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ABSTRACT: Shielding of magnetic fields (magnetic shielding) by rare earth-based REBCO coated conductors with a highly oriented superconducting layer was measured. The shielding of magnetic fields was measured using a Hall effect sensor installed between bundles consisting of commercial REBCO conductors 12 mm in width. Measurements of the shielding of magnetic fields by other commercial high-T<sub>c</sub> superconductors were performed for comparison. The shielding of magnetic fields was found to depend on the number of conductors in the bundle and the route of the applied magnetic fields and was observed even for fields over 10 T. In steady magnetic fields, a temporal change in the shielding of magnetic fields, that is, a decay of shielding currents induced in conductors against applied magnetic fields, was measured. The temporal change of the shielding of magnetic fields exhibited the behavior typical of high-T<sub>c</sub> superconductors, as explained by the flux creep model. Remanent magnetic fields measured in the experiments of the shielding of magnetic fields suggest that the bundle can be used as a magnet. A quasi-bulk magnet consisting of 100 Zr-doped Zr:REBCO conductors could hold over 3 T at 4.2 K.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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ABSTRACT: Because of their high critical fields, high- T <sub>c</sub> superconductors (HTS) are considered to be the only solution to dramatically increase the highest fields of NMR magnets. We have successfully demonstrated that a 500 MHz HTS/LTS NMR system with a Bi-2223 innermost coil could be used for solution NMR in a driven-mode operation. As the next step, the upgrade of the 920 MHz NMR system installed at the Tsukuba Magnet Laboratory is underway. The innermost Nb<sub>3</sub>Sn coil has been replaced by a Bi-2223 coil. The coil was fabricated as a layer-wound coil using five Bi-2223 conductors reinforced with bronze tapes. It was connected in series with the outer Nb<sub>3</sub>Sn and NbTi coils. The magnet is expected to generate a field of 24.2 T (1.03 GHz of <sup>1</sup>H resonance frequency) at an operating current of 244.4 A. The test using the Bi-2223 coil and the outer Nb<sub>3</sub>Sn coils in combination was successfully carried out. The coil has been installed in the 1.03 GHz NMR magnet. Its cooling and operation are scheduled to take place within Fiscal Year 2010.
IEEE Transactions on Appiled Superconductivity 07/2011; · 1.04 Impact Factor
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ABSTRACT: This work presents and evaluates the PixelLaser system, designed to estimate range-to-obstacle scans from single images. Its visual pipeline uses nearest-neighbor texture-matching to segment groundplane (traversable) texture from non-groundplane (obstacle) texture. Using the known pose of a webcamera, the system then transforms these segmentations into range-scans. This paper presents a thorough evaluation of the range accuracy obtained in the resulting scans. In addition, it presents three practical robot applications that use PixelLaser's monocular ranging: (a) a safe-wandering agent, (b) a Monte-Carlo localizer, and (c) a mapping system using CoreSLAM. In each case, algorithms that usually depend on laser scans have succeed with PixelLaser data instead.
Technologies for Practical Robot Applications (TePRA), 2011 IEEE Conference on; 05/2011
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ABSTRACT: Motion-compensated (MC) prediction is one of the most effective coding tools for high-compression video coding. In former works, adaptive interpolation filter (AIF) technology, which improves the coding performance of the fractional-pel MC, has been proposed. As for the real-time codec system, the implementation of AIF based on the Wiener filter algorithm is difficult because of its high computational complexity. To overcome this problem, in this paper, we propose a low-complexity AIF scheme, which can maintain the coding performance achieved by the conventional AIF. The key technology is the efficient filter design process based on the amplitude characteristic analysis with the precise estimation of MC error signal. The experimental result confirmed that almost the same coding performance was maintained at only 30% of the complexity compared to the conventional AIF.
Image Processing (ICIP), 2010 17th IEEE International Conference on; 10/2010
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ABSTRACT: Bug prediction models are often used to help allocate software quality assurance efforts (e.g. testing and code reviews). Mende and Koschke have recently proposed bug prediction models that are effort-aware. These models factor in the effort needed to review or test code when evaluating the effectiveness of prediction models, leading to more realistic performance evaluations. In this paper, we revisit two common findings in the bug prediction literature: 1) Process metrics (e.g., change history) outperform product metrics (e.g., LOC), 2) Package-level predictions outperform file-level predictions. Through a case study on three projects from the Eclipse Foundation, we find that the first finding holds when effort is considered, while the second finding does not hold. These findings validate the practical significance of prior findings in the bug prediction literature and encourage their adoption in practice.
