Conceptual design, data model and key techniques of "Geo-engineer 3D assistant", an underground 3D GIS oriented to geology and mine application, were discussed. In particular, the importance of high-order sm...Conceptual design, data model and key techniques of "Geo-engineer 3D assistant", an underground 3D GIS oriented to geology and mine application, were discussed. In particular, the importance of high-order smoothing triangular pieces to surface's fine expression in geological modeling was emphasized. The contour mode is the most favorite mode of the three modes about surface expression: DEM, TIN and contour. Topology in underground 3D modeling with CAGD was compared. From the view of boundary and coboundary, which is soul of IS 19107 (Geographic information spatial schema), 3D underground topology was re-examined.展开更多
This article introduces the basic situation of Yanziqian Tobacco Farmers' Mutual Assistance and Cooperation Association in Jiamachi Town of Xianfeng County.It analyzes the operating mode of tobacco farmers' mu...This article introduces the basic situation of Yanziqian Tobacco Farmers' Mutual Assistance and Cooperation Association in Jiamachi Town of Xianfeng County.It analyzes the operating mode of tobacco farmers' mutual assistance and cooperation association,and conducts a comparative analysis of tobacco farmers' costs and benefits before and after participating in mutual assistance and cooperation.Studies show that the mode of tobacco farmers' mutual assistance and cooperation,is conducive to reducing labor in curing link,promoting the quality of tobacco,increasing tobacco farmers' income,which is worthy of promotion.展开更多
"College English Curriculum Requirements", edited by Department of Higher Education(2007), put forward clearly one of the key points of the national College English teaching reform was to strengthen the appl..."College English Curriculum Requirements", edited by Department of Higher Education(2007), put forward clearly one of the key points of the national College English teaching reform was to strengthen the application of computer to college English teaching and apply computer-and-classroom-based English teaching mode, improving the previous mode dominated by a single teacher. Most colleges and universities in China have basically achieved the popularity of computer multimedia classrooms and campus networks. However, according to researches(Xia, 2002), most teachers still hold the main role of them in classes as"language interpreter"and"language instructor". Although advanced computer technology has been provided, most teachers feel confused or difficult in using it to assist their English teaching efficiently. As a consequence, computer technology fail to play its role in English classes. Driven by the great development of science and technology, computer has brought about incredible changes in every aspect of social life since 1980 s. In current times, almost every aspect of college students' life has been closely associated with computer. However, in most situations, computer is not taken as a typical language learning tool in their daily life. It is known that most students' English basis is relatively weak in vocational colleges; meanwhile, the way in which they learned English during the middle school period was basically translation- based teaching. Thus they have little or even no interest in English learning at all. In this way, discovering a new and interesting way with the aid of computer to learn English is of essential importance. Based on this, the paper discusses five major aspects under the circumstance of computer-assisted English learning. It is hoped that vocational college English teaching and learning can become more efficient by means of computer technology, finally students' English learning motivation and English competence can be enhanced to a great extent.展开更多
为了提高伺服电机系统的动态响应速度、抗干扰能力,解决输入饱和的问题,课题组基于扩张状态观测器(extended state observer,ESO)和抗饱和输入(anti-saturation input,ASI)辅助系统设计了伺服电机的运动控制方案。首先,建立了伺服电机...为了提高伺服电机系统的动态响应速度、抗干扰能力,解决输入饱和的问题,课题组基于扩张状态观测器(extended state observer,ESO)和抗饱和输入(anti-saturation input,ASI)辅助系统设计了伺服电机的运动控制方案。首先,建立了伺服电机的数学模型,将系统阻尼和系统不确定性归为扰动,将扰动设为系统的扩张状态;然后在等效反步滑模控制(backstepping sliding mode control,BSMC)的基础上,引入了ASI辅助系统和ESO,解决输入饱和问题,并抑制内、外干扰;采用双曲正切饱和函数替换符号函数以减小滑模控制的抖振;通过李雅普诺夫稳定性方法检验所提出控制器的稳定性。最后,将基于ESO和ASI的等效反步滑模控制与比例积分微分(proportional integral differential,PID)控制、滑模控制(sliding mode control,SMC)进行仿真对比。结果表明:相较于传统PID和SMC控制器,课题组所设计的控制器可以实现伺服电机的无超调快速响应,解决了输入饱和问题,并具有较好的抗干扰能力和减小输入冲击的作用。展开更多
基金Project(A11024)supported by the Key Laboratory Fund of Geo-Informatics of State Bureau of Surveying and MappingProject(7771022)supported by the Basic Research Fund for Chinese Academy of Surveying and MappingProject(2010AA22202)supported by the National High-tech Research and Development Program of China
文摘Conceptual design, data model and key techniques of "Geo-engineer 3D assistant", an underground 3D GIS oriented to geology and mine application, were discussed. In particular, the importance of high-order smoothing triangular pieces to surface's fine expression in geological modeling was emphasized. The contour mode is the most favorite mode of the three modes about surface expression: DEM, TIN and contour. Topology in underground 3D modeling with CAGD was compared. From the view of boundary and coboundary, which is soul of IS 19107 (Geographic information spatial schema), 3D underground topology was re-examined.
文摘This article introduces the basic situation of Yanziqian Tobacco Farmers' Mutual Assistance and Cooperation Association in Jiamachi Town of Xianfeng County.It analyzes the operating mode of tobacco farmers' mutual assistance and cooperation association,and conducts a comparative analysis of tobacco farmers' costs and benefits before and after participating in mutual assistance and cooperation.Studies show that the mode of tobacco farmers' mutual assistance and cooperation,is conducive to reducing labor in curing link,promoting the quality of tobacco,increasing tobacco farmers' income,which is worthy of promotion.
文摘"College English Curriculum Requirements", edited by Department of Higher Education(2007), put forward clearly one of the key points of the national College English teaching reform was to strengthen the application of computer to college English teaching and apply computer-and-classroom-based English teaching mode, improving the previous mode dominated by a single teacher. Most colleges and universities in China have basically achieved the popularity of computer multimedia classrooms and campus networks. However, according to researches(Xia, 2002), most teachers still hold the main role of them in classes as"language interpreter"and"language instructor". Although advanced computer technology has been provided, most teachers feel confused or difficult in using it to assist their English teaching efficiently. As a consequence, computer technology fail to play its role in English classes. Driven by the great development of science and technology, computer has brought about incredible changes in every aspect of social life since 1980 s. In current times, almost every aspect of college students' life has been closely associated with computer. However, in most situations, computer is not taken as a typical language learning tool in their daily life. It is known that most students' English basis is relatively weak in vocational colleges; meanwhile, the way in which they learned English during the middle school period was basically translation- based teaching. Thus they have little or even no interest in English learning at all. In this way, discovering a new and interesting way with the aid of computer to learn English is of essential importance. Based on this, the paper discusses five major aspects under the circumstance of computer-assisted English learning. It is hoped that vocational college English teaching and learning can become more efficient by means of computer technology, finally students' English learning motivation and English competence can be enhanced to a great extent.
