可调自适应三角网格的细分曲面造型方法

为了研究一种简单的有效的细分曲面方法使生成的曲面不仅光滑而且可调,提出了一种面向三角网格的可调自适应细分曲面造型法,该方法通过在传统的Loop细分模式中加入形状控制因子以使生成的曲面形状可调,同时引入二面角作为控制误差来判断相邻三角形夹角是否满足给定的阈值,以此实现自适应细分过程。模拟算例结果表明,该方法不仅能用较少网格获得性能良好的曲面,而且可以通过选取不同的值调整生成曲面形状,满足工程需要。     

模糊支持向量机建筑物边缘特征提取方法研究

为解决边缘点与非边缘点过渡的模糊边缘,提出了一种模糊支持向量机的边缘检测算法。该算法选用图像3 3窗口4个方向的灰度梯度、梯度幅值和梯度方向组成6维特征向量,同时选用径向机核函数对样本特征向量升维到高维空间,在高维空间中构造最优分类超平面。同时,根据归一化后的梯度幅值来确定每个样本的隶属度,最后利用模糊支持向量机实现边缘检测。实验结果表明了模糊支持向量机边缘检测方法的可行性。     

面向跨组织业务流程的角色行为验证方法

为了更有效地保证跨组织业务流程模型的正确性和合理性,应用Pi演算提出了一种基于状态的角色行为的验证方法。基于Pi演算提出了跨组织业务协作中的角色模型,设计了角色描述表,以清晰、直观地描述角色的权利、职责和义务,进而应用Pi演算验证工具MWB(移动工作平台)的check和step命令提出了单角色验证方法,并在此基础上从业务对象状态和业务操作角度提出了多角色验证方法。实现了角色行为的验证,并为跨组织业务流程的可达性、一致性和死锁等分析奠定基础。     

基于CAN总线星务仿真系统的设计与实现

综合考虑研制成本以及卫星在轨运行的可靠性和安全性,使用PCI1680 CAN总线控制卡作为主控节点,模拟小卫星星务系统.系统采用双总线冗余设计来提高可靠性,根据特定的组帧解帧协议实现遥控/遥测功能,同时具备电压采集和电源控制功能,为小卫星系统提供全面、通用的地面测试和调试环境.     

PCB检测中图像分割技术研究

光学检测是进行印刷电路板(PCB)装配质量检验的重要手段,应用图像分割技术可以提取PCB中的目标物以进行检测。针对PCB图像分割,提出一种基于改进量子遗传算法的图像分割方法。该方法将基于阈值的图像分割方法转化为阈值优化问题,通过改进量子遗传算法的计算实现最优图像分割阈值的求取。仿真结果验证了该方法的可行性。     

Faster Deterministic Communication in Radio Networks

We study the communication primitives of broadcasting (one-to-all communication) and gossiping (all-to-all communication) in known topology radio networks, i.e., where for each primitive the schedule of transmissions is precomputed based on full knowledge about the size and the topology of the network. We show that gossiping can be completed in time units in any radio network of size n, diameter D, and maximum degree Δ=Ω(log n). This is an almost optimal schedule in the sense that there exists a radio network topology, specifically a Δ-regular tree, in which the radio gossiping cannot be completed in less than units of time. Moreover, we show a schedule for the broadcast task. Both our transmission schemes significantly improve upon the currently best known schedules by Gąsieniec, Peleg, and Xin (Proceedings of the 24th Annual ACM SIGACT-SIGOPS PODC, pp. 129–137, 2005), i.e., a O(D+Δlog n) time schedule for gossiping and a D+O(log ³ n) time schedule for broadcast. Our broadcasting schedule also improves, for large D, a very recent O(D+log ² n) time broadcasting schedule by Kowalski and Pelc. A preliminary version of this paper appeared in the proceedings of ISAAC’06. F. Cicalese supported by the Sofja Kovalevskaja Award 2004 of the Alexander von Humboldt Stiftung. F. Manne and Q. Xin supported by the Research Council of Norway through the SPECTRUM project.     

八通道可变增益高速数据采集系统

针对多通道超声波应用提出了一种USB+FPGA+DSP的架构,模拟前端可实现8通道高速数据采集,并可实现线性增益和可变采样率。FPGA为系统的控制核心,同时进行信号预处理方面的工作,而DSP着重于复杂算法的应用。最后通过已知信号对整个系统进行测试,验证了该系统性能良好,具有很高的实用价值。     

飞思卡尔推出一站式32位工业连接解决方案简化嵌入式开发

<正>嵌入式开发人员面临着用更少资源做更多事情的压力,他们不但要增强性能应用和连通性,而且要降低成本,加快产品上市。为了帮助开发人员成功应对设计     

Design and fault diagnosis of Petri net controllers for Petri nets with uncontrollable and unobservable transitions

This paper presents a methodology for diagnosing faults of controllers which are modeled by Petri nets with uncontrollable and unobservable transitions. The inadmissible constraints with uncontrollable and unobservable transitions are transformed into admissible conditions in this method. And we can design controllers easily using reduction technique. In order to provide tolerance against faults in controllers, we embed the given Petri net controller into a larger Petri net controller that retains the functionality of original controllers, and encode the large Petri net controller. Separate redundant Petri net controllers using additional places, connections and tokens to impose invariant conditions allow the systematic detection and identification of faults via Hamming code. The proposed method is attractive because it can check faults (place faults, transition faults or mixed faults) easily. A manufacturing cell is taken as an example to illustrate the approach.     

Symmetric active/active metadata service for high availability parallel file systems

High availability data storage systems are critical for many applications as research and business become more data driven. Since metadata management is essential to system availability, multiple metadata services are used to improve the availability of distributed storage systems. Past research has focused on the active/standby model, where each active service has at least one redundant idle backup. However, interruption of service and even some loss of service state may occur during a fail-over depending on the replication technique used. In addition, the replication overhead for multiple metadata services can be very high. The research in this paper targets the symmetric active/active replication model, which uses multiple redundant service nodes running in virtual synchrony. In this model, service node failures do not cause a fail-over to a backup and there is no disruption of service or loss of service state. A fast delivery protocol is further discussed to reduce the latency of the total order broadcast needed. The prototype implementation shows that metadata service high availability can be achieved with an acceptable performance trade-off using the symmetric active/active metadata service solution.