When Does a Polynomial Over a Finite Field Permute the Elements of the Field?

We present a class of indecomposable polynomials of non prime-power degree over the finite field of two elements which are permutation polynomials on infinitely many finite extensions of the field. The associated geometric monodromy groups are the simple ...

有限构模器的扩展及其在形式化方法中的应用

规约在软件开发和验证中占有重要地位 .对于以一阶逻辑为基础的规约 ,可以利用有限模型构造技术对其执行并测试 .文中研究规约中某些特性的处理 ,包括存在量词以及二元关系的传递闭包 .对已有的一个构模工具进行扩充 ,发现了文献中的若干错误

Web应用服务器的可扩展管理模型及其实现

Web应用服务器是为事务性web应用提供一系列运行时服务的分布式系统。它既要管理多种不同类型的资源，又要集成以往成熟的网络管理协议和系统，因此，如何统一有效地管理Web应用服务器的资源、应用和服务成为实现web应用服务的一个难点。为此，本文基于JMX(Java~(TM) Management Extensions)技术，提出了一种可扩展管理模型，该模型具有较好的灵活性和开放性，可扩展能力强。同时，本文还给出了实现该模型的若干关键技术包括可扩展管理内核的实现技术、资源远程管理技术、服务可扩展管理技术。目前该模型已在我们研制的Web应用服务器 WebFrame2．O中成功实现。

Non-relativistic conformal symmetries in fluid mechanics

The symmetries of a free incompressible fluid span the Galilei group, augmented with independent dilations of space and time. When the fluid is compressible, the symmetry is enlarged to the expanded Schrodinger group, which also involves, in addition, Schrodinger expansions. While incompressible fluid dynamics can be derived as an appropriate non-relativistic limit of a conformally invariant relativistic theory, the recently discussed conformal Galilei group, obtained by contraction from the relativistic conformal group, is not a symmetry. This is explained by the subtleties of the non-relativistic limit.

Isothermal and nonisothermal crystallization of poly(aryl ether ketone ketone) with all-para phenylene linkage

Isothermal and nonisothermal crystallization behavior for PEKK(T) was studied using differential scanning calorimetry (DSC), transmission electron microscopy (TEM), and electron diffraction (ED). In the isothermal crystallization process, the Avrami parameters obtained were n = 2.33-2.69, which shows crystal growth of two-dimensional extensions consistent with our observations by TEM. The lamellar thickness increases with the crystallization temperature of PEKK(T) crystallized isothermally from the melt. However, for the nonisothermal crystallization of PEKK(T), the results from the modified Avrami analysis show two different crystallization processes. Avrami exponents n(1) = 3.61-5.30, obtained from the primary crystallization process, are much bigger than are the secondary n(2) = 2.26-3.04 and confirmed by the observation of the spherulite morphology. PEKK(T) crystallized isothermally from the melt possesses the same crystal structure (Form I) as that from nonisothermal melt crystallization. The results from TEM observation show that the spherulite radius decreases with an increasing cooling rate. (C) 2001 John Wiley & Sons, Inc.

末次冰盛期以来中国东部沙地空间分布特征及环境记录

The latest two extreme scenarios of last glacial maximum and Holocene climatic optimum marked extreme situations in China. This paper aims to reconstruct the fossil extensions and paleoclimate of deserts in eastern China during this typical period. Aeolian sequence responds the climate change by virtue of alternation of aeolian sand layer and sandy soil layer, which correspond aridity and humidity, respectively. There is a set of contrastive deposits made up of loose sand layer and overlying dark sandy soil below land surface. This developed soil and underlying deep aeolian sand respond to H.O. and late last glacial, i.e. LGM. The typical bottom sand layers of about 50 profiles of Hulun Buir Desert, Horqin Desert and Otindag Desert were dated using OSL to confirm that they did deposid in LGM. Based on the locations of these LGM sand, distrution of gobi-desert-loess and landform control, the distribution in LGM of the three deserts were reconstructed. For the block of eastern mountain, the extreme eastern boundary of Hulun Buir Desert and Otindag Desert are not just functioned by climate background. The east of Horqin Desert is plain, hence eastern boundary of this desert is maily controlled by climate. It is considered that quite a lot of aeolian sand of LGM origined from fluvial deposit by observing regional distribution of river and SEM of sand grains. The environment alternation of of LGM-H.O. is featured by extensive expanse of active dune in LGM and grassland in H.O. Combined grain-size, susceptibility, TOC, colour and SEM measurement, the OSL chronology of relatively continued profiles since LGM of the three deserts are divided into four periods: eolian sand (15-10ka)- sandy soil (10-5ka)- alternation of black sand and yellow sand- reworking of LGM sand as destroy of soil.

