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31.
Karima Rabaani Noureddine Boulejfen Ammar B. Kouki Fadhel M. Ghannouchi 《国际射频与微波计算机辅助工程杂志》2020,30(4)
A novel, low complexity approach for the analysis of nonuniform lossy substrate‐integrated waveguide transmission lines based on the method of moments is proposed. The approach uses frequency‐dependent basis functions derived from the structure's propagation characteristics. Two tapered structures are analyzed, fabricated, and measured to validate the proposed approach. The analytical results of the proposed approach for both structures are compared to those obtained by measurement and by three‐dimensional field simulation. Excellent agreement is observed between the three sets of results with simulation time savings on more than 98% and memory requirement reduction of more than 97%. 相似文献
32.
We studied the imaging performance of a chirped grating for a demultiplexer designed for coarse wavelength division multiplexing using a wavefront aberration analysis and the ray tracing simulation. The demultiplexer was composed of a chirped grating, cylindrical lenses, and a waveguide. The best image point and the spot shape focused by the chirped grating were effectively calculated with the wavefront aberration. We applied the aberration analysis to design a waveguide to connect branched beams to photodetectors, and we confirmed the demultiplexing performance experimentally. 相似文献
33.
Sakai K Obata K Yoshikawa M Takano R Shibata M Maeda H Mizutani A Terada K 《Drug development and industrial pharmacy》2012,38(10):1254-1261
Purpose: To design a high drug loading formulation of self-microemulsifying/micelle system. Methods: A poorly-soluble model drug (CH5137291), 8 hydrophilic surfactants (HS), 10 lipophilic surfactants (LS), 5 oils, and PEG400 were used. A high loading formulation was designed by a following stepwise approach using a high-throughput formulation screening (HTFS) system: (1) an oil/solvent was selected by solubility of the drug; (2) a suitable HS for highly loading was selected by the screenings of emulsion/micelle size and phase stability in binary systems (HS, oil/solvent) with increasing loading levels; (3) a LS that formed a broad SMEDDS/micelle area on a phase diagram containing the HS and oil/solvent was selected by the same screenings; (4) an optimized formulation was selected by evaluating the loading capacity of the crystalline drug. Aqueous solubility behavior and oral absorption (Beagle dog) of the optimized formulation were compared with conventional formulations (jet-milled, PEG400). Results: As an optimized formulation, d-α-tocopheryl polyoxyethylene 1000 succinic ester: PEG400?=?8:2 was selected, and achieved the target loading level (200?mg/mL). The formulation formed fine emulsion/micelle (49.1?nm), and generated and maintained a supersaturated state at a higher level compared with the conventional formulations. In the oral absorption test, the area under the plasma concentration-time curve of the optimized formulation was 16.5-fold higher than that of the jet-milled formulation. Conclusions: The high loading formulation designed by the stepwise approach using the HTFS system improved the oral absorption of the poorly-soluble model drug. 相似文献
34.
Yasushi Abe Kunio Matsubara Kiyoaki Sasagawa Kouki Matsuse 《IEEJ Transactions on Electrical and Electronic Engineering》2008,3(1):113-119
This paper presents a medium‐voltage inverter applying series connected general‐purpose 1.2 kV insulated gate bipolar transistors (IGBTs) as a switching device to achieve low switching losses compared to inverters applying high‐voltage IGBTs with over 3 kV rating. Gate signal synchronization, which is essential to keep the balance of collector‐emitter voltages across the IGBTs, is achieved by magnetically coupling all gate lines using a simple two‐windings transformer. In order to obtain better voltage balancing, influence of stray capacitance distribution associated with an insulating substrate in a two‐in‐one IGBT module on the voltage sharing is investigated, and an optimized layout of heat sinks for the IGBT modules is proposed. To validate some performances concerning the device losses and the voltage sharing, a 170 kVA inverter based on three 1.2 kV IGBTs connected in series is built and evaluated. The experimental results are shown. Copyright © 2007 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
35.
