Pulsed field loss characteristics of the Japanese test coil for the large coil task

This paper describes some results of an analytical calculation and the measurements of a pulsed field loss on the Japanese LCT conductor. The conductor, whose aspect ratio is around 2.5, is wound edge wise to reduce the pulsed field loss. The Japanese LCT coil, with the conductor thus designed, was evaluated to have a pulsed field loss of about 19W. This includes the loss of the helium vessel under the normal LCT test with a pulsed field of 0 to 0.14T. In addition, the loss measurement has been carried out up to 25 T/s. Measured results on the relation between the loss of a single strand and that of a whole strand pack well supports the validity of the loss analysis which includes a newly arranged set of analytical equations.     

Application of focused ion beam techniques and transmission electron microscopy to thin-film transistor failure analysis

The locations of process-induced defects in hydrogenated amorphous silicon thin-film transistors (a-Si:H TFTs), which are used as elements of active-matrix liquid crystal displays, were investigated by combining focused ion beam techniques with cross-sectional transmission electron microscopy (X-TEM). The FIB technique is applied to TFT failure analysis problems, which require considerable localised etching without inducing mechanical stress or damage at fragile failure locations. We demonstrate the manner in which these techniques are used to characterise TFT defects such as pinholes and portions of the multilayer damaged by mechanical stress. A dramatic improvement brought about by the FIB technique is the increase in temporal efficiency of sample preparations. X-TEM observations also lead to identification of the fault and analysis of its cause, which in turn lead to a marked yield improvement.     

Preparation of HPLC test solutions for organic impurities in aluminum lakes of food red no. 40 (allura red AC) and food yellow no. 5 (sunset yellow FCF)

The HPLC determination of organic impurities in Food Red No. 40 aluminum lakes (R-40Als) as directed by Japan's Specifications and Standards for Food Additives, 7th Ed. (JSFA-VII), has problems, such as reproducibility and low recovery. ICP analyses suggested that the problem was caused by the aluminum in the test solution. In the improved method for preparation of the test solution, aluminum was precipitated as a hydroxide gel by boiling with 1% aqueous ammonia. After centrifugation, the supernatant was used for the HPLC analysis of the organic impurities in the lakes. Recoveries of organic impurities were more than 85% from R-40Al spiked at the 0.1 and 1.0% levels of R-40. The proposed method was also adapted for Food Yellow No. 5 aluminum lakes.     

Multirate Sampling Method for Acceleration Control System

This paper focuses on the realization of high-performance motion control based on acceleration control. A disturbance observer is used to construct an acceleration control system. A high sampling frequency is known to be effective for improving the performance. Characteristics of acceleration control are investigated to discuss the relationship between the performance and a sampling frequency of the system. The needs for a high sampling frequency for an output are then described. Based on these considerations, a novel multirate sampling method for the acceleration control system is proposed. An output sampling period is set shorter than an input sampling period, and control calculation is executed at each output sampling period in the method. The disturbance observer is redesigned for application to the multirate system. Stability analysis is performed to verify the validity of the proposal. Feasibility of the proposed method and its influence on the performance are also verified by experimental results     

Optical Burst Switching Router With 40-,10-Gb/s Bit-Rate Transparent Contention Resolution

We report a bit-rate transparent optical burst switching (OBS) router prototype using a fast 5 times 5 PLZT [(Pb,La)(Zr,Ti)O₃ ] optical matrix switch. Dynamic switching in a two-wavelength, 2 times 2 OBS switch is demonstrated. Contention resolution using a tunable Mach-Zehnder interferometer wavelength converter for both 40- and 10-Gb/s bursts is demonstrated for the first time. Error-free operation was achieved for both bit rates under the same settings, as required in autonomous networks     

Electromyographic prosthetic hand using grasping-force-magnification mechanism with five independently driven fingers

This paper proposes an electromyographic (EMG) prosthetic hand that has five independently driven fingers, a flexion drive, and a force-magnification drive. The flexion drive allows for rapid finger motion, and the force-magnification drive allows for a firm grasp. To realize the natural feeling of control similar to that of movements with nonamputated parts, the control system includes the impedance model of human forearms and utilizes the muscle contraction level extracted from a user’s EMG signals. We experimentally verified that the maximum fingertip force of the hand exceeds 20 N, and the time required to fully close the hand by the flexion drive is 0.53 s. We also experimentally verified that in response to EMG signals, the fingers can flex smoothly and the grasping force can be modulated. Furthermore, we show that taking EMG signals as inputs makes it possible to control six operations, including ones that use the five fingers in distinctive ways.     

