Speed-up of hologram generation using ClearSpeed Accelerator board

We have sped up the calculation of a computer-generated hologram by parallel computing using ClearSpeed Advance^TM Dual CSX600 PCI-X Accelerator Board by ClearSpeed Technology plc. By using two boards in parallel, our system was able to perform the calculation 50 times as fast as a personal computer.     

Development of 3‐in‐one high‐temperature superconducting cable

A three‐in‐one HTS cable has been developed. Its cable core is composed of a conductor and a shield wound with BSCCO and electrical insulation of the PPLP. The three cable cores are covered in thermal insulated stainless corrugated pipes. The BSCCO wires represent a dramatic innovation by virtue of a newly developed process named Controlled Over‐Pressure (CT‐OP). As a new cable technology, a 350‐m thermal insulation pipe was tested for 7 months to find that the life of the vacuum intensity is more than 10 years. The HTS cable with tension members was designed for installation into an underground duct. In addition, a fault current of 23 kA, 0.63 s, was applied to a sample cable with no damage to the BSCCO wires or the cable insulation. These technologies will be applied to the Albany project in the USA. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 15–24, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20577     

Growth evaluation of multiple interacting surface cracks. Part II: Growth evaluation of parallel cracks

In Part I of the current work, experiments on fatigue crack growth from notches and crack growth simulation for a coalesced crack with re-entrant portion were conducted. It was revealed that the growth rate in area is the same for the same applied stress and area of crack face. The main conclusion was that a crack with a re-entrant portion can be replaced with a semi-elliptical crack of the same area for the growth prediction. In this study, the influence of the interaction on the growth of semi-elliptical/semi-circular surface cracks in the parallel position was investigated. The stress intensity factor for various relative positions and shapes was evaluated by finite element analyses, and the magnitude of the interaction was quantified. Then a crack growth simulation for parallel surface cracks was developed. It was revealed that the magnitude of the interaction increases continuously during the crack growth and that, for a growth prediction, the parallel surface cracks can be replaced with a single crack of the same size on the projected plane when the relative spacing is close enough. It was concluded that the simulation can estimate the crack growth of interacting cracks and the replacement can be carried out when the offset distance is less than the crack depth.     

Key vacuum technology issues to be solved in evacuated tube transportation

Railway Engineering Science - Evacuated tube transportation (ETT) will be one of the ultra-large-scale vacuum application areas. This paper lists some key vacuum technology issues in ETT: (1) how...     

A heuristic‐based design of robust SMES controller taking system uncertainties into consideration

In this paper, a heuristic‐based design of robust superconducting magnetic energy storage (SMES) controller is proposed taking system uncertainties into consideration. The SMES model with active and reactive power controllers is used. In addition, the effect of SMES coil current is also included in the model. The power system and the SMES unit with the designed controller are formulated as an optimization problem. The proposed objective function considers both the damping performance index and the robust stability index. In particular, the robust SMES controller is designed to enhance the system damping performance and robustness against system uncertainties such as various load and system parameter changes. The robust stability margin is guaranteed in terms of the multiplicative stability margin (MSM). In the proposed method, the robust SMES active and reactive power controllers are designed systematically by using hybrid tabu search and evolutionary programming, so that the desired damping performance and the best obtainable MSM are acquired. Finally, the designed SMES controller is examined under different situations to evaluate and confirm the effectiveness and robustness via eigenvalue analysis and nonlinear simulations. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

煅烧条件下石灰石脱除煤气中H2S的研究

在加压流化床中测定了系统总压、水蒸气和CO2分压对CaO与H2S反应的影响。实验结果表明,在H2S分压不变的情况下,硫化反应速率随着总压的提高而减小;只有CaO硫化反应时,气相中水蒸气促进CaS产物层的熔合,阻碍硫化反应的进行;但当CaCO3煅烧反应同时进行时,水蒸气对硫化反应没有影响;CaCO3煅烧反应总是快于CaO硫化反应,CO2的不断逸出对硫化反应有促进作用。     

Influence of local stress on initiation behavior of stress corrosion cracking for sensitized 304 stainless steel

