Concurrent mapping and localization using sidescan sonar   总被引：1，自引：0，他引：1  

Tena Ruiz  I. de Raucourt  S. Petillot  Y. Lane  D.M. 《Oceanic Engineering, IEEE Journal of》2004,29(2):442-456

This paper describes and evaluates a concurrent mapping and localization (CML) algorithm suitable for localizing an autonomous underwater vehicle. The proposed CML algorithm uses a sidescan sonar to sense the environment. The returns from the sonar are used to detect landmarks in the vehicle's vicinity. These landmarks are used, in conjunction with a vehicle model, by the CML algorithm to concurrently build an absolute map of the environment and to localize the vehicle in absolute coordinates. As the vehicle moves forward, the areas covered by a forward-look sonar overlap, whereas little or no overlap occurs when using sidescan sonar. It has been demonstrated that numerous reobservations by a forward-look sonar of the landmarks can be used to perform CML. Multipass missions, such as sets of parallel and regularly spaced linear tracks, allow a few reobservations of each landmark with sidescan sonar. An evaluation of the CML algorithm using sidescan sonar is made on this type of trajectory. The estimated trajectory provided by the CML algorithm shows significant jerks in the positions and heading brought about by the corrections that occur when a landmark is reobserved. Thus, this trajectory is not useful to mosaic the sea bed. This paper proposes the implementation of an optimal smoother on the CML solution. A forward stochastic map is used in conjunction with a backward Rauch-Tung-Striebel filter to provide the smoothed trajectory. This paper presents simulation and real results and shows that the smoothed CML solution helps to produce a more accurate navigation solution and a smooth navigation trajectory. This paper also shows that the qualitative value of the mosaics produced using CML is far superior to those that do not use it.  相似文献   

General patterns of circulation, sediment fluxes and ecology of the Palamós (La Fonera) submarine canyon, northwestern Mediterranean     

Albert Palanques  Emilio García-Ladona  Dami Gomis  Jacobo Martín  Marta Marcos  Ananda Pascual  Pere Puig  Josep-Maria Gili  Mikhail Emelianov  Sebasti Monserrat  Jorge Guilln  Joaquín Tintor  Mariona Segura  Antoni Jordi  Simn Ruiz  Gotzon Basterretxea  Jordi Font  Dolors Blasco  Francesc Pags 《Progress in Oceanography》2005,66(2-4):89

Currents, particle fluxes and ecology were studied in the Palamós submarine canyon (also known as the Fonera canyon), located in the northwestern Mediterranean. Seven mooring arrays equipped with current meters and sediment traps were deployed along the main canyon axis, on the canyon walls and on the adjacent slope. Additionally, local and regional hydrographic cruises were carried out. Current data showed that mean near surface and mid-depth currents were oriented along the mean flow direction (NE–SW), although at 400 and 1200 m depth within the canyon current reversals were significant, indicating a more closed circulation inside the canyon. Mean near-bottom currents were constrained by the local bathymetry, especially at the canyon head. The most significant frequency at all levels was the inertial frequency. A second frequency of about three days, attributed to a topographic wave, was observed at all depths, suggesting that this wave was probably not trapped near the bottom. The current field observed during the most complete survey revealed a meandering pattern with cyclonic vorticity just upstream from and within the canyon. The associated vertical velocity ranged between 10 and 20 m/day and was constrained to the upper 300 m. This latter feature, together with other computations, suggests that during this survey the meander was not induced by the canyon but by some kind of instability of the mean flow.In the canyon, suspended sediment concentration, downward particle fluxes, chlorophyll and particulate C and N were significantly higher up-canyon from about 1200 m depth than offshore, defining, along with the different hydrodynamics, two canyon domains: one from the canyon head to about 1200 m depth more affected by the canyon confinement and the other deeper than 1200 m depth more controlled by the mean flow and the shelf-slope front. The higher near-bottom downward total mass fluxes were recorded in the canyon axis at 1200 m depth along with sharp turbidity increases and are related to sediment gravity flows. During the deployment period, the increase in downward particle fluxes occurred by mid-November, when a severe storm took place. On the canyon walls at 1200 m depth, suspended sediment concentrations, downward particle fluxes, chlorophyll and particulate C and N were higher on the southern wall than on the northern wall inversely to the current’s energy. This could be caused by an upward water supply on the southern canyon wall and/or the mean flow interacting with the canyon bathymetry. In the swimmers collected by the sediment traps, the dominant species was an elasipod holothurian, which has not been recorded in other canyons or elsewhere in the Mediterranean, indicating particular speciation.  相似文献   

Dumpton syndrome reduces the tributyltin (TBT) sterilising effect on Nucella lapillus (L.) by limiting the development of the imposed vas deferens     

Quintela M  Barreiro R  Ruiz JM 《Marine environmental research》2002,54(3-5):657-660

