990 resultados para Forward error correcting code
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Multicellular organisms rely on specialized tissues that allow for the controlled exchange of matter with their surrounding. In order to function properly, these tissues need to establish a tight connection between the individual cells to prevent uncontrolled passive diffusion across the extracellular space. In animals, these connections are called tight and adherens junctions and are a critical feature of epithelia. These connections, however, rely on direct protein-protein interaction of plasma membrane proteins of adjacent cells. Such a mechanism is not possible in plants due to the cell wall, which encases the individual cells. In order to absorb nutrients, while simultaneously preventing uncontrolled diffusion between cells, land plants have evolved the root endodermis, which is functionally equivalent to animal epithelia. Its cells are surrounded by a precisely localized and aligned, ring-like lignin deposition, called the Casparian strip, and therefore tightly connected between each other. Very little was known about the development of the endodermis and the Casparian strip until recently. In the meantime, however, we have identified a family of endodermis- specific proteins, the CASPs, which recruits extracellular proteins the specific Casparian strip membrane domain (CSD) to locally synthesize lignin in the cell wall. Yet, we hardly knew any specifics on how the CSD is initially defined and how the critically important CASPs are being recruited to it. We therefore conducted a forward genetic screen on the localization of CASPI-GFP in order to identify novel mutants, which lack a defined CSD. We identified 48 mutants, which fell into 15 different complementation groups. While some of the isolated genes had previously been identified through different approaches, nine novel genes, which had never been implicated in CSD development and maintenance, were identified. One of them, LORD OF THE RINGS 2 (.LOTR2) is described to greater detail in this work. LOTR2 encodes for EX070A1, a protein of the evolutionary conserved exocyst complex. This complex has frequently been implicated in various secretory processes across kingdoms. In Arabidopsis, it transiently defines the positioning of CASPI-GFP. We have performed a detailed analysis of the dynamics of EX070A1 and CASPI-GFP, including studies with other markers and propose a mechanism, by which the cytosolic EX070A1 transiently defines a plasma membrane domain to recruit transmembrane proteins, which then recruit extracellular enzymes for localized cell wall modification. Considering the ubiquitous expression of EX070A1, we think that this mechanism is potentially of importance not only for the endodermis and the Casparian strip but also for many other tissues, in which the cell wall becomes locally modified. In fact, many other tissues with secondary cell wall modifications contain proteins very similar to the CASPs. It will be interesting to see to which degree this mechanism is employed in other tissues. As for the endodermis, we have now identified the first gene, which is not specific to the endodermis but shows endodermis-specific dynamics. This might give us a better insight on how the plant modulates this ubiquitously present factor in a cell- or tissue-type specific manner. Considering the knowledge, mutants and tools, which are available to us for investigating the endodermis, the Casparian strip, the exocyst complex and EX070A1 might be just the right experimental system to address these questions. -- Les organismes multicellulaires dépendent des tissues spécialisé pour l'échange contrôlé entre eux et leur environnement. Pour leur bon fonctionnement, les cellules de ces tissus ont besoin d'être très étroitement assemblés afin de prévenir la diffusion non-contrôlée à travers l'espace extracellulaire. Chez les animaux, ces connexions sont appelées jonctions serrées et jonctions adhérentes. Ces jonctions dépendent des interactions directes entre les protéines des cellules voisines. Ceci n'est pas possible chez les plantes à cause de la paroi cellulaire qui recouvre chaque cellule individuellement. Pour absorber les nutriments et en même temps empêcher la diffusion non-contrôlé entre cellules, les plantes ont évolué 1'endoderme dans la racine, qui est fonctionnellement équivalent aux épithéliums des animaux. Les cellules de l'endoderme sont ceinturées par une déposition de lignine très précisément localisées comme un anneau et alignées entre les cellules, et qui, donc, connecte étroitement les cellules avoisinante: Le cadre de Caspary. Peu était connu sur le développement de l'endoderme et le cadre de Caspaiy jusqu'à il y a quelques années. Récemment, pourtant, nous