To investigate the influence of local stress on initiation behavior of stress corrosion cracking (SCC) for sensitized Type 304 stainless steel, cracking process during constant load SCC test was monitored and recorded with an in situ crack observation system. The changes in number of cracks, sum of crack length and cracked area on the specimen surface with test time were identified from the cracking images analyzed by image processing. In the SCC tests, many cracks were initiated and coalesced on the surface, and the coalescence of cracks played an important role to primary crack growth. The influence of applied stress on crack initiation was different from that on crack growth. In addition, there was a difference between influences of stress on incubation period to crack initiation and crack initiation rate. Due to these differences, a stress of 0.8S_y was thought to cause relatively many cracks compared with 0.5S_y and 1.3S_y (S_y = 200 MPa). Through quantitative estimation of distribution in local stress around a crack by finite element analysis method, it was deduced that the crack initiation is influenced not only by bulk stress applied at the end of the body, but also by local stress formed around pre-existing cracks. According to pre-existing cracks, stress enhancement accelerates the crack growth, while the stress relaxation causes the suppression of new crack initiation. Based on the experiment and analysis results, three types of growth process were suggested, which are caused by propagation itself, by new crack initiation at vicinity of the crack tip, and by coalescence of approaching cracks. Then, it was concluded that, in order to predict/simulate the cracking behavior of this SCC system, the influence of local stress on the crack initiation should be taken into account.     

Low-power wake-up receiver with subthreshold CMOS circuits for wireless sensor networks

We developed a wake-up receiver comprised of subthreshold CMOS circuits. The proposed receiver includes an envelope detector, a high-gain baseband amplifier, a clock and data recovery (CDR) circuit, and a wake-up signal recognition circuit. The drain nonlinearity in the subthreshold region effectively detects the baseband signal with a microwave carrier. The offset cancellation method with a biasing circuit operated by the subthreshold produces a high gain of more than 100 dB for the baseband amplifier. A pulse-width modulation (PWM) CDR drastically reduces the power consumption of the receiver. A 2.4-GHz detector, a high-gain amplifier and a PWM clock recovery circuit were designed and fabricated with 0.18-μm CMOS process with one poly and six metal layers. The fabricated detector and high-gain amplifier achieved a sensitivity of ?47.2 dBm while consuming only 6.8 μW from a 1.5 V supply. The fabricated clock recovery circuit operated successfully up to 500 kbps.     

Soret coefficient of a sodium germanate glass melt: Experiment,theory, and molecular dynamics simulation

The Soret effect is a diffusion phenomenon driven by a temperature gradient in a multicomponent system. This effect in condensed systems is not fully understood. Previously, we reported a theoretical model called “adjusted Kempers model” to predict the Soret coefficient in glass melts, and compared the experimental value to the theoretical value for 11Na₂O-89B₂O₃ (mol%) melts. Here, molecular dynamics calculations, as well as theoretical and experimental values, are quantitatively compared in 10Na₂O-90GeO₂ melts. We used a vertical tubular furnace to cause a temperature gradient and heated the sample from top side to reduce the natural convection. We measured the composition of 10Na₂O-90GeO₂ glass samples after 45, 90, and 180 hours of heat treatment under a temperature gradient, and estimated the steady-state Soret coefficient near 1373 K to be 1.09 × 10⁻³ K⁻¹. In addition, we calculated Soret coefficients to be 3.65 × 10⁻³ K⁻¹ and 1.85 × 10⁻³ K⁻¹ in theory and molecular dynamics calculation, respectively. The ratios between the experimental and theoretical Soret coefficients were 1.2 and 3.3 for 11Na₂O-89B₂O₃ melts and 10Na₂O-90GeO₂ melts, respectively. The difference in ratios may be attributed to the mass and size of diffusion species in the glass melts.     

In situ XAFS analysis of catalytically active cobalt species in porous clays for deep hydrodesulfurization

Mesoporous smectite-type clays containing cobalt species in lattice (MST(Co)) were prepared by a hydrothermal method and examined for hydrodesulfurization (HDS). The MST(Co) catalysts showed higher HDS activities than a commercial alumina-supported cobalt–molybdenum catalyst (Co–Mo/Al₂O₃). The active structure of MST(Co) was studied by in situ X-ray absorption fine structure and nitrogen adsorption techniques.