TBT induces imposex and sterilisation in female Nucella lapillus. Interestingly, there are populations where individuals (both males and imposexed females) may suffer from a genetic aberration [Dumpton Syndrome (DS)] which results in the development of no penis (i.e. aphally). This anomaly confers a so far unexplained protection against TBT. Six populations with contrasting DS frequency were sampled; the imposex stage in females and the mean calibre of every vas deferens (VDC) were assessed. While the sex ratio in the 600 specimens examined was close to 1, aphally was more frequent in females than in males (31 and 7%, respectively). VDC was significantly higher in normal than in aphallic (DS) specimens, independently of sex and/or site. It is concluded that the vas deferens imposed by TBT onto DS females is less prone to develop thick enough so as to interfere with normal egg laying.  相似文献   

Along-track gravity anomalies from Geostat and Seasat altimetry: GEBCO overlays     

David T. Sandwell  Miguel B. Ruiz 《Marine Geophysical Researches》1992,14(3):165-205

To provide easy access to the large number of Seastat and Geosat altimeter observations collected over the last decade, we have plotted these satellite altimeter profiles as overlays to the General Bathymetric Chart of the Oceans (GEBCO). Each of the 32 overlays displays along-track gravity anomalies for either ascending (southeast to northwest) or descending (northeast to southwest) altimeter passes. Where Seasat and Geosat profiles coincide, only the more accurate Geosat profiles were plotted. In poorly charted southern ocean areas, satellite altimeter profiles reveal many previously undetected features of the seafloor.  相似文献   

An Interdisciplinary Methodology for the Characterization and Visualization of the Heritage of Roadway Corridors          下载免费PDF全文

Mar Loren‐Méndez  Rafael Mata‐Olmo  Rita Ruiz  Daniel Pinzón‐Ayala 《Geographical review》2016,106(4):489-515

Roads, particularly since the advent of motorized traffic, have hugely impacted contemporary landscapes. Although their significance was noted in the 1980s, specific roadway‐heritage studies are scarce. Research in different disciplines has identified certain features of roads, but an integrated approach to roadway heritage or a consensus on what this constitutes are lacking. This article proposes an interdisciplinary methodology to assess roadway heritage. Roadways are interpreted within the framework of semantic openness that currently characterizes heritage studies, territory being the basic element of interpretation. Rather than a fragmented approach to conservation, the research defines integrated heritage configurations where natural, cultural, and historical features combine to produce a cohesive form of heritage. GIS (Geographical information systems) technology is used with an online database to assess the complexity of roadway heritage. ICT (Information and communications technology) strategies to raise public awareness are outlined. The methodology is applied to assess the historical N‐340 Mediterranean roadway corridor in Spain.  相似文献   

Latent sprawl,divided Mediterranean landscapes: urban growth,swimming pools,and the socio-spatial structure of Athens,Greece     

Luca Salvati  Elena Ridolfi  David Saurí Pujol  Pere Serra Ruiz 《Urban geography》2016,37(2):296-312

Although Mediterranean cities have inherent differences on a local scale, together they offer a kaleidoscopic overview of distinctive morphologies and patterns of socio-spatial segregation. In this study, we explore the distribution of residential swimming pools as indicators of the use of land and water at the metropolitan scale, in relation to recent changes in the socio-spatial structure of a large Mediterranean city (Athens, Greece). Our results indicate a polarized spatial distribution of swimming pools, still considered a luxury affordable only for a minor segment of the Greek population. The analysis highlights the spatial linkages between concentration of residential pools, class segregation and low-density settlements, indicating that the socio-spatial structure of Athens remains characterized by persistent disparities between rich and poor neighborhoods. Comparison with another Mediterranean city (Barcelona) demonstrates the peculiarity of Athens’ recent development as reflected in the fragmented and polarized urban structure. The study provides an alternative reading of recent Mediterranean urban growth by considering pools as a “landmark” for urban sprawl, producing contested landscapes of localized social segregation.  相似文献   

Soil erosion and degradation in a rapidly expanding industrial area of Eastern Mediterranean basin (Thriasio plain,Greece)     

Georgios Sigalos  Vassiliki Loukaidi  Socrates Dasaklis  Paraskevi Drakopoulou  Luca Salvati  Pere Serra Ruiz  Anastasios Mavrakis 《Natural Hazards》2016,82(3):2187-2200

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Geochemistry, geochronology and mineralisation potential of the granites in the Central Iberian Zone: The Jalama batholith     

Casilda Ruiz  Concepción Fernández-Leyva 《Chemie der Erde / Geochemistry》2008,68(4):413-429

