Using multiple portable/wearable devices for enhanced misalignment estimation in portable navigation

Global navigation satellite system (GNSS), such as global positioning system (GPS), has been widely used for vehicular and outdoor navigation. Accuracy is one, among many, of the advantages of using GNSS in the open sky. However, GNSS finds difficulty in achieving similar results in portable navigation, where users spend most of their time indoors or in urban canyons, places where GNSS signals suffer from multipath error or signal blockage. One of the most common solutions for providing location services in such challenging environments is integrating GNSS with inertial sensors, such as accelerometers and gyroscopes. However, the arbitrary orientation of the portable device can present a more difficult challenge when using inertial sensors for portable navigation. In order to obtain a navigation solution using inertial sensors, an accurate heading estimation is required. Resolving the heading misalignment angle between the portable navigation device and the moving platform, such as using the device while walking or in a vehicle while driving, is critical to obtaining an accurate heading estimation. We present a solution for resolving the misalignment between the portable device and the moving platform, which exploits multiple portable devices like smartphones or tablets and/or smart wearable devices such as smart watches, smart glasses, and/or smart fitness and activity trackers/monitors. Several real field test experiments using portable devices were conducted to examine the performance of the proposed method. Results show how a portable navigation solution can be improved by further enhancing misalignment estimation.     

Reconstructing Phreatic Palaeogroundwater Levels in a Geoarchaeological Context: A Case Study in Flanders,Belgium

The complex debate on prehistoric settlement decisions is no longer tackled from a purely archaeological perspective but from a more landscape‐oriented manner combined with archaeological evidence. Therefore, reconstruction of several components of the former landscape is needed. Here, we focus on the reconstruction of the groundwater table based on modeling. The depth of the phreatic aquifer influences, for example, soil formation processes and vegetation type. Furthermore, it directly influences settlement by the wetness of a site. Palaeogroundwater modeling of the phreatic aquifer was carried out to produce a series of full‐coverage maps of the mean water table depth between 12.7 ka and the middle of the 20th century (1953) in Flanders, Belgium. The research focuses on the reconstruction of the input data and boundary conditions of the model and the model calibration. The model was calibrated for the 1924–1953 time period using drainage class maps. Archaeological site data and podzol occurrence data act as proxies for local drainage conditions over periods in the past. They also served as a control on the simulated phreatic palaeogroundwater levels. Model quality testing on an independent validation data set showed that the model predicts phreatic water table levels at the time of soil mapping well (mean error of 1.8 cm; root mean square error of 65.6 cm). Simulated hydrological conditions were in agreement with the occurrence of archaeological sites of Mesolithic to Roman age at 96% of the validation locations, and also with the occurrence of well‐drained podzols at 97% of the validation locations.     

Biogéographie des ammonites jurassiques et reconstitution palinspastique de la Téthys

Résumé

— La distribution géographique des ammonites jurassiques est régie par deux causes fondamentales : l’écologie et l’histoire évolutive (événements vicariants). L’analyse conjointe de ces deux facteurs permet de reconnaître : d’une part des taxons dont la distribution est essentiellement contrôlée par des contraintes écologiques (Phylloce-ratinae et Lytoceratinae, liés à des environnements océaniques profonds; Clydoniceratidae et Proplanulitinae liés à des plates-formes assez superficielles); d’autre part des taxons dont l’histoire évolutive est associée à des événements vicariants (Ammonitina liasiques euro-boréales et Cardioceratidae-Kosmoceratidae boréaux du Jurassique moyen).

Les exemples développés ici permettent d’analyser en terme de paléobiogéographie la position de l’Europe centro-méridionale (Bulgarie, Hongrie, Roumanie) incluse au Jurassique dans la bordure nord-téthy-sienne. Il est montré que Phylloceratinae et Lytoceratinae sont très abondants dans les régions supposées profondes à cette époque (sphéno-chasme des monts d’Apuseni, sillon Dobrogeo-Caucasien), alors qu’elles sont très rares sur la plate-forme moësienne. La même remarque est valable pour les plates-formes moyennes-orientales de la marge sud (Israël, Arabie Saoudite).

Lorsque l’on tente d’établir des reconstructions palinspastiques basées sur la paléobiogéographie, on constate que les taxons qui ont une histoire évolutive originale fournissent de meilleures informations paléogéographiques que les formes ubiquistes ou celles à préférences écologiques accusées. Les données brutes de répartition des faunes d’ammonites ne sont donc pas des arguments absolus pour corroborer les reconstructions. Les analyses fauniques, conduites avec une approche qualitative et quantitative, doivent tenir compte de données extra-biologiques telles que la distribution des faciès et des unités structurales; enfin, le niveau d’intervention — local, régional, global — conditionne fortement les possibilités d’interprétation des résultats.     

Mesozoic paleostress evolution in the Saharian platform (southern Tunisia)

Abstract

A detailed analysis of brittle deformations in the Saharian platform of southern Tunisia is based on studies of fault-slip data sets and joint sets. It allows reconstruction of the Mesozoic paleostress evolution. During the Permo-Triassic, N-S extensions occurred with high late Permian subsidence rates. During the Norian, strike-slip movements reactivated former normal faults. During the Jurassic and the Cretaceous a succession of extensional events was characterized by : (1) a N-S extension which dominated from late Triassic to early Aptian. We relate this extension to the Africa-Eurasia divergence; (2) a ENE-WSW extension during the Cenomanian. We relate this extension to the opening of «he African basins ; (3) a NE-SW Senonian extension that continued during the Cenozoic in the Jeffara and in the Gabes Gulf, during the further evolution of the northern African margin. The various compressional trends recorded in the platform are attributed to Cenozoic events.     

The intensification of the East Asian winter monsoon contributed to the disappearance of Cedrus (Pinaceae) in southwestern China

Climate change during the Quaternary played an important role in the distribution of extant plants. Herein, cone scales of Cedrus (Pinaceae) were uncovered from the Upper Pliocene Sanying Formation, Longmen Village, Yongping County of Yunnan Province in southwestern China. Detailed comparisons show that these fossils all belong to the genus Cedrus (Pinaceae), and a new species is proposed, Cedrus angusta sp. nov. This find expands the known distribution of Cedrus during the Late Pliocene to Yunnan, where the genus no longer exists in natural forests. Based on the analysis of reconstructed Neogene climate data, we suggest that the intensification of the East Asian winter monsoon during the Quaternary may have dramatically increased seasonality and given rise to a much drier winter in Yunnan. Combined with information on Cedrus fossil records and its seed physiology, we conclude that the intensification of a drier climate after the Late Pliocene may have prevented the survival of Cedrus seedlings, leading to the eventual disappearance of Cedrus in western Yunnan. This study indicates that the topography in southwestern China acted as a vital refuge for many plants during the Quaternary, but that other species gradually disappeared due to the intensification of the monsoonal climate.     

The applications of high resolution satellite data for coastal management and planning in a pacific coral Island

Abstract

Coastal Tropism is a worldwide phenomenon. It induces urgent needs for observation inventories and management of coastal environment, mainly in developing countries.

High resolution satellite data may solve some aspects of the problems. Three examples based upon the potential use of shrimp aquaculture sites in tropical salt marshes, the biotopes mapping in coral reef environments for biologic stock assessments and the characterization and quantification of evolutive stages of coral platforms, are developed. All three are relative to the same tropical Pacific Island with respect, for the first and second examples, to actual needs for the management of mangroves and coral reefs and for the third, to a scientific approach related to evolutive theory of reefs platforms in lagoons.

Methodology and results based upon digital image processing and computer assisted photointerpretation are exposed.

New trends in digital processing and associated digital cartography are listed.     

Effects of Foreshortening on Shallow Sub-surface Flows Observed with Local Helioseismology

From the results given in a recent paper by Zaatri et al. (2006, Solar Phys. 236, 227) it is clear that foreshortening effects play a major role in estimating the magnitude and direction of meridional and other flows in the shallow solar sub-surface layers using local helioseismology. Using a different algorithm to account for these effects I arrive at a significantly different estimate for the meridional flows.     

