Forward osmosis(FO), as an emerging technology, is influenced by different factors such as operating conditions,module characteristics, and membrane properties. The general aim of this study was to develop a suitable(...Forward osmosis(FO), as an emerging technology, is influenced by different factors such as operating conditions,module characteristics, and membrane properties. The general aim of this study was to develop a suitable(flexible,comprehensive, and convenient to use) computational tool which is able to simulate osmosis through an asymmetric membrane oriented in pressure retarded osmosis(PRO) mode in a wide variety of scenarios. For this purpose, an agent-based model was created in NetLogo platform, which is an easy-to-use application environment with graphical visualization abilities and well suited for modeling a complex system evolving over time. The simulation results were validated with empirical data obtained from literature and a great agreement was observed. The effect of various parameters on process performance was investigated in terms of temperature,cross-flow velocity, length of the module, pure water permeability coefficient, and structural parameter of the membrane. Results demonstrated that the increase in all parameters, except structural parameter of the membrane and the length of module led to the increase of average water flux. Moreover, nine different draw solutes were selected in order to assess the influence of net bulk osmotic pressure difference between the draw solution(DS) and feed solution(FS)(known as the driving force of FO process) on water flux. Based on the findings of this paper, the performance of FO process(PRO mode) can be efficiently evaluated using the NetL ogo platform.展开更多
An optimal active sliding mode controller with specified decay rate design is proposed to control the wave-induced offshore jacket-type platform with active mass damper （AMD）. Irregular wave loading is approximated ...An optimal active sliding mode controller with specified decay rate design is proposed to control the wave-induced offshore jacket-type platform with active mass damper （AMD）. Irregular wave loading is approximated by finite sums of Fourier series, and its dynamic characteristics are governed by an exosystem derived from the linearized Morison equation. The offshore platform system is first decomposed into two virtual subsystems based on a linear transformation. By considering the velocity of AMD as a virtual control force for the first subsystem, the optimal virtual controller is derived. Furthermore, an optimal sliding mode surface with specified decay rate is proposed. Then, the active sliding mode controller is designed to ensure that the state trajectories reach the sliding surface in finite time and remain on it thereafter. Numerical simulation is employed to verify the effectiveness of the proposed approach.展开更多
The stratosphere airship provides a unique and promising platform for earth observation. Researches on the project design and control scheme for earth observation platforms are still rarely documented. Nonlinear dynam...The stratosphere airship provides a unique and promising platform for earth observation. Researches on the project design and control scheme for earth observation platforms are still rarely documented. Nonlinear dynamics, model uncertainties, and external disturbances contribute to the difficulty in maneuvering the stratosphere airship. A key technical challenge for the earth observation platform is station keeping, or the ability to remain fixed over a geo-location. This paper investigates the conceptual design, modeling and station-keeping attitude control of the near-space earth observation platform. A conceptual design of the earth observation platform is presented. The dynamics model of the platform is derived from the Newton-Euler formulation, and the station-keeping control system of the platform is formulated. The station-keeping attitude control approach for the platform is proposed. The multi-input multi-output nonlinear control system is decoupled into three single-input single-output linear subsystems via feedback linearization, the attitude controller design is carried out on the new linear systems using terminal sliding mode control, and the global stability of the closed-loop system is proven by using the Lyapunov theorem. The performance of the designed control system is simulated by using the variable step Runge-Kutta integrator. Simulation results show that the control system tracks the commanded attitude with an error of zero, which verify the effectiveness and robustness of the designed control system in the presence of parametric uncertainties. The near-space earth observation platform has several advantages over satellites, such as high resolution, fast to deploy, and convenient to retrieve, and the proposed control scheme provides an effective approach for station-keeping attitude control of the earth observation platform.展开更多
