变精度复合粗糙集模型及其应用*

针对复合信息系统中的噪声数据以及复合粗糙集近似边界要求严格等问题,对复合粗糙集模型进行了扩展,提出变精度复合粗糙集模型。在该模型中,通过设置阈值参数β (0.5<β ≤1),定义了基于矩阵方法的变精度复合粗糙集的β-上近似、β-下近似、β-正区域、β-负区域、β-边界区域、β-精确度和β-粗糙度等概念;同时,对变精度复合粗糙集的相关性质进行了研究。最后,通过实例说明了该模型在信息处理中的应用,进一步说明该模型具有一定的容错性,抗干扰能力增强,应用范围扩大。     

基于SVM的特征筛选方法及其若干应用

对于拟合问题，传统的模式识别特征筛选方法以各特征量对训练数据拟合能力的贡献为取舍标准，未考虑经验风险最小化和结构风险最小化间的差别，不能获得预报能力最强的特征筛选结果。为此我们提出了结合支持向量回归法与留一法的特征筛选新算法，并将它试用于镍氢电池材料和氧化铝溶出率两套实验数据集的特征筛选。     

A practical method for patterning lumens through ECM hydrogels via viscous finger patterning

Extracellular matrix (ECM) hydrogels with patterned lumens have been used as a framework to generate more physiologically relevant models of tissues, such as vessels and mammary ducts, for biological investigations. However, these models have not found widespread use in research labs or in high-throughput screening applications in large part because the basic methods for generating the lumen structures are generally cumbersome and slow. Here we present viscous finger patterning, a technique to generate lumens through ECM hydrogels in microchannels that can be accomplished using manual or automated pipetting. Passive pumping is used to flow culture media through an unpolymerized hydrogel, creating a lumen through the hydrogel that is subsequently polymerized. Viscous finger patterning takes advantage of viscous fingering, the fluid dynamics phenomenon where a less viscous fluid will flow through and displace a more viscous fluid. We have characterized the technique and used it to create a variety of channel geometries and ECM hydrogel compositions, as well as for the generation of lumens surrounded by multiple hydrogel layers. Because viscous finger patterning can be performed with automated liquid handling systems, high-throughput generation of ECM hydrogels with patterned lumen is enabled. The ability to rapidly and cost-effectively create large numbers of lumens in natural polymers overcomes a critical barrier to the use of more physiologically relevant tissue models in a variety of biological studies and drug screening applications.     

A computer-controlled near-field electrospinning setup and its graphic user interface for precision patterning of functional nanofibers on 2D and 3D substrates

Electrospinning is a versatile technique for production of nanofibers. However, it lacks the precision and control necessary for fabrication of nanofiber-based devices. The positional control of the nanofiber placement can be dramatically improved using low-voltage near-field electrospinning (LV-NFES). LV-NFES allows nanofibers to be patterned on 2D and 3D substrates. However, use of NFES requires low working distance between the electrospinning nozzle and substrate, manual jet initiation, and precise substrate movement to control fiber deposition. Environmental factors such as humidity also need to be controlled. We developed a computer-controlled automation strategy for LV-NFES to improve performance and reliability. With this setup, the user is able to control the relevant sensor and actuator parameters through a custom graphic user interface application programmed on the C#.NET platform. The stage movement can be programmed as to achieve any desired nanofiber pattern and thickness. The nanofiber generation step is initiated through a software-controlled linear actuator. Parameter setting files can be saved into an Excel sheet and can be used subsequently in running multiple experiments. Each experiment is automatically video recorded and stamped with the pertinent real-time parameters. Humidity is controlled with ±3% accuracy through a feedback loop. Further improvements, such as real-time droplet size control for feed rate regulation are in progress.     

一种分布式Twitter数据处理方案及应用

针对社交媒体数据的特点及其分析的挑战性,提出了一种基于实时计算框架Storm、批处理框架Hadoop和高效可水平扩展的NoSQL数据库MongoDB的分布式社交媒体数据处理方案,并依此指导实现基于Twitter流式数据的流感疫情可视化分析系统.实验证明,该分布式方案能较好支持Twitter流式数据的高效处理和储存,使之满足系统的性能需求.     

