Comments on “An investigation of seismicity for western Anatolia” by Sayıl and Osmanşahin (2008)     

Yusuf Bayrak 《Natural Hazards》2009,48(1):137-143

  相似文献   

The Use of Neural Networks for the Prediction of Zeta Potential of Kaolinite     

Yusuf Erzin  Yeliz Yukselen 《Mathematical Geosciences》2009,41(7):779-797

The sign and the magnitude of the zeta potential must be known for many engineering applications. For clay soils, it is usually negative, but it is strongly dependent on the pore fluid chemistry. However, measurement of zeta potential time is time-consuming and requires special and expensive equipment. In this study, the prediction of zeta potential of kaolinite has been investigated by artificial neural networks (ANNs) and multiple regression analyses (MRAs). To achieve this, ANN and MRA models based on zeta potential measurements of kaolinite in the presence of salt and heavy metal cations at different pH values have been developed. The results of the models were compared with the experimental results. The performance indices, including coefficient of determination, root mean square error, mean absolute error, and variance, were used to assess the performance of the prediction capacity of the models developed in this study. The obtained indices make it clear that the constructed ANN models were able to predict zeta potential of kaolinite quite efficiently and outperformed the MRA models. Results showed that ANN models can be used satisfactorily to predict zeta potential of kaolinite as a rapid inexpensive substitute for laboratory techniques.  相似文献   

Geotechnical investigations and remediation design for failure of tunnel portal section: a case study in northern Turkey     

Ayberk Kaya  Kadir Karaman  Fikri Bulut 《山地科学学报》2017,14(6):1140-1160

Mass movements are very common problems in the eastern Black Sea region of Turkey due to its climate conditions, geological, and geomorphological characteristics. High slope angle, weathering, dense rainfalls, and anthropogenic impacts are generally reported as the most important triggering factors in the region. Following the portal slope excavations in the entrance section of Cankurtaran tunnel, located in the region, where the highly weathered andesitic tuff crops out, a circular toe failure occurred. The main target of the present study is to investigate the causes and occurrence mechanism of this failure and to determine the feasible remedial measures against it using finite element method (FEM) in four stages. These stages are slope stability analyses for pre- and postexcavation cases, and remediation design assessments for slope and tunnel. The results of the FEM-SSR analyses indicated that the insufficient initial support design and weathering of the andesitic tuffs are the main factors that caused the portal failure. After installing a rock retaining wall with jet grout columns and reinforced slope benching applications, the factor of safety increased from 0.83 to 2.80. In addition to slope stability evaluation, the Rock Mass Rating (RMR), Rock Mass Quality (Q) and New Austrian Tunneling Method (NATM) systems were also utilized as empirical methods to characterize the tunnel ground and to determine the tunnel support design. The performance of the suggested empirical support design, induced stress distributions and deformations were analyzed by means of numerical modelling. Finally, it was concluded that the recommended stabilization technique was essential for the dynamic long-term stability and prevents the effects of failure. Additionally, the FEM method gives useful and reasonably reliable results in evaluating the stability of cut slopes and tunnels excavated both in continuous and discontinuous rock masses.  相似文献   

Levels of Organochlorine Pesticide Residues in Some Organs of the Ganges Perch, Lates calcarifer, from the Ganges–Brahmaputra–Meghna Estuary, Bangladesh     

Sardar Md Abdul Jabber  Yusuf Sharif Ahmed Khan  M. Saifur Rahman 《Marine pollution bulletin》2001,42(12)

Levels of organochlorine pesticide residues (p,p′ DDT, DDD, DDE, Aldrin, Dieldrin, Lindane, Heptachlor and BHC) were analysed in the dry and wet seasons in four organs (muscle, liver, gut and egg samples) of Ganges Perch, Lates calcarifer, collected during October–November–December, 1996 and May–June–July, 1997 from the Ganges–Brahmaputtra–Meghna estuary. The residues were analysed by using gas-chromatography (GC) in electron capture detector (ECD) mode and were verified by thin layer chromatography (TLC). Among the four organs analysed, the residues were found in the order egg > gut > muscle > liver. The pesticide residues were found in the order ∑DDT > Heptachlor >Dieldrin > Aldrin. Higher levels of residues were found during the dry season due to high lipid content in fishes. A positive correlation was observed between the pesticide residues (∑DDT and ∑OCs) and lipid contents of fish, and the correlation was found to be linear. The concentrations of pesticide residues in muscle, liver and gut were below the FAO/WHO (1993) recommended permissible limit except in eggs.  相似文献   

