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131.
A new technique for designing linear phase quadrature mirror filters (QMF) filters is proposed. These filters have the frequency responses of sharp and symmetrical transition characteristics, and the properties of perfect reconstruction and simple implementation.<> 相似文献
132.
Sangook Jun Yong-Hee Jeon Joohyun Rho Dong-ho Lee 《Journal of Mechanical Science and Technology》2006,20(1):133-146
Collaborative optimization(CO) is a multi-level decomposed methodology for a large-scale multidisciplinary design optimization(MDO).CO is known to have computational and organizational advantages. Its decomposed architecture removes a necessity of direct communication
among disciplines, guaranteeing their autonomy. However,CO has several problems at convergence characteristics and computation time. In this study, such features are discussed and
some suggestions are made to improve the performance ofCO. Only for the system level optimization, genetic algorithm is used and gradient-based method is used for subspace optimizers.
Moreover, response surface models are replaced as analyses in subspaces. In this manner,CO is applied to aero-structural design problems of the aircraft wing and its results are compared with the multidisciplinary
feasible (MDF) method and the original CO. Through these results, it is verified that the suggested approach improves convergence
characteristics and offers a proper solution. 相似文献
133.
134.
135.
Jee-Young?ShinEmail author Young-Seok?Son Moo-Geun?Kim Jae-Soo?Kim Yong-Joon?Jeon 《Journal of Mechanical Science and Technology》2003,17(11):1746-1755
Operating characteristics of a triple pressure reheat HRSG are analyzed using a commercial software package (Gate Cycle by
GE Enter Software). The calculation routine determines all the design parameters including configuration and area of each
heat exchanger. The off-design calculation part has the capability of simulating the effect of any operating parameters such
as power load, process requirements, and operating mode, etc., on the transient performance of the plant. The arrangement
of high-temperature and intermediate-temperature components of the HRSG is changed, and its effect on the steam turbine performance
and HRSG characteristics is examined. It is shown that there could be a significant difference in HRSG sizes even though thermal
performance is not in great deviation. From the viewpoint of both economics and steam turbine performance, it should be carefully
reviewed whether the optimum design point could exist. Off-design performance could be one of the main factors in arranging
components of the HRSG because power plants operate at various off-design conditions such as ambient tempera-ture and gas
turbine load, etc. It is shown that different heat exchanger configurations lead to different performances with ambient temperature,
even though they have almost the same performances at design points. 相似文献
136.
We have fabricated refractive sapphire microlenses and characterized their properties for what we believe to be the first time. We use thermally reflown photoresist lenslet patterns as a mask for chlorine-based dry etch of sapphire. Pattern transfer to the mechanically hard and chemically inert sapphire substrate is made possible by an inductively coupled plasma etch system that supplies a high-density plasma gas. Processed sapphire microlenses exhibit properties close to the ideal and operate nearly in the diffraction limit. 相似文献
137.
The main purpose of this study is to find out the best solution of the vehicle routing problem simultaneously considering heterogeneous vehicles, double trips, and multiple depots by using a hybrid genetic algorithm. This study suggested a mathematical programming model with a new numerical formula which presents the amount of delivery and sub-tour elimination. This model gives an optimal solution by using OPL-STUDIO(ILOG CPLEX). This study also suggests a hybrid genetic algorithm (HGA) which considers the improvement of generation for an initial solution, three different heuristic processes, and a float mutation rate for escaping from the local solution in order to find the best solution. The suggested HGA is also compared with the results of a general genetic algorithm and existing problems suggested by Eilon and Fisher. We found better solutions rather than the existing genetic algorithms. 相似文献
138.
I. C. Kong M. Kim K. S. Ko J. G. Kim C. W. Jeon A. Bhandari 《Canadian Metallurgical Quarterly》2007,133(7):772-776
This paper describes the application of a genetically engineered microorganism, Pseudomonas putida mt-2 KG1206, to monitor toluene analogs in groundwater collected from petroleum hydrocarbon contaminated sites. KG1206 contains the intact TOL plasmid and a second plasmid with the Pm-lux gene allowing it to produce bioluminescence in the presence of toluene analogs and their derivatives such as toluene, xylenes, and m-toluate. The simple bioluminescence assay consisted of mixing one volume of groundwater sample with four volumes of broth culture followed by bioluminescence measurement after 30?min. The maximum bioluminescent response with pure chemicals followed the order: m-methyl benzyl alchohol>m-toluate>toluene>m-xylene>benzoate>p-xylene>o-xylene. The bioluminescence production was well correlated to the m-toluate concentrations (R2>0.97) in field samples, with concentrations predicted from the bioassay falling within 75–158% of true concentration. However, no strong correlation was observed between the bioluminescence intensity and the total inducer concentration in the groundwater. Results from this study demonstrate the potential of using recombinant bioluminescent bacteria as a rapid and simple tool for monitoring specific pollutants at contaminated sites. 相似文献
139.
Seung-Chul Lee Young-Deuk Jeon Jong-Kee Kwon Jongdae Kim 《Solid-State Circuits, IEEE Journal of》2007,42(12):2688-2695
This paper describes a 10-bit 205-MS/s pipeline analog-to-digital converter (ADC) for flat panel display applications with the techniques to alleviate the design limitations in the deep-submicron CMOS process. The switched source follower combined with a resistor-switch ladder eliminates the sampling switches and achieves high linearity for a large single-ended input signal. Multistage amplifiers adopting the complementary common-source topology increase the output swing range with lower transconductance variation and reduce the power consumption. The supply voltage for the analog blocks is provided by the low drop-out regulator for a high power-supply rejection ratio (PSRR) under the noisy operation environment. The pipeline stages of the ADC are optimized in the aspect of power consumption through the iterated calculation of the sampling capacitance and transconductance. The ADC occupies an active area of 1.0 mm2 in a 90-nm CMOS process and achieves a 53-dB PSRR for a 100-MHz noise tone with the regulator and a 55.2-dB signal-to-noise-and-distortion ratio for a 30-MHz 1.0-VPP single-ended input at 205 MS/s. The ADC core dissipates 40 mW from a 1.0-V nonregulated supply voltage. 相似文献
140.
A 9‐bit 80‐MS/s CMOS pipelined folding analog‐to‐digital converter employing offset‐canceled preamplifiers and a subranging scheme is proposed to extend the resolution of a folding architecture. A fully differential dc‐decoupled structure achieves high linearity in circuit design. The measured differential nonlinearity and integral nonlinearity of the prototype are ×0.6 LSB and ×1.6 LSB, respectively. 相似文献