil-is recognized, but its impact on long-term outcomes, including recanalization and retreatment, is not well established. The purposes of this study were to test the hypothesis that the FC is a significant factor for aneurysmal recurrence and to provide some insights on appropriate FC selection. METHODS The authors retrospectively reviewed endovascular coiling for 280 unruptured intracranial aneurysms and gathered data on age, sex, aneurysm location, aneurysm morphology, maximal size, neck width, adjunctive techniques, recanalization, retreatment, follow-up periods, total volume packing density (VPD), volume packing density of the FC, and framing coil percentage (FCP; the percentage of FC volume in total coil volume) to clarify the associated factors for aneurysmal recurrence. RESULTS Of 236 aneurysms included in this study, 33 (14.0%) had recanalization, and 18 (7.6%) needed retreatment during a mean follow-up period of 37.7 ± 16.1 months. In multivariate analysis, aneurysm size (odds ratio [OR] = 1.29, p < 0.001), FCP < 32% (OR 3.54, p = 0.009), and VPD < 25% (OR 2.96, p = 0.015) were significantly associated with recanalization, while aneurysm size (OR 1.25, p < 0.001) and FCP < 32% (OR 6.91, p = 0.017) were significant predictors of retreatment. VPD as a continuous value or VPD with any cutoff value could not predict retreatment with statistical significance in multivariate analysis. CONCLUSIONS FCP, which is equal to the FC volume as a percentage of the total coil volume and is unaffected by the morphology of the aneurysm or the measurement error in aneurysm length, width, or height, is a novel predictor of recanalization and retreatment and is more significantly predictive of retreatment than VPD. To select FCs large enough to meet the condition of FCP ≥ 32% is a potential relevant factor for better long-term outcomes. These findings support our hypothesis that the FC is a significant factor for aneurysmal recurrence.

A High-Performance Portable Transient Electro-Magnetic Sensor for Unexploded Ordnance Detection.

PubMed

Wang, Haofeng; Chen, Shudong; Zhang, Shuang; Yuan, Zhiwen; Zhang, Haiyang; Fang, Dong; Zhu, Jun

2017-11-17

Portable transient electromagnetic (TEM) systems can be well adapted to various terrains, including mountainous, woodland, and other complex terrains. They are widely used for the detection of unexploded ordnance (UXO). As the core component of the portable TEM system, the sensor is constructed with a transmitting coil and a receiving coil. Based on the primary field of the transmitting coil and internal noise of the receiving coil, the design and testing of such a sensor is described in detail. Results indicate that the primary field of the transmitting coil depends on the diameter, mass, and power of the coil. A higher mass-power product and a larger diameter causes a stronger primary field. Reducing the number of turns and increasing the clamp voltage reduces the switch-off time of the transmitting current effectively. Increasing the cross-section of the wire reduces the power consumption, but greatly increases the coil's weight. The study of the receiving coil shows that the internal noise of the sensor is dominated by the thermal noise of the damping resistor. Reducing the bandwidth of the system and increasing the size of the coil reduces the internal noise effectively. The cross-sectional area and the distance between the sections of the coil have little effect on the internal noise. A less damped state can effectively reduce signal distortion. Finally, a portable TEM sensor with both a transmitting coil (constructed with a diameter, number of turns, and transmitting current of 0.5 m, 30, and 5 A, respectively) and a receiving coil (constructed with a length and resonant frequency of 5.6 cm and 50 kHz, respectively) was built. The agreement between experimental and calculated results confirms the theory used in the sensor design. The responses of an 82 mm mortar shell at different distances were measured and inverted by the differential evolution (DE) algorithm to verify system performance. Results show that the sensor designed in this study can not only detect the 82 mm mortar shell within 1.2 m effectively but also locate the target precisely.

Processing and characterization of superconducting solenoids made of Bi-2212/Ag-alloy multifilament round wire for high field magnet applications

NASA Astrophysics Data System (ADS)

Chen, Peng

As the only high temperature superconductor with round wire (RW) geometry, Bi2Sr2CaCu2O8+x (Bi-2212) superconducting wire has the advantages of being multi-filamentary, macroscopically isotropic and twistable. With overpressure (OP) processing techniques recently developed by our group at the National High Magnetic Field Laboratory (NHMFL), the engineering current density (Je) of Bi-2212 RW can be dramatically increased. For example, Je of more than 600 A/mm 2 (4.2 K and 20 T) is achieved after 100 bar OP processing. With these intrinsically beneficial properties and recent processing progress, Bi-2212 RW has become very attractive for high field magnet applications, especially for nuclear magnetic resonance (NMR) magnets and accelerator magnets etc. This thesis summarizes my graduate study on Bi-2212 solenoids for high field and high homogeneity NMR magnet applications, which mainly includes performance study of Bi-2212 RW insulations, 1 bar and OP processing study of Bi-2212 solenoids, and development of superconducting joints between Bi-2212 RW conductors. Electrical insulation is one of the key components of Bi-2212 coils to provide sufficient electrical standoff within coil winding pack. A TiO 2/polymer insulation offered by nGimat LLC was systematically investigated by differential thermal analysis (DTA), thermo-gravimetric analysis (TGA), scanning electron microscopy (SEM), dielectric property measurements, and transport critical current (Ic) property measurements. About 29% of the insulation by weight is polymer. When the Bi-2212 wire is fully heat treated, this decomposes with slow heating to 400 °C in flowing O2. After the full reaction, we found that the TiO2 did not degrade the critical current properties, adhered well to the conductor, and provided a breakdown voltage of more than 100 V. A Bi-2212 RW wound solenoid coil was built using this insulation being offered by nGimat LLC. The coil resistance was constant through coil winding, polymer burn-off and full coil reaction. The coil was successfully tested at the NHMFL generating 33.8 T combined magnetic field in a 31.2 T background field. Multiple quenches occurred safely, which also illustrates that the insulation provided sufficient dielectric standoff. For Bi-2212 RW with a typical as-drawn diameter of 1.0-1.5 mm, this 15 microm thick insulation allows a very high coil packing factor of ~0.74, whereas earlier alumino-silicate braid insulation only allows packing factors of 0.38-0.48. In addition to the commercial TiO2/polymer insulation, we have also investigated sol-gel based ceramic coatings through collaboration with Harran University and another TiO2 based insulation coating at the NHMFL. Since Bi-2212 superconducting coils employ the Wind-and-React (W&R) technology, there are some potential issues in processing Bi-2212 coils, in particular for coils with a large thermal mass and dense oxide insulation coating. For this study, several Bi-2212 test solenoids with an outer diameter (OD) of about 90 mm were built and heat treated in 1 bar flowing oxygen with deadweights applied so as to simulate large coil packs. After the heat treatment (HT), coils were epoxy impregnated and cut. Winding pack was checked using SEM in terms of conductor geometry and insulation. Some samples were extracted to measure transport critical current Ic and critical temperature Tc. The results are very promising: test coils presented low creep behavior after standard partial melt HT under mechanical load, and no Ic degradation was found due to the application of mechanical load, and no inadequate oxygenation issue was seen for thick coils with ceramic coating on the wire. However, coils were partially electrically shorted after 1 bar HT under mechanical load, and we believe that increasing insulation coating thickness is necessary. In addition, several small solenoids were manufactured to study OP processing of Bi-2212 coils. The preliminary results indicate that there are some gaps between turns due to densification of wires (~4% wire diameter reduction) during 50-100 bar OP processing, and the diameter shrinking of conductors will potentially lead to coil sagging. So far, we have developed some methods to solve the issue of coil sagging, such as using flexible coil flange to allow smooth sagging of winding pack during OP processing. We have also investigated electrical joints between Bi-2212 RW conductors, which include resistive joints and superconducting joints. For resistive Bi-2212 joints, we evaluated conventional diffusion bonding method and soldering method. In general, the joints (with 42 mm joint length) resistances are below 200 nO at 4.2 K and magnetic fields up to 13.5 T, and the effect of magnetoresistance is clearly present. In addition to resistive joints, we successfully developed a superconducting joint between Bi-2212 RW conductors for persistent current mode (PCM) operations. (Abstract shortened by UMI.).

Practical design of a 4 Tesla double-tuned RF surface coil for interleaved 1H and 23Na MRI of rat brain.

PubMed

Alecci, M; Romanzetti, S; Kaffanke, J; Celik, A; Wegener, H P; Shah, N J

2006-08-01

MRI is proving to be a very useful tool for sodium quantification in animal models of stroke, ischemia, and cancer. In this work, we present the practical design of a dual-frequency RF surface coil that provides (1)H and (23)Na images of the rat head at 4 T. The dual-frequency RF surface coil comprised of a large loop tuned to the (1)H frequency and a smaller co-planar loop tuned to the (23)Na frequency. The mutual coupling between the two loops was eliminated by the use of a trap circuit inserted in the smaller coil. This independent-loop design was versatile since it enabled a separate optimisation of the sensitivity and RF field distributions of the two coils. To allow for an easy extension of this simple double-tuned coil design to other frequencies (nuclei) and dimensions, we describe in detail the practical aspects of the workbench design and MRI testing using a phantom that mimics in vivo conditions. A comparison between our independent-loop, double-tuned coil and a single-tuned (23)Na coil of equal size obtained with a phantom matching in vivo conditions, showed a reduction of the (23)Na sensitivity (about 28 %) because of signal losses in the trap inductance. Typical congruent (1)H and (23)Na rat brain images showing good SNR ((23)Na: brain 7, ventricular cerebrospinal fluid 11) and spatial resolution ((23)Na: 1.25 x 1.25 x 5mm(3)) are also reported. The in vivo SNR values obtained with this coil were comparable to, if not better than, other contemporary designs in the literature.

Practical design of a 4 Tesla double-tuned RF surface coil for interleaved 1H and 23Na MRI of rat brain

NASA Astrophysics Data System (ADS)

Alecci, M.; Romanzetti, S.; Kaffanke, J.; Celik, A.; Wegener, H. P.; Shah, N. J.

2006-08-01

MRI is proving to be a very useful tool for sodium quantification in animal models of stroke, ischemia, and cancer. In this work, we present the practical design of a dual-frequency RF surface coil that provides 1H and 23Na images of the rat head at 4 T. The dual-frequency RF surface coil comprised of a large loop tuned to the 1H frequency and a smaller co-planar loop tuned to the 23Na frequency. The mutual coupling between the two loops was eliminated by the use of a trap circuit inserted in the smaller coil. This independent-loop design was versatile since it enabled a separate optimisation of the sensitivity and RF field distributions of the two coils. To allow for an easy extension of this simple double-tuned coil design to other frequencies (nuclei) and dimensions, we describe in detail the practical aspects of the workbench design and MRI testing using a phantom that mimics in vivo conditions. A comparison between our independent-loop, double-tuned coil and a single-tuned 23Na coil of equal size obtained with a phantom matching in vivo conditions, showed a reduction of the 23Na sensitivity (about 28 %) because of signal losses in the trap inductance. Typical congruent 1H and 23Na rat brain images showing good SNR ( 23Na: brain 7, ventricular cerebrospinal fluid 11) and spatial resolution ( 23Na: 1.25 × 1.25 × 5 mm 3) are also reported. The in vivo SNR values obtained with this coil were comparable to, if not better than, other contemporary designs in the literature.

Dryout occurrence in a helically coiled steam generator for nuclear power application

NASA Astrophysics Data System (ADS)

Santini, L.; Cioncolini, A.; Lombardi, C.; Ricotti, M.

2014-03-01

Dryout phenomena have been experimentally investigated in a helically coiled steam generator tube. The experiences carried out in the present work are part of a wide experimental program devoted to the study of a GEN III+ innovative nuclear power plant [1].The experimental facility consists in an electrically heated AISI 316L stainless steel coiled tube. The tube is 32 meters long, 12.53 mm of inner diameter, with a coil diameter of 1m and a pitch of 0.79 m, resulting in a total height of the steam generator of 8 meters. The thermo-hydraulics conditions for dryout investigations covered a spectrum of mass fluxes between 199 and 810 kg/m2s, the pressures ranges from 10.7 to 60.7 bar, heat fluxes between 43.6 to 209.3 kW/m2.Very high first qualities dryout, between 0.72 and 0.92, were found in the range of explored conditions, comparison of our results with literature available correlations shows the difficulty in predicting high qualities dryout in helical coils., immediately following the heading. The text should be set to 1.15 line spacing. The abstract should be centred across the page, indented 15 mm from the left and right page margins and justified. It should not normally exceed 200 words.

Calculation of the Area of Stochastic Layer for a Single-Null Divertor Tokamak with the Effects of Dipole Coil Using Method of Maps

NASA Astrophysics Data System (ADS)

Basemore, Alphonso; Ali, Halima; Watson, Michael; Punjabi, Alkesh

1996-11-01

We calculate the variation in area of the stochastic scrape-off layer of a single-null divertor tokamak resulting from the effects of an externally placed dipole coil using the Method of Maps (Punjabi A, Verma A and Boozer A, Phys Rev Lett), 69, 3322 (1992) and J Plasma Phys, 52, 91 (1994). The unperturbed magnetic topology is represented by the Symmetric Simple Map (Ali H, Watson M, Mayer C, Punjabi A and Boozer A, Bull Am Phys Soc), 40, 1855 (1995). The effects of the dipole coil are repesented by the Dipole Map (Ali H, Watson M, Punjabi A and Boozer A, Sherwood Mtg), paper 1C20 (1996). A single dipole coil is placed across from the X-point below the last good surface. The strength of the dipole perturbation and the distance of the coil from last good surface are varied. The area of the stochastic layer is calculated using the method of fractal dimension. This work is supported by US DOE OFES. Alphonso Basemore is a HU CFRT Summer Fusion High School Workshop scholar from Mount Tabor High School in North Carolina. He is supported by NASA under its NASA SharpPlus Program.

An accurate online calibration system based on combined clamp-shape coil for high voltage electronic current transformers

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

Li, Zhen-hua; Li, Hong-bin; Zhang, Zhi

Electronic transformers are widely used in power systems because of their wide bandwidth and good transient performance. However, as an emerging technology, the failure rate of electronic transformers is higher than that of traditional transformers. As a result, the calibration period needs to be shortened. Traditional calibration methods require the power of transmission line be cut off, which results in complicated operation and power off loss. This paper proposes an online calibration system which can calibrate electronic current transformers without power off. In this work, the high accuracy standard current transformer and online operation method are the key techniques. Basedmore » on the clamp-shape iron-core coil and clamp-shape air-core coil, a combined clamp-shape coil is designed as the standard current transformer. By analyzing the output characteristics of the two coils, the combined clamp-shape coil can achieve verification of the accuracy. So the accuracy of the online calibration system can be guaranteed. Moreover, by employing the earth potential working method and using two insulating rods to connect the combined clamp-shape coil to the high voltage bus, the operation becomes simple and safe. Tests in China National Center for High Voltage Measurement and field experiments show that the proposed system has a high accuracy of up to 0.05 class.« less

Design optimization of transmitting antennas for weakly coupled magnetic induction communication systems

PubMed Central

2017-01-01

This work focuses on the design of transmitting coils in weakly coupled magnetic induction communication systems. We propose several optimization methods that reduce the active, reactive and apparent power consumption of the coil. These problems are formulated as minimization problems, in which the power consumed by the transmitting coil is minimized, under the constraint of providing a required magnetic field at the receiver location. We develop efficient numeric and analytic methods to solve the resulting problems, which are of high dimension, and in certain cases non-convex. For the objective of minimal reactive power an analytic solution for the optimal current distribution in flat disc transmitting coils is provided. This problem is extended to general three-dimensional coils, for which we develop an expression for the optimal current distribution. Considering the objective of minimal apparent power, a method is developed to reduce the computational complexity of the problem by transforming it to an equivalent problem of lower dimension, allowing a quick and accurate numeric solution. These results are verified experimentally by testing a number of coil geometries. The results obtained allow reduced power consumption and increased performances in magnetic induction communication systems. Specifically, for wideband systems, an optimal design of the transmitter coil reduces the peak instantaneous power provided by the transmitter circuitry, and thus reduces its size, complexity and cost. PMID:28192463

Implant-specific follow-up imaging of treated intracranial aneurysms: TOF-MRA vs. metal artifact reduced intravenous flat panel computed tomography angiography (FPCTA).

PubMed

Hänsel, N H; Schubert, G A; Scholz, B; Nikoubashman, O; Othman, A E; Wiesmann, M; Pjontek, R; Brockmann, M A

2018-02-01

To compare the diagnostic quality of time-of-flight magnetic resonance angiography (TOF-MRA) and metal-artefact-reduction (MAR) flat-panel-detector computed tomography angiography (FPCTA) and to determine the imaging technique best suited for evaluation endovascular and surgically treated aneurysms. The image quality of TOF-MRA and MAR-FPCTA of 44 intracranial implants (coiling: n=20; clipping: n=15; coiling + stenting: n=9) in a patient cohort of 25 was evaluated by two independent readers. Images obtained using MAR-FPCTA (20 second scan time, 496 projections, intravenous contrast medium administration; Artis Zee, Siemens Healthcare, Forchheim) were compared with TOF-MRA-images (1.5 or 3 T). Nominal data were analysed using McNemar's chi-square test and ordinal variables using the Wilcoxon rank test. Compared to TOF-MRA, MAR-FPCTA was significantly better suited to detect aneurysm remnants and to evaluate parent vessels after clipping (p<0.01). For coil packages >160 mm 3 , TOF-MRA provided significantly better assessment than MAR-FPCTA (p<0.01). For small coil packages (<160 mm 3 ), no significant difference between TOF-MRA and MAR-FPCTA (p=0.232) was observed. For different clip sizes (cut-off 492 mm 3 ) likewise no significant differences were found. The interobserver comparison showed high interrater agreement. MAR-FPCTA is significantly better suited for follow-up examinations of clipped aneurysms, whereas for larger coil packages TOF-MRA is preferable. Smaller coil packages can be analysed using MAR-FPCTA or TOF-MRA. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Endovascular Catheter for Magnetic Navigation under MR Imaging Guidance: Evaluation of Safety in Vivo at 1.5T

PubMed Central

Hetts, S.W.; Saeed, M.; Martin, A.J.; Evans, L.; Bernhardt, A.F.; Malba, V.; Settecase, F.; Do, L.; Yee, E.J.; Losey, A.; Sincic, R.; Roy, S.; Arenson, R.L.; Wilson, M.W.

2013-01-01

BACKGROUND AND PURPOSE: Endovascular navigation under MR imaging guidance can be facilitated by a catheter with steerable microcoils on the tip. Not only do microcoils create visible artifacts allowing catheter tracking, but also they create a small magnetic moment permitting remote-controlled catheter tip deflection. A side product of catheter tip electrical currents, however, is the heat that might damage blood vessels. We sought to determine the upper boundary of electrical currents safely usable at 1.5T in a coil-tipped microcatheter system. MATERIALS AND METHODS: Alumina tubes with solenoid copper coils were attached to neurovascular microcatheters with heat shrink-wrap. Catheters were tested in carotid arteries of 8 pigs. The catheters were advanced under x-ray fluoroscopy and MR imaging. Currents from 0 mA to 700 mA were applied to test heating and potential vascular damage. Postmortem histologic analysis was the primary endpoint. RESULTS: Several heat-mitigation strategies demonstrated negligible vascular damage compared with control arteries. Coil currents ≤300 mA resulted in no damage (0/58 samples) compared with 9 (25%) of 36 samples for > 300-mA activations (P = .0001). Tip coil activation ≤1 minute and a proximal carotid guide catheter saline drip > 2 mL/minute also had a nonsignificantly lower likelihood of vascular damage. For catheter tip coil activations ≤300 mA for ≤1 minute in normal carotid flow, 0 of 43 samples had tissue damage. CONCLUSIONS: Activations of copper coils at the tip of microcatheters at low currents in 1.5T MR scanners can be achieved without significant damage to blood vessel walls in a controlled experimental setting. Further optimization of catheter design and procedure protocols is necessary for safe remote control magnetic catheter guidance. PMID:23846795

Optimized 14 + 1 receive coil array and position system for 3D high-resolution MRI of dental and maxillomandibular structures.

PubMed

Sedlacik, Jan; Kutzner, Daniel; Khokale, Arun; Schulze, Dirk; Fiehler, Jens; Celik, Turgay; Gareis, Daniel; Smeets, Ralf; Friedrich, Reinhard E; Heiland, Max; Assaf, Alexandre T

2016-01-01

The purpose of this study was to design, build and test a multielement receive coil array and position system, which is optimized for three-dimensional (3D) high-resolution dental and maxillomandibular MRI with high patient comfort. A 14 + 1 coil array and positioning system, allowing easy handling by the technologists, reproducible positioning of the patients and high patient comfort, was tested with three healthy volunteers using a 3.0-T MRI machine (Siemens Skyra; Siemens Medical Solutions, Erlangen, Germany). High-resolution 3D T1 weighted, water excitation T1 weighted and fat-saturated T2 weighted imaging sequences were scanned, and 3D image data were reformatted in different orientations and curvatures to aid diagnosis. The high number of receiving coils and the comfortable positioning of the coil array close to the patient's face provided a high signal-to-noise ratio and allowed high quality, high resolution, 3D image data to be acquired within reasonable scan times owing to the possibility of parallel image acquisition acceleration. Reformatting the isotropic 3D image data in different views is helpful for diagnosis, e.g. panoramic reconstruction. The visibility of soft tissues such as the mandibular canal, nutritive canals and periodontal ligaments was exquisite. The optimized MRI receive coil array and positioning system for dental and oral-maxillofacial imaging provides a valuable tool for detecting and diagnosing pathologies in dental and oral-maxillofacial structures while avoiding radiation dose. The high patient comfort, as achieved by our design, is very crucial, since image artefacts due to movement or failing to complete the examination jeopardize the diagnostic value of MRI examinations.

Characteristics and performance of a superconducting bumpy-torus magnet facility for plasma research

NASA Technical Reports Server (NTRS)

Roth, J. R.; Holmes, A. D.; Keller, T. A.; Krawczonek, W. M.

1973-01-01

The NASA Lewis bumpy-torus facility consists of 12 superconducting coils, each 19 cm i.d. and capable of 3.0 T on its axis. The coils are equally spaced around a toroidal array with a major diameter of 1.52 m; they are mounted with the major axis of the torus vertical in a single vacuum tank 2.6 m in diameter. Tests of the facility mapped out its magnetic, cryogenic, vacuum, mechanical, and electrical performance. The design value of the maximum magnetic field on the magnetic axis, 3.0 T, was reached and exceeded. A maximum magnetic field of 3.23 T was held for a period of 60 minutes. When the coils were charged to a maximum magnetic field of 3.35 T, the coil system went normal without apparent damage or degradation of performance.

Computer-Generated Diagrams for the Classroom.

ERIC Educational Resources Information Center

Carle, Mark A.; Greenslade, Thomas B., Jr.

1986-01-01

Describes 10 computer programs used to draw diagrams usually drawn on chalkboards, such as addition of three vectors, vector components, range of a projectile, lissajous figures, beats, isotherms, Snell's law, waves passing through a lens, magnetic field due to Helmholtz coils, and three curves. Several programming tips are included. (JN)

Research on Annular Frictional Pressure Loss of Hydraulic-Fracturing in Buckling Coiled Tubing

NASA Astrophysics Data System (ADS)

Liu, Bin; Cai, Meng; Li, Junliang; Xu, Yongquan; Wang, Peng

2018-01-01

Compared with conventional hydraulic fracturing, coiled tubing (CT) annular delivery sand fracturing technology is a new method to enhance the recovery ratio of low permeability reservoir. Friction pressure loss through CT has been a concern in fracturing. The small diameter of CT limits the cross-sectional area open to flow, therefore, to meet large discharge capacity, annular delivery sand technology has been gradually developed in oilfield. Friction pressure is useful for determining the required pump horsepower and fracturing construction design programs. Coiled tubing can buckle when the axial compressive load acting on the tubing is greater than critical buckling load, then the geometry shape of annular will change. Annular friction pressure loss elevates dramatically with increasing of discharge capacity, especially eccentricity and CT buckling. Despite the frequency occurrence of CT buckling in oilfield operations, traditionally annular flow frictional pressure loss considered concentric and eccentric annuli, not discussing the effects of for discharge capacity and sand ratio varying degree of CT buckling. The measured data shows that the factors mentioned above cannot be ignored in the prediction of annular pressure loss. It is necessary to carry out analysis of annulus flow pressure drop loss in coiled tubing annular with the methods of theoretical analysis and numerical simulation. Coiled tubing buckling has great influence on pressure loss of fracturing fluid. Therefore, the correlations have been developed for turbulent flow of Newtonian fluids and Two-phase flow (sand-liquid), and that improve the friction pressure loss estimation in coiled tubing operations involving a considerable level of buckling. Quartz sand evidently increases pressure loss in buckling annular, rising as high as 40%-60% more than fresh water. Meanwhile, annulus flow wetted perimeter increases with decreasing helical buckling pitch of coiled tubing, therefore, the annulus flow frictional pressure loss rapidly increases with decreasing helical buckling pitch. The research achievement provides theoretical guidance for coiled tubing annular delivery sand fracturing operation and design.

Mechanical qualification of the support structure for MQXF, the Nb 3Sn low-β quadrupole for the high luminosity LHC

DOE PAGES

Juchno, M.; Ambrosio, G.; Anerella, M.; ...

2016-01-26

Within the scope of the High Luminosity LHC project, the collaboration between CERN and U.S. LARP is developing new low-β quadrupoles using the Nb 3Sn superconducting technology for the upgrade of the LHC interaction regions. The magnet support structure of the first short model was designed and two units were fabricated and tested at CERN and at LBNL. The structure provides the preload to the collars-coils subassembly by an arrangement of outer aluminum shells pre-tensioned with water-pressurized bladders. For the mechanical qualification of the structure and the assembly procedure, superconducting coils were replaced with solid aluminum “dummy coils”, the structuremore » was preloaded at room temperature, and then cooled-down to 77 K. Mechanical behavior of the magnet structure was monitored with the use of strain gauges installed on the aluminum shells, the dummy coils and the axial preload system. As a result, this paper reports on the outcome of the assembly and the cool-down tests with dummy coils, which were performed at CERN and at LBNL, and presents the strain gauge measurements compared to the 3D finite element model predictions.« less

Method and apparatus for deflection measurements using eddy current effects

NASA Astrophysics Data System (ADS)

Chern, Engmin J.

1993-05-01

A method and apparatus for inserting and moving a sensing assembly with a mechanical positioning assembly to a desired remote location of a surface of a specimen under test and measuring angle and/or deflection by sensing the change in the impedance of at least one sensor coil located in a base plate which has a rotatable conductive plate pivotally mounted thereon so as to uncover the sensor coil(s) whose impedance changes as a function of deflection away from the center line of the base plate in response to the movement of the rotator plate when contacting the surface of the specimen under test is presented. The apparatus includes the combination of a system controller, a sensing assembly, an eddy current impedance measuring apparatus, and a mechanical positioning assembly driven by the impedance measuring apparatus to position the sensing assembly at a desired location of the specimen.

High temperature superconducting synchronous motor design and test

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

Schiferl, R.; Zhang, B.; Shoykhet, B.

1996-10-01

High horsepower synchronous motors with high temperature superconducting (HTS) field windings offer the potential to cut motor operating losses in half compared to conventional energy efficient induction motors available today. The design, construction and test of a prototype, air core, synchronous motor with helium gas cooled HTS field coils will be described in this paper. The work described is part of a US Department of Energy, Superconductivity Partnership Initiative award. The motor uses a modified conventional motor armature combined with a vacuum insulated rotor that contains the four racetrack-shaped HTS field coils. The rotor is cooled by helium gas somore » that the HTS coils operate at a temperature of 30 K. This paper provides a status report on HTS motor research and development at Reliance Lab., Rockwell Automation that will lead to commercial HTS motors for utility and industrial applications.« less

Method and apparatus for deflection measurements using eddy current effects

NASA Technical Reports Server (NTRS)

Chern, Engmin J. (Inventor)

1993-01-01

A method and apparatus for inserting and moving a sensing assembly with a mechanical positioning assembly to a desired remote location of a surface of a specimen under test and measuring angle and/or deflection by sensing the change in the impedance of at least one sensor coil located in a base plate which has a rotatable conductive plate pivotally mounted thereon so as to uncover the sensor coil(s) whose impedance changes as a function of deflection away from the center line of the base plate in response to the movement of the rotator plate when contacting the surface of the specimen under test is presented. The apparatus includes the combination of a system controller, a sensing assembly, an eddy current impedance measuring apparatus, and a mechanical positioning assembly driven by the impedance measuring apparatus to position the sensing assembly at a desired location of the specimen.

A conceptual design study of a high temperature solar thermal receiver (added tasks 6 and 7)

NASA Technical Reports Server (NTRS)

Robertson, C. S.; Mccreight, L. R.; Gatti, A.; Semon, H. W.

1980-01-01

The key component of this concept is a coiled tube of silicon nitride which acts as a heat exchanger appears to be ideal from the standpoint of utilizing structural ceramics at around 2500 F under severe thermal shock conditions. However the size and configuration of this coil are beyond the state of the art for fabricating such materials as silicon nitride and carbide. A two-task program to develop and demonstrate the feasibility of extruding and forming a section of thin walled silicon nitride tubing was undertaken as an addition to the original program. A promising polyvinyl butyral-based binder lubricant was identified. Fourteen full size extrusion experiments were conducted. Two trial firings of 1-1/4 turn helices were made.

From synthetic coiled coils to functional proteins: automated design of a receptor for the calmodulin-binding domain of calcineurin.

PubMed

Ghirlanda, G; Lear, J D; Lombardi, A; DeGrado, W F

1998-08-14

A series of synthetic receptors capable of binding to the calmodulin-binding domain of calcineurin (CN393-414) was designed, synthesized and characterized. The design was accomplished by docking CN393-414 against a two-helix receptor, using an idealized three-stranded coiled coil as a starting geometry. The sequence of the receptor was chosen using a side-chain re-packing program, which employed a genetic algorithm to select potential binders from a total of 7.5x10(6) possible sequences. A total of 25 receptors were prepared, representing 13 sequences predicted by the algorithm as well as 12 related sequences that were not predicted. The receptors were characterized by CD spectroscopy, analytical ultracentrifugation, and binding assays. The receptors predicted by the algorithm bound CN393-414 with apparent dissociation constants ranging from 0.2 microM to >50 microM. Many of the receptors that were not predicted by the algorithm also bound to CN393-414. Methods to circumvent this problem and to improve the automated design of functional proteins are discussed. Copyright 1998 Academic Press

Solving coiled-coil protein structures

DOE PAGES

Dauter, Zbigniew

2015-02-26

With the availability of more than 100,000 entries stored in the Protein Data Bank (PDB) that can be used as search models, molecular replacement (MR) is currently the most popular method of solving crystal structures of macromolecules. Significant methodological efforts have been directed in recent years towards making this approach more powerful and practical. This resulted in the creation of several computer programs, highly automated and user friendly, that are able to successfully solve many structures even by researchers who, although interested in structures of biomolecules, are not very experienced in crystallography.

