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991.
Neung‐Ju Lee Nam‐In Kang Won‐Jei Cho Seon‐Hee Kim Kyung‐Tae Kang Emmanuel A Theodorakis 《Polymer International》2001,50(9):1010-1015
A new monomer, exo‐3,6‐epoxy‐1,2,3,6‐tetrahydrophthalimidocaproic acid (ETCA), was prepared by reaction of maleimidocaproic acid and furan. The homopolymer of ETCA and its copolymers with acrylic acid (AA) or with vinyl acetate (VAc) were obtained by photopolymerizations using 2,2‐dimethoxy‐2‐phenylacetophenone as an initiator at 25 °C. The synthesized ETCA and its polymers were identified by FTIR, 1H NMR and 13C NMR spectroscopies. The apparent average molecular weights and polydispersity indices determined by gel permeation chromatography (GPC) were as follows: Mn = 9600 g mol?1, Mw = 9800 g mol?1, Mw/Mn = 1.1 for poly(ETCA); Mn = 14 300 g mol?1, Mw = 16 200 g mol?1, Mw/Mn = 1.2 for poly(ETCA‐co‐AA); Mn = 17 900 g mol?1, Mw = 18 300 g mol?1, Mw/Mn = 1.1 for poly(ETCA‐co‐VAc). The in vitro cytotoxicity of the synthesized compounds against mouse mammary carcinoma and human histiocytic lymphoma cancer cell lines decreased in the following order: 5‐fluorouracil (5‐FU) ≥ ETCA > polymers. The in vivo antitumour activity of the polymers against Balb/C mice bearing sarcoma 180 tumour cells was greater than that of 5‐FU at all doses tested. © 2001 Society of Chemical Industry 相似文献
992.
Seung-Han You Joon-Sang Jo Seungjin Yoo Jin-Oh Hahn Kyo Il Lee 《Journal of Mechanical Science and Technology》2006,20(11):1898-1913
This paper deals with the design of a yaw rate controller based on gain-scheduled H∞ optimal control, which is intended to maintain the lateral stability of a vehicle. Uncertain factors such as vehicle mass and cornering stiffness in the vehicle yaw rate dynamics naturally call for the robustness of the feedback controller and thus H∞, optimization technique is applied to synthesize a controller with guaranteed robust stability and performance against the model uncertainty. In the implementation stage, the feed-forward yaw moment by driver’s steer input is estimated by the disturbance observer in order to determine the accurate compensatory moment. Finally, HILS results indicate that the proposed yaw rate controller can satisfactorily improve the lateral stability of an automobile. 相似文献
993.
Chul-Ho Bae Ki-Yong Cho Tae-Yun Koo Sung-Ho Ji Myung-won Suh 《Journal of Mechanical Science and Technology》2009,23(5):1365-1373
Freeway corridors consist of urban freeways and parallel arterials for alternative use. Ramp metering in freeways and signal
control in arterials are contemporary traffic control methods that have been developed and applied in order to improve the
traffic conditions of freeway corridors. However, most existing studies have focused on either optimal ramp metering in freeways
or progressive signal strategies between arterial intersections. For efficient control of freeway corridors, ramp metering
and signal control must be considered simultaneously, as otherwise the control strategies for freeway operation may disturb
arterial traffic. On the other hand, traffic congestion and arterial bottlenecks that arise with increasing traffic volume
at peak hours and ineffective signal operation may cause problems with accessibility to freeway ramps and degrade the urban
freeway’s ability to act as a through-traffic process. This research dynamically estimates the traffic stream between an urban
freeway and its ramps according to changes in the freeway structure, traffic passing demand, and control methods due to restricted
valid information. The results are then compared with those from other methods. Finally, the integrated control in the urban
freeway traffic axis is optimized based on the expected traffic stream, by using design of experiment (DOE), neural network
(NN), and a simulated annealing algorithm.
This paper was recommended for publication in revised form by Associate Editor Kyongsu Yi
Myung-Won Suh is a professor of Mechanical Engineering. During 1986–1988, he worked in Ford motor company as researcher. During 1989–1995,
he worked in technical center of KIA motors. He took a BS Degree in Mechanical Engineering from Seoul National University
and an MS Degree in Mechanical Engineering from KAIST, South Korea. He obtained his Doctorate at University of Michigan, USA,
in 1989. His research areas include the structure and system optimization, advanced safety vehicle and reliability analysis
& optimization.
