A regularization of multiple encounters in gravitationalN-body problems

A method is introduced to regularize binary collisions between one of the bodies and any number of other bodies in the three-dimensional problem ofn-bodies. The coordinates are first transformed from an inertial system to a system relative to one of the bodies. The KS dependent variable transformation and a new independent variable transformation are introduced for the regularization.     

Solutions for Exterior Orientation in Photogrammetry: A Review

The determination of the attitude, the position and the intrinsic geometric characteristics of the camera is recognised as the fundamental photogrammetric problem. It can be summarised as the determination of camera interior and exterior orientation parameters, as well as the determination of 3D coordinates of object points. The term "exterior orientation"of an image refers to its position and orientation related to an exterior (object space) coordinate system. Several methods can be applied to determine the parameters of the orientation of one, two or more photos. The orientation can be processed in steps (as relative and absolute orientation) but simultaneous methods (such as bundle adjustments) are now available in many software packages. Several methods have also been developed for the orientation of single images. They are based in general on geometric and topological characteristics of imaged objects.
This paper presents a survey of classical and modern methods for the determination of the exterior parameters in photogrammetry, some of which are available as software packages (with practical examples) on the Internet. The methods presented are classified in three principal groups. In the first, a selection of approximate methods for applications that do not require great accuracy is presented. Such methods are also used to calculate values required for iterative processes. In the second group, standard point–based methods derived from collinearity, coplanarity or coangularity conditions are briefly reviewed, followed by line–based approaches. The third group represents orientation methods based on constraints and on concepts of projective geometry, which are becoming of increasing interest for photogrammetrists. In the last section, the paper gives a summary of existing strategies for automatic exterior orientation in aerial photogrammetry.     

Earth Fissures Caused By Groundwater Withdrawal In Sarir South Agricultural Project Area,Libya

arir South agricultural well field consists of 157 production wells constructed in double rows running east to west. Each well was designed to pump 76 l/sec to irrigate 80 hectares of winter and summer crops. Large volumes of water have been pumped from the aquifer since 1975. By 1990, water levels in the most heavily pumped areas had declined more than 6 meters. These large water-level declines have caused compaction of compressible fine-grained deposits within the aquifers. Earth fissures were reported in the Sarir South agricultural project as early as 1982. These fissures were mainly caused by lowering of the piezometric heads due to the withdrawal of groundwater. The fissures range in width from 2.5 cm to 100 cm on the surface and, generally, become narrower with depth. However, the total depth is not known for any of the fissures. Development of new cracks or fissures near the old ones has also been observed. Most of the recent fissures occur parallel and immediately adjacent to the older fissures. It appears that these fissures tend to develop into a linear fissure system in a north-south direction. Résumé. Le champ captant du sud de Sarir, destiné à l'irrigation, est constitué de 157 puits d'exploitation, disposés en deux rangées orientées est-ouest. Chaque puits est équipé pour pomper 76 l/sec pour irriguer 80 ha de cultures d'hiver et d'été. Des volumes considérables d'eau ont ainsi été pompés dans l'aquifère principal depuis 1975. Depuis 1990, le niveau piézométrique dans les zones les plus sollicitées est descendu de plus de 6 m. Cet abaissement important a provoqué dans les aquifères une compaction des dépôts compressibles à grains fins. Dès 1982, le sol de cette région s'est fissuré. Ces fissures proviennent pour la plupart de l'abaissement de la surface piézométrique sous l'effet du pompage de l'eau souterraine. Ces fissures sont larges de 2.5 à 100 cm, en surface et se rétrécissent en profondeur. Leur profondeur totale n'est pas connue. De nouvelles fissures apparaissent au voisinage des anciennes. La plupart d'entre elles sont parallèles et adjacentes aux anciennes. Engin, les fissures tendent à former un ensemble linéaire orienté nord-sud.     

Differences in the concentrations of atmospheric trace gases in and above the tropical boundary layer

Weekly air samples were collected at Cape Kumakahi (0 km) and at nearby Mauna Loa Observatory (3.4 km) which is above the boundary layer. EC/GC and GC/FID techniques were used to measure CH₃I, CHCl₃, CO and CH₄, which are largely natural in origin, and C₂Cl₄, CCl₄, CH₃, CCl₃, CCl₃F (F-11), CCl₂F₂ (F-12), CHClF₂ (F-22) and C₂F₃Cl₃ (F-113), which are due to anthropogenic activities. It was found that all these gases are significantly (0.05) more abundant in the boundary layer than above it.     

Comparison of SEBAL,METRIC, and ALARM algorithms for estimating actual evapotranspiration of wheat crop

Theoretical and Applied Climatology - Evapotranspiration is one of the main components of water balance and its accurate estimation is of great importance in planning and optimizing water...     

Spatial and temporal analysis of the drought vulnerability and risks over eight decades in a semi-arid region (Tensift basin: Morocco)

Theoretical and Applied Climatology - The multiple downscaled scenario products allow us to assess the uncertainty of the variations of precipitation and temperature in the current and future...     

Inverse geochemical modeling of groundwater salinization in Azraq Basin,Jordan

The aim is to define the mechanism of chemical reactions that are responsible for the salinization of the Azraq basin along groundwater flow path, using inverse modeling technique by PHREEQC Interactive 2.8 for Windows. The chemical analysis of representative groundwater samples was used to predict the causes of salinization of groundwater. In addition, the saturation indices analysis was used to characterize the geochemical processes that led to the dissolution of mineral constituents within the groundwater aquifer system. According to the modeling results, it was noted that the groundwater at the recharge area was undersaturated with respect to calcite, dolomite, gypsum, anhydrite, and halite. Thus, the water dissolved these minerals during water rock interaction, and therefore, the concentration of Ca, Mg, Na, and SO₄ increased along the groundwater flow path. Furthermore, the groundwater at the discharge area was oversaturated with respect to calcite and dolomite. This meant that the water would precipitate these minerals along the flow path, while the water was undersaturated with respect to gypsum and halite throughout the simulated path; this showed the dissolution processes that take place during water-rock interaction. Therefore, the salinity of the groundwater increased significantly along the groundwater flow paths.