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301.
面对旅游人才日益明显的供需矛盾和学生职业意识淡薄的现状,高职院校旅游管理专业学生职业意识的培养日益受到重视。依托湖南民族职业学院的光大公司和华夏民族文化风情园,开展校企一体办学模式下以"双师双能"的师资建设为龙头,以"体验式·参与式"的实践教学体系建设为核心,以融入职业核心能力和企业文化的校本实训教材开发为载体的高职旅游管理专业人才职业意识培养模式的新探索。 相似文献
302.
Optimization of geosynchronous satellite constellation for independent regional navigation and positioning in Middle East region 总被引:1,自引:0,他引:1
Regional Navigation and positioning systems using geosynchronous satellites are emerging for different parts of the world. Optimal constellation geometry achievement for a set of geosynchronous satellites is a key sector in designing of such systems. Genetic algorithm is applied for optimization of constellations with 6 and 7 satellites which is to be used in Middle East region where these systems have been deprived of. Based on the fact that the coverage criterion is not sufficient enough to guarantee a good navigation service, positioning process by the satellite systems is discussed and the performance of the system on the basis of position dilution of precision is collected as the fitness criterion. Placing the satellites in groups to pass over the same ground track is applied as a constraint to the genetic algorithm. By simulation, performance of the best obtained results and GPS are compared in terms of position dilution of precision, visibility and the required epochs (time span) to resolve the ambiguities with a 99% success rate, in this region. Also, capability of the GA for such problems is demonstrated. 相似文献
303.
V.V. Kalegaev I.I. Alexeev I.S. Nazarkov V. Angelopoulos A. Runov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2014
The magnetic field structure and the spatial characteristics of the large-scale currents in the magnetospheric tail were studied during quiet and moderately disturbed geomagnetic conditions in 2009. The magnetic field of the currents other than the tail current was calculated in terms of a paraboloid model of the Earth’s magnetosphere, A2000, and was subtracted from measurements. It was found on the base of obtained tail current magnetic field radial distribution that the inner edge of the tail current sheet is located in the night side magnetosphere, at distances of about 10 RE and of about 7 RE during quiet and disturbed periods respectively. During the disturbance of February 14, 2009 (Dstmin ∼ −35 nT), the Bx and the Bz component of the tail current magnetic field near its inner edge were about 60 nT, and −60 nT that means that strong cross-tail current have been developed. The tail current parameters at different time moments during February 14, 2009 have been estimated. Solar wind conditions during this event were consistent with those during moderate magnetic storms with minimum Dst of about −100 nT. However, the magnetospheric current systems (magnetopause and cross-tail currents) were located at larger geocentric distances than typical during the 2009 extremely quiet epoch and did not provide the expected Dst magnitude. Very small disturbance on the Earth’s surface was detected consistent with an “inflated” magnetosphere. 相似文献
304.
基于模型的系统工程方法在载人航天任务中的应用探讨 总被引:1,自引:0,他引:1
针对基于文档的航天任务设计中设计数据分散、一致性差、跟踪难度大等问题,引入了基于模型的系统工程(MBSE)方法。首先,介绍了MBSE方法理念,即通过构建图形化的模型来支持系统的需求捕获、设计、分析、验证和确认等全生命周期活动。然后,给出了MBSE方法的一般工作流程,即先构建系统的需求模型,用于指导功能模型、物理架构模型等的构建,按照事先制定好的逻辑规则建立模型间的关系,依靠模型间的关系实现设计过程中的关联性分析、参数查询等工作。最后,应用MBSE方法于载人飞船交会对接任务中。结果表明,此方法改善了人员沟通,提高了设计效率,降低了设计风险,可为MBSE方法在航天任务设计中的进一步应用提供参考。 相似文献
305.
306.
捷联式天线稳定平台动力学建模与仿真分析 总被引:7,自引:1,他引:6
对于体积有限制的战术导弹应用,导引头天线伺服系统的体积受到严格限制,传统的速率陀螺稳定平台的应用受到挑战,为此提出采用捷联稳定方式来解决视线稳定问题.根据弹载捷联式天线平台的结构特点及稳定原理,应用坐标变换方法,完整地建立了两自由度捷联式天线平台的运动学与动力学模型.通过分析平台框架运动学耦合关系,表明捷联稳定方式与速率陀螺稳定方式的基本区别在于信息的获取和控制方式上,速率陀螺稳定方式是一种直接硬件稳定方法,而捷联稳定方式是一种软件补偿方法.在此基础上,对框架动力学耦合特性进行了数值仿真,结果表明:弹体对框架的耦合较强,需要进行弹体解耦,而框架之间的交叉耦合相对较弱,实际设计时可以忽略.所得结果为进一步研究捷联式天线稳定平台提供了理论基础,也为小型化导引头视线稳定平台系统的工程设计提供了一种解决方案. 相似文献
307.
针对转移概率部分未知情况下的离散时间广义Markov跳变系统,研究了系统的稳定性和镇定性。转移概率部分未知的情况包含了转移概率完全已知和完全未知两种特殊情况,具有更广泛的实际意义。首先利用线性矩阵不等式方法,将离散Markov跳变系统的结论推广到离散广义Markov跳变系统,提出了使开环系统随机稳定的充分条件;在此基础上,进一步提出了闭环系统可镇定的判据,并表示为线性矩阵不等式形式;最后,通过仿真算例验证了所提方法的有效性。 相似文献
308.
Rodrigo A. Miranda Abraham C.-L. Chian Erico L. Rempel 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
We analyze the multifractal scaling of the modulus of the interplanetary magnetic field near and far upstream of the Earth’s bow shock, measured by Cluster and ACE, respectively, from 1 to 3 February 2002. The maximum order of the structure function is carefully estimated for each time series using two different techniques, to ensure the validity of our high-order statistics. The first technique consists of plotting the integrand of the pth order structure function, and the second technique is a quantitative method which relies on the power-law scaling of the extreme events. We compare the scaling exponents computed from the structure functions of magnetic field differences with the predictions obtained by the She–Lévêque model of intermittency in anisotropic magnetohydrodynamic turbulence. Our results show a good agreement between the model and the observations near and far upstream of the Earth’s bow shock, rendering support for the modelling of universal scaling laws based on the Kolmogorov phenomenology in the presence of sheet-like dissipative structures. 相似文献
309.
310.
介绍了Collocation方法的原理及误差构成,以Collocation方法在逐历元滤波轨道解算中的应用为切入点对小步长低阶Collocation方法轨道积分的性能进行了研究。分别就二体问题及真实GPS星座卫星轨道为对象进行了一系列验算,得到了一些有益结论:就积分方法本身性能而言,Collocation积分方法较传统数值积分法精度要高且稳定性要好;在一定长度的积分步长范围内,将小步长低阶Collocation方法用于滤波轨道解算是可行且有效的。 但在积分步长很小的情形下,从计算效率方面考虑,不推荐使用Collocation方法;利用小步长低阶Collocation方法取代大步长高阶方法能提高效率且可抑制蚀现象引起的积分结果发散。经试验表明:选用积分步长为900s的4阶方法是合适的。 相似文献