Pivot vector method and its applications

The Gauss transformation method is modified to include simultaneously a whole vector of elements — the pivot vector — instead of a single element. This leads to a generalization of the elimination method and to development of new simplex methods. Complexity of the methods and their application to special problems of linear algebra and linear programming are discussed.Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 116–127, January–February, 1992.     

实时视频传输的自适应调节方法及其应用

实时视频是互联网上的一种重要应用.在视频传输过程中,网络状况的改变会影响视频质量.在对IP网络视频传输技术研究的基础上,提出了一种用于实时视频传输的自适应调节方法.这种方法实时监测网络资源状况,在网络资源变化时采用相应的调节手段,使所传输的视频流能够适应当前网络状况.结合一个即时视频通信系统的实现,给出了这种自适应调节方法的应用方式,并进行了实际测试,显示了自适应调节功能的运行效果.     

A pressure-correction method and its applications on an unstructured Chimera grid

In this paper, an unstructured Chimera mesh method is used to compute incompressible flow around a rotating body. To implement the pressure correction algorithm on unstructured overlapping sub-grids, a novel interpolation scheme for pressure correction is proposed. This indirect interpolation scheme can ensure a tight coupling of pressure between sub-domains. A moving-mesh finite volume approach is used to treat the rotating sub-domain and the governing equations are formulated in an inertial reference frame. Since the mesh that surrounds the rotating body undergoes only solid body rotation and the background mesh remains stationary, no mesh deformation is encountered in the computation. As a benefit from the utilization of an inertial frame, tensorial transformation for velocity is not needed. Three numerical simulations are successfully performed. They include flow over a fixed circular cylinder, flow over a rotating circular cylinder and flow over a rotating elliptic cylinder. These numerical examples demonstrate the capability of the current scheme in handling moving boundaries. The numerical results are in good agreement with experimental and computational data in literature.     

基于HBase的领域本体存储方法及其应用研究

在分析民航突发事件应急管理领域本体及其存储特点的基础上,提出了一种基于HBase的领域本体存储方法,采用将领域本体元数据与RDF实例数据分开存储的方式,给出了描述领域本体类及属性信息的元数据和RDF实例数据的存储模型,及其基于MapReduce的领域本体RDF数据并行加载过程。结合应用实现了领域本体基于HBase API的基本图模式查询,并在Hadoop环境下进行了实验与效果分析,为民航应急管理领域本体的海量数据存储提供了理论与方法支撑。     

A method for identifying Web applications

Web applications are ubiquitous in today’s businesses. The security of these applications is of utmost importance since security breaches might negatively impact good reputation, and even result in bankruptcy. There are different methods of assessing security of Web applications, mainly based on some automated method of scanning. One type of scan method feeds random data to the application and monitors its behavior. The other type uses a database with predefined vulnerabilities that are checked one by one until either a vulnerability is found, or it can be claimed that the application does not have any known vulnerabilities. The important step in latter type of scan process is the identification of the application since in this case we are narrowing number of checks and, as a consequence, the scan process is faster. This paper describes a method for Web application identification based on a black box principle. Our method is based on the invariance of certain characteristics of Web applications. We experimentally tested and confirmed the usefulness of this approach.     

Distance-based discriminant analysis method and its applications

This paper proposes a method of finding a discriminative linear transformation that enhances the data’s degree of conformance to the compactness hypothesis and its inverse. The problem formulation relies on inter-observation distances only, which is shown to improve non-parametric and non-linear classifier performance on benchmark and real-world data sets. The proposed approach is suitable for both binary and multiple-category classification problems, and can be applied as a dimensionality reduction technique. In the latter case, the number of necessary discriminative dimensions can be determined exactly. Also considered is a kernel-based extension of the proposed discriminant analysis method which overcomes the linearity assumption of the sought discriminative transformation imposed by the initial formulation. This enhancement allows the proposed method to be applied to non-linear classification problems and has an additional benefit of being able to accommodate indefinite kernels.     

基于MATLab的传感器精度校准方法

传感器为高精度仪器,由于设计原因或外界因素的干扰,会对传感器测量精度产生影响,介绍一种基于MATLab精度校准算法,以对温度敏感且本身设计存在缺陷的压力传感器为例,通过对该传感器温度t与压力p的电压数据进行实验标定、回归校准、融合计算,实现在温度因素影响下压力数据的精度校准.实验表明,该方法可明显提高测量精度.     

