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101.
FeSi2 alloys doped with Mn and Co (p-type Fe0.926Mn0.074Si2, n-type Fe0.980Co0.020Si2) were prepared by vacuum induction melting. The ingots were pulverized in a jet-mill, and the powders were granulated by spray drying method using aqueous polyvinyl alcohol (PVA) binder in order to investigate the possibility of production on a large scale. The powders granulated exhibited excellent characteristics of flowability, leading to the smooth feeding into a die cavity in compacting. The powders obtained were compacted at a pressure of 98 MPa. It was debindered at 723 K for 1 h and sintered at 1423 K for 5 h in a hydrogen atmosphere, so that the residual carbon and oxygen contents in a sintered body approached to those in the starting powder. Subsequently it was annealed at 1113 K for 100 h in an argon atmosphere, to produce the semiconducting -FeSi2 phase. The thermoelectric figures of merit (Z) for optimum p- and n-type FeSi2 are 1.75 × 10–4 (K–1) and 2.0 × 10–4 (K–1) at about 900 K, respectively, which agree roughly with those obtained by Tani and Kido for FeSi2 materials prepared by the spark plasma sintering method. It indicates that the spray drying method leading to the production on a large scale is available for the fabrication of the thermoelectric FeSi2 materials. 相似文献
102.
Koizumi H Yamamoto T Maki A Yamashita Y Sato H Kawaguchi H Ichikawa N 《Applied optics》2003,42(16):3054-3062
We will briefly review the present status of optical topography and then discuss the method of improving practicality, i.e., the signal-to-noise (S/N) ratio and the spatial resolution in observations of higher-order brain functions. The optimum wavelength pair improved the S/N ratio sixfold for deoxyhemoglobin, and new configurations of light irradiation and detection positions doubled the spatial resolution. We also report on developing application fields of optical topography. This modality will bridge the gap between natural sciences, neuroscience, and pedagogy, and show actual real-time brain activity. 相似文献
103.
Berendse F Owens SM Serlemitsos PJ Tueller J Chan KW Soong Y Krimm H Baumgartner WH Ogasaka Y Tamura K Okajima T Tawara Y Yamashita K Misaki K Kunieda H 《Applied optics》2003,42(10):1856-1866
The International Focusing Optics Collaboration for microCrab Sensitivity (InFOCmicroS) balloonborne hard x-ray telescope incorporates graded Pt/C multilayers replicated onto segmented Al foils to obtain the significant effective area at energies previously inaccessible to x-ray optics. Reflectivity measurements of individual foils demonstrate our capability to produce a mass quantity of multilayered foils with a rms roughness of 0.5 nm. The effective area of the completed mirror is 78 and 22 cm2 at 20 and 40 keV, respectively. The measured half-power diameter is 2.0 +/- 0.6 are min (90% confidence). The successful completion of this mirror demonstrates its applicability to future x-ray telescopes such as Constellation-X. 相似文献
104.
Denise Sato Yamashita Vinícius Amaral Armentano Manuel Laguna 《Journal of Scheduling》2007,10(1):67-76
We address a project scheduling problem with resource availability cost for which the activity durations are uncertain. The
problem is formulated within the robust optimization framework, where uncertainty is modeled via a set of scenarios. The proposed
solution method is based on the scatter search methodology and employs advanced strategies, such as dynamic updating of the
reference set, a frequency-based memory mechanism, and path relinking. A multistart heuristic was also developed and comparative
results are reported. The tradeoffs for risk-averse decision makers are discussed. 相似文献
105.
The thermo-emf ΔV of the touching p- and n-type Cu/Bi-Te/Cu composites with different thicknesses of t
Bi-Te and t
Cu was measured as a function of time by alternating the temperature difference ΔT at periods of T = 20, 60, 120, 240 and ∞ sec, where t
Bi-Te was varied from 0.1 to 2.0 mm and t
Cu from 0 to 4.0 mm. As a result, ΔV changes significantly with t
Bi-Te, t
Cu and T. The effective thermo-emf ΔV
eff increases significantly with an increase of 1/T and exhibited a local maximum at 1/T = 1/240 s−1. The resultant | α | and the effective temperature difference ΔT
eff were increased significantly by optimizing t
Bi-Te and t
Cu at 1/T = 1/240 s−1. The power generation ΔW
eff (= ΔV
eff2/4R
calc) estimated using the measured ΔV
eff and calculated R
calc also exhibited a local maximum at 1/240 s−1 for an optimum combination of t
Bi-Te = 0.1 mm and t
Cu = 2.0 mm, so that the maxima ΔW
eff at 1/T = 1/240 s−1 for the p- and n-type composites were 2.28 and 2.92 times higher than those obtained at 1/T = 0 s−1. This significant increase in ΔW
eff is owing to both the increase in ΔT
eff and the increase in ZT due to the increase in |α|. The power generation was thus found to be enhanced significantly by imposing the alternating
temperature gradients on touching Cu/Bi-Te/Cu composites. 相似文献
106.
