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陈朋 《湖南第一师范学报》2012,12(4):112-116
提出一种基于Voronoi图的插值算法,通过采用邻近点查询法找出待插值节点的相关邻近节点,再根据邻近节点构建局部Delaunay三角网,并据此形成局部Voronoi图,将待插值点看成一个虚拟节点更新局部Voronoi图;依据各邻居节点的Voronoi面积和观测值计算出待插值点的预测数据;最后进行模拟实验,验证算法结果。 相似文献
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传统下垂控制没有考虑本地负荷和并联逆变器间线路阻抗等因素,无功功率不能实现准确分配,系统稳定性也会随之降低。为了实现对无功功率的合理分配,在微网系统传统下垂控制算法基础上,在电压电流双闭环控制中设计虚拟阻抗,以降低有功和无功耦合程度。然后针对低压微电网中线路阻性成分较大的问题,设计虚拟负阻抗的下垂控制算法,从而进一步降低了有功和无功耦合程度。仿真结果表明,改进下垂控制前后均可以实现对有功功率的合理分配。传统下垂控制的无功功率无法合理分配,偏差达到了 20%。加入虚拟阻抗控制算法后提高了无功功率分配精度,引入虚拟负阻抗的控制算法可使该精度进一步提高。因此,相比传统下垂控制,加入该控制算法后逆变器可以获得更好的功率分配效果。 相似文献
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为了缩减知识推理空间,提高分布式环境下知识处理的效率,提出分布式概念格属性约简的理论框架.基于粗糙集理论的思想,从子形式背景和全局形式背景的角度,刻画了核心属性、相对必要属性和绝对不必要属性的属性特征,给出属性约简的判定定理.在此基础上,给出概念格的分布式属性约简方法:首先,使用现有的约简方法分别计算各子形式背景的约简,然后,逐一利用各子背景的约简,通过合并计算得到全局形式背景的约简.给出了算法的实现并用实例验证了它的有效性.分布式约简有效避免了使用现有方法而引起的数据安全和网络通信等问题,提高了约简的计算效率. 相似文献
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针对现有对比度变换图像增强方法细节处理不足,经典穷举法和各种生物智能优化算法求取非完全Beta函数参数存在算法效率不高、易陷入局部最优的缺陷,提出一种利用非锐化掩膜局部细节提升能力和Beta变换全局对比度拉伸能力,简便快速且细节丰富的图像增强方法。使用不同灰度分布图进行仿真实验,结果表明该算法得到的增强图像直方图分布均匀、细节丰富且过渡自然平缓,算法效率高。 相似文献
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构建了在线迁移算法模型和虚拟机负载评估向量,并依据各物理节点的带宽占用率、内存占用率和CPU占用率,确定迁移时机和需要迁移的源物理节点,依据CPU在各节点的占有率、ROM的使用效率、带宽的利用率来确定目标物理节点。通过仿真模拟环境试验证明,文中算法在虚拟机在线迁移中能够大幅度地提高物理节点的负载均衡,同时SLA违反率最小和云计算数据中心能耗最小。 相似文献
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As a basic mathematical structure,the system of inequalities over symmetric cones and its solution can provide an effective method for solving the startup problem of interior point method which is used to solve many optimization problems.In this paper,a non-interior continuation algorithm is proposed for solving the system of inequalities under the order induced by a symmetric cone.It is shown that the proposed algorithm is globally convergent and well-defined.Moreover,it can start from any point and only needs to solve one system of linear equations at most at each iteration.Under suitable assumptions,global linear and local quadratic convergence is established with Euclidean Jordan algebras.Numerical results indicate that the algorithm is efficient.The systems of random linear inequalities were tested over the second-order cones with sizes of 10,100,,1 000 respectively and the problems of each size were generated randomly for 10 times.The average iterative numbers show that the proposed algorithm can generate a solution at one step for solving the given linear class of problems with random initializations.It seems possible that the continuation algorithm can solve larger scale systems of linear inequalities over the secondorder cones quickly.Moreover,a system of nonlinear inequalities was also tested over Cartesian product of two simple second-order cones,and numerical results indicate that the proposed algorithm can deal with the nonlinear cases. 相似文献
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INTRODUCTIONAutonomousnavigationisoneofthemostimportanttopicsinthemobilerobotareaandcanbecategorizedintotwoparts:reactivenavigation(Haddadetal.,1998)andpathplanning.Thefirstoneislocalpathplanningbasedandthesecondoneplansapathintheglobalworkspace .Localpat… 相似文献
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采用一种神经网络算法——径向基函数来选择无线传感器网络的节点簇首,它具有并行处理能力、分布式存储以及快速学习等优点.通过分析得出与节点作为簇首相关的4个因素:节点的剩余能量,周围分布的节点的数目,中心度和距离基站的位置.把这4个因素作为神经网络的输入变量,输出变量就是该节点作为簇首的适应度值.根据网络规模的大小,基站选出一组作为簇首的节点,然后广播作为簇首的节点号的消息.如果一个节点被选为簇首,就向周围广播自己的身份并成立一个新簇,周围的非簇首节点要求加入该簇并成为它的成员.每簇中由簇首负责管理它的成员并执行数据融合等功能.实验结果表明,与其他算法相比,该算法能显著地延长传感器网络的生命. 相似文献
