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991.
Ha-Yull Chung Jiyong Park Jung-Han Kim Un-Yong Kong 《Journal of the American Oil Chemists' Society》1996,73(5):637-643
Effects of the reaction temperature, reaction time, mole ratio of fatty acid methyl esters (FAME) to sorbitol, and mole ratio
of fatty acid sodium soaps (FASS) to sorbitol on yields of sorbitol fatty acid polyester (SFPE) were examined with a response
surface methodology. The optimum reaction conditions selected with response surface analysis were as follows: reaction temperature,
144°C; reaction time, 6.65 h; mole ratio of FAME to sorbitol, 10.7∶1; and mole ratio of FASS to sorbitol, 0.77∶1. Under these
reaction conditions, the experimental yield of sorbitol fatty acid polyester (mean value: 92% range: 89–94%) obtained from
seven replications was close to the predicted value (94%) calculated from the polynomial response surface model equation.
The response surface methodology approach used in this study was able to predict the reaction conditions necessary for a high
yield of sorbitol fatty acid polyester. 相似文献
992.
A 3D micro-scale model is developed to simulate the transport and electrochemical reaction in a composite cathode. This model takes into account the details of the specific cathode microstructure such as random pore structure, active TPB (three phase boundary) site distribution, particle size and composition and their interrelationship to the charge transfer and mass transport processes. Especially, the pore structure and mass diffusion were incorporated into this model. Influence of the microsturcture parameters on the performance was investigated by numerical simulations. 相似文献
993.
Minimal valid automata (MVA) refer to valid automata models that fit a given input‐output sequence sample from a Mealy machine model. They are minimal in the sense that the number of states in these automata is minimal. Critical to system identification problems of discrete event systems, MVA can be considered as a special case of the minimization problem for incompletely specified sequential machine (ISSM). While the minimization of ISSM in general is an NP‐complete problem, various approaches have been proposed to alleviate computational requirement by taking special structural properties of the ISSM at hand. In essence, MVA is to find the minimal realization of an ISSM where each state only has one subsequent state transition defined. This paper presents an algorithm that divides the minimization process into two phases: first to give a reduced machine for the equivalent sequential machine, and then to minimize the reduced machine into minimal realization solutions. An example with comprehensive coverage on how the associated minimal valid automata are derived is also included. 相似文献
994.
Rean Der Chien Shia‐Chung Chen Ming‐Chung Lin Ping‐Hui Lee Chun‐Sheng Chen 《应用聚合物科学杂志》2003,90(11):2979-2986
Gas channel design plays a dominant role in determining the successful application of gas‐assisted injection molding. Although empirical guidelines for gas channel design have been proposed by the various equipment suppliers, quantitative criteria based on well‐designed experiments have not been reported yet. In this study, transparent polystyrene plates designed with semicircular gas channels of different radii and with rectangular gas channels of different width‐to‐height ratios were gas‐assisted‐injection‐molded to investigate the geometrical effects on gas penetration with various plate thicknesses. Plate parts designed with gas channels having four different types of cross sections but with the same section area were also examined. Molding windows and criteria for gas penetration were properly chosen so that the design rule could be defined quantitatively. The moldability index was also classified into five levels (excellent, good, fair, poor, and bad) based on the relative areas of the molding windows. From a plot of the moldability index versus the ratio of the equivalent gas channel radius to the plate thickness, we found that the ratio should be approximately greater than 2 for an appropriate molding window (fair moldability index) to be obtained. The dimensional ratio of the width to the height for rectangular gas channels also affected the moldability index under the same equivalent radius. Meanwhile, for four gas channel designs, both gas channel designs attached to the top rib provided better moldability than the other designs. This investigation offers part designers preliminary quantitative design and molding guidelines for choosing an effective gas channel design that allows the parts to be molded under an appropriate molding window so that the uncertainty in both simulation and process control can be overcame. Furthermore, this study provides a methodology for the establishment of quantitative gas channel design guidelines. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2979–2986, 2003 相似文献
995.
