How distant are the Portuguese regions? A multidimensional scaling application

Despite being a small country, Portugal is characterised by significant regional disparities which are evident from the analysis of numerous indicators such as the level of income or the unemployment rate. These regional disparities acquire characteristics that, in a sense, do not respect the traditional pattern as the one expected when assuming that standards of living decrease with the distance of each region to the region where economic prosperity is higher. Plainly, this means that, besides the geographical map, it is possible to construct an alternative map of the regions of Portugal which, by its characteristics, is certainly much more interesting from the regional economics point of view. This can be done through the use of multidimensional scaling as it allows representing graphically the regions in a way to reproduce as close as possible the economic distances of the regions as measured by traditional indicators. The analysis of the multidimensional scaling output makes it then possible, on the one hand, to verify how geographical distances are related with economic ones and, on the other hand, to verify if the Portuguese regional economic policies have, indeed, contributed to a diminishment of those regional disparities. KEY-WORDS: Distance, Multidimensional Scaling, Portugal, Regional Disparities JEL CLASSIFICATION: C14, R12, R15

Distributed on-line multidimensional scaling for self-localization in wireless sensor networks

The present work considers the localization problem in wireless sensor networks formed by fixed nodes. Each node seeks to estimate its own position based on noisy measurements of the relative distance to other nodes. In a centralized batch mode, positions can be retrieved (up to a rigid transformation) by applying Principal Component Analysis (PCA) on a so-called similarity matrix built from the relative distances. In this paper, we propose a distributed on-line algorithm allowing each node to estimate its own position based on limited exchange of information in the network. Our framework encompasses the case of sporadic measurements and random link failures. We prove the consistency of our algorithm in the case of fixed sensors. Finally, we provide numerical and experimental results from both simulated and real data. Simulations issued to real data are conducted on a wireless sensor network testbed.Comment: 32 pages, 5 figures, 1 tabl

Optimized hybrid localisation with cooperation in wireless sensor networks

In this study, the authors introduce a novel hybrid cooperative localisation scheme when both distance and angle measurements are available. Two linear least squares (LLS) hybrid cooperative schemes based on angle of arrival–time of arrival (AoA–ToA) and AoA–received signal strength (AoA–RSS) signals are proposed. The proposed algorithms are modified to accommodate cooperative localisation in resource constrained networks where only distance measurements are available between target sensors (TSs) while both distance and angle measurements are available between reference sensors and TSs. Furthermore, an optimised version of the LLS estimator is proposed to further enhance the localisation performance. Moreover, localisation of sensor nodes in networks with limited connectivity (partially connected networks) is also investigated. Finally, computational complexity analysis of the proposed algorithms is presented. Through simulation, the superior performance of the proposed algorithms over its non-cooperative counterpart and the hybrid signal based iterative non-linear least squares algorithms is demonstrated

An Algorithm for the Continuous Morlet Wavelet Transform

This article consists of a brief discussion of the energy density over time or frequency that is obtained with the wavelet transform. Also an efficient algorithm is suggested to calculate the continuous transform with the Morlet wavelet. The energy values of the Wavelet transform are compared with the power spectrum of the Fourier transform. Useful definitions for power spectra are given. The focus of the work is on simple measures to evaluate the transform with the Morlet wavelet in an efficient way. The use of the transform and the defined values is shown in some examples.Comment: 15 pages, 4 figures, revised for MSS

Motion magnification in coronal seismology

We introduce a new method for the investigation of low-amplitude transverse oscillations of solar plasma non-uniformities, such as coronal loops, individual strands in coronal arcades, jets, prominence fibrils, polar plumes, and other contrast features, observed with imaging instruments. The method is based on the two-dimensional dual tree complex wavelet transform (DT$\mathbb{C}$WT). It allows us to magnify transverse, in the plane-of-the-sky, quasi-periodic motions of contrast features in image sequences. The tests performed on the artificial data cubes imitating exponentially decaying, multi-periodic and frequency-modulated kink oscillations of coronal loops showed the effectiveness, reliability and robustness of this technique. The algorithm was found to give linear scaling of the magnified amplitudes with the original amplitudes provided they are sufficiently small. Also, the magnification is independent of the oscillation period in a broad range of the periods. The application of this technique to SDO/AIA EUV data cubes of a non-flaring active region allowed for the improved detection of low-amplitude decay-less oscillations in the majority of loops.Comment: Accepted for publication in Solar Physic

CES-516 Three-Dimensional Localisation using Cricket System

The Cricket system is a kind of wireless sensor networks used for indoor localisa- tion, which is developed by MIT and Crossbow. It can be deployed to compute the location information for various devices, such as computer and cell phone. This report firstly describes the initialisation of Cricket and the additional resources. Then, a three- dimensional localisation algorithm is designed based on the optimisation method. Its performance is analysed in simulation and compared with the two existing localisation algorithms. The simulation results demonstrate its high localisation accuracy. Moreover, a new program, namely CricketMFC, is developed to initialise the localisation system by deploying Java, Matlab and Microsoft Foundation Classes (MFC). It also can be used to compute the three-dimensional position and display the results in three-dimensional coordinates in real time. The real experiment clearly verifies that the designed algorithm provides very good localisation results and the CricketMFC is an efficient localisation system

Performance Appraisal Research: A Critical Review of Work on “The Social Context and Politics of Appraisal”

This paper reviews existing literatures on the analysis of performance appraisal (PA) paying special attention to those which try to take into account the “social context” of appraisal systems and processes. The special place of political action within these processes is underlined and the different levels at which politics need to be considered in research are outlined. Research on politics is considered and shown to lack an adequate consideration of the social relations involved in the reciprocal interactions between PA tools and processes and users interpretation and manipulation of them.Performance appraisal; Social context; Politics