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排序方式: 共有778条查询结果,搜索用时 15 毫秒
1.
This investigation proposes a fixed collision rate (FCR) back-off algorithm for wireless networks. The proposed scheme takes advantage of the central unit (CU) in a wireless network to broadcast a common back-off window size to all the users, significantly alleviating the unfairness of bandwidth utilization in conventional binary exponential back-off (BEB) algorithms. It is shown that, when maximum throughput is achieved, collision rate is almost a constant for any traffic load. In the operation of the FCR, the CU dynamically adjusts the back-off window size to keep the collision rate at a constant level for maximum throughput. Simulation results demonstrate that the unfairness of bandwidth utilization in the BEB is significantly lessened and the throughput can be maintained at e-1≈0.368 when the number of users approaches infinity. The capture effect even further improves system performance. 相似文献
2.
Yueqi Zhong 《Computer aided design》2006,38(10):1062-1073
This paper introduces a new method of generating 2D flat patterns from a 3D triangulated surface by opening the bending configuration of each winged triangle pair. The flattening can be divided into four steps. First, a 3D triangulated surface is modeled with a mass-spring system that simulates the surface deformation during the flattening. Second, an unwrapping force field is built to drive the mass-spring system to a developable configuration through the numerical integration. Third, a velocity redistribution procedure is initiated to average velocity variances among the particles. Finally, the mass-spring system is forced to collide with a plane, and the final 2D pattern is generated after all the winged triangle pairs are spread onto the colliding plane. To retain the size and area of the original 3D surface, a strain control mechanism is introduced to keep the springs from over-elongation or over-shrinkage at each time step. 相似文献
3.
张健 《电脑编程技巧与维护》2012,(18):56-57,107
由于TCP协议直接应用到卫星网络中将可能会导致网络性能下降,因此针对卫星网络的特点,分析了传播时延、高误码率、非对称连接方式等特点对TCP协议性能的影响,对主要解决方法进行了分析、比较现有的几种解决方法利弊,应根据具体应用采用相应的解决方案。 相似文献
4.
E. Duffour 《Polymer》2004,45(13):4565-4575
To allow a better understanding of the physical phenomena occurred between a plasma and an insulating material, we have developed a specific MD code to study this type of interaction. We report results of MD simulations of the interaction of an incoming copper ion with a polyethylene crystal surface. Three initial incoming velocities and four impact angle values are used to check the influence of both the incident energy and impact direction to the resulting surface damage. When the incoming ion velocity is sufficiently high, MD results show that the impact can cause bond breaking leading to uncoordinated carbon atoms and free hydrogen atoms. The values of local temperatures associated with the structural changes show a possible ablation of the polyethylene surface. 相似文献
5.
黄吉兰 《电脑与微电子技术》2014,(11):78-80
在飞行射击游戏框架设计与实现过程中,分析游戏的场景设计、物体之间碰撞的处理、游戏角色和整个游戏类的框架并对程序流程进行描述。实现游戏UI的设计、背景的载人、角色的设计和实例化。在Android系统中对该游戏进行反复测试,实现飞行射击游戏。 相似文献
6.
一种快速的基于球体混合重建的碰撞检测算法 总被引:1,自引:0,他引:1
为了解决虚拟特征和虚拟环境中虚拟物体的相交问题,必须对实时的虚拟应用环境实施快速的碰撞检测.提出了基于球体混合重建的碰撞检测算法,对球体混合表面提出了一个子线性时间复杂性的重建过程;利用四元组构造变换范围,扩展了从线性到球形混合的构造变换方法;采用循环划分的方法完成了由球体混合到线性混合的分解过程.尽管这个方法的实现过程较线性的方法更难些,但算法的执行过程所需时间却与线性方法相差无几,其复杂性也与线性结构的相同. 相似文献
7.
This paper studies a non-reciprocal swarm model that consists of a group of mobile autonomous agents with an attraction-repulsion function governing the interaction of the agents. The function is chosen to have infinitely large values of repulsion for vanishing distance between two agents so as to avoid occurrence of collision. It is shown analytically that under the detailed balance condition in coupling weights, all the agents will aggregate and eventually form a cohesive cluster of finite size around the weighted center of the swarm in a finite time. Moreover, the swarm system is completely stable, namely, the motion of all agents converge to the set of equilibrium points. For the general case of non-reciprocal swarms without the detailed balance condition, numerical simulations show that more complex self-organized oscillations can emerge in the swarms. The effect of noise on collective dynamics of the swarm is also examined with a white Gaussian noise model. 相似文献
8.
Key challenges found in some facilities maintenance (FM) operations include the dependency on placing sophisticated workers in undesirable working conditions that could make them susceptible to accidents. Robot-assisted in-situ facilities maintenance represents new opportunities by assisting human operators when exposed to harsh environments. However, given the complexities and potential varieties of advanced robotic machinery available for use in facility maintenance workplaces in the future, there is still a legitimate risk of collisions between future robotic systems and the facility structure during the robot-assisted processes. This paper proposes and tests a simulation-based collision-free design method for future facilities that may be benefited from a robot-assisted FM process. At the most fundamental level, we consider interactions between the articulated manipulator (robot) and the surrounding facility structure. Inverse Kinematics (IK) and game engines are used to simulate the possible collisions between a given robot and the parameterized facility layout. To account for the uncertainty about the kinematic specifications of the future robotic machinery, a Monte Carlo method is used to model unique priority circumstances for each joint on the articulated manipulator. The simulation result, presented as the robot work zone envelope, is then used to estimate the collision probability given a certain design parameter, and the corresponding optimal design that balances the initial construction cost and the FM costs. The method is assessed for identifying a 3D spatial collision probability cloud within reach of a 7 DOF articulated manipulator that is marginally positioned within a pressure valve piping facility. These insights can provide future facility designers, managers, and equipment operators with a quick and flexible 3D spatial collision probability indicator to better design the facility and proximity limitations of any articulated manipulator positioned throughout a confined space for future robot-assisted FM processes. 相似文献
9.
We present an efficient algorithm for collision detection between static rigid objects using a dual bounding volume hierarchy which consists of an oriented bounding box (OBB) tree enhanced with bounding spheres. This approach combines the compactness of OBBs and the simplicity of spheres. The majority of distant objects are separated using the simpler sphere tests. The remaining objects are in close proximity, where some separation axes are significantly more effective than others. We select 5 from among the 15 potential separating axes for OBBs. Experimental results show that our algorithm achieves considerable speedup in most cases with respect to the existing OBB algorithms. 相似文献
10.
苏仰娜 《计算机应用与软件》2010,27(5):260-263
在分析碰撞检测算法图像空间法与对象空间法各有优劣的基础上,以提高碰撞检测的完全性、唯一性与实时性为目标,提出一种基于图像空间法与对象空间法相结合的A缓冲碰撞检测算法。利用CULLIDE算法的实时性及AABB算法精确性相结合的优点,以A缓冲单元控制精度,可根据不同场景的需要控制A缓冲单元的尺寸。因不需要预处理,避免了不必要的重叠检测,能简单地被硬件加速,其速度比普通的方法约快8倍的速度。不仅适应于刚体与软体模型,而且能够检测自我冲突。 相似文献