Under the background of urban renewal, this paper re-explores the tourism development modeof Nanluoguxiang historical and cultural block based on online review data, and puts forward correspondingdevelopment strategie...Under the background of urban renewal, this paper re-explores the tourism development modeof Nanluoguxiang historical and cultural block based on online review data, and puts forward correspondingdevelopment strategies. As a cultural label of a city, historical and cultural blocks should be updated first inorder to achieve sustainable development. By using multi-source big data review and qualitative researchmethods, the perception evaluation of tourists in Nanluoguxiang is obtained, and the shortcomings ofcurrent tourism development mode are analyzed. Furthermore, corresponding improvement strategies andsuggestions are put forward, in order to provide some effective ideas for the sustainable development ofhistorical and cultural blocks in the future.展开更多
Public administration slogans include oral and written slogans which made by governments at all levels according to the policy or administration under the propagation tasks. T he purpose is to enhance propaganda effec...Public administration slogans include oral and written slogans which made by governments at all levels according to the policy or administration under the propagation tasks. T he purpose is to enhance propaganda effects by repeating the same concepts and objectives. While the democratic awareness in public discourses is keep growing,there are some surveys on the quality of public administration slogans. In order to improve the quality of public administration slogans,governments in Anhui Province should organize professionals and pay closely attention to the guidance of policy before they sort,edit,produce and release public administration slogans.展开更多
Two 1D coordination polymers Cu2I(C6N3H4)2(1) and CuⅡ(C6N3H4)2·H2O(2) based on benzotriazole(Bta) were hydrothermally synthesized by controlling the crystallization temperature.Single-crystal X-ray dif...Two 1D coordination polymers Cu2I(C6N3H4)2(1) and CuⅡ(C6N3H4)2·H2O(2) based on benzotriazole(Bta) were hydrothermally synthesized by controlling the crystallization temperature.Single-crystal X-ray diffraction(XRD) analyses reveal that compound 1 is a 1D tubular structure constructed from two types of 1D chains {―Cu―N=N―N―} n,where the Cu(I) ions adopt linear,triangular,and tetrahedral coordination modes to connect two types of Bta ligands via π-π interaction inside the tubular-like chain.For compound 2,the Cu(Ⅱ) ions assume a quadrilateral coordination mode linking to the Bta ligands to give 1D straight chains,which stacks through π-π interactions to construct a 2D layer structure.Further characterizations including elemental analyses,infrared IR spectra,thermogravimetric(TG) analyses and luminescence properties have been done.展开更多
Walking is a complex task which includes hundreds of muscles, bones and joints working together to deliver smooth movements. With the complexity, walking has been widely investigated in order to identify the pattern o...Walking is a complex task which includes hundreds of muscles, bones and joints working together to deliver smooth movements. With the complexity, walking has been widely investigated in order to identify the pattern of multi-segment movement and reveal the control mechanism. The degree of freedom and dimensional properties provide a view of the coordinative structure during walking, which has been extensively studied by using dimension reduction technique. In this paper, the studies related to the coordinative structure, dimensions detection and pattern reorganization during walking have been reviewed. Principal component analysis, as a popular technique, is widely used in the processing of human movement data. Both the principle and the outcomes of principal component analysis were introduced in this paper. This technique has been reported to successfully reduce the redundancy within the original data, identify the physical meaning represented by the extracted principal components and discriminate the different patterns. The coordinative structure during walking assessed by this technique could provide further information of the body control mechanism and correlate walking pattern with injury.展开更多
In China,the vertical coordination development mode of agricultural products can be divided into traditional market-oriented transaction mode with fluctuation according to market conditions,made-to-order on the basis ...In China,the vertical coordination development mode of agricultural products can be divided into traditional market-oriented transaction mode with fluctuation according to market conditions,made-to-order on the basis of farmer organization,company leading cooperative mode,share or shareholding cooperative mode,and vertical integration mode. There are differences in coordination characteristics,advantages and disadvantages,and adaptability between different modes. Traditional vertical coordination mode is transforming and upgrading to close and high-efficient mode. In this process,it is influenced by factors such as cost-benefit balance between farmers and agricultural product processing enterprises,special use of agricultural product processing,structure of agricultural product industry chain,and action of local government.展开更多
