Transfer function realization of a class of doubly-terminated two-variable lossless networks and their application in linear-phase 2-dimensional digital filter design

A method is presented for the design of a class of two-dimensional (2-D) stable digital filters satisfying prescribed magnitude and constant group delay specifications. The design method generates a 2-D digital transfer function which is a product of two transfer functions H₁(z₁,z₂) and H₂(z₁,z₂), corresponding to a recursive filter and a nonrecursive filter, respectively, Component H₁(z₁,z₂) ensures a wave-digital realization, that is, the design method guarantees the generation of a corresponding analog function H_1A(s₁,s₂) which is realizable as the transfer function of a doubly-terminated two-variable lossless network. Thus the design technique ensures that not only is a given frequency response achieved, but also the generated transfer function is realizable as a cascade of a wave-digital filter and a nonrecursive digital filter. The class of filters considered here is one in which the doubly-terminated analog network used to realize the wave digital filter is a cascade of s₁- and s₂-variable lossess two-ports with all their transmission zeros at infinity.     

Synthesis of singly-terminated ladder networks by multivariable array using homogeneous polynomials

This paper discusses a multivariable array whose elements are multivariable homogeneous polynomials which may have missing terms in any of the variables. This array permits one to obtain conditions for the realizability of a driving-point function or a transfer function as a resistively terminated low-pass ladder network. By reac- tance transformations, other forms of ladder structures can be obtained. The case of cascade-separable ladder networks is discussed in detail.     

Chain matrix decompositions,continued fractions and the optimal inhomogeneous ladder networks

Studies of two-element-kind ladder networks are well known in the classical literature, among them, the most celebrated ones are due to Cauer. Driving point immittance function synthesis by using continued fractions to obtain the series and shunt arm L-C element values is a standard and routine work. The idea of introducing a class of more general networks, the inhomogeneous ladder networks, was first developed by Lee and Brown, and subsequently the synthesis techniques of such a network were established.In this paper, new results are found such as: (1) the Iff. conditions of the existence of an inhomogeneous ladder network by a given chain matrix of the network satisfying: (a) determinant of the chain matrix is 1; (b) the zeros of A(s) and z^?1B(s) or A(s) and y^?1C(s) alternate with respect to [z(s)y(s), k] with an appropriate leading set of zeros of A(s); (c) the poles of A(s) and z^?1B(s) or A(s) and y^?1C(s) are the poles of z(s)y(s) of multiplicity of n and n?1, where n the number of sections of ladder networks; (2) the Iff. condition for the inhomogeneous ladder network to be optimal is that it be antimetrical, whereas for the extended class of inhomogeneous ladder networks it is symmetrical, where an optimal inhomogeneous ladder network is defined as the corresponding network with the minimum sum of immittance levels in the series and shunt arms; (3) algorithms of synthesis procedures were developed as the by-products of the Theorems.     

Characterization and synthesis of homogeneous two-variable reactance functions

It is shown in this paper that Homogeneous Two-variable Reactance Polyno- mials (HTRP's) can be expressed as a product of linear factors in the two-variables. Further, a Homogeneous Two-variable Reactance Function (HTRF) can be characterized in terms of the alteration property involving the coefficients of the linear factors of the HTRP in the numerator and denominator. Synthesis procedures for HTRF's are discus- sed; these realizations follow from the single variable RL- or RC-functions associated with a HTRF. Additional properties of HTRF, which will enable us to generate Two- variable Positive Real Functions and Two-variable Reactance Functions are also discussed.     

技术梯度、市场梯度与制造业产业追赶绩效

在以中国为典型的大型后发新兴经济体中,本土企业的追赶具有独特的后发优势：供给端存在连续的技术层级,需求端具备多层次的市场空间。本研究提出技术梯度、市场梯度两个构念,用以反映大型新兴经济体追赶中技术维和市场维的独特产业情境特征,并探索其对产业间追赶绩效差异的解释力。基于中国制造业26个行业2001-2007年的面板数据,检验了技术梯度、市场梯度以及它们与技术努力强度的交互作用对追赶绩效的影响。结果表明：技术梯度和市场梯度对产业追赶绩效均有着显著的促进作用;相较于技术努力强度较大或较小的情况,在技术努力强度适中的产业里,技术梯度和市场梯度对追赶绩效的影响更强。该发现对产业追赶具有重要理论和现实意义。     

