Regional Languages on Wikipedia. Venetian Wikipedia’s user interaction over time

Given that little is known about regional language user interaction practices on Wikipedia, this study analyzed content creation process, user social interaction and exchanged content over the course of the existence of Venetian Wikipedia. Content of and user interactions over time on Venetian Wikipedia exhibit practices shared within larger Wikipedia communities and display behaviors that are pertinent to this specific community. Shared practices with\ud other Wikipedias (eg. English Wikipedia) included coordination content as a dominant category of exchanged content, user-role based structure where and most active communicators are administrators was another shared feature, as well as socialization tactics to involve users in online projects. While Venetian Wikipedia stood out for its geographically-linked users who emphasized their regional identity. User exchanges over time spilled over from online to offline domains. This analysis provides a different side of Wikipedia collaboration which is based on creation, maintenance, and negotiation of the content but also shows\ud engagement into interpersonal communication. Thus, this study exemplifies how regional language Wikipedias provide ways to their users not only to preserve their cultural heritage through the language use on regional language Wikipedia space and connect through shared contents of interest, but also, how it could serve as a community maintenance platform that unifies users with shared goals and extends communication to offline realm

Ant Colony Based Hybrid Approach for Optimal Compromise Sum-Difference Patterns Synthesis

Dealing with the synthesis of monopulse array antennas, many stochastic optimization algorithms have been used for the solution of the so-called optimal compromise problem between sum and difference patterns when sub-arrayed feed networks are considered. More recently, hybrid approaches, exploiting the convexity of the functional with respect to a sub-set of the unknowns (i.e., the sub-array excitation coefficients) have demonstrated their effectiveness. In this letter, an hybrid approach based on the Ant Colony Optimization (ACO) is proposed. At the first step, the ACO is used to define the sub-array membership of the array elements, while, at the second step, the sub-array weights are computed by solving a convex programming problem. The definitive version is available at www3.interscience.wiley.co

An Improved Excitation Matching Method based on an Ant Colony Optimization for Suboptimal-Free Clustering in Sum-Difference Compromise Synthesis

Dealing with an excitation matching method, this paper presents a global optimization strategy for the optimal clustering in sum-difference compromise linear arrays. Starting from a combinatorial formulation of the problem at hand, the proposed technique is aimed at determining the sub-array configuration expressed as the optimal path inside a directed acyclic graph structure modelling the solution space. Towards this end, an ant colony metaheuristic is used to benefit of its hill-climbing properties in dealing with the non-convexity of the sub-arraying as well as in managing graph searches. A selected set of numerical experiments are reported to assess the efficiency and current limitations of the ant-based strategy also in comparison with previous local combinatorial search methods. (c) 2009 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

Diffraction effects in length measurements by laser interferometry

High-accuracy dimensional measurements by laser interferometers require corrections because of diffraction, which makes the effective fringe-period different from the wavelength of a plane (or spherical) wave $\lambda_0$. By using a combined X-ray and optical interferometer as a tool to investigate diffraction across a laser beam, we observed wavelength variations as large as $10^{-8}\lambda_0$. We show that they originate from the wavefront evolution under paraxial propagation in the presence of wavefront- and intensity-profile perturbations.Comment: preprint, 10 pages, 6 figures, submitted to Optics Expres

Computationally-Effective Optimal Excitation Matching for the Synthesis of Large Monopulse Arrays

