A weak approximation of stochastic time domain electromagnetic response of a conductive permeable sphere

Time domain electromagnetic (TDEM) response of a conductive permeable sphere is a main topic for good understanding and in developing past studies for detection and discrimination of buried metallic objects. Stochastic differential equation model is a valuable tool for stimulating real experience. In this paper, according to an Itô integral, we have obtained a weak approximation of stochastic TDEM response of permeable and nonpermeable sphere. We have used the deterministic solution of TDEM response of conductive permeable sphere by changing one of the variables that have been obtained from the boundary conditions of problem to random variable. By adding white noise to random variable and using stochastic integral, we have displayed stochastic time domain response of conductive permeable sphere. The Itô integral includes a factor that shows infirmity and intensity of noise which has been simply considered constant. Accordingly, we have showed the effect of noise for magnetic and nonmagnetic spheres. Numerical results from step and impulse response of TDEM have shown that the amount of this factor is different for the two types of spheres.     

Geohistory analysis and basin development of the Neogene succession, NE Iraq

The Neogene succession in the studied area is represented by seven formations (Serikagni, Euphrates, Dhiban, Jeribe, Fatha, Injana, and Muqdadiya formations). The area of study is located in the Unstable Shelf within the Low Folded Zone and the north part of the Stable Shelf (Mesopotamian Zone). This study included the geohistory analysis of the Neogene succession and interpretation the changes of the accumulation and subsidence rates and compared them with the space available to explanation the basin development. At The Early Miocene (Aquitanian age), the Sirekagni and Euphrates formations was deposited during a major transgression with high rates of subsidence and accumulation in the Himreen, Makhul, and north of Tigris subzones, while the Chemchemal–Arbil and Butmah–Mosul subzones were positive areas. This period ended with a sea withdrawal to the southeast to generate the Dhiban lagoonal basin which was characterized by low accumulation and subsidence rates. During the Early Burdigalian, the Jeribe Formation was deposited during another sea level rise that covered the area except the Chemchemal–Arbil and Butmah–Mosul subzones representing the uplifted positive area. The sea level rise continued to the early Langhian age where the transition beds for the Fatha Formation was deposited to mark the maximum flooding surface covering all the study area. The Fatha Formation was deposited at the Late Langhian to the Early Serravallian during sea level stillstand with high accumulation and subsidence rates in the Himreen subzone and the Chemchemal–Arbil subzone. This period ended without a clear tectonic activity. The period from Late Miocene to Pliocene was characterized by high tectonic activity and sea level fall where fluvial–lacustrine environment prevailed to deposit the Injana and Muqdadiya formations. The Injana Formation was deposited during the Late Serravallian–Tortonian in the Himreen and Chemchemal–Butmah subzones; in addition to the northern part of Tigris subzone. The areas of high rates of accumulation and subsidence were located near Jambour while the southwestern part was affected by an uplift generating the Himreen structure. The Chemchemal–Butmah subzones was characterized by a high uplift in the southeast part where Kirkuk and Chemchemal structures were forming, while The northeastern part (from Bi Hassan to the borehole Kirkuk-117) was with low accumulation and subsidence rates. The linear region between these parts (Khabaz oil field) showed an abnormal values for accumulation and subsidence rates (very high); this region corresponds to the location and direction of Anah–Fatha–Qalat Dizah Fault which suggest that the fault was active during that time. The tectonic activity continued to uplift all the north of the study area as well as the West and the East during the Late Tortonian to the Piacenzian where the Muqdadiya Formation was deposited in the area between Jambour to Khabaz oilfields. Then the succession was deformed and uplifted to approximately 800 m above the sea level as in the present day.     

