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Synthesis and Crystal Structure of an Indenylnickel(II) NHC Complex (Ind)NiBr(1,3-bisbenzylimidazol-2-ylidene)
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作者 HU Dong-Mei SUN Hong-Mei +2 位作者 WANG Yong-Sheng SHEN Qi XUE Feng 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2006年第10期1255-1259,共5页
The complex (Ind)NiBr(1,3-bisbenzylimidazol-2-ylidene) (Ind = indenyl) 1 has been prepared in ca. 65% yield via the reaction of (Ind)2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at... The complex (Ind)NiBr(1,3-bisbenzylimidazol-2-ylidene) (Ind = indenyl) 1 has been prepared in ca. 65% yield via the reaction of (Ind)2Ni with an equivalent of 1,3-bis-benzylimidazolium bromide in THF/CH2Cl2 at 45℃, supported by elemental analysis, NMR spectroscopy and X-ray crystal determination. The crystal belongs to the triclinic system, space group Pi with a = 7.072(1), b = 11.264(2), c = 14.541(3)°A, α = 102.21(3),β = 93.44(3),γ = 90.81(3)°, V = 1129.7(4)°A^3, Z = 2, Mr = 502.08, Dc = 1.476 g/cm^3, F(000) = 512, μ= 2.642 mm^-1, R = 0.0490 and wR = 0.1137 for 3913 observed reflections (I〉 2σ(I)). The center nickel atom is coordinated by a bromide ligand, a carbene carbon and three carbon atoms of the five-membered indenyl group to form either a highly distorted square pyramid or a highly distorted square plane. 展开更多
关键词 nickel complex indenyl ligand N-heterocyclic carbene
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HOW THE CPC SEIZES MODERNITY The functionality of the Communist Party of China(CPC)is far from outdated and directly drives China’s embrace of tomorrow
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作者 Zheng Yongnian 《China Report ASEAN》 2021年第7期28-31,共4页
Former Chinese leader Deng Xiaoping was known as the chief architect of China’s reform and opening-up drive,and his inspection tour of southern China in 1992 ushered in a new chapter of history characterized by“thre... Former Chinese leader Deng Xiaoping was known as the chief architect of China’s reform and opening-up drive,and his inspection tour of southern China in 1992 ushered in a new chapter of history characterized by“three sustainables”:sustainable economic development,sustainable social stability,and sustainable institutional support and leadership.Fundamentally,the“three sustainables”deftly balanced relationships among economic,social,and political entities.Enterprises represent economic entities,the people are the social entity,and the CPC is the political entity.How exactly has the CPC promoted the modernity of China? 展开更多
关键词 CPC dated sustainable
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Broad-bandwidth and low-loss metamaterials:theory, design and realization
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作者 李乐伟 姚海英 +1 位作者 吴群 陈志宁 《Journal of Zhejiang University-Science A(Applied Physics & Engineering)》 SCIE EI CAS CSCD 2006年第1期5-23,共19页
In this paper, we summarize some recent activities in the field of metamaterial research at the National University of Singapore (NUS). Integral equations are applied for electromagnetic modelling of supernatural mate... In this paper, we summarize some recent activities in the field of metamaterial research at the National University of Singapore (NUS). Integral equations are applied for electromagnetic modelling of supernatural materials. Some special charac- teristics of the metamaterials are shown. Moreover, quasi-static Lorentz theory and numerical method (i.e., the method of moments for solving the electric field integral equation) and the transmission line theory are both presented to obtain the effective consti- tutive relations of metamaterials, respectively. Finally, feasibility of fabricating metamaterials based on analysis of equivalent transmission line model in the microwave spectrum and even higher is also shown and correspondingly some broad-bandwidth and low-loss metamaterial structures are designed and synthesized. 展开更多