In this study, the five-in-one community mass prevention and mass treatment group established in Wuhan to curb novel coronavirus outbreak in 2019 to 2020 is introduced. Various public health propaganda methods are use...In this study, the five-in-one community mass prevention and mass treatment group established in Wuhan to curb novel coronavirus outbreak in 2019 to 2020 is introduced. Various public health propaganda methods are used, including community loudspeakers and community bulletin boards. In the meantime, WeChat platform account named “Wuhan neighborhood on WeChat” is registered and opened, and a Group Chat on WeChat is created for grid management. A diversity of on-line and off-line countermeasures against the novel coronavirus outbreak are implemented via the WeChat platform: three-early measures (early discovery, early reporting, and early treatment), centralized management, community-based reporting, hierarchical diagnosis, and treatment system, isolation of mild patients at designated facilities, diagnosis and treatment appointment system for patients with fever, patient transferral in special vehicles, terminal disinfection at homes, psychological support and daily caring plan for special populations. This WeChat platform allows for an all-region, all-around, all-time and entire population-coverage control of novel coronavirus outbreak, with the extension and strengthening of health propaganda, guidance for seeking medical assistance, mass prevention and mass treatment, and health self-management among the community residents. Great effect has been achieved in novel coronavirus control so far. The five-in-one community management mode of Wuhan plus “Wuhan neighborhood on WeChat” plays an important role in relieving the shortage of health service resources and resolving the problem of limited service scope of professional medical staff in Wuhan, and ultimately contributes to the overall novel coronavirus control.展开更多
As a platform bridging classroom teaching and online teaching for higher vocational college(HVC)English,WeChat expands the dimension of HVC English teaching.This paper first introduces basic functions and characterist...As a platform bridging classroom teaching and online teaching for higher vocational college(HVC)English,WeChat expands the dimension of HVC English teaching.This paper first introduces basic functions and characteristics of WeChat,then analyzes problems existing in current HVC English teaching and finally puts forward specific ways to design HVC English blended learning mode based on WeChat platform in four steps:warming-up,text analysis,exercises and post-course expansion.展开更多
This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, using MATLAB. The tendon is...This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation(lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.展开更多
[目的]探讨“人工智能+”背景下中医药信息学人才培养方案的优化路径。[方法]结合当前人工智能技术驱动下教育教学改革趋势,采用案例分析和比较研究的方法,分析浙江中医药大学中医药信息学专业课程结构、教学内容、实践教学平台建设等...[目的]探讨“人工智能+”背景下中医药信息学人才培养方案的优化路径。[方法]结合当前人工智能技术驱动下教育教学改革趋势,采用案例分析和比较研究的方法,分析浙江中医药大学中医药信息学专业课程结构、教学内容、实践教学平台建设等方面存在的问题,并针对性地提出优化策略。[结果]浙江中医药大学中医药信息学人才培养存在以下问题:一是课程结构失衡,人工智能相关课程偏少;二是教学内容更新滞后,理论教学占比较大,实践环节不足;三是人工智能实践平台与机会缺乏。针对课程结构失衡,优化策略包括强化顶层设计,增设特色化“中医药+人工智能”课程;针对实践环节不足,应建立基于学习成果导向(outcome based education,OBE)的教学模式;针对实践平台缺乏,建议学校、医院、企业三方联合建设实践平台,加强跨学科复合人才培养。策略实施后,学生的课堂参与度、创新能力提升明显,在各类竞赛中表现突出,教学科研成果丰硕,毕业生就业率和升学率较优化前均有明显提高。[结论]通过构建“中医药+人工智能”特色课程体系、校院企协同实践平台以及跨学科教学团队,优化人才培养策略,形成可推广的“中医药+人工智能”复合型人才培养模式,为“人工智能+”背景下中医药信息学教育改革提供了理论支撑和实践路径,助力国家数字中医药战略发展。展开更多
Active vibration control is needed for future space telescopes, space laser communication and other precision sensitive payloads which require ultra-quiet environments. A Stewart platform based hybrid isolator with 6 ...Active vibration control is needed for future space telescopes, space laser communication and other precision sensitive payloads which require ultra-quiet environments. A Stewart platform based hybrid isolator with 6 hybrid struts is the effective system for active/passive vibration isolation over 5-250 Hz band. Using an identification transfer matrix of the Stewart platform, the coupling analysis of six channels is provided. A dynamics model is derived, and the rigid mode is removed to keep the signal of pointing control. Multi objective robust H∞ and μ synthesis strategies, based on singular values and structured singular values respectively, are presented, which simultaneously satisfy the low frequency pointing and high frequency disturbance rejection requirements and take account of the model uncertainty, parametric uncertainty and sensor noise. Then, by performing robust stability test, it is shown that the two controllers are robust to the uncertainties, the robust stability margin of H, controller is less than that of μ controller, but the order of μ controller is higher than that of H, controller, so the balanced controller reduction is provided. Additionally, the μ controller is compared with a PI controller. The time domain simulation of the μ controller indicates that the two robust control strategies are effective for keeping the pointing command and isolating the harmonic and stochastic disturbances.展开更多
文摘Forward osmosis(FO), as an emerging technology, is influenced by different factors such as operating conditions,module characteristics, and membrane properties. The general aim of this study was to develop a suitable(flexible,comprehensive, and convenient to use) computational tool which is able to simulate osmosis through an asymmetric membrane oriented in pressure retarded osmosis(PRO) mode in a wide variety of scenarios. For this purpose, an agent-based model was created in NetLogo platform, which is an easy-to-use application environment with graphical visualization abilities and well suited for modeling a complex system evolving over time. The simulation results were validated with empirical data obtained from literature and a great agreement was observed. The effect of various parameters on process performance was investigated in terms of temperature,cross-flow velocity, length of the module, pure water permeability coefficient, and structural parameter of the membrane. Results demonstrated that the increase in all parameters, except structural parameter of the membrane and the length of module led to the increase of average water flux. Moreover, nine different draw solutes were selected in order to assess the influence of net bulk osmotic pressure difference between the draw solution(DS) and feed solution(FS)(known as the driving force of FO process) on water flux. Based on the findings of this paper, the performance of FO process(PRO mode) can be efficiently evaluated using the NetL ogo platform.