In this paper, we conduct research on the current condition of college tourism personnel training mode and vocational education reforms. Paying attention to the current social development innovation spirit, how to mak...In this paper, we conduct research on the current condition of college tourism personnel training mode and vocational education reforms. Paying attention to the current social development innovation spirit, how to make students possess the necessary ability to innovate, is this the prime problem of the education. A lot of highly educated personnel in order to better adapt to social development and changes, constantly to learn knowledge, also has the characteristics of vocational college students. Our research combines the characteristics of the college tourism personnel training mode with the education reform which will enhance the performance of the teaching process.展开更多
One-photon absorption and two-photon absorption(TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polar...One-photon absorption and two-photon absorption(TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polarizable continuum model.The different isomer and coordination geometry of each probe are taken into account. Special emphasis is placed on the effects of isomerism and the coordination mode on the optical properties. The intra-molecular charge transfer(ICT)properties are specified by natural bond orbital charge analysis. It is shown that the isomerism has non-negligible effects on TPA properties of free ligands. It is found that both the TPA wavelength and the cross section are highly dependent on the coordination mode. When the zinc ion connects with the picolyl unit in the middle of a ligand, the zinc complex has a large TPA intensity in a long wavelength range due to the increased ICT mechanism.展开更多
The properties of one-photon absorption(OPA),emission and two-photon absorption(TPA)of a bipyridine-based zinc ion probe are investigated employing the density functional theory in combination with response functions....The properties of one-photon absorption(OPA),emission and two-photon absorption(TPA)of a bipyridine-based zinc ion probe are investigated employing the density functional theory in combination with response functions.The responsive mechanism and coordination mode effect are explored.The structural fluctuation is illustrated by molecular dynamics simulation.The calculated OPA and emission wavelengths of the probe are consistent with the experimental data.It is found that the red-shift of OPA wavelength and the enhancement of TPA intensity are induced by the increased intra-molecular charge transfer mechanism upon metal binding.The structural fluctuation could result in the blue-shift of TPA wavelength and the decrease of the TPA cross section.The TPA properties are quite different among the zinc complexes with different coordination modes.The TPA wavelength of the complexes with two ligands is close to that of the probe,which is in agreement with the experimental observation.展开更多
In this paper, we conduct research on the professional development mode of primary and the secondary school English teachers. Teacher training is an effective way to promote the teachers’ professional development tha...In this paper, we conduct research on the professional development mode of primary and the secondary school English teachers. Teacher training is an effective way to promote the teachers’ professional development that is an important content of teacher education, and teachers’ pre-service training, entry education together constitute a complete content of teacher education, teacher training, of course and is also the need of teachers’ lifelong learning, for the national government attached great importance to teachers’ training work. English teaching is a kind of creative and complicated work, and whole teaching activity involves teachers, students, teaching objective and the teaching content, teaching means and teaching links such as basic elements. This paper proposes the novel perspective of the professional development mode for teachers that will be meaningful.展开更多
In order to better carry out research on education and teaching,the author consulted relevant literature on blended teaching mode from 2011-2021 through CNKI,Web of Science and other websites,summarized and analyzed t...In order to better carry out research on education and teaching,the author consulted relevant literature on blended teaching mode from 2011-2021 through CNKI,Web of Science and other websites,summarized and analyzed the research status of blended teaching mode,in order to lay a good foundation for studying blended teaching mode in course teaching.展开更多
A rigid flexible coupling physical model which can represent a flexible spacecraft is investigated in this paper. By applying the mechanics theory in a non-inertial coordinate system,the rigid flexible coupling dynami...A rigid flexible coupling physical model which can represent a flexible spacecraft is investigated in this paper. By applying the mechanics theory in a non-inertial coordinate system,the rigid flexible coupling dynamic model with dynamic stiffening is established via the subsystemmodeling framework. It is clearly elucidated for the first time that,dynamic stiffening is produced by the coupling effect of the centrifugal inertial load distributed on the beamand the transverse vibration deformation of the beam. The modeling approach in this paper successfully avoids problems which are caused by other popular modeling methods nowadays: the derivation process is too complex by using only one dynamic principle; a clearly theoretical explanation for dynamic stiffening can't be provided. First,the continuous dynamic models of the flexible beamand the central rigid body are established via structural dynamics and angular momentumtheory respectively. Then,based on the conclusions of orthogonalization about the normal constrained modes,the finite dimensional dynamic model suitable for controller design is obtained. The numerical simulation validations showthat: dynamic stiffening is successfully incorporated into the dynamic characteristics of the first-order model established in this paper,which can indicate the dynamic responses of the rigid flexible coupling system with large overall motion accurately,and has a clear modeling mechanism,concise expressions and a good convergence.展开更多