Resonator coiling in thermoacoustic engines

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

Olson, J.R.; Swift, G.W.

1995-11-01

Coiling the resonator of a thermoacoustic engine is one way to try to minimize the engine`s size. However, flow in bent pipes is known to alter the fluid flow pattern because of centrifugal forces. Theory and measurements will be presented on the energy dissipation caused by oscillating flow in curved pipes. Measurements have been taken using free oscillations of liquids in U-tubes, and using a thermoacoustic engine with straight and bent resonators. [Work supported by the TTI program of the US Department of Energy, and by the Tektronix Corporation.

Experimental evaluation of a high performance superconducting torquer

NASA Astrophysics Data System (ADS)

Goldie, James H.; Avakian, Kevin M.; Downer, James R.; Gerver, Michael; Gondhalekar, Vijay; Johnson, Bruce G.

The high performance superconducting torquer (HPSCT) was designed to slew a large inertia in one degree of freedom with a double versine torque profile, a profile used for pointing applications which minimizes the exciting of structural resonances. The program culminated with the successful demonstration of closed loop torque control, following a desired double versine torque profile to an accuracy of approximately 1 percent of the peak torque of the profile. The targeted double versine possessed a peak torque which matches the torque capacity of the Sperry M4500 CMG (controlled moment gyro). The research provided strong evidence of the feasibility of an advanced concept CMG which would use cryoresistive control coils in conjunction with an electromagnetically suspended rotor and superconducting source coil. The cryoresistive coils interact with the superconducting solenoid to develop the desired torque and, in addition, the required suspension forces.

Characterization of the onboard imaging unit for the first clinical magnetic resonance image guided radiation therapy system

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

Hu, Yanle, E-mail: Hu.Yanle@mayo.edu; Rankine, Leith; Green, Olga L.

Purpose: To characterize the performance of the onboard imaging unit for the first clinical magnetic resonance image guided radiation therapy (MR-IGRT) system. Methods: The imaging performance characterization included four components: ACR (the American College of Radiology) phantom test, spatial integrity, coil signal to noise ratio (SNR) and uniformity, and magnetic field homogeneity. The ACR phantom test was performed in accordance with the ACR phantom test guidance. The spatial integrity test was evaluated using a 40.8 × 40.8 × 40.8 cm{sup 3} spatial integrity phantom. MR and computed tomography (CT) images of the phantom were acquired and coregistered. Objects were identifiedmore » around the surfaces of 20 and 35 cm diameters of spherical volume (DSVs) on both the MR and CT images. Geometric distortion was quantified using deviation in object location between the MR and CT images. The coil SNR test was performed according to the national electrical manufacturers association (NEMA) standards MS-1 and MS-9. The magnetic field homogeneity test was measured using field camera and spectral peak methods. Results: For the ACR tests, the slice position error was less than 0.10 cm, the slice thickness error was less than 0.05 cm, the resolved high-contrast spatial resolution was 0.09 cm, the resolved low-contrast spokes were more than 25, the image intensity uniformity was above 93%, and the percentage ghosting was less than 0.22%. All were within the ACR recommended specifications. The maximum geometric distortions within the 20 and 35 cm DSVs were 0.10 and 0.18 cm for high spatial resolution three-dimensional images and 0.08 and 0.20 cm for high temporal resolution two dimensional cine images based on the distance-to-phantom-center method. The average SNR was 12.0 for the body coil, 42.9 for the combined torso coil, and 44.0 for the combined head and neck coil. Magnetic field homogeneities at gantry angles of 0°, 30°, 60°, 90°, and 120° were 23.55, 20.43, 18.76, 19.11, and 22.22 ppm, respectively, using the field camera method over the 45 cm DSV. Conclusions: The onboard imaging unit of the first commercial MR-IGRT system meets ACR, NEMA, and vendor specifications.« less

Characterization of the onboard imaging unit for the first clinical magnetic resonance image guided radiation therapy system.

PubMed

Hu, Yanle; Rankine, Leith; Green, Olga L; Kashani, Rojano; Li, H Harold; Li, Hua; Nana, Roger; Rodriguez, Vivian; Santanam, Lakshmi; Shvartsman, Shmaryu; Victoria, James; Wooten, H Omar; Dempsey, James F; Mutic, Sasa

2015-10-01

To characterize the performance of the onboard imaging unit for the first clinical magnetic resonance image guided radiation therapy (MR-IGRT) system. The imaging performance characterization included four components: ACR (the American College of Radiology) phantom test, spatial integrity, coil signal to noise ratio (SNR) and uniformity, and magnetic field homogeneity. The ACR phantom test was performed in accordance with the ACR phantom test guidance. The spatial integrity test was evaluated using a 40.8 × 40.8 × 40.8 cm(3) spatial integrity phantom. MR and computed tomography (CT) images of the phantom were acquired and coregistered. Objects were identified around the surfaces of 20 and 35 cm diameters of spherical volume (DSVs) on both the MR and CT images. Geometric distortion was quantified using deviation in object location between the MR and CT images. The coil SNR test was performed according to the national electrical manufacturers association (NEMA) standards MS-1 and MS-9. The magnetic field homogeneity test was measured using field camera and spectral peak methods. For the ACR tests, the slice position error was less than 0.10 cm, the slice thickness error was less than 0.05 cm, the resolved high-contrast spatial resolution was 0.09 cm, the resolved low-contrast spokes were more than 25, the image intensity uniformity was above 93%, and the percentage ghosting was less than 0.22%. All were within the ACR recommended specifications. The maximum geometric distortions within the 20 and 35 cm DSVs were 0.10 and 0.18 cm for high spatial resolution three-dimensional images and 0.08 and 0.20 cm for high temporal resolution two dimensional cine images based on the distance-to-phantom-center method. The average SNR was 12.0 for the body coil, 42.9 for the combined torso coil, and 44.0 for the combined head and neck coil. Magnetic field homogeneities at gantry angles of 0°, 30°, 60°, 90°, and 120° were 23.55, 20.43, 18.76, 19.11, and 22.22 ppm, respectively, using the field camera method over the 45 cm DSV. The onboard imaging unit of the first commercial MR-IGRT system meets ACR, NEMA, and vendor specifications.

Preliminary Upper Estimate of Peak Currents in Transcranial Magnetic Stimulation at Distant Locations from a TMS Coil

PubMed Central

Makarov, Sergey N.; Yanamadala, Janakinadh; Piazza, Matthew W.; Helderman, Alex M.; Thang, Niang S.; Burnham, Edward H.; Pascual-Leone, Alvaro

2016-01-01

Goals Transcranial magnetic stimulation (TMS) is increasingly used as a diagnostic and therapeutic tool for numerous neuropsychiatric disorders. The use of TMS might cause whole-body exposure to undesired induced currents in patients and TMS operators. The aim of the present study is to test and justify a simple analytical model known previously, which may be helpful as an upper estimate of eddy current density at a particular distant observation point for any body composition and any coil setup. Methods We compare the analytical solution with comprehensive adaptive mesh refinement-based FEM simulations of a detailed full-body human model, two coil types, five coil positions, about 100,000 observation points, and two distinct pulse rise times, thus providing a representative number of different data sets for comparison, while also using other numerical data. Results Our simulations reveal that, after a certain modification, the analytical model provides an upper estimate for the eddy current density at any location within the body. In particular, it overestimates the peak eddy currents at distant locations from a TMS coil by a factor of 10 on average. Conclusion The simple analytical model tested in the present study may be valuable as a rapid method to safely estimate levels of TMS currents at different locations within a human body. Significance At present, safe limits of general exposure to TMS electric and magnetic fields are an open subject, including fetal exposure for pregnant women. PMID:26685221

A persistent-mode 0.5 T solid-nitrogen-cooled MgB2 magnet for MRI

PubMed Central

Ling, Jiayin; Voccio, John P.; Hahn, Seungyong; Qu, Timing; Bascuñán, Juan; Iwasa, Yukikazu

2017-01-01

This paper presents construction details and test results of a persistent-mode 0.5-T MgB2 magnet developed at the Francis Bitter Magnet Lab, MIT. The magnet, of 276-mm inner diameter and 290-mm outer diameter, consisted of a stack of 8 solenoidal coils with a total height of 460 mm. Each coil was wound with monofilament MgB2 wire, equipped with a persistent-current switch and terminated with a superconducting joint, forming an individual superconducting loop. Resistive solder joints connected the 8 coils in series. The magnet, after being integrated into a testing system, immersed in solid nitrogen, was operated in a temperature range of 10–13 K. A two-stage cryocooler was deployed to cool a radiation shield and the cold mass that included mainly ~60 kg of solid nitrogen and the magnet. The solid nitrogen was capable of providing a uniform and stable cryogenic environment to the magnet. The magnet sustained a 0.47-T magnetic field at its center persistently in a range of 10–13 K. The current in each coil was inversely calculated from the measured field profile to determine the performance of each coil in persistent-mode operation. Persistent-current switches were successfully operated in solid nitrogen for ramping the magnet. They were also designed to absorb magnetic energy in a protection mechanism; its effectiveness was evaluated in an induced quench. PMID:28966476

Multiple degree-of-freedom force and moment measurement for static propulsion testing using magnetic suspension technology

NASA Technical Reports Server (NTRS)

Stuart, Keith; Bartosh, Blake

1993-01-01

Innovative Information Systems (IIS), Inc. is in the process of designing and fabricating a high bandwidth force and moment measuring device (i.e. the Magnetic Thruster Test Stand). This device will use active magnetic suspension to allow direct measurements of the forces and torques generated by the rocket engines of the missile under test. The principle of operation of the Magnetic Thruster Test Stand (MTTS) is based on the ability to perform very precise, high bandwidth force and position measurements on an object suspended in a magnetic field. This ability exists due to the fact that the digital servo control mechanism that performs the magnetic suspension uses high bandwidth (10 kHz) position data (via an eddy-current proximity sensor) to determine the amount of force required to maintain stable suspension at a particular point. This force is converted into required electromagnet coil current, which is then output to a current amplifier driving the coils. A discussion of how the coil current and magnetic gap distance (the distance between the electromagnet and the object being suspended) is used to determine the forces being applied from the suspended assembly is presented.

A Novel Transient Fault Current Sensor Based on the PCB Rogowski Coil for Overhead Transmission Lines

PubMed Central

Liu, Yadong; Xie, Xiaolei; Hu, Yue; Qian, Yong; Sheng, Gehao; Jiang, Xiuchen

2016-01-01

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. PMID:27213402

Finite element coiled cochlea model

NASA Astrophysics Data System (ADS)

Isailovic, Velibor; Nikolic, Milica; Milosevic, Zarko; Saveljic, Igor; Nikolic, Dalibor; Radovic, Milos; Filipović, Nenad

2015-12-01

Cochlea is important part of the hearing system, and thanks to special structure converts external sound waves into neural impulses which go to the brain. Shape of the cochlea is like snail, so geometry of the cochlea model is complex. The simplified cochlea coiled model was developed using finite element method inside SIFEM FP7 project. Software application is created on the way that user can prescribe set of the parameters for spiral cochlea, as well as material properties and boundary conditions to the model. Several mathematical models were tested. The acoustic wave equation for describing fluid in the cochlea chambers - scala vestibuli and scala timpani, and Newtonian dynamics for describing vibrations of the basilar membrane are used. The mechanical behavior of the coiled cochlea was analyzed and the third chamber, scala media, was not modeled because it does not have a significant impact on the mechanical vibrations of the basilar membrane. The obtained results are in good agreement with experimental measurements. Future work is needed for more realistic geometry model. Coiled model of the cochlea was created and results are compared with initial simplified coiled model of the cochlea.

Design and Construction of Versatile Experiment Spherical Torus (VEST) at Seoul National University

NASA Astrophysics Data System (ADS)

An, Younghwa; Chung, Kyoung-Jae; Jung, Bongki; Lee, Hyunyeong; Sung, Choongki; Kim, Hyun-Seok; Na, Yong-Su; Hwang, Yong-Seok

2011-10-01

A new spherical torus, named as VEST (Versatile Experiment Spherical Torus), has been built at Seoul National University to investigate versatile research topics such as double null merging start-up, divertor engineering and non-inductive current drive. VEST is characterized by two partial solenoid coils installed at both vertical ends of a center stack, which will be used for double null merging start-up schemes. A poloidal field (PF) coil system including the partial solenoids for break-down and a long solenoid for the sustainment of merged plasma has been designed by solving circuit equations for the PF coils and vacuum vessel elements in consideration of required volt-second, null configuration and eddy current. To supply required currents to the PF coils and solenoids, power supplies based on double-swing circuit have been designed and fabricated with capacitor banks and thyristor switch assemblies. Also a power supply utilizing cost-effective commercial batteries has been developed for toroidal field(TF) coils. Detailed descriptions on the design of VEST and some initial test results will be presented.

Challenges and status of ITER conductor production

NASA Astrophysics Data System (ADS)

Devred, A.; Backbier, I.; Bessette, D.; Bevillard, G.; Gardner, M.; Jong, C.; Lillaz, F.; Mitchell, N.; Romano, G.; Vostner, A.

2014-04-01

Taking the relay of the large Hadron collider (LHC) at CERN, ITER has become the largest project in applied superconductivity. In addition to its technical complexity, ITER is also a management challenge as it relies on an unprecedented collaboration of seven partners, representing more than half of the world population, who provide 90% of the components as in-kind contributions. The ITER magnet system is one of the most sophisticated superconducting magnet systems ever designed, with an enormous stored energy of 51 GJ. It involves six of the ITER partners. The coils are wound from cable-in-conduit conductors (CICCs) made up of superconducting and copper strands assembled into a multistage cable, inserted into a conduit of butt-welded austenitic steel tubes. The conductors for the toroidal field (TF) and central solenoid (CS) coils require about 600 t of Nb3Sn strands while the poloidal field (PF) and correction coil (CC) and busbar conductors need around 275 t of Nb-Ti strands. The required amount of Nb3Sn strands far exceeds pre-existing industrial capacity and has called for a significant worldwide production scale up. The TF conductors are the first ITER components to be mass produced and are more than 50% complete. During its life time, the CS coil will have to sustain several tens of thousands of electromagnetic (EM) cycles to high current and field conditions, way beyond anything a large Nb3Sn coil has ever experienced. Following a comprehensive R&D program, a technical solution has been found for the CS conductor, which ensures stable performance versus EM and thermal cycling. Productions of PF, CC and busbar conductors are also underway. After an introduction to the ITER project and magnet system, we describe the ITER conductor procurements and the quality assurance/quality control programs that have been implemented to ensure production uniformity across numerous suppliers. Then, we provide examples of technical challenges that have been encountered and we present the status of ITER conductor production worldwide.

Mechanical performance evaluation of the CFETR central solenoid model coil design

NASA Astrophysics Data System (ADS)

Liu, Xiaogang; Wang, Zhaoliang; Ren, Yong; Li, Junjun; Yin, Dapeng; Li, Lei; Gao, Xiang; Wu, Yu

2018-01-01

The Chinese Fusion Engineering Test Reactor (CFETR) Central Solenoid Model Coil is being fabricated by the Institute of Plasma Physics Chinese Academy of Sciences. The Model Coil is comprised of Nb3Sn and NbTi modules held together by a preload structure. It will operate at 4.5 K to produce a peak field of 12 T at 48 kA. In order to investigate the feasibility and integrity of the Model Coil design before its manufacturing, the mechanical performance has been evaluated for the room temperature preload, 4.5 K stand-by and 48 kA operating conditions. A 1/15 3D detailed model that consists of jackets, insulations, bladders, buffers and preload structure, is constructed and simulated using the coupled structural-thermal-electromagnetic solver of ANSYS. In contrary to a smeared winding pack model, our analysis with the detailed model can directly and precisely simulate the differential thermal contraction effect of the preload structure, jacket and insulations, as well as the electromagnetic load acting on the jacket. The detailed deformation and stress behaviors of the Model Coil are illustrated and discussed. The results indicate that the final design of the CFETR Central Solenoid Model Coil is reasonably conservative and satisfy the design criteria.

Performance of a 10-kJ SMES model cooled by liquid hydrogen thermo-siphon flow for ASPCS study

NASA Astrophysics Data System (ADS)

Makida, Y.; Shintomi, T.; Hamajima, T.; Ota, N.; Katsura, M.; Ando, K.; Takao, T.; Tsuda, M.; Miyagi, D.; Tsujigami, H.; Fujikawa, S.; Hirose, J.; Iwaki, K.; Komagome, T.

2015-12-01

We propose a new electrical power storage and stabilization system, called an Advanced Superconducting Power Conditioning System (ASPCS), which consists of superconducting magnetic energy storage (SMES) and hydrogen energy storage, converged on a liquid hydrogen station for fuel cell vehicles. A small 10- kJ SMES system, in which a BSCCO coil cooled by liquid hydrogen was installed, was developed to create an experimental model of an ASPCS. The SMES coil is conductively cooled by liquid hydrogen flow through a thermo-siphon line under a liquid hydrogen buffer tank. After fabrication of the system, cooldown tests were carried out using liquid hydrogen. The SMES coil was successfully charged up to a nominal current of 200 A. An eddy current loss, which was mainly induced in pure aluminum plates pasted onto each pancake coils for conduction cooling, was also measured.

Construction of a Chassis for a Tripartite Protein-Based Molecular Motor.

PubMed

Small, Lara S R; Bruning, Marc; Thomson, Andrew R; Boyle, Aimee L; Davies, Roberta B; Curmi, Paul M G; Forde, Nancy R; Linke, Heiner; Woolfson, Derek N; Bromley, Elizabeth H C

2017-06-16

Improving our understanding of biological motors, both to fully comprehend their activities in vital processes, and to exploit their impressive abilities for use in bionanotechnology, is highly desirable. One means of understanding these systems is through the production of synthetic molecular motors. We demonstrate the use of orthogonal coiled-coil dimers (including both parallel and antiparallel coiled coils) as a hub for linking other components of a previously described synthetic molecular motor, the Tumbleweed. We use circular dichroism, analytical ultracentrifugation, dynamic light scattering, and disulfide rearrangement studies to demonstrate the ability of this six-peptide set to form the structure designed for the Tumbleweed motor. The successful formation of a suitable hub structure is both a test of the transferability of design rules for protein folding as well as an important step in the production of a synthetic protein-based molecular motor.

Design and Testing of a Small Inductive Pulsed Plasma Thruster

NASA Technical Reports Server (NTRS)

Martin, Adam K.; Eskridge, Richard H.; Dominguez, Alexandra; Polzin, Kurt A.; Riley, Daniel P.; Kimberlin, Adam C.

2015-01-01

The design and testing of a small inductive pulsed plasma thruster (IPPT), shown in Fig. 1 with all the major subsystems required for a thruster of this kind are described. Thrust measurements and imaging of the device operated in rep-rated mode are presented to quantify the performance envelope of the device. The small IPPT described in this paper was designed to serve as a test-bed for the pulsed gas-valves and solid-state switches required for a IPPTs. A modular design approach was used to permit future modifications and upgrades. The thruster consists of the following sub-systems: a) a multi-turn, spiral-wound acceleration coil (27 cm o.d., 10 cm i.d.) driven by a 10 microFarad capacitor and switched with a high-voltage thyristor, b) a fast pulsed gas-valve, and c.) a glow-discharge pre-ionizer (PI) circuit. The acceleration-coil circuit may be operated at voltages up to 4 kV (the thyristor limit is 4.5 kV). The device may be operated at rep-rates up to 30 Hz with the present gas-valve. Thrust measurements and imaging of the device operated in rep-rated mode will be presented. The pre-ionizer consists of a 0.3 microFarad capacitor charged to 4 kV and connected to two annular stainless-steel electrodes bounding the area of the coil-face. The 4 kV potential is held across them and when the gas is puffed in over the coil, the PI circuit is completed, and a plasma is formed. Even at the less than optimal base-pressure in the chamber (approximately 5 × 10(exp -4) torr), the PI held-off the applied voltage, and only discharged upon command. For a capacitor charge of 2 kV the peak coil current is 4.1 kA, and during this pulse a very bright discharge (much brighter than from the PI alone) was observed (see Fig. 2). Interestingly, for discharges at this charge voltage the PI was not required as the current rise rate, dI/dt, of the coil itself was sufficient to ionize the gas.

CSI 3.0: a web server for identifying secondary and super-secondary structure in proteins using NMR chemical shifts

PubMed Central

Hafsa, Noor E.; Arndt, David; Wishart, David S.

2015-01-01

The Chemical Shift Index or CSI 3.0 (http://csi3.wishartlab.com) is a web server designed to accurately identify the location of secondary and super-secondary structures in protein chains using only nuclear magnetic resonance (NMR) backbone chemical shifts and their corresponding protein sequence data. Unlike earlier versions of CSI, which only identified three types of secondary structure (helix, β-strand and coil), CSI 3.0 now identifies total of 11 types of secondary and super-secondary structures, including helices, β-strands, coil regions, five common β-turns (type I, II, I′, II′ and VIII), β hairpins as well as interior and edge β-strands. CSI 3.0 accepts experimental NMR chemical shift data in multiple formats (NMR Star 2.1, NMR Star 3.1 and SHIFTY) and generates colorful CSI plots (bar graphs) and secondary/super-secondary structure assignments. The output can be readily used as constraints for structure determination and refinement or the images may be used for presentations and publications. CSI 3.0 uses a pipeline of several well-tested, previously published programs to identify the secondary and super-secondary structures in protein chains. Comparisons with secondary and super-secondary structure assignments made via standard coordinate analysis programs such as DSSP, STRIDE and VADAR on high-resolution protein structures solved by X-ray and NMR show >90% agreement between those made with CSI 3.0. PMID:25979265

Dual levitated coils for antihydrogen production

NASA Astrophysics Data System (ADS)

Wofford, J. D.; Ordonez, C. A.

2013-04-01

Two coaxial superconducting magnetic coils that carry currents in the same direction and that are simultaneously levitated may serve for antihydrogen plasma confinement. The configuration may be suitable for use by a collaboration at the CERN Antiproton Decelerator facility to test fundamental symmetries between the properties of hydrogen and antihydrogen. Nested Penning traps are currently used to confine recombining antihydrogen plasma. Symmetry studies require the production of sufficiently cold antihydrogen. However, plasma drifts within nested Penning traps can increase the kinetic energy of antiprotons that form antihydrogen atoms. Dual levitated coils may serve to confine relatively large, cold, dense non-drifting recombining antihydrogen plasmas. A minimum-B magnetic field that is produced by the coils could provide for atom trapping. A toroidal plasma is confined between the coils. High density plasmas may be possible, by allowing plasma pressure to balance mechanical pressure to keep the coils apart. Progress is reported on theoretical and experimental efforts. The theoretical effort includes the development of a classical trajectory Monte Carlo simulation of confinement. The experimental effort includes levitation of a NdFeB permanent ring magnet, which produces a magnetic field that is qualitatively similar to the field that would be produced by the two coaxial superconducting magnetic coils. Liquid-nitrogen-cooled Bi-2223 high-temperature-superconducting components, with a critical temperature of 108 K, were used to levitate the ring magnet. An issue concerning keeping the plane of the levitated ring horizontal is discussed.

IMPROVED TUBULARS FOR BETTER ECONOMICS IN DEEP GAS WELL DRILLING USING MICROWAVE TECHNOLOGY

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

Dinesh Agrawal; Paul Gigl; Mahlon Dennis

2005-03-01

The main objective of the research program has been to improve the rate-of-penetration in deep hostile environments by improving the life cycle and performance of coiled-tubing, an important component of a deep well drilling system for oil and gas exploration, by utilizing the latest developments in the microwave materials technology. Originally, it was proposed to accomplish this by developing an efficient and economically viable continuous microwave process to sinter continuously formed/extruded steel powder for the manufacture of seamless coiled tubing and other tubular products. However, based on the results and faced with insurmountable difficulties in the extrusion and de-waxing processes,more » the approach of achieving the goals of the program has been slightly changed. In the continuation proposal an approach of microwave sintering combined with Cold Isostatic Press (CIP) and joining (by induction or microwave) is adopted. This process can be developed into a semi-continuous sintering process if the CIP can produce parts fast enough to match the microwave sintering rates. Originally, the entire program was spread over three phases with the following goals: Phase I: Demonstration of the feasibility concept of continuous microwave sintering process for tubular steel products. Phase II: Design, building and testing of a prototype microwave system which shall be combined with a continuous extruder for steel tubular objects. Phase III: Execution of the plan for commercialization of the technology by one of the industrial partners. However, since some of the goals of the phase I were not completed, an extension of nine months was granted and we continued extrusion experiments, designed and built semicontinuous microwave sintering unit.« less

Clinical comparison between a currently available single-loop and an investigational dual-channel endorectal receive coil for prostate magnetic resonance imaging: a feasibility study at 1.5 and 3 T.

PubMed

Vos, Eline K; Sambandamurthy, Sriram; Kamel, Maged; McKenney, Robert; van Uden, Mark J; Hoeks, Caroline M A; Yakar, Derya; Scheenen, Tom W J; Fütterer, Jurgen J

2014-01-01

The objectives of this study were to test the feasibility of an investigational dual-channel next-generation endorectal coil (NG-ERC) in vivo, to quantitatively assess signal-to-noise ratio (SNR), and to get an impression of image quality compared with the current clinically available single-loop endorectal coil (ERC) for prostate magnetic resonance imaging at both 1.5 and 3 T. The study was approved by the institutional review board, and written informed consent was obtained from all patients. In total, 8 consecutive patients with prostate cancer underwent a local staging magnetic resonance examination with the successive use of both coils in 1 session (4 patients at 1.5 T and 4 other patients at 3 T). Quantitative comparison of both coils was performed for the apex, mid-gland and base levels at both field strengths by calculating SNR profiles in the axial plane on an imaginary line in the anteroposterior direction perpendicular to the coil surface. Two radiologists independently assessed the image quality of the T2-weighted and apparent diffusion coefficient maps calculated from diffusion-weighted imaging using a 5-point scale. Improvement of geometric distortion on diffusion-weighted imaging with the use of parallel imaging was explored. Statistical analysis included a paired Wilcoxon signed rank test for SNR and image quality evaluation as well as κ statistics for interobserver agreement. No adverse events were reported. The SNR was higher for the NG-ERC compared with the ERC up to a distance of approximately 40 mm from the surface of the coil at 1.5 T (P < 0.0001 for the apex, the mid-gland, and the base) and approximately 17 mm (P = 0.015 at the apex level) and 30 mm at 3 T (P < 0.0001 for the mid-gland and base). Beyond this distance, the SNR profiles of both coils were comparable. Overall, T2-weighted image quality was considered better for NG-ERC at both field strengths. Quality of apparent diffusion coefficient maps with the use of parallel imaging was rated superior with the NG-ERC at 3 T. The investigational NG-ERC for prostate imaging outperforms the current clinically available ERC in terms of SNR and is feasible for continued development for future use as the next generation endorectal coil for prostate imaging in clinical practice.

ITER CS Model Coil and CS Insert Test Results

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

Martovetsky, N; Michael, P; Minervina, J

2000-09-07

The Inner and Outer modules of the Central Solenoid Model Coil (CSMC) were built by US and Japanese home teams in collaboration with European and Russian teams to demonstrate the feasibility of a superconducting Central Solenoid for ITER and other large tokamak reactors. The CSMC mass is about 120 t, OD is about 3.6 m and the stored energy is 640 MJ at 46 kA and peak field of 13 T. Testing of the CSMC and the CS Insert took place at Japan Atomic Energy Research Institute (JAERI) from mid March until mid August 2000. This paper presents the mainmore » results of the tests performed.« less

Design of Magnetic Shielding and Field Coils for a TES X-Ray Microcalorimeter Test Platform

NASA Technical Reports Server (NTRS)

Miniussi, Antoine R.; Adams, Joseph S.; Bandler, Simon R.; Chervenak, James A.; Datesman, Aaron M.; Doriese, William B.; Eckart, Megan E.; Finkbeiner, Fred M.; Kelley, Richard L.; Kilbourne, Caroline A.;

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

C. Priniski, T. Dodson, M. Duco, S. Raftopoulos, R. Ellis, and A. Brooks

In support of the National Compact Stellerator Experiment (NCSX), stellerator assembly activities continued this past year at the Princeton Plasma Physics Laboratory (PPPL) in partnership with the Oak Ridge National Laboratory (ORNL). The construction program saw the completion of the first two Half Field-Period Assemblies (HPA), each consisting of three modular coils. The full machine includes six such sub-assemblies. A single HPA consists of three of the NCSX modular coils wound and assembled at PPPL. These geometrically-complex threedimensional coils were wound using computer-aided metrology and CAD models to tolerances within +/- 0.5mm. The assembly of these coils required similar accuracymore » on a larger scale with the added complexity of more individual parts and fewer degrees of freedom for correction. Several new potential positioning issues developed for which measurement and control techniques were developed. To accomplish this, CAD coordinate-based computer metrology equipment and software similar to the solutions employed for winding the modular coils was used. Given the size of the assemblies, the primary tools were both interferometeraided and Absolute Distance Measurement (ADM)-only based laser trackers. In addition, portable Coordinate Measurement Machine (CMM) arms and some novel indirect measurement techniques were employed. This paper will detail both the use of CAD coordinate-based metrology technology and the techniques developed and employed for dimensional control of NSCX subassemblies. The results achieved and possible improvements to techniques will be discussed.« less

MR Performance Comparison of a PET/MR System Before and After SiPM-Based Time-of-Flight PET Detector Insertion

NASA Astrophysics Data System (ADS)

Khalighi, Mohammad Mehdi; Delso, Gaspar; Maramraju, Sri Harsha; Deller, Timothy W.; Levin, Craig S.; Glover, Gary H.