基金supported in part by the National Natural Science Foundation of China (Grant Nos.40776051,60874029 and 40806040)the Natural Science Foundation of Zhejiang Province (Grant No.Y107232)the Scientific Research Fund of Zhejiang Provincial Education Department (Grant No.Y200702660)
文摘An optimal active sliding mode controller with specified decay rate design is proposed to control the wave-induced offshore jacket-type platform with active mass damper （AMD）. Irregular wave loading is approximated by finite sums of Fourier series, and its dynamic characteristics are governed by an exosystem derived from the linearized Morison equation. The offshore platform system is first decomposed into two virtual subsystems based on a linear transformation. By considering the velocity of AMD as a virtual control force for the first subsystem, the optimal virtual controller is derived. Furthermore, an optimal sliding mode surface with specified decay rate is proposed. Then, the active sliding mode controller is designed to ensure that the state trajectories reach the sliding surface in finite time and remain on it thereafter. Numerical simulation is employed to verify the effectiveness of the proposed approach.
基金supported by Hunan Provincial Innovation Foundation for Postgraduate(Grant No. CX2011B005)National University of Defense Technology Innovation Foundation for Postgraduate, China(GranNo. B110105)
文摘The stratosphere airship provides a unique and promising platform for earth observation. Researches on the project design and control scheme for earth observation platforms are still rarely documented. Nonlinear dynamics, model uncertainties, and external disturbances contribute to the difficulty in maneuvering the stratosphere airship. A key technical challenge for the earth observation platform is station keeping, or the ability to remain fixed over a geo-location. This paper investigates the conceptual design, modeling and station-keeping attitude control of the near-space earth observation platform. A conceptual design of the earth observation platform is presented. The dynamics model of the platform is derived from the Newton-Euler formulation, and the station-keeping control system of the platform is formulated. The station-keeping attitude control approach for the platform is proposed. The multi-input multi-output nonlinear control system is decoupled into three single-input single-output linear subsystems via feedback linearization, the attitude controller design is carried out on the new linear systems using terminal sliding mode control, and the global stability of the closed-loop system is proven by using the Lyapunov theorem. The performance of the designed control system is simulated by using the variable step Runge-Kutta integrator. Simulation results show that the control system tracks the commanded attitude with an error of zero, which verify the effectiveness and robustness of the designed control system in the presence of parametric uncertainties. The near-space earth observation platform has several advantages over satellites, such as high resolution, fast to deploy, and convenient to retrieve, and the proposed control scheme provides an effective approach for station-keeping attitude control of the earth observation platform.