avons identifié une famille de protéines spécifiques à l'endoderme, les CASPs, qui définissent le domaine membranaire du cadre de Caspaiy (CSD). Les CASPs recrutent les protéines extracellulaires nécessaire à la synthèse du cadre de Caspary vers une région limité dans la paroi cellulaire. Pourtant, on connaît très peu les processus spécifiques concernant la définition initiale du CSD et comment les CASPs, qui ont une importance cruciale, sont recrutées vers ce domaine. Par conséquent nous avons mené un crible génétique sur la localisation du CASPI- GFP, qui sert comme marqueur pour le CSD. Notre but étant d'isoler de nouveaux mutants affectés dans l'établissement du CSD. Nous avons identifié 48 mutants, en 15 groupes de complémentation. Bien que certains des gènes isolés étaient déjà impliqué dans la formation du cadre de Caspary, neuf nouveaux gènes n'ayant jamais été impliqués dans le développement ou la maintenance du CSD ont pu être identifiés. Un de ces gènes, LORD OF THE RINGS2 (LOTR2) sera décrit plus en détail dans cette étude. LOTR2 code pour EX070A1, qui est une protéine, du complexe exocyste. Ce complexe de protéines a très bien été conservé au cours de l'évolution. Il était souvent impliqué dans plusieurs processus de sécrétion dans toutes les branches de la vie. Chez Arabidopsis, EX070A1 définit la position du CSD d'une façon transitoire et recrute CASP1- GFP. Nous avons mené une analyse détaillée des dynamiques d'EX070Al et CASPI-GFP ainsi que, des études avec des autres mutants. Nous proposons un mécanisme, d'après lequel EX070A1, recruté du cytosol, définit un domaine dans la membrane plasmique pour localiser des protéines transmembranaires, ces dernières ensuite recruteront des enzymes extracellulaires pour la modification locale de la paroi cellulaire. Vu qu'EX070A1 est exprimé dans toute dans la plante, nous pensons que ce mécanisme est potentiellement important non seulement pour l'endoderme et le cadre de Caspary, mais aussi pour les autres tissus où la paroi cellulaire doit être localement modifiée. En effet, plusieurs autres tissus contiennent des protéines très similaires aux CASPs. Il serait intéressant de voir à quelle dégrée ce mécanisme est également utilisé dans ces tissues. En ce qui concerne l'endoderme, nous avons maintenant identifié le premier gène qui n'est pas exprimé spécifiquement dans l'endoderme, mais qui montre tout de même une dynamique caractéristique dans ce tissu. Il serait intéressant de voir comment la plante peut moduler ce facteur omniprésent d'une façon spécifique. Vu les connaissances, les mutants et les outils qu'on a maintenant à notre disposition, l'endoderme et son cadre de Caspary, le complexe exocyste et EX070A1 sont probablement des bons systèmes expérimentaux pour étudier ces questions. -- Identification des nouveaux facteurs pendant l'établissement du cadre de Caspary dans l'endoderme. Lothar Kalmbach, Département de Biologie Moléculaire Végétale (DBMV), Université de Lausanne. Comme tous les autres organismes multicellulaires, les plantes terrestres dépendent de tissus spécialisés pour l'échange contrôlé avec leur environnement. Ces tissus sont importants pour l'absorption des nutriments mais également pour éviter l'influx de composés toxiques. Chez les plantes, ce tissu se trouve dans la racine. C'est l'endoderme. Grâce au cadre de Caspary, qui permet une forte connexion entre les cellules au niveau de leur paroi, l'endoderme empêche les éléments toxiques d'entrer dans le système vasculaire. Depuis quelques années, nous comprenons de plus en plus la nature et la biosynthèse, ainsi que les protéines impliquées dans l'ancrage des enzymes à la membrane plasmique. Nous n'avons eu, par contre, aucune idée sur le mécanisme qui d'abord définit cet endroit dans la membrane plasmique. Nous avons mené un crible génétique sur la localisation de CASPI-GFP, une protéine, qui recrute les enzymes extracellulaires pour la synthèse du cadre de Caspary. Nous avons identifié plusieurs nouveaux gènes qui sont impliqués dans l'intégrité du cadre de Caspary. L'un de ces gènes est EX070A1, qui est un facteur ayant un rôle important lors de la sécrétion des protéines dans tous les organismes eukaryotes. Ces mutants sont gravement affectés au niveau du cadre de Caspary, mais surtout ils ne sont plus capables de localiser CASPI-GFP. Nous avons suivi la dynamique d'EX070Al et de CASP1-GFP en combinaison avec d'autres marqueurs. Nous avons pu montrer que l'accumulation d'EX070Al est spécifique pour l'endoderme et essentielle pour bien localiser CASPI-GFP et donc, le cadre de Caspary. Ces résultats nous aident à mieux comprendre le développement de l'endoderme mais peuvent potentiellement aussi être utilisés pour étudier les modifications de la paroi cellulaire dans d'autres cellules de la plante.