2016-10-01

A silicon photomultiplier (SiPM)-based time-of-flight capable PET detector has been integrated with a 70 cm wide-bore 3T MR scanner for simultaneous whole-body imaging (MR750w, GE Healthcare, Waukesha, WI). After insertion of the PET detector, the final PET/MR bore is 60 cm wide (SIGNA PET/MR, GE Healthcare, Waukesha, WI). The MR performance was compared before and after the PET ring insertion. B0 homogeneity, B1+ uniformity of the body coil along with peak B1+, coherent noise, and FBIRN (Function Biomedical Informatics Research Network) tests are used to compare the MR performance. It is shown that B0 homogeneity and coherent noise have not changed according to the system specifications. Peak B1+ is increased by 33% and B1+ inhomogeneity is increased by 4% after PET ring insertion due to a smaller diameter body coil design. The FBIRN test shows similar temporal stability before and after PET ring insertion. Due to a smaller body coil on the PET/MR system, the signal fluctuation to noise ratio (SFNR) and SNR for body receive coil, are improved by 40% and 160% for Echo Planar Imaging (EPI) and spiral sequences respectively. Comparison using RF- and gradient-intensive clinical sequences shows inserting the PET detectors into the wide-bore MRI has not compromised the MR image quality according to these tests.

Improvement of sternal closure stability with reinforced steel wires.

PubMed

McGregor, Walter E; Payne, Maryann; Trumble, Dennis R; Farkas, Kathleen M; Magovern, James A

2003-11-01

Sternal dehiscence occurs when steel wires pull through sternal bone. This study tests the hypothesis that closure stability can be improved by jacketing sternal wires with stainless steel coils, which distribute the force exerted on the bone over a larger area. Midline sternotomies were performed in 6 human cadavers (4 male). Two sternal closure techniques were tested: (1) approximation with six interrupted wires, and (2) the same closure technique reinforced with 3.0-mm-diameter stainless steel coils that jacket wires at the lateral and posterior aspects of the sternum. Intrathoracic pressure was increased with an inflatable rubber bladder placed beneath the anterior chest wall, and sternal separation was measured by means of sonomicrometry crystals. In each trial, intrathoracic pressure was increased until 2.0 mm of motion was detected. Differences in displacement pressures between groups were examined at 0.25-mm intervals using the paired Student's t test. The use of coil-reinforced closures produced significant improvement in sternal stability at all eight displacement levels examined (p < 0.03). Mean pressure required to cause displacement increased 140% (15.5 to 37.3 mm Hg) at 0.25 mm of separation, 103% (34.3 to 69.8 mm Hg) at 1.0 mm of separation, and 122% (46.8 to 103.8 mm Hg) at 2.0 mm of separation. Reinforcement of sternal wires with stainless steel coils substantially improves stability of sternotomy closure in a human cadaver model.

Application Study of a High Temperature Superconducting Fault Current Limiter for Electric Power System

NASA Astrophysics Data System (ADS)

Naito, Yuji; Shimizu, Iwao; Yamaguchi, Iwao; Kaiho, Katsuyuki; Yanabu, Satoru

Using high temperature superconductor, a Superconducting Fault Current Limiter (SFCL) was made and tested. Superconductor and vacuum interrupter as commutation switch are connected in parallel with bypass coil. When a fault occurs and the excessive current flows, superconductor is first quenched and the current is transferred to bypass coil because on voltage drop of superconductor. At the same time, since magnetic field is generated by current which flows in bypass coil, commutation switch is immediately driven by electromagnetic repulsion plate connected to driving rod of vacuum interrupter, and superconductor is separated from this circuit. Using the testing model, we could separate the superconductor from a circuit due to movement of vacuum interrupter within half-cycle current and transfer all current to bypass coil. Since operation of a commutation switch is included in current limiting operation of this testing model, it is one of helpful circuit of development of SFCL in the future. Moreover, since it can make the consumed energy of superconductor small during fault state due to realization of high-speed switch with simple composition, the burden of superconductor is reduced compared with conventional resistive type SFCL and it is considered that the flexibility of a SFCL design increases. Cooperation with a circuit breaker was also considered, the trial calculation of a parameter and energy of operation is conducted and discussion in the case of installing the SFCL to electric power system is made.

Improved Tubulars for Better Economics in Deep Gas Well Drilling Using Microwave Technology

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

Dinesh Agrawal

2006-09-30

The main objective of the entire research program has been to improve the rate-of-penetration in deep hostile environments by improving the life cycle and performance of coiled-tubing, an important component of a deep well drilling system for oil and gas exploration, by utilizing the latest developments in the microwave materials technology. Based on the results of the Phase I and insurmountable difficulties faced in the extrusion and de-waxing processes, the approach of achieving the goals of the program was slightly changed in the Phase II in which an approach of microwave sintering combined with Cold Isostatic Press (CIP) and joiningmore » (by induction or microwave) has been adopted. This process can be developed into a semicontinuous sintering process if the CIP can produce parts fast enough to match the microwave sintering rates. The main objective of the Phase II research program is to demonstrate the potential to economically manufacture microwave processed coiled tubing with improved performance for extended useful life under hostile coiled tubing drilling conditions. After the completion of the Phase II, it is concluded that scale up and sintering of a thin wall common O.D. size tubing that is widely used in the market is still to be proved and further experimentation and refinement of the sintering process is needed in Phase III. Actual manufacturing capability of microwave sintered, industrial quality, full length tubing will most likely require several million dollars of investment.« less

Improved Tubulars for Better Economics in Deep Gas Well Drilling using Microwave Technology

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

Dinesh Agrawal; Paul Gigl; Mark Hunt

2007-07-31

The main objective of the entire research program has been to improve the rate-of-penetration in deep hostile environments by improving the life cycle and performance of coiled-tubing, an important component of a deep well drilling system for oil and gas exploration, by utilizing the latest developments in the microwave materials technology. Based on the results of the Phase I and insurmountable difficulties faced in the extrusion and de-waxing processes, the approach of achieving the goals of the program was slightly changed in the Phase II in which an approach of microwave sintering combined with Cold Isostatic Press (CIP) and joiningmore » (by induction or microwave) has been adopted. This process can be developed into a semicontinuous sintering process if the CIP can produce parts fast enough to match the microwave sintering rates. The main objective of the Phase II research program is to demonstrate the potential to economically manufacture microwave processed coiled tubing with improved performance for extended useful life under hostile coiled tubing drilling conditions. After the completion of the Phase II, it is concluded that scale up and sintering of a thin wall common O.D. size tubing that is widely used in the market is still to be proved and further experimentation and refinement of the sintering process is needed in Phase III. Actual manufacturing capability of microwave sintered, industrial quality, full length tubing will most likely require several million dollars of investment.« less

Characterizing superconducting thin films using AC Magnetic Susceptibility

NASA Astrophysics Data System (ADS)

Mahoney, C. H.; Porzio, J.; Sullivan, M. C.

2014-03-01

We present our work on using ac magnetic susceptibility to determine the critical temperature of superconducting thin films. In ac magnetic susceptibility, the thin film is placed between two coils. One coil carries an ac signal, creating a varying external magnetic field. We measure the voltage induced in the pick-up coil on the opposite side of the sample and measure how the sample magnetization changes as the temperature changes. We will present our work to use ac susceptibility to determine critical temperature and superconducting volume fraction. Using our own analysis program, we are able to accurately locate the critical temperatures of the samples and determine the transition width. For the superconducting volume fraction, we etch samples in order to control the thicknesses of the sample and measure how much of the material grown on the surface is superconducting. Supported by NFS grant DMR-1305637.

Design, manufacturing and tests of first cryogen-free MgB2 prototype coils for offshore wind generators

NASA Astrophysics Data System (ADS)

Sarmiento, G.; Sanz, S.; Pujana, A.; Merino, J. M.; Iturbe, R.; Apiñaniz, S.; Nardelli, D.; Marino, I.

2014-05-01

Although renewable sector has started to take advantage of the offshore wind energy recently, the development is very intense. Turbines reliability, size, and cost are key aspects for the wind industry, especially in marine locations. A superconducting generator will allow a significant reduction in terms of weight and size, but cost and reliability are two aspects to deal with. MgB2 wire is presented as one promising option to be used in superconducting coils for wind generators. This work shows the experimental results in first cryogen-free MgB2 prototype coils, designed according to specific requirements of TECNALIA's wind generator concept.

Corrosion Detection in Airframes Using a New Flux-Focusing Eddy Current Probe

NASA Technical Reports Server (NTRS)

Fulton, James P.; Wincheski, Buzz; Nath, Shridhar; Namkung, Min

1994-01-01

A new flux-focusing eddy current probe was recently developed at NASA Langley Research Center. The new probe is similar in design to a reflection type eddy current probe, but is unique in that it does not require the use of an impedance bridge for balancing. The device monitors the RMS output voltage of a pickup coil and, as a result, is easier to operate and interpret than traditional eddy current instruments. The unique design feature of the probe is a ferromagnetic cylinder, typically 1020 steel, which separates a concentrically positioned drive and pickup coil. The increased permeability of the steel causes the magnetic flux produced by the drive coil to be focused in a ring around the pickup coil. At high frequencies the eddy currents induced in both the sample and the cylinder allow little or no flux to link with the pickup coil. This results in a self-nulling condition which has been shown to be useful for the unambiguous detection of cracks in conducting materials. As the frequency is lowered the flux produced by the drive coil begins to link with the pickup coil causing an output which, among other things, is proportional to the thickness of the test specimen. This enables highly accurate measurements of the thickness of conducting materials and helps to facilitate the monitoring of thickness variations in a conducting structure such as an aircraft fuselage. Under ideal laboratory conditions the probe can sense thickness changes on the order of 1% as illustrated. However, this is highly dependent upon the thickness, and the geometric complexity of the sample being tested and for practical problems the sensitivity is usually much less. In this presentation we highlight some of the advantages and limitations in using the probe to inspect aircraft panels for corrosion and other types of material nonuniformities. In particular, we present preliminary results which illustrate the probes capabilities for detecting first and second layer corrosion in aircraft panels which may contain air gaps between the layers. Since the probe utilized eddy currents its corrosion detection capabilities are similar to convectional eddy current techniques, but the new probe is much easier to use.

Effect of Dimension and Shape of Magnet on the Performance AC Generator with Translation Motion

NASA Astrophysics Data System (ADS)

Indriani, A.; Dimas, S.; Hendra

2018-02-01

The development of power plants using the renewable energy sources is very rapid. Renewable energy sources used solar energy, wind energy, ocean wave energy and other energy. All of these renewable energy sources require a processing device or a change of motion system to become electrical energy. One processing device is a generator which have work principle of converting motion (mechanical) energy into electrical energy with rotary shaft, blade and other motion components. Generator consists of several types of rotation motion and linear motion (translational). The generator have components such as rotor, stator and anchor. In the rotor and stator having magnet and winding coil as an electric generating part of the electric motion force. Working principle of AC generator with linear motion (translation) also apply the principle of Faraday that is using magnetic induction which change iron magnet to produce magnetic flux. Magnetic flux is captured by the stator to be converted into electrical energy. Linear motion generators consist of linear induction machine, wound synchronous machine field, and permanent magnet synchronous [1]. Performance of synchronous generator of translation motion is influenced by magnet type, magnetic shape, coil winding, magnetic and coil spacing and others. In this paper focus on the neodymium magnet with varying shapes, number of coil windings and gap of magnetic distances. This generator work by using pneumatic mechanism (PLTGL) for power plants system. Result testing of performance AC generator translation motion obtained that maximum voltage, current and power are 63 Volt for diameter winding coil 0.15 mm, number of winding coil 13000 and distance of magnet 20 mm. For effect shape of magnet, maximum voltage happen on rectangle magnet 30x20x5 mm with 4.64 Volt. Voltage and power on effect of diameter winding coil is 14.63 V and 17.82 W at the diameter winding coil 0.7 and number of winding coil is 1260 with the distance of magnet 25 mm.

Development of a Rigid One-Meter-Side and Cooled Coil Sensor at 77 K for Magnetic Resonance Sounding to Detect Subsurface Water Sources.

PubMed

Lin, Jun; Du, Guanfeng; Zhang, Jian; Yi, Xiaofeng; Jiang, Chuandong; Lin, Tingting

2017-06-12

Magnetic resonance sounding (MRS) using the Earth's magnetic field is a noninvasive and on-site geophysical technique providing quantitative characteristics of aquifers in the subsurface. When the MRS technology is applied in a mine or tunnel for advance detecting the source of water that may cause disastrous accident, spatial constraints limit the size of coil sensor and thus lower the detection capability. In this paper, a coil sensor for detecting the weak MRS signal is designed and the signal to noise (SNR) for the coil sensor is analyzed and optimized. The coil sensor has a rigid structure and square size of 1 m for deploying in a narrow underground space and is cooled at a low temperature of 77 K for improving the SNR. A theoretical calculation and an experimental test in an electromagnetically shielded room (EMSR) show that the optimal design of coil sensor consists of an 80-turn coil and a low-current-noise preamplifier AD745. It has a field sensitivity of 0.17 fT / Hz in the EMSR at 77 K, which is superior to the low temperature Superconducting Quantum Interference Device (LT SQUID) that is the latest application in MRS and the cooled coil with a diameter of 9 cm when detecting the laboratory NMR signal in kHz range. In the field experiment above the Taipingchi Reservoir near Changchun in China, the cooled coil sensor (CCS) developed in this paper has successfully obtained a valid weak MRS signal in high noise environment. The field results showed that the quality of measured MRS signal at 77 K is significantly superior to that at 298 K and the SNR is improved up to three times. This property of CCS makes the MRS instrument more convenient and reliable in a constricted space underground engineering environment (e.g., a mine or a tunnel).

Using a whole-body 31P birdcage transmit coil and 16-element receive array for human cardiac metabolic imaging at 7T

PubMed Central

Dragonu, Iulius; Almujayyaz, Salam; Batzakis, Alex; Young, Liam A. J.; Purvis, Lucian A. B.; Clarke, William T.; Wichmann, Tobias; Lanz, Titus; Neubauer, Stefan; Robson, Matthew D.; Klomp, Dennis W. J.; Rodgers, Christopher T.

2017-01-01

Purpose Cardiac phosphorus magnetic resonance spectroscopy (31P-MRS) provides unique insight into the mechanisms of heart failure. Yet, clinical applications have been hindered by the restricted sensitivity of the surface radiofrequency-coils normally used. These permit the analysis of spectra only from the interventricular septum, or large volumes of myocardium, which may not be meaningful in focal disease. Löring et al. recently presented a prototype whole-body (52 cm diameter) transmit/receive birdcage coil for 31P at 7T. We now present a new, easily-removable, whole-body 31P transmit radiofrequency-coil built into a patient-bed extension combined with a 16-element receive array for cardiac 31P-MRS. Materials and methods A fully-removable (55 cm diameter) birdcage transmit coil was combined with a 16-element receive array on a Magnetom 7T scanner (Siemens, Germany). Electro-magnetic field simulations and phantom tests of the setup were performed. In vivo maps of B1+, metabolite signals, and saturation-band efficiency were acquired across the torsos of eight volunteers. Results The combined (volume-transmit, local receive array) setup increased signal-to-noise ratio 2.6-fold 10 cm below the array (depth of the interventricular septum) compared to using the birdcage coil in transceiver mode. The simulated coefficient of variation for B1+ of the whole-body coil across the heart was 46.7% (surface coil 129.0%); and the in vivo measured value was 38.4%. Metabolite images of 2,3-diphosphoglycerate clearly resolved the ventricular blood pools, and muscle tissue was visible in phosphocreatine (PCr) maps. Amplitude-modulated saturation bands achieved 71±4% suppression of phosphocreatine PCr in chest-wall muscles. Subjects reported they were comfortable. Conclusion This easy-to-assemble, volume-transmit, local receive array coil combination significantly improves the homogeneity and field-of-view for metabolic imaging of the human heart at 7T. PMID:29073228

Development of a Rigid One-Meter-Side and Cooled Coil Sensor at 77 K for Magnetic Resonance Sounding to Detect Subsurface Water Sources

PubMed Central

Lin, Jun; Du, Guanfeng; Zhang, Jian; Yi, Xiaofeng; Jiang, Chuandong; Lin, Tingting

2017-01-01

Magnetic resonance sounding (MRS) using the Earth’s magnetic field is a noninvasive and on-site geophysical technique providing quantitative characteristics of aquifers in the subsurface. When the MRS technology is applied in a mine or tunnel for advance detecting the source of water that may cause disastrous accident, spatial constraints limit the size of coil sensor and thus lower the detection capability. In this paper, a coil sensor for detecting the weak MRS signal is designed and the signal to noise (SNR) for the coil sensor is analyzed and optimized. The coil sensor has a rigid structure and square size of 1 m for deploying in a narrow underground space and is cooled at a low temperature of 77 K for improving the SNR. A theoretical calculation and an experimental test in an electromagnetically shielded room (EMSR) show that the optimal design of coil sensor consists of an 80-turn coil and a low-current-noise preamplifier AD745. It has a field sensitivity of 0.17 fT/Hz in the EMSR at 77 K, which is superior to the low temperature Superconducting Quantum Interference Device (LT SQUID) that is the latest application in MRS and the cooled coil with a diameter of 9 cm when detecting the laboratory NMR signal in kHz range. In the field experiment above the Taipingchi Reservoir near Changchun in China, the cooled coil sensor (CCS) developed in this paper has successfully obtained a valid weak MRS signal in high noise environment. The field results showed that the quality of measured MRS signal at 77 K is significantly superior to that at 298 K and the SNR is improved up to three times. This property of CCS makes the MRS instrument more convenient and reliable in a constricted space underground engineering environment (e.g., a mine or a tunnel). PMID:28604621

Aspirin and Clopidogrel Inhibit Aneurysm Healing after HydroCoil Implantation in External Carotid Artery Aneurysm Model.

PubMed

Zhang, Chao; Li, Peiliang; Xi, Guohua; Gemmete, Joseph J; Chaudhary, Neeraj; Thompson, B Gregory; Pandey, Aditya S

2016-11-01

To understand whether the use of antiplatelet agents leads to less intra-aneurismal tissue formation following coil implantation in a rat end-pouch external carotid artery (ECA) aneurysm model. End-pouch ECA aneurysms were created in adult rats and were then embedded with either platinum or HydroCoils. Rats were treated either with aspirin, clopidogrel, aspirin + clopidogrel, or saline for 2 weeks after coil implantation. At 2 weeks after coil implantation, rats were sacrificed and the aneurysm pouch was removed for histological and immunohistochemical analysis. A blinded single observer calculated the percentage of the organized area and the residual length of elastic lamina within the aneurysm. Student's t-test was used to compare data from image analysis between the different groups. Within the platinum group, the organized tissue area was not affected by antiplatelet administration (aspirin versus saline, P = .83; clopidogrel versus saline, P = .46; aspirin + clopidogrel versus saline, P = .54). For the HydroCoil group, the organized tissue area was significantly reduced (aspirin versus saline, P = .02; clopidogrel versus saline, P = .04; aspirin + clopidogrel versus saline, P = .02) in rats treated with antiplatelet agents; however, no difference (aspirin versus clopidogrel, P = .8; aspirin versus aspirin + clopidogrel, P = .3; clopidogrel versus aspirin + clopidogrel, P = .5) was found among type or combination of antiplatelets administered. HydroCoil-treated aneurysms had a similar number of macrophages compared to the platinum group (P = .3819); however, the HydroCoil group had significant suppression of macrophages in the groups treated with combined antiplatelets (P = .02). Following HydroCoil implantation, the area of organized tissue is diminished significantly in a rat end-pouch ECA aneurysm model treated with antiplatelets. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.

Direct Fuel Injector Power Drive System Optimization

DTIC Science & Technology

2014-04-01

solenoid coil to create magnetic field in the stator. Then, the stator pulls the pintle to open the injector nozzle . This pintle movement occurs when the...that typically deal with power strategies to the injector solenoid coil. Numerical simulation codes for diesel injection systems were developed by...Laboratory) for providing the JP-8 test fuel. REFERENCES 1. Digesu, P. and Laforgia D., “ Diesel electro- injector : A numerical simulation code”. Journal of

Optically controlled switch-mode current-source amplifiers for on-coil implementation in high field parallel transmission

PubMed Central

Gudino, Natalia; Duan, Qi; de Zwart, Jacco A; Murphy-Boesch, Joe; Dodd, Stephen J; Merkle, Hellmut; van Gelderen, Peter; Duyn, Jeff H

2015-01-01

Purpose We tested the feasibility of implementing parallel transmission (pTX) for high field MRI using a radiofrequency (RF) amplifier design to be located on or in the immediate vicinity of a RF transmit coil. Method We designed a current-source switch-mode amplifier based on miniaturized, non-magnetic electronics. Optical RF carrier and envelope signals to control the amplifier were derived, through a custom-built interface, from the RF source accessible in the scanner control. Amplifier performance was tested by benchtop measurements as well as with imaging at 7 T (300 MHz) and 11.7 T (500 MHz). The ability to perform pTX was evaluated by measuring inter-channel coupling and phase adjustment in a 2-channel setup. Results The amplifier delivered in excess of 44 W RF power and caused minimal interference with MRI. The interface derived accurate optical control signals with carrier frequencies ranging from 64 to 750 MHz. Decoupling better than 14 dB was obtained between 2 coil loops separated by only 1 cm. Application to MRI was demonstrated by acquiring artifact-free images at 7 T and 11.7 T. Conclusion An optically controlled miniaturized RF amplifier for on-coil implementation at high field is demonstrated that should facilitate implementation of high-density pTX arrays. PMID:26256671

Design and Fabrication of a Miniaturized GMI Magnetic Sensor Based on Amorphous Wire by MEMS Technology

PubMed Central

Chen, Jiawen; Li, Jianhua; Li, Yiyuan; Chen, Yulong

2018-01-01

A miniaturized Co-based amorphous wire GMI (Giant magneto-impedance) magnetic sensor was designed and fabricated in this paper. The Co-based amorphous wire was used as the sense element due to its high sensitivity to the magnetic field. A three-dimensional micro coil surrounding the Co-based amorphous wire was fabricated by MEMS (Micro-Electro-Mechanical System) technology, which was used to extract the electrical signal. The three-dimensional micro pick-up coil was designed and simulated with HFSS (High Frequency Structure Simulator) software to determine the key parameters. Surface micro machining MEMS (Micro-Electro-Mechanical System) technology was employed to fabricate the three-dimensional coil. The size of the developed amorphous wire magnetic sensor is 5.6 × 1.5 × 1.1 mm3. Helmholtz coil was used to characterize the performance of the device. The test results of the sensor sample show that the voltage change is 130 mV/Oe and the linearity error is 4.83% in the range of 0~45,000 nT. The results indicate that the developed miniaturized magnetic sensor has high sensitivity. By testing the electrical resistance of the samples, the results also showed high uniformity of each device. PMID:29494477

Fabrication and Optimal Design of Biodegradable Polymeric Stents for Aneurysms Treatments

PubMed Central

Han, Xue; Wu, Xia; Kelly, Michael; Chen, Xiongbiao

2017-01-01

An aneurysm is a balloon-like bulge in the wall of blood vessels, occurring in major arteries of the heart and brain. Biodegradable polymeric stent-assisted coiling is expected to be the ideal treatment of wide-neck complex aneurysms. This paper presents the development of methods to fabricate and optimally design biodegradable polymeric stents for aneurysms treatment. Firstly, a dispensing-based rapid prototyping (DBRP) system was developed to fabricate coil and zigzag structures of biodegradable polymeric stents. Then, compression testing was carried out to characterize the radial deformation of the stents fabricated with the coil or zigzag structure. The results illustrated the stent with a zigzag structure has a stronger radial stiffness than the one with a coil structure. On this basis, the stent with a zigzag structure was chosen for the development of a finite element model for simulating the real compression tests. The result showed the finite element model of biodegradable polymeric stents is acceptable within a range of radial deformation around 20%. Furthermore, the optimization of the zigzag structure was performed with ANSYS DesignXplorer, and the results indicated that the total deformation could be decreased by 35.7% by optimizing the structure parameters, which would represent a significant advance of the radial stiffness of biodegradable polymeric stents. PMID:28264515

In-vivo force decay of nickel-titanium closed-coil springs.

PubMed

Cox, Crystal; Nguyen, Tung; Koroluk, Lorne; Ko, Ching-Chang

2014-04-01

Nickel-titanium closed-coil springs are purported to deliver constant forces over extended ranges of activation and working times. In-vivo studies supporting this claim are limited. The objective of this study was to evaluate changes in force-decay properties of nickel-titanium closed-coil springs after clinical use. Pseudoelastic force-deflection curves for 30 nickel-titanium coil springs (used intraorally) and 15 matched laboratory control springs (simulated intraoral conditions: artificial saliva, 37°C) were tested before and after retrieval via dynamic mechanical analysis and a testing machine, respectively, to evaluate the amounts of force-loss and hysteresis change after 4, 8, or 12 weeks of working time (n = 10 per group). The effects of the oral environment and clinical use on force properties were evaluated by comparing in-vivo and in-vitro data. The springs studied showed a statistically significant decrease in force (approximately 12%) after 4 weeks of clinical use (P <0.01), with a further significant decrease (approximately 7%) from 4 to 8 weeks (P = 0.03), and force levels appearing to remain steady thereafter. Clinical space closure at an average rate of 0.91 mm per month was still observed despite this decrease in force. In-vivo and in-vitro force-loss data were not statistically different. Nickel-titanium closed-coil springs do not deliver constant forces when used intraorally, but they still allow for space-closure rates of approximately 1 mm per month. Copyright © 2014 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.

Theoretical and Experimental Estimations of Volumetric Inductive Phase Shift in Breast Cancer Tissue

NASA Astrophysics Data System (ADS)

González, C. A.; Lozano, L. M.; Uscanga, M. C.; Silva, J. G.; Polo, S. M.

2013-04-01

Impedance measurements based on magnetic induction for breast cancer detection has been proposed in some studies. This study evaluates theoretical and experimentally the use of a non-invasive technique based on magnetic induction for detection of patho-physiological conditions in breast cancer tissue associated to its volumetric electrical conductivity changes through inductive phase shift measurements. An induction coils-breast 3D pixel model was designed and tested. The model involves two circular coils coaxially centered and a human breast volume centrally placed with respect to the coils. A time-harmonic numerical simulation study addressed the effects of frequency-dependent electrical properties of tumoral tissue on the volumetric inductive phase shift of the breast model measured with the circular coils as inductor and sensor elements. Experimentally; five female volunteer patients with infiltrating ductal carcinoma previously diagnosed by the radiology and oncology departments of the Specialty Clinic for Women of the Mexican Army were measured by an experimental inductive spectrometer and the use of an ergonomic inductor-sensor coil designed to estimate the volumetric inductive phase shift in human breast tissue. Theoretical and experimental inductive phase shift estimations were developed at four frequencies: 0.01, 0.1, 1 and 10 MHz. The theoretical estimations were qualitatively in agreement with the experimental findings. Important increments in volumetric inductive phase shift measurements were evident at 0.01MHz in theoretical and experimental observations. The results suggest that the tested technique has the potential to detect pathological conditions in breast tissue associated to cancer by non-invasive monitoring. Further complementary studies are warranted to confirm the observations.

Direct Digital Control Study.

DTIC Science & Technology

1985-02-01

Deck - Cold Deck Reset Reheat Coil Reset Steam Boiler Optimization [lot Water Outside Air Reset Chiller Optimization Chiller Water Temperature Reset...with programming techniques for each type of installed DDC in order to effect changes in operating setpoints and application programs. *Communication...can be changed without recailbration of instrumentation devices. Changes to the application software, operating setpoints and parameters require the

Destruction of the Last Good Magnetic Surface in Diii-D Usn with Elms and C-Coils Shot 115467 due to C-Coils Using Maps

NASA Astrophysics Data System (ADS)

McCray, A.; Punjabi, A.; Ali, H.

2004-11-01

Unperturbed magnetic topology of DIII-D shot 115467 is described by the symmetric simple map (SSM) with map parameter k=0.2623 [1], then last good surface passes through x=0 and y=0.9995, q_edge=6.48 (same as in shot 115467) if six iterations of SSM are taken to be equivalent to single toroidal circuit of DIII-D. The dipole map (DM) calculates the effects of localized, external high mode numbers magnetic perturbations on motion of field lines. We use dipole map to describe effects of C-coils on field line trajectories in DIII-D. We apply DM after each iteration of SSM, with s=1.0021, x_dipole=1.5617, y_dipole= 0 [1] for shot 115467. We study the changes in the last good surface and its destruction as a function of I_C-coil. This work is supported by NASA SHARP program and DE-FG02-02ER54673. [1] H. Ali, A. Punjabi, A. Boozer, and T. Evans, presented at the 31st European Physical Society Plasma Physics Meeting, London, UK, June 29, 2004, paper P2-172.

Equations for nickel-chromium wire heaters of column transfer lines in gas chromatographic-electroantennographic detection (GC-EAD).

PubMed

Byers, John A

2004-05-30

Heating of chromatographic columns, transfer lines, and other devices is often required in neuroscience research. For example, volatile compounds passing through a capillary column of a gas chromatograph (GC) can be split, with half exiting the instrument through a heated transfer line to an insect antenna or olfactory sensillum for electroantennographic detector (GC-EAD) recordings. The heated transfer line is used to prevent condensation of various chemicals in the capillary that would otherwise occur at room temperature. Construction of such a transfer line heater is described using (80/20%) nickel-chromium heating wire wrapped in a helical coil and powered by a 120/220 V ac rheostat. Algorithms were developed in a computer program to estimate the voltage at which a rheostat should be set to obtain the desired heater temperature for a specific coil. The coil attributes (radius, width, number of loops, or length of each loop) are input by the user, as well as AWG size of heating wire and desired heater temperature. The program calculates total length of wire in the helix, resistance of the wire, amperage used, and the voltage to set the rheostat. A discussion of semiochemical isolation methods using the GC-EAD and bioassays is presented.

Performance of the first short model 150 mm aperture Nb$$_3$$Sn Quadrupole MQXFS for the High- Luminosity LHC upgrade

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

Chlachidze, G.; et al.

