Joint ML calibration and DOA estimation with separated arrays

This paper investigates parametric direction-of-arrival (DOA) estimation in a particular context: i) each sensor is characterized by an unknown complex gain and ii) the array consists of a collection of subarrays which are substantially separated from each other leading to a structured noise covariance matrix. We propose two iterative algorithms based on the maximum likelihood (ML) estimation method adapted to the context of joint array calibration and DOA estimation. Numerical simulations reveal that the two proposed schemes, the iterative ML (IML) and the modified iterative ML (MIML) algorithms for joint array calibration and DOA estimation, outperform the state of the art methods and the MIML algorithm reaches the Cram\'er-Rao bound for a low number of iterations

MIMO Radar Target Localization and Performance Evaluation under SIRP Clutter

Multiple-input multiple-output (MIMO) radar has become a thriving subject of research during the past decades. In the MIMO radar context, it is sometimes more accurate to model the radar clutter as a non-Gaussian process, more specifically, by using the spherically invariant random process (SIRP) model. In this paper, we focus on the estimation and performance analysis of the angular spacing between two targets for the MIMO radar under the SIRP clutter. First, we propose an iterative maximum likelihood as well as an iterative maximum a posteriori estimator, for the target's spacing parameter estimation in the SIRP clutter context. Then we derive and compare various Cram\'er-Rao-like bounds (CRLBs) for performance assessment. Finally, we address the problem of target resolvability by using the concept of angular resolution limit (ARL), and derive an analytical, closed-form expression of the ARL based on Smith's criterion, between two closely spaced targets in a MIMO radar context under SIRP clutter. For this aim we also obtain the non-matrix, closed-form expressions for each of the CRLBs. Finally, we provide numerical simulations to assess the performance of the proposed algorithms, the validity of the derived ARL expression, and to reveal the ARL's insightful properties.Comment: 34 pages, 12 figure

Bayesian Lower Bounds for Dense or Sparse (Outlier) Noise in the RMT Framework

Robust estimation is an important and timely research subject. In this paper, we investigate performance lower bounds on the mean-square-error (MSE) of any estimator for the Bayesian linear model, corrupted by a noise distributed according to an i.i.d. Student's t-distribution. This class of prior parametrized by its degree of freedom is relevant to modelize either dense or sparse (accounting for outliers) noise. Using the hierarchical Normal-Gamma representation of the Student's t-distribution, the Van Trees' Bayesian Cram\'er-Rao bound (BCRB) on the amplitude parameters is derived. Furthermore, the random matrix theory (RMT) framework is assumed, i.e., the number of measurements and the number of unknown parameters grow jointly to infinity with an asymptotic finite ratio. Using some powerful results from the RMT, closed-form expressions of the BCRB are derived and studied. Finally, we propose a framework to fairly compare two models corrupted by noises with different degrees of freedom for a fixed common target signal-to-noise ratio (SNR). In particular, we focus our effort on the comparison of the BCRBs associated with two models corrupted by a sparse noise promoting outliers and a dense (Gaussian) noise, respectively

Kohtaaminen diakonin vastaanotolla.

TIIVISTELMÄ Riutta, Vuokko. Kohtaaminen diakonin vastaanotolla. Järvenpää, syksy 2012, 47 s. 2 liitettä. Diakonia-ammattikorkeakoulu, Järvenpään yksikkö, sosionomi-diakoni (AMK) Opinnäytetyön tarkoituksena on ollut selvittää kohtaamisen merkitystä auttamis-työssä. Opinnäyteyötä on konkretisoitu diakonian asiakkaille suunnatulla laadul-lisella kyselyllä ja teemallisella haastattelulla. Julkaisussa käsitellään kohtaamisen merkitystä yleisellä tasolla eri autta-misaloilla. Julkaisussa käydään läpi diakoniatyötä yleensä ja erityisesti Korsos-sa. Korsoa ja sen väestön rakennetta selvitellään, josta selvinnee avun tarve ja tarpeellisuus. Opinnäytetyössä selvitettiin Korson seurakunnan rakennetta ja siellä tehtävää diakoniatyötä. Tieto Korson diakonian asiakkaiden kokemuksista auttamistilanteissa antaa välineitä kehittää diakonin työtä. Kohtaamisen merkitys on selvitelty asiakkaan kokemuksen kautta laadullisen kyselyn ja teemallisen haastattelun avulla. Kyselystä selvisi, että diakoniatyö on ollut erittäin tärkeää auttamistyötä, jossa taito kohdata avun tarvitsija on ollut tärkeää ja siinä on pääasiallisesti onnistuttu. Moni oli saanut avun, joka on kantanut pitkään. Miesten ja naisten kokemus diakonin luona asioinnista oli erilainen. Teemallinen haastattelu konkretisoi koh-taamisen merkityksen auttamistyössä. Vastanneet olivat enimmäkseen kokeneet, että diakonit ovat kohdanneet heidät asiallisesti ja kunnioittavasti avuntarpeessa olevan ihmisen ja he saivat paljon kiitosta tekemästään työstä. Hengellisen ulottuvuuden esillä olemista toisinaan kaivattiin ja myös esirukousta. Kaikki eivät tienneet sellaisen olevan mahdollista diakonin vastaanotolla. Avainsanat: Seurakunta, Kohtaaminen diakonin vastaanotolla, läsnäolo, avun tarve, esirukous.ABSTRACT Riutta, Vuokko. Encounter at the deacon's office. Järvenpää, Autumn 2012. 47 p., 2 Appendices. Language: Finnish. Diaconia University of Applied Sciences. Degree Programme in Social Services. Option in Diaconal Social Work, Degree: Bachelor of Social Services. The purpose of this study was to evaluate the importance of the encounter in relief work. This thesis is validated by using a qualitative survey and a themed interview that’s aimed at deacon's customers. The thesis deals with the importance of the encounter at a general level, spe-cifically in aid work. The publication goes through diaconal work in general, par-ticularly in Korso. The examining of social structures of Korso, reveals the im-portance and need for aid in Korso. In this thesis the structure and the deacon’s work in the Korso church were studied carefully. The information from the Korso diaconal customer experiences in aid giving situations provides the tools to develop the deacon's work. Significance of the encounter is analysed through the customer experience survey and a themed interview. The survey revealed that diaconal work has been very important aid work; es-pecially where the skills to face the people needing assistance has been on high importance and the needs has been met successfully. Many had received assistance, which has gone for a long time. The experience of visiting the dea-con’s office varied depending if you were a woman or a man. The themed inter-view verified the importance of this type of relief work. The respondents mostly experienced that the deacons they encountered treated them fairly and respectfully while they needed assistance. They re-ceived a lot of praise for their work. The spiritual dimension and intercession at times were needed. All were unaware of this being possible while visiting dea-con's office. Keywords: church, consultation at deacon's office, the presence, the need for assistance, intercession. SISÄLLY