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A novel robot navigation algorithm with global path generation capability is presented. Local minimum is a most intractable
but is an encountered frequently problem in potential field based robot navigation. Through appointing appropriately some
virtual local targets on the journey, it can be solved effectively. The key concept employed in this algorithm are the rules
that govern when and how to appoint these virtual local targets. When the robot finds itself in danger of local minimum, a
virtual local target is appointed to replace the global goal temporarily according to the rules. After the virtual target
is reached, the robot continues on its journey by heading towards the global goal. The algorithm prevents the robot from running
into local minima anymore. Simulation results showed that it is very effective in complex obstacle environments.
Project (No. 69904009) supported by the National Natural Science Foundation of China 相似文献
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To improve the handling performance of a steer-by-wire （SBW） vehicle, a series of control logics are proposed. Firstly, an algorithm for enhancing the maneuvering in steady-state cornering is presented. On this basis, two categories of control strategies are used to dynamically correct and compensate the transient state steering responses and vehicle behaviors. Simulator tests including subjective evaluations and virtual field tests are both conducted to make comprehensive investigations on the series of control logics. The subjective evaluations demonstrate that the SBW vehicle with a specifically selected value of steering sensitivity tends to be more desirable for driving than a conventional one in which a fixed steering ratio exists. The virtual field tests indicate that the control strategies for dynamical correction and compensation could effectively improve the handling per- formances of an SBW vehicle by reducing the work load of drivers, enhancingthe track-holding performance, and improving steering response properties. 相似文献
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The unintentional islanding of micro-grid may cause negative impacts on distribution loads and distributed generations, so it must be detected within the acceptable duration. In this paper a new islanding detection algorithm is proposed. This algorithm introduces the frequency feedback method by the reactive power compensation to derive the frequency continuous shift. Accordingly, the islanding can be detected by monitoring the frequency within 0.1 s. The simulationresults prove that this algorithm has extremely small non-detection zone, and meanwhile it presents an excellent islanding detection speed as well. 相似文献
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许邓艳卢民荣 《福建工程学院学报》2020,(4):358-364
提出基于反向随机局部投影的神经网络效率改进算法，通过降低深度学习中的网络规模，重点解决了从“局部连接”到“全连接”和随机节点抽取时输入端节点信息丢失的问题，从而提升网络的效率。在算法中设置缩减参数，提升了算法的可伸展性，以适用于不同数据集的学习。通过数据集ISO-LET进行实验，结果表明，基于反向随机局部投影的神经网络效率改进算法的准确率、效率分别平均提升了3.48%和105.21%?在迭代20次的实验中进行了缩减参数调节实验，当参数设置为1.4时其准确率则优于传统全连接网络2.61%，效率提升了272.78%，具有明显的优势。 相似文献
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为了提高分布式网络中各节点信任评价的准确度,提出了一种基于个体经验的信任模型.该模型通过引入经验因子和相对经验因子的方法,建立了新的信任评价体系.这种新的信任评价体系考虑了个体节点的差异问题,在计算节点的信任值时考虑了节点间的交互历史,这在一定程度上解决了由于节点的非对称性而导致的信任评价不准确的问题.算法分析表明:新模型能够针对不同的个体节点,采用不同的最大容忍评价偏差,并且对个体节点的反馈可信度进行更新时,采用不同的更新值,体现了节点的个性化特征,使信任评价更加准确合理.此外,所提出的新算法能够运用到多种信任模型中,具有很好的可扩展性. 相似文献