一个安全协议度量方法及其应用

简要说明了对安全协议进行协议度量和冗余度量的一个基于模态逻辑方法,形式化地给出了协议对安全目标满足度的度量方法定义,并讨论了相应的协议冗余分析和化简方法。给出了对安全协议的内容进行逻辑比较的准则,结合实例分析了两个协议之间的逻辑包含关系。讨论结合逆向推理的两个应用：对基于模态逻辑的协议分析中隐含假设的分析方法,协议设计和生成方法。     

CDMA信号的时频差高精度估计算法

针对多用户CDMA信号的时频域重叠特征,提出了一种新颖的时频差高精度估计方法。该方法结合扩频信号的捕获和解扩操作,以较短的信号样本和较低的计算量,仅两次时间-频率分维迭代实现了用户信号分离和时频差估计,再通过时域和频域内插进一步提高估计精度。仿真结果表明,与直接互模糊函数相关法相比,该方法能够有效提高CDMA信号时频差估计精度,降低计算量。     

解析二维非结构网格生成方法及其应用

提出弱区域指示函数描述流场形状并证明了其存在和不唯一性;利用该函数基于Delaunay方法依据流场尺度生成二维非结构网格。其中,边界引力有效解决了流场边界恢复和内嵌边界问题,弹簧振子和正三角形趋进技术有效改善网格质量。最后,弹簧振子随着弱区域指示函数的演变与监测函数的指导成功应用到自适应网格生成。     

A framework for multiple snakes and its applications

We present a framework for segmentation of multiple objects whose shapes are similar but image qualities are different. Our framework is based on the snake or active contour method, in which a new kind of energy called “group energy” is introduced. The group energy is used to handle the sharing of properties across multiple objects and also to allow contours of objects with good image qualities to be used as reference contours for remaining objects during optimization. In this framework, we also deal with rotations among similar objects by applying group energy after removing the rotation offset. Comprehensive testing has been performed on synthetic and real images, demonstrating that our framework has significantly better performance of segmentation compared to the original (individual) snake.     

一种用于专业音频传输系统的精确时钟同步方法

在专业网络音频传输系统中,由于晶振制造工艺、环境温度等因素导致主从节点音频时钟产生差异,引起系统失真率串升。而系统中以太网按照音频采样时钟的节拍来传输音频数据包。为此提出一种在物理层和MAC层的MII接口处进行音频采样时钟恢复的方案,同时设计相应的时钟调整算法进行晶振频率补偿,以提高主从节点音频时钟的同步性。在Xilinx FPGA平台上进行实际测试验证,结果表明,传输系统的失真度(包含模数和数模转换产生的失真)小于0.005%,长期运行的结果也表明了系统时钟同步的稳定性。     

分数阶动力学的分析力学方法及其应用

综述我们在分数阶动力学分析力学方法的研究进展,包括：分数阶动力学系统的分析力学表示,构造分数阶动力学模型的分析力学方法,构造分数阶动力学模型团簇的分析力学方法,三类分数阶Lie群无限小变换方法,分数阶动力学系统的对称性、对称性摄动和共形不变性的分析力学方法,分数阶动力学系统的代数结构与Poisson积分的分析力学方法,构造分数阶动力学系统积分不变量的分析力学方法,分数阶动力学系统梯度表示的分析力学方法,分数阶动力学系统稳定性的分析力学方法,分数阶微分方程的分析力学方法等,介绍了对于物理学、力学、生物学、非线性科学等领域的10多种分数阶动力学模型的应用,并指出了若干进一步研究的问题.     

一种高精度MEMS 梳齿驱动器有限元仿真方法及实验

为解决目前MEMS 梳齿电容驱动器由于边缘效应导致的理想计算模型计 算误差较大问题,利用有限单元法中的能量法,提出了一种对梳齿驱动器电容量进行精确仿 真计算的方法并以实际制作的微机械陀螺质量块上的90 对梳齿驱动器为对象,分别利用该 方法及常用的CMATRIX 仿真方法对其电容值进行了仿真计算。两种方法得到的电容量的计 算结果分别为1.5283pF 和1.5793pF。二者与利用高精度LCR 测试仪得到的结果1.5172pF 的相对误差分别为0.73%和4.09%。实验结果表明,该方法对考虑边缘效应的MEMS 梳齿 电容驱动器具有较高的计算精度。