文摘In this study, the five-in-one community mass prevention and mass treatment group established in Wuhan to curb novel coronavirus outbreak in 2019 to 2020 is introduced. Various public health propaganda methods are used, including community loudspeakers and community bulletin boards. In the meantime, WeChat platform account named “Wuhan neighborhood on WeChat” is registered and opened, and a Group Chat on WeChat is created for grid management. A diversity of on-line and off-line countermeasures against the novel coronavirus outbreak are implemented via the WeChat platform: three-early measures (early discovery, early reporting, and early treatment), centralized management, community-based reporting, hierarchical diagnosis, and treatment system, isolation of mild patients at designated facilities, diagnosis and treatment appointment system for patients with fever, patient transferral in special vehicles, terminal disinfection at homes, psychological support and daily caring plan for special populations. This WeChat platform allows for an all-region, all-around, all-time and entire population-coverage control of novel coronavirus outbreak, with the extension and strengthening of health propaganda, guidance for seeking medical assistance, mass prevention and mass treatment, and health self-management among the community residents. Great effect has been achieved in novel coronavirus control so far. The five-in-one community management mode of Wuhan plus “Wuhan neighborhood on WeChat” plays an important role in relieving the shortage of health service resources and resolving the problem of limited service scope of professional medical staff in Wuhan, and ultimately contributes to the overall novel coronavirus control.
文摘As a platform bridging classroom teaching and online teaching for higher vocational college(HVC)English,WeChat expands the dimension of HVC English teaching.This paper first introduces basic functions and characteristics of WeChat,then analyzes problems existing in current HVC English teaching and finally puts forward specific ways to design HVC English blended learning mode based on WeChat platform in four steps:warming-up,text analysis,exercises and post-course expansion.
文摘This paper studies the application of mathematical models to analyze the vortex-induced vibrations of the tendons of a given TLP along the Indian coastline, by using an analytical approach, using MATLAB. The tendon is subjected to a steady current load, which causes vortex-shedding downstream, leading to cross-flow vibrations. The magnitude of the excitation(lift and drag coefficients) depends on the vortex-shedding frequency. The resulting vibration is studied for possible resonant behavior. The excitation force is quantified empirically, the added mass by potential flow hydrodynamics, and the vibration by normal mode summation method. Non-linear viscous damping of the water is considered. The non-linear oscillations are studied by the phase-plane method, investigating the limit-cycle oscillations. The stable/unstable regions of the dynamic behavior are demarcated. The modal contribution to the total deflection is studied to establish the possibility of resonance of one of the wet modes with the vortex-shedding frequency.
文摘[目的]探讨“人工智能+”背景下中医药信息学人才培养方案的优化路径。[方法]结合当前人工智能技术驱动下教育教学改革趋势,采用案例分析和比较研究的方法,分析浙江中医药大学中医药信息学专业课程结构、教学内容、实践教学平台建设等方面存在的问题,并针对性地提出优化策略。[结果]浙江中医药大学中医药信息学人才培养存在以下问题:一是课程结构失衡,人工智能相关课程偏少;二是教学内容更新滞后,理论教学占比较大,实践环节不足;三是人工智能实践平台与机会缺乏。针对课程结构失衡,优化策略包括强化顶层设计,增设特色化“中医药+人工智能”课程;针对实践环节不足,应建立基于学习成果导向(outcome based education,OBE)的教学模式;针对实践平台缺乏,建议学校、医院、企业三方联合建设实践平台,加强跨学科复合人才培养。策略实施后,学生的课堂参与度、创新能力提升明显,在各类竞赛中表现突出,教学科研成果丰硕,毕业生就业率和升学率较优化前均有明显提高。[结论]通过构建“中医药+人工智能”特色课程体系、校院企协同实践平台以及跨学科教学团队,优化人才培养策略,形成可推广的“中医药+人工智能”复合型人才培养模式,为“人工智能+”背景下中医药信息学教育改革提供了理论支撑和实践路径,助力国家数字中医药战略发展。
文摘Active vibration control is needed for future space telescopes, space laser communication and other precision sensitive payloads which require ultra-quiet environments. A Stewart platform based hybrid isolator with 6 hybrid struts is the effective system for active/passive vibration isolation over 5-250 Hz band. Using an identification transfer matrix of the Stewart platform, the coupling analysis of six channels is provided. A dynamics model is derived, and the rigid mode is removed to keep the signal of pointing control. Multi objective robust H∞ and μ synthesis strategies, based on singular values and structured singular values respectively, are presented, which simultaneously satisfy the low frequency pointing and high frequency disturbance rejection requirements and take account of the model uncertainty, parametric uncertainty and sensor noise. Then, by performing robust stability test, it is shown that the two controllers are robust to the uncertainties, the robust stability margin of H, controller is less than that of μ controller, but the order of μ controller is higher than that of H, controller, so the balanced controller reduction is provided. Additionally, the μ controller is compared with a PI controller. The time domain simulation of the μ controller indicates that the two robust control strategies are effective for keeping the pointing command and isolating the harmonic and stochastic disturbances.