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针对具有时延的二阶多智能体系统领导—跟随异步脉冲一致性问题,假设每个多智能体采样邻接点信息的时刻互不相同,针对无向切换网络拓扑的多智能体系统,提出一种切换拓扑下有领导者的异步脉冲一致性控制协议。首先对该协议进行理论分析;然后构造 Lyapunov 函数,并利用 Lyapunov 稳定性理论与树形转换法给出多智能体系统在该控制协议下达到异步一致的充分条件;最后提出实例并进行 MATLAB 仿真。仿真结果表明,在脉冲控制下跟随者与领导者误差渐进趋于零,验证了该一致性协议有效性。 相似文献
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通过对数据仓库和分布式数据仓库体系构架的分析,得出当前分布式数据仓库存在的缺点：不能进行灵活的定制,易用性差。分布式数据仓库为了保持全局数据仓库和局部数据仓库的数据一致性,需购买大量昂贵的存储设备来保存两份相同的数据。针对这些缺点,提出了一种基于工作流的分布式数据仓库模型,模型的整体结构基于SOA面向服务的体系结构、分布式。引入了工作流技术来实现灵活定制数据提取需求、分析挖掘需求及结果可视化的需求,并将这些功能封装成整体模型中的业务流程服务。在业务流程服务模型部分提出了数据仓库业务流程执行语言、业务流程的可达性验证算法和优化算法。 相似文献
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提出了一种两阶段多功能光伏逆变器(QMFI),有功功率借助于该结构可以在一个功率转换器内从光伏阵列直接传输到电网或负载,从而提高转换效率。此外,考虑QMFI最大功率点跟踪(MPPT)的实现和非有功电流的补偿,提出了QMFI的数学模型,从而获得有效的控制参数。在求解过程中,采用基于旋转坐标系的分析模型,并推导了QMFI的空间矢量脉冲宽度调制策略,直观地揭示了非有功电流补偿对两阶段有功潮流的影响。最后,通过3 kVA样机验证了所提方案的可行性和有效性。 相似文献
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A clock synchronization method based on IEEE 1588 and its implementation on Ethernet 总被引：1，自引：0，他引：1
We presented a clock synchronization method that contained a clock adjusting algorithm and a frequency compensated clock to achieve precise synchronization among distributed clocks based on IEEE 1588 protocol. Further, we presented its application on Ethernet and implementation of the frequency compensated clock in a field programmable gate array （FPGA） as experiments. The results indicate that this method can support sub-microsecond synchronization with inexpensive standard crystal oscillators. 相似文献
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In order to improve efficiency of virtual enterprise, a manufacturing grid and multilevel manufacturing system of virtual enterprise is built up. When selecting member enterprises and task assignment based on the manufacturing grid, key activities are assigned to the suitable critical member enterprises by task decomposition, enterprise node searching and characteristic matching of manufacturing resources according to the characteristic matching strategy. By task merger, some ordinary activities are merged with corresponding key activities and assigned to corresponding critical member enterprises. However, the other ordinary activities are assigned to the related ordinary member enterprises with enterprise node searching and characteristic matching of manufacturing resources. Finally, an example of developing the artificial hip joint in the virtual enterprise is used to demonstrate that efficiency of the virtual enterprise is improved by using the manufacturing grid and the proposed strategies for member enterprise selection and task assignment. 相似文献
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According to the features of the turning simulation, a simplified Whitted lighting model is proposed based on the analysis of Phong and other local illumination model. Moreover, in order to obtain the natural lighting effects, local ray tracing algorithm is given to calculate the light intensity of every position during the course of the simulation. This method can calculate the refresh area before calculating the intersection line,simulate the machining environment accurately and reduce the calculating time. Finally, an example of the virtual cutting scene is shown to demonstrate the effects of the global illumination model. If the CUP is 1.3 G and the internal memory is 128 M, the refreshing time of virtual turning scene can be reduced by nine times. This study plays an important role in the enrichment of the virtual manufacturing theory and the promotion of the development of the advanced manufacturing technology. 相似文献