On the estimation of transfer functions,regularizations and Gaussian processes—Revisited

Intrigued by some recent results on impulse response estimation by kernel and nonparametric techniques, we revisit the old problem of transfer function estimation from input–output measurements. We formulate a classical regularization approach, focused on finite impulse response (FIR) models, and find that regularization is necessary to cope with the high variance problem. This basic, regularized least squares approach is then a focal point for interpreting other techniques, like Bayesian inference and Gaussian process regression. The main issue is how to determine a suitable regularization matrix (Bayesian prior or kernel). Several regularization matrices are provided and numerically evaluated on a data bank of test systems and data sets. Our findings based on the data bank are as follows. The classical regularization approach with carefully chosen regularization matrices shows slightly better accuracy and clearly better robustness in estimating the impulse response than the standard approach–the prediction error method/maximum likelihood (PEM/ML) approach. If the goal is to estimate a model of given order as well as possible, a low order model is often better estimated by the PEM/ML approach, and a higher order model is often better estimated by model reduction on a high order regularized FIR model estimated with careful regularization. Moreover, an optimal regularization matrix that minimizes the mean square error matrix is derived and studied. The importance of this result lies in that it gives the theoretical upper bound on the accuracy that can be achieved for this classical regularization approach.     

On Model, Memory Management and Interface in EDBMS/3

Engineering application domains need database management systems to supply them with a good means of modeling,a high data access efficiency and a language interface with strong functionality.This paper presents a semantic hypergraph model based on relations,in order to express many-to-many relations among objects belonging to different semantic classes in engineering applications.A management mechanism expressed by the model and the basic data of engineering databases are managed in main memory.Especially,different objects are linked by different kinds of semantics defined by users,therefore the table swap,the record swap and some unnecessary examinations ar reduced and the access efficiency of the engineering data is increased.C language interface that includes some generic and special functionality is proposed for closer connection with application programs.     

On Factorizing the Symbolic U-resultant — Application of the ddet operator —

This paper presents a new, practical, efficient algorithm for factorizing the U-resultant of a system of algebraic equations with finitely many solutions. Given a matrix whose determinant is the U-resultant, our algorithm obtains the true linear factors with exact multiplicities, directly from the matrix without expanding the multivariate determinant. The main focuses are laid upon the use of a new operator, which enables us to treat only matrices of univariate polynomial elements, and also upon the exact treatment of multiplicities, which is made possible by the symbolic representation of solutions in simple algebraic extensions of Q. The algorithm is probabilistic in the sense that there exists no deterministic method to give an appropriate parameterization. The efficiency of our algorithm will be demonstrated with some empirical problems.     

On the Numerical Controllability of the Two-Dimensional Heat,Stokes and Navier–Stokes Equations

The aim of this work is to present some strategies to solve numerically controllability problems for the two-dimensional heat equation, the Stokes equations and the Navier–Stokes equations with Dirichlet boundary conditions. The main idea is to adapt the Fursikov–Imanuvilov formulation, see Fursikov and Imanuvilov (Controllability of Evolutions Equations, Lectures Notes Series, vol 34, Seoul National University, 1996); this approach has been followed recently for the one-dimensional heat equation by the first two authors. More precisely, we minimize over the class of admissible null controls a functional that involves weighted integrals of the state and the control, with weights that blow up near the final time. The associated optimality conditions can be viewed as a differential system in the three variables \(x_1\), \(x_2\) and t that is second-order in time and fourth-order in space, completed with appropriate boundary conditions. We present several mixed formulations of the problems and, then, associated mixed finite element Lagrangian approximations that are relatively easy to handle. Finally, we exhibit some numerical experiments.     

0/1背包问题

本文对“0/1背包问题”采用贪婪算法、动态规划、回溯法、分枝限界四种不同方法进行求解和算法分析,并通过各种算法的实现,研究了0/1背包问题的实质。     

On the variation and specialisation of workload—A case study of the Gnome ecosystem community

Most empirical studies of open source software repositories focus on the analysis of isolated projects, or restrict themselves to the study of the relationships between technical artifacts. In contrast, we have carried out a case study that focuses on the actual contributors to software ecosystems, being collections of software projects that are maintained by the same community. To this aim, we defined a new series of workload and involvement metrics, as well as a novel approach— $\widetilde{\mathbf{T}}$ -graphs—for reporting the results of comparing multiple distributions. We used these techniques to statistically study how workload and involvement of ecosystem contributors varies across projects and across activity types, and we explored to which extent projects and contributors specialise in particular activity types. Using Gnome as a case study we observed that, next to coding, the activities of localization, development documentation and building are prevalent throughout the ecosystem. We also observed notable differences between frequent and occasional contributors in terms of the activity types they are involved in and the number of projects they contribute to. Occasional contributors and contributors that are involved in many different projects tend to be more involved in the localization activity, while frequent contributors tend to be more involved in the coding activity in a limited number of projects.     

