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
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
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
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
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
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
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
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
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
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
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
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
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
基金This work was supported by the National Natural Science Foundation of China (No. 20272040) and the Key Lab. of Organic Synthesis of Jiangsu Province
文摘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.
文摘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?
文摘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.
文摘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.
文摘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.
基金Funds supported by National Natural Science Foundation of China (project No.30 0 70 5 70 ) Natural ScienceFoundation of Zhejiang Province(project No.3994 11) the Science and Technology Commission of Zhejiang Province(projectNo.99110 2 0 30 )
基金supported by the Ministry of Education,Singapore(MOE2019-T2-1-093 and MOE-T2EP10122-0002)the Energy Market Authority of Singapore(EMA-EP009-SEGC-020)+1 种基金the Agency for Science,Technology and Research(U2102d2004 and U2102d2012)the National Research Foundation Singapore(NRF-CRP26-2021RS-0002).
文摘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-
基金supported by Strategic Research Program from Temasek Life Sciences Laboratory in Singapore
文摘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.
文摘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.
基金Acknowledgment This work was supported by the National Hi-tech Research and Development Program of China (863 Program, Grant No. 2011AA040701), and the National Natural Science Foundation of China (No. 61375097, No. 61175107)
文摘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.
基金Supported by the National Natural Science Foundation of China (Grant Nos. 20173023 and 90203012) Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20020730006)
文摘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.
文摘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.
文摘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.
基金Supported by the National Natural Science Foundation of China (Grant No. 60474001)the Research Fund of the Doctoral Program of ChineseHigher Education (Grant No. 20040422059)the Natural Science Foundation of Shandong Province (Grant No. Y2006G10)
文摘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.