A novel nitro-coordinated potassium compound [K(Htdc)(H_2O)]_n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an inf...A novel nitro-coordinated potassium compound [K(Htdc)(H_2O)]_n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an infinite K-O ladder-shaped chain, which is connected through carboxyl and unusual nitro-coordination of Htdc– anion. Then the 2D layers are further extended by intermolecular hydrogen-bonding to form a three-dimensional(3D) supramoleculalr network. Variable temperature powder X-ray diffractions, thermogravimetric analysis and nuclear magnetic resonance studies exhibit that the compound has a thermal-induced decarboxylative behavior.展开更多
A new intelligent control method for welding positioner is proposed. Applying an improved fuzzy controller and a variable PID controller, a two-mode intelligent coordinating controller ( TMICC ) is designed on basis o...A new intelligent control method for welding positioner is proposed. Applying an improved fuzzy controller and a variable PID controller, a two-mode intelligent coordinating controller ( TMICC ) is designed on basis of fuzzy logic and rules. The simulation and experimental results show that this control system can obtain better dynamic and static characteristics.展开更多
The rigid flexible coupling system with a mass at non-tip position of the flexible beam is studied in this paper. Using the theory about mechanics problems in a non-inertial coordinate sys- tem, the dynamic equations ...The rigid flexible coupling system with a mass at non-tip position of the flexible beam is studied in this paper. Using the theory about mechanics problems in a non-inertial coordinate sys- tem, the dynamic equations of the rigid flexible coupling system with dynamic stiffening are estab- lished. It is clearly elucidated for the first time that, dynamic stiffening is produced by the coupling effect of the centrifugal inertial load distributed on the beam and the transverse vibration deformation of the beam. The modeling approach in this paper successfully solves problems of popular modeling methods nowadays: the derivation process is too complex by using only one dynamic principle; a clearly theoretical mechanism for dynamic stiffening can' t be offered. First, the mass at non-tip po- sition is incorporated into the continuous dynamic equations of the system by use of the Dirac lunch tion and the Heaviside function. Then, based on the conclusions of orthogonalization about the nor- mal constrained modes, the finite dimensional state space equations suitable for controller design are obtained. The numerical simulation results show that: dynamic stiffening is included in the first-or- der model established in this paper, which indicates the dynamic responses of the rigid flexible cou- pling system with large overall motion accurately. The results also show that the mass has a soften- ing effect on the dynamic behavior of the flexible beam, and the effect would be more obvious when the mass has a larger mass, or lies closer to the tip of the beam.展开更多
Since the first official college English curriculum being drafted out in 1982, English education has been implemented in People's Republic of China for about 30 years. Every curriculum at each stage shades a great li...Since the first official college English curriculum being drafted out in 1982, English education has been implemented in People's Republic of China for about 30 years. Every curriculum at each stage shades a great light on the development of English teaching and learning in different time. Though reviewing the "The College English Teaching Requirement (2007)" (Ministry of Education, 2007), it can be seen that the listening and speaking competences are highly emphasized to cope with the problem of "mute English", and computers are invited to facilitate English learning which make the learning process more individualized. However, there are also some shortcomings should be modified in the future, such as lack of needs analysis and pedagogical support and so on.展开更多
Aiming at the PWM rectifier control strategy of sliding mode control, steady state performance weak Hamiltonian control dynamic tracking performance is poor, the coordinated compound control is proposed, the feedback ...Aiming at the PWM rectifier control strategy of sliding mode control, steady state performance weak Hamiltonian control dynamic tracking performance is poor, the coordinated compound control is proposed, the feedback linearization controller and sliding mode controller Hamiltonian system is obtained, and the design of a coordinated control strategy. In order to verify the accuracy of this method, MATLAB/Simulink is used for simulation analysis. The simulation results show that the composite control can achieve the coordinated dynamic rapid tracking and constant DC output and unit power factor operation, and satisfy the control requirements of the rectifier, effectively reducing the disturbance effect on the system. Compared with Hamiltonian control, the proposed method combines the advantages of the two methods, which have the fast tracking performance and excellent steady-state characteristics, and the research prospect is broad.展开更多
