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排序方式: 共有1093条查询结果,搜索用时 15 毫秒
211.
Sang‐Hoon Ji Wan Pyo Hong Seung Ho Ko Kee‐Jung Lee 《Journal of heterocyclic chemistry》2006,43(3):799-801
212.
Z. B. Yan F. Duan T. N. Wong K. C. Toh K. F. Choo P. K. Chan Y. S. Chua L. W. Lee 《Heat and Mass Transfer》2013,49(7):985-990
An inclined spray chamber with four multiple nozzles to cool a 1 kW 6U electronic test card has been designed and tested in this study. The multiple inclined sprays can cover the same heated surface area as that with the multiple normal sprays but halve the volume of the spray chamber. The spray cooling system used R134a as a working fluid in a modified refrigeration cycle. It is observed that increasing mass flow rate and pressure drop across the nozzles improved the heat transfer coefficient with a maximum enhancement of 117 %, and reduced the maximum temperature difference at the heated surface from 13.8 to 8.4 °C in the inclined spray chamber with a heat flux of 5.25 W/cm2, while the heat transfer coefficient of the normal spray increased with a maximum enhancement of 215 % and the maximum temperature difference decreased from 10.8 to 5.4 °C under similar operating conditions. We conclude that the multiple inclined sprays could produce a higher heat transfer coefficient but with an increase in non-uniformity of the surface temperature compared with the multiple normal sprays. 相似文献
213.
M. Kumarasamy Raja Dingjuan Chua Yong Ping Xu 《Analog Integrated Circuits and Signal Processing》2012,70(1):57-67
An OOK transmitter in 433-MHz ISM band employing a speed-up circuit is described. The proposed speed-up circuit accelerates
the start-up of the oscillator and buffer by briefly increasing the bias currents during transmission of bit “1”. This leads
to a data rate increase from 3 to 10-Mb/s without any penalty on power consumption. The data rate can also be made adaptable
by varying the duration in which the bias current is increased. The proposed OOK transmitter is implemented in 0.35-μm CMOS
technology. The measured results show that the transmitter achieves a maximum data rate of 10-Mb/s with a dc power consumption
of 518 μW from a 1-V power supply, yielding an energy efficiency of 52 pJ/bit or 0.97 nJ/bit/mW when normalized to the output
power. This paper also derives a closed form equation which describes the transient behavior of Colpitts oscillator during
start up. 相似文献
214.
Effects of Cu2−xS phase removal on surface potential of Cu2ZnSnS4 thin-films grown by electroplating
Gee Yeong Kim Ju Ri Kim William Jo Kee Doo Lee Jin Young Kim Trang Thi Thu Nguyen Seokhyun Yoon 《Current Applied Physics》2014,14(12):1665-1668
Cu2ZnSnS4 (CZTS) has an optical band gap of 1.4–1.5 eV, which is similar to that of Cu(In,Ga)Se2 (CIGS), and a high absorption coefficient (>104 cm−1) in the visible light region. In previous reports, CIGS thin-film solar cells have been shown to improve the performance of the device since the secondary phase is removed by Potassium cyanide (KCN) etching treatment. Therefore, in this study we applied a KCN etching treatment on CZTS and measured the effects. We confirmed the removal of Cu2−xS via Kelvin probe force microscopy (KPFM) and Raman scattering spectroscopy. The effects of the experiment indicate that we can define with precision the location of the secondary phases, and therefore the control of the secondary phases will be easier and more efficient. Such capabilities could improve the solar cell performance of CZTS thin-films. 相似文献
215.
Ly Mai Emily Jessica Mitchell Kee Soon Wang Dong Lin Stuart Wenham 《Progress in Photovoltaics: Research and Applications》2014,22(12):1195-1203
The advanced semiconductor finger solar cell is a silicon wafer cell designed for industrial implementation. The concept incorporates a selective emitter with a front side grid metallisation that combines the advantages of both screen printing and plating techniques. Screen‐printed metal forms the busbars and a few thick but widely spaced fingers. The current is carried to these fingers via narrow, closely spaced, thinly plated, laser‐doped lines formed perpendicular to the fingers. This paper explains the evolution from the original semiconductor finger cell design to this advanced version and outlines the issues encountered in the process development thus far. An encouraging result of 18.5% efficiency has been achieved on a large area cell with fully industrial equipment, and several opportunities for significant improvement are identified. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
216.
