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
[Objective] The aim was to study the development and application of operation in comprehensive platform of professional meteorological station.[Method] Taking the operation platform of professional meteorological stat...[Objective] The aim was to study the development and application of operation in comprehensive platform of professional meteorological station.[Method] Taking the operation platform of professional meteorological station in Yantai City as an example,and by dint of VB language and Mysql database technology,the ideas of comprehensive platform development of operation in professional meteorological station,main contents of the platform and its main functions were introduced.[Result] The platform mainly used VB language and Mysql database technology.Gathering together the forecast making,forecast inventory and check,surveillance of data uploading and machine operation and records of shifts,the interface was simple,visual and easy to handle.It reduced reporters’ workload,improved their work efficiency and was the favorite of majority reporters.[Conclusion] The study provided reference for the improvement of work efficiency of each professional meteorological station.展开更多
The rapid development of the“Internet+”has ushered in a new era of global digital technology innovation.Concurrent with the deepening trends of economic globalization and integration,international trade is progressi...The rapid development of the“Internet+”has ushered in a new era of global digital technology innovation.Concurrent with the deepening trends of economic globalization and integration,international trade is progressively undergoing extensive digitization,with cross-border e-commerce emerging as a significant manifestation of this transformation.Within this landscape,the cross-border e-commerce B2B platform is anticipated to become a pivotal driver for China’s cross-border trade growth,representing a strategic opportunity for trade transformation.This paper provides a comprehensive examination of the concepts,characteristics,and development status of cross-border e-commerce and B2B platforms,considering both global and Chinese perspectives.Focusing on a prominent case study,Alibaba International Station,a B2B cross-border e-commerce platform,the paper delves into its business model and core competencies,offering a thorough analysis of its role in the intricacies of international e-commerce and its contribution to the field.Drawing on insights gained,the paper concludes by presenting targeted recommendations from both the platform and government perspectives.These suggestions are informed by a nuanced understanding of the development opportunities and challenges facing China’s cross-border e-commerce B2B platforms.展开更多
为了满足新形势下航天地面站快速交付、灵活部署与升级的需求,分析了基于模型的系统工程(Model-based Systems Engineering,MBSE)的航天地面系统模型,设计了一种适用于航天地面系统的低代码开发平台。该平台基于MBSE模型并通过可视化接...为了满足新形势下航天地面站快速交付、灵活部署与升级的需求,分析了基于模型的系统工程(Model-based Systems Engineering,MBSE)的航天地面系统模型,设计了一种适用于航天地面系统的低代码开发平台。该平台基于MBSE模型并通过可视化接口来构建包含软件功能、运行流程、数据处理等内容的应用程序。应用低代码软件平台,降低了软件开发的复杂性,满足装备快速升级的需求,研制时间较传统方法缩短了近45%。展开更多
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[Objective] The aim was to study the development and application of operation in comprehensive platform of professional meteorological station.[Method] Taking the operation platform of professional meteorological station in Yantai City as an example,and by dint of VB language and Mysql database technology,the ideas of comprehensive platform development of operation in professional meteorological station,main contents of the platform and its main functions were introduced.[Result] The platform mainly used VB language and Mysql database technology.Gathering together the forecast making,forecast inventory and check,surveillance of data uploading and machine operation and records of shifts,the interface was simple,visual and easy to handle.It reduced reporters’ workload,improved their work efficiency and was the favorite of majority reporters.[Conclusion] The study provided reference for the improvement of work efficiency of each professional meteorological station.
文摘The rapid development of the“Internet+”has ushered in a new era of global digital technology innovation.Concurrent with the deepening trends of economic globalization and integration,international trade is progressively undergoing extensive digitization,with cross-border e-commerce emerging as a significant manifestation of this transformation.Within this landscape,the cross-border e-commerce B2B platform is anticipated to become a pivotal driver for China’s cross-border trade growth,representing a strategic opportunity for trade transformation.This paper provides a comprehensive examination of the concepts,characteristics,and development status of cross-border e-commerce and B2B platforms,considering both global and Chinese perspectives.Focusing on a prominent case study,Alibaba International Station,a B2B cross-border e-commerce platform,the paper delves into its business model and core competencies,offering a thorough analysis of its role in the intricacies of international e-commerce and its contribution to the field.Drawing on insights gained,the paper concludes by presenting targeted recommendations from both the platform and government perspectives.These suggestions are informed by a nuanced understanding of the development opportunities and challenges facing China’s cross-border e-commerce B2B platforms.
文摘为了满足新形势下航天地面站快速交付、灵活部署与升级的需求,分析了基于模型的系统工程(Model-based Systems Engineering,MBSE)的航天地面系统模型,设计了一种适用于航天地面系统的低代码开发平台。该平台基于MBSE模型并通过可视化接口来构建包含软件功能、运行流程、数据处理等内容的应用程序。应用低代码软件平台,降低了软件开发的复杂性,满足装备快速升级的需求,研制时间较传统方法缩短了近45%。