0/1背包问题

本文对“0／1背包问题”采用贪婪算法、动态规划、回溯法、分枝限界四种不同方法进行求解和算法分析．并通过各种算法的实现．研究了0／1背包问题的实质。     

0/1背包问题

本文对0/1背包问题采用贪婪算法、动态规划、回溯法、分枝限界四种不同方法进行求解和算法分析,并通过各种算法的实现,研究了0/1背包问题的实质。     

On the Relationship Between TMS and Logic Programs

The relationship between TMS and general logic programs is an important issue in non-monotonic logic programming.In this paper,we prove that,after we translate the TMS theory into a general logic program,the TMS‘s well-founded assignment (or extension) is equivalent to the corresponding general logic program‘s stable model.It means that TMS can be completely integrated into a non-monotonic logic programming environment.     

On the structure of multivariate concentration — some relationships among the concentration surface and two variate mean difference and regressions

First, concentration surface L(x, y) and Gini's coefficient G_xy with respect to two variates x and y are defined and discussed. Mean difference Δ_xy and mean deviation δ_xy of x and y are also defined in connection with L(x,y) and G_xy. Some other statistical measures working like correlation coefficient and regression coefficient are newly introduced based on the geometrical properties of the concentration surface and are discussed in comparison with moment measures corresponding to them.Non-linear regression is also discussed based on certain representative income distributions.The close relations between Gini's coefficient G_xy and the regression residuals are pointed out in the case of both linear and non-linear regressions.Finally, elasticity analysis is tried on the family budget data of Japan in 1981.     

EMBASE Remains EMBASE—On Every Host? A Comparative Analysis of EMBASE on the Hosts DATA-STAR,DIALOG, DIMDI,and STN

Differing results of the same search request processed on different hosts led the authors to investigate this issue more thoroughly. Two authors, two journal titles, two drug names, and two topics of a general medical nature were retrieved under identical circumstances and conditions on the hosts DATA-STAR¹, DIALOG1, DIMDI, and STN. Comparing the figures revealed that none of the nine search requests produced an identical result onallhosts. Some of the search results differed only slightly, while the searches in the basic index produced considerable discrepancies.     

On the Communication Structures of Hyper-Ring and Hypercube Multicomputers

The well-known torus an its variants,which we call hyper-rings,as well as hypercube architectures are further studied and evaluated as interconnecion networks for multicomputers,Comparisons are made among hyper-rings and between hyper-ring and hypercube networks under different communication patterns.It is concluded that although it is believed that a hypercube is generally superior to hyper-rings in performance,this is not always the case,paricu larly for locally constrained applications,where communications occur mostly among neighboring nodes.     

浅析0/1背包问题

0/1背包问题是个典型问题,其解法有很多,如回溯法、分枝限界法、动态规划法、递归策略等.本文以动态规划的方法(向前处理法)为例,详细解析了本问题,首先根据公式对问题一步步进行了推导,然后用图解法再次进行了研究,比较简单的解决了问题,并采用不同于资料上的方法,通过实例对其的可行性进行了验证,达到了预期的效果.     

浅析0/1背包问题

0/1背包问题是个典型问题,其解法有很多,如回溯法、分枝限界法、动态规划法、递归策略等。本文以动态规划的方法(向前处理法)为例,详细解析了本问题,首先根据公式对问题一步步进行了推导,然后用图解法再次进行了研究,比较简单的解决了问题,并采用不同于资料上的方法,通过实例对其的可行性进行了验证,达到了预期的效果。     

Fast,effective heuristics for the 0–1 multi-dimensional knapsack problem

The objective of the multi-dimensional knapsack problem (MKP) is to find a subset of items with maximum value that satisfies a number of knapsack constraints. Solution methods for MKP, both heuristic and exact, have been researched for several decades. This paper introduces several fast and effective heuristics for MKP that are based on solving the LP relaxation of the problem. Improving procedures are proposed to strengthen the results of these heuristics. Additionally, the heuristics are run with appropriate deterministic or randomly generated constraints imposed on the linear relaxation that allow generating a number of good solutions. All algorithms are tested experimentally on a widely used set of benchmark problem instances to show that they compare favourably with the best-performing heuristics available in the literature.     

On the Euler sequence spaces which include the spaces ?p and ?∞ I

In the present paper, we introduce the Euler sequence space consisting of all sequences whose Euler transforms of order r are in the space ?_p of non-absolute type which is the BK-space including the space ?_p and prove that the spaces and ?_p are linearly isomorphic for 1 ? p ? ∞. Furthermore, we give some inclusion relations concerning the space . Finally, we determine the α-, β- and γ-duals of the space for 1 ? p ? ∞ and construct the basis for the space , where 1 ? p < ∞.     

