两种级联空时格码方案的EXIT分析

级联空时格码方案可以有效地提高空时格码系统的性能。研究了两种级联空时格码方案:PC-STTC和ST-Turbo-TC。由于两种级联方案都使用了迭代译码方法,而外信息转移(EXIT)图是分析迭代译码性能的有利工具,主要分析比较了PC-STTC和ST-Turbo-TC的EXIT性能,比较了不同信噪比和编码多项式对于译码外信息转移特性的影响。研究结果显示,PC-STTC方案比ST-Turbo-TC方案有着更好的迭代收敛性能,同时给出了BER仿真图证明了EXIT图的分析结论。     

基于ZigBee的多机器人通信系统的设计

为解决多机器人协作的问题,设计了可以让机器人之间基于ZigBee网络进行通信的通信方案。机器人硬件系统中引入了ZigBee节点,多个机器人依赖ZigBee形成一个星型网络,每个机器人可以通过中心节点保持通信。实验结果表明,机器人之间可以可靠地进行通信,能够显著提高机器人的工作效率。     

Design and fabrication of novel micro electromagnetic actuator

This study designs, fabricates, and characterizes a novel micro electromagnetic actuator comprising a PDMS diaphragm, a polyimide-coated copper micro coil, and a permanent magnet. When an electrical current is passed through the micro coil, a magnetic force is induced between the coil and the magnet which causes the diaphragm to deflect, thereby creating an actuation effect. The experimental results demonstrate that the diaphragm deflection can be accurately controlled by regulating the current passed through the micro coil. It is shown that the maximum diaphragm deflection within elastic limits is 150 μm; obtained by passing a current of 0.6 A through a micro coil with a line width of 100 μm. The micro actuator proposed in this study is easily fabricated and is readily integrated with existing bio-medical chips due to its planar structure.     

异步数据传输机制（ACM）的有限状态机建模分析

介绍异步数据传输机制(Asynchronous Communication Mechanism,ACM)的基本理论,采用有限状态机理论建立ACM的抽象数学模型,通过此模型分析研究了ACM的相关特性,以及亚稳态问题对于这种机制的影响.ACM在异步模块间的数据传输等方面的应用具有突出的优势.     

智能仪表非线性自动校正方法研究

针对智能仪表不便于进行复杂计算、内存有限和实时性要求高等特点,在比较了几种常用的非线性校正方法的基础上,通过对智能仪表的非线性特性曲线的一般性分析,运用分段直线逼近曲线的方法,给出了一种通用的智能仪表非线性自动校正算法.同时讨论了该算法的原理、修正方法及校正参数的存储结构.并详细介绍了该算法在称重仪表中的具体应用.实践证明这种算法简单、实用,效果良好.     

ECMail:基于实体发现、查找和管理的中文邮件管理系统

随着个人用户的数据和信息级数增长,个人信息管理的研究成为热点.电子邮件作为个人信息的重要载体在个人信息业务中占据着重要的地位.随着个人信息的增加,用户在对邮件进行查询时经常遇到遗忘关键字的困扰,对此普通的邮件工具很难为用户组织和管理个人信息提供帮助.提出了一个基于实体发现、查找和管理的中文邮件管理系统--ECMail,有效改善了以上问题,同时对关键技术-中文分词、实体挖掘和实体关联管理的实现提出了自己的想法和处理机制,最终达到了提高用户邮件管理效率的目的.     

工作流资源分配中约束规则的建模研究

传统工作流系统在对任务节点进行资源分配时,只进行了组织、角色、人员的分配,而较少对不同任务节点上执行人间的潜在关系进行建模.根据企业的实际应用需求,将这种潜在的约束关系提取出来进行建模,并以规则的形式进行定义.最后采用强有力的推理工具--规则引擎--来完成对定义的规则冲突检测以及规则的实现.     

基于代理的工作流邦联及子流调用框架

在分析层次工作流建模和工作流执行时互操作研究的基础上,设计了一个基于代理的邦联及子流调用框架,将层次化建模技术、流程互操作技术和异构数据模型映射和转换技术集成在一起,同时提供了异常处理和灾难恢复功能,真正从业务层次上解决了流程协作问题,并在TiPLM2.9上实现了该解决方案.流程实例之间通过代理进行交互,各个流程独立运行在自己的工作流引擎中,实现了松耦合和隔离性,增强了系统健壮性.     

Improving Metadata Caching Efficiency for Data Deduplication via In-RAM Metadata Utilization

We describe a data deduplication system for backup storage of PC disk images, named in-RAM metadata utilizing deduplication (IR-MUD). In-RAM hash granularity adaptation and miniLZO based data compression are firstly proposed to reduce the in-RAM metadata size and thereby reduce the space overheads required by the in-RAM metadata caches. Secondly, an in-RAM metadata write cache, as opposed to the traditional metadata read cache, is proposed for further reducing metadata-related disk I/O operations and improving deduplication throughput. During deduplication, the metadata write cache is managed following the LRU caching policy. For each manifest that is hit in the metadata write cache, an expensive manifest reloading operation from the disk is avoided. After deduplication, all the manifests in the metadata write cache are cleared and stored on the disk. Our experimental results using 1.5 TB real-world disk image dataset show that 1) IR-MUD achieved about 95% size reduction for the deduplication metadata, with a small time overhead introduced, 2) when the metadata write cache was not utilized, with the same RAM space size for the metadata read cache, IR-MUD achieved a 400% higher RAM hit ratio and a 50% higher deduplication throughput, as compared with the classic Sparse Indexing deduplication system where no metadata utilization approaches are utilized, and 3) when the metadata write cache was utilized and enough RAM space was available, IR-MUD achieved a 500% higher RAM hit ratio compared with Sparse Indexing and a 70% higher deduplication throughput compared with IR-MUD with only a single metadata read cache. The in-RAM metadata harnessing and metadata write caching approaches of IR-MUD can be applied in most parallel deduplication systems for improving metadata caching efficiency.     

Dynamic Shortest Path Monitoring in Spatial Networks

With the increasing availability of real-time traffic information, dynamic spatial networks are pervasive nowadays and path planning in dynamic spatial networks becomes an important issue. In this light, we propose and investigate a novel problem of dynamically monitoring shortest paths in spatial networks (DSPM query). When a traveler aims to a destination, his/her shortest path to the destination may change due to two reasons: 1) the travel costs of some edges have been updated and 2) the traveler deviates from the pre-planned path. Our target is to accelerate the shortest path computing in dynamic spatial networks, and we believe that this study may be useful in many mobile applications, such as route planning and recommendation, car navigation and tracking, and location-based services in general. This problem is challenging due to two reasons: 1) how to maintain and reuse the existing computation results to accelerate the following computations, and 2) how to prune the search space effectively. To overcome these challenges, filter-and-refinement paradigm is adopted. We maintain an expansion tree and define a pair of upper and lower bounds to prune the search space. A series of optimization techniques are developed to accelerate the shortest path computing. The performance of the developed methods is studied in extensive experiments based on real spatial data.