地幔压力下CaSiO3 Perovskite状态方程和弹性常数的第一性原理研究

In the past decade density functional theory (DFT) has made its way from a peripheral position in quantum chemistry to center. Of course the often excellent accuracy of the DFT based methods has provided the primary driving force of this development. This dissertation is devoted to the study of physical and chemical properties of planetary materials by first-principle calculation. The concerned properties include the geometry, elastic constants and anisotropy. In the first chapter, we give a systematic introduction to theoretical background and review its progress. Development of quantum chemistry promotes the establishment of DFT. Theorem of Hohenberg-Kohn is the fundament of DFT and is developed to Kohn-Sham equation, which can be used to perform real calculations. Now, new corrections and extensions, together with developed exchange-correlation, have made DFT more accurate and suitable for larger systems. In the second chapter, we focus on the calculational methods and technical aspects of DFT. Although it is important to develop methods and program, external package are still often used. At the end of this chapter, we briefly some widely used simulation package and the application of DFT. In the third chapter, we begin to focus on properties of real materials by first principles calculation. We study a kind of minerals named Ca perovskite, investigate its possible structure and anisotropy at Earth’s mental condition. By understanding and predicting geo-physically important materials properties at extreme conditions, we can get the most accurate information to interpret seismic data in the context of likely geophysical processes.

Toeplitz矩阵的循环延拓及其分析与应用

In this paper, we have presented the combined preconditioner which is derived from k =±-1~(1/2) circulant extensions of the real symmetric positive-definite Toeplitz matrices, proved it with great efficiency and stability and shown that it is easy to make error analysis and to remove the boundary effect with the combined preconditioner. This paper has also presented the methods for the direct and inverse computation of the real Toeplitz sets of equations and discussed many problems correspondingly, especially replaced the Toeplitz matrices with the combined preconditoners for analysis. The paper has also discussed the spectral analysis and boundary effect. Finally, as an application in geophysics, the paper makes some discussion about the squared root of a real matrix which comes from the Laplace algorithm.

Curved Inertia Frames: Visual Attention and Perceptual Organization Using Convexity and Symmetry

In this paper we present an approach to perceptual organization and attention based on Curved Inertia Frames (C.I.F.), a novel definition of "curved axis of inertia'' tolerant to noisy and spurious data. The definition is useful because it can find frames that correspond to large, smooth, convex, symmetric and central parts. It is novel because it is global and can detect curved axes. We discuss briefly the relation to human perception, the recognition of non-rigid objects, shape description, and extensions to finding "features", inside/outside relations, and long- smooth ridges in arbitrary surfaces.

A Theory of Networks for Appxoimation and Learning

Learning an input-output mapping from a set of examples, of the type that many neural networks have been constructed to perform, can be regarded as synthesizing an approximation of a multi-dimensional function, that is solving the problem of hypersurface reconstruction. From this point of view, this form of learning is closely related to classical approximation techniques, such as generalized splines and regularization theory. This paper considers the problems of an exact representation and, in more detail, of the approximation of linear and nolinear mappings in terms of simpler functions of fewer variables. Kolmogorov's theorem concerning the representation of functions of several variables in terms of functions of one variable turns out to be almost irrelevant in the context of networks for learning. We develop a theoretical framework for approximation based on regularization techniques that leads to a class of three-layer networks that we call Generalized Radial Basis Functions (GRBF), since they are mathematically related to the well-known Radial Basis Functions, mainly used for strict interpolation tasks. GRBF networks are not only equivalent to generalized splines, but are also closely related to pattern recognition methods such as Parzen windows and potential functions and to several neural network algorithms, such as Kanerva's associative memory, backpropagation and Kohonen's topology preserving map. They also have an interesting interpretation in terms of prototypes that are synthesized and optimally combined during the learning stage. The paper introduces several extensions and applications of the technique and discusses intriguing analogies with neurobiological data.