关键词 METAMATERIALS Electric field integral equation (EFIE) Transmission line theory (TLT) Quasi-static Lorentz theory
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EMERGING FORMS OF SUSTAINABLE URBANISM: CASE STUDIES OF VAUBAN FREIBURG AND SOLARCITY LINZ
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作者 Thomas Schroepfer Limin Hee 《Journal of Green Building》 2008年第2期67-76,共10页
This study is an ongoing interdisciplinary collaboration, which discusses possible emerging forms of sustainable urbanismin the 21st century. The idea of sustainable urbanism is examined in this paper in more than env... This study is an ongoing interdisciplinary collaboration, which discusses possible emerging forms of sustainable urbanismin the 21st century. The idea of sustainable urbanism is examined in this paper in more than environmental andecological aspects, to highlight the emergent forms of urbanism based on new paradigms that inform on the shape ofcities to come. The two case studies discussed embody complex topics of design, dwelling, community in space, buildingtechnologies, environmental strategies, as well as models of affordability. At the same time, new trajectories in thedevelopment of sustainable urban housing are explored. It is based on the following case studies:Case Study 1: The new city district of Vauban Freiburg, in Germany, describes the guiding principles and theirimplementation in the planning and design of this new major development: Vauban comprises 2,000 homes to house5,000 people, as well as business units to provide about 500 to 600 jobs.Case Study 2: solarCity Linz, in Austria, currently comprises about 1,300 homes and 3,000 inhabitants. It wasdesigned as a fl agship development for renewable energies in urban design and includes projects by architects likeFoster and Partners, Richard Rogers, and Thomas Herzog. Construction time of the nucleus of solarCity took placefrom 1995 to 2005. 展开更多
关键词 sustainable cities emergent forms of urbanism renewable energy
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The Chinese Model of Development: An International Perspective 被引量:1
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作者 Cheng Yung-nien 《Social Sciences in China》 2010年第2期44-59,共16页
With the success of China's reform and opening up, increasing attention has been paid to the Chinese model of development both in China and abroad. However, in studying the Chinese model, many scholars, particularly ... With the success of China's reform and opening up, increasing attention has been paid to the Chinese model of development both in China and abroad. However, in studying the Chinese model, many scholars, particularly Western ones, have avoided studying China's political model. Instead, they have conceptualized the Chinese model of development as a matter of purely economic success. Actually, it is extremely hard to understand the Chinese economic model without discussing the Chinese political model, because it is China's political model that has driven the success of its economic model. Many underdeveloped countries face the grave challenge of building a stable political and social structure. There can be no doubt that the political and economic implications of the Chinese model of development provide a valuable lesson in this respect. 展开更多