Based on the Lagrange s equation and the finite element method, this paper establishes the dynamic equation of a radar antenna mechanic system which is a high accuracy system and consists of two flexible bodies. Mode ...Based on the Lagrange s equation and the finite element method, this paper establishes the dynamic equation of a radar antenna mechanic system which is a high accuracy system and consists of two flexible bodies. Mode coordinates are used to reduce the orders of equation. Finally, the calculation method and engineering example are given when the rotational velocity of antenna is invariable and the wind velocity is 25?m/s. The error of antenna mechanic system can be estimated using the calculation results.展开更多
The control problem of coordinated motion of a free-floating space rigid manipulator with external disturbance is discussed. By combining linear momentum conversion and the Lagrangian approach, the full-control dynami...The control problem of coordinated motion of a free-floating space rigid manipulator with external disturbance is discussed. By combining linear momentum conversion and the Lagrangian approach, the full-control dynamic equation and the Jacobian relation of a free-floating space rigid manipulator are established and then inverted to the state equation for control design. Based on the terminal sliding mode control (SMC) technique, a mathematical expression of the terminal sliding surface is proposed. The terminal SMC scheme is then developed for coordinated motion between the base's attitude and the end-effector of the free-floating space manipulator with external disturbance. This proposed control scheme not only guarantees the existence of the sliding phase of the closed-loop system, but also ensures that the output tracking error converges to zero in finite time. In addition, because the initial system state is always at the terminal sliding surface, the control scheme can eliminate reaching phase of the SMC and guarantee global robustness and stability of the closed-loop system. A planar free-floating space rigid manipulator is simulated to verify the feasibility of the proposed control scheme.展开更多
A unique metal-organic framework(MOF) [Eu_2(L)_3(phen)_2]_n(1, H_2L = 4,6-dibenzoylisophthalic acid, phen = 1,10-phenanthroline) has been synthesized under hydrothermal conditions and characterized by single-c...A unique metal-organic framework(MOF) [Eu_2(L)_3(phen)_2]_n(1, H_2L = 4,6-dibenzoylisophthalic acid, phen = 1,10-phenanthroline) has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray analysis, elemental analyses, powder X-ray diffraction, TGA measurement as well as IR spectra. The crystal is of triclinic system, space group P1, C_(90)H_(52)Eu_2N_4O_(18), M_r = 1781.32, a = 9.8697(4), b = 16.7466(6), c = 22.2556(10) A, α = 87.113(3), β = 77.575(5), γ = 89.458(3)°, V = 3587.8(3) A^3, Z = 2, D_c = 1.649 g/cm^3, F(000) = 1780, μ(MoKα) = 1.813 mm^(-1), Rint = 0.0181, R = 0.0260 and wR = 0.0592 for 14000 observed reflections with I 〉 2σ(I). X-ray analysis shows that the title compound exhibits a 2D layer structure linked by L ligands with two coordination modes and two distinguished conformations, and further linked into a 3D supramolecular architecture through C-H···O weak interactions between hydrogen of phen phenyl ring and the carboxylate oxygen atom of adjacent sheets. In addition, the luminescence property of 1 was investigated.展开更多
基金National Social Science Foundation Project of China(21FYSB048)Humanities and Social Sciences Research Project of the Ministry of Education(20YJAZH1010).
文摘Under the background of urban renewal, this paper re-explores the tourism development modeof Nanluoguxiang historical and cultural block based on online review data, and puts forward correspondingdevelopment strategies. As a cultural label of a city, historical and cultural blocks should be updated first inorder to achieve sustainable development. By using multi-source big data review and qualitative researchmethods, the perception evaluation of tourists in Nanluoguxiang is obtained, and the shortcomings ofcurrent tourism development mode are analyzed. Furthermore, corresponding improvement strategies andsuggestions are put forward, in order to provide some effective ideas for the sustainable development ofhistorical and cultural blocks in the future.
基金A Study on the Discourse Mode of Administrative Slogans in Anhui Province under the Post-modern Public Discourse Background(A2015025)Master’s degree program in Hefei college(Master of Chinese international education)A Study on the Language Standardization of Public Context and Mass Media-T aking Hefei as an Example(14JD06RW)
文摘Public administration slogans include oral and written slogans which made by governments at all levels according to the policy or administration under the propagation tasks. T he purpose is to enhance propaganda effects by repeating the same concepts and objectives. While the democratic awareness in public discourses is keep growing,there are some surveys on the quality of public administration slogans. In order to improve the quality of public administration slogans,governments in Anhui Province should organize professionals and pay closely attention to the guidance of policy before they sort,edit,produce and release public administration slogans.