Software Maintenance (ICSM), 2010 IEEE International Conference on; 10/2010
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V. Lakhian,
F. Bocquet,
D. Brocilo,
G.D. Harvel,
J.-S. Chang,
D. Ewing,
M. Watanabe,
H. Matsubara,
H. Hirata, S. Matsumoto,
P.T. Fanson
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ABSTRACT: The discharge characteristics of a ring-type flow-stabilized pulsed corona discharge radical shower system (RCDRS) were investigated. An RCDRS with six hollow electrodes was studied. A low dc voltage charging of an ignition coil-type power supply was used to generate a pulse high voltage. Experiments were conducted for an applied charging dc voltage from 5 V to 18 V, a pulse repetition rate from 50 Hz to 200 Hz, and an injected air flow rate from 2.5 to 4.6 L/min per hollow electrode. The discharge characteristics were measured using current and voltage probes, and the morphology of the discharge was observed using a CCD camera. The pulsed waveforms of current, voltage, and power (secondary side output) were studied in terms of the input power (primary side), as well as the current and voltage, with the observed optical images for optimization. The results show that the maximum discharge current, voltage, and power increase with increasing primary side dc voltage or power. The pulse repetition rate affected the maximum discharge characteristics in terms of the primary side dc voltage, while the air flow rate did not. The maximum volume averaged plasma density is on the order of 10<sup>11</sup> ions/cm<sup>3</sup> for the 10-cm diameter and 5-cm-long flow channel volume.
IEEE Transactions on Industry Applications 09/2010; · 1.66 Impact Factor
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ABSTRACT: This paper reports application results of Monte-Carlo Tree Search (MCTS) for a practical problem. In this paper, a reentrant scheduling problem is considered as a practical problem which has been addressed by our previous works. MCTS introduced by Coulom is a best-first search where the pseudorandom simulations guide the solution of problem. Recent improvements on MCTS have produced strong computer Go program, which has a large search space, and the success is a hot topic for selecting the best move. So far, most of reports about MCTS have been on two-player game, and MCTS has been applied rarely in one-player perfect-information games. MCTS does not need an admissible heuristic, so the application of MCTS for one-player games might be an interesting alternative. Additionally, one-player games like puzzles are determinately operated only by one player's decision, so sequences of changes in state are describable as a network diagram of interdependence of operations. Therefore if MCTS for one-player games is considered as a meta-heuristic algorithm, we can use this algorithm for not only many practical problems, but also combinatorial optimization problems. Especially as MCTS does not fully depend on evaluation function, so the solutions based on MCTS remain effective if objective function of problem is modified. This paper firstly investigated on the application of Single Player MCTS (SP-MCTS) introduced by Schadd et al. Next this paper showed the effectiveness of new simulation strategies on SP-MCTS by numerical experiments. Based on the results, this paper discussed the application potentiality of SP-MCTS for a practical reentrant scheduling problem.
Computers and Industrial Engineering (CIE), 2010 40th International Conference on; 08/2010
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ABSTRACT: The electromagnetic (EM) wave generated by partial discharge (PD) is analyzed using electric dipole model. The pulse electric and magnetic fields are described by analytical functions. The interaction of patch antenna or microstrip antenna with the EM wave is investigated on EM theory, which leads to a simple transmission-line model. Then, the response of patch antenna to the PD-initiated EM wave is numerically analyzed as a circuit transient. It is found that the generated EM fields and the response of patch antenna strongly depend on how fast PD develops. The sensitivity of patch antenna to PD is expressed in a simple chart. The analytical results are verified by an experiment in which the EM wave from a short-gap discharge is detected by the patch-antenna PD sensor. The patch-antenna system is expected to be used for detecting PDs occurring inner parts such as winding's inter-turn.