Se Jin Park Jin Woo Cho Joong Kee Lee Keeshik Shin Ji‐Hyun Kim Byoung Koun Min 《Progress in Photovoltaics: Research and Applications》2014,22(1):122-128
A high band‐gap (~1.55 eV) chalcopyrite compound film (CuInGaS2) was synthesized by a precursor solution‐based coating method with an oxidation and a sulfurization heat treatment process. The film revealed two distinct morphologies: a densely packed bulk layer and a rough surface layer. We found that the rough surface is attributed to the formation of Ga deficient CuInGaS2 crystallites. Because of the high band‐gap optical property of the CuInGaS2 absorber film, a solar cell device with this film showed a relatively high open circuit voltage (~787 mV) with a power conversion efficiency of 8.28% under standard irradiation conditions. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
217.
Seung Wha Lee Sang Hoon ChaHwan Hoon Chung Kee Hwan KimSuk Keu Yeom Bo Kyung SeoBo Kyung Je Baek Hyun Kim 《Magnetic resonance imaging》2014
Purpose
To describe the patterns of bile distribution in the biliary tree, duodenum, jejunum, and stomach, and to determine the gallbladder ejection fraction (GBEF) by using functional magnetic resonance cholangiography (MRC) with gadolinium-ethoxybenzyl-diethylenetriamine penta-acetic acid (Gd-EOB-DTPA) in healthy volunteers.Materials and Methods
Forty subjects were included in this study. After conventional MRC, pre-fatty meal MRC (PRFM) was obtained at 30, 40, 50, and 60 min after contrast agent injection. Then, post-fatty meal MRC (POFM) was obtained every 10 min for 1 h. We assessed the PRFM and POFM for opacification of contrast agent in the first- and second-order intrahepatic ducts (IHDs) and the common bile duct (CBD). Contrast agent opacification in the cystic duct was assessed, and the percentage volume of contrast agent filling in the gallbladder (GB) was calculated on PRFM. We calculated the GBEF and assessed the presence of contrast agent in the GB, duodenum, jejunum, and stomach.Results
Thirty-six (90%) subjects showed grade 3 CBD opacification (visible contrast and well-defined bile duct border) on 60-min PRFM. Thirty-four (85%) subjects showed grade 3 first-order IHD opacification on 60-min PRFM. All (100%) subjects showed cystic duct opacification of contrast agent, and the average percentage volume of contrast agent filling in the GB was 68.81% ± 16.84% on 60-min PRFM. The GBEF at 30-min POFM was 35.00% ± 18.26%. Ten (25%) subjects had no contrast agent in the stomach and small bowel on all PRFMs. Twelve (30%) subjects had contrast medium in the stomach on PRFM and/or POFM.Conclusions
Functional MRC with Gd-EOB-DTPA can allow determining the distribution of bile in the biliary tree and small intestine, as well as the GBEF. 相似文献218.
Hongwei Gao Jinghua Teng Soo Jin Chua Ning Xiang 《Applied Physics A: Materials Science & Processing》2014,115(2):487-490
Coupling effect of surface plasmon (SP) with InGaAs/GaAs QW emission is demonstrated experimentally. The SP resonance is generated by disordered arrays of Au nanodisks on the InGaAs/GaAs QW surface. More than twofold enhancement in QW PL is observed. Theoretical simulations also indicated that the disordered arrays of Au structures enlarged the cone angle for which light can be radiated out. The larger angle enhances the PL intensity. 相似文献
219.
de Prinse Thomas Klantsataya Elizaveta Tsiminis Georgios Payten Thomas Moffatt Jillian Kee Tak W. Spooner Nigel A. 《Journal of fluorescence》2022,32(3):1051-1057
Journal of Fluorescence - Acetone and butanone were seen to emit blue light around 450 nm when excited in the green by a high intensity pulsed laser. The pathway of this anti-Stokes... 相似文献
220.
This paper proposes a simple geometrical ray approach to calibrate the extrinsic parameters of the virtual cameras and solve the stereo correspondence problem of the single-lens bi-prism stereovision system. Each images captured using this system can be divided into two sub-images which are generated by two virtual cameras due to the refraction through the bi-prism. This stereovision system is equivalent to the conventional two camera system and the two captured sub-images provide disparity which can be used for depth recovery. The virtual cameras will be calibrated geometrically and the correspondence problem of this system will be solved by applying epipolar geometry constraint on the generated virtual cameras instead of the real CCD camera. Experiments are conducted to validate the proposed method and the results are compared to the conventional approach to confirm its accuracy and effectiveness. 相似文献