Interpretation of Magnetic Anomalies and Estimation of Depth of Magnetic Crust in Slovakia     

Kamil Rozimant  Aydin Büyüksaraç  Özcan Bektaş 《Pure and Applied Geophysics》2009,166(3):471-484

The magnetic map of Slovakia used in the paper was compiled as part of a project titled Atlas of Geophysical maps and profiles in 2001. The residual magnetic data were analyzed to produce Curie point estimates. To remove distortion of magnetic anomalies caused by the Earth’s magnetic field, reduction to pole transformation was applied to the magnetic anomalies using the magnetization angle of the induced magnetization. Anomalies reduced to the pole tend to be better correlated with tectonic structures. We applied a 3-km upward continuation to the residually compiled magnetic anomalies in order to remove effects of topography. The depth of magnetic dipoles was calculated by an azimuthally averaged power spectrum method for the entire area. Such estimates can be indicative of temperatures in the crust, since magnetic minerals lose their spontaneous magnetization according to Curie temperature of the dominant magnetic minerals in the rocks. The computed Curie point depths in the Slovakia region vary between 15.2 km and 20.9 km. Heat flow higher than 100 mWm⁻² occurs at the central volcanics and eastern part of Slovakia, where the Curie point depths values are shallow. The correlation between Curie point depths, heat flow and crust depth was investigated for two E-W cross sections. Heat flow and Curie point depth values are correlated with each other however, these values could not be correlated with crust depth. The Curie point isotherm, which separates magnetic and non-magnetic parts of the crust, is represented in two cross sections.  相似文献   

Use of microtremor in liquefaction hazard mapping   总被引：1，自引：0，他引：1  

M.A.A. Beroya  A. Aydin  R. Tiglao  M. Lasala 《Engineering Geology》2009,107(3-4):140-153

This study shows how microtremor measurements can be used as an aid to liquefaction hazard mapping and zonation, as demonstrated in Laoag City, Northern Philippines. From microtremor measurements, qualitative information on subsoil conditions was obtained and a site classification map was generated. The map was combined with the geomorphology-based liquefaction susceptibility map to produce an integrated liquefaction hazard zonation map. This integrated map is deemed to be more accurate in depicting relative liquefaction susceptibility since it combines information on the distribution of potentially liquefiable soils in terms of geology and grain characteristics with information on the stiffness and thickness of these soils. With information about the thickness of the deposits, an idea of the severity of liquefaction-related damage can also be gathered since thicker deposits relate to more serious damage. Plots of historical liquefaction cases, as well as borehole data and resistivity profiles in the study area, support the validity of the integrated map. The use of microtremor, therefore, constitutes an effective and inexpensive approach to liquefaction hazard zonation, and as such is very useful in less-developed countries like the Philippines and other areas where funds for more rigorous investigations are not always available.  相似文献   

Spectroscopic study of the eclipsing binary V 367 Cygni     

Aydin  Cemal  Hack  Margherita  Yilmaz  Nihal 《Astrophysics and Space Science》1978,53(2):345-370

Seventeen coudé spectrograms (dispersion 20 A mm^–1) of the Lyrae-type eclipsing binary V 367 Cygni (P=18.6 d) have been studied. The observations were made at the Haute Provence Observatory during a period of almost two years (May 1973–March 1975). An anomalous behavior for the radial velocities of the spectrograms taken during one cycle (406) was observed; it is suggested that gas eruption under form of prominences may explain it. The spectrum is dominated by shell lines very similar to those present in the spectrum of the supergiant A9 Ia Aurigae. The underlying stellar spectrum is classified as A5 I on the basis of the intensity of the sole clearly visible stellar line, 4481 MgII, of the wings of the stellar Balmer lines, and an estimate of the intensity of the stellarK line. The radial velocity curves for the shell lines of CaII, HI, metallic ions and neutral iron, as well as the phase dependence of the microturbulence, indicate stratification in the shell.  相似文献   