There have been several studies on biopolymer synthesis under hydrothermal conditions. The conventional hydrothermal methods
make it possible to synthesize only a dipeptide and short oligopeptides as well as cyclo-dimer, from amino acids. As these
studies that were applied with various quenching methods suggested the importance of quenching rate from hydrothermal conditions,
rapid quenching could avoid hydrolysis of the oligomers that had already been synthesized under hydrothermal conditions. In
this study, therefore, we designed a novel hydrothermal flow reactor adopted with adiabatic expansion cooling system from
the reason that it was thought to be one of the most rapid quenching methods. It mimics geysers, fumaroles, hot springs, and
volcanic eruptions. Once aqueous solutions of monomers were treated at high temperature and pressure, the solutions were released
into the atmosphere through an orifice to be depressurized and cooled down simultaneously with the Joule–Thomson effect. We
demonstrated oligomerization of glycine up to decamer (Gly10) by using the flow reactor, which had never been yielded with any other quenching methods. This suggests that rapid quenching
methods under non-equilibrium conditions such as adiabatic expansion cooling is an efficient way to produce long oligomers
connected by covalent bonds via dehydration condensation. 相似文献
36.
Toyoda S Suzuki Y Hattori S Yamada K Fujii A Yoshida N Kouno R Murayama K Shiomi H 《Environmental science & technology》2011,45(3):917-922
Wastewater treatment processes are believed to be anthropogenic sources of nitrous oxide (N(2)O) and methane (CH(4)). However, few studies have examined the mechanisms and controlling factors in production of these greenhouse gases in complex bacterial systems. To elucidate production and consumption mechanisms of N(2)O and CH(4) in microbial consortia during wastewater treatment and to characterize human waste sources, we measured their concentrations and isotopomer ratios (elemental isotope ratios and site-specific N isotope ratios in asymmetric molecules of NNO) in water and gas samples collected by an advanced treatment system in Tokyo. Although the estimated emissions of N(2)O and CH(4) from the system were found to be lower than those from the typical treatment systems reported before, water in biological reaction tanks was supersaturated with both gases. The concentration of N(2)O, produced mainly by nitrifier-denitrification as indicated by isotopomer ratios, was highest in the oxic tank (ca. 4000% saturation). The dissolved CH(4) concentration was highest in in-flow water (ca. 3000% saturation). It decreased gradually during treatment. Its carbon isotope ratio indicated that the decrease resulted from bacterial CH(4) oxidation and that microbial CH(4) production can occur in anaerobic and settling tanks. 相似文献
37.
Kazuo Oka Yusuke Nozawa Kouki Matsuse 《IEEJ Transactions on Electrical and Electronic Engineering》2006,1(1):108-111
This paper presents an improved method of voltage utility factor (VUF) from 50 to 86.6% for a five‐leg inverter when two induction motors are driven in vector control and in a condition where the frequencies of the two motors are not very different, and the improved method of voltage utility is theoretically shown. Many modulation methods for the five‐leg inverter have been proposed, but the voltage utility factor is 50% in these methods. The voltage utility factor of the five‐leg inverter is lower than that of the three‐leg inverter as maximum voltage utility factor of the three‐leg inverter is 100%. © 2006 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. 相似文献
38.
A computerised defect evaluation system using an advanced ultrasonic technique for shrunk-on wheels of a turbine rotor has been developed. The flaw image was reconstructed by a modified ALOK method with attention to the tip diffraction echoes of stress corrosion cracking (SCC). The results of the application of this system to the mock-up wheel with artificial slits and real SCC cracks show that this system is very useful for crack sizing and locating. 相似文献
39.
A systematic scaling approach for the modeling of high-power/large-size HBT's is presented. This approach is based on: 1) identifying and characterizing the elementary cell, and 2) modeling the input/output interconnections using the device's physical layout. The proposed approach reduces the optimization problem for the large-size device to the easier fitting of the lumped equivalent circuit of the elementary cell. It is shown that there is a good agreement between the predicted results, using the developed model, and the available measurements for different bias points. Such a modeling approach is particularly appealing for high-power applications where the large-signal characterization of large-size devices becomes a difficult task, particularly for on-wafer devices 相似文献
40.
Kouki Miyoshi Norihiro Abe Yoshihiro Tabuchi Hirokazu Taki Shoujie He 《Artificial Life and Robotics》2009,14(3):321-323
In the development of a robot, the validation of that robot with the use of real machinery takes a considerable amount of
time and money. In particular, it is difficult to validate a robot’s behavior in an unsafe place. The developers also have
to pay attention to virtual debugging. Using a program validated in VR space makes the verification of a real machine’s behavior
more efficient. In this research, we make a virtual robot walk on a road autonomously by using a program where the virtual
robot tracks a line in a virtual environment. 相似文献