2016-08-30

The US LHC Accelerator Research Program (LARP) and CERN combined their efforts in developing Nb3Sn magnets for the High-Luminosity LHC upgrade. The ultimate goal of this collaboration is to fabricate large aperture Nb3Sn quadrupoles for the LHC interaction regions (IR). These magnets will replace the present 70 mm aperture NbTi quadrupole triplets for expected increase of the LHC peak luminosity by a factor of 5. Over the past decade LARP successfully fabricated and tested short and long models of 90 mm and 120 mm aperture Nb3Sn quadrupoles. Recently the first short model of 150 mm diameter quadrupole MQXFS was builtmore » with coils fabricated both by the LARP and CERN. The magnet performance was tested at Fermilab’s vertical magnet test facility. This paper reports the test results, including the quench training at 1.9 K, ramp rate and temperature dependence studies.« less

Rugged, portable tungsten coil atomic emission spectrometer.

PubMed

Gu, Jiyan; Oliveira, Silvana R; Donati, George L; Gomes Neto, José Anchieta; Jones, Bradley T

2011-04-01

Tungsten coil atomic emission spectrometry is an ideal technique for field applications because of its simplicity, low cost, low power requirement, and independence from cooling systems. A new, portable, compact design is reported here. The tungsten coil is extracted from an inexpensive 24 V, 250 W commercial light bulb. The coil is housed in a small, aluminum cell. The emission signal exits from a small aperture in the cell, while the bulk of the blackbody emission from the tungsten coil is blocked. The resulting spectra exhibit extremely low background signals. The atomization cell, a single lens, and a hand-held charge coupled device (CCD) spectrometer are fixed on a 1 × 6 × 30 cm ceramic base. The resulting system is robust and easily transported. A programmable, miniature 400 W solid-state constant current power supply controls the temperature of the coil. Fifteen elements are determined with the system (Ba, Cs, Li, Rb, Cr, Sr, Eu, Yb, Mn, Fe, Cu, Mg, V, Al, and Ga). The precision ranges from 4.3% to 8.4% relative standard deviation for repetitive measurements of the same solution. Detection limits are in the 0.04 to 1500 μg/L range. Accuracy is tested using standard reference materials for polluted water, peach leaves, and tomato leaves. For those elements present above the detection limit, recoveries range from 72% to 147%.

MR-compatibility assessment of MADPET4: a study of interferences between an SiPM-based PET insert and a 7 T MRI system.

PubMed

Omidvari, Negar; Topping, Geoffrey; Cabello, Jorge; Paul, Stephan; Schwaiger, Markus; Ziegler, Sibylle I

2018-05-01

Compromises in the design of a positron emission tomography (PET) insert for a magnetic resonance imaging (MRI) system should minimize the deterioration of image quality in both modalities, particularly when simultaneous demanding acquisitions are performed. In this work, the advantages of using individually read-out crystals with high-gain silicon photomultipliers (SiPMs) were studied with a small animal PET insert for a 7 T MRI system, in which the SiPM charge was transferred to outside the MRI scanner using coaxial cables. The interferences between the two systems were studied with three radio-frequency (RF) coil configurations. The effects of PET on the static magnetic field, flip angle distribution, RF noise, and image quality of various MRI sequences (gradient echo, spin echo, and echo planar imaging (EPI) at 1 H frequency, and chemical shift imaging at 13 C frequency) were investigated. The effects of fast-switching gradient fields and RF pulses on PET count rate were studied, while the PET insert and the readout electronics were not shielded. Operating the insert inside a 1 H volume coil, used for RF transmission and reception, limited the MRI to T1-weighted imaging, due to coil detuning and RF attenuation, and resulted in significant PET count loss. Using a surface receive coil allowed all tested MR sequences to be used with the insert, with 45-59% signal-to-noise ratio (SNR) degradation, compared to without PET. With a 1 H/ 13 C volume coil inside the insert and shielded by a copper tube, the SNR degradation was limited to 23-30% with all tested sequences. The insert did not introduce any discernible distortions into images of two tested EPI sequences. Use of truncated sinc shaped RF excitation pulses and gradient field switching had negligible effects on PET count rate. However, PET count rate was substantially affected by high-power RF block pulses and temperature variations due to high gradient duty cycles.

High-Purity Aluminum Magnet Technology for Advanced Space Transportation Systems

NASA Technical Reports Server (NTRS)

Goodrich, R. G.; Pullam, B.; Rickle, D.; Litchford, R. J.; Robertson, G. A.; Schmidt, D. D.; Cole, John (Technical Monitor)

2001-01-01

Basic research on advanced plasma-based propulsion systems is routinely focused on plasmadynamics, performance, and efficiency aspects while relegating the development of critical enabling technologies, such as flight-weight magnets, to follow-on development work. Unfortunately, the low technology readiness levels (TRLs) associated with critical enabling technologies tend to be perceived as an indicator of high technical risk, and this, in turn, hampers the acceptance of advanced system architectures for flight development. Consequently, there is growing recognition that applied research on the critical enabling technologies needs to be conducted hand in hand with basic research activities. The development of flight-weight magnet technology, for example, is one area of applied research having broad crosscutting applications to a number of advanced propulsion system architectures. Therefore, NASA Marshall Space Flight Center, Louisiana State University (LSU), and the National High Magnetic Field Laboratory (NHMFL) have initiated an applied research project aimed at advancing the TRL of flight-weight magnets. This Technical Publication reports on the group's initial effort to demonstrate the feasibility of cryogenic high-purity aluminum magnet technology and describes the design, construction, and testing of a 6-in-diameter by 12-in-long aluminum solenoid magnet. The coil was constructed in the machine shop of the Department of Physics and Astronomy at LSU and testing was conducted in NHMFL facilities at Florida State University and at Los Alamos National Laboratory. The solenoid magnet was first wound, reinforced, potted in high thermal conductivity epoxy, and bench tested in the LSU laboratories. A cryogenic container for operation at 77 K was also constructed and mated to the solenoid. The coil was then taken to NHMFL facilities in Tallahassee, FL. where its magnetoresistance was measured in a 77 K environment under steady magnetic fields as high as 10 T. In addition, the temperature dependence of the coil's resistance was measured from 77 to 300 K. Following this series of tests, the coil was transported to NHMFL facilities in Los Alamos, NM, and pulsed to 2 T using an existing capacitor bank pulse generator. The coil was completely successful in producing the desired field without damage to the windings.

Dual resonant frequencies effects on an induction-based oil palm fruit sensor.

PubMed

Harun, Noor Hasmiza; Misron, Norhisam; Mohd Sidek, Roslina; Aris, Ishak; Wakiwaka, Hiroyuki; Tashiro, Kunihisa

2014-11-19

As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller to harvest a good oil palm Fresh Fruit Bunch (FFB). Conventionally, the main reference used by Malaysian harvesters is the manual grading standard published by the Malaysian Palm Oil Board (MPOB). A good oil palm FFB consists of all matured fruitlets, aged between 18 to 21 weeks of antheses (WAA). To expedite the harvesting process, it is crucial to implement an automated detection system for determining the maturity of the oil palm FFB. Various automated detection methods have been proposed by researchers in the field to replace the conventional method. In our preliminary study, a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunch was proposed. The design of the proposed air coil sensor based on the inductive sensor was further investigated mainly in the context of the effect of coil diameter to improve its sensitivity. In this paper, the sensitivity of the inductive sensor was further examined with a dual flat-type shape of air coil. The dual air coils were tested on fifteen samples of fruitlet from two categories, namely ripe and unripe. Samples were tested within 20 Hz to 10 MHz while evaluations on both peaks were done separately before the gap between peaks was analyzed. A comparative analysis was conducted to investigate the improvement in sensitivity of the induction-based oil palm fruit sensor as compared to previous works. Results from the comparative study proved that the inductive sensor using a dual flat-type shape air coil has improved by up to 167%. This provides an indication in the improvement in the coil sensitivity of the palm oil fruit sensor based on the induction concept.

Dual Resonant Frequencies Effects on an Induction-Based Oil Palm Fruit Sensor

PubMed Central

Harun, Noor Hasmiza; Misron, Norhisam; Sidek, Roslina Mohd; Aris, Ishak; Wakiwaka, Hiroyuki; Tashiro, Kunihisa

2014-01-01

As the main exporter in the oil palm industry, the need to improve the quality of palm oil has become the main interest among all the palm oil millers in Malaysia. To produce good quality palm oil, it is important for the miller to harvest a good oil palm Fresh Fruit Bunch (FFB). Conventionally, the main reference used by Malaysian harvesters is the manual grading standard published by the Malaysian Palm Oil Board (MPOB). A good oil palm FFB consists of all matured fruitlets, aged between 18 to 21 weeks of antheses (WAA). To expedite the harvesting process, it is crucial to implement an automated detection system for determining the maturity of the oil palm FFB. Various automated detection methods have been proposed by researchers in the field to replace the conventional method. In our preliminary study, a novel oil palm fruit sensor to detect the maturity of oil palm fruit bunch was proposed. The design of the proposed air coil sensor based on the inductive sensor was further investigated mainly in the context of the effect of coil diameter to improve its sensitivity. In this paper, the sensitivity of the inductive sensor was further examined with a dual flat-type shape of air coil. The dual air coils were tested on fifteen samples of fruitlet from two categories, namely ripe and unripe. Samples were tested within 20 Hz to 10 MHz while evaluations on both peaks were done separately before the gap between peaks was analyzed. A comparative analysis was conducted to investigate the improvement in sensitivity of the induction-based oil palm fruit sensor as compared to previous works. Results from the comparative study proved that the inductive sensor using a dual flat-type shape air coil has improved by up to 167%. This provides an indication in the improvement in the coil sensitivity of the palm oil fruit sensor based on the induction concept. PMID:25414970

Genome-Wide Identification of Arabidopsis Coiled-Coil Proteins and Establishment of the ARABI-COIL Database1

PubMed Central

Rose, Annkatrin; Manikantan, Sankaraganesh; Schraegle, Shannon J.; Maloy, Michael A.; Stahlberg, Eric A.; Meier, Iris

2004-01-01

Increasing evidence demonstrates the importance of long coiled-coil proteins for the spatial organization of cellular processes. Although several protein classes with long coiled-coil domains have been studied in animals and yeast, our knowledge about plant long coiled-coil proteins is very limited. The repeat nature of the coiled-coil sequence motif often prevents the simple identification of homologs of animal coiled-coil proteins by generic sequence similarity searches. As a consequence, counterparts of many animal proteins with long coiled-coil domains, like lamins, golgins, or microtubule organization center components, have not been identified yet in plants. Here, all Arabidopsis proteins predicted to contain long stretches of coiled-coil domains were identified by applying the algorithm MultiCoil to a genome-wide screen. A searchable protein database, ARABI-COIL (http://www.coiled-coil.org/arabidopsis), was established that integrates information on number, size, and position of predicted coiled-coil domains with subcellular localization signals, transmembrane domains, and available functional annotations. ARABI-COIL serves as a tool to sort and browse Arabidopsis long coiled-coil proteins to facilitate the identification and selection of candidate proteins of potential interest for specific research areas. Using the database, candidate proteins were identified for Arabidopsis membrane-bound, nuclear, and organellar long coiled-coil proteins. PMID:15020757

Influence of roll levelling on material properties and postforming springback

NASA Astrophysics Data System (ADS)

Galdos, Lander; Mendiguren, Joseba; de Argandoña, Eneko Saenz; Otegi, Nagore; Silvestre, Elena

2018-05-01

Roll levelling is commonly used in cut to length and blanking lines to flatten initial coils and produce residual stress free precuts. Roll straightener is also used to remove coil-set when progressive dies are used and the starting raw material is a coil. Industrial evidences have proved that roll leveler or straightener tuning is crucial to get a robust process and to obtain repetitive springback values after stamping. This is more relevant when using Advanced High Strength Steels and aluminum coils. However, the mechanisms affecting this material behavior are unknown and how the levelling technology affects the material properties has not been yet reported. In this paper, the influence the roll levelling process has on the final properties of a 6xxx aluminum alloy is studied. For that, as received coils have been relevelled using two different leveler set-ups and tensile tests have been performed using both initial and final material states. Aiming to quantify the effect of the material hardening on a real forming process, a new tangential bending prototype has been developed. As received and levelled precuts have been bent and the forming torques and the postforming angles have been compared.

Integrated PET/MR breast cancer imaging: Attenuation correction and implementation of a 16-channel RF coil

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

Oehmigen, Mark, E-mail: mark.oehmigen@uni-due.de

Purpose: This study aims to develop, implement, and evaluate a 16-channel radiofrequency (RF) coil for integrated positron emission tomography/magnetic resonance (PET/MR) imaging of breast cancer. The RF coil is designed for optimized MR imaging performance and PET transparency and attenuation correction (AC) is applied for accurate PET quantification. Methods: A 16-channel breast array RF coil was designed for integrated PET/MR hybrid imaging of breast cancer lesions. The RF coil features a lightweight rigid design and is positioned with a spacer at a defined position on the patient table of an integrated PET/MR system. Attenuation correction is performed by generating andmore » applying a dedicated 3D CT-based template attenuation map. Reposition accuracy of the RF coil on the system patient table while using the positioning frame was tested in repeated measurements using MR-visible markers. The MR, PET, and PET/MR imaging performances were systematically evaluated using modular breast phantoms. Attenuation correction of the RF coil was evaluated with difference measurements of the active breast phantoms filled with radiotracer in the PET detector with and without the RF coil in place, serving as a standard of reference measurement. The overall PET/MR imaging performance and PET quantification accuracy of the new 16-channel RF coil and its AC were then evaluated in first clinical examinations on ten patients with local breast cancer. Results: The RF breast array coil provides excellent signal-to-noise ratio and signal homogeneity across the volume of the breast phantoms in MR imaging and visualizes small structures in the phantoms down to 0.4 mm in plane. Difference measurements with PET revealed a global loss and thus attenuation of counts by 13% (mean value across the whole phantom volume) when the RF coil is placed in the PET detector. Local attenuation ranging from 0% in the middle of the phantoms up to 24% was detected in the peripheral regions of the phantoms at positions closer to attenuating hardware structures of the RF coil. The position accuracy of the RF coil on the patient table when using the positioning frame was determined well below 1 mm for all three spatial dimensions. This ensures perfect position match between the RF coil and its three-dimensional attenuation template during the PET data reconstruction process. When applying the CT-based AC of the RF coil, the global attenuation bias was mostly compensated to ±0.5% across the entire breast imaging volume. The patient study revealed high quality MR, PET, and combined PET/MR imaging of breast cancer. Quantitative activity measurements in all 11 breast cancer lesions of the ten patients resulted in increased mean difference values of SUV{sub max} 11.8% (minimum 3.2%; maximum 23.2%) between nonAC images and images when AC of the RF breast coil was applied. This supports the quantitative results of the phantom study as well as successful attenuation correction of the RF coil. Conclusions: A 16-channel breast RF coil was designed for optimized MR imaging performance and PET transparency and was successfully integrated with its dedicated attenuation correction template into a whole-body PET/MR system. Systematic PET/MR imaging evaluation with phantoms and an initial study on patients with breast cancer provided excellent MR and PET image quality and accurate PET quantification.« less

Critical heat flux test apparatus

DOEpatents

Welsh, Robert E.; Doman, Marvin J.; Wilson, Edward C.

1992-01-01

An apparatus for testing, in situ, highly irradiated specimens at high temperature transients is provided. A specimen, which has a thermocouple device attached thereto, is manipulated into test position in a sealed quartz heating tube by a robot. An induction coil around a heating portion of the tube is powered by a radio frequency generator to heat the specimen. Sensors are connected to monitor the temperatures of the specimen and the induction coil. A quench chamber is located below the heating portion to permit rapid cooling of the specimen which is moved into this quench chamber once it is heated to a critical temperature. A vacuum pump is connected to the apparatus to collect any released fission gases which are analyzed at a remote location.

NASA TechPort Entry for Coiled Brine Recovery Assembly (CoBRA) CL IR&D Project

NASA Technical Reports Server (NTRS)

Pensinger, Stuart

2014-01-01

The Coiled Brine Recovery Assembly (CoBRA) project will result in a proof-of-concept demonstration for a lightweight, compact, affordable, regenerable and disposable solution to brine water recovery. The heart of CoBRA is an evaporator that produces water vapor from brine. This evaporator leverages a novel design that enables passive transport of brine from place to place within the system. While it will be necessary to build or modify a system for testing the CoBRA concept, the emphasis of this project will be on developing the evaporator itself. This project will utilize a “test early, test often” approach, building at least one trial evaporator to guide the design of the final product.

Evaluation of CFD Methods for Simulation of Two-Phase Boiling Flow Phenomena in a Helical Coil Steam Generator

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

Pointer, William David; Shaver, Dillon; Liu, Yang

The U.S. Department of Energy, Office of Nuclear Energy charges participants in the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program with the development of advanced modeling and simulation capabilities that can be used to address design, performance and safety challenges in the development and deployment of advanced reactor technology. The NEAMS has established a high impact problem (HIP) team to demonstrate the applicability of these tools to identification and mitigation of sources of steam generator flow induced vibration (SGFIV). The SGFIV HIP team is working to evaluate vibration sources in an advanced helical coil steam generator using computational fluidmore » dynamics (CFD) simulations of the turbulent primary coolant flow over the outside of the tubes and CFD simulations of the turbulent multiphase boiling secondary coolant flow inside the tubes integrated with high resolution finite element method assessments of the tubes and their associated structural supports. This report summarizes the demonstration of a methodology for the multiphase boiling flow analysis inside the helical coil steam generator tube. A helical coil steam generator configuration has been defined based on the experiments completed by Polytecnico di Milano in the SIET helical coil steam generator tube facility. Simulations of the defined problem have been completed using the Eulerian-Eulerian multi-fluid modeling capabilities of the commercial CFD code STAR-CCM+. Simulations suggest that the two phases will quickly stratify in the slightly inclined pipe of the helical coil steam generator. These results have been successfully benchmarked against both empirical correlations for pressure drop and simulations using an alternate CFD methodology, the dispersed phase mixture modeling capabilities of the open source CFD code Nek5000.« less

2-d and 1-d Nanomaterials Construction through Peptide Computational Design and Solution Assembly

NASA Astrophysics Data System (ADS)

Pochan, Darrin

Self-assembly of molecules is an attractive materials construction strategy due to its simplicity in application. By considering peptidic molecules in the bottom-up materials self-assembly design process, one can take advantage of inherently biomolecular attributes; intramolecular folding events, secondary structure, and electrostatic/H-bonding/hydrophobic interactions to define hierarchical material structure and consequent properties. Importantly, while biomimicry has been a successful strategy for the design of new peptide molecules for intermolecular assembly, computational tools have been developed to de novo design peptide molecules required for construction of pre-determined, desired nanostructures and materials. A new system comprised of coiled coil bundle motifs theoretically designed to assemble into designed, one and two-dimensional nanostructures will be introduced. The strategy provides the opportunity for arbitrary nanostructure formation, i.e. structures not observed in nature, with peptide molecules. Importantly, the desired nanostructure was chosen first while the peptides needed for coiled coil formation and subsequent nanomaterial formation were determined computationally. Different interbundle, two-dimensional nanostructures are stabilized by differences in amino acid composition exposed on the exterior of the coiled coil bundles. Computation was able to determine molecules required for different interbundle symmetries within two-dimensional sheets stabilized by subtle differences in amino acid composition of the inherent peptides. Finally, polymers were also created through covalent interactions between bundles that allowed formation of architectures spanning flexible network forming chains to ultra-stiff polymers, all with the same building block peptides. The success of the computational design strategy is manifested in the nanomaterial results as characterized by electron microscopy, scattering methods, and biophysical techniques. Support from NSF DMREF program under awards DMR-1234161 and DMR-1235084.

Design and Testing of the ARL Squeeze 4 Helical Flux Compression Generator

DTIC Science & Technology

2013-06-01

armature makes contact. Centering the armature inside the coil was accomplished with three machined polyurethane (4 lb/ft3 Lastafoam)3 foam rings. A...after shrinking was ~1 mm thick. The explosive charge was comprised of a paper- reinforced phenolic cylinder filled with Comp-B explosive fill. The...backfilled with polyester resin. Foam rubber was placed between coil windings (figure 3a). All other subsequent experiments used a custom rapid-prototyped

Promoted-Combustion Chamber with Induction Heating Coil

NASA Technical Reports Server (NTRS)

Richardson, Erin; Hagood, Richard; Lowery, Freida; Herald, Stephen

2006-01-01

An improved promoted-combustion system has been developed for studying the effects of elevated temperatures on the flammability of metals in pure oxygen. In prior promoted-combustion chambers, initial temperatures of metal specimens in experiments have been limited to the temperatures of gas supplies, usually near room temperature. Although limited elevated temperature promoted-combustion chambers have been developed using water-cooled induction coils for preheating specimens, these designs have been limited to low-pressure operation due to the hollow induction coil. In contrast, the improved promoted-combustion chamber can sustain a pressure up to 10 kpsi (69 MPa) and, through utilization of a solid induction coil, is capable of preheating a metal specimen up to its melting point [potentially in excess of 2,000 F (approximately equal to 1,100 C)]. Hence, the improved promoted combustion chamber makes a greater range of physical conditions and material properties accessible for experimentation. The chamber consists of a vertical cylindrical housing with an inner diameter of 8 in. (20.32 cm) and an inner height of 20.4 in. (51.81 cm). A threaded, sealing cover at one end of the housing can be unscrewed to gain access for installing a specimen. Inlet and outlet ports for gases are provided. Six openings arranged in a helical pattern in the chamber wall contain sealed sapphire windows for viewing an experiment in progress. The base of the chamber contains pressure-sealed electrical connectors for supplying power to the induction coil. The connectors feature a unique design that prevents induction heating of the housing and the pressure sealing surfaces; this is important because if such spurious induction heating were allowed to occur, chamber pressure could be lost. The induction coil is 10 in. (25.4 cm) long and is fitted with a specimen holder at its upper end. At its lower end, the induction coil is mounted on a ceramic base, which affords thermal insulation to prevent heating of the base of the chamber during use. A sapphire cylinder protects the coil against slag generated during an experiment. The induction coil is energized by a 6-kW water-cooled power supply operating at a frequency of 400 kHz. The induction coil is part of a parallel-tuned circuit, the tuning of which is used to adjust the coupling of power to the specimen. The chamber is mounted on a test stand along with pumps, valves, and plumbing for transferring pressurized gas into and out of the chamber. In addition to multiple video cameras aimed through the windows encircling the chamber, the chamber is instrumented with gauges for monitoring the progress of an experiment. One of the gauges is a dual-frequency infrared temperature transducer aimed at the specimen through one window. Chamber operation is achieved via a console that contains a computer running apparatus-specific software, a video recorder, and real-time video monitors. For safety, a blast wall separates the console from the test stand.

Influence of coil current modulation on polycrystalline diamond film deposition by irradiation of Ar/CH4/H2 inductively coupled thermal plasmas

NASA Astrophysics Data System (ADS)

Betsuin, Toshiki; Tanaka, Yasunori; Arai, T.; Uesugi, Y.; Ishijima, T.

2018-03-01

This paper describes the application of an Ar/CH4/H2 inductively coupled thermal plasma with and without coil current modulation to synthesise diamond films. Induction thermal plasma with coil current modulation is referred to as modulated induction thermal plasma (M-ITP), while that without modulation is referred to as non-modulated ITP (NM-ITP). First, spectroscopic observations of NM-ITP and M-ITP with different modulation waveforms were made to estimate the composition in flux from the thermal plasma by measuring the time evolution in the spectral intensity from the species. Secondly, we studied polycrystalline diamond film deposition tests on a Si substrate, and we studied monocrystalline diamond film growth tests using the irradiation of NM-ITP and M-ITP. From these tests, diamond nucleation effects by M-ITP were found. Finally, following the irradiation results, we attempted to use a time-series irradiation of M-ITP and NM-ITP for polycrystalline diamond film deposition on a Si substrate. The results indicated that numerous larger diamond particles were deposited with a high population density on the Si substrate by time-series irradiation.

Education Demonstration Equipment

NASA Astrophysics Data System (ADS)

Nagy, A.; Lee, R. L.

2005-10-01

Several GA Fusion Education Program plasma related demonstration items were developed this year. A 120 V ac powered electromagnetic coil shows eddy current levitation over an aluminum sheet and continuously changing magnetic force interactions using additional permanent magnets. A 300 V dc plasma device, with variable current capability and analog data ports, is used to develop plasma I/V plots. An on-demand (via push button) fully enclosed 24 in. Jacob's ladder provides air plasma and buoyancy effects. A low cost Mason jar vacuum chamber filled with inert gas shows pressure and gas species plasma characteristics when excited by a Tesla coil. These demonstration items are used in the Scientist-In-the-Classroom program, GA facility tours, and teacher seminars to present plasma to students and teachers. Three very popular Build-It workshops were held to enable teachers to build these items and take them back to their classroom.

Magic-Angle-Spinning NMR Magnet Development: Field Analysis and Prototypes

PubMed Central

Voccio, John; Hahn, Seungyong; Park, Dong Keun; Ling, Jiayin; Kim, Youngjae; Bascuñán, Juan; Iwasa, Yukikazu

2013-01-01

We are currently working on a program to complete a 1.5 T/75 mm RT bore magic-angle-spinning nuclear magnetic resonance magnet. The magic-angle-spinning magnet comprises a z-axis 0.866-T solenoid and an x-axis 1.225-T dipole, each to be wound with NbTi wire and operated at 4.2 K in persistent mode. A combination of the fields creates a 1.5-T field pointed at 54.74 degrees (magic angle) from the rotation (z) axis. In the first year of this 3-year program, we have completed magnetic analysis and design of both coils. Also, using a winding machine of our own design and fabrication, we have wound several prototype dipole coils with NbTi wire. As part of this development, we have repeatedly made successful persistent NbTi-NbTi joints with this multifilamentary NbTi wire. PMID:24058275

Development of a Split Bitter-type Magnet System for Dusty Plasma Experiments

NASA Astrophysics Data System (ADS)

Bates, Evan; Romero-Talamas, Carlos A.; Birmingham, William J.; Rivera, William F.

2014-10-01

A 10 Tesla Bitter-type magnetic system is under development at the Dusty Plasma Laboratory of the University of Maryland, Baltimore County (UMBC). We present here an optimization technique that uses differential evolution to minimize the omhic heating produced by the coils, while constraining the magnetic field in the experimental volume. The code gives us the optimal dimensions for the coil system including: coil length, turn thickness, disks radii, resistance, and total current required for a constant magnetic field. Finite element parametric optimization is then used to establish the optimal design for water cooling holes. Placement of the cooling holes will also take into consideration the magnetic forces acting on the copper alloy disks to ensure the material strength is not compromised during operation. The proposed power and cooling water delivery subsystems for the coils are also presented. Upon completion and testing of the magnet system, planned experiments include the propagation of magnetized waves in dusty plasma crystals under various boundary conditions, and viscosity in rotational shear flow, among others.

MFP1 is a thylakoid-associated, nucleoid-binding protein with a coiled-coil structure

PubMed Central

Jeong, Sun Yong; Rose, Annkatrin; Meier, Iris

2003-01-01

Plastid DNA, like bacterial and mitochondrial DNA, is organized into protein–DNA complexes called nucleoids. Plastid nucleoids are believed to be associated with the inner envelope in developing plastids and the thylakoid membranes in mature chloroplasts, but the mechanism for this re-localization is unknown. Here, we present the further characterization of the coiled-coil DNA-binding protein MFP1 as a protein associated with nucleoids and with the thylakoid membranes in mature chloroplasts. MFP1 is located in plastids in both suspension culture cells and leaves and is attached to the thylakoid membranes with its C-terminal DNA-binding domain oriented towards the stroma. It has a major DNA-binding activity in mature Arabidopsis chloroplasts and binds to all tested chloroplast DNA fragments without detectable sequence specificity. Its expression is tightly correlated with the accumulation of thylakoid membranes. Importantly, it is associated in vivo with nucleoids, suggesting a function for MFP1 at the interface between chloroplast nucleoids and the developing thylakoid membrane system. PMID:12930969

Magnetic particle testing of turbine blades mounted on the turbine rotor shaft

NASA Astrophysics Data System (ADS)

Imbert, Clement; Rampersad, Krishna

1992-07-01

An outline is presented of the general technique of magnetic particle inspection (MPI) of turbine blades mounted on the turbine rotor shaft with specific reference to the placement of the magnetizing coils. In particular, this study reports on the use of MPI in the examination of martensitic stainless steel turbine blades in power plants in Trinidad and Tobago in order to establish procedures for the detection of discontinuities. The techniques described are applicable to ferromagnetic turbine blades in general. The two practical techniques mentioned are the method of placing a preformed coil over a number of blades in one row and the method of wrapping the coil around the rotor shaft across an entire row of blades. Of the two methods, the former is preferred to the latter one, because there is greater uniformity of magnetic flux induced and lower current required to induce adequate flux density with the preformed coil. However, both methods provide satisfactory magnetic flux, and either can be used.

Structured Cable for High-Current Coils of Tokamaks

NASA Astrophysics Data System (ADS)

Benson, Christopher; McIntyre, Peter; Sattarov, Akhdiyor; Mann, Thomas

2011-10-01

The 45 kA superconducting cable for the ITER central solenoid coil has yielded questionable results in two recent tests. In both cases the cable Tc increased after cycling only a fraction of the design life, indicating degradation due to fatigue and fracture among the superconducting strands. The Accelerator Research Lab at Texas A&M University is developing a design for a Nb3Sn structured cable suitable for such tokamak coils. The superconductor is configured in 6 sub-cables, and each subcable is supported within a channel of a central support structure within a high-strength armor sheath. The structured cable addresses two issues that are thought to compromise opposition at high current. The strands are supported without cross-overs (which produce stress concentration); and armor sheath and core structure bypass stress through the coil and among subcables so that the stress within each subcable is only what is produced directly upon it. Details of the design and plans for development will be presented.

A superconducting large-angle magnetic suspension

NASA Technical Reports Server (NTRS)

Downer, James; Goldie, James; Torti, Richard

1991-01-01

The component technologies were developed required for an advanced control moment gyro (CMG) type of slewing actuator for large payloads. The key component of the CMG is a large-angle magnetic suspension (LAMS). The LAMS combines the functions of the gimbal structure, torque motors, and rotor bearings of a CMG. The LAMS uses a single superconducting source coil and an array of cryoresistive control coils to produce a specific output torque more than an order of magnitude greater than conventional devices. The designed and tested LAMS system is based around an available superconducting solenoid, an array of twelve room-temperature normal control coils, and a multi-input, multi-output control system. The control laws were demonstrated for stabilizing and controlling the LAMS system.