Resolving Ambiguity in Nonmonotonic Inheritance Hierarchies

This paper describes a theory of inheritance theories. We present an original theory of inheritance in nonmonotonic hierarchies. The structures on which this theory is based delineate a framework that subsumes most inheritance theories in the literature, providing a new foundation for inheritance. * Our path-based theory is sound and complete w.r.t. a direct model-theoretic semantics. * Both the credulous and the skeptical conclusions of this theory are polynomial-time computable. * We prove that true skeptical inheritance is not contained in the language of path-based inheritance. Because our techniques are modular w.r.t. the definition of specificity, they generalize to provide a unified framework for a broad class of inheritance theories. By describing multiple inheritance theories in the same "language" of credulous extensions, we make principled comparisons rather than the ad-hoc examination of specific examples makes up most of the comparative inheritance work.

Supporting Dynamic Languages on the Java Virtual Machine

In this note, I propose two extensions to the Java virtual machine (or VM) to allow dynamic languages such as Dylan, Scheme and Smalltalk to be efficiently implemented on the VM. These extensions do not affect the performance of pure Java programs on the machine. The first extension allows for efficient encoding of dynamic data; the second allows for efficient encoding of language-specific computational elements.

Residual Vibration Reduction in Computer Controlled Machines

Control of machines that exhibit flexibility becomes important when designers attempt to push the state of the art with faster, lighter machines. Three steps are necessary for the control of a flexible planet. First, a good model of the plant must exist. Second, a good controller must be designed. Third, inputs to the controller must be constructed using knowledge of the system dynamic response. There is a great deal of literature pertaining to modeling and control but little dealing with the shaping of system inputs. Chapter 2 examines two input shaping techniques based on frequency domain analysis. The first involves the use of the first deriviate of a gaussian exponential as a driving function template. The second, acasual filtering, involves removal of energy from the driving functions at the resonant frequencies of the system. Chapter 3 presents a linear programming technique for generating vibration-reducing driving functions for systems. Chapter 4 extends the results of the previous chapter by developing a direct solution to the new class of driving functions. A detailed analysis of the new technique is presented from five different perspectives and several extensions are presented. Chapter 5 verifies the theories of the previous two chapters with hardware experiments. Because the new technique resembles common signal filtering, chapter 6 compares the new approach to eleven standard filters. The new technique will be shown to result in less residual vibrations, have better robustness to system parameter uncertainty, and require less computation than other currently used shaping techniques.

Syntax-Based Analytic Reading of Musical Scores

As part of a larger research project in musical structure, a program has been written which "reads" scores encoded in an input language isomorphic to music notation. The program is believed to be the first of its kind. From a small number of parsing rules the program derives complex configurations, each of which is associated with a set of reference points in a numerical representation of a time-continuum. The logical structure of the program is such that all and only the defined classes of events are represented in the output. Because the basis of the program is syntactic (in the sense that parsing operations are performed on formal structures in the input string), many extensions and refinements can be made without excessive difficulty. The program can be applied to any music which can be represented in the input language. At present, however, it constitutes the first stage in the development of a set of analytic tools for the study of so-called atonal music, the revolutionary and little understood music which has exerted a decisive influence upon contemporary practice of the art. The program and the approach to automatic data-structuring may be of interest to linguists and scholars in other fields concerned with basic studies of complex structures produced by human beings.

Predicting gene function in Saccharomyces cerevisiae

Clare, A. and King R.D. (2003) Predicting gene function in Saccharomyces cerevisiae. 2nd European Conference on Computational Biology (ECCB '03). (published as a journal supplement in Bioinformatics 19: ii42-ii49)