Residue matrices and related properties in two-variable reactance functions

In this paper, the characterization of a two-variable reactance polynomial φ(λ,μ) is given in terms of the residue matrices of a single variable reactance matrix, Y(λ). Specificially, if Y(λ) is expressed in terms of its partial fraction as Y(λ)=λH_∞+Σ$\text{H}{}_{\mathrm{i}}\text{+jβ}{}_{\mathrm{i}}\text{λ+jω}{}_{\mathrm{i}}$+G where the residue matrices in general are p.s.d. Hermitian, then the ranks of these residue matrices are fixed in relation to the construction of φ(λ,μ) as the determinant of the two-variable reactance matrix μ1+Y(λ). Three theorems concerning these ranks—one each corresponding to the finite poles, poles at ∞ and the behaviour at λ=0 of Y(λ) are stated and proved. Several properties following from these theorems are studied. Also, implications of these theorems from a network theoretic point of view, like the minimum number of gyrators required to synthesize Y(λ) to yield the specific type of φ(λ,μ) etc., are studied. In the sequel, the concept of “generalized compact pole conditions” is introduced. Finally, these results are applied for the generation of two-variable reactance functions and matrices.     

基于无损自嵌入的图像修复方法

文中给出了一种基于无损自嵌入的图像修复方法。将JPEG压缩图像减采样，并半色调化为二值图像，使用无损数据隐藏的方法嵌入到原始图像的中低频DCT系数中。在信息提取时，原图像可得到无损地恢复；同时对提取的信息，使用反半色调化的方法可重构一幅低质量图像，当原图像中出现缺损时，可以近似地修复受损部分。     

SDRS: A new lossless dimensionality reduction for text corpora

In recent years, most content-based spam filters have been implemented using Machine Learning (ML) approaches by means of token-based representations of textual contents. After introducing multiple performance enhancements, the impact has been virtually irrelevant. Recent studies have introduced synset-based content representations as a reliable way to improve classification, as well as different forms to take advantage of semantic information to address problems, such as dimensionality reduction.These preliminary solutions present some limitations and enforce simplifications that must be gradually redefined in order to obtain significant improvements in spam content filtering. This study addresses the problem of feature reduction by introducing a new semantic-based proposal (SDRS) that avoids losing knowledge (lossless). Synset-features can be semantically grouped by taking advantage of taxonomic relations (mainly hypernyms) provided by BabelNet ontological dictionary (e.g. “Viagra” and “Cialis” can be summarized into the single features “anti-impotence drug”, “drug” or “chemical substance” depending on the generalization of 1, 2 or 3 levels).In order to decide how many levels should be used to generalize each synset of a dataset, our proposal takes advantage of Multi-Objective Evolutionary Algorithms (MOEA) and particularly, of the Non-dominated Sorting Genetic Algorithm (NSGA-II). We have compared the performance achieved by a Naïve Bayes classifier, using both token-based and synset-based dataset representations, with and without executing dimensional reductions. As a result, our lossless semantic reduction strategy was able to find optimal semantic-based feature grouping strategies for the input texts, leading to a better performance of Naïve Bayes classifiers.     

质量梯与最优专利宽度设计

通过一个质量梯模型,分别分析了孤立创新框架下和累积创新框架下双寡头厂商的研发行为和专利许可行为对子博弈精炼纳什均衡的影响,然后在此基础上分析了相关的最优专利宽度。结果表明,无论在何种创新框架下,最优专利宽度都随着市场研发效率的变化而改变。与孤立创新框架相比,累积创新框架下最优专利宽度可能较宽也可能较窄,主要取决于不同时期市场研发效率的变化,因此孤立创新框架下的专利制度可能并不适用于累积创新。     

Positive-real systems under lossless transformations: Invariants and reduced order models

In this paper, positive-real systems under lossless positive-real transformations are investigated. Let G(s) be the transfer function matrix of a continuous-time positive-real system of order n and F(s) a lossless transfer function of order n_F. We prove here that the lossless positive-real transformed system, i.e. G(F(s)), is also positive-real. Furthermore, the stochastic balanced representation of positive-real systems under lossless positive-real transformations is considered. In particular, it is proved that the positive-real characteristic values π_j of G(F(s)) are the same of G(s) each with multiplicity n_F, independently from the choice of F(s). This property is exploited in the design of reduced order models based on stochastic balancing. Finally, the proposed technique is a passivity preserving model order reduction method, since it is proven that the reduced order model of G(F(s)) is still positive-real. An error bound for truncation related to the invariants π_j is also derived.     