Manufacturing of a superconducting magnet system for 28 GHz electron cyclotron resonance ion source at KBSI.

PubMed

Lee, B S; Choi, S; Yoon, J H; Park, J Y; Won, M S

2012-02-01

A magnet system for a 28 GHz electron cyclotron resonance ion source is being developed by the Korea Basic Science Institute. The configuration of the magnet system consists of 3 solenoid coils for a mirror magnetic field and 6 racetrack coils for a hexapole magnetic field. They can generate axial magnetic fields of 3.6 T at the beam injection part and 2.2 T at the extraction part. A radial magnetic field of 2.1 T is achievable at the plasma chamber wall. A step type winding process was employed in fabricating the hexapole coil. The winding technique was confirmed through repeated cooling tests. Superconducting magnets and a cryostat system are currently being manufactured.

Characterization of Detonator Performance as a Function of Porosity via the Hayes Effect via Rogowski Coil

NASA Astrophysics Data System (ADS)

Nakamoto, Teagan; Parrack, Kristina; Smith, Dalton; Trujillo, Chris; Wilde, Zak; Gibson, John; Lodes, Rylie; Malcolm, Hayden

2017-06-01

Researchers experimented with a novel diagnostic to study the effects of porosity on detonator performance. The new diagnostic takes advantage of the detonation electric effect observed by Hayes (1966). Detonation-produced electrical charges induce a current in the detonator wire that may be detected by use of a Rogowski coil developed and tailored for the purpose. Data collected by the Rogowski coil were then used to characterize detonations. Researchers tested PETN charges of various porosity levels (as characterized by measured particle size and surface area) to study the effect of porosity on detonation characteristics. This novel method was compared with and verified by the well-established technique of using PVDF gauges for detonator response characterization.

Experimental investigation of cooling perimeter and disturbance length effect on stability of Nb3Sn cable-in-conduit conductors

NASA Astrophysics Data System (ADS)

Armstrong, J. R.

1992-02-01

The stability of three coils, with similar parameters besides having differing strand diameters, was investigated experimentally using inductive heaters to input disturbances. One of the coils stability was also tested by doubling the inductive heated disturbance length to 10 cm. By computationally deriving approximate inductive heater input energy at 12 T, stability curves show fair agreement with zero-dimensional and one-dimensional computer predictions. Quench velocity and limiting currents also show good agreement with earlier work. Also, the stability measured on one of the coils below its limiting current by disturbing a 10 cm length of conductor was much less than the same samples stability using a 5 cm disturbance length.

Spool piece aperture: warm to cold temperature position changes

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

McInturff, A.D.

1982-12-01

In an effort to determine the position of the correction coil system contained in the spool piece in operation, a series of experiments were done in Lab 2 during the cryogenic testing of the spools. A special turn-around box was constructed which had a window through which a sighting could be made of the aperture of the coil packages. A set of four survey monuments were constructed with three point suspension, which were back-lighted by placing a small bulb behind each target which could be turned on individually external to the spool string while under vacuum and at any temperature.more » The targets were located at the ends of each correction coil package in their beam tube.« less

Method and apparatus for identifying conductive objects by monitoring the true resistive component of impedance change in a coil system caused by the object

DOEpatents

Gregory, William D.; Capots, Larry H.; George, James P.; Janik, Richard

1981-01-01

The type of conductor, its property, and if a metal, its type and cross-sectional area can be obtained from measurements made at different frequencies for the amount of unbalance created in a previously balanced stable coil detection system. The true resistive component is accurately measured and thus reflects only the voltage loss attributable to eddy currents caused by introduction of the test sample to the coil system. This voltage divided by corresponding applied frequency gives a curve which peaks at a frequency dependent upon type of conductor. For a metal this peak frequency is proportional to the samples resistivity divided by its cross-sectional area.

Eddy Current Method for Fatigue Testing

NASA Technical Reports Server (NTRS)

Simpson, John W. (Inventor); Fulton, James P. (Inventor); Wincheski, Russell A. (Inventor); Todhunter, Ronald G. (Inventor); Namkung, Min (Inventor); Nath, Shridhar C. (Inventor)

1997-01-01

Flux-focusing electromagnetic sensor using a ferromagnetic flux-focusing lens simplifies inspections and increases detectability of fatigue cracks and material loss in high conductivity material. A ferrous shield isolates a high-turn pick-up coil from an excitation coil. Use of the magnetic shield produces a null voltage output across the receiving coil in presence of an unflawed sample. Redistribution of the current flow in the sample caused by the presence of flaws. eliminates the shielding condition and a large output voltage is produced, yielding a clear unambiguous flaw signal. Maximum sensor output is obtained when positioned symmetrically above the crack. By obtaining position of maximum sensor output, it is possible to track the fault and locate the area surrounding its tip. Accuracy of tip location is enhanced by two unique features of the sensor; a very high signal-to-noise ratio of the probe's output resulting in an extremely smooth signal peak across the fault, and a rapidly decaying sensor output outside a small area surrounding the crack tip enabling the search region to be clearly defined. Under low frequency operation, material thinning due to corrosion causes incomplete shielding of the pick-up coil. Low frequency output voltage of the probe is therefore a direct indicator of thickness of the test sample. Fatigue testing a conductive material is accomplished by applying load to the material, applying current to the sensor, scanning the material with the sensor, monitoring the sensor output signal, adjusting material load based on the sensor output signal of the sensor, and adjusting position of the sensor based on its output signal.

MR coil sensitivity inhomogeneity correction for plaque characterization in carotid arteries

NASA Astrophysics Data System (ADS)

Salvado, Olivier; Hillenbrand, Claudia; Suri, Jasjit; Wilson, David L.

2004-05-01

We are involved in a comprehensive program to characterize atherosclerotic disease using multiple MR images having different contrast mechanisms (T1W, T2W, PDW, magnetization transfer, etc.) of human carotid and animal model arteries. We use specially designed intravascular and surface array coils that give high signal-to-noise but suffer from sensitivity inhomogeneity. With carotid surface coils, challenges include: (1) a steep bias field with an 80% change; (2) presence of nearby muscular structures lacking high frequency information to distinguish bias from anatomical features; (3) many confounding zero-valued voxels subject to fat suppression, blood flow cancellation, or air, which are not subject to coil sensitivity; and (4) substantial noise. Bias was corrected using a modification of the adaptive fuzzy c-mean method reported by Pham et al. (IEEE TMI, 18:738-752), whereby a bias field modeled as a mechanical membrane was iteratively improved until cluster means no longer changed. Because our images were noisy, we added a noise reduction filtering step between iterations and used about 5 classes. In a digital phantom having a bias field measured from our MR system, variations across an area comparable to a carotid artery were reduced from 50% to <5% with processing. Human carotid images were qualitatively improved and large regions of skeletal muscle were relatively flat. Other commonly applied techniques failed to segment the images or introduced strong edge artifacts. Current evaluations include comparisons to bias as measured by a body coil in human MR images.

A Simple Spreadsheet Program to Simulate and Analyze the Far-UV Circular Dichroism Spectra of Proteins

ERIC Educational Resources Information Center

Abriata, Luciano A.

2011-01-01

A simple algorithm was implemented in a spreadsheet program to simulate the circular dichroism spectra of proteins from their secondary structure content and to fit [alpha]-helix, [beta]-sheet, and random coil contents from experimental far-UV circular dichroism spectra. The physical basis of the method is briefly reviewed within the context of…

Improved Tubulars for Better Economics in Deep Gas Well Drilling using Microwave Technology

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

Dinesh Agrawal; Paul Gigl; Mahlon Dennis

2006-02-01

The objective of the research program has been to improve the rate-of-penetration in deep hostile environments by improving the life cycle and performance of coiled-tubing, an important component of a deep well drilling system for oil and gas exploration. The current process of the manufacture long tubular steel products consists of shaping the tube from flat strip, welding the seam and sections into lengths that can be miles long, and coiling onto reels. However, the welds, that are a weak point, now limit the performance of the coil tubing. This is not only from a toughness standpoint but also frommore » a corrosion standpoint. By utilizing the latest developments in the sintering of materials with microwave energy and powder metal extrusion technology for the manufacture of seamless coiled tubing and other tubular products, these problems can be eliminated. The project is therefore to develop a continuous microwave process to sinter continuously steel tubulars and butt-join them using microwave/induction process. The program started about three years ago and now we are in the middle of Phase II. In Phase I (which ended in February 2005) a feasibility study of the extrusion process of steel powder and continuously sinter the extruded tubing was conducted. The research program has been based on the development of microwave technology to process tubular specimens of powder metals, especially steels. The existing microwave systems at the Materials Research Laboratory (MRL) and Dennis Tool Company (DTC) were suitably modified to process tubular small specimens. The precursor powder metals were either extruded or cold isostatically pressed (CIP) to form tubular specimens. After conducting an extensive and systematic investigation of extrusion process for producing long tubes, it was determined that there were several difficulties in adopting extrusion process and it cannot be economically used for producing thousands of feet long green tubing. Therefore, in the Phase II the approach was modified to the microwave sintering combined with Cold Isostatic Press (CIP) and joining (by induction or microwave). This process can be developed into a semi-continuous sintering process if the CIP can produce parts fast enough to match the microwave sintering rates. This report summarizes the progress made to-date in this new approach. The final steel composition matching with the Quality tubing's QT-16Cr80 was short listed and used for all experiments. Bonding experiments using 4 different braze powders were conducted and the process optimized to obtain high degree of bonding strength. For fabrication of green tubulars a large CIP unit was acquired and tested. This equipment is located at the Dennis Tool facility in Houston. Microwave sintering experiments for continuous processing of the CIPed tubes are under progress in order to identify the optimum conditions. There have been some reproducibility problems and we are at present working to resolve these problems.« less

Field Testing, Installation, and Calibration of a new Data Acquisition System for the USGS-Stanford-Berkley Ultra-Low Frequency Electromagnetic (ULFEM) Array

NASA Astrophysics Data System (ADS)

Creasy, N.; Gardner, J.; Spritzer, J. M.; Keneally, I.; Glen, J. M.; McPhee, D.; Klemperer, S. L.

2013-12-01

Since 2006, Stanford University, USGS, and UC Berkeley collaboratively maintain five permanent stations, to measure electric and magnetic data from 0.01 to 40Hz. Each station consists of three orthogonal coil magnetometers and two orthogonal 100m electrodes. The acquisition of ULFEM data helps study possible correlations between electromagnetic fields and seismic events related to the San Andreas Fault system. The current data acquisition system uses a Quanterra Q330 analog-to-digital converter. In 2010, we began development of a new 24-bit digitizing system known as the ULFEM 2010 digitizer in order to replace the Q330. The design of the new recorder was to be more economical and better tailored to the ULFEM network by providing power, calibration, and improved protection from lightning. However, the prototype had many problems, including a daily phase shift, amplifying error, and a time delay of 15 seconds (Bowden, et al., AGU, 2010). Currently, comparative testing of an improved prototype, ULFEM 2013, and the Q330 is taking place at the Jasper Ridge ULFEM station. The ULFEM 2013 contains eight channels that record input from three coil magnetometers, four electrodes, and temperature. Testing is ongoing and involves comparing the coil magnetometer and electrode signals processed by the Q330 and ULFEM 2013 digitizer. Data from the two systems will be compared in the time and frequency domains, and analyses will include calculating error and cross correlations. The ULFEM 2013 digitizer provides power to the magnetometer sensors as well as a calibration coil system (CCS). Every 24 hours, the CCS sends a calibration signal to calibration induction coils fitted to each of the three orthogonal magnetometers with the aim of testing the sensors' sensitivity and accuracy. The CCS produces a frequency sweep of 0.08, 0.51, 5, and 10Hz, creating a field nearly ten times greater than the Earth's field. The CCS consists of open source hardware and an amplifying frequency generator. Another ongoing effort to calibrate the ULFEM stations uses ground motion produced by distant earthquakes. Because of our stations' relatively close proximity (approximately 70km apart), teleseismic earthquakes at epicentral distances produce near-identical long-period seismic arrivals at each ULFEM station. The ground motion generated by the surface waves of distant earthquakes causes displacement of the induction coils, inducing magnetic anomalies in the recorded data. Because the ground motion has nearly the same characteristics at each station, the magnetic anomalies observed should have similar amplitudes regardless of the station (though modulated by the local conductivity structure at each site). To identify these coseismic signals, magnetic data were compared against seismic data from each station. Magnetic signals are clearly visible due to passage of Love and Rayleigh waves from teleseismic earthquakes of magnitude >7.4 and their relative amplitudes provide additional confirmation of the stability of our coils and recording system prior to the installation of the CCS.

Comparison of TOF MRA, Contrast-Enhanced MRA and Subtracted CTA from CTP in Residue Evaluation of Treated Intracranial Aneurysms.

PubMed

Dündar, Tolga Turan; Aralaşmak, Ayşe; Özdemir, Hüseyin; Seyithanoğlu, Mehmet Hakan; Uysal, Ömer; Toprak, Hüseyin; Kitiş, Serkan; Özek, Erdinç; Alkan, Alpay

2017-10-18

To compare effectiveness of contrast-enhanced MRA (CE-MRA), 3D-Time-of-flight MRA (3D-TOF-MRA) and subtracted CTA from CTP (sub-CTA) in residue evaluation of intracranial aneurysms treated either with coiling or clipping. Sixteen treated aneurysms, which were evaluated with three methods within two weeks after the operation, were enrolled. The success of each imaging techniques in demonstration of residue aneurysm and nearby vessels was compared by Fisher\\'s Exact Test. The differences among three was evaluated by Cochran\\'s Q test (p ≤ 0.05). Perfusion abnormality was noted in % 81 of clipped and none of coiled patients. Vessel visualization in the vicinity of aneurysm was better in sub-CTA, followed by CE-MRA. In clipped aneurysms, sub-CTA revealed residue aneurysms in % 16,7 of the patients while 3D-TOF-MRA and CE-MRA revealed none. In coiled aneurysms, CE-MRA revealed residue aneurysms in 100 %, and TOF-MRA in 33,3 % while sub-CTA revealed none. Although dramatic differences were noted in the evaluation of residue aneurysm as well as nearby vessel visualization, no statistical significance noted due to very few patients in subcategories Conclusion: This is first study comparing the effectiveness of CE-MRA, 3D-TOF MRA and sub-CTA in residue aneurysms evaluation. Vessel visualization in the vicinity of aneurysm was better in sub-CTA in all regardless of coiling or clipping. Residue aneurysms were more commonly revealed by CE-MRA in coiled patients and more commonly and better shown by sub-CTA in clipped patients in addition of showing perfusion abnormality that's is more common in clipped patients.

Neurostimulation systems for deep brain stimulation: in vitro evaluation of magnetic resonance imaging-related heating at 1.5 tesla.

PubMed

Rezai, Ali R; Finelli, Daniel; Nyenhuis, John A; Hrdlicka, Greg; Tkach, Jean; Sharan, Ashwini; Rugieri, Paul; Stypulkowski, Paul H; Shellock, Frank G

2002-03-01

To assess magnetic resonance imaging (MRI)-related heating for a neurostimulation system (Activa Tremor Control System, Medtronic, Minneapolis, MN) used for chronic deep brain stimulation (DBS). Different configurations were evaluated for bilateral neurostimulators (Soletra Model 7426), extensions, and leads to assess worst-case and clinically relevant positioning scenarios. In vitro testing was performed using a 1.5-T/64-MHz MR system and a gel-filled phantom designed to approximate the head and upper torso of a human subject. MRI was conducted using the transmit/receive body and transmit/receive head radio frequency (RF) coils. Various levels of RF energy were applied with the transmit/receive body (whole-body averaged specific absorption rate (SAR); range, 0.98-3.90 W/kg) and transmit/receive head (whole-body averaged SAR; range, 0.07-0.24 W/kg) coils. A fluoroptic thermometry system was used to record temperatures at multiple locations before (1 minute) and during (15 minutes) MRI. Using the body RF coil, the highest temperature changes ranged from 2.5 degrees-25.3 degrees C. Using the head RF coil, the highest temperature changes ranged from 2.3 degrees-7.1 degrees C.Thus, these findings indicated that substantial heating occurs under certain conditions, while others produce relatively minor, physiologically inconsequential temperature increases. The temperature increases were dependent on the type of RF coil, level of SAR used, and how the lead wires were positioned. Notably, the use of clinically relevant positioning techniques for the neurostimulation system and low SARs commonly used for imaging the brain generated little heating. Based on this information, MR safety guidelines are provided. These observations are restricted to the tested neurostimulation system.

Development of a compact HTS lead unit for the SC correction coils of the SuperKEKB final focusing magnet system

NASA Astrophysics Data System (ADS)

Zong, Zhanguo; Ohuchi, Norihito; Tsuchiya, Kiyosumi; Arimoto, Yasushi

2016-09-01

Forty-three superconducting (SC) correction coils with maximum currents of about 60 A are installed in the SuperKEKB final focusing magnet system. Current leads to energize the SC correction coils should have an affordable heat load and fit the spatial constraints in the service cryostat where the current leads are installed. To address the requirements, design optimization of individual lead was performed with vapor cooled current lead made of a brass material, and a compact unit was designed to accommodate eight current leads together in order to be installed with one port in the service cryostat. The 2nd generation high temperature SC (HTS) tape was adopted and soldered at the cold end of the brass current lead to form a hybrid HTS lead structure. A prototype of the compact lead unit with HTS tape was constructed and tested with liquid helium (LHe) environment. This paper presents a cryogenic measurement system to simulate the real operation conditions in the service cryostat, and analysis of the experimental results. The measured results showed excellent agreement with the theoretical analysis and numerical simulation. In total, 11 sets of the compact HTS lead units were constructed for the 43 SC correction coils at KEK. One set from the mass production was tested in cryogenic conditions, and exhibited the same performance as the prototype. The compact HTS lead unit can feed currents to four SC correction coils simultaneously with the simple requirement of controlling and monitoring helium vapor flow, and has a heat load of about 0.762 L/h in terms of LHe consumption.

Interpreting Results from the Standardized UXO Test Sites

DTIC Science & Technology

2007-01-01

Detector Focusing Lens Cs Cell Split Polarizer Filter Collimating Lens Cs Lamp RF Coil Tiffany Mount H1 Coil Light rays Figure II-1. G-858 Cesium...conductive earth typically decay at a more rapid rate than the currents in metallic objects. Measurements are made in discrete “time gates,” or...time intervals, following the turnoff of the current pulse generated by the transmitter. The early time gates will detect both small and large metallic

Method and device for determining bond separation strength using induction heating

NASA Technical Reports Server (NTRS)

Coultrip, Robert H. (Inventor); Johnson, Samuel D. (Inventor); Copeland, Carl E. (Inventor); Phillips, W. Morris (Inventor); Fox, Robert L. (Inventor)

1994-01-01

An induction heating device includes an induction heating gun which includes a housing, a U-shaped pole piece having two spaced apart opposite ends defining a gap there between, the U-shaped pole piece being mounted in one end of the housing, and a tank circuit including an induction coil wrapped around the pole piece and a capacitor connected to the induction coil. A power source is connected to the tank circuit. A pull test machine is provided having a stationary chuck and a movable chuck, the two chucks holding two test pieces bonded together at a bond region. The heating gun is mounted on the pull test machine in close proximity to the bond region of the two test pieces, whereby when the tank circuit is energized, the two test pieces are heated by induction heating while a tension load is applied to the two test pieces by the pull test machine to determine separation strength of the bond region.

CSI 3.0: a web server for identifying secondary and super-secondary structure in proteins using NMR chemical shifts.

PubMed

Hafsa, Noor E; Arndt, David; Wishart, David S

2015-07-01

The Chemical Shift Index or CSI 3.0 (http://csi3.wishartlab.com) is a web server designed to accurately identify the location of secondary and super-secondary structures in protein chains using only nuclear magnetic resonance (NMR) backbone chemical shifts and their corresponding protein sequence data. Unlike earlier versions of CSI, which only identified three types of secondary structure (helix, β-strand and coil), CSI 3.0 now identifies total of 11 types of secondary and super-secondary structures, including helices, β-strands, coil regions, five common β-turns (type I, II, I', II' and VIII), β hairpins as well as interior and edge β-strands. CSI 3.0 accepts experimental NMR chemical shift data in multiple formats (NMR Star 2.1, NMR Star 3.1 and SHIFTY) and generates colorful CSI plots (bar graphs) and secondary/super-secondary structure assignments. The output can be readily used as constraints for structure determination and refinement or the images may be used for presentations and publications. CSI 3.0 uses a pipeline of several well-tested, previously published programs to identify the secondary and super-secondary structures in protein chains. Comparisons with secondary and super-secondary structure assignments made via standard coordinate analysis programs such as DSSP, STRIDE and VADAR on high-resolution protein structures solved by X-ray and NMR show >90% agreement between those made with CSI 3.0. © The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.

Free-piston engine linear generator for hybrid vehicles modeling study

NASA Astrophysics Data System (ADS)

Callahan, T. J.; Ingram, S. K.

1995-05-01

Development of a free piston engine linear generator was investigated for use as an auxiliary power unit for a hybrid electric vehicle. The main focus of the program was to develop an efficient linear generator concept to convert the piston motion directly into electrical power. Computer modeling techniques were used to evaluate five different designs for linear generators. These designs included permanent magnet generators, reluctance generators, linear DC generators, and two and three-coil induction generators. The efficiency of the linear generator was highly dependent on the design concept. The two-coil induction generator was determined to be the best design, with an efficiency of approximately 90 percent.

THE REAL McCOIL: A method for the concurrent estimation of the complexity of infection and SNP allele frequency for malaria parasites

PubMed Central

Chang, Hsiao-Han; Worby, Colin J.; Yeka, Adoke; Nankabirwa, Joaniter; Kamya, Moses R.; Staedke, Sarah G.; Hubbart, Christina; Amato, Roberto; Kwiatkowski, Dominic P.

2017-01-01

As many malaria-endemic countries move towards elimination of Plasmodium falciparum, the most virulent human malaria parasite, effective tools for monitoring malaria epidemiology are urgent priorities. P. falciparum population genetic approaches offer promising tools for understanding transmission and spread of the disease, but a high prevalence of multi-clone or polygenomic infections can render estimation of even the most basic parameters, such as allele frequencies, challenging. A previous method, COIL, was developed to estimate complexity of infection (COI) from single nucleotide polymorphism (SNP) data, but relies on monogenomic infections to estimate allele frequencies or requires external allele frequency data which may not available. Estimates limited to monogenomic infections may not be representative, however, and when the average COI is high, they can be difficult or impossible to obtain. Therefore, we developed THE REAL McCOIL, Turning HEterozygous SNP data into Robust Estimates of ALelle frequency, via Markov chain Monte Carlo, and Complexity Of Infection using Likelihood, to incorporate polygenomic samples and simultaneously estimate allele frequency and COI. This approach was tested via simulations then applied to SNP data from cross-sectional surveys performed in three Ugandan sites with varying malaria transmission. We show that THE REAL McCOIL consistently outperforms COIL on simulated data, particularly when most infections are polygenomic. Using field data we show that, unlike with COIL, we can distinguish epidemiologically relevant differences in COI between and within these sites. Surprisingly, for example, we estimated high average COI in a peri-urban subregion with lower transmission intensity, suggesting that many of these cases were imported from surrounding regions with higher transmission intensity. THE REAL McCOIL therefore provides a robust tool for understanding the molecular epidemiology of malaria across transmission settings. PMID:28125584

Fabrication and Assembly Performance of the First 4.2 m MQXFA Magnet and Mechanical Model for the Hi-Lumi LHC Upgrade

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

Cheng, Daniel W.; Ambrosio, Giorgio; Anderssen, Eric C.

Here, the LHC accelerator research program (LARP), in collaboration with CERN and under the scope of the high luminosity upgrade of the Large Hadron Collider, is in the prototyping stage in the development of a 150 mm aperture high-field Nb 3Sn quadrupole magnet called MQXF. This magnet is mechanically supported using a shell-based support structure, which has been extensively demonstrated on several R&D models within LARP, as well as in the more recent short (1.2 m magnetic length) MQXF model program. The MQXFA magnets are each 4.2 m magnetic length, and the first mechanical long model, MQXFA1M (using aluminum surrogatemore » coils), and MQXFAP1 prototype magnet (the first prototype with Nb 3Sn coils) have been assembled at the LBNL. In this paper, we summarize the tooling and the assembly processes, and discuss the mechanical performance of these first two assemblies, comparing strain gauge data with finite element model analysis, as well as the near-term plans for the long MQXF magnet program.« less

Fabrication and Assembly Performance of the First 4.2 m MQXFA Magnet and Mechanical Model for the Hi-Lumi LHC Upgrade

DOE PAGES

Cheng, Daniel W.; Ambrosio, Giorgio; Anderssen, Eric C.; ...

2018-01-30

Here, the LHC accelerator research program (LARP), in collaboration with CERN and under the scope of the high luminosity upgrade of the Large Hadron Collider, is in the prototyping stage in the development of a 150 mm aperture high-field Nb 3Sn quadrupole magnet called MQXF. This magnet is mechanically supported using a shell-based support structure, which has been extensively demonstrated on several R&D models within LARP, as well as in the more recent short (1.2 m magnetic length) MQXF model program. The MQXFA magnets are each 4.2 m magnetic length, and the first mechanical long model, MQXFA1M (using aluminum surrogatemore » coils), and MQXFAP1 prototype magnet (the first prototype with Nb 3Sn coils) have been assembled at the LBNL. In this paper, we summarize the tooling and the assembly processes, and discuss the mechanical performance of these first two assemblies, comparing strain gauge data with finite element model analysis, as well as the near-term plans for the long MQXF magnet program.« less

Magnetic field exposure and behavioral monitoring system.

PubMed

Thomas, A W; Drost, D J; Prato, F S

2001-09-01

To maximize the availability and usefulness of a small magnetic field exposure laboratory, we designed a magnetic field exposure system that has been used to test human subjects, caged or confined animals, and cell cultures. The magnetic field exposure system consists of three orthogonal pairs of coils 2 m square x 1 m separation, 1.751 m x 0.875 m separation, and 1.5 m x 0.75 m separation. Each coil consisted of ten turns of insulated 8 gauge stranded copper conductor. Each of the pairs were driven by a constant-current amplifier via digital to analog (D/A) converter. A 9 pole zero-gain active Bessel low-pass filter (1 kHz corner frequency) before the amplifier input attenuated the expected high frequencies generated by the D/A conversion. The magnetic field was monitored with a 3D fluxgate magnetometer (0-3 kHz, +/- 1 mT) through an analog to digital converter. Behavioral monitoring utilized two monochrome video cameras (viewing the coil center vertically and horizontally), both of which could be video recorded and real-time digitally Moving Picture Experts Group (MPEG) encoded to CD-ROM. Human postural sway (standing balance) was monitored with a 3D forceplate mounted on the floor, connected to an analog to digital converter. Lighting was provided by 12 offset overhead dimmable fluorescent track lights and monitored using a digitally connected spectroradiometer. The dc resistance, inductance of each coil pair connected in series were 1.5 m coil (0.27 Omega, 1.2 mH), 1.75 m coil (0.32 Omega, 1.4 mH), and 2 m coil (0.38 Omega, 1.6 mH). The frequency response of the 1.5 m coil set was 500 Hz at +/- 463 microT, 1 kHz at +/- 232 microT, 150 micros rise time from -200 microT(pk) to + 200 microT(pk) (square wave) and is limited by the maximum voltage ( +/- 146 V) of the amplifier (Bessel filter bypassed). Copyright 2001 Wiley-Liss, Inc.

Yttrium-90 Resin Microsphere Radioembolization Using an Antireflux Catheter: An Alternative to Traditional Coil Embolization for Nontarget Protection

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

Morshedi, Maud M., E-mail: maud.morshedi@my.rfums.org; Bauman, Michael, E-mail: mbauman@ucsd.edu; Rose, Steven C., E-mail: scrose@ucsd.edu

2015-04-15

PurposeSerious complications can result from nontarget embolization during yttrium-90 (Y-90) transarterial radioembolization. Hepatoenteric artery coil embolization has been traditionally performed to prevent nontarget radioembolization. The U.S. Food and Drug Administration–approved Surefire Infusion System (SIS) catheter, designed to prevent reflux, is an alternative to coils. The hypothesis that quantifiable SIS procedural parameters are comparable to coil embolization was tested.MethodsFourteen patients aged 36–79 years with colorectal, neuroendocrine, hepatocellular, and other predominantly bilobar hepatic tumors who underwent resin microsphere Y-90 radioembolization using only the SIS catheter (n = 7) versus only detachable coils (n = 7) for nontarget protection were reviewed retrospectively. Procedure time, fluoroscopy time, contrast dose,more » radiation dose, and cost were evaluated.ResultsMultivariate analysis identified significant cohort differences in the procedural parameters evaluated (F(10, 3) = 10.39, p = 0.04). Between-group comparisons of the pretreatment planning procedure in the SIS catheter group compared to the coil embolization group demonstrated a significant reduction in procedure time (102.6 vs. 192.1 min, respectively, p = 0.0004), fluoroscopy time (14.3 vs. 49.7 min, respectively, p = 0.0016), and contrast material dose (mean dose of 174.3 vs. 265.0 mL, respectively, p = 0.0098). Procedural parameters were not significantly different between the two groups during subsequent dose delivery procedures. Overall cost of combined first-time radioembolization procedures was significantly less in the SIS group ($4252) compared to retrievable coil embolization ($11,123; p = 0.001).ConclusionThe SIS catheter results in a reduction in procedure time, fluoroscopy time, and contrast material dose and may be an attractive cost-effective alternative to detachable coil embolization for prevention of nontarget radioembolization.« less

Power Supply Changes for NSTX Resistive Wall Mode Coils

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

Ramakrishnan, S S.