The 1995–2002 Long-Term Monitoring of Comet C/1995 O1 (HALE–BOPP) at Radio Wavelength

The bright comet Hale–Bopp provided the first opportunity to follow the outgassing rates of a number of molecular species over a large range of heliocentric distances. We present the results of our observing campaign at radio wavelengths which began in August 1995 and ended in January 2002. The observations were carried out with the telescopes of Nançay, IRAM, JCMT, CSO and, since September 1997, SEST. The lines of nine molecules (OH, CO, HCN, CH₃OH, H₂CO, H₂S, CS, CH₃CN and HNC) were monitored. CS, H₂S, H₂CO, CH₃CN were detected up to r_h= 3–4 AU from the Sun, while HCN and CH₃OH were detected up to 6 AU. CO, which is the main driver of cometary activity at heliocentric distances larger than 3–4 AU, was last detected in August 2001, at r_h= 14 AU. The gas production rates obtained from this programme contain important information on the nature of cometary ices, their thermal properties and sublimation mechanisms.Line shapes allow to measure gas expansion velocities, which, at large heliocentric distances, might be directly connected to the temperature of the nucleus surface. Inferred expansion velocity of the gas varied as r_h ^-0.4 within 7 AU from the Sun, but remained close to 0.4 km s^-1 further away. The CO spectra obtained at large r_hare strongly blueshifted and indicative of an important day-to-night asymmetry in outgassing and expansion velocity. The kinetic temperature of the coma, estimated from the relative intensities of the CH₃OH and CO lines, increased with decreasing r_h, from about 10 K at 7 AU to 110 K around perihelion.     

Geochemical evidence of hydrothermal recharge in Lake Baringo,central Kenya Rift Valley

Lake Baringo, a freshwater lake in the central Kenya Rift Valley, is fed by perennial and ephemeral rivers, direct rainfall, and hot springs on Ol Kokwe Island near the centre of the lake. The lake has no surface outlet, but despite high evaporation rates it maintains dilute waters by subsurface seepage through permeable sediments and faulted lavas. New geochemical analyses (major ions, trace elements) of the river, lake, and hot spring waters and the suspended sediments have been made to determine the main controls of lake water quality. The results show that evaporative concentration and the binary mixing between two end members (rivers and thermal waters) can explain the hydrochemistry of the lake waters. Two zones are recognized from water composition. The southern part of the lake near sites of perennial river inflow is weakly influenced by evaporation, has low total dissolved species (TDS), and has a seasonally variable load of mainly detrital suspended sediments. In contrast, waters of the northern part of the lake show evidence for strong evaporation (TDS of up to eight times inflow). Authigenic clay minerals and calcite may be precipitating from those more concentrated fluids. The subaerial hot‐spring waters have a distinctive chemistry and are enriched in some elements that are also present in the lake water. Comparison of the chemical composition of the inflowing surface waters and lake water shows (1) an enrichment of some species (HCO₃^?, Cl, SO₄^2?, F, Na, B, V, Cr, As, Mo, Ba and U) in the lake, (2) a depletion in SiO₂ in the lake, and (3) a possible hydrothermal origin for most F. The rare earth element distribution and the F/Cl and Na/Cl ratios give valuable information on the rate of mixing of the river and hydrothermal fluids in the lake water. Calculations imply that thermal fluids may be seeping upward locally into the lake through grid‐faulted lavas, particularly south of Ol Kokwe Island. Copyright © 2006 John Wiley & Sons, Ltd.     

Families of Periodic Orbits Emanating From Homoclinic Orbits in the Restricted Problem of Three Bodies

We describe and comment the results of a numerical exploration on the evolution of the families of periodic orbits associated with homoclinic orbits emanating from the equilateral equilibria of the restricted three body problem for values of the mass ratio larger than μ ₁. This exploration is, in some sense, a continuation of the work reported in Henrard [Celes. Mech. Dyn. Astr. 2002, 83, 291]. Indeed it shows how, for values of μ. larger than μ ₁, the Trojan web described there is transformed into families of periodic orbits associated with homoclinic orbits. Also we describe how families of periodic orbits associated with homoclinic orbits can attach (or detach) themselves to (or from) the best known families of symmetric periodic orbits. This revised version was published online in July 2006 with corrections to the Cover Date.