Crowdsourced approaches for stage measurements at ungauged locations using smartphones     

Yusuf Sermet  Paul Villanueva  Muhammed Ali Sit  Ibrahim Demir 《水文科学杂志》2020,65(5):813-822

ABSTRACT

The growing availability of smart devices with advanced sensors has increased the opportunities for citizen science applications for environmental monitoring. Accurate and widespread monitoring of river stage is vital for modeling water resources. Reliable data points are required for model calibration and validation in forecast studies. While current embedded monitoring systems provide accurate measurements, the cost to replicate these systems on a large domain is prohibitively expensive, limiting the quantity of data available. This project describes a new method to accurately measure river levels using smartphone sensors. Pictures of the same point on the river’s surface are taken to perform calculations based on the GPS location and spatial orientation of the smartphone. The proposed implementation is significantly more accessible than existing water measuring systems while offering similar accuracy. A case study is performed to evaluate the accuracy and sensitivity of the measurements to changes in distance.  相似文献   

From transpression to transtension: changes in morphology and structure around a bend on the North Anatolian Fault in the Marmara region     

Aral I. Okay  Okan Tüysüz  inasi Kaya 《Tectonophysics》2004,391(1-4):259

The east–west-trending North Anatolian Fault makes a 17° bend in the western Marmara region from a mildly transpressional segment to a strongly transtensional one. We have studied the changes in the morphology and structure around this fault bend using digital elevation models, field structural geology, and multi-channel seismic reflection profiles. The transpression is reflected in the morphology as the Ganos Mountain, a major zone of uplift, 10 km wide and 35 km long, elongated parallel to the transpressional Ganos Fault segment west of this bend. Flat-lying Eocene turbidites of the Thrace Basin are folded upwards against this Ganos Fault, forming a monocline with the Ganos Mountain at its steep southern limb and the flat-lying hinterland farther north at the flat limb. The sharp northern margin of the Ganos Mountain coincides closely with the monoclinal axis. The strike of the bedding, and the minor and regional fold axes in the Eocene turbidites in Ganos Mountain are parallel to the trace of the Ganos Fault indicating that these structures, as well as the morphology, have formed by shortening perpendicular to the North Anatolian Fault. The monoclinal structure of Ganos Mountain implies that the North Anatolian Fault dips under this mountain at 50°, and this ramp terminates at a decollement at a calculated depth of 8 km. East of this fault bend, the northward dip of the North Anatolian Fault is maintained but it has a normal dip-slip component. This has led to the formation of an asymmetric half-graben, the Tekirdağ Basin in the western Sea of Marmara, containing a thickness of up to 2.5 km of Pliocene to Recent syn-transform sediments. As the Ganos uplift is translated eastwards from the transpressional to the transtensional zone, it undergoes subsidence by southward tilting. However, a morphological relic of the Ganos uplift is maintained as the steep northern submarine slope of the Tekirdağ Basin. The minimum of 3.5 km of fault-normal shortening in the Ganos Mountain, and the minimum of 40 km eastward translation of the Ganos uplift indicate that the present fault geometry has existed for at least the last 2 million years.  相似文献   

Climatic classification of Saudi Arabia: An application of factor -- Cluster analysis   总被引：1，自引：0，他引：1  

Badraddin Yusuf Mohammad Ahmed 《GeoJournal》1997,41(1):69-84

This study is aimed to be a contribution to climatic regionalization of Saudi Arabia. The study applies a multivariate factor -- cluster analysis technique. The data used here have been obtained from 56 meteorological stations. The application of the technique is made into two stages. In the first stage, