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181.
针对高超声速飞行器飞行过程中存在的高度非线性、强耦合、参数不确定性等问题提出了一种基于滑模边界层模糊自适应的控制方法;首先将纵向模型进行精确线性化,通过引入一个滑模边界层可调参数,在边界层外施加基于正切趋近律的准滑模控制律;在边界层内,去掉准滑模控制律,采用饱和函数法设计的控制律;边界层参数用模糊逻辑系统进行在线调节,从而消除了系统处于准滑动模态时的高频抖振;仿真结果表明:该方法在保证控制系统具有良好跟踪性能的同时,具有削弱抖振的能力和强鲁棒性。 相似文献
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本文着重分析了社交网站常见的法律问题,并通过比较研究各国的做法,试图总结出我国加强社交网站管理的监管措施。 相似文献
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王春涛 《数码设计:surface》2010,(7):152-154
动画素描表现形式与技法具有绘画艺术的普遍共性特征,多角度全方位理解与掌握人体造型与运动规律,简洁准确地表现人物的形体特征,将写生能力与形象记忆能力相结合并同步提高,为创造形象和专业学习打好基础。 相似文献
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E.A. Galperin 《Computers & Mathematics with Applications》2011,62(2):709-724
The special relativity considered in [A. Einstein, Zur Elektrodynamik der bewegte Körper. Ann. Physik, 17 (1905) 891-921] is based on the concept of finite speed of information transmittal by the available signals (rays of light). It is demonstrated that the same concept applies to Newton’s law of universal gravitation since the magnitude of distances between attracting masses can be physically defined (carried, accounted in acting forces of gravity) only by signals (physical processes) propagating at finite velocities. It follows that the speed of propagation of gravity is finite. The linear transformations of special relativity are applied to Newton’s law of gravitation to take into account the relativistic effects of information transmittal in a field of central forces of attraction. Relativistic representations of Newton’s law are obtained with respect to the center of gravity exposing illusory effects that appear at high velocities. It is verified that in atomic physics the effect of Newtonian gravitation on the motion of elementary particles at high velocities is negligible also in relativistic consideration. Computational methods are developed to measure the intensity of gravitation at a distant space-time location using a body that travels in space, emitting uniform pulses of light that are received by the observer at a different space-time location. It is demonstrated that the tensor approach to the general relativity and the united theory of space, time and gravitation in which the geometrical properties (metric) of the four-dimensional space-time continuum depend on the distribution of gravitating masses in space and their motion represent a transformed Lorentz invariant with a new type of inertia in the field of forces changing in space and time. Real physical processes evolve according to the forces represented in the tensor form by this invariant which is equivalent to the coordinate-free local invariant of relativistic dynamics that defines the field and the motion of a body whose velocities and accelerations can be measured by relativistic identification methods at a point, time and direction of interest. The results open new avenues for research in the general relativity and can be used for software development, field measurements and experimental studies in application to distant or fast moving systems. 相似文献
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Software execution processes as an evolving complex network 总被引:2,自引:0,他引:2
Inspired by the surprising discovery of several recurring structures in various complex networks, in recent years a number of related works treated software systems as a complex network and found that software systems might expose the small-world effects and follow scale-free degree distributions. Different from the research perspectives adopted in these works, the work presented in this paper treats software execution processes as an evolving complex network for the first time. The concept of software mirror graph is introduced as a new model of complex networks to incorporate the dynamic information of software behavior. The experimentation paradigm with statistical repeatability was applied to three distinct subject programs to conduct several software experiments. The corresponding experimental results are analyzed by treating the software execution processes as an evolving directed topological graph as well as an evolving software mirror graph. This results in several new findings. While the software execution processes may demonstrate as a small-world complex network in the topological sense, they no longer expose the small-world effects in the temporal sense. Further, the degree distributions of the software execution processes may follow a power law. However, they may also follow an exponential function or a piecewise power law. 相似文献