The thermo-emf ΔV and current ΔI generated by imposing the alternating temperature gradients (ATG) at a period of T and the steady temperature gradient (STG) on a thermoelectric (TE) composite were measured as a function of t, where t is the lapsed time and T was varied from 60 to or ∞ s. The STG and ATG were produced by imposing steadily and alternatively a source voltage V in the range from 1.0 to 4.0 V on two Peltier modules sandwiching a composite. ΔT, ΔV, ΔI and VP oscillate at a period T and their waveforms vary significantly with a change of T, where ΔV and VP are the voltage drops in a load resistance RL and in resistance RP of two modules. The resultant Seebeck coefficient |α| = |ΔV|/ΔT of a composite under the STG was found to be expressed as |α| = |α0|(1 − Rcomp/RT), where RT is the total resistance of a circuit for measuring the output signals and Rcomp is the resistance of a composite. The effective generating power ΔWeff has a local maximum at T = 960 s for the p-type composite and at T = 480 s for the n-type one. The maximum energy conversion efficiency η of the p- and n-type composites under the ATG produced by imposing a voltage of 4.0 V at an optimum period were 0.22 and 0.23% at ΔTeff = 50 K, respectively, which are 42 and 43% higher than those at ΔT = 42 K under the STG. These maximum η for a TE composite sandwiched between two Peltier modules, were found to be expressed theoretically in terms of RP, RT, RL, αP and α, where αP and α are the resultant Seebeck coefficients of Peltier modules and a TE composite. 相似文献
107.
The core shroud and other internal component (core internals) replacements were carried out at Fukushima-Daiichi unit number three of Tokyo Electric Power Company (TEPCO) in Japan. The project is the first experience of replacement procedures that have been developed for welded core shrouds and jet pumps. The outline and experience of the project are discussed in this paper. 相似文献
108.
Hideaki Yamashita 《IIE Transactions》2001,33(10):889-895
We study automated guided vehicle systems that contain multiple vehicles. Each vehicle transports an item from a certain point to its destination. The inter-arrival time of items to each node is assumed to be independently and geometrically distributed. Each node has an infinite buffer capacity, and thus no item is lost. The deadhead time of the empty vehicle and the transportation time of the loaded vehicle are assumed to be arbitrarily distributed. We propose two empty vehicle dispatching policies, and numerically calculate the waiting time distributions of the items for each policy using a state-space reduction technique for Markov chains. Several examples are given to demonstrate the advantages and disadvantages of each policy. 相似文献
109.
A new AGC amplifier stabilising the output DC level is proposed and monolithically integrated using 1 ?m Si-bipolar IC technology. First, it is proven that the proposed AGC amplifier is about ten times superior to the conventional one in regard of output DC level stability. Next, it is confirmed that the IC, which exhibits a 720 MHz bandwidth, 39 dB maximum gain and 60 dB gain dynamic range, is feasible for 560 Mbit/s optical transmission. 相似文献
110.
Matsukawa T. Yoshida Y. Kanke M. Yamashita K. Shimada R. Nakayama T. 《Energy Conversion, IEEE Transaction on》1987,(2):262-268
A 215 MVA flywheel motor-generator is used for the toroidal field coil power supply system of the energy breakeven plasma testing facility, JT-60, which started operations in April, 1985 at JAPAN ATOMIC ENERGY RESEARCH INSTITUTE. This paper describes an outline of the flywheel motor-generator and discusses the determination of the Xd' value which affects the voltage regulation characteristic of the motor-generator and the twenty-four pulse rectifier circuit, the compensation effect of AVR for the voltage regulation characteristic, the temperature rise and stress of the flywheel which is the largest one in the world and the torsional vibration caused by a thyristor starter, together with the results of field tests. 相似文献