The National Spherical Torus Experiment (NSTX) has been designed and installed in the existing facilities at Princeton Plasma Physics Laboratory (PPPL). Most of the hardware, plant facilities, auxiliary sub-systems, and power systems originally used for the Tokamak Fusion Test Reactor (TFTR) have been used with suitable modifications to reflect NSTX needs. Prior to 2004, the NSTX power system was feeding twelve (12) circuits in the machine. In 2004 the Resistive Wall Mode (RWM) Coils were installed on the machine to correct error fields. There are six of these coils installed around the machine in the mid-plane. Since these coils needmore » fast and accurate controls, a Switching Power Amplifier (SPA) with three sub-units was procured, installed and commissioned along with other power loop components. Two RWM Coils were connected in series and fed from one SPA sub-unit. After the initial RWM campaign, operational requirements evolved such that each of the RWM coils now requires separate power and control. Hence a second SPA with three sub-units has been procured and installed. The second unit is of improved design and has the controls and power components completely isolated. The existing thyristor rectifier is used as DC Link to both of the Switching Power Amplifiers. The controls for the RWM are integrated into the overall computer control of the DC Power systems for NSTX. This paper describes the design changes in the RWM Power system for NSTX.« less

Wireless induction coils embedded in diamond for power transfer in medical implants.

PubMed

Sikder, Md Kabir Uddin; Fallon, James; Shivdasani, Mohit N; Ganesan, Kumaravelu; Seligman, Peter; Garrett, David J

2017-08-26

Wireless power and data transfer to medical implants is a research area where improvements in current state-of-the-art technologies are needed owing to the continuing efforts for miniaturization. At present, lithographical patterning of evaporated metals is widely used for miniature coil fabrication. This method produces coils that are limited to low micron or nanometer thicknesses leading to high impedance values and thus limiting their potential quality. In the present work we describe a novel technique, whereby trenches were milled into a diamond substrate and filled with silver active braze alloy, enabling the manufacture of small, high cross-section, low impedance microcoils capable of transferring up to 10 mW of power up to a distance of 6 mm. As a substitute for a metallic braze line used for hermetic sealing, a continuous metal loop when placed parallel and close to the coil surface reduced power transfer efficiency by 43%, but not significantly, when placed perpendicular to the microcoil surface. Encapsulation of the coil by growth of a further layer of diamond reduced the quality factor by an average of 38%, which can be largely avoided by prior oxygen plasma treatment. Furthermore, an accelerated ageing test after encapsulation showed that these coils are long lasting. Our results thus collectively highlight the feasibility of fabricating a high-cross section, biocompatible and long lasting miniaturized microcoil that could be used in either a neural recording or neuromuscular stimulation device.

Steam generator tube inspection in Japan

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

Fukui, Shigetaka

1997-02-01

Steam generator tube inspection was first carried out in 1971 at Mihama Unit-1 that is first PWR plant in Japan, when the plant was brought into the first annual inspection. At that time, inspection was made on sampling basis, and only bobbin coil probe was used. After experiencing various kinds of tube degradations, inspection method was changed from sampling to all number of tubes, and various kinds of probes were used to get higher detectability of flaw. At present, it is required that all the tubes shall be inspected in their full length at each annual inspection using standard bobbinmore » coil probe, and some special probes for certain plants that have susceptibility of occurrence of flaw. Sleeve repaired portion is included in this inspection. As a result of analyses of eddy current testing data, all indications that have been evaluated to be 20% wall thickness or deeper shall be repaired by either plugging or sleeving, where flaw morphology is to be a wastage or wear. Other types of flaw such as IGA/SCC are not allowed to be left inservice when those indications are detected. These inspections are performed according to inspection procedures that are approved by regulatory authority. Actual inspections are witnessed by the Japan Power engineering and inspection corporation (JAPEIC)`s inspectors during data acquisition and analysis, and they issue inspection report to authority for review and approval. It is achieved high safety performance of steam generator through this method of inspections, however. some tube leakage problems were experienced in the past. To prevent recurrence of such events, government is conducting development and verification test program for new eddy current testing technology.« less

Superconducting Magnetic Energy Storage (SMES) Program

NASA Astrophysics Data System (ADS)

Rogers, J. D.

1985-05-01

The 30 MJ, 10 MW superconducting magnetic energy storage (SMES) system was devised to interact in the Western US Power System as an alternate means to damp unstable oscillations at 0.35 Hz on the Pacific HVAC Interites. The operating limits of the 30 MJ SMES unit were established, and different means of controlling real and reactive power were tested. The unit can follow a sinusoidal power demand signal with an amplitude of up to 8.6 MW with the converter working in a 12 pulse mode. When the converter operates in the constant VAR mode, a time varying real power demand signal of up to 5 MW can be met. It was shown that the Pacific ac Interite has current and reactive power variations of the same frequency as the modulating frequency of the SMES device. The reliability of the SMES subsystems with a narrow band noise input was assessed. Parameters of the ac power system were determined. Converter short circuit tests, load tests under various control conditions, dc breaker tests for coil current interruption, and converter failure mode tests were conducted. The experimental operation of the SMES system is concluded.

The next large helical devices

NASA Astrophysics Data System (ADS)

Iiyoshi, Atsuo; Yamazaki, Kozo

1995-06-01

Helical systems have the strong advantage of inherent steady-state operation for fusion reactors. Two large helical devices with fully superconducting coil systems are presently under design and construction. One is the LHD (Large Helical Device) [Fusion Technol. 17, 169 (1990)] with major radius=3.9 m and magnetic field=3-4 T, that is under construction during 1990-1997 at NIFS (National Institute for Fusion Science), Nagoya/Toki, Japan; it features continuous helical coils and a clean helical divertor focusing on edge configuration optimization. The other one in the W7-X (Wendelstein 7-X) [in Plasma Physics and Controlled Fusion Nuclear Research, 1990, (International Atomic Energy Agency, Vienna, 1991), Vol. 3, p. 525] with major radius=5.5 m and magnetic field=3 T, that is under review at IPP (Max-Planck Institute for Plasma Physics), Garching, Germany; it has adopted a modular coil system after elaborate optimization studies. These two programs are complementary in promoting world helical fusion research and in extending the understanding of toroidal plasmas through comparisons with large tokamaks.

Control advances for achieving the ITER baseline scenario on KSTAR

NASA Astrophysics Data System (ADS)

Eidietis, N. W.; Barr, J.; Hahn, S. H.; Humphreys, D. A.; in, Y. K.; Jeon, Y. M.; Lanctot, M. J.; Mueller, D.; Walker, M. L.

2017-10-01

Control methodologies developed to enable successful production of ITER baseline scenario (IBS) plasmas on the superconducting KSTAR tokamak are presented: decoupled vertical control (DVC), real-time feedforward (rtFF) calculation, and multi-input multi-output (MIMO) X-point control. DVC provides fast vertical control with the in-vessel control coils (IVCC) while sharing slow vertical control with the poloidal field (PF) coils to avoid IVCC saturation. rtFF compensates for inaccuracies in offline PF current feedforward programming, allowing reduction or removal of integral gain (and its detrimental phase lag) from the shape controller. Finally, MIMO X-point control provides accurate positioning of the X-point despite low controllability due to the large distance between coils and plasma. Combined, these techniques enabled achievement of IBS parameters (q95 = 3.2, βN = 2) with a scaled ITER shape on KSTAR. n =2 RMP response displays a strong dependence upon this shaping. Work supported by the US DOE under Award DE-SC0010685 and the KSTAR project.

A measurement device for electromagnetic flow tomography

NASA Astrophysics Data System (ADS)

Vauhkonen, M.; Hänninen, A.; Lehtikangas, O.

2018-01-01

Electromagnetic flow meters have succesfully been used in many industries to measure the mean flow velocity of conductive liquids. This technology works reliably in single phase flows with axisymmetric flow profiles but can be inaccurate with asymmetric flows, which are encountered, for example, in multiphase flows, pipe elbows and T-junctions. Some computational techniques and measurement devices with multiple excitation coils and measurement electrodes have recently been proposed to be used in cases of asymmetric flows. In earlier studies, we proposed a computational approach for electromagnetic flow tomography (EMFT) for estimating velocity fields utilizing several excitation coils and a set of measurement electrodes attached to the surface of the pipe. This approach has been shown to work well with simulated data but has not been tested extensively with real measurements. In this paper, an EMFT system with four excitation coils and 16 measurement electrodes is introduced. The system is capable of using both square wave and sinusoidal coil current excitations and all the coils can be excited individually, also enabling parallel excitations with multiple frequencies. The studies undertaken in the paper demonstrate that the proposed EMFT system, together with the earlier introduced velocity field reconstruction approach, is capable of producing reliable velocify field estimates in a laboratory environment with both axisymmetric and asymmetric single phase flows.

Quench in a conduction-cooled Nb3Sn SMES magnet

NASA Astrophysics Data System (ADS)

Korpela, Aki; Lehtonen, Jorma; Mikkonen, Risto; Perälä, Raine

2003-11-01

Due to the rapid development of cryocoolers, conduction-cooled Nb3Sn devices are nowadays enabled. A 0.2 MJ conduction-cooled Nb3Sn SMES system has been designed and constructed. The nominal current of the coil was 275 A at 10 K. The quench tests have been performed and in this paper the experimental data are compared to the computational one. Due to a slow normal zone propagation, Nb3Sn magnets are not necessarily self-protective. In conduction-cooled coils, a thermal interface provides a protection method known as a quench back. The temperature rise in the coil during a quench was measured with a sensor located on the inner radius of the coil. The current decay was also monitored. The measured temperature increased for approximately 15 s after the current had already decayed. This temperature rise is due to the heat conduction from the hot spot. Thus, the measured temperature does not represent the hot-spot temperature. A computational quench model which takes into account quench back and heat conduction after the current decay was developed in order to understand the measured temperatures. According to the results, a quench back due to the eddy current induced heating of the thermal interface of an LTS coil was an adequate protection method.

Synthetic signal injection using inductive coupling

PubMed Central

Marro, Kenneth I.; Lee, Donghoon; Shankland, Eric G.; Mathis, Clinton M.; Hayes, Cecil E.; Amara, Catherine E.; Kushmerick, Martin J.

2009-01-01

Conversion of MR signals into units of metabolite concentration requires a very high level of diligence to account for the numerous parameters and transformations that affect the proportionality between the quantity of excited nuclei in the acquisition volume and the integrated area of the corresponding peak in the spectrum. We describe a method that eases this burden with respect to the transformations that occur during and following data acquisition. The conceptual approach is similar to the ERETIC method, which uses a pre-calibrated, artificial reference signal as a calibration factor to accomplish the conversion. The distinguishing feature of our method is that the artificial signal is introduced strictly via induction, rather than radiation. We tested a prototype probe that includes a second RF coil rigidly positioned close to the receive coil so that there was constant mutual inductance between them. The artificial signal was transmitted through the second RF coil and acquired by the receive coil in parallel with the real signal. Our results demonstrate that the calibration factor is immune to changes in sample resistance. This is a key advantage because it removes the cumbersome requirement that coil loading conditions be the same for the calibration sample as for experimental samples. The method should be adaptable to human studies and could allow more practical and accurate quantification of metabolite content. PMID:18595750

Synthetic signal injection using inductive coupling.

PubMed

Marro, Kenneth I; Lee, Donghoon; Shankland, Eric G; Mathis, Clinton M; Hayes, Cecil E; Amara, Catherine E; Kushmerick, Martin J

2008-09-01

Conversion of MR signals into units of metabolite concentration requires a very high level of diligence to account for the numerous parameters and transformations that affect the proportionality between the quantity of excited nuclei in the acquisition volume and the integrated area of the corresponding peak in the spectrum. We describe a method that eases this burden with respect to the transformations that occur during and following data acquisition. The conceptual approach is similar to the ERETIC method, which uses a pre-calibrated, artificial reference signal as a calibration factor to accomplish the conversion. The distinguishing feature of our method is that the artificial signal is introduced strictly via induction, rather than radiation. We tested a prototype probe that includes a second RF coil rigidly positioned close to the receive coil so that there was constant mutual inductance between them. The artificial signal was transmitted through the second RF coil and acquired by the receive coil in parallel with the real signal. Our results demonstrate that the calibration factor is immune to changes in sample resistance. This is a key advantage because it removes the cumbersome requirement that coil loading conditions be the same for the calibration sample as for experimental samples. The method should be adaptable to human studies and could allow more practical and accurate quantification of metabolite content.

Synthetic signal injection using inductive coupling

NASA Astrophysics Data System (ADS)

Marro, Kenneth I.; Lee, Donghoon; Shankland, Eric G.; Mathis, Clinton M.; Hayes, Cecil E.; Amara, Catherine E.; Kushmerick, Martin J.

2008-09-01

Conversion of MR signals into units of metabolite concentration requires a very high level of diligence to account for the numerous parameters and transformations that affect the proportionality between the quantity of excited nuclei in the acquisition volume and the integrated area of the corresponding peak in the spectrum. We describe a method that eases this burden with respect to the transformations that occur during and following data acquisition. The conceptual approach is similar to the ERETIC method, which uses a pre-calibrated, artificial reference signal as a calibration factor to accomplish the conversion. The distinguishing feature of our method is that the artificial signal is introduced strictly via induction, rather than radiation. We tested a prototype probe that includes a second RF coil rigidly positioned close to the receive coil so that there was constant mutual inductance between them. The artificial signal was transmitted through the second RF coil and acquired by the receive coil in parallel with the real signal. Our results demonstrate that the calibration factor is immune to changes in sample resistance. This is a key advantage because it removes the cumbersome requirement that coil loading conditions be the same for the calibration sample as for experimental samples. The method should be adaptable to human studies and could allow more practical and accurate quantification of metabolite content.

Protective link for superconducting coil

DOEpatents

Umans, Stephen D [Belmont, MA

2009-12-08

A superconducting coil system includes a superconducting coil and a protective link of superconducting material coupled to the superconducting coil. A rotating machine includes first and second coils and a protective link of superconducting material. The second coil is operable to rotate with respect to the first coil. One of the first and second coils is a superconducting coil. The protective link is coupled to the superconducting coil.

Destruction of the Last Good Surface in Diii-D Usn with ELMs and C-Coils Shot 115467 due to ELMs and C-Coils Using Maps

NASA Astrophysics Data System (ADS)

Sherrow, K.; Punjabi, A.; Ali, H.

2004-11-01

Unperturbed magnetic topology of DIII-D shot 115467 is described by the symmetric simple map (SSM) with parameter k=0.2623, then q_edge=6.48 (as in shot 115467) if six iterations of SSM are taken to be equivalent to single toroidal circuit of DIII-D [1]. Low mn map (LM) calculates effects of m=1, n=+1,-1 modes on trajectories of field lines. We use LM with amplitude ɛ=6X10-4 (value expected in modern divertor tokamaks) to describe effects of ELMs. With ELMs, last good surface passes through x=0, y=0.98375. We use dipole map (DM) to represent effects of C-coils. We apply DM after each iteration of SSM. We use s=1.0021, x_dipole=1.5617, y_dipole= 0 for DIII-D shot 115467 [1]. We study changes in the last good surface and its destruction as function of I_C-coil with fixed ɛ = 6X10-4. This work is supported by NASA SHARP program and DE-FG02-02ER54673. [1] H. Ali, A. Punjabi, A. Boozer, and T. Evans, 31st EPS Plasma Phys Mtg, London, UK, June 29, 2004, paper P2-172.

Progress on Pre-Stage Magnetic Coil to Enhance Helicon Mode Excitation and Data Acquisition Software on the Helicon Plasma Experiment (HPX)

NASA Astrophysics Data System (ADS)

Sherman, Justin; Azzari, Phillip; Crilly, P. B.; Duke-Tinson, Omar; James, Royce W.; Karama, Jackson; Page, E. J.; Schlank, Carter; Zuniga, Jonathan

2014-10-01

CGAPL is conducting small investigations in plasma physics and magneto-hydrodynamics buoy positioning. For data management, we are developing capability to analyze/digitize data with a National Instruments Data Acquisition board, 2 MS/s sampling rate (long time scale), and an Express Octopus card, 125 MS/s sampling rate (short scale). Sampling at 12 bits precision, we use LabVIEW as a programing language; GUIs will control variables in 1 or more concurrent runs and monitor of diagnostics. HPX utilizes high density (1013 cm3 up), low pressure (.01 T) Ar gas (fill pressure: on 104 mTorr order). Helicon/W Mode plasmas become a diagnostics test-bed for other investigations and a tool for future spacecraft propulsion devices. Plasmas created by directing energy into gas-filled Pyrex tube; power supply and matching box, up to 250 W power in 20-100 MHz frequencies, provide energy to ignite. Uniform magnetic field needed to reach the W-Mode. We employ an electromagnet to B-field while an acceleration coil positions plasma in vacuum chamber, facilitating analysis. Initial field requirements and accuracy calibration have been completed. Progress on development and implementation of probes and DAQ/GUI system will be reported. Supported by U.S. DEPS Grant [HEL-JTO] PRWJFY13.

Commercial grade item (CGI) dedication of MDR relays for nuclear safety related applications

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

Das, R.K.; Julka, A.; Modi, G.

1994-08-01

MDR relays manufactured by Potter and Brumfield (P and B) have been used in various safety related applications in commercial nuclear power plants. These include emergency safety features (ESF) actuation systems, emergency core cooling systems (ECCS) actuation, and reactor protection systems. The MDR relays manufactured prior to May 1990 showed signs of generic failure due to corrosion and outgassing of coil varnish. P and B has made design changes to correct these problems in relays manufactured after May 1990. However, P and B does not manufacture the relays under any 10CFR50 Appendix B quality assurance (QA) program. They manufacture themore » relays under their commercial QA program and supply these as commercial grade items. This necessitates CGI Dedication of these relays for use in nuclear-safety-related applications. This paper presents a CGI dedication program that has been used to dedicate the MDR relays manufactured after May 1990. The program is in compliance with current Nuclear Regulatory Commission (NRC) and Electric Power Research Institute (EPRI) guidelines and applicable industry standards; it specifies the critical characteristics of the relays, provides the tests and analysis required to verify the critical characteristics, the acceptance criteria for the test results, performs source verification to qualify P and B for its control of the critical characteristics, and provides documentation. The program provides reasonable assurance that the new MDR relays will perform their intended safety functions.« less

The MQXA quadrupoles for the LHC low-beta insertions

NASA Astrophysics Data System (ADS)

Ajima, Y.; Higashi, N.; Iida, M.; Kimura, N.; Nakamoto, T.; Ogitsu, T.; Ohhata, H.; Ohuchi, N.; Shintomi, T.; Sugawara, S.; Sugita, K.; Tanaka, K.; Taylor, T.; Terashima, A.; Tsuchiya, K.; Yamamoto, A.

2005-09-01

High-performance superconducting quadrupole magnets, MQXA, for the LHC low-beta insertions have been designed, manufactured in series and tested. The design field gradient of the quadrupole, which has a coil aperture of diameter 70 mm, was 240 T/m at 1.9 K; its effective length is 6.37 m, and it is required to operate reliably at up to 215 T/m when subjected to radiation heat deposit in the coils of up to 5 W/m. The series of 20 magnets has been produced in industry, and tested at KEK. The magnet design is explained, and the construction and performance of the series units, in terms of training, field quality and geometry, are presented.

Coil-free active stabilisation of extended payloads with optical inertial sensors

NASA Astrophysics Data System (ADS)

Watchi, J.; Ding, B.; Tshilumba, D.; Artoos, K.; Collette, C.

2018-05-01

This paper presents a new active isolation strategy and system which is dedicated to extended payloads, and compatible with the particle accelerator environment. In comparison to the current isolation systems used in this environment, the system proposed does not contain any coil or elastomer, and the supporting frame is dedicated to isolating long payloads from seismic motion. The concept proposed has been tested numerically on 3 and 6 degrees of freedom (DOF) models, and validated experimentally on a 1-DOF scaled test set-up. An attenuation of 40 dB at 1 Hz has been reached with the stage built. The complete description of performance and a noise budgeting are included in this paper.

An Update on Structural Seal Development at NASA GRC

NASA Technical Reports Server (NTRS)

Dunlap, Pat; Steinetz, Bruce; Finkbeiner, Josh; DeMange, Jeff; Taylor, Shawn; Daniels, Chris; Oswald, Jay

2006-01-01

A viewgraph presentation describing advanced structural seal development for NASA exploration is shown. The topics include: 1) GRC Structural Seals Team Research Areas; 2) Research Areas & Objective; 3) Wafer Seal Geometry/Flow Investigations; 4) Wafer Seal Installation DOE Study; 5) Results of Wafer Seal Installation DOE Study; 6) Wafer Geometry Study: Thickness Variations; 7) Wafer Geometry Study: Full-Size vs. Half-Size Wafers; 8) Spring Tube Seal Development; 9) Resiliency Improvement for Rene 41 Spring Tube; 10) Spring Tube Seals: Go-Forward Plan; 11) High Temperature Seal Preloader Development: TZM Canted Coil Spring; 12) TZM Canted Coil Spring Development; 13) Arc Jet Test Rig Development; and 14) Arc Jet Test Rig Status.

Magnetic field transfer device and method

DOEpatents

Wipf, S.L.

1990-02-13

A magnetic field transfer device includes a pair of oppositely wound inner coils which each include at least one winding around an inner coil axis, and an outer coil which includes at least one winding around an outer coil axis. The windings may be formed of superconductors. The axes of the two inner coils are parallel and laterally spaced from each other so that the inner coils are positioned in side-by-side relation. The outer coil is outwardly positioned from the inner coils and rotatable relative to the inner coils about a rotational axis substantially perpendicular to the inner coil axes to generate a hypothetical surface which substantially encloses the inner coils. The outer coil rotates relative to the inner coils between a first position in which the outer coil axis is substantially parallel to the inner coil axes and the outer coil augments the magnetic field formed in one of the inner coils, and a second position 180[degree] from the first position, in which the augmented magnetic field is transferred into the other inner coil and reoriented 180[degree] from the original magnetic field. The magnetic field transfer device allows a magnetic field to be transferred between volumes with negligible work being required to rotate the outer coil with respect to the inner coils. 16 figs.

Magnetic field transfer device and method

DOEpatents

Wipf, Stefan L.

1990-01-01

A magnetic field transfer device includes a pair of oppositely wound inner coils which each include at least one winding around an inner coil axis, and an outer coil which includes at least one winding around an outer coil axis. The windings may be formed of superconductors. The axes of the two inner coils are parallel and laterally spaced from each other so that the inner coils are positioned in side-by-side relation. The outer coil is outwardly positioned from the inner coils and rotatable relative to the inner coils about a rotational axis substantially perpendicular to the inner coil axes to generate a hypothetical surface which substantially encloses the inner coils. The outer coil rotates relative to the inner coils between a first position in which the outer coil axis is substantially parallel to the inner coil axes and the outer coil augments the magnetic field formed in one of the inner coils, and a second position 180.degree. from the first position, in which the augmented magnetic field is transferred into the other inner coil and reoriented 180.degree. from the original magnetic field. The magnetic field transfer device allows a magnetic field to be transferred between volumes with negligible work being required to rotate the outer coil with respect to the inner coils.

The design of a breadboard cryogenic optical delay line for DARWIN

NASA Astrophysics Data System (ADS)

van den Dool, Teun; Kamphues, Fred; Fouss, B.; Henrioulle, K.; Kooijman, P. P.; Visser, Martijn; Velsink, G.; Fleury, K.

2004-09-01

TNO TPD, in cooperation with Micromega-Dynamics, SRON, Dutch Space and CSL, has designed a compact breadboard cryogenic delay line for use in future space interferometry missions. The work is performed under ESA contract in preparation for the DARWIN mission. The breadboard (BB) delay line is representative of a future flight mechanism, with all materials and processes used being flight representative. The delay line has a single stage voice coil actuator for Optical Path Difference (OPD) control, driving a two-mirror cat"s eye. Magnetic bearings provide frictionless and wear free operation with zero-hysteresis. Overall power consumption is below the ESA specification of 2.5 W. The power dissipated on the optical bench at 40 K is considerably less than the maximum allowable 25 mW. The BB delay line will be built in the second half of 2004. The manufacturing and assembly phase is followed by a comprehensive test program, including functional testing at 40 K in 2005. The tests will be carried out by Alcatel Space and SAGEIS-CSO.

Rail-car impact tests with steel coil : car crush

DOT National Transportation Integrated Search

2003-04-22

Two grade-crossing impact tests were conducted in June 2002 at the Federal Railroad Administration's (FRA's) Transportation Technology Center in Pueblo, Colorado as part of the FRA's research into passenger equipment crashworthiness. In both of these...

In vitro assessment of the immunity of implantable cardioverter-defibrillators to magnetic fields of 50/60 Hz.

PubMed

Katrib, J; Nadi, M; Kourtiche, D; Magne, I; Schmitt, P; Souques, M; Roth, P

2013-10-01

Public concern for the compatibility of electromagnetic (EM) sources with active implantable medical devices (AIMD) has prompted the development of new systems that can perform accurate exposure studies. EM field interference with active cardiac implants (e.g. implantable cardioverter-defibrillators (ICDs)) can be critical. This paper describes a magnetic field (MF) exposure system and the method developed for testing the immunity of ICD to continuous-wave MFs. The MFs were created by Helmholtz coils, housed in a Faraday cage. The coils were able to produce highly uniform MFs up to 4000 µT at 50 Hz and 3900 µT at 60 Hz, within the test space. Four ICDs were tested. No dysfunctions were found in the generated MFs. These results confirm that the tested ICDs were immune to low frequency MFs.

Device for precision measurement of speed of sound in a gas

DOEpatents

Kelner, Eric; Minachi, Ali; Owen, Thomas E.; Burzynski, Jr., Marion; Petullo, Steven P.

2004-11-30

A sensor for measuring the speed of sound in a gas. The sensor has a helical coil, through which the gas flows before entering an inner chamber. Flow through the coil brings the gas into thermal equilibrium with the test chamber body. After the gas enters the chamber, a transducer produces an ultrasonic pulse, which is reflected from each of two faces of a target. The time difference between the two reflected signals is used to determine the speed of sound in the gas.

JPRS Report, Science & Technology, Japan, SOR Technology Update

DTIC Science & Technology

1990-12-18

GUN Electron gun c3 GV Gate valve R- ± HL Helmholtz coil IG Ion vacuum gauge IP Ion pump KFC Klystron focusing coil KLY Klystron PB Pre-buncher Q...Therefore, we started studying the manufacture of this kind of film. Recently, such films have been placed on the market as test samples by some foreign... Mixing of sputtered particles from the two targets can also be prevented by making the structure of the bulkhead in the sputtering chamber most

Flight Test Evaluation of Airborne Tire Pressure Indicating Systems.

DTIC Science & Technology

1979-09-01

System (Concept J, Part I Report) This system employs a wheel This system was the best mounted pressure switch the thought out and implemented state of...which is detected across system of its type with an air gap by a rotating coil excellent electror.ic and passing by a statiorery coil pressure switch designs...Pressure Low tire pressure is sensed by a The supplier of this pressure switch in wheel. hardware built a four wheel Pressure switch shorts secondary

Demonstration of Airborne Electromagnetic Systems for Detection and Characterization of Unexploded Ordnance at the Badlands Bombing Range, South Dakota. Revision 3

DTIC Science & Technology

2004-08-01

base station Attitude Measurement Ashtech ADU-2 Bartington MAG03ML7ONT 3-axis fluxgate magnetometer , Navigation Picodas PNAV100 Model P141-E Real...BBR Test Grid, horizontal difference (outer coil minus scaled inner coil). 46 22 Analytic signal derived from ground-based magnetometer bottom...one meter over UXO-contaminated terrain. As with the magnetic systems, GPS and laser altimetry provide precise positioning to within a few tens of

MR-Guided Near Infrared Spectroscopy for Reducing Breast Cancer False Positives

DTIC Science & Technology

2009-09-01

an Invivo breast coil in a (b) Philips scanner , and (b) a USA Instruments coil in a (d) GE scanner . 8 Quantitative accuracy in optical imaging...reconstruction [7], which includes a weighting term to account for the accuracy of the MR scanner in determining water and fat images. The advantage of... scanner used in this study. These methods were tested in a 86mm diameter gelatin phantom, shown in Figure 6, with porcine blood added to mimic the

Lambda Probe Measurements of Laboratory Spheromaks

NASA Astrophysics Data System (ADS)

Jorne, E.; Bellan, P. M.; Hsu, S. C.; Moynihan, C.

2003-10-01

A combined current and magnetic probe (lambda probe) has been constructed and is being tested for the purpose of investigating the behavior of spheromaks formed by the Caltech planar spheromak gun. The probe consists of a 1.5cm diameter, 52 turn Rogowski coil and a single loop magnetic coil, housed in a ceramic shell attached to a 95cm long hollow, steel shaft. A high voltage power supply was used to test the probe's ability to measure pulsed currents with submicrosecond rise times. A calibrated current pulse was provided by a 1μF capacitor discharged by a krytron switch to a low inductance circuit. Magnetic calibration was obtained by using the capacitor bank to power a 16cm diameter Helmholtz coil. Both magnetic and current calibration were in good agreement with estimates based on geometry. An existing steel shaft will be replaced by a ceramic shaft in order to minimize undesired effects on the plasma by a conductor. Once sealed with epoxy, the probe will be ready for insertion into the vacuum chamber and used to measure the magnetic field and parallel current during spheromak formation.

Solid cryogen: a cooling system for future MgB2 MRI magnet.

PubMed

Patel, Dipak; Hossain, Md Shahriar Al; Qiu, Wenbin; Jie, Hyunseock; Yamauchi, Yusuke; Maeda, Minoru; Tomsic, Mike; Choi, Seyong; Kim, Jung Ho

2017-03-02

An efficient cooling system and the superconducting magnet are essential components of magnetic resonance imaging (MRI) technology. Herein, we report a solid nitrogen (SN 2 ) cooling system as a valuable cryogenic feature, which is targeted for easy usability and stable operation under unreliable power source conditions, in conjunction with a magnesium diboride (MgB 2 ) superconducting magnet. The rationally designed MgB 2 /SN 2 cooling system was first considered by conducting a finite element analysis simulation, and then a demonstrator coil was empirically tested under the same conditions. In the SN 2 cooling system design, a wide temperature distribution on the SN 2 chamber was observed due to the low thermal conductivity of the stainless steel components. To overcome this temperature distribution, a copper flange was introduced to enhance the temperature uniformity of the SN 2 chamber. In the coil testing, an operating current as high as 200 A was applied at 28 K (below the critical current) without any operating or thermal issues. This work was performed to further the development of SN 2 cooled MgB 2 superconducting coils for MRI applications.