基金Supported by the National Natural Science Foundation of China(Nos.20701015,21071059,20788101)
文摘Two 1D coordination polymers Cu2I(C6N3H4)2(1) and CuⅡ(C6N3H4)2·H2O(2) based on benzotriazole(Bta) were hydrothermally synthesized by controlling the crystallization temperature.Single-crystal X-ray diffraction(XRD) analyses reveal that compound 1 is a 1D tubular structure constructed from two types of 1D chains {―Cu―N=N―N―} n,where the Cu(I) ions adopt linear,triangular,and tetrahedral coordination modes to connect two types of Bta ligands via π-π interaction inside the tubular-like chain.For compound 2,the Cu(Ⅱ) ions assume a quadrilateral coordination mode linking to the Bta ligands to give 1D straight chains,which stacks through π-π interactions to construct a 2D layer structure.Further characterizations including elemental analyses,infrared IR spectra,thermogravimetric(TG) analyses and luminescence properties have been done.
文摘Walking is a complex task which includes hundreds of muscles, bones and joints working together to deliver smooth movements. With the complexity, walking has been widely investigated in order to identify the pattern of multi-segment movement and reveal the control mechanism. The degree of freedom and dimensional properties provide a view of the coordinative structure during walking, which has been extensively studied by using dimension reduction technique. In this paper, the studies related to the coordinative structure, dimensions detection and pattern reorganization during walking have been reviewed. Principal component analysis, as a popular technique, is widely used in the processing of human movement data. Both the principle and the outcomes of principal component analysis were introduced in this paper. This technique has been reported to successfully reduce the redundancy within the original data, identify the physical meaning represented by the extracted principal components and discriminate the different patterns. The coordinative structure during walking assessed by this technique could provide further information of the body control mechanism and correlate walking pattern with injury.
基金Supported by Youth Project of Chinese National Social Science Fund(13CGL086)
文摘In China,the vertical coordination development mode of agricultural products can be divided into traditional market-oriented transaction mode with fluctuation according to market conditions,made-to-order on the basis of farmer organization,company leading cooperative mode,share or shareholding cooperative mode,and vertical integration mode. There are differences in coordination characteristics,advantages and disadvantages,and adaptability between different modes. Traditional vertical coordination mode is transforming and upgrading to close and high-efficient mode. In this process,it is influenced by factors such as cost-benefit balance between farmers and agricultural product processing enterprises,special use of agricultural product processing,structure of agricultural product industry chain,and action of local government.
文摘In this paper, we conduct research on the current condition of college tourism personnel training mode and vocational education reforms. Paying attention to the current social development innovation spirit, how to make students possess the necessary ability to innovate, is this the prime problem of the education. A lot of highly educated personnel in order to better adapt to social development and changes, constantly to learn knowledge, also has the characteristics of vocational college students. Our research combines the characteristics of the college tourism personnel training mode with the education reform which will enhance the performance of the teaching process.
基金Project supported by the Natural Science Foundation of Shandong Province,China(Grant No.ZR2014AM026)the Taishan Scholar Project of Shandong Province,China
文摘One-photon absorption and two-photon absorption(TPA) properties of three tris(picolyl)amine-based zinc ion sensors are investigated by employing the density functional response theory in combination with the polarizable continuum model.The different isomer and coordination geometry of each probe are taken into account. Special emphasis is placed on the effects of isomerism and the coordination mode on the optical properties. The intra-molecular charge transfer(ICT)properties are specified by natural bond orbital charge analysis. It is shown that the isomerism has non-negligible effects on TPA properties of free ligands. It is found that both the TPA wavelength and the cross section are highly dependent on the coordination mode. When the zinc ion connects with the picolyl unit in the middle of a ligand, the zinc complex has a large TPA intensity in a long wavelength range due to the increased ICT mechanism.
基金the Natural Science Foundation of Shandong Province,China(Grant No.ZR2014AM026).