关键词 the Chinese model political model economic model social reform
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生育和不育男性精液维生素B_(12)、叶酸、活性氧和精子质量的比较 被引量:6
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作者 陈起萱 VNg +4 位作者 梅节 SEChia SKTay 凌文华 CNOng 《卫生研究》 CAS CSCD 北大核心 2001年第2期80-82,共3页
为了探讨精液维生素 B1 2 (VB1 2 )、叶酸和活性氧 (ROS)对精子质量和生殖功能的影响。收集成年男性不育者 44名 (不育组 )和经证实配偶已怀孕的健康成年男性 176名 (生育组 )的精液 ,根据 WHO推荐方法检测精子质量指标 ,并测定精液 VB1... 为了探讨精液维生素 B1 2 (VB1 2 )、叶酸和活性氧 (ROS)对精子质量和生殖功能的影响。收集成年男性不育者 44名 (不育组 )和经证实配偶已怀孕的健康成年男性 176名 (生育组 )的精液 ,根据 WHO推荐方法检测精子质量指标 ,并测定精液 VB1 2 、叶酸和 ROS水平。结果显示二组 VB1 2 和叶酸没有显著性差异 (P>0 .0 5 ) ,不育组 ROS和形态异常精子都显著高于生育组 (P<0 .0 1) ,ROS与精子形态异常呈正相关 (P<0 .0 1) ,VB1 2 和叶酸与 ROS均呈负相关 (P<0 .0 1)。结论认为精液 ROS升高 ,可能促使精子形态异常 ,从而影响男性生殖功能。 展开更多
关键词 维生素R12 叶酸 活性氧 精子质量 男性不育症 精液
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中国地方品种鸡白细胞介素2基因的克隆及遗传进化分析(英文) 被引量:2
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作者 周继勇 陈吉刚 +1 位作者 王金勇 JIMMY K WANG 《生物化学与生物物理进展》 SCIE CAS CSCD 北大核心 2003年第3期384-389,共6页
鸡白细胞介素 2 (chIL 2 )是近年来新发现的一类细胞因子 .根据Sundick等发表的鸡IL 2基因序列设计一对特异性引物 ,从ConA体外激活的脾淋巴细胞中提取mRNA ,通过RT PCR方法分别扩增和克隆了我国仙居鸡、丝羽乌骨鸡两个地方品种和艾维... 鸡白细胞介素 2 (chIL 2 )是近年来新发现的一类细胞因子 .根据Sundick等发表的鸡IL 2基因序列设计一对特异性引物 ,从ConA体外激活的脾淋巴细胞中提取mRNA ,通过RT PCR方法分别扩增和克隆了我国仙居鸡、丝羽乌骨鸡两个地方品种和艾维茵商品肉鸡IL 2cDNA .仙居鸡、丝羽乌骨鸡和艾维茵商品肉鸡IL 2基因的编码区均由 42 9nt组成 ,编码一个由 143个氨基酸组成的前体蛋白 .基因 5′端含有 17个核苷酸 ,3′端含有 2 85个核苷酸组成的非编码区 ,3′ UTR中含有 5个重复的“ATTTA”序列 .编码蛋白氨基酸与来自GenBank的Kestrel、Obese和SC品系的来杭鸡比较 ,氨基酸的突变主要发生在 2 8~ 3 2位 .而这一区域仙居鸡和丝羽乌骨鸡的编码氨基酸序列与Kestrel来杭鸡相同 ,艾维茵商品肉鸡与Obese和SC来杭鸡相同 .基因系统进化树分析表明 ,仙居鸡、丝羽乌骨鸡和Kestrel来杭鸡具有很近的亲缘关系 ,艾维茵商品肉鸡与Obese和SC来杭鸡具有很近的亲缘关系 .中国的药用鸡品种———丝羽乌骨鸡在非常保守的 13 展开更多
关键词 鸡白细胞介素2 基因 克隆 遗传进化 系统进化 品种
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精液叶酸、维生素B_(12)、活性氧水平与精子质量关系研究 被引量:2
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作者 陈起萱 梅节 +3 位作者 V Ng SE Chia 凌文华 CN Ong 《营养学报》 CAS CSCD 北大核心 2001年第2期160-163,共4页
目的 : 检测人精液叶酸、维生素 B12 ( VB12 ) ,及活性氧 ( ROS)的含量 ,探讨三者与精子质量的关系。方法 : 收集经证实配偶已怀孕的新加坡籍健康成年男性 1 76名的精液 ,根据WHO推荐方法检测精子质量各项指标 ,并测定精液叶酸和 VB12... 目的 : 检测人精液叶酸、维生素 B12 ( VB12 ) ,及活性氧 ( ROS)的含量 ,探讨三者与精子质量的关系。方法 : 收集经证实配偶已怀孕的新加坡籍健康成年男性 1 76名的精液 ,根据WHO推荐方法检测精子质量各项指标 ,并测定精液叶酸和 VB12 含量及 ROS水平。结果 : 平均精液量、精子浓度和其活力都在正常范围内。而精子存活率 ( 73.0 6% )略低于 WHO标准 (≥ 75% ) ,形态异常的精子 ( 77.0 6% )高于 WHO标准 ( 70 % )。精液的叶酸含量与 ROS水平呈显著负相关 ( r=- 0 .2 5,P=0 .0 0 3) ;VB12 与 ROS呈负相关 ( r=- 0 .2 5,P=0 .0 0 2 ) ,与精子形态异常也呈负相关( r=- 0 .1 5,P=0 .0 4 8) ,但与精子浓度呈正相关 ( r=0 .31 ,P<0 .0 0 1 )。ROS与精子形态异常呈正相关 ( r=0 .2 5,P=0 .0 0 2 ) ,与精子活力也呈正相关 ( r=0 .1 9,P=0 .0 1 9)。结论 :  VB12 对精子生成和维持精子正常功能是必需的 ,ROS水平与精子功能缺陷有关 ,VB12 和叶酸可能通过降低 ROS以维持精子的正常功能。 展开更多
关键词 叶酸 维生素B12 活性氧 人体精液 精子质量
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奶粉的喷雾冷冻干燥研究 被引量:7
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作者 黄立新 周瑞君 Mujumdar A S 《化工机械》 CAS 2009年第3期219-222,共4页
研究开发了实现喷雾冷冻干燥工艺的装置,并以奶粉为物料,进行了试验研究。结果表明,料液可以在-40~-30℃实现快速冷冻,且采用该喷雾冷冻干燥装置可将干燥时间从原来真空冷冻干燥的48h缩短为10h。最后,对获得的干燥产品进行了粉体形态... 研究开发了实现喷雾冷冻干燥工艺的装置,并以奶粉为物料,进行了试验研究。结果表明,料液可以在-40~-30℃实现快速冷冻,且采用该喷雾冷冻干燥装置可将干燥时间从原来真空冷冻干燥的48h缩短为10h。最后,对获得的干燥产品进行了粉体形态的测试和分析。 展开更多
关键词 喷雾干燥 冷冻干燥 喷雾冷冻干燥
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传染性支气管炎病毒核衣壳蛋白基因变异及在大场杆菌中的表达(英文)
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作者 周继勇 丁红梅 +1 位作者 程丽琴 Jimmy Kwang 《浙江大学学报(农业与生命科学版)》 CAS CSCD 北大核心 2003年第1期1-9,共9页