A theory for decoupling lossless coupled tapered lines with applications to directional couplers

A simple theory is presented for decoupling a pair of lossless coupled nonuniform transmission lines (CNUTL), with a common return and supporting TEM waves, into two lossless nonuniform transmission lines (NUTL). This theory is independent of the port terminations, symmetry conditions, etc. The method directly relates the line parameters of the lossless CNUTL's to those of the decoupled lines and vice versa; further, the matrix parameters of the CNUTL's as a four-port are explicitly expressed in terms of those of the decoupled lines as two-ports. This theory is then utilized to study the applications of CNUTL's as directional couplers.It is shown that for CNUTL's to behave as a codirectional coupler, each of the decoupled lines should be a proportional line, while for contradirectional coupler action, the two decoupled lines have to be duals of each other. The coupling response of the codirectional coupler is found to be periodic, while the phase shift between coupled and transmitted signals varies linearly with frequency. The coupling response of various contradirectional couplers with smooth transition at one of the ends, for which the decoupled lines are “basic NUTL's with hyperbolic solutions”, are studied in detail. It is shown that all these couplers have a high-pass response and that the CNUTL's with “hyperbolic cosine squared lines” as decoupled lines have the best response of all the CNUTL's considered.     

A general theory of decoupling a system of lossless coupled lines using linear transformations

This paper presents a general theory of decoupling a system of nonuniform lossless coupled lines with the aid of linear transformations. The lines have a common return and support only TEM waves. It is shown that the solution of the decoupling problem is equivalent to that of the simultaneous diagonalization of a set of real constant matrices through specially related pairs of congruent and similarity transformations. The solution of the equivalent problem yields the necessary and sufficient conditions for decoupling the system of coupled lines. A systematic procedure for decoupling is then presented. A special case is studied for which the decoupling problem becomes simpler. Finally, we have derived a set of equivalent but considerably simpler necessary and sufficient conditions for decoupling the frequently used system of a pair of lossless coupled lines.     

Realization of digital transfer functions using cascaded lattice and ladder block structures

Several techniques are available for implementing a scalar digital filter using lattice and ladder structures which are known to yield low noise realizations. Of these, the lattice and ladder structures proposed by Gray and Markel have the advantage of being internally scaled. Block implementation of a scalar digital filter offers a number of advantages. In this paper, new algorithms to realize block digital filters in the form of cascaded lattice or ladder two-pairs are proposed. Block lattice and ladder structures similar to Gray and Markel's scalar structure are obtained by using Levinson recursion. Also, normalized block lattice and ladder structures are developed.     

A lossless DNA data hiding approach for data authenticity in mobile cloud based healthcare systems

We present a lossless Deoxyribonucleic Acid (DNA) sequence hiding method that can be used for ensuring authenticity of DNA sequence in the context of Mobile Cloud based healthcare systems. Hiding data within DNA sequence results in permanent information loss in DNA sequence. Therefore, providing DNA sequence authenticity using data hiding is challenging. Moreover, existing works on DNA data hiding require a reference DNA sequence data to retrieve hidden data. Hence, current methods are not blind approaches and inappropriate for ensuring authenticity of DNA sequence in the Mobile Cloud. The proposed method hides authentication data within DNA sequence, extracts authentication data, and reconstructs the DNA sequence without any loss of information. From there, our proposed approach guarantees DNA sequence authenticity and integrity in Mobile Cloud based healthcare systems. We present a security analysis of our method to show that the method is secured. We conduct several experiments to demonstrate the performance of our proposed method.     