Performance analysis of HomePlug 1.0 MAC with CSMA/CA 总被引:1,自引:0,他引:1
Min Young Chung Myoung-Hee Jung Tae-Jin Lee Yutae Lee 《Selected Areas in Communications, IEEE Journal on》2006,24(7):1411-1420
As demands for data communications among home/personal devices in home environments increase, various types of home-networking technologies have appeared. Among them, power line communication is one of the most promising wired home-networking technologies, because the existing power line facilities can be utilized for data transmission without deploying any new physical links. HomePlug 1.0 is the most popular power line communication technology, which has been standardized by the HomePlug power line alliance, and attempts to mitigate the effect of time- and frequency-varying channels by enhanced modulation and channel coding. Although HomePlug 1.0 has undergone field trials and simulations, its analytic model and performance was only conducted for throughput under saturation conditions. We propose a new analytic model to evaluate MAC throughput and delay of HomePlug 1.0 both under saturation and under normal traffic conditions. We verify our proposed model via simulations and evaluate the performance of HomePlug 1.0. 相似文献
996.
Gye‐Hee Lee Heung‐Jin Chung Chang‐Koon Choi 《International journal for numerical methods in engineering》2003,56(3):331-350
In this paper, an adaptive analysis of crack propagation based on the error estimation by the element‐free Galerkin (EFG) method is presented. The adaptivity analysis in quasi‐static crack propagation is achieved by adding and/or removing the nodes along the background integration cells, those are refined or recovered according to the estimated errors. These errors are obtained basically by calculating the difference between the values of the projected stresses and original EFG stresses. To evaluate the performance of the proposed adaptive procedure, the crack propagation behaviour is investigated for several examples. The results of these examples show the efficiency and accuracy of the proposed scheme in crack propagation analysis. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
997.
Hee Sang Chung Wonkyoung Lee Moo-Jung Chu Yong Bae Lee Han Hyub Lee Donghan Lee 《Photonics Technology Letters, IEEE》2003,15(4):522-524
This report presents a low-noise L-band erbium-doped fiber amplifier (EDFA) with a dispersion-compensating Raman amplifier. With an optimized prestage and 1500-nm Raman-pump laser diodes, the proposed EDFA achieved an internal noise figure of less than 4.5 dB over a 33-nm flat gain bandwidth within 0.5 dB at -2 dBm of large signal input power. 相似文献
998.
Kyoung Hwan Yeo Chang Woo Oh Sung Min Kim Min Sang Kim Chang Sub Lee Sung Young Lee Sang Yeon Han Eun Jung Yoon Hye Jin Cho Doo Youl Lee Byung Moon Yoon Hwa Sung Rhee Byung Chan Lee Jeong Dong Choe Ilsub Chung Donggun Park Kinam Kim 《Electron Device Letters, IEEE》2004,25(6):387-389
Highly manufacturable partially insulated field-effect transistors (PiFETs) were fabricated by using Si-SiGe epitaxial growth and selective SiGe etch process. Owing to these technologies, pseudo-silicon-on-insulator (SOI) structures, partially insulating oxide (PiOX) under source/drain (PUSD) and PiOX under channel (PUC), could be easily realized with excellent structural and process advantages. We are demonstrating their preliminary characteristics and properties. Especially, in the PUSD PiFET, junction capacitance, leakage current, and DIBL in bulk devices could be reduced and the floating body problem in SOI devices was also cleared without any area penalty. Thus, this PiFET structure can be a promising candidate for the future DRAM cell transistor. 相似文献
999.
Yun Tu David Kingston Judy Kung Luba S. Kotlyar Bryan D. Sparks Keng H. Chung 《Petroleum Science and Technology》2006,24(3):327-338
The effectiveness of commercial oilsands separation processes relies on the water wettability of the solids. Consequently, the interaction between the mineral and organic matter types present in oilsands is of interest. In this work, we report results related to the adsorption of a pentane insoluble fraction from bitumen on kaolinite and illite, the major clay types present in oilsands. We determined adsorption from toluene solution by illite and kaolinite and use a combination of spectroscopic techniques to probe the organic coated clay surfaces to different depths. The results are compared with similar data for equivalent natural fractions from oilsands. 相似文献
1000.
Shin K. Weize Xiong Chung Yeung Cho Cleavelin C.R. Schulz T. Schruefer K. Patruno P. Smith L. Tsu-Jae King Liu 《Electron Device Letters, IEEE》2006,27(8):671-673
The impact of stress induced by biaxial mechanical bending on multiple-gate FET (MuGFET) performance is studied. For relatively low levels of bending-induced surface strain (/spl sim/ 0.1%), significant enhancements in the driving current can be achieved and maintained with gate-length scaling. This makes package strain a potentially attractive approach to enhancing MuGFET-based CMOS performance at low cost. For bending-induced strain, the enhancements in electron mobility and [110] hole mobility are well predicted by the piezoresistance model using the coefficients for bulk-Si, but the impact of stress on (100) hole mobility is more complex. 相似文献