IEEE Transactions on Dielectrics and Electrical Insulation 07/2010; · 1.09 Impact Factor
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T. Kiyoshi,
Seyong Choi, S. Matsumoto,
K. Zaitsu,
T. Hase,
T. Miyazaki,
A. Otsuka,
M. Yoshikawa,
M. Hamada,
M. Hosono,
Y. Yanagisawa,
H. Nakagome,
M. Takahashi,
T. Yamazaki,
H. Maeda
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ABSTRACT: Using high-T<sub>c</sub> superconductors (HTS) is considered to be the only solution to dramatically increase the highest fields of NMR magnets because of their high critical fields. However, it is not easy to apply HTS to an NMR spectrometer (HTS-NMR) because a persistent-mode operation with HTS cannot satisfy the field stability of 0.01 ppm/h at present. To overcome this problem, we are now developing an HTS-NMR spectrometer in a driven-mode operation. As the first step, a layer-wound coil was fabricated with bronze-reinforced Bi-2223 conductors. Instead of the Nb<sub>3</sub>Sn coil, the Bi-2223 coil was installed as the innermost part of an existing NMR magnet. The magnet operated at a field of 11.7 T with a highly stabilized power supply. NMR measurements were carried out, and it was demonstrated that the quality of the multi-dimensional NMR spectra on the protein was equivalent to that obtained with a persistent-mode system. The next step will be to demonstrate its usefulness as a high-field NMR system. The upgrade of the 920 MHz NMR system installed at the Tsukuba Magnet Laboratory is underway. Its innermost coil is scheduled to be replaced by a Bi-2223 layer-wound coil for 2010. Its target field is 24.2 T (1.03 GHz).
IEEE Transactions on Appiled Superconductivity 07/2010; · 1.04 Impact Factor
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ABSTRACT: The present paper suggests a new type of TE<sub>10</sub>-TE<sub>20</sub> mode transducer vertically excited in a way of crossing the electric fields of an over-moded waveguide (OMWG) and a single-mode one (SMWG). By optimizing a matching element the mode-conversion efficiency more than 99% is obtained over the fractional bandwidth of about 17%. The reason why such a good performance is obtained is because the present mode transducer is free from undesired mode excitation in principle. The validity of the design concept is also confirmed experimentally. Moreover, an elimination technique of unwanted resonant response is successfully demonstrated.
Microwave Symposium Digest (MTT), 2010 IEEE MTT-S International; 06/2010
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ABSTRACT: This paper presents novel exposure module-based patterning technique for realizing continuous lithography process on fiber substrates. Fine patterns (better than 10 ¿m L/S) were successfully formed on the fiber with the diameter of 125 ¿m by using the exposure module. The exposure module exhibited advantages of low cost, easy alignment, high productivity and excellent compatibility with other microfabrication processes. It is an attractive patterning solution to the integration of functional devices and structures onto the fiber substrates.
Micro Electro Mechanical Systems (MEMS), 2010 IEEE 23rd International Conference on; 02/2010
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ABSTRACT: This paper describes a constitution method of a novel TE<sub>10</sub>-TE<sub>20</sub> mode transducer utilizing an H-plane right-angled corner composed of a standard waveguide and an over-moded one. By placing several metallic posts in the corner junction for both good mode-conversion and low return loss, and optimizing their positions and diameters by the use of the H-plane planar circuit approach together with the short-circuiting method of fictitious ports, a compact and easy-to-fabricate mode transducer is realized. Next, an out-of-phase power divider is designed by utilizing this mode transducer, and relatively wide-band characteristics are obtained for both power-split balance and 180° phase difference. Finally, the validity of the design result is confirmed by experiments.
Microwave Conference, 2009. APMC 2009. Asia Pacific; 01/2010
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ABSTRACT: A method using scatterometry for simultaneous focus and critical dimension (CD) control method has been developed. Our focus and CD measurement method uses a five-layer scatterometry model and provides stable focus measurement when the exposure dose fluctuates. We utilize this feature and consider applying it to the response surface methodology model for focus and CD control. This control optimizes focus and calculates the correct dose allowing for the focus effect. We have confirmed that this method controls photoresist shape accurately and reduces the CD variation for 65 nm devices by 80%.
IEEE Transactions on Semiconductor Manufacturing 12/2009; · 0.72 Impact Factor
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ABSTRACT: We propose a control IC for boost converter based on new strategies. There are three strategies; ultralow-voltage input, operating energy of the boost converter used proposed IC powered by own output, and maximum power point tracking (MPPT). The boost converter starts at 0.36 V by using the proposed IC and operates with a single solar cell. The power generated by the photovoltaic module with the proposed IC is about 1.4 times higher because the MPPT works well. The photovoltaic module with the proposed IC shows superior performance compared with the conventional one.