Mapping of landslide hazard zonation using GIS at Golestan watershed, northeast of Iran

Landslide hazard zonation is essential for planning future developmental activities. At the present study, after the preparation of a landslide inventory of the study area, nine factors as well as sub-data layers of factor class weights were tested for an integrated analysis of landslide hazard in the region. The produced factor maps were weighted with the analytic hierarchy process method and then classified into four classes—negligible, low, moderate, and high. The final produced map for landslide hazard zonation in Golestan watershed revealed that: (1) about 53.85 % of the basin is prone to moderate and high threats of landslides. (2) Landslide events at the Golestan watershed were strongly correlated to the slope angle of the basin. It was observed that the active landslide zones, including moderate to high landslide hazard classes, have a high correlation to slope classes over 30° (R ²?=?0.769). (3) The regions most susceptible to landslide hazard are those located south and southwest of the watershed, which included rock topples, falls, and debris landslides.     

Effect of the groundwater contribution, the climatic change, and the human-induced activities on the hydrological behavior of discharge playas: a case study Sidi El Hani discharge playa, Tunisian Sahel

This study is meant to provide an insight into how discharge playas, which are strongly influenced by a regional salty groundwater flow regime, such as the discharge playa of Sidi El Hani, would respond to the climatic variability and to the materials coming from the subsurface of the Sahel area. In order to choose the appropriate method, a special care was given in this paper to different methods of investigation of the groundwater contribution in water and salt budgets of saline systems. The hydrogeological map of the surrounding aquifers proved their convergence toward Sidi El Hani discharge playa. As consequence of the dominance of a salty groundwater contribution, the climate variability may be considered minor. Accordingly, the model proposed by this study showed the dominance of the salty water coming from the hydrogeology at the expense of the fresh water coming from the climatic contribution. Moreover, according to the adopted model, the effect of the human-induced activity on the hydrogeological contribution such as the installation of dams in the Tunisian center and the overexploitation of the phreatic aquifer of Kairouan was judged increasing the convergence of Kairouan aquifer towards Sidi El Hani discharge playa. On the other hand, the consumption of salt reserves from the discharge playa tends to decrease its salinization.     

Hydrodynamic study of karstic and intergranular aquifers using isotope geochemistry in Basara basin, Sulaimani, North-Eastern Iraq

The study area is located in the border of the high and low folded zone having a semi-arid climate area. This study initiated in 2009–2010, deals essentially with the investigation of the stable isotope (¹⁸O and deuterium ²H) as well as radioactive isotope represented by tritium ³H in rain, carbonate springs, intergranular aquifer, and surface water in order to investigate the source and relative ages of the groundwater and to show the influence of the altitude variations of the isotope composition. In this study and for the first time in the area, a local meteoric water line have been drawn with an empirical formula δ ²H?=?7.7δ ¹⁸O?+?14.4. The δ ¹⁸O–altitude effect was determined using isotopic data for several samples taken from groundwater and surface water; it was approximated at ?0.79?‰/100 m for the entire area of the study. The output of the tritium concentrations in the springs and water well samples revealed to the conclusion that the values closely resembles to the present time tritium concentration in precipitation.     

Deterministic and probabilistic seismic hazard analysis for Gwadar City, Pakistan

Gwadar City is located at the coastline of Pakistan. The city is currently in a phase of development, which is expected to become a future economic hub for Pakistan. This has led us to choose Gwadar for seismic hazard evaluation. Seismic hazard analysis for Gwadar is carried out using deterministic and probabilistic seismic hazard analysis techniques. The present study will help in sustainable development of a future large city and economic hub for Pakistan on ways of coping from a major threat of earthquake hazard. In deterministic seismic hazard analysis, line sources were identified close to Gwadar. Based on the analysis of maximum magnitude and closest distance (worse conditions), Makran subduction zone was identified out of all the line sources with earthquake potential of 8.2 at a distance of 30 km. This yielded a peak ground acceleration value of 0.38 g for Gwadar City. In second phase, probabilistic seismic hazard analysis technique with the area source modeling was adopted to acquire results at different return periods. For this purpose, seismic data were collected from the Pakistan Meteorological Department and International Seismological Center (2010) databases for development of a comprehensive data catalog. The a and b values were obtained using regression analysis for each source zone, and probabilistic analysis yielded the results of 0.34 g for a return period of 500 years. As per building codes of Pakistan, areas or cities with ground acceleration greater than 0.32 g are considered in seismic zone 4, and both deterministic and probabilistic hazard analysis place the city in seismic zone 4. These values correspond to rock site with shear wave velocity of 760 m/s.     

Flash flood inundation map preparation for wadis in arid regions

Flood inundation maps are dependent on the topographic and geomorphologic features of a wadi (drainage basin) in arid regions, which are most susceptible for potential flash flood occurrences, such as in the southwestern part of the Kingdom of Saudi Arabia. It is not possible to control the potential flood hazards by using only technological instruments that forewarn the occurrences or imminence. Additionally, it would be better to prepare flood risk maps so as to delineate the risky areas to educate the administrators and local settlers. The availability of these maps is the key requirement for any urban development that entails land use allocation, identification of dam, tunnel, highway, bridge sites, and infrastructure locations for sustainable future. This paper suggests the necessary steps in flood inundation map preparation after determining the possible flood discharge. For this purpose, a set of critical cross-sections along the possible flood plain are taken in the field with surveying methods and measurements. The calculation of the average flow velocity in each section is calculated according to the cross-section geometric, hydraulic, and material properties. Synthetic rating curves (SRC) are prepared for each cross section, which are very useful especially in arid and semi-arid regions where there are no perennial surface water flows for natural rating curve measurements. All the SRCs appear in the form of power function which relates the flow depth to discharge in a given cross section. It is then possible to calculate the flood depth in the cross section through its SRC. Depending on the cross-section shape, the flood width can be calculated. The connection of a series of widths on a scaled topographic map delineates the flood inundation area. If digital elevation map (DEM) is available, then the SRCs can be integrated with these maps and the flood inundation delineation can be achieved automatically. Since DEMs are not available, the topographic maps are used for this purpose in order to delineate flood inundation areas within wadis Hali and Yiba from the southwestern Kingdom of Saudi Arabia.     

Oil formation volume factor modeling: Traditional vs. Stochastically optimized neural networks

Oil formation volume factor (FVF) is considered as relative change in oil volume between reservoir condition and standard surface condition. FVF, always greater than one, is dominated by reservoir temperature, amount of dissolved gas in oil, and specific gravity of oil and dissolved gas. In addition to limitations on reliable sampling, experimental determination of FVF is associated with high costs and time-consumption. Therefore, this study proposes a novel approach based on hybrid genetic algorithm-pattern search (GA-PS) optimized neural network (NN) for fast, accurate, and cheap determination of oil FVF from available measured pressure-volume-temperature (PVT) data. Contrasting to traditional neural network which is in danger of sticking in local minima, GA-PS optimized NN is in charge of escaping from local minima and converging to global minimum. A group of 342 data points were used for model construction and a group of 219 data points were employed for model assessment. Results indicated superiority of GA-PS optimized NN to traditional NN. Oil FVF values, determined by GA-PS optimized NN were in good agreement with reality.     

Axially Symmetric Bianchi Type-I Bulk-Viscous Cosmological Models with Time-Dependent Λ and q

The present study deals with spatially homogeneous and anisotropic axially symmetric Bianchi type-I cosmological model with time variable cosmological term Λ in the presence of bulk viscous fluid. The Einstein’s field equations are solved explicitly by time varying deceleration parameter q. Consequences of the four cases of phenomenological decay of Λ have been discussed which are consistent with observations. Physical and kinematical parameters of the models are discussed.     

EPC: Matlab software to estimate Euler pole parameters

The estimation of Euler pole parameters has always been an important issue in global tectonics and geodynamics studies. In addition, the increasing number of permanent GPS stations and the ease of access to their data, along with advances in computers, promise new methods and tools for the estimation and the quantitative analysis of Euler pole parameters. Therefore, we developed the Euler pole calculator software using a set of mathematical algorithms based on the model of tectonic plate motion on a spherical surface. The software is able to calculate the expected velocities for any points located on the earth’s surface given the relevant Euler pole parameters and to estimate the Euler pole parameters given the observed velocities of a set of sites located on the same tectonic plate. Mathematical algorithms and functions of the software are explained in detail.