Design principle of micromechanical probe with an electrostatic actuator for friction force microscopy

It is important to understand friction force in micro/nano mechanical devices both at high sliding speed and with high lateral resolution. Dual-axis friction force microscopes that can provide high lateral resolution and accuracy have been proposed; however, the sliding speed is limited by the probe scan speed. While a micro mechanical probe (MMP) with an electrostatic actuator can overcome this problem, details of probe design have not been established yet. This paper presents the principle of the mechanical design for an MMP with high force sensitivity and sufficient drive force. The dimensions of the double cantilever beam control the spring constants, resonant frequencies, and drive force. The use of an actuated MMP enables accurate friction force microscopy at high sliding speeds, which is required for the design of micro/nano mechanical devices.     

Hydrolytic degradation of poly(L-lactic acid): Combined effects of UV treatment and crystallization

Amorphous and crystallized poly(L -lactic acid) (PLLA) films were prepared and the hydrolytic degradation of the ultraviolet (UV)-treated and UV-nontreated films was investigated. This study reveals that the combination of UV and thermal treatments can produce the PLLA materials having different hydrolytic degradation profiles and that the UV-irradiation in the environment will affect the design of recycling process for PLLA articles. In an early stage, the degrees of hydrolytic degradation monitored by weight loss (W_loss), number-average molecular weight (M _n), and melting temperature (T _m) were higher for the UV-treated films than for the UV-nontreated films. In a late stage, the trend traced by W_loss was reversed, and the difference in the degrees of hydrolytic degradation between the UV-treated and UV-nontreated films monitored by M _n and T _m became smaller, with the exception of the degrees of hydrolytic degradation of the amorphous films traced by T _m. Also, in the early stage, the degrees of hydrolytic degradation monitored by W_loss and M _n were higher for the crystallized films than for the amorphous films. In the late stage, this trend was reversed, with the exception of the degrees of hydrolytic degradation of the UV-treated films monitored by M _n. The main factors that determined the W_loss and T _m were the molecular weight and initial crystallinty but not the molecular structures such as terminal CC double bonds and crosslinks. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Performance of directly modulated DFB lasers in 10-Gb/s ASK, FSK,and DPSK lightwave systems

A comparison is presented of the performance of amplitude-shift-keying (ASK), frequency-shift keying (FSK), and differential-phase-shift-keying (DPSK) lightwave systems which operate at 10 Gb/s with directly modulated 1550-nm distributed feedback (DFB) laser transmitters and conventional 1310-nm dispersion-optimized fiber. Computer modeling techniques were used to accurately simulate the amplitude modulation response and the frequency modulation response of DBF lasers. The system performance is evaluated from simulated eye patterns for both direct and heterodyne detection. With the narrow-optical spectral widths of these signal formats, fiber chromatic dispersion limits up to 70 km were obtained for transmission at 1550-nm using conventional 1310-nm optimized fiber     

Numerical analysis of characteristics of microactuators driven by liquid crystals

For the purpose of developing liquid crystalline microactuators, the transient behaviors of a nematic liquid crystal between two parallel plates have been computed for various parameters such as applied voltage, the gap between the plates, and the twist and tilt angles at the plates. The Leslie-Ericksen theory has been selected as a constitutive equation. The twist angle has an effect on the induced velocity profiles; for example, the induced flow is planar at the twist angle of 0°, while the flow has an out-of-plane component when the twist angle is not 0°. Transient behaviors of shear stress acting on the plates, the flowrate, and the maximum values of the velocity, and the tilt angle between the plates have been reported. In addition, we have investigated the effects of the applied voltage, the gap between the plates, and the tilt angle at the plates on the above-mentioned values. We can develop microactuators with arbitrary characteristics by suitably controlling the applied voltage, the size of the actuators, and the director anchoring conditions.