Chul-Ho Bae is a PhD candidate at Sungkyunkwan University in Suwon, South Korea. He accomplished fellowship work as researcher at Mississippi
State University, USA, in 2003 and 2005. He worked in Institute of Advanced Machinery and Technology (IMAT) as a Research
Assistant in 2004. He was a part time Lecturer in computer aided Mechanical Engineering of Ansan College of Technology, Suwon
Science College, and Osan College during 2004–2005. He took a BS Degree in Mechanical Design and an MS Degree in Mechanical
Engineering from the Sungkyunkwan University. His research interests include computer aided engineering, reliability engineering,
and optimization. 相似文献
994.
Wang-Gi Kim Jaeyoung Yang Sangsup Han Chanhwi Cho Chang-Ha Lee Hanju Lee 《Korean Journal of Chemical Engineering》1995,12(5):503-511
An experimental and theoretical study is performed for bulk separation of H2/CO2 mixture (70/30 volume %) by PSA process with zeolite 5A, a process widely used commercially in conjunction with the catalytic
steam reforming of natural gas or naphtha. For the optimized adsorption conditions of PSA, the characteristics of adsorption/desorption
characteristics have been studied through breakthrough and desorption experiments under various conditions. The purge-to-feed
ratio is important to the H2 product purity only at a long adsorption step time. H2 could be concentrated from 70% in the feed to 99.99% at H2 recovery of 67.5%. The results of all five steps in PSA are successfully predicted by the LDF model considering an energy
balance and nonlinear isotherm. For the model, the effective diffusivities (D,) are obtained separately from the uptake curves
of H2 and CO2. The Langmuir-Freundlich isotherm is used to correlate the experimental equilibrium data and is very well fitted to the results. 相似文献
995.
996.
提出一种结构新颖的压电驱动膜片式微型气泵,对其输出流量、膜片的振幅等参数进行了理论分析,在此基础上设计、制作了微型气泵样机,并进行了测试实验。这种气泵在结构上充分利用了双压电梁端部位移大的优点,并利用两根双压电梁将膜片悬起,增加了容积变化率和输出流量,并具有结构简单,功耗低,厚度小,无电磁噪音,可靠性高等优点,在微型电子器件的冷却、微型燃料电池换气等方面显示出良好的应用前景。根据实验,微型气泵的一阶固有频率约为120Hz,在谐振状态下,当驱动电压为50V时,其输出流量为192mL/min,功耗小于23mW。 相似文献
997.
In this paper, experimental studies of a decentralized neural network control scheme of the reference compensation technique applied to control a 2-degrees-of-freedom (2-DOF) inverted pendulum on an x - y plane are presented. Each axis is controlled by two separate neural network controllers to have a decoupled control structure. Neural network controllers are applied not only to balance the angle of pendulum, but also to control the position tracking of the cart. The decoupled control structure can compensate for uncertainties and cancel coupling effects. Especially, a circular trajectory tracking task is tested for position tracking control of the cart while maintaining the angle of the pendulum. Experimental result shows that position control of the inverted pendulum and cart is successful. 相似文献
998.
J. H. Lee D. H. Seo C. W. Won I. P. Borovinskaya V. I. Vershinnikov 《Journal of Materials Science》2001,36(22):5311-5314
Tungsten powder was prepared by the Self-Propagating High-Temperature Synthesis (SHS) Process of WO3-Zn mixture. Zn vapor was discovered to affect significantly the combustion parameters such as combustion temperature (T
c
), combustion velocity (U), relative mass change (m) and relative elongation (h) of the sample. These effects could be reduced by decreasing internal Ar pressure and sample density. The ZnO in the product was leached with an HCl solution. The Zinc-thermal reduction mechanism was revealed through a quenching of the sample. 相似文献
999.
为了避免用户通过"二次挖掘"才能得到有用的结果集,本文提出了一种新的约束最大频繁模式挖掘算法CSMFPMax.CSMFP-Max算法基于CFP树和对称矩阵,在挖掘过程中采用了多种剪枝策略并结合了自顶向下和自底向上的双向搜索策略,大大缩小了候选集规模,避免了不必要的条件CFP树的产生.理论分析和实验结果表明CSMFP-Max算法是一种高效的约束最大频繁模式挖掘算法,具有良好的时空效率. 相似文献
1000.
Summary Cyclic tris(ethylene terephthalate) (CTET) was separated from oligomeric extract of poly(ethylene terephthalate) by the conventional solvent separation method. The structure of CTET was characterized by differential scanning calorimetry, X-ray diffraction, and scanning electron microscopy. It is shown that the double melting behavior of meltcrystallized CTET is attributed to the morphological change created by heat-treatment. The effect of the morphological change on the crystal structure of CTET was also examined. 相似文献