On WLCDs and the Complexity of Word-Level Decision Diagrams—A Lower Bound for Division

Several types of Decision Diagrams (DDs) have been proposed for the verification of Integrated Circuits. Recently, word-level DDs like BMDs, *BMDs, HDDs, K*BMDs and *PHDDs have been attracting more and more interest, e.g., by using *BMDs and *PHDDs it was for the first time possible to formally verify integer multipliers and floating point multipliers of significant bitlengths, respectively.On the other hand, it has been unknown, whether division, the operation inverse to multiplication, can be efficiently represented by some type of word-level DDs. In this paper we show that the representational power of any word-level DD is too weak to efficiently represent integer division. Thus, neither a clever choice of the variable ordering, the decomposition type or the edge weights, can lead to a polynomial DD size for division.For the proof we introduce Word-Level Linear Combination Diagrams (WLCDs), a DD, which may be viewed as a generic word-level DD. We derive an exponential lower bound on the WLCD representation size for integer dividers and show how this bound transfers to all other word-level DDs.     

On the algebraic specification of infinite objects — ordered and continuous models of algebraic types

Summary The concept of algebraic types is adapted to allow axiomatic characterizations of ordered and continuous algebras; infinite objects are then limit points in the carriers of certain continuous algebras. We mainly study implicative types, i.e., types the axioms of which are conditional inequations describing partial orders. The isomorphism classes of termgenerated ordered models of an implicative type are shown to form a complete lattice under the homomorphism ordering; this includes the wellknown initiality results for equational and conditional types as special cases. For types whose axioms specify strictness of the operations, the initial models are shown to correspond to flat domains.As a special kind of continuous algebras we consider inductively generated algebras, viz. the ideal completions of term-generated ordered algebras. For an inequational type, i.e., an implicative type where all axiom premises are empty, the completion of models always yields models again, whereas for implicative types this holds only in restricted cases. One such case is provided by hierarchic types which are complete and consistent relative to their primitive parts, and which satisfy certain conditions about limit points.Examples of algebras that can be specified by such types include those of finite and infinite streams, of sets of atoms under the Egli-Milner ordering, Milner's synchronisation trees, and that of a simple functional language over the natural numbers.This research was carried out within the Sonderforschungsbereich 49 Programmiertechnik, Munich, Federal Republic of Germany     

On Division in Extreme and Mean Ratio and its Connection to a Particular Re-Expression of the Golden Quadratic Equation x 2 − x − 1 = 0

The golden quadratic x² − x − 1 = 0, when re-expressed as (x)(1) = 1/(x − 1), x = 1.618, can be interpreted as the algebraic expression of division in extreme and mean ratio (DEMR) of a line of length x = 1.618 into a longer section of length 1 and a smaller of length (x − 1). It can, however, also be interpreted as the formulation of the area of a golden rectangle of sides x = 1.618 and 1, and as the system of equations constituted by y =  x, and y = 1/(x − 1). Based on the well-known connection existing between the first two of these interpretations, the authors address the problem of finding out the thread connecting the golden rectangle with the system of equations referred to above. The results obtained indicate first that this system, like the golden rectangle, also carries in its geometry the essential traits of DEMR; and, second, that it implicitly subsumes the simpler rectangular geometry of its alternative interpretation. The process of developing these connections brought forward a heretofore apparently unreported golden trapezoid of sides Φ, 1, ϕ and .     

On the privacy offered by (k, δ)-anonymity

The widespread deployment of technologies with tracking capabilities, like GPS, GSM, RFID and on-line social networks, allows mass collection of spatio-temporal data about their users. As a consequence, several methods aimed at anonymizing spatio-temporal data before their publication have been proposed in recent years. Such methods are based on a number of underlying privacy models. Among these models, (k,δ)-anonymity$(k,\delta )\mathrm{-}\mathrm{anonymity}$ claims to extend the widely used k  -anonymity concept by exploiting the spatial uncertainty δ≥0$\delta \ge 0$ in the trajectory recording process. In this paper, we prove that, for any δ>0$\delta >0$ (that is, whenever there is actual uncertainty), (k,δ)-anonymity$(k,\delta )\mathrm{-}\mathrm{anonymity}$ does not offer trajectory k-anonymity, that is, it does not hide an original trajectory in a set of k   indistinguishable anonymized trajectories. Hence, the methods based on (k,δ)-anonymity$(k,\delta )\mathrm{-}\mathrm{anonymity}$, like Never Walk Alone (NWA) and Wait For Me (W4M) can offer trajectory k  -anonymity only when δ=0$\delta =0$ (no uncertainty). Thus, the idea of exploiting the recording uncertainty δ$\delta$ to achieve trajectory k  -anonymity with information loss inversely proportional to δ$\delta$ turns out to be flawed.