On-line Tools for Solar Data Compiled at the Debrecen Observatory and their Extensions with the Greenwich Sunspot Data

The primary task of the Debrecen Heliophysical Observatory (DHO) has been the most detailed, reliable, and precise documentation of the solar photospheric activity since 1958. This long-term effort resulted in various solar catalogs based on ground-based and space-borne observations. A series of sunspot databases and on-line tools were compiled at DHO: the Debrecen Photoheliographic Data (DPD, 1974--), the dataset based on the Michelson Doppler Imager (MDI) of the Solar and Heliospheric Observatory (SOHO) called SOHO/MDI--Debrecen Data (SDD, 1996--2010), and the dataset based on the Helioseismic and Magnetic Imager (HMI) of the Solar Dynamics Observatory (SDO) called SDO/HMI--Debrecen Data (HMIDD, 2010--). User-friendly web-presentations and on-line tools were developed to visualize and search data. As a last step of compilation, the revised version of Greenwich Photoheliographic Results (GPR, 1874--1976) catalog was converted to DPD format, and a homogeneous sunspot database covering more than 140 years was created. The database of images for the GPR era was completed with the full-disc drawings of the Hungarian historical observatories \'Ogyalla and Kalocsa (1872--1919) and with the polarity drawings of Mount Wilson Observatory. We describe the main characteristics of the available data and on-line tools.Comment: 25 pages, 11 figures, accepted for publication in Solar Physic

Spontaneous polyploidisation of interspecific and intersectional Pelargonium hybrids during embryo rescue

Modern Pelargonium crispum hybrids (section Pelargonium) show low genetic and phenotypic variation due to the domestication effect. Species of the sections Cortusina, Ligularia, and Pelargonium are potential breeding partners at the diploid level (2n = 2x = 22). Five P. × crispum cultivars were used as seed parents and pollinated with one genotype of P. grandiflorum (section Pelargonium) and three genotypes of P. fulgidum (section Ligularia). In both combinations, embryo rescue was necessary. Embryos were rescued and cultured on Murashige & Skoog medium supplemented with phytohormones. After callus and adventitious shoot regeneration 15 viable interspecific hybrids were obtained from crossbreeding with P. grandiflorum and 11 intersectional hybrids from crossings with P. fulgidum, respectively. The hybrids were cultivated in the greenhouse until flowering. Their hybrid character was evident due to the intermediate morphological traits. Molecular investigations using dp-RAPD analysis confirmed this. Within the F1 population P. × crispum with P. grandiflorum three hybrids and after crossing with P. fulgidum one hybrid possessed larger flowers and fully developed anthers, respectively. Their ploidy level was confirmed as tetraploid using flow cytometry. Therefore, a spontaneous polyploidisation occurred during in vitro regeneration. The tetraploid F1 hybrids are fertile and could be used for further breeding

Résolution limite dans un contexte de localisation active de sources

National audienceDans cet article, nous étudions et analysons les performances ultimes, en termes de résolution limite, pour un problème d'estimation paramétrique dans un contexte MIMO radar. L'approche utilisée est basée sur la théorie de la détection et plus précisément en utilisant le test du rapport de vraisemblance généralisé. Cette analyse nous fournit des informations utiles quant au comportement de la résolution limite, du rapport signal à bruit minimal requis pour séparer deux sources ainsi que l'infl uence de la matrice de covariance du bruit et la connaissance préalable de la texture du bruit sur le pouvoir séparateur