Solid cryogen: a cooling system for future MgB2 MRI magnet

NASA Astrophysics Data System (ADS)

Patel, Dipak; Hossain, Md Shahriar Al; Qiu, Wenbin; Jie, Hyunseock; Yamauchi, Yusuke; Maeda, Minoru; Tomsic, Mike; Choi, Seyong; Kim, Jung Ho

2017-03-01

An efficient cooling system and the superconducting magnet are essential components of magnetic resonance imaging (MRI) technology. Herein, we report a solid nitrogen (SN2) cooling system as a valuable cryogenic feature, which is targeted for easy usability and stable operation under unreliable power source conditions, in conjunction with a magnesium diboride (MgB2) superconducting magnet. The rationally designed MgB2/SN2 cooling system was first considered by conducting a finite element analysis simulation, and then a demonstrator coil was empirically tested under the same conditions. In the SN2 cooling system design, a wide temperature distribution on the SN2 chamber was observed due to the low thermal conductivity of the stainless steel components. To overcome this temperature distribution, a copper flange was introduced to enhance the temperature uniformity of the SN2 chamber. In the coil testing, an operating current as high as 200 A was applied at 28 K (below the critical current) without any operating or thermal issues. This work was performed to further the development of SN2 cooled MgB2 superconducting coils for MRI applications.

Development of superconducting magnetic bearing using superconducting coil and bulk superconductor

NASA Astrophysics Data System (ADS)

Seino, H.; Nagashima, K.; Arai, Y.

2008-02-01

The authors conducted a study on superconducting magnetic bearing, which consists of superconducting rotor and stator to apply the flywheel energy-storage system for railways. In this study, high temperature bulk superconductor (HTS bulk) was combined with superconducting coils to increase the load capacity of the bearing. In the first step of the study, the thrust rolling bearing was selected for application by using liquid nitrogen cooled HTS bulk. 60mm-diameter HTS bulks and superconducting coil which generated a high gradient of magnetic field by cusp field were adopted as a rotor and a stator for superconducting magnetic bearing, respectively. The results of the static load test and the rotation test, creep of the electromagnetic forces caused by static flux penetration and AC loss due to eccentric rotation were decreased to the level without any problems in substantial use by using two HTS bulks. In the result of verification of static load capacity, levitation force (thrust load) of 8900N or more was supportable, and stable static load capacity was obtainable when weight of 460kg was levitated.

Conformational switching in the coiled-coil domains of a proteasomal ATPase regulates substrate processing.

PubMed

Snoberger, Aaron; Brettrager, Evan J; Smith, David M

2018-06-18

Protein degradation in all domains of life requires ATPases that unfold and inject proteins into compartmentalized proteolytic chambers. Proteasomal ATPases in eukaryotes and archaea contain poorly understood N-terminally conserved coiled-coil domains. In this study, we engineer disulfide crosslinks in the coiled-coils of the archaeal proteasomal ATPase (PAN) and report that its three identical coiled-coil domains can adopt three different conformations: (1) in-register and zipped, (2) in-register and partially unzipped, and (3) out-of-register. This conformational heterogeneity conflicts with PAN's symmetrical OB-coiled-coil crystal structure but resembles the conformational heterogeneity of the 26S proteasomal ATPases' coiled-coils. Furthermore, we find that one coiled-coil can be conformationally constrained even while unfolding substrates, and conformational changes in two of the coiled-coils regulate PAN switching between resting and active states. This switching functionally mimics similar states proposed for the 26S proteasome from cryo-EM. These findings thus build a mechanistic framework to understand regulation of proteasome activity.

RF HEATING OF MRI-ASSISTED CATHETER STEERING COILS FOR INTERVENTIONAL MRI

PubMed Central

Settecase, Fabio; Hetts, Steven W.; Martin, Alastair J.; Roberts, Timothy P. L.; Bernhardt, Anthony F.; Evans, Lee; Malba, Vincent; Saeed, Maythem; Arenson, Ronald L.; Kucharzyk, Walter; Wilson, Mark W.

2010-01-01

RATIONALE AND OBJECTIVES To assess magnetic resonance imaging (MRI) radiofrequency (RF) related heating of conductive wire coils used in magnetically steerable endovascular catheters. MATERIALS AND METHODS A 3-axis microcoil was fabricated onto a 1.8 Fr catheter tip. In vitro testing was performed in a 1.5 T MRI system using an agarose gel filled vessel phantom, a transmit/receive body RF coil and a steady state free precession (SSFP) pulse sequence, and a fluoroptic thermometry system. Temperature was measured without simulated blood flow at varying distances from magnet isocenter and varying flip angles. Additional experiments were performed with laser-lithographed single-axis microcoil-tipped microcatheters in air and in a saline bath with varied grounding of the microcoil wires. Preliminary in vivo evaluation of RF heating was performed in pigs at 1.5 T with coil-tipped catheters in various positions in the common carotid arteries with SSFP pulse sequence on and off, and under physiologic flow and zero flow conditions. RESULTS In tissue-mimicking agarose gel, RF heating resulted in a maximal temperature increase of 0.35°C after 15 minutes of imaging, 15 cm from magnet isocenter. For a single axis microcoil, maximal temperature increases were 0.73-1.91°C in air and 0.45-0.55°C in saline. In vivo, delayed contrast enhanced MRI revealed no evidence of vascular injury and histopathological sections from the common carotid arteries confirmed the lack of vascular damage. CONCLUSIONS Microcatheter tip microcoils for endovascular catheter steering in MRI experience minimal RF heating under the conditions tested. These data provide the basis for further in vivo testing of this promising technology for endovascular interventional MRI. PMID:21075019

A superconducting homopolar motor and generator—new approaches

NASA Astrophysics Data System (ADS)

Fuger, Rene; Matsekh, Arkadiy; Kells, John; Sercombe, D. B. T.; Guina, Ante

2016-03-01

Homopolar machines were the first continuously running electromechanical converters ever demonstrated but engineering challenges and the rapid development of AC technology prevented wider commercialisation. Recent developments in superconducting, cryogenic and sliding contact technology together with new areas of application have led to a renewed interest in homopolar machines. Some of the advantages of these machines are ripple free constant torque, pure DC operation, high power-to-weight ratio and that rotating magnets or coils are not required. In this paper we present our unique approach to high power and high torque homopolar electromagnetic turbines using specially designed high field superconducting magnets and liquid metal current collectors. The unique arrangement of the superconducting coils delivers a high static drive field as well as effective shielding for the field critical sliding contacts. The novel use of additional shielding coils reduces weight and stray field of the system. Liquid metal current collectors deliver a low resistance, stable and low maintenance sliding contact by using a thin liquid metal layer that fills a circular channel formed by the moving edge of a rotor and surrounded by a conforming stationary channel of the stator. Both technologies are critical to constructing high performance machines. Homopolar machines are pure DC devices that utilise only DC electric and magnetic fields and have no AC losses in the coils or the supporting structure. Guina Energy Technologies has developed, built and tested different motor and generator concepts over the last few years and has combined its experience to develop a new generation of homopolar electromagnetic turbines. This paper summarises the development process, general design parameters and first test results of our high temperature superconducting test motor.

Molecular basis of coiled-coil oligomerization-state specificity.

PubMed

Ciani, Barbara; Bjelic, Saša; Honnappa, Srinivas; Jawhari, Hatim; Jaussi, Rolf; Payapilly, Aishwarya; Jowitt, Thomas; Steinmetz, Michel O; Kammerer, Richard A

2010-11-16

Coiled coils are extensively and successfully used nowadays to rationally design multistranded structures for applications, including basic research, biotechnology, nanotechnology, materials science, and medicine. The wide range of applications as well as the important functions these structures play in almost all biological processes highlight the need for a detailed understanding of the factors that control coiled-coil folding and oligomerization. Here, we address the important and unresolved question why the presence of particular oligomerization-state determinants within a coiled coil does frequently not correlate with its topology. We found an unexpected, general link between coiled-coil oligomerization-state specificity and trigger sequences, elements that are indispensable for coiled-coil formation. By using the archetype coiled-coil domain of the yeast transcriptional activator GCN4 as a model system, we show that well-established trimer-specific oligomerization-state determinants switch the peptide's topology from a dimer to a trimer only when inserted into the trigger sequence. We successfully confirmed our results in two other, unrelated coiled-coil dimers, ATF1 and cortexillin-1. We furthermore show that multiple topology determinants can coexist in the same trigger sequence, revealing a delicate balance of the resulting oligomerization state by position-dependent forces. Our experimental results should significantly improve the prediction of the oligomerization state of coiled coils. They therefore should have major implications for the rational design of coiled coils and consequently many applications using these popular oligomerization domains.

Testing of a First Order AC Magnetic Susceptometer

NASA Astrophysics Data System (ADS)

Fukuda, Ryan; Sunny, Smitha; Ho, Pei-Chun

2011-11-01

A first-order AC magnetic susceptometer has been constructed and tested to find the magnetic response of strongly correlated electron materials. The instrument works by using a primary coil to apply a small AC magnetic field of .104 Oe to a sample with a cylindrical coil space of length .635 cm and diameter .355 cm. A lock-in amplifier is used to monitor the induced voltage from a set of secondary coils. By coupling a temperature-controlled system with this instrument, the change in the magnetic signal with respect to temperature is measured. Monitoring the signal changes may indicate the temperature that causes the material to transition to either a ferromagnetic, anti-ferromagnetic, or superconducting state. A 122.47 mg Gd polycrystal was used to test our susceptometer. The data qualitatively agrees with the previous results of magnetization vs. temperature of Gd single crystals by Nigh et al. [1]: there is a steep increase in the pick-up signal at 300 K where Gd becomes ferromagnetic and a peak at 210 K [1]. This susceptometer will be used for our future investigation of magnetic properties of rare earth compounds and nanoparticles in the temperature range of 10 K to 300 K. [4pt] [1] H. E. Nigh, S. Legvold, and F. H. Spedding, Physical Review 132, 1092 (1963)

Fabrication, Testing and Modeling of the MICE Superconducting Spectrometer Solenoids

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

Virostek, S.P.; Green, M.A.; Trillaud, F.

2010-05-16

The Muon Ionization Cooling Experiment (MICE), an international collaboration sited at Rutherford Appleton Laboratory in the UK, will demonstrate ionization cooling in a section of realistic cooling channel using a muon beam. A five-coil superconducting spectrometer solenoid magnet will provide a 4 tesla uniform field region at each end of the cooling channel. Scintillating fiber trackers within the 400 mm diameter magnet bore tubes measure the emittance of the beam as it enters and exits the cooling channel. Each of the identical 3-meter long magnets incorporates a three-coil spectrometer magnet section and a two-coil section to match the solenoid uniformmore » field into the other magnets of the MICE cooling channel. The cold mass, radiation shield and leads are currently kept cold by means of three two-stage cryocoolers and one single-stage cryocooler. Liquid helium within the cold mass is maintained by means of a re-condensation technique. After incorporating several design changes to improve the magnet cooling and reliability, the fabrication and acceptance testing of the spectrometer solenoids have proceeded. The key features of the spectrometer solenoid magnets, the development of a thermal model, the results of the recently completed tests, and the current status of the project are presented.« less

Assessment of conductor degradation in the ITER CS insert coil and implications for the ITER conductors

NASA Astrophysics Data System (ADS)

Mitchell, N.

2007-01-01

Nb3Sn cable in conduit-type conductors were expected to provide an efficient way of achieving large conductor currents at high field (up to 13 T) combined with good stability to electromagnetic disturbances due to the extensive helium contact area with the strands. Although ITER model coils successfully reached their design performance (Kato et al 2001 Fusion Eng. Des. 56/57 59-70), initial indications (Mitchell 2003 Fusion Eng. Des. 66-68 971-94) that there were unexplained performance shortfalls have been confirmed. Recent conductor tests (Pasztor et al 2004 IEEE Trans. Appl. Supercond. 14 1527-30) and modelling work (Mitchell 2005 Supercond. Sci. Technol. 18 396-404) suggest that the shortfalls are due to a combination of strand bending and filament fracture under the transverse magnetic loads. Using the new model, the extensive database from the ITER CS insert coil has been reassessed. A parametric fit based on a loss of filament area and n (the exponent of the power-law fit to the electric field) combined with a more rigorous consideration of the conductor field gradient has enabled the coil behaviour to be explained much more consistently than in earlier assessments, now fitting the Nb3Sn strain scaling laws when used with measurements of the conductor operating strain, including conditions when the insert coil current (and hence operating strain) were reversed. The coil superconducting performance also shows a fatigue-type behaviour consistent with recent measurements on conductor samples (Martovetsky et al 2005 IEEE Trans. Appl. Supercond. 15 1367-70). The ITER conductor design has already been modified compared to the CS insert, to increase the margin and provide increased resistance to the degradation, by using a steel jacket to provide thermal pre-compression to reduce tensile strain levels, reducing the void fraction from 36% to 33% and increasing the non-copper material by 25%. Test results are not yet available for the new design and performance predictions at present rely on models with limited verification.

Design study of superconducting magnets for a combustion magnetohydrodynamic /MHD/ generator

NASA Technical Reports Server (NTRS)

Thome, R. J.; Ayers, J. W.; Hrycaj, T. M.; Burkhart, J. A.

1978-01-01

Results are presented for a trade-off and preliminary design study on concepts of a superconducting magnet system for a combustion MHD generator test facility. The main objective is to gain insight into the magnitude of the project in terms of physical characteristics and cost. The net result of a first-phase evaluation of attractive design alternatives is to concentrate subsequent efforts on (1) a racetrack coil geometry with an operating temperature of 4.2 K, (2) a racetrack coil geometry with an operating temperature of 2.0 K, and (3) a rectangular saddle coil geometry with an operating temperature of 4.2 K. All three systems are to produce 8 T, and use NbTi superconductor and iron for field enhancement. Design characteristics of the three systems are described. It is shown that the racetrack and rectangular saddle coil geometries seem most suitable for this application, the former because of its simplicity and the latter because of its efficient use of material. Advantages of the rectangular saddle over the two other systems are stressed.

Symptomatic delayed coil migration after balloon assisted embolization: An underreported adverse event?

PubMed

Fonseca, Lino; Najarro-Quispe, Rafael; Rodríguez-Hernández, Ana; Torné, Ramon; Gándara-Sabatini, Dario; Arikan, Fuat; Baños-Carrasco, Pilar

2018-04-03

Microsurgical clipping is still regarded as the gold-standard treatment for broad-neck intracranial aneurysms. New endovascular techniques like balloon or stent assisted coiling are quickly rising to the challenge and showing promising outcomes. As a result, broad-neck aneurysms are increasingly addressed by these techniques despite they have not been tested against clipping in a randomized controlled trial and long-term complications might be unknown yet. Intraprocedural coil migration has been well documented in the literature, but the same complication in a delayed fashion is scarcely reported. We present a case of delayed coil migration occurring after a balloon-assisted embolization of a wide-necked intracranial aneurysm and we perform a literature review for similar cases. We discuss how, despite seeming an extremely rare complication, with new endovascular techniques increasingly perceived as the safer option in any aneurysm, potential adverse events may become more frequent. Strategies proposed to address this developing scenario are also reviewed. Copyright © 2018 Sociedad Española de Neurocirugía. Publicado por Elsevier España, S.L.U. All rights reserved.

Getting a grip on the transverse motion in a Zeeman decelerator

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

Dulitz, Katrin; Softley, Timothy P., E-mail: tim.softley@chem.ox.ac.uk; Motsch, Michael

2014-03-14

Zeeman deceleration is an experimental technique in which inhomogeneous, time-dependent magnetic fields generated inside an array of solenoid coils are used to manipulate the velocity of a supersonic beam. A 12-stage Zeeman decelerator has been built and characterized using hydrogen atoms as a test system. The instrument has several original features including the possibility to replace each deceleration coil individually. In this article, we give a detailed description of the experimental setup, and illustrate its performance. We demonstrate that the overall acceptance in a Zeeman decelerator can be significantly increased with only minor changes to the setup itself. This ismore » achieved by applying a rather low, anti-parallel magnetic field in one of the solenoid coils that forms a temporally varying quadrupole field, and improves particle confinement in the transverse direction. The results are reproduced by three-dimensional numerical particle trajectory simulations thus allowing for a rigorous analysis of the experimental data. The findings suggest the use of a modified coil configuration to improve transverse focusing during the deceleration process.« less

Design development and construction of the RFX field shaping winding

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

Chitarin, G.; Guarnieri, M.; Stella, A.

1989-03-01

The paper describes the development work on the design and the manufacture of the RFX Field Shaping Winding, from the preliminary analysis and the tests on prototypes to the final design. The winding consists of 16 coils, with 24 copper turns each and of diameters up to 5.5 m. The maximum current is 6.25 kA and the maximum voltage to earth is 35 kV. Each coil is supported in 24 radial locations and the electrodynamic load on a single coil is approximately 40 kN/m in normal operation. Fiberglass impregnated with epoxy resin, reinforced in places with polymide tape, has beenmore » used for the insulation. The high levels of the electrical and mechanical strength specified present conflicting constraints, which have required some care in the structural design and the definition of insulation system and impregnation technology. Although the use of copper coils with this kid of insulation may seem obvious and well established, indeed the stringent operational requirements have posed a number of problems which have demanded extensive work on the design and prototype development.« less

Progress Toward Attractive Stellarators

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

Neilson, G H; Brown, T G; Gates, D A

The quasi-axisymmetric stellarator (QAS) concept offers a promising path to a more compact stellarator reactor, closer in linear dimensions to tokamak reactors than previous stellarator designs. Concept improvements are needed, however, to make it more maintainable and more compatible with high plant availability. Using the ARIES-CS design as a starting point, compact stellarator designs with improved maintenance characteristics have been developed. While the ARIES-CS features a through-the-port maintenance scheme, we have investigated configuration changes to enable a sector-maintenance approach, as envisioned for example in ARIES AT. Three approaches are reported. The first is to make tradeoffs within the QAS designmore » space, giving greater emphasis to maintainability criteria. The second approach is to improve the optimization tools to more accurately and efficiently target the physics properties of importance. The third is to employ a hybrid coil topology, so that the plasma shaping functions of the main coils are shared more optimally, either with passive conductors made of high-temperature superconductor or with local compensation coils, allowing the main coils to become simpler. Optimization tools are being improved to test these approaches.« less

MR-compatibility assessment of MADPET4: a study of interferences between an SiPM-based PET insert and a 7 T MRI system

NASA Astrophysics Data System (ADS)

Omidvari, Negar; Topping, Geoffrey; Cabello, Jorge; Paul, Stephan; Schwaiger, Markus; Ziegler, Sibylle I.

2018-05-01

Compromises in the design of a positron emission tomography (PET) insert for a magnetic resonance imaging (MRI) system should minimize the deterioration of image quality in both modalities, particularly when simultaneous demanding acquisitions are performed. In this work, the advantages of using individually read-out crystals with high-gain silicon photomultipliers (SiPMs) were studied with a small animal PET insert for a 7 T MRI system, in which the SiPM charge was transferred to outside the MRI scanner using coaxial cables. The interferences between the two systems were studied with three radio-frequency (RF) coil configurations. The effects of PET on the static magnetic field, flip angle distribution, RF noise, and image quality of various MRI sequences (gradient echo, spin echo, and echo planar imaging (EPI) at 1H frequency, and chemical shift imaging at 13C frequency) were investigated. The effects of fast-switching gradient fields and RF pulses on PET count rate were studied, while the PET insert and the readout electronics were not shielded. Operating the insert inside a 1H volume coil, used for RF transmission and reception, limited the MRI to T1-weighted imaging, due to coil detuning and RF attenuation, and resulted in significant PET count loss. Using a surface receive coil allowed all tested MR sequences to be used with the insert, with 45–59% signal-to-noise ratio (SNR) degradation, compared to without PET. With a 1H/13C volume coil inside the insert and shielded by a copper tube, the SNR degradation was limited to 23–30% with all tested sequences. The insert did not introduce any discernible distortions into images of two tested EPI sequences. Use of truncated sinc shaped RF excitation pulses and gradient field switching had negligible effects on PET count rate. However, PET count rate was substantially affected by high-power RF block pulses and temperature variations due to high gradient duty cycles.

Integrated induction coil and fluxgate magnetometers for EM analysis and monitoring

NASA Astrophysics Data System (ADS)

Hanstein, T.; Strack, K.; Jiang, J.

2013-12-01

The concept of a full field array electromagnetic system is an ideal tool to support hydrocarbon and geothermal E & P as well as various engineering monitoring applications. Some of the key questions are defining the reservoir, mapping of the fractures and reservoir depletion monitoring. The reservoirs are all too often relative thin and give an anomalous electromagnetic (EM) response, which is often small in amplitude and challenging for the EM measuring system. A digital fluxgate magnetometer (32-bit) is connected to the KMS magnetotelluric acquisition system with analogue induction coils and electrodes to extend the range of application of a single recording site. Since the noise level is above that of the induction coil for periods shorter than 20 s, the apparent resistivity is biased. For longer periods the apparent resistivity is consistent and eventually better than the induction coil. However, phase and tipper are not biased and agree well with the induction data even for shorter periods. This allows us to develop algorithms that significantly extend the range of application of the fluxgate beyond what was done in the past. The highest frequency of the fluxgate magnetometer is about 180 Hz and the hightest sampling of the FG-board is 4 kHz.The different induction coils and fluxgate magnetometer have intensively been tested in the magnetic chamber and at the field test site near Houston for noise performance by parallel recordings. They show that even in an environment with high cultural noise, the specification can be met. In Northeast China, a 30-day monitoring test with MT was carried out for seismologic applications. Acquisitition schedule included different recordings times and sampling rates. Daily, the data was collected and processed via the internet from either Europe or the US. Even with long recording, we still had to select the time windows for data averaging and coherences are not a good threshhold criteria in this case. During another MT sounding in India, an earthquake with magnitude 5 at a distance of about 200 km was recorded. The event is very strong in amplitude and visible in all magnetic and electric field components.

A new type of coil structure called pan-shaped coil of wireless charging system based on magnetic resonance

NASA Astrophysics Data System (ADS)

Yue, Z. K.; Liu, Z. Z.; Hou, Y. J.; Zeng, H.; Liang, L. H.; Cui, S.

2017-11-01

The problem that misalignment between the transmitting coil and the receiving coil significantly impairs the transmission power and efficiency of the system has been attached more and more attention. In order to improve the uniformity of the magnetic field between the two coils to solve this problem, a new type of coil called pan-shaped coil is proposed. Three-dimension simulation models of the planar-core coil and the pan-shaped coil are established using Ansoft Maxwell software. The coupling coefficient between the transmitting coil and the receiving coil is obtained by simulating the magnetic field with the receiving coil misalignment or not. And the maximum percentage difference strength along the radial direction which is defined as the magnetic field uniformity factor is calculated. According to the simulation results of the two kinds of coil structures, it is found that the new type of coil structure can obviously improve the uniformity of the magnetic field, coupling coefficient and power transmission properties between the transmitting coil and the receiving coil.

Improvement of wireless power transmission efficiency of implantable subcutaneous devices by closed magnetic circuit mechanism.

PubMed

Jo, Sung-Eun; Joung, Sanghoon; Suh, Jun-Kyo Francis; Kim, Yong-Jun

2012-09-01

Induction coils were fabricated based on flexible printed circuit board for inductive transcutaneous power transmission. The coil had closed magnetic circuit (CMC) structure consisting of inner and outer magnetic core. The power transmission efficiency of the fabricated device was measured in the air and in vivo condition. It was confirmed that the CMC coil had higher transmission efficiency than typical air-core coil. The power transmission efficiency during a misalignment between primary coil and implanted secondary coil was also evaluated. The decrease of mutual inductance between the two coils caused by the misalignment led to a low efficiency of the inductive link. Therefore, it is important to properly align the primary coil and implanted secondary coil for effective power transmission. To align the coils, a feedback coil was proposed. This was integrated on the backside of the primary coil and enabled the detection of a misalignment of the primary and secondary coils. As a result of using the feedback coil, the primary and secondary coils could be aligned without knowledge of the position of the implanted secondary coil.

The structure of the GemC1 coiled coil and its interaction with the Geminin family of coiled-coil proteins

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

Caillat, Christophe; Fish, Alexander; Pefani, Dafni-Eleftheria

The GemC1 coiled-coil structure has subtle differences compared with its homologues Geminin and Idas. Co-expression experiments in cells and biophysical stability analysis of the Geminin-family coiled coils suggest that the GemC1 coiled coil alone is unstable. GemC1, together with Idas and Geminin, an important regulator of DNA-replication licensing and differentiation decisions, constitute a superfamily sharing a homologous central coiled-coil domain. To better understand this family of proteins, the crystal structure of a GemC1 coiled-coil domain variant engineered for better solubility was determined to 2.2 Å resolution. GemC1 shows a less typical coiled coil compared with the Geminin homodimer and themore » Geminin–Idas heterodimer structures. It is also shown that both in vitro and in cells GemC1 interacts with Geminin through its coiled-coil domain, forming a heterodimer that is more stable that the GemC1 homodimer. Comparative analysis of the thermal stability of all of the possible superfamily complexes, using circular dichroism to follow the unfolding of the entire helix of the coiled coil, or intrinsic tryptophan fluorescence of a unique conserved N-terminal tryptophan, shows that the unfolding of the coiled coil is likely to take place from the C-terminus towards the N-terminus. It is also shown that homodimers show a single-state unfolding, while heterodimers show a two-state unfolding, suggesting that the dimer first falls apart and the helices then unfold according to the stability of each protein. The findings argue that Geminin-family members form homodimers and heterodimers between them, and this ability is likely to be important for modulating their function in cycling and differentiating cells.« less

Commissioning and Testing the 1970's Era LASS Solenoid Magnet in JLab's Hall D

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

Ballard, Joshua T.; Biallas, George H.; Brown, G.

2015-06-01

JLab refurbished and reconfigured the LASS1, 1.85m bore Solenoid and installed it as the principal analysis magnet for nuclear physics in the newly constructed, Hall D at Jefferson Lab. The magnet contains four superconducting coils within an iron yoke. The magnet was built in the early1970's at Stanford Linear Accelerator Center and used a second time at Los Alamos National Laboratory. The coils were extensively refurbished and individually tested by JLab. A new Cryogenic Distribution Box provides cryogens and their control valving, current distribution bus, and instrumentation pass-through. A repurposed CTI 2800 refrigerator system and new transfer line complete themore » system. We describe the re-configuration, the process and problems of re-commissioning the magnet and the results of testing the completed magnet.« less

Physical–chemical determinants of coil conformations in globular proteins

PubMed Central

Perskie, Lauren L; Rose, George D

2010-01-01

We present a method with the potential to generate a library of coil segments from first principles. Proteins are built from α-helices and/or β-strands interconnected by these coil segments. Here, we investigate the conformational determinants of short coil segments, with particular emphasis on chain turns. Toward this goal, we extracted a comprehensive set of two-, three-, and four-residue turns from X-ray–elucidated proteins and classified them by conformation. A remarkably small number of unique conformers account for most of this experimentally determined set, whereas remaining members span a large number of rare conformers, many occurring only once in the entire protein database. Factors determining conformation were identified via Metropolis Monte Carlo simulations devised to test the effectiveness of various energy terms. Simulated structures were validated by comparison to experimental counterparts. After filtering rare conformers, we found that 98% of the remaining experimentally determined turn population could be reproduced by applying a hydrogen bond energy term to an exhaustively generated ensemble of clash-free conformers in which no backbone polar group lacks a hydrogen-bond partner. Further, at least 90% of longer coil segments, ranging from 5- to 20 residues, were found to be structural composites of these shorter primitives. These results are pertinent to protein structure prediction, where approaches can be divided into either empirical or ab initio methods. Empirical methods use database-derived information; ab initio methods rely on physical–chemical principles exclusively. Replacing the database-derived coil library with one generated from first principles would transform any empirically based method into its corresponding ab initio homologue. PMID:20512968

Ontogenetic constraints on foraminiferal test construction.

PubMed

Caromel, Aude G M; Schmidt, Daniela N; Rayfield, Emily J

2017-05-01

Developmental processes represent one of the main constraints on the generation of adult form. Determining how constructional and energetic demands operate throughout growth is es-sential to understanding fundamental growth rules and trade-offs that define the framework within which new species originate. In organisms producing spiral shells, coiling patterns can inform on the constructional constraints acting throughout development that dictated the diversification of forms within a group. Here, we use Synchrotron radiation X-Ray tomographic microscopy (SRXTM) reconstructions of eight planktic foraminifera repre-sentative of the major morphotypic groups to determine disparity of coiling patterns by measuring Raupian parameters. The results show that foraminifera are a morphologically highly conservative group, exploiting a limited range of poten-tial coiling patterns. Very similar coiling patterns during early ontogeny, regardless of species, point toward strong constraints in early ontogeny and to common develop-mental processes acting across all morphogroups. Dispersion and lateral displacement of taxa in morphospace are limited to the adult stage. Accretion with low translation down the coiling axis in juveniles may maximize lateral growth and metabolic efficiency in light of costly calcification. Increased translation in the adult stages allows growth to accommo-date new chamber shapes, mediated by changes in aperture location and the site of accretion over ontogeny. These constructional constraints, and the accretion of a small number of discrete chambers, limit the potential for novel forms within the foraminifera compared to other groups of coiling organisms and may explain the repeated evolution of similar morphotypes throughout the evolutionary history of the group. © 2017 Wiley Periodicals, Inc.

A periodic table of coiled-coil protein structures.

PubMed

Moutevelis, Efrosini; Woolfson, Derek N

2009-01-23

Coiled coils are protein structure domains with two or more alpha-helices packed together via interlacing of side chains known as knob-into-hole packing. We analysed and classified a large set of coiled-coil structures using a combination of automated and manual methods. This led to a systematic classification that we termed a "periodic table of coiled coils," which we have made available at http://coiledcoils.chm.bris.ac.uk/ccplus/search/periodic_table. In this table, coiled-coil assemblies are arranged in columns with increasing numbers of alpha-helices and in rows of increased complexity. The table provides a framework for understanding possibilities in and limits on coiled-coil structures and a basis for future prediction, engineering and design studies.

