主动自调度集群的自调度算法

ASAS集群采用了基于后端服务器负载分析后的主动调度策略,在后端主动调度时计算后端服务器的负载,包括CPU利用率、内存利用率、I/O速度等,然后把上述几个方面划分为底(L)、中(M)、高(L)三个语言变量后,通过模糊数学理论,选取适当隶属函数,把实时状态隶属于以上三个语言变量的隶属函数值求出,并得出隶属矩阵.根据合适的算法得出后端执行服务器申请的连接数(容量Capacity),整个过程是基于负载动态反馈的.实验证明,该调度策略取得了比一般集群调度策略更优的效果.     

具有自适应通信能力的无线传感网节点设计

具有自适应通信能力的无线传感网节点的系统设计方案,实现了具有环境适应性、灵活高效、小体积低功耗的传感节点。     

无线传感器网络操作系统调度策略

提出了一种在无线传感器网络操作系统中可以同时针对周期性任务和非周期性任务进行抢占式调度操作的EF-RM调度策略。在无线传感器节点上执行的任务负载较重的情况下，该调度策略可以保证重要任务的优先执行，此外当无线传感器节点空闲时，通过将节点带入睡眠状态，实现无线传感器节点的节能。所提出的任务调度策略在TinyOS上进行实现，并通过实验测试得出，在总能耗代价增加较少的情况下可以有效地提高系统在较重负载情况下的响应性能。     

论CSMA/CD协议的数学原理

CSMA/CD 网络在长期试错中已经从单总线型网络发展到了堆叠式网络, 但其不确定性本质上并未得到解决. 本文从数学原理角度推导了其不确定性解决的理论依据, 通过对堆叠式网络数学模型的抽象, 证明了堆叠式网络结构服从幂率变换定理, 在其时间敏感性上以幂率收敛方式优于单总线型网络, 并从网络吞吐量和网络传输效率性能分析评价了该模型. 最后, 总结出了CSMA/CD 的理论``究竟', 拓宽了CSMA/CD 在嵌入式工业控制领域的``方便' 应用.     

基于最小开关损耗的SVPWM调制技术

分析了空间电压矢量（SVPWM）的基本原理，给出了SVPWM技术的几种优化措施，并在此基础上提出一种根据负载功率因数角动态分配零矢量的方法。理论分析和仿真结果表明。采用该方法能达到最小开关损耗。     

神经网络集成融合模型研究及应用

针对专家系统等单一模型解决发动机故障诊断存在的算法复杂度高、诊断准确率低等问题，提出了BP神经网络集成与DS证据推理相融合的神经集成融合模型，不仅实现了发动机不同部位的专家经验与实际观测数据的特征级融合，还实现了多个模型的优势互补。通过对该方法和传统的专家系统方法比较得出，神经网络集成融合方法提高了7.1%的诊断准确率。     

Multi-object trajectory tracking

The majority of existing tracking algorithms are based on the maximum a posteriori solution of a probabilistic framework using a Hidden Markov Model, where the distribution of the object state at the current time instance is estimated based on current and previous observations. However, this approach is prone to errors caused by distractions such as occlusions, background clutters and multi-object confusions. In this paper, we propose a multiple object tracking algorithm that seeks the optimal state sequence that maximizes the joint multi-object state-observation probability. We call this algorithm trajectory tracking since it estimates the state sequence or “trajectory” instead of the current state. The algorithm is capable of tracking unknown time-varying number of multiple objects. We also introduce a novel observation model which is composed of the original image, the foreground mask given by background subtraction and the object detection map generated by an object detector. The image provides the object appearance information. The foreground mask enables the likelihood computation to consider the multi-object configuration in its entirety. The detection map consists of pixel-wise object detection scores, which drives the tracking algorithm to perform joint inference on both the number of objects and their configurations efficiently. The proposed algorithm has been implemented and tested extensively in a complete CCTV video surveillance system to monitor entries and detect tailgating and piggy-backing violations at access points for over six months. The system achieved 98.3% precision in event classification. The violation detection rate is 90.4% and the detection precision is 85.2%. The results clearly demonstrate the advantages of the proposed detection based trajectory tracking framework.     

Tribological Behaviour of the Ceramic Coating Formed on Magnesium Alloy

Micro-arc oxidation is a recently developed surface treatment technology under anodic oxidation. Through micro-arc oxidation, a ceramic coating is directly formed on the surface of magnesium alloy, by which its surface property is significantly improved. In this paper, a dense ceramic oxide coating was prepared on an AZ31 magnesium alloy by micro-arc oxidation in a NaOH-Na2SiO3-NaB407-（NaPO3）6 electrolytic solution. Micro-structure, surface morphology and phase composition were analysed using scanning electron microscopy （SEM） and X-ray diffraction （XRD）. The tribological behavior of the micro-arc oxidation ceramic coating under dry sliding against GCr15 steel was evaluated on a ball-on-disc test rig. The results showed that the AZ31 alloy was characterized by adhesion wear and scuffing under dry sliding against the steel, while the surface micro-arc oxidation ceramic coating experienced much abated adhesion wear and scuffing under the same testing conditions. The micro-arc oxidation ceramic coating showed good friction-reducing and fair antiwear ability in dry sliding against the steel.     

一种基于TDMA的Ad Hoc网络的虚电路建立协议

为了实现网络中端到端的可靠传输,在基于TDMA的Ad Hoc网络里引入一种虚电路建立协议.该协议采用分布式的资源预约方式建立虚电路,对于网络拓扑变化所引起的链路故障,能够及时发现和处理,且具有相对较小的开销和较高的可靠性,比较适合Ad Hoc网络.     

基于网格的一种安全组播密钥分配策略

在网格中,组播是实现大规模信息资源共享的一种重要方式,然而,如何保障组播的安全性是一个十分复杂的问题.本文将以集中控制和分布式管理所采用的密钥管理策略为基础,在遵循网格组播机制的前提下,考虑成员动态变化因素,提出了分层方法、成员发现协议、分簇协议和密钥分配策略,从而形成了一种基于网格的安全组播密钥分配策略.仿真实验结果表明此密钥分配策略具有良好的可行性和有效性.