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PURPOSE: To assess the agreement and repeatability of horizontal white-to-white (WTW) and horizontal sulcus-to-sulcus (STS) diameter measurements and use these data in combination with available literature to correct for interdevice bias in preoperative implantable collamer lens (ICL) size selection. DESIGN: Interinstrument reliability and bias assessment study. METHODS: A total of 107 eyes from 56 patients assessed for ICL implantation at our institution were included in the study. This was a consecutive series of all patients with suitable available data. The agreement and bias between WTW (measured with the Pentacam and BioGraph devices) and STS (measured with the HiScan device) were estimated. RESULTS: The mean spherical equivalent was -8.93 ± 5.69 diopters. The BioGraph measures of WTW were wider than those taken with the Pentacam (bias = 0.26 mm, P < .01), and both horizontal WTW measures were wider than the horizontal STS measures (bias >0.91 mm, P < .01). The repeatability (Sr) of STS measured with the HiScan was 0.39 mm, which was significantly reduced (Sr = 0.15 mm) when the average of 2 measures was used. Agreement between the horizontal WTW measures and horizontal STS estimates when bias was accounted for was г = 0.54 with the Pentacam and г = 0.64 with the BioGraph. CONCLUSIONS: Large interdevice bias was observed for WTW and STS measures. STS measures demonstrated poor repeatability, but the average of repeated measures significantly improved repeatability. In order to conform to the US Food and Drug Administration's accepted guidelines for ICL sizing, clinicians should be aware of and account for the inconsistencies between devices.
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Adjusting behavior following the detection of inappropriate actions allows flexible adaptation to task demands and environmental contingencies during goal-directed behaviors. Post-error behavioral adjustments typically consist in adopting more cautious response mode, which manifests as a slowing down of response speed. Although converging evidence involves the dorsolateral prefrontal cortex (DLPFC) in post-error behavioral adjustment, whether and when the left or right DLPFC is critical for post-error slowing (PES), as well as the underlying brain mechanisms, remain highly debated. To resolve these issues, we used single-pulse transcranial magnetic stimulation in healthy human adults to disrupt the left or right DLPFC selectively at various delays within the 30-180ms interval following false alarms commission, while participants preformed a standard visual Go/NoGo task. PES significantly increased after TMS disruption of the right, but not the left DLPFC at 150ms post-FA response. We discuss these results in terms of an involvement of the right DLPFC in reducing the detrimental effects of error detection on subsequent behavioral performance, as opposed to implementing adaptative error-induced slowing down of response speed.
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Los análisis de Fourier permiten caracterizar el contorno del diente y obtener una serie de parámetros para un posterior análisis multivariante. Sin embargo, la gran complejidad que presentan algunas formas obliga a determinar el error de medición intrínseco que se produce. El objetivo de este trabajo es aplicar y validar los análisis de Fourier en el estudio de la forma dental del segundo molar inferior (M2) de cuatro especies de primates Hominoidea para explorar la variabilidad morfométrica interespecífica, así como determinar el error de medición a un nivel intra e interobservador. El contorno de la superficie oclusal del diente fue definido digitalmente y con las funciones derivadas del análisis de Fourier se realizaron Análisis Discriminantes y Test de Mantel (correlaciones de Pearson) para determinar las diferencias de forma a partir de las mediciones tomadas. Los resultados indican que el análisis de Fourier muestra la variabilidad de forma en dientes molares en especies de primates Hominoidea. Adicionalmente, los altos niveles de correlación a nivel intra (r>0,9) como interobservador (r>0,7) sugieren que la descripción morfométrica del diente a partir de métodos de Fourier realizados por diferentes observadores puede ser agrupada para posteriores análisis.
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The possibility of printing two-dimensional micropatterns of biomolecule solutions is of great interest in many fields of research in biomedicine, from cell-growth and development studies to the investigation of the mechanisms of communication between cells. Although laser-induced forward transfer (LIFT) has been extensively used to print micrometric droplets of biological solutions, the fabrication of complex patterns depends on the feasibility of the technique to print micron-sized lines of aqueous solutions. In this study we investigate such a possibility through the analysis of the influence of droplet spacing of a water and glycerol solution on the morphology of the features printed by LIFT. We prove that it is indeed possible to print long and uniform continuous lines by controlling the overlap between adjacent droplets. We show how, depending on droplet spacing, several printed morphologies are generated, and we offer, in addition, a simple explanation of the observed behavior based on the jetting dynamics characteristic of the LIFT of liquids.
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Performance standards for Positron emission tomography (PET) were developed to be able to compare systems from different generations and manufacturers. This resulted in the NEMA methodology in North America and the IEC in Europe. In practices, the NEMA NU 2- 2001 is the method of choice today. These standardized methods allow assessment of the physical performance of new commercial dedicated PET/CT tomographs. The point spread in image formation is one of the factors that blur the image. The phenomenon is often called the partial volume effect. Several methods for correcting for partial volume are under research but no real agreement exists on how to solve it. The influence of the effect varies in different clinical settings and it is likely that new methods are needed to solve this problem. Most of the clinical PET work is done in the field of oncology. The whole body PET combined with a CT is the standard investigation today in oncology. Despite the progress in PET imaging technique visualization, especially quantification of small lesions is a challenge. In addition to partial volume, the movement of the object is a significant source of error. The main causes of movement are respiratory and cardiac motions. Most of the new commercial scanners are in addition to cardiac gating, also capable of respiratory gating and this technique has been used in patients with cancer of the thoracic region and patients being studied for the planning of radiation therapy. For routine cardiac applications such as assessment of viability and perfusion only cardiac gating has been used. However, the new targets such as plaque or molecular imaging of new therapies require better control of the cardiac motion also caused by respiratory motion. To overcome these problems in cardiac work, a dual gating approach has been proposed. In this study we investigated the physical performance of a new whole body PET/CT scanner with NEMA standard, compared methods for partial volume correction in PET studies of the brain and developed and tested a new robust method for dual cardiac-respiratory gated PET with phantom, animal and human data. Results from performance measurements showed the feasibility of the new scanner design in 2D and 3D whole body studies. Partial volume was corrected, but there is no best method among those tested as the correction also depends on the radiotracer and its distribution. New methods need to be developed for proper correction. The dual gating algorithm generated is shown to handle dual-gated data, preserving quantification and clearly eliminating the majority of contraction and respiration movement
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The purpose of the METKU Project (Development of Maritime Safety Culture) is to study how the ISM Code has influenced the safety culture in the maritime industry. This literature review is written as a part of the Work Package 2 which is conducted by the University of Turku, Centre for Maritime Studies. The maritime traffic is rapidly growing in the Baltic Sea which leads to a growing risk of maritime accidents. Particularly in the Gulf of Finland, the high volume of traffic causes a high risk of maritime accidents. The growing risks give us good reasons for implementing the research project concerning maritime safety and the effectiveness of the safety measures, such as the safety management systems. In order to reduce maritime safety risks, the safety management systems should be further developed. The METKU Project has been launched to examine the improvements which can be done to the safety management systems. Human errors are considered as the most important reason for maritime accidents. The international safety management code (the ISM Code) has been established to cut down the occurrence of human errors by creating a safety-oriented organizational culture for the maritime industry. The ISM Code requires that a company should provide safe practices in ship operation and a safe working environment and establish safeguards against all identified risk. The fundamental idea of the ISM Code is that companies should continuously improve safety. The commitment of the top management is essential for implementing a safety-oriented culture in a company. The ISM Code has brought a significant contribution to the progress of maritime safety in recent years. Shipping companies and ships’ crews are more environmentally friendly and more safety-oriented than 12 years ago. This has been showed by several studies which have been analysed for this literature research. Nevertheless, the direct effect and influence of the ISM Code on maritime safety could not be isolated very well. No quantitative measurement (statistics/hard data) could be found in order to present the impacts of the ISM Code on maritime safety. In this study it has been discovered that safety culture has emerged and it is developing in the maritime industry. Even though the roots of the safety culture have been established there are still serious barriers to the breakthrough of the safety management. These barriers could be envisaged as cultural factors preventing the safety process. Even though the ISM Code has been effective over a decade, the old-established behaviour which is based on the old day’s maritime culture still occurs. In the next phase of this research project, these cultural factors shall be analysed in regard to the present safety culture of the maritime industry in Finland.