文摘The properties of one-photon absorption(OPA),emission and two-photon absorption(TPA)of a bipyridine-based zinc ion probe are investigated employing the density functional theory in combination with response functions.The responsive mechanism and coordination mode effect are explored.The structural fluctuation is illustrated by molecular dynamics simulation.The calculated OPA and emission wavelengths of the probe are consistent with the experimental data.It is found that the red-shift of OPA wavelength and the enhancement of TPA intensity are induced by the increased intra-molecular charge transfer mechanism upon metal binding.The structural fluctuation could result in the blue-shift of TPA wavelength and the decrease of the TPA cross section.The TPA properties are quite different among the zinc complexes with different coordination modes.The TPA wavelength of the complexes with two ligands is close to that of the probe,which is in agreement with the experimental observation.
文摘In this paper, we conduct research on the professional development mode of primary and the secondary school English teachers. Teacher training is an effective way to promote the teachers’ professional development that is an important content of teacher education, and teachers’ pre-service training, entry education together constitute a complete content of teacher education, teacher training, of course and is also the need of teachers’ lifelong learning, for the national government attached great importance to teachers’ training work. English teaching is a kind of creative and complicated work, and whole teaching activity involves teachers, students, teaching objective and the teaching content, teaching means and teaching links such as basic elements. This paper proposes the novel perspective of the professional development mode for teachers that will be meaningful.
文摘In order to better carry out research on education and teaching,the author consulted relevant literature on blended teaching mode from 2011-2021 through CNKI,Web of Science and other websites,summarized and analyzed the research status of blended teaching mode,in order to lay a good foundation for studying blended teaching mode in course teaching.
文摘A rigid flexible coupling physical model which can represent a flexible spacecraft is investigated in this paper. By applying the mechanics theory in a non-inertial coordinate system,the rigid flexible coupling dynamic model with dynamic stiffening is established via the subsystemmodeling framework. It is clearly elucidated for the first time that,dynamic stiffening is produced by the coupling effect of the centrifugal inertial load distributed on the beamand the transverse vibration deformation of the beam. The modeling approach in this paper successfully avoids problems which are caused by other popular modeling methods nowadays: the derivation process is too complex by using only one dynamic principle; a clearly theoretical explanation for dynamic stiffening can't be provided. First,the continuous dynamic models of the flexible beamand the central rigid body are established via structural dynamics and angular momentumtheory respectively. Then,based on the conclusions of orthogonalization about the normal constrained modes,the finite dimensional dynamic model suitable for controller design is obtained. The numerical simulation validations showthat: dynamic stiffening is successfully incorporated into the dynamic characteristics of the first-order model established in this paper,which can indicate the dynamic responses of the rigid flexible coupling system with large overall motion accurately,and has a clear modeling mechanism,concise expressions and a good convergence.
基金supported by the Natural Science Foundation of Henan Province(172102210410 and 172102310476)
文摘A novel nitro-coordinated potassium compound [K(Htdc)(H_2O)]_n(tdc = 3-nitro-thiophene-2,5-dicarboxylate), has been synthesized and characterized. The complex with a two-dimensional(2D) layer structure contains an infinite K-O ladder-shaped chain, which is connected through carboxyl and unusual nitro-coordination of Htdc– anion. Then the 2D layers are further extended by intermolecular hydrogen-bonding to form a three-dimensional(3D) supramoleculalr network. Variable temperature powder X-ray diffractions, thermogravimetric analysis and nuclear magnetic resonance studies exhibit that the compound has a thermal-induced decarboxylative behavior.
文摘A new intelligent control method for welding positioner is proposed. Applying an improved fuzzy controller and a variable PID controller, a two-mode intelligent coordinating controller ( TMICC ) is designed on basis of fuzzy logic and rules. The simulation and experimental results show that this control system can obtain better dynamic and static characteristics.
文摘The rigid flexible coupling system with a mass at non-tip position of the flexible beam is studied in this paper. Using the theory about mechanics problems in a non-inertial coordinate sys- tem, the dynamic equations of the rigid flexible coupling system with dynamic stiffening are estab- lished. It is clearly elucidated for the first time that, dynamic stiffening is produced by the coupling effect of the centrifugal inertial load distributed on the beam and the transverse vibration deformation of the beam. The modeling approach in this paper successfully solves problems of popular modeling methods nowadays: the derivation process is too complex by using only one dynamic principle; a clearly theoretical mechanism for dynamic stiffening can' t be offered. First, the mass at non-tip po- sition is incorporated into the continuous dynamic equations of the system by use of the Dirac lunch tion and the Heaviside function. Then, based on the conclusions of orthogonalization about the nor- mal constrained modes, the finite dimensional state space equations suitable for controller design are obtained. The numerical simulation results show that: dynamic stiffening is included in the first-or- der model established in this paper, which indicates the dynamic responses of the rigid flexible cou- pling system with large overall motion accurately. The results also show that the mass has a soften- ing effect on the dynamic behavior of the flexible beam, and the effect would be more obvious when the mass has a larger mass, or lies closer to the tip of the beam.
