基于无线技术的田间数据实时自动采集系统

准确、可靠的农田信息是实施精细农业的前提和基础。本文针对南方丘陵地区丘田小、形状不规则的特点,应用无线技术实现田间数据自动采集。系统由田间采集电路和上位机软件构成,应用点对多点通讯方式,实现多数据同时采集;数据存取为EXCEL格式,以易懂、易操作的图表方式提供给用户。为了提高采用了系统田间作业的可靠性,应用LC滤波、中值滤波和容错处理技术。试验表明系统采集精度高,可靠性好,且操作简易方便。     

Exact Learning of Formulas in Parallel

We investigate the parallel complexity of learning formulas from membership and equivalence queries. We show that many restricted classes of boolean functions cannot be efficiently learned in parallel with a polynomial number of processors.     

油膜流场可视化的实时性研究

为了建立虚拟轴承流场分析系统,提出基于粒子纹理映射的流场可视化方法．该方法能够充分利用现有的图形硬件加速器,具有绘制速度快、图像对比度高、粒子衰减过程易于控制、与流体实验现象一致等特点．文中的研究成果对于更深入地研究轴承运行过程中油膜的动态变化和传热机理具有十分重要的理论和实践意义。     

Exact algorithms for the implementation of cauchy's rule

Cauchy's little known rule for computing a lower (or upper) bound on the values of the positive roots of a polynomial equation has proven to be of great importance; namely it constitutes an indispensable and crucial part of the fastest method existing for the isolation of the real roots of an equation, a method which was recently developed by the author of this article. In this paper efficient, exact (infinite precision) algorithms, along with their computing time analysis, are presented for the implementation of this important rule.     

负实数阶广义M集内部结构的探讨

为探讨Mandelbrot集（简称M集）的内部结构,Pickover和Hooper曾分别提出了“ε正交法”和“星迹法”,文中将这两种方法进行了推广,给出了一系列负实数阶广义M集的内部结构图,研究表明：（1）负实数阶广义M集的内部结构具有分形特征。（2）负整数阶广义M集的内部结构具有对称性;而负小数阶广义M集内部结构不再具有对称性,其演化过程依赖于相角主值范围的选取。     

On Exact Learning of Unordered Tree Patterns

Tree patterns are natural candidates for representing rules and hypotheses in many tasks such as information extraction and symbolic mathematics. A tree pattern is a tree with labeled nodes where some of the leaves may be labeled with variables, whereas a tree instance has no variables. A tree pattern matches an instance if there is a consistent substitution for the variables that allows a mapping of subtrees to matching subtrees of the instance. A finite union of tree patterns is called a forest. In this paper, we study the learnability of tree patterns from queries when the subtrees are unordered. The learnability is determined by the semantics of matching as defined by the types of mappings from the pattern subtrees to the instance subtrees. We first show that unordered tree patterns and forests are not exactly learnable from equivalence and subset queries when the mapping between subtrees is one-to-one onto, regardless of the computational power of the learner. Tree and forest patterns are learnable from equivalence and membership queries for the one-to-one into mapping. Finally, we connect the problem of learning tree patterns to inductive logic programming by describing a class of tree patterns called Clausal trees that includes non-recursive single-predicate Horn clauses and show that this class is learnable from equivalence and membership queries.     

Exact controllability of a micro beam with boundary bending moment

In this paper, we show the exact controllability of a micro beam with boundary bending moment at time T > 0, which gives a confirmative answer to the open problem proposed by P. Guzmán and J. Zhu. The semi-group approach is adopted in investigation. The asymptotic spectral expression of the micro beam system is presented to verify an observability inequality for the dual system. By the duality principle, the exact controllability of the system is then established.     

网格资源实概念格模型及其算法研究

如何对资源进行组织与管理,是网格研究与应用问题中的关键课题。为了解决这个问题,出现了一系列理论方法和应用原型。首次提出了实概念格和实概念Trie树的网格资源管理策略,将形式概念分析理论和网格资源管理技术进行了有机的结合。给出了网格、资源的形式概念定义,建立了网格资源实概念格模型。利用形式概念分析方法,构造了网格资源实概念的外延Trie树和内涵Trie树,并给出了树的生成和资源与服务检索算法。实验和实例表明,这种资源组织方式是可行的和有效的。     

一个多功能路由查找引擎的设计与实现

针对网络边缘和接入层设备需处理多种网络协议和价格敏感的特点,文中介绍了一种能支持精确匹配和最长前缀匹配的多功能查找引擎。此引擎以五级环行多功能流水线为核心,通过SRAM接口与主机交互,采用ZBTSRAM作为路由表存储器。文中着重介绍了引擎的硬件结构、软件系统和软硬件联合验证方法。性能评测表明,基于FPGA的实现主频可达到50MHz,性能可以满足1Gbps￣2Gbps的接入和边缘层设备要求。     

On The Exact Controllability of Impulsive Fractional Semilinear Functional Differential Inclusions

In this paper, we deal with the exact controllability for impulsive fractional semilinear functional differential inclusions in Hilbert spaces. Under suitable assumptions, the exact controllability of the control systems are formulated and proved. The main tools in our study rely on the fixed point theorem for multivalued maps due to Dhage associated with evolution systems.     