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Over the last decades, calibration techniques have been widely used to improve the accuracy of robots and machine tools since they only involve software modification instead of changing the design and manufacture of the hardware. Traditionally, there are four steps are required for a calibration, i.e. error modeling, measurement, parameter identification and compensation. The objective of this thesis is to propose a method for the kinematics analysis and error modeling of a newly developed hybrid redundant robot IWR (Intersector Welding Robot), which possesses ten degrees of freedom (DOF) where 6-DOF in parallel and additional 4-DOF in serial. In this article, the problem of kinematics modeling and error modeling of the proposed IWR robot are discussed. Based on the vector arithmetic method, the kinematics model and the sensitivity model of the end-effector subject to the structure parameters is derived and analyzed. The relations between the pose (position and orientation) accuracy and manufacturing tolerances, actuation errors, and connection errors are formulated. Computer simulation is performed to examine the validity and effectiveness of the proposed method.
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Cada cert temps hi ha assumptes d’alt interès social dins de la jurisdicció. En els últims anys, coincidint amb la crisi financera internacional, els assumptes relatius a contractes bancaris complexos, sobretot permutes financeres o swaps, han tingut una gran rellevància. En un context de crisi financera internacional, i també nacional, s'han estès el nombre de demandes dirigides contra bancs i entitats financeres. Són reclamacions en les quals se sol·licita la declaració de nul·litat dels citats contractes, principalment es basa en un error del consentiment, nul·litat que comporta la devolució de les quantitats invertides, de les rentabilitats esperades o de les penalitzacions aplicades davant la resolució anticipada d'us contractes pels clients defraudats en les seves expectatives. Les presents pàgines pretenen un estudi dels litigis sobre SWAPS, principalment dels “Interest Rate Swap”, identificar quins són els contractes bancaris complexes, quines són les normes de consentiment contractual que els regeixen. Respecte dels primers, cal destacar que l'elevat nombre de casos plantejats davant els nostres tribunals no es tradueix en una casuística tan àmplia com seria imaginable. La gran majoria versa sobre les peticions de nul·litat del contracte (total o parcial) realitzades pels clients, al moment en què l'Euribor va descendir, i que allò que molts havien contractat com un segur de cobertura enfront dels elevats tipus d'interès que havien de pagar per les seves hipoteques, veien com conforme als pactes en el contracte, havien de satisfer al seu contrapart (una entitat de crèdit) una liquidació.