Power Semiconductor Devices & IC's, 2009. ISPSD 2009. 21st International Symposium on; 07/2009
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ABSTRACT: In this study, we investigated in field properties of high- Tc superconductor (HTS) tapes electrically as well as mechanically. Metallic reinforced Bi-2223/Ag superconductor tapes were used in this work. The critical current ( Ic ), which is highly dependent on the magnetic field, was measured using fields applied parallel and perpendicular to the tape surface. The conductor was exposed to fields of up to 28 T at 4.2 K. In order to confirm the performance of tapes in practical NMR operation, Ic was also measured around 2 K. The conductor was wound on a large diameter bobbin and mechanical properties were then measured as the coil current was increased. Finally, we verified the conductor properties from coil Ic and maximum stress/strain of it.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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N. Ayai,
K. Yamazaki,
M. Kikuchi,
G. Osabe,
H. Takaaze,
H. Takayama,
S.-i. Kobayashi,
J. Fujikami,
K. Hayashi,
K.-i. Sato,
K. Osamura,
H. Kitaguchi, S. Matsumoto,
T. Kiyoshi,
J.-i. Shimoyama
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ABSTRACT: Electrical and mechanical characteristics of Type HT tape, which is standard 4.2 mm wide DI-BSCCO tape reinforced with metallic tapes, have been evaluated. Longitudinal distributions of critical current and n-index in kilometer long Type HT tape has proved uniform from end to end just like the original insert tape, which is Type H tape. Type HT-CA reinforced with 50 mum thick heat-resistant copper alloy is highly balanced tape with high mechanical properties and low splice resistance. Type HT-SS reinforced with 20 mum thick stainless steel has the best mechanical properties, which has been demonstrated under the actual environment in high field magnet, namely the hoop stress load test energizing a one-turn coil in external high magnetic field and liquid helium.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: Magnetic flux concentration is a very important technique for the effective generation of high magnetic fields. We propose the use of the diamagnetism of a high T <sub>c</sub> bulk superconductor (HTS bulk) instead of ferromagnetic materials such as Ho and Dy. We fabricated a magnetic field concentrator using Gd-Ba-Cu-O bulk. The essential point was slits to suppress the current along the circumference. The concentrator was cooled at the center of a superconducting magnet with liquid helium. By increasing the external field to 1.00 T, a magnetic flux density of 3.20 T was obtained at the center of the concentrator. At an external field of 2.00 T, a field of 5.65 T was also obtained. A magnetic lens using HTS bulk was successfully demonstrated. The experimental results were well explained by numerical analyses assuming HTS bulk as a perfect conductor.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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ABSTRACT: Super high definition video such as 4 K digital cinema is expected as the quite attractive video application. With regard to the video transmission, recent compression coding standards are applicable for 4 K digital cinema. However, the typical implementation approach of a commercial video encoder is based on hardware architecture. As the limitation of hardware base implementation, once the equipment has been completed, further improvement such as supporting higher resolution video or adding unsupported coding tools would be pretty difficult. On the other hand, distributed computing by utilizing several PC platforms has become more typical as the approach for developing a high performance computer system. With regard to the real time application where precise timing control is required, the practical example of distributed computing system has not been existing yet. From this perspective, this paper describes the key technology necessary to realize full software implementation of real time video encoder by utilizing distributed computing technology.
Intelligent Signal Processing and Communication Systems, 2009. ISPACS 2009. International Symposium on; 02/2009
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F. Tachibana,
H. Sato,
T. Yamashita,
H. Hara,
T. Kitahara,
S. Nomura,
F. Yamane,
Y. Tsuboi,
K. Seki, S. Matsumoto,
Y. Watanabe,
M. Hamada
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ABSTRACT: A cell-based forward body-biasing technique to suppress the global process variation and its design flow are proposed. Latch-up free operation is guaranteed by embedded current source cells and limiter cells even when supply voltage is 1.2 V with small area overhead. By applying this technique to a media processor, the worst-case delay is reduced by 20% without sacrificing the maximum leakage spec.
Custom Integrated Circuits Conference, 2008. CICC 2008. IEEE; 10/2008
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ABSTRACT: As techniques for locating the fault position of the power feeding line of the optical submarine cable, the electric time domain reflector, and the AC resistance measurement are discussed. Authors measured the fault position of the cable that was subject to fault using these two methods. The actual fault point was directly located by divers using AC magnetic field detection method. Comparison of both results confirmed the validity of the electrical fault localization method. The frequency dependency of the pulse propagation velocity in the armored cable was obtained based on the measurement result of the frequency response of the AC resistance measurement of the cable.
OCEANS 2008; 10/2008