复杂网络理论在组织网络研究中的应用

本文通过分析复杂网络的结构特征及其内在嵌入性机理,回顾了复杂网络的基本理论现状。然后,分析得到了组织网络的非线性、多模块特征,发现了组织网络与复杂网络共同的行为模式。据此,将复杂网络引入到组织网络的研究中来,分别从组织网络的表示方法与分析手段,组织网络的互动关系和程度对其鲁棒性和适应性的影响,组织网络内在的协调机理,以及其局部互动与全局演化动力学特征之间的关系等几个方面探讨了复杂网络理论在组织网络研究中的应用前景。     

Totally homogeneous networks

In network science, the non-homogeneity of node degrees has been a concerning issue for study. Yet, with today''s modern web technologies, the traditional social communication topologies have evolved from node-central structures into online cycle-based communities, urgently requiring new network theories and tools. Switching the focus from node degrees to network cycles could reveal many interesting properties from the perspective of totally homogenous networks or sub-networks in a complex network, especially basic simplexes (cliques) such as links and triangles. Clearly, compared with node degrees, it is much more challenging to deal with network cycles. For studying the latter, a new clique vector-space framework is introduced in this paper, where the vector space with a basis consisting of links has a dimension equal to the number of links, that with a basis consisting of triangles has the dimension equal to the number of triangles and so on. These two vector spaces are related through a boundary operator, for example mapping the boundary of a triangle in one space to the sum of three links in the other space. Under the new framework, some important concepts and methodologies from algebraic topology, such as characteristic number, homology group and Betti number, will play a part in network science leading to foreseeable new research directions. As immediate applications, the paper illustrates some important characteristics affecting the collective behaviors of complex networks, some new cycle-dependent importance indexes of nodes and implications for network synchronization and brain-network analysis.     

Untangling citation networks

The pattern of citation links between articles permits a placement in a space of points representing these articles. Using the rule that articles are placed at the centroid of the articles to which they are linked, pictures can be drawn revealing key papers and their descendants. This simple rule for placing papers by their citation pattern may also be used to scale other citation-based data. The example used in this paper is the placement of overlapping groups of articles linked by shared articles.     

Random complex networks

Exactly what is meant by a ‘complex' network is not clear; however, what is clear is that it is something other than a random graph. Complex networks arise in a wide range of real social, technological and physical systems. In all cases, the most basic categorization of these graphs is their node degree distribution.Particular groups of complex networks may exhibit additional interesting features, including the so-called small-world efect or being scale-free. here are many algorithms with which one may generate networks with particular degree distributions(perhaps the most famous of which is preferential atachment). In this paper, we address what it means to randomly choose a network from the class of networks with a particular degree distribution, and in doing so we show that the networks one gets from the preferential atachment process are actually highly pathological. Certain properties(including robustness and fragility) which have been atributed to the(scale-free) degree distribution are actually more intimately related to the preferential atachment growth mechanism. We focus here on scale-free networks with power-law degree sequences—but our methods and results are perfectly generic.     

Optimal nonuniform distributed networks

Techniques developed in the Sturm—Liouville problem and its Inverse problem are well known in solving the analysis and synthesis problems of non-uniform distributed networks (or NUDN) (1)-(6), (15). However, very few practical results have been obtained from the theory, especially as regards the synthesis part of the problem. In this paper, we show that the chain matrix of an inhomogeneous ladder network (or IHLN) of N sections has undergone exactly the limit process of first-order difference equation approximation of the corresponding differential equation converges to the chain matrix of the corresponding NUDN uniformly on every compact subset of p = z(s)y(s) plane. Therefore an optimal NUDN is proven to be either symmetrical or antimetrical (7). Specifically, a class of optimal NUDN which is optimal on every subinterval of [O,L] has closed-form solutions, and is proven to be both symmetrical and antimetrical.     

Brokerage in SME networks

This study focuses on SME networks of design and high-tech companies in Southeast Netherlands. By highlighting the personal networks of members across design and high-tech industries, the study attempts to identify the main brokers in this dynamic environment. In addition, we investigate whether specific characteristics are associated with these brokers. The main contribution of the paper lies in the fact that, in contrast to most other work, it is of a quantitative nature and focuses on brokers identified in an actual network. Studying the phenomenon of brokerage provides us with clear insights into the concept of brokerage regarding SME networks in different fields. In particular we highlight how third parties contribute to the transfer and development of knowledge. Empirical results show, among others, that the most influential brokers are found in the non-profit and science sector and have a long track record in their branch.