核衣壳蛋白 (N)是传染性支气管炎病毒的主要结构蛋白之一。以前的研究结果显示 IBV- ZJ971毒株以引起腺胃肿大为特征 ,IBV- X和 N毒株以引起肾炎为特征。为了探讨不同组织嗜性传染性支气管炎病毒 N基因的变异 ,我们依据已发表的 IBV- Be... 核衣壳蛋白 (N)是传染性支气管炎病毒的主要结构蛋白之一。以前的研究结果显示 IBV- ZJ971毒株以引起腺胃肿大为特征 ,IBV- X和 N毒株以引起肾炎为特征。为了探讨不同组织嗜性传染性支气管炎病毒 N基因的变异 ,我们依据已发表的 IBV- Beaudette毒株 N基因的序列设计和合成引物 ,RT-PCR扩增 IBV- ZJ971、N、X和 H5 2的核衣壳蛋白基因 ,并测序、分析和在 E.coli中进行表达。结果显示 :IBV- ZJ971、N、X和 H5 2毒株的 N基因的 ORF由 12 30 bp组成 ,编码 4 0 9个氨基酸。与来源于 Gen Bank中的 IBV毒株比较 ,IBV- ZJ971、N、X和 H5 2与其它 IBV毒株的核苷酸同源性分别是 87.0 - 98.6 %、86 .6 - 99.7%、86 .3- 99.7%、87.2 % - 98.5 % ,氨基酸的同源性分别是 90 .0 - 97.8%、 90 .5 - 98.8%、 90 .0 -98.8%、 91- 98%。IBV- ZJ971毒株的 N蛋白不同于其他 IBV的独特变异是 111,117,14 2 ,171和 4 0 1位点上的氨基酸改变 ,IBV- N和 X毒株的 N蛋白不同与其它 IBV的独特变异是 4 6 ,4 8,189,190 ,2 2 0 ,2 2 3,2 36 ,2 37,2 4 0 ,2 86 ,2 99,30 1334,335 ,336 and35 1位点上的氨基酸改变。说明 IBV嗜腺胃毒株(ZJ971)和嗜肾毒株 (N和 X)的 N基因以散在的点突变为特征。将 IBV- ZJ971毒株的 N基因在 E. 展开更多
关键词 传染性支气管炎病毒 核衣壳蛋白 基因变异 基因表达 大肠杆菌
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卷积算子交换子的L^p(R^n)有界性
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作者 胡国恩 孙颀彧 《数学年刊(A辑)》 CSCD 北大核心 2001年第4期509-516,共8页
本文利用 Fourier变换估计和逼近恒等,建立由 BMO函数和卷积算子生成的交换子的Lp(Rn)有界性结果.作为一个应用,得到了关于
关键词 交换子 奇异积分 Fourier变换 卷积算子 BMO函数 逼近恒等 有界性 Fefferman型 奇异积分算子 L^P估计
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用于气体分离的含多孔材料的混合基质膜--从金属有机框架到离散分子笼 被引量:1
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作者 Ziqi Yang Zhongjie Wu +3 位作者 Shing Bo Peh Yunpan Ying Hao Yang Dan Zhao 《Engineering》 SCIE EI CAS CSCD 2023年第4期40-55,M0003,共17页
混合基质膜(MMMs)将多孔材料与聚合物基质相结合,因其互补特性和协同激活已经在气体分离领域引起了相当大的研究兴趣。多孔材料的可塑性和多样性赋予MMMs可延伸的功能和出色的分离性能。为了发挥MMMs的全部潜力,研究人员关注多孔填料与... 混合基质膜(MMMs)将多孔材料与聚合物基质相结合,因其互补特性和协同激活已经在气体分离领域引起了相当大的研究兴趣。多孔材料的可塑性和多样性赋予MMMs可延伸的功能和出色的分离性能。为了发挥MMMs的全部潜力,研究人员关注多孔填料与聚合物基质的合理匹配,以实现这些材料之间界面的增强相容性。在本文中,我们重点介绍采用不同策略将金属-有机框架(MOFs)和金属-有机笼(MOCs)与聚合物基质相结合制备MMMs的最新进展。文中进一步讨论未来MMMs发展所面临的机遇和挑战,并旨在通过合理的材料设计和选择推动MMMs的制备。 展开更多
关键词 Gas separation Metal-organic frameworks Metal-organic cages Mixed-matrix membranes Interfacial compatibility
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NETWORK-CONNECTED UAV COMMUNICATIONS 被引量:1
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作者 Yong Zeng Shi Jin +1 位作者 Qihui Wu Feifei Gao 《China Communications》 SCIE CSCD 2018年第5期I0003-I0005,共3页
Unmanned aerial vehicles(UAVs)have found fast growing applications in recent years,such as for cargo delivery,precision agriculture,aerial monitoring,video streaming,traffic control,rescue and search,and communication... Unmanned aerial vehicles(UAVs)have found fast growing applications in recent years,such as for cargo delivery,precision agriculture,aerial monitoring,video streaming,traffic control,rescue and search,and communication relaying.As the number of UAVs and their related applications grow explosively in the com- 展开更多
关键词 连接网络 通讯 UAV 精确农业 交通控制 天线 搜索
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Genome-wide Expansion and Expression Divergence of the Basic Leucine Zipper Transcription Factors in Higher Plants with an Emphasis on Sorghum 被引量:44
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作者 Jizhou Wang Junxia Zhou +3 位作者 Baolan Zhang Jeevanandam Vanitha Srinivasan Ramachandran Shu-Ye Jiang 《Journal of Integrative Plant Biology》 SCIE CAS CSCD 2011年第3期212-231,共20页
Plant bZIP transcription factors play crucial roles in multiple biological processes. However, little is known about the sorghum bZIP gene family although the sorghum genome has been completely sequenced. In this stud... Plant bZIP transcription factors play crucial roles in multiple biological processes. However, little is known about the sorghum bZIP gene family although the sorghum genome has been completely sequenced. In this study, we have carried out a genome-wide identification and characterization of this gene family in sorghum. Our data show that the genome encodes at least 92 bZIP transcription