The Jalama batholith (Spain and Portugal) is one of the numerous granites of the Central Iberian Zone with Sn- and W-associated mineralisation. On the basis of petrographical and geochemical characterisation three types of granite have been distinguished: inhomogeneous granitoids, porphyrytic granites and leucogranites, all of these being peraluminous and subalkaline. All the granites correspond to S-type granites. The field data, the petrography and lack of geochemical affinity relationships of the leucogranites with the remaining granites indicate that their geneses correspond to an independent magma batch and superimposed fractional crystallisation process. The granitic units show subparallel REE patterns. There is a decrease in total REE and an increase in the negative Eu anomaly from the inhomogeneous granitoids to leucogranites. Some leucogranites show relatively low contents of Sn and W almost certainly due to segregation in the magma of a melt rich in water carrying Sn-W. These elements are concentrated in the water phase, which eventually gives rise to Sn-W-associated mineralisation.The ages obtained by means of a whole-rock Rb-Sr isochron for the granites mainly indicate an early intrusion of the inhomogeneous granitoids (319±10 Ma), followed in time by porphyrytic granites (279±9 Ma), which can be associated to the late-post-kinematic granites within the third Variscan deformation phase (D₃).Apart from the average Sn content, the variations of trace elements, principally Sr, Ba, Rb, Th and P, establish that the porphyritic granites and the inhomogeneous granitoids will be barren granites while the leucogranites and the subfacies at the margin of the porphyritic granites correspond to granites with mineralisation potential. It is precisely in these granites of the Jálama batholith that the Sn-W mineralisation is located, for which the criteria utilised has been demonstrated to be effective.  相似文献   

Geology,Geochemistry and Re–Os systematics of manganese deposits from the Santa Rosalía Basin and adjacent areas in Baja California Sur,México     

R. Del Rio Salas  J. Ruiz  L. Ochoa-Landín  O. Noriega  F. Barra  D. Meza-Figueroa  F. Paz-Moreno 《Mineralium Deposita》2008,43(4):467-482

The manganese ores in the Santa Rosalía region, western Mexico, are mainly stratiform horizons or mantos, constrained to the initial stages of sedimentary cycles of the Miocene Boléo Formation. The manganese mineralization is generally restricted to isolated paleo-basins and related to NW–SE faults formed during the early stages of the opening of the Gulf of California. Jasper, Fe, and Mn oxides associated to the NW–SE structures may represent feeder zones for the mineralized system. The manganese oxide minerals include pyrolusite, cryptomelane, todorokite, hollandite, jacobsite, and pyrochroite. Trace elements in the manganese ores indicate a hydrothermal origin for the deposits of the Santa Rosalía area. Rare earth elements (REE) patterns obtained for manganese minerals from the Lucifer and El Gavilán deposits also support a hydrothermal origin, whereas the middle REE enrichment observed in samples from the Boléo district indicates mixing between hydrothermal and hydrogenous sources. Osmium and rhenium concentrations of the manganese minerals range between 33–173 ppt and 0.14–89 ppb, respectively. The initial ¹⁸⁷Os/¹⁸⁸Os ratios in the manganese oxides from Lucifer and the Boléo district range between 0.43 to 0.51 and 0.70 to 0.74, respectively. These ratios are different from seawater at 7 Ma (0.84–0.89), which suggests important contributions of osmium from underlying rocks such as the Miocene volcanic rocks and the Cretaceous quartz–monzonite basement. Field evidence, manganese oxide mineralogy coupled with major and trace element geochemistry and Re–Os systematics support a hydrothermal origin for the manganese deposits from the Santa Rosalía region. The ore deposition style indicates an exhalative-intraformational environment restricted to isolated basins in a diagenetic stage related to the initial evolution of the Gulf of California.  相似文献   

Hydrogeochemical modeling of organo-metallic colloids in the Nsimi experimental watershed,South Cameroon   总被引：1，自引：0，他引：1  

M. Sekhar  Jean-Jacques Braun  K. V. Hayagreeva Rao  Laurent Ruiz  Henri Robain  Jérôme Viers  Jules Rémy Ndam  Bernard Dupré 《Environmental Geology》2008,54(4):831-841

This paper presents a hydrogeochemical modeling code HYDROS, which combines the multi-component transport model with equilibrium speciation module MINTEQA2. The processes of adsorption, aqueous speciation and mineral precipitation/dissolution are represented in the model. The numerical model uses a sequential iterative approach for solving the solute transport and the equilibrium geochemistry modules. Further the transport part is solved using an operator split approach wherein a finite volume method is used for solving the advective equations while a classical finite difference method is employed for solving the dispersive equations. The model performance is evaluated by comparing it with MINTOX for a literature problem. HYDROS is then applied to the case study of the transfer of transition metals with organic colloids in the swamp groundwater system of the experimental Nsimi watershed, representative of the humid tropical ecosystem of the South Cameroon Plateau. Field observations at the site swamp system suggest that the carbon is mainly transferred as organic colloids (i.e., dissolved organic carbon) produced by the slow biodegradation of the swamp organic matter. Using HYDROS, the behaviour of Al(III) and Fe(III) elements in the base flow system is simulated during inter rain events of a short rainy season (May–June 1996). The elemental time-series for Al, Fe, Cl, pH compare well with the simulation results. The colloids are found to have a strong impact on the mobilization and transfer of Al(III) and Fe(III), which are considered to have low mobility in weathering environment.  相似文献