The Exact Maximum Likelihood-Based Test for Fractional Cointegration: Critical Values,Power and Size

The exact maximum likelihood (EML) procedure can be used as a residual-based test of the hypothesis of no cointegration against the alternative of fractional cointegration. Since the corresponding asymptotic properties have not yet been established, this paper provides simulated critical values, power and size relating to the EML-based test for fractional cointegration. Monte Carlo simulations indicate that the simulated density of the EML-based test is shifted to the left compared to the standard normal distribution and exhibits a strong excess of kurtosis in the absence of autoregressive components in the regression residuals. The power and size comparison indicates that the EML-based test is more powerful than other fractional cointegration tests (Lo, Lobato-Robinson and Geweke and Porter-Hudak) in small and medium sample sizes. Moreover, by simulating integrated time series with AR(1), and respectively MA(1), disturbances, it is shown that, whatever the sample size, the EML-based test exhibits the lowest size distortions for positive AR(1) and negative MA(1) coefficients, respectively.JEL classifications: C15; C22     

精确线性化的永磁同步电机变结构混沌反控制

以永磁同步电机的仿射非线眭数学模型为例,提出了基于非线陛跟踪的混沌反控制方法。采用微分几何理论实现了永磁同步电机的精确线性化,并应用滑模变结构控制理论设计混沌反控制器。仿真结果表明,该控制方法能有效的实现永磁同步电机的混沌反控制。     

一类隐含离散时间奇异非线性系统的精确线性化

讨论隐含离散时间奇异非线性系统的精确线性化问题。首先利用重排算法将系统转化为正常形式，然后给出并证明了系统通过坐标变换线性化的充分条件。     

GIS技术在房地产管理中的应用

通过介绍GIS的概念及房地产管理的空间特征,分析了GIS在房地产管理中的优势及可行性,指出了在房产管理数据库的基础上实现房地产数字化管理的实现途径。     

一种新的实时事务并发控制方法

本文提出一种新的实时事务并发控制方法，并对其性能进行了模拟评测；与锁式协议，乐观协议，基于时间戳的协议相比，它可以获得更新的并发度，与诸如ε－可串行比、△－可串行化等一致性的放松可串行化并发控制技术相比，它维护强一致性，保证严格可串行化。     

Linux强实时方案及测试

Linux作为UNIX类操作系统,其分时设计特性使其实时性能可满足普通实时的需求,而随着控制领域应用系统的发展,对具有传统操作系统功能的强实时操作系统需求日益迫切;通过强实时扩展核的方式实现Linux的强实时特性,使Linux可以在一定范围内满足控制领域应用对强实时应用的需求。     

Relatively Computable Functions of Real Variables

In this paper we introduce the notion of relative computability for continuous real valued functions. It combines the notion of relative recursiveness for number theoretic functions with the theory of computability for continuous real valued functions. Most of the space is devoted to investigating the degrees of unsolvability of those mathematical operations which lead from the computable to the noncomputable. The paper concludes with Theorem 5, which asserts that the derivatives of computable C ¹ functions on compact intervals are at most semi-computable. Received May 15, 2000     

Bounding the Vapnik-Chervonenkis Dimension of Concept Classes Parameterized by Real Numbers

The Vapnik-Chervonenkis (V-C) dimension is an important combinatorial tool in the analysis of learning problems in the PAC framework. For polynomial learnability, we seek upper bounds on the V-C dimension that are polynomial in the syntactic complexity of concepts. Such upper bounds are automatic for discrete concept classes, but hitherto little has been known about what general conditions guarantee polynomial bounds on V-C dimension for classes in which concepts and examples are represented by tuples of real numbers. In this paper, we show that for two general kinds of concept class the V-C dimension is polynomially bounded in the number of real numbers used to define a problem instance. One is classes where the criterion for membership of an instance in a concept can be expressed as a formula (in the first-order theory of the reals) with fixed quantification depth and exponentially-bounded length, whose atomic predicates are polynomial inequalities of exponentially-bounded degree, The other is classes where containment of an instance in a concept is testable in polynomial time, assuming we may compute standard arithmetic operations on reals exactly in constant time.Our results show that in the continuous case, as in the discrete, the real barrier to efficient learning in the Occam sense is complexity-theoretic and not information-theoretic. We present examples to show how these results apply to concept classes defined by geometrical figures and neural nets, and derive polynomial bounds on the V-C dimension for these classes.