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This thesis concentrates on developing a practical local approach methodology based on micro mechanical models for the analysis of ductile fracture of welded joints. Two major problems involved in the local approach, namely the dilational constitutive relation reflecting the softening behaviour of material, and the failure criterion associated with the constitutive equation, have been studied in detail. Firstly, considerable efforts were made on the numerical integration and computer implementation for the non trivial dilational Gurson Tvergaard model. Considering the weaknesses of the widely used Euler forward integration algorithms, a family of generalized mid point algorithms is proposed for the Gurson Tvergaard model. Correspondingly, based on the decomposition of stresses into hydrostatic and deviatoric parts, an explicit seven parameter expression for the consistent tangent moduli of the algorithms is presented. This explicit formula avoids any matrix inversion during numerical iteration and thus greatly facilitates the computer implementation of the algorithms and increase the efficiency of the code. The accuracy of the proposed algorithms and other conventional algorithms has been assessed in a systematic manner in order to highlight the best algorithm for this study. The accurate and efficient performance of present finite element implementation of the proposed algorithms has been demonstrated by various numerical examples. It has been found that the true mid point algorithm (a = 0.5) is the most accurate one when the deviatoric strain increment is radial to the yield surface and it is very important to use the consistent tangent moduli in the Newton iteration procedure. Secondly, an assessment of the consistency of current local failure criteria for ductile fracture, the critical void growth criterion, the constant critical void volume fraction criterion and Thomason's plastic limit load failure criterion, has been made. Significant differences in the predictions of ductility by the three criteria were found. By assuming the void grows spherically and using the void volume fraction from the Gurson Tvergaard model to calculate the current void matrix geometry, Thomason's failure criterion has been modified and a new failure criterion for the Gurson Tvergaard model is presented. Comparison with Koplik and Needleman's finite element results shows that the new failure criterion is fairly accurate indeed. A novel feature of the new failure criterion is that a mechanism for void coalescence is incorporated into the constitutive model. Hence the material failure is a natural result of the development of macroscopic plastic flow and the microscopic internal necking mechanism. By the new failure criterion, the critical void volume fraction is not a material constant and the initial void volume fraction and/or void nucleation parameters essentially control the material failure. This feature is very desirable and makes the numerical calibration of void nucleation parameters(s) possible and physically sound. Thirdly, a local approach methodology based on the above two major contributions has been built up in ABAQUS via the user material subroutine UMAT and applied to welded T joints. By using the void nucleation parameters calibrated from simple smooth and notched specimens, it was found that the fracture behaviour of the welded T joints can be well predicted using present methodology. This application has shown how the damage parameters of both base material and heat affected zone (HAZ) material can be obtained in a step by step manner and how useful and capable the local approach methodology is in the analysis of fracture behaviour and crack development as well as structural integrity assessment of practical problems where non homogeneous materials are involved. Finally, a procedure for the possible engineering application of the present methodology is suggested and discussed.
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Describes a method to code a decimated model of an isosurface on an octree representation while maintaining volume data if it is needed. The proposed technique is based on grouping the marching cubes (MC) patterns into five configurations according the topology and the number of planes of the surface that are contained in a cell. Moreover, the discrete number of planes on which the surface lays is fixed. Starting from a complete volume octree, with the isosurface codified at terminal nodes according to the new configuration, a bottom-up strategy is taken for merging cells. Such a strategy allows one to implicitly represent co-planar faces in the upper octree levels without introducing any error. At the end of this merging process, when it is required, a reconstruction strategy is applied to generate the surface contained in the octree intersected leaves. Some examples with medical data demonstrate that a reduction of up to 50% in the number of polygons can be achieved
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The directional consistency and skew-symmetry statistics have been proposed as global measurements of social reciprocity. Although both measures can be useful for quantifying social reciprocity, researchers need to know whether these estimators are biased in order to assess descriptive results properly. That is, if estimators are biased, researchers should compare actual values with expected values under the specified null hypothesis. Furthermore, standard errors are needed to enable suitable assessment of discrepancies between actual and expected values. This paper aims to derive some exact and approximate expressions in order to obtain bias and standard error values for both estimators for round-robin designs, although the results can also be extended to other reciprocal designs.
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Vehicle operations in underwater environments are often compromised by poor visibility conditions. For instance, the perception range of optical devices is heavily constrained in turbid waters, thus complicating navigation and mapping tasks in environments such as harbors, bays, or rivers. A new generation of high-definition forward-looking sonars providing acoustic imagery at high frame rates has recently emerged as a promising alternative for working under these challenging conditions. However, the characteristics of the sonar data introduce difficulties in image registration, a key step in mosaicing and motion estimation applications. In this work, we propose the use of a Fourier-based registration technique capable of handling the low resolution, noise, and artifacts associated with sonar image formation. When compared to a state-of-the art region-based technique, our approach shows superior performance in the alignment of both consecutive and nonconsecutive views as well as higher robustness in featureless environments. The method is used to compute pose constraints between sonar frames that, integrated inside a global alignment framework, enable the rendering of consistent acoustic mosaics with high detail and increased resolution. An extensive experimental section is reported showing results in relevant field applications, such as ship hull inspection and harbor mapping
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Entrevista con Manuel Villegas