Antenna arrays able to generate two different patterns are widely used in tracking radar systems [1]. Optimal (in the Dolph�]Chebyshev sense) sum [2] and difference patterns [3] can be generated by using two independent feed networks. Unfortunately, such a situation generally turns out to be impracticable because of its costs, the occupied physical space, the circuit complexity, and electromagnetic interferences. Thus, starting from the optimal sum pattern a sub�]optimal solution for the difference pattern is usually synthesized by means of the sub�]array technique. The array elements are grouped in sub�]arrays properly weighted for matching the constrains of the difference beam. Finding the best elements grouping and the sub�]array weights is a complex and challenging research topic, especially when dealing with large arrays. As far as linear arrays are concerned, McNamara proposed in [4] an analytical method for determining the �gbest compromise�h difference pattern. Unfortunately, when the ratio between the elements of the array and sub�]arrays increases, such a technique exhibits several limitations mainly due to the ill�]conditioning of the problem and the computational costs due to exhaustive evaluations. A non�]negligible saving might be achieved by applying optimization algorithms (see for instance [5] and [6]) aimed at minimizing a suitable cost function. Notwithstanding, optimization�]based approaches still appear computationally expensive when dealing with large arrays because of wide dimension of solution space to be sampled. In order to properly deal with these computational issues, this contribution presents an innovative approach based on an optimal excitation matching procedure. By exploiting the relationship between independently�]optimal sum and difference patterns, the dimension of the solution space is considerably reduced and efficiently sampled by taking into account the presence of array elements more suitable to change sub�]array membership. In the following, the proposed technique is described pointing out, through a representative case, its potentialities and effectiveness in dealing with large arrays. This is the author's version of the final version available at IEEE

An innovative approach based on a tree-searching algorithm for the optimal matching of independently optimum sum and difference excitations

An innovative approach for the optimal matching of independently optimum sum and difference patterns through sub-arrayed monopulse linear arrays is presented. By exploiting the relationship between the independently optimal sum and difference excitations, the set of possible solutions is considerably reduced and the synthesis problem is recast as the search of the best solution in a non-complete binary tree. Towards this end, a fast resolution algorithm that exploits the presence of elements more suitable to charge sub-array membership is presented. The results of a set of numerical experiments are reported in order to validate the proposed approach pointing out its effectiveness also in comparison with state-of-the-art optimal matching techniques. (c) 2008 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

Synthesis of a Galile oand Wi-Max Three-Band Fractal-Eroded Patch Antenna

In this letter, the synthesis of a three-band patch antenna working in E5-L1 Galileo and Wi − Max frequency bands is described. The geometry of the antenna is defined by performing a Koch-like erosion in a classical rectangular patch structure according to a Particle Swarm strategy to optimize the values of the electrical parameters within given specifications. In order to assess the effectiveness of the antenna design, some results from the numerical synthesis procedure are described and a comparison between simulations and experimental measurements is reported. (c) 2007 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works

Analytic Design Techniques for MPT Antenna Arrays

Solar Power Satellites (SPS) represent one of the most interesting technological opportunities to provide large scale, environmentally clean and renewable energy to the Earth [1]‐[3]. A fundamental and critical component of SPSs is the Microwave Power Transmission (MPT) system, which is responsible for the delivery of the collected solar power to the ground rectenna [2]. Towards this end, the MPT array must exhibit a narrow main beam width (), a high beam efficiency (BWBE), and a low peak sidelobe level (). Moreover, reduced realization costs and weights are also necessary [3]. To reach these contrasting goals, several design techniques have been investigated including random methods [4] and hybrid deterministic‐random approaches [2][3]. On the contrary, well‐established design tools based on stochastic optimizers [5][6] are difficult to be employed, due to their high computational costs when dealing with large arrays as those of interest in SPS [3]

The Neighbourhood as Home Away from Home? Potentials and Dilemmas of Homemaking in the Public among the Somali-Swedes in Rinkeby, Stockholm

Home, as a special attachment to (and appropriation over) place, can also be cultivated in the public urban space, under certain conditions that we explore through a case study in Rinkeby, Stockholm. This article analyses various forms of homemaking in the public among the Somali-Swedes who live there. It shows how, in the case of vulnerable immigrants, a neighbourhood feels like home insofar as it facilitates a continuity with their past ways of living, sensuous connections with a shared ‘Somaliness’, reproduction of transnational ties, and protection from the sense of being ‘otherized’ that often creeps among them. However, homemaking in the public is ridden with contradictions and dilemmas, including those of self-segregation. The grassroots negotiation of a sense of home along these lines invites a novel approach into the everyday lived experience of diverse neighbourhoods in European majority-minority cities