Bullion to B-fields: The Silver Program of the Manhattan Project

NASA Astrophysics Data System (ADS)

Reed, Cameron

2010-04-01

Between October 1942 and September 1944, over 14,000 tons of silver bullion bars withdrawn form the U.S. Treasury were melted and cast into magnet coils and busbar pieces for the ``calutron'' electromagnetic isotope-separators constructed at Oak Ridge. Based on Manhattan Engineer District documents, this paper will review the history of this ``Silver Program,'' including discussions of the contractors, production methods, and quantities of materials involved.

Bullion to B-fields: The Silver Program of the Manhattan Project

NASA Astrophysics Data System (ADS)

Reed, Cameron

2010-02-01

Between October 1942 and September 1944, over 14,000 tons of silver bullion bars withdrawn from the U. S. Treasury were melted and cast into magnet coils and busbar pieces for the ``calutron'' electromagnetic isotope-separators constructed at Oak Ridge. Based on Manhattan Engineer District documents, this paper will review the history of this ``Silver Program,'' including discussions of the contractors, production methods, and quantities of material involved. )

Four signature motifs define the first class of structurally related large coiled-coil proteins in plants.

PubMed Central

Gindullis, Frank; Rose, Annkatrin; Patel, Shalaka; Meier, Iris

2002-01-01

Background Animal and yeast proteins containing long coiled-coil domains are involved in attaching other proteins to the large, solid-state components of the cell. One subgroup of long coiled-coil proteins are the nuclear lamins, which are involved in attaching chromatin to the nuclear envelope and have recently been implicated in inherited human diseases. In contrast to other eukaryotes, long coiled-coil proteins have been barely investigated in plants. Results We have searched the completed Arabidopsis genome and have identified a family of structurally related long coiled-coil proteins. Filament-like plant proteins (FPP) were identified by sequence similarity to a tomato cDNA that encodes a coiled-coil protein which interacts with the nuclear envelope-associated protein, MAF1. The FPP family is defined by four novel unique sequence motifs and by two clusters of long coiled-coil domains separated by a non-coiled-coil linker. All family members are expressed in a variety of Arabidopsis tissues. A homolog sharing the structural features was identified in the monocot rice, indicating conservation among angiosperms. Conclusion Except for myosins, this is the first characterization of a family of long coiled-coil proteins in plants. The tomato homolog of the FPP family binds in a yeast two-hybrid assay to a nuclear envelope-associated protein. This might suggest that FPP family members function in nuclear envelope biology. Because the full Arabidopsis genome does not appear to contain genes for lamins, it is of interest to investigate other long coiled-coil proteins, which might functionally replace lamins in the plant kingdom. PMID:11972898

A new twist in the coil: functions of the coiled-coil domain of structural maintenance of chromosome (SMC) proteins.

PubMed

Matityahu, Avi; Onn, Itay

2018-02-01

The higher-order organization of chromosomes ensures their stability and functionality. However, the molecular mechanism by which higher order structure is established is poorly understood. Dissecting the activity of the relevant proteins provides information essential for achieving a comprehensive understanding of chromosome structure. Proteins of the structural maintenance of chromosome (SMC) family of ATPases are the core of evolutionary conserved complexes. SMC complexes are involved in regulating genome dynamics and in maintaining genome stability. The structure of all SMC proteins resembles an elongated rod that contains a central coiled-coil domain, a common protein structural motif in which two α-helices twist together. In recent years, the imperative role of the coiled-coil domain to SMC protein activity and regulation has become evident. Here, we discuss recent advances in the function of the SMC coiled coils. We describe the structure of the coiled-coil domain of SMC proteins, modifications and interactions that are mediated by it. Furthermore, we assess the role of the coiled-coil domain in conformational switches of SMC proteins, and in determining the architecture of the SMC dimer. Finally, we review the interplay between mutations in the coiled-coil domain and human disorders. We suggest that distinctive properties of coiled coils of different SMC proteins contribute to their distinct functions. The discussion clarifies the mechanisms underlying the activity of SMC proteins, and advocates future studies to elucidate the function of the SMC coiled coil domain.

Vacuum Studies of a Prototype Composite Coil Dewar for HTSC Transformers

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

Schwenterly, S W; Zhang, Y.; Pleva, Ed

2010-01-01

Oak Ridge National Laboratory (ORNL) is collaborating with Waukesha Electric Systems (WES) to develop a high-temperature superconducting (HTSC) utility power transformer with primary and secondary coils cooled by liquid nitrogen. Since the vacuuminsulated cryogenic coil dewar surrounds the magnetic core limb and cannot form a shorted turn, non-conductive materials are required. Two test vessels and a small prototype dewar have been fabricated by Scorpius Space Launch Company with epoxy/fiberglass composites, using their proprietary PRESSURMAXX vessel technology. The effects of pumping time, bakeout temperature, and cryogenic vessel temperature on vacuum outgassing rates have been investigated. Outgassing rates of the individual materialsmore » used in vessel construction have also been measured. The results will be scaled up to determine the required pumping capacity for a full-size 25-MVA commercial transformer dewar.« less

Vacuum Studies of a Prototype Composite Coil Dewar for HTSC Transformers

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

Schwenterly, S W; Zhang, Y.; Pleva, E. F.

Oak Ridge National Laboratory (ORNL) is collaborating with Waukesha Electric Systems (WES) to develop a high-temperature superconducting (HTSC) utility power transformer with primary and secondary coils cooled by liquid nitrogen. Since the vacuum-insulated cryogenic coil dewar surrounds the magnetic core limb and cannot form a shorted turn, non-conductive materials are required. Two test vessels and a small prototype dewar have been fabricated by Scorpius Space Launch Company with epoxy/fiberglass composites, using their proprietary PRESSURMAXX vessel technology. The effects of pumping time, bakeout temperature, and cryogenic vessel temperature on vacuum outgassing rates have been investigated. Outgassing rates of the individual materialsmore » used in vessel construction have also been measured. The results will be scaled up to determine the required pumping capacity for a full-size 25-MVA commercial transformer dewar.« less

A magnetic induction heating system with multi-cascaded coils and adjustable magnetic circuit for hyperthermia.

PubMed

Huang, Chi-Fang; Chao, Hsuan-Yi; Chang, Hsun-Hao; Lin, Xi-Zhang

2016-01-01

Based on the characteristics of cancer cells that cannot survive in an environment with temperature over 42 °C, a magnetic induction heating system for cancer treatment is developed in this work. First, the methods and analyses for designing the multi-cascaded coils magnetic induction hyperthermia system are proposed, such as internal impedance measurement of power generator, impedance matching of coils, and analysis of the system. Besides, characteristics of the system are simulated by a full-wave package for engineering optimization. Furthermore, by considering the safety factor of patients, a two-sectional needle is designed for hyperthermia. Finally, this system is employed to test the liver of swine in ex-vivo experiments, and through Hematoxylin and Eosin (H&E) stain and NADPH oxidase activity assay, the feasibility of this system is verified.

Magnetic suspension and balance system advanced study, phase 2

NASA Technical Reports Server (NTRS)

Boom, R. W.; Abdelsalam, M. K.; Eyssa, Y. M.; Mcintosh, G. E.

1990-01-01

The design improvements for the system encompass 14 or 18 external superconductive coils mounted on a 8 x 8 foot wind tunnel, a superconductive model core magnet on a holmium mandrel to fit an F-16 model, model wings of permanent magnet material Nd2Fe14B, and fiber glass epoxy structure. The Magnetic Suspension and Balance System (MSBS) advanced design is confirmed by the successful construction and test of a full size superconductive model core solenoid with holmium mandrel. The solenoid is 75 cm long and 12.6 cm in diameter and produces 6.1 tesla for a hold time of 47 minutes. An integrated coil system design of a new compact configuration without specific coils for roll or pitch shows promise of simplicity; magnet reductions of 30 percent compared to the most recent 1985 design are possible.

NASA superconducting magnetic mirror facility

NASA Technical Reports Server (NTRS)

Reinmann, J. J.; Swanson, M. C.; Nichols, C. R.; Obloy, S. J.; Nagy, L. A.; Brady, F. J.

1973-01-01

This report summarizes the design details and initial test results of a superconducting magnetic mirror facility that has been constructed at NASA Lewis Research Center for use in thermonuclear research. The magnet system consists of four solenoidal coils which are individually rated at 5.0 T. Each coil is composed of an inner, middle, and outer winding. The inner winding is wound of stabilized Nb3SN superconducting ribbon, and the middle and outer windings are wound of stabilized Nb-Ti superconducting wire. When arranged in the mirror geometry, the four coils will produce 8.7 T at the mirrors and a 1.8 mirror ratio. The magnet has a 41-cm diameter clear bore which is open to atmosphere. Distance between the mirrors is 111 cm. Presently there are only three magnets in the facility; the fourth magnet is being rebuilt.

RF Magnetic Field Uniformity of Rectangular Planar Coils for Resonance Imaging

DTIC Science & Technology

2016-02-04

coil with square -shaped overlapping turns along the 135mm length of the coil. This paper compares these two coils to determine which has a more...in which, the coil arrays consist of a few square or circular coils side-by-side or overlapping. Mobile unilateral NMR/MRI scanners were...magnetic field along the length of a normal rectangular coil (NRC) and a rectangular coil with overlapping square -shaped turns (RCOS). The RCOS coil is

Experimental measurement of coil-rod-coil block copolymer tracer diffusion through entangled coil homopolymers

PubMed Central

Wang, Muzhou; Timachova, Ksenia; Olsen, Bradley D.

2014-01-01

The diffusion of coil-rod-coil triblock copolymers in entangled coil homopolymers is experimentally measured and demonstrated to be significantly slower than rod or coil homopolymers of the same molecular weight. A model coil-rod-coil triblock was prepared by expressing rodlike alanine-rich α-helical polypeptides in E. coli and conjugating coillike poly(ethylene oxide) (PEO) to both ends to form coil-rod-coil triblock copolymers. Tracer diffusion through entangled PEO homopolymer melts was measured using forced Rayleigh scattering at various rod lengths, coil molecular weights, and coil homopolymer concentrations. For rod lengths, L, that are close to the entanglementh length, a, the ratio between triblock diffusivity and coil homopolymer diffusivity decreases monotonically and is only a function of L/a, in quantitative agreement with previous simulation results. For large rod lengths, diffusion follows an arm retraction scaling, which is also consistent with previous theoretical predictions. These experimental results support the key predictions of theory and simulation, suggesting that the mismatch in curvature between rod and coil entanglement tubes leads to the observed diffusional slowing. PMID:25484454

Numerical design of an EBIS collector to optimize electron collection and ion extraction

NASA Astrophysics Data System (ADS)

Dietrich, Jürgen

1990-12-01

For the Frankfurt EBIS (R. Becker et al., Nucl. Instr. and Meth. B24/25 (1987) 838, ref. [1]), a new collector was designed using the relativistic electron optics program EGUN (W.B. Herrmannsfeldt, SLAC-331 (1988), ref. [2]) and the magnetic field program INTMAG (R. Becker, Nucl. Instr. and Meth. B42 (1989) 303, ref. [3]). To model the fringing field of the main solenoid, a bucking coil and a cylindrical shim is provided. The current of the bucking coil and the position and shape of the shim are optimized with INTMAG for minimum fringing field to allow expansion of the electron beam by its space charge. The magnetic field data output from INTMAG is directly used as input for EGUN to calculate the electron and ion trajectories. The initial conditions for the trajectories were computed from the paraxial ray equation. Different operation modes of the collector are investigated including the behaviour of secondary electrons.

Magnetic propulsion of a magnetic device using three square-Helmholtz coils and a square-Maxwell coil.

PubMed

Ha, Yong H; Han, Byung H; Lee, Soo Y

2010-02-01

We introduce a square coil system for remote magnetic navigation of a magnetic device without any physical movements of the coils. We used three square-Helmholtz coils and a square-Maxwell coil for magnetic propulsion of a small magnet along the desired path. All the square coils are mountable on a cubic frame that has an opening to accommodate a living subject. The square-Helmholtz coils control the magnetic propulsion direction by generating uniform magnetic field along the desired direction while the square-Maxwell coil controls the propulsion force by generating magnetic gradient field. We performed magnetic propulsion experiments with a down-scaled coil set and a three-channel coil driver. Experimental results demonstrate that we can use the square coil set for magnetic navigation of a magnetic device without any physical movements of the coils.

A nonintrusive method for measuring the operating temperature of a solenoid-operated valve

NASA Astrophysics Data System (ADS)

Kryter, Robert C.

Experimental data are presented to show that the in-service operating temperature of a solenoid operated valve (SOV) can be inferred simply and nondisruptively by using the copper winding of the solenoid coil as a self-indicating, permanently available resistance thermometer. The principal merits of this approach include: (1) there is no need for an add-on temperature sensor, (2) the true temperature of a critical and likely the hottest, part of the SOV (namely, the electrical coil) is measured directly, (3) temperature readout can be provided at any location at which the SOV electrical lead wires are accessible (even though remote from the valve), (4) the SOV need not be disturbed (whether normally energized or deenergized) to measure its temperature in situ, and (5) the method is applicable to all types of SOVs, large and small, ac- and dc-powered. Laboratory tests comparing temperatures measured both by coil resistance and by a conventional thermometer placed in contact with the external surface of the potted solenoid coil indicate that temperature within the coil may be on the order of 40 C higher than that measured externally, a fact that is important to life-expectancy calculations made on the basis of Arrhenius theory. Field practicality is illustrated with temperature measurements made using this method on a SOV controlling the flow of refrigerant in a large chilled-water air-conditioning system.

A Double-Coil TMS Method to Assess Corticospinal Excitability Changes at a Near-Simultaneous Time in the Two Hands during Movement Preparation

PubMed Central

Wilhelm, Emmanuelle; Quoilin, Caroline; Petitjean, Charlotte; Duque, Julie

2016-01-01

Background: Many previous transcranial magnetic stimulation (TMS) studies have investigated corticospinal excitability changes occurring when choosing which hand to use for an action, one of the most frequent decision people make in daily life. So far, these studies have applied single-pulse TMS eliciting motor-evoked potential (MEP) in one hand when this hand is either selected or non-selected. Using such method, hand choices were shown to entail the operation of two inhibitory mechanisms, suppressing MEPs in the targeted hand either when it is non-selected (competition resolution, CR) or selected (impulse control, IC). However, an important limitation of this “Single-Coil” method is that MEPs are elicited in selected and non-selected conditions during separate trials and thus those two settings may not be completely comparable. Moreover, a more important problem is that MEPs are computed in relation to the movement of different hands. The goal of the present study was to test a “Double-Coil” method to evaluate IC and CR preceding the same hand responses by applying Double-Coil TMS over the two primary motor cortices (M1) at a near-simultaneous time (1 ms inter-pulse interval). Methods: MEPs were obtained in the left (MEPLEFT) and right (MEPRIGHT) hands while subjects chose between left and right hand key-presses in blocks using a Single-Coil or a Double-Coil method; in the latter blocks, TMS was either applied over left M1 first (TMSLRM1 group, n = 12) or right M1 first (TMSRLM1 group, n = 12). Results: MEPLEFT were suppressed preceding both left (IC) and right (CR) hand responses whereas MEPRIGHT were only suppressed preceding left (CR) but not right (IC) hand responses. This result was observed regardless of whether Single-Coil or Double-Coil TMS was applied in the two subject groups. However, in the TMSLRM1 group, the MEP suppression was attenuated in Double-Coil compared to Single-Coil blocks for both IC and CR, when probed with MEPLEFT (elicited by the second pulse). Conclusions: Although Double-Coil TMS may be a reliable method to assess bilateral motor excitability provided that a RM1-LM1 pulse order is used, further experiments are required to understand the reduced MEPLEFT changes in Double-Coil blocks when the LM1-RM1 pulse order was used. PMID:27014020

Embolization of the Gastroduodenal Artery Before Selective Internal Radiotherapy: A Prospectively Randomized Trial Comparing Platinum-Fibered Microcoils with the Amplatzer Vascular Plug II

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

Pech, Maciej, E-mail: maciej.pech@med.ovgu.de; Kraetsch, Annett; Wieners, Gero

2009-05-15

The Amplatzer Vascular Plug II (AVP II) is a novel device for transcatheter vessel occlusion, for which only limited comparative data exist. Embolotherapy of the gastroduodenal artery (GDA) is essential before internal radiotherapy (SIRT) in order to prevent radiation-induced peptic ulcerations due to migration of yttrium-90 microspheres. The purpose of this study was to compare the vascular anatomical limitations, procedure time, effectiveness, and safety of embolization of the GDA with coils versus the AVP II. Fifty patients stratified for SIRT were prospectively randomized for embolization of the GDA with either coils or the AVP II. The angle between the aortamore » and the celiac trunk, diameter of the GDA, fluoroscopy time and total time for embolization, number of embolization devices, complications, and durability of vessel occlusion at follow-up angiography for SIRT were recorded. A t-test was used for statistical analysis. Embolizations with either coils or the AVP II were technically feasible in all but two patients scheduled for embolization of the GDA with the AVP II. In both cases the plug could not be positioned due to the small celiac trunk outlet angles of 17{sup o} and 21{sup o}. The mean diameter of the GDA was 3.7 mm (range, 2.2-4.8 mm) for both groups. The procedures differed significantly in fluoroscopy time (7.8 min for coils vs. 2.6 min for the AVP II; P < 0.001) and embolization time (23.1 min for coils vs. 8.8 min for the AVP II; P < 0.001). A mean of 6.0 {+-} 3.2 coils were used for GDA embolization, while no more than one AVP II was needed for successful vessel occlusion (P < 0.001). One coil migration occurred during coil embolization, whereas no procedural complication was encountered with the use of the AVP II. Vessel reperfusion was noted in only one patient, in whom coil embolization was performed. In conclusion, embolization of the GDA with the AVP II is safe, easy, rapid, and highly effective; only an extremely sharp-angled celiac trunk outlet represented an anatomical limitation for device deployment.« less

An innovative design for using flexible printed coils for magnetostrictive-based longitudinal guided wave sensors in steel strand inspection

NASA Astrophysics Data System (ADS)

Tse, P. W.; Liu, X. C.; Liu, Z. H.; Wu, B.; He, C. F.; Wang, X. J.

2011-05-01

Magnetostrictive sensors (MsSs) that can excite and receive guided waves are commonly used in detecting defects that may occur in cables and strands for supporting heavy structures. A conventional MsS has a hard sensing coil that is wound onto a bobbin with electric wires to generate the necessary dynamic magnetic field to excite the desired guided waves. This tailor-made hard coil is usually bulky and is not flexible enough to fit steel strands of various sizes. The conventional MsS also cannot be mounted to any steel strand that does not have a free end to allow the bobbin to pass through the structure of the tested strand. Such inflexibilities limit the use of conventional MsSs in practical situations. To solve these limitations, an innovative type of coil, called a flexible printed coil (FPC), which is made out of flexible printed film, has been designed to replace the inflexible hard coil. The flexible structure of the FPC ensures that the new MsS can be easily installed on and removed from steel strands with different diameters and without free ends. Moreover, the FPC-based MsS can be wrapped into multiple layers due to its thin and flexible design. Although multi-layer FPC creates a minor asymmetry in the dynamic magnetic field, the results of finite element analysis and experiments confirm that the longitudinal guided waves excited by a FPC-based MsS are comparable to those excited by a conventional hard coil MsS. No significant reduction in defect inspection performance was found; in fact, further advantages were identified when using the FPC-based MsS. When acting as the transmitter, the innovative FPC-based MsS can cover a longer inspection length of strand. When acting as the receiver, the FPC-based MsS is more sensitive to smaller defects that are impossible to detect using a hard coil MsS. Hence, the multi-layer FPC-based MsS has great potential for replacing the conventional hard coil MsS because of its convenient installation, and ease of fitting to different strand diameters; it is smaller, and, most importantly, performs much better in strand defect detection.

Study on electromagnetic characteristics of the magnetic coupling resonant coil for the wireless power transmission system.

PubMed

Wang, Zhongxian; Liu, Yiping; Wei, Yonggeng; Song, Yilin

2018-01-01

The resonant coil design is taken as the core technology in the magnetic coupling resonant wireless power transmission system, which achieves energy transmission by the coupling of the resonant coil. This paper studies the effect of the resonant coil on energy transmission and the efficiency of the system. Combining a two-coil with a three-coil system, the optimum design method for the resonant coil is given to propose a novel coil structure. First, the co-simulation methods of Pspice and Maxwell are used. When the coupling coefficient of the resonant coil is different, the relationship between system transmission efficiency, output power, and frequency is analyzed. When the self-inductance of the resonant coil is different, the relationship between the performance and frequency of the system transmission is analyzed. Then, two-coil and three-coil structure models are built, and the parameters of the magnetic field of the coils are calculated and analyzed using the finite element method. In the end, a dual E-type simulation circuit model is used to optimize the design of the novel resonance coil. The co-simulation results show that the coupling coefficients of the two-coil, three-coil, and novel coil systems are 0.017, 0.17 and 0.0126, respectively. The power loss of the novel coil is 16.4 mW. There is an obvious improvement in the three-coil system, which shows that the magnetic leakage of the field and the energy coupling are relatively small. The new structure coil has better performance, and the load loss is lower; it can improve the system output power and transmission efficiency.

Applying graph theory to protein structures: an atlas of coiled coils.

PubMed

Heal, Jack W; Bartlett, Gail J; Wood, Christopher W; Thomson, Andrew R; Woolfson, Derek N

2018-05-02

To understand protein structure, folding and function fully and to design proteins de novo reliably, we must learn from natural protein structures that have been characterised experimentally. The number of protein structures available is large and growing exponentially, which makes this task challenging. Indeed, computational resources are becoming increasingly important for classifying and analysing this resource. Here, we use tools from graph theory to define an atlas classification scheme for automatically categorising certain protein substructures. Focusing on the α-helical coiled coils, which are ubiquitous protein-structure and protein-protein interaction motifs, we present a suite of computational resources designed for analysing these assemblies. iSOCKET enables interactive analysis of side-chain packing within proteins to identify coiled coils automatically and with considerable user control. Applying a graph theory-based atlas classification scheme to structures identified by iSOCKET gives the Atlas of Coiled Coils, a fully automated, updated overview of extant coiled coils. The utility of this approach is illustrated with the first formal classification of an emerging subclass of coiled coils called α-helical barrels. Furthermore, in the Atlas, the known coiled-coil universe is presented alongside a partial enumeration of the 'dark matter' of coiled-coil structures; i.e., those coiled-coil architectures that are theoretically possible but have not been observed to date, and thus present defined targets for protein design. iSOCKET is available as part of the open-source GitHub repository associated with this work (https://github.com/woolfson-group/isocket). This repository also contains all the data generated when classifying the protein graphs. The Atlas of Coiled Coils is available at: http://coiledcoils.chm.bris.ac.uk/atlas/app.

Crystal structure of a super leucine zipper, an extended two-stranded super long coiled coil

PubMed Central

Diao, Jiasheng

2010-01-01

Coiled coil is a ubiquitous structural motif in proteins, with two to seven alpha helices coiled together like the strands of a rope, and coiled coil folding and assembly is not completely understood. A GCN4 leucine zipper mutant with four mutations of K3A, D7A, Y17W, and H18N has been designed, and the crystal structure has been determined at 1.6 Å resolution. The peptide monomer shows a helix trunk with short curved N- and C-termini. In the crystal, two monomers cross in 35° and form an X-shaped dimer, and each X-shaped dimer is welded into the next one through sticky hydrophobic ends, thus forming an extended two-stranded, parallel, super long coiled coil rather than a discrete, two-helix coiled coil of the wild-type GCN4 leucine zipper. Leucine residues appear at every seventh position in the super long coiled coil, suggesting that it is an extended super leucine zipper. Compared to the wild-type leucine zipper, the N-terminus of the mutant has a dramatic conformational change and the C-terminus has one more residue Glu 32 determined. The mutant X-shaped dimer has a large crossing angle of 35° instead of 18° in the wild-type dimer. The results show a novel assembly mode and oligomeric state of coiled coil, and demonstrate that mutations may affect folding and assembly of the overall coiled coil. Analysis of the formation mechanism of the super long coiled coil may help understand and design self-assembling protein fibers. PMID:20027625

Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery.

PubMed

Chittiboina, Prashant; Talagala, S Lalith; Merkle, Hellmut; Sarlls, Joelle E; Montgomery, Blake K; Piazza, Martin G; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R; Oldfield, Edward H; Koretsky, Alan P; Butman, John A

2016-12-01

OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing's disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra-high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm 3 and 0.15 × 0.15 × 0.30 mm 3 , respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p < 0.01) in the SNR were inversely proportional to the distance from the ESC tip to the anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult pituitary adenomas and identify microscopic invasion of the dura or cavernous sinus.

Endosphenoidal coil for intraoperative magnetic resonance imaging of the pituitary gland during transsphenoidal surgery

PubMed Central

Chittiboina, Prashant; Talagala, S. Lalith; Merkle, Hellmut; Sarlls, Joelle E.; Montgomery, Blake K.; Piazza, Martin G.; Scott, Gretchen; Ray-Chaudhury, Abhik; Lonser, Russell R.; Oldfield, Edward H.; Koretsky, Alan P.; Butman, John A.

2016-01-01

OBJECTIVE Pituitary MR imaging fails to detect over 50% of microadenomas in Cushing’s disease and nearly 80% of cases of dural microinvasion. Surface coils can generate exceptionally high-resolution images of the immediately adjacent tissues. To improve imaging of the pituitary gland, a receive-only surface coil that can be placed within the sphenoid sinus (the endosphenoidal coil [ESC]) during transsphenoidal surgery (TSS) was developed and assessed. METHODS Five cadaver heads were used for preclinical testing of the ESC. The ESC (a double-turn, 12-mm-diameter surface coil made from 1-mm-diameter copper wire) was developed to obtain images in a 1.5-T MR scanner. The ESC was placed (via a standard sublabial TSS approach) on the anterior sella face. Clinical MR scans were obtained using the 8-channel head coil and ESC as the receiver coils. Using the ESC, ultra–high-resolution, 3D, balanced fast field echo (BFFE) and T1-weighted imaging were performed at resolutions of 0.25 × 0.25 × 0.50 mm3 and 0.15 × 0.15 × 0.30 mm3, respectively. RESULTS Region-of-interest analysis indicated a 10-fold increase in the signal-to-noise ratio (SNR) of the pituitary when using the ESC compared with the 8-channel head coil. ESC-related improvements (p < 0.01) in the SNR were inversely proportional to the distance from the ESC tip to the anterior pituitary gland surface. High-resolution BFFE MR imaging obtained using ESC revealed a number of anatomical features critical to pituitary surgery that were not visible on 8-channel MR imaging, including the pituitary capsule, the intercavernous sinus, and microcalcifications in the pars intermedia. These ESC imaging findings were confirmed by the pathological correlation with whole-mount pituitary sections. CONCLUSIONS ESC can significantly improve SNR in the sellar region intraoperatively using current 1.5-T MR imaging platforms. Improvement in SNR can provide images of the sella and surrounding structures with unprecedented resolution. Clinical use of this ESC may allow for MR imaging detection of previously occult pituitary adenomas and identify microscopic invasion of the dura or cavernous sinus. PMID:26991390

Microcoil embolization during abdominal vascular interventions through microcatheters with a tip of 2 French or less.

PubMed

Miyayama, Shiro; Yamashiro, Masashi; Hattori, Yuki; Orito, Nobuaki; Matsui, Ken; Tsuji, Kazunobu; Yoshida, Miki; Matsui, Osamu

2011-05-01

The aim of this study was to evaluate the technical aspects of embolization using microcoils through a microcatheter with a tip of 2F or smaller during abdominal vascular interventions. Coil embolization through a microcatheter with a tip of 2F or smaller was attempted in 73 procedures. Two types of microcoil-Liquid Coil (Boston Scientific, Watertown, MA, USA) and Tornado Coil (Cook, Bloomington, IN, USA)-were deployed through four types of thinner microcatheter [2F tip (n = 49) and 1.8F tip (n = 24)]. Coil jams in the microcatheter and coil migration were evaluated. In total, 286 microcoils were placed (mean ± SD, 3.9 ± 4.3 coils per procedure, range 1-32 coils). In 19 procedures (26.9%), Liquid Coils were used alone. In 44 (60.3%), Tornado Coils were used alone. In 10 (13.7%), Liquid Coils and Tornado Coils were combined. There were no coil jams in the microcatheter in this series. One Tornado Coil (0.3%) delivered into the gastroduodenal artery migrated to the right hepatic artery. Liquid Coils and Tornado Coils can be placed through a thinner microcatheter without difficulty. However, there is a risk of coil migration in large vessels or at the proximal site because the catheter tip is not stabilized.

Coupled circuit numerical analysis of eddy currents in an open MRI system.

PubMed

Akram, Md Shahadat Hossain; Terada, Yasuhiko; Keiichiro, Ishi; Kose, Katsumi

2014-08-01

We performed a new coupled circuit numerical simulation of eddy currents in an open compact magnetic resonance imaging (MRI) system. Following the coupled circuit approach, the conducting structures were divided into subdomains along the length (or width) and the thickness, and by implementing coupled circuit concepts we have simulated transient responses of eddy currents for subdomains in different locations. We implemented the Eigen matrix technique to solve the network of coupled differential equations to speed up our simulation program. On the other hand, to compute the coupling relations between the biplanar gradient coil and any other conducting structure, we implemented the solid angle form of Ampere's law. We have also calculated the solid angle for three dimensions to compute inductive couplings in any subdomain of the conducting structures. Details of the temporal and spatial distribution of the eddy currents were then implemented in the secondary magnetic field calculation by the Biot-Savart law. In a desktop computer (Programming platform: Wolfram Mathematica 8.0®, Processor: Intel(R) Core(TM)2 Duo E7500 @ 2.93GHz; OS: Windows 7 Professional; Memory (RAM): 4.00GB), it took less than 3min to simulate the entire calculation of eddy currents and fields, and approximately 6min for X-gradient coil. The results are given in the time-space domain for both the direct and the cross-terms of the eddy current magnetic fields generated by the Z-gradient coil. We have also conducted free induction decay (FID) experiments of eddy fields using a nuclear magnetic resonance (NMR) probe to verify our simulation results. The simulation results were found to be in good agreement with the experimental results. In this study we have also conducted simulations for transient and spatial responses of secondary magnetic field induced by X-gradient coil. Our approach is fast and has much less computational complexity than the conventional electromagnetic numerical simulation methods. Copyright © 2014 Elsevier Inc. All rights reserved.