    

C. Aydin  H. Demirel 《Journal of Geodesy》2005,78(7-8):437-441

Baardas reliability measures for outliers, as well as sensitivity and separability measures for deformations, are functions of the lower bound of the non-centrality parameter (LBNP). This parameter, which is taken from Baardas well-known nomograms, is actually a non-centrality parameter of the cumulative distribution function (CDF) of the non-central ²-distribution yielding a complementary probability of the desired power of the test, i.e. probability of Type II error. It is investigated how the LBNP can be computed for desired probabilities (power of the test and significance level) and known degrees of freedom. Two recursive algorithms, namely bisection and the Newton algorithm, were applied to compute the LBNP after the definition of a stable and accurate algorithm for the computation of the corresponding CDF. Despite the fact that the recursive algorithms ensure some desired accuracy, it is presented numerically that the Newton algorithm has a faster convergence to the solution than the bisection algorithm.  相似文献   

Top-down modeling and bottom-up dynamics: Linking a fisheries-based ecosystem model with climate hypotheses in the Northern California Current   总被引：3，自引：2，他引：3  

J.C. Field  R.C. Francis  K. Aydin 《Progress in Oceanography》2006,68(2-4):238

In this paper we present results from dynamic simulations of the Northern California Current ecosystem, based on historical estimates of fishing mortality, relative fishing effort, and climate forcing. Climate can affect ecosystem productivity and dynamics both from the bottom-up (through short- and long-term variability in primary and secondary production) as well as from the top-down (through variability in the abundance and spatial distribution of key predators). We have explored how the simplistic application of climate forcing through both bottom-up and top-down mechanisms improves the fit of the model dynamics to observed population trends and reported catches for exploited components of the ecosystem. We find that using climate as either a bottom-up or a top-down forcing mechanism results in substantial improvements in model performance, such that much of the variability observed in single species models and dynamics can be replicated in a multi-species approach. Using multiple climate variables (both bottom-up and top-down) simultaneously did not provide significant improvement over a model with only one forcing. In general, results suggest that there do not appear to be strong trophic interactions among many of the longer-lived, slower-growing rockfish, roundfish and flatfish in this ecosystem, although strong interactions were observed in shrimp, salmon and small flatfish populations where high turnover and predation rates have been coupled with substantial changes in many predator populations over the last 40 years.  相似文献   

A re-configuring sliding-mode controller with adjustable robustness     

Ufuk Demirci  Feza Kerestecio lu 《Ocean Engineering》2004,31(13):5-1682

In this paper, a controller design method for underwater vehicles is presented, which is based on re-configuration of a sliding-mode controller in case of disturbances caused by shallow water conditions. The disturbance distribution information can be obtained and used to update the corrective gain vector of the sliding-mode controller. This increases the robustness of the controller and, hence, keeps the system performance within acceptable limits. Proposed method is validated with simulations on a submarine model.  相似文献   

Evaluation of water quality parameters for the Mamasin dam in Aksaray City in the central Anatolian part of Turkey by means of artificial neural networks   总被引：1，自引：0，他引：1  