文摘Since the first official college English curriculum being drafted out in 1982, English education has been implemented in People's Republic of China for about 30 years. Every curriculum at each stage shades a great light on the development of English teaching and learning in different time. Though reviewing the "The College English Teaching Requirement (2007)" (Ministry of Education, 2007), it can be seen that the listening and speaking competences are highly emphasized to cope with the problem of "mute English", and computers are invited to facilitate English learning which make the learning process more individualized. However, there are also some shortcomings should be modified in the future, such as lack of needs analysis and pedagogical support and so on.
文摘Aiming at the PWM rectifier control strategy of sliding mode control, steady state performance weak Hamiltonian control dynamic tracking performance is poor, the coordinated compound control is proposed, the feedback linearization controller and sliding mode controller Hamiltonian system is obtained, and the design of a coordinated control strategy. In order to verify the accuracy of this method, MATLAB/Simulink is used for simulation analysis. The simulation results show that the composite control can achieve the coordinated dynamic rapid tracking and constant DC output and unit power factor operation, and satisfy the control requirements of the rectifier, effectively reducing the disturbance effect on the system. Compared with Hamiltonian control, the proposed method combines the advantages of the two methods, which have the fast tracking performance and excellent steady-state characteristics, and the research prospect is broad.
文摘Based on the Lagrange s equation and the finite element method, this paper establishes the dynamic equation of a radar antenna mechanic system which is a high accuracy system and consists of two flexible bodies. Mode coordinates are used to reduce the orders of equation. Finally, the calculation method and engineering example are given when the rotational velocity of antenna is invariable and the wind velocity is 25?m/s. The error of antenna mechanic system can be estimated using the calculation results.
基金the National Natural Science Foundation of China(Nos.10672040 and 10372022)the Natural Science Foundation of Fujian Province,China(No.E0410008)
文摘The control problem of coordinated motion of a free-floating space rigid manipulator with external disturbance is discussed. By combining linear momentum conversion and the Lagrangian approach, the full-control dynamic equation and the Jacobian relation of a free-floating space rigid manipulator are established and then inverted to the state equation for control design. Based on the terminal sliding mode control (SMC) technique, a mathematical expression of the terminal sliding surface is proposed. The terminal SMC scheme is then developed for coordinated motion between the base's attitude and the end-effector of the free-floating space manipulator with external disturbance. This proposed control scheme not only guarantees the existence of the sliding phase of the closed-loop system, but also ensures that the output tracking error converges to zero in finite time. In addition, because the initial system state is always at the terminal sliding surface, the control scheme can eliminate reaching phase of the SMC and guarantee global robustness and stability of the closed-loop system. A planar free-floating space rigid manipulator is simulated to verify the feasibility of the proposed control scheme.
基金supported by the NNSFC(No.21301170)Xiaonei Foundation of Changchun University of Technology
文摘A unique metal-organic framework(MOF) [Eu_2(L)_3(phen)_2]_n(1, H_2L = 4,6-dibenzoylisophthalic acid, phen = 1,10-phenanthroline) has been synthesized under hydrothermal conditions and characterized by single-crystal X-ray analysis, elemental analyses, powder X-ray diffraction, TGA measurement as well as IR spectra. The crystal is of triclinic system, space group P1, C_(90)H_(52)Eu_2N_4O_(18), M_r = 1781.32, a = 9.8697(4), b = 16.7466(6), c = 22.2556(10) A, α = 87.113(3), β = 77.575(5), γ = 89.458(3)°, V = 3587.8(3) A^3, Z = 2, D_c = 1.649 g/cm^3, F(000) = 1780, μ(MoKα) = 1.813 mm^(-1), Rint = 0.0181, R = 0.0260 and wR = 0.0592 for 14000 observed reflections with I 〉 2σ(I). X-ray analysis shows that the title compound exhibits a 2D layer structure linked by L ligands with two coordination modes and two distinguished conformations, and further linked into a 3D supramolecular architecture through C-H···O weak interactions between hydrogen of phen phenyl ring and the carboxylate oxygen atom of adjacent sheets. In addition, the luminescence property of 1 was investigated.