factors. These bZIP genes have been expanded mainly by segmental duplication. Such an expansion mechanism has also been observed in rice, arabidopsis and many other plant organisms, suggesting a common expansion mode of this gene family in plants. Further investigation shows that most of the bZIP members have been present in the most recent common ancestor of sorghum and rice and the major expansion would occur before the sorghum-rice split era. Although these bZlP genes have been duplicated with a long history, they exhibited limited functional divergence as shown by nonsynonymous substitutions (Ka)lsynonymous substitutions (Ks) analyses. Their retention was mainly due to the high percentages of expression divergence. Our data also showed that this gene family might play a role in multiple developmental stages and tissues and might be regarded as important regulators of various abiotic stresses and sugar signaling. 展开更多
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Build,Build,Building Sino-Philippine BRi Cooperation
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作者 Hao Nan 《China Report ASEAN》 2020年第4期46-47,共2页
This year marks the45th anniversary of theestablishment of China-Philippines diplomaticties. After some ups anddowns in recent years, thebilateral relationship hassettled into a consistentlyexpanding trend of intensiv... This year marks the45th anniversary of theestablishment of China-Philippines diplomaticties. After some ups anddowns in recent years, thebilateral relationship hassettled into a consistentlyexpanding trend of intensivedevelopment. In a 2018 statevisit to the Philippines,Chinese President Xi Jinpingjoined President Duterte inagreeing on the establishmentof comprehensive strategicpartnership between the twocountries, perceived by manyto be a sign like a rainbow afterrain.The year 2020 also bringsthe Belt and Road Initiative(BRI) to its 7th year. Inspiredby the ancient terrestrial andmaritime Silk Road, the grandinternational developmentprogram started in 2013 withtwo speeches delivered byPresident Xi in Kazakhstanand Indonesia respectivelybefore blooming across 125countries and 173 cooperationagreements and attractinginvolvement from 29international organizations.The five-pronged connectivitystrategy involving policy,facilities, trade, finance andpeople-to-people exchangehas evolved into a large-scalecooperation pattern featuringsix economic corridors androutes served by numerousports in multiple countriesas far away as Africa, LatinAmerica and the SouthPacific. 展开更多
关键词 FINANCE attracting settled
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Control of a Quadruped Robot with Bionic Springy Legs in Trotting Gait 被引量:30
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作者 Mantian Li Zhenyu Jiang +2 位作者 Pengfei Wang Lining Sun Shuzhi Sam Ge 《Journal of Bionic Engineering》 SCIE EI CSCD 2014年第2期188-198,共11页
Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the ro... Legged robots have better performance on discontinuous terrain than that of wheeled robots. However, the dynamic trotting and balance control of a quadruped robot is still a challenging problem, especially when the robot has multi-joint legs. This paper presents a three-dimensional model of a quadruped robot which has 6 Degrees of Freedom (DOF) on torso and 5 DOF on each leg. On the basis of the Spring-Loaded Inverted Pendulum (SLIP) model, body control algorithm is discussed in the first place to figure out how legs work in 3D trotting. Then, motivated by the principle of joint function separation and introducing certain biological characteristics, two joint coordination approaches are developed to produce the trot and provide balance. The robot reaches the highest speed of 2.0 m.s-1, and keeps balance under 250 Kg.m.s-1 lateral disturbance in the simulations. The effectiveness of these approaches is also verified on a prototype robot which runs to 0.83 m.s-1 on the treadmill, The simulations and experiments show that legged robots have good biological properties, such as the ground reaction force, and spring-like leg behavior. 展开更多
关键词 legged robots locomotion control quadruped robot trotting gait
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Architecture of Platonic and Archimedean polyhedral links 被引量:3
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作者 QIU WenYuan ZHAI XinDong QIU YuanYuan 《Science China Chemistry》 SCIE EI CAS 2008年第1期13-18,共6页
A new methodology for understanding the construction of polyhedral links has been developed on the basis of the Platonic and Archimedean solids by using our method of the ‘three-cross-curve and dou- ble-twist-line co... A new methodology for understanding the construction of polyhedral links has been developed on the basis of the Platonic and Archimedean solids by using our method of the ‘three-cross-curve and dou- ble-twist-line covering’. There are five classes of polyhedral links that can be explored: the tetrahedral and truncated tetrahedral links; the hexahedral and truncated hexahedral links; the dodecahedral and truncated dodecahedral links; the truncated octahedral and icosahedral links. Our results show that the tetrahedral and truncated tetrahedral links have T symmetry; the hexahedral and truncated hexahedral links, as well as the truncated octahedral links, O symmetry; the dodecahedral and truncated dodeca- hedral links, as well as the truncated icosahedral links, I symmetry, respectively. This study provides further insight into the molecular design, as well as theoretical characterization, of the DNA and protein catenanes. 展开更多
关键词 KNOT theory POLYHEDRON TRUNCATED POLYHEDRON POLYHEDRAL link DNA CATENANE protein CATENANE
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MODELING AND FORECASTING OF STOCK MARKETS UNDER A SYSTEM ADAPTATION FRAMEWORK 被引量:1
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作者 Xiaolian ZHENG Ben M.CHEN 《Journal of Systems Science & Complexity》 SCIE EI CSCD 2012年第4期641-674,共34页
This paper adopts the concept of dynamic feedback systems to model the behavior of financial markets, or more specifically, the stock market from a dynamic system point of view. Based on a feedback adaptation scheme, ... This paper adopts the concept of dynamic feedback systems to model the behavior of financial markets, or more specifically, the stock market from a dynamic system point of view. Based on a feedback adaptation scheme, the authors model the movement of a stock market index within a framework that is composed of an internal dynamic model and an adaptive filter. The output-error model is adopted as the internal model whereas the adaptive filter is a time-varying state space model with instrumental variables. Its input-output behavior, and internal as well as external forces are then identified. Special attention has also been paid to the recent financial crisis by examining the movement of Dow Jones Industrial Average (DJIA) as an example to illustrate the advantage of the proposed framework. Supported by time-varying causality tests, five influential factors from economic and sentiment aspects are introduced as the input of this framework. Testing results show that the proposed framework has a much better prediction performance than the existing methods, especially in complicated economic situations. An application of this framework is also presented with focuses on forecasting the turning periods of the market trend. Realizing that a market trend is about to change when the external force begins to exhibit clear patterns in its frequency responses, the authors develop a set of rules to recognize this kind of clear patterns. These rules work well for stock indexes from US, China and Singapore. 展开更多
关键词 Complex systems financial modeling financial systems market forecasting system economics.
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ON INVENTORY STRATEGIES OF ONLINE RETAILERS 被引量:1
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作者 Frank Y. CHEN S. H. HUM Cheryl H. SIM 《Journal of Systems Science and Systems Engineering》 SCIE EI CSCD 2005年第1期52-72,共21页
This study focuses on inventory strategies of Internet retailers (etailers). The etailer faces options of holding her own inventory or outsourcing through the third party(ies). We assess etailer inventory strategies t... This study focuses on inventory strategies of Internet retailers (etailers). The etailer faces options of holding her own inventory or outsourcing through the third party(ies). We assess etailer inventory strategies through mathematical modeling and numerical experiments. When ordering and holding her own stock, the etailer has full control of the order fulfillment process but bears the inventory-related risk. When outsourcing stock, etailer’s orders may not get an equal priority as for those of the third party’s own. Built upon simple operations research models, the numerical experiments suggest that the etailer is better off relying on others to fulfill orders if her demand (profit margin) is low, but should revert to the strategy of maintaining her own inventory if her sales volume (profit margin) is relatively high. Other factors are also investigated. These findings seem to confirm what are being practiced in the industry. 展开更多
关键词 Electronic commerce e-retailer fulfillment INVENTORY
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On Hamiltonian realization of time-varying nonlinear systems 被引量:1
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作者 WANG YuZhen Ge S. S. CHENG DaiZhan 《Science in China(Series F)》 2007年第5期671-685,共15页
This paper Investigates Hamiltonian realization of time-varying nonlinear (TVN) systems, and proposes a number of new methods for the problem. It is shown that every smooth TVN system can be expressed as a generaliz... This paper Investigates Hamiltonian realization of time-varying nonlinear (TVN) systems, and proposes a number of new methods for the problem. It is shown that every smooth TVN system can be expressed as a generalized Hamiltonian system if the origin is the equilibrium of the system. If the Jacooian matrix of a TVN system is nonsingular, the system has a generalized Hamiltonian realization whose structural matrix and Hamiltonian function are given explicitly. For the case that the Jacobian matrix is sin- gular; this paper provides a constructive decomposition method, and then proves that a TVN system has a generalized Hamiltonian realization if its Jacobian matrix has a non- singular main diagonal block. Furthermore, some sufficient (necessary and sufficient) conditions for dissipative Hamiltonian realization of TVN systems are also presented in this paper. 展开更多
关键词 generalized Hamiltonian realization dissipative Hamiltonian realization diffoemorphism structural construction
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