Hatim Elhatip  M. Aydin Kömür 《Environmental Geology》2008,53(6):1157-1164

Sustaining the human ecological benefits of surface water requires carefully planned strategies for reducing the cumulative risks posed by diverse human activities. The municipality of Aksaray city plays a key role in developing solutions to surface water management and protection in the central Anatolian part of Turkey. The responsibility to provide drinking water and sewage works, regulate the use of private land and protect public health provides the mandate and authority to take action. The present approach discusses the main sources of contamination and the result of direct wastewater discharges into the Melendiz and Karasu rivers, which recharge the Mamasın dam sites by the use of artificial neural network (ANN) modeling techniques. The present study illustrates the ability to predict and/or approve the output values of previously measured water quality parameters of the recharge and discharge areas at the Mamasin dam site by means of ANN techniques. Using the ANN model is appreciated in such environmental research. Here, the ANN is used for estimating if the field parameters are agreeable to the results of this model or not. The present study simulates a situation in the past by means of ANN. But in case any field measurements of some relative parameters at the outlet point “discharge area” have been missed, it could be possible to predict the approximate output values from the detailed periodical water quality parameters. Because of the high variance and the inherent non-linear relationship of the water quality parameters in time series, it is difficult to produce a reliable model with conventional modeling approaches. In this paper, the ANN modeling technique is used to establish a model for evaluating the change in electrical conductivity (EC) and dissolved oxygen (DO) values in recharge (input) and discharge (output) areas of the dam water under pollution risks. A general ANN modeling scheme is also recommended for the water parameters. The modeling process includes four main stages: (1) source data analysis, (2) system priming, (3) system fine-tuning and (4) model evaluation. Results of the ANN modeling scheme indicate that the output values are agreeable to the water quality parameters, which were measured at the field in the static water mass of the Mamasın dam lake. Water contamination at the dam site is caused by the continuous increase of nutrient contents and decrease of the O₂ level in water causing an anaerobic condition. It may stimulate algae growth flow in such water bodies, consequently reducing water quality.  相似文献   

Upgraded ISRM Suggested Method for Determining Sound Velocity by Ultrasonic Pulse Transmission Technique     

Adnan Aydin 《Rock Mechanics and Rock Engineering》2014,47(1):255-259

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The role of in situ stress in determining hydraulic connectivity in a fractured rock aquifer (Australia)     

Luke Mortimer  Adnan Aydin  Craig T. Simmons  Graham Heinson  Andrew J. Love 《Hydrogeology Journal》2011,19(7):1293-1312

Fracture network connectivity is a spatially variable property that is difficult to quantify from standard hydrogeological datasets. This critical property is related to the distributions of fracture density, orientation, dimensions, intersections, apertures and roughness. These features that determine the inherent connectivity of a fracture network can be modified by secondary processes including weathering, uplift and unloading and other mechanisms that lead to fracture deformation in response to in situ stress. This study focussed on a fractured rock aquifer in the Clare Valley, South Australia, and found that fracture network connectivity could be discriminated from several geological, geophysical and hydrogeological field datasets at various scales including single well and local- to regional-scale data. Representative hydromechanical models of the field site were not only consistent with field observations but also highlighted the strong influence of in situ stress in determining the distribution of fracture hydraulic apertures and the formation of hydraulic chokes that impede fluid flow. The results of this multi-disciplinary investigation support the notion that the hydraulic conductivity of a fracture network is limited to the least hydraulically conductive interconnected fractures, which imposes a physical limit on the bulk hydraulic conductivity of a fractured rock aquifer.  相似文献   

Wear Performance of Saw Blades in Processing of Granitic Rocks and Development of Models for Wear Estimation   总被引：1，自引：0，他引：1  

Gokhan Aydin  Izzet Karakurt  Kerim Aydiner 《Rock Mechanics and Rock Engineering》2013,46(6):1559-1575

This study investigates the wear performance of diamond circular saw blades in cutting of granitic rocks. An alternative wear measuring method is developed to measure the reduced blade radius without taking the blade off the machine. The effect on and contribution to the specific wear rate (SWR) of each operating variable are determined, and the SWR is correlated with rock properties. Morphologies of wearing surfaces of segments and rocks are also evaluated using scanning electron microscopy (SEM). Depending on both operating variables and rock properties, prediction models are developed for estimation of the SWR. Results show that the SWR increases with an increase in the peripheral speed and the traverse speed, while it decreases with an increase in the cutting depth and the flow rate of the cooling fluid. The peripheral speed, and the microhardness and proportions of minerals such as quartz, plagioclase, and feldspar are statistically determined as the significant variables affecting the SWR. Finally, it is disclosed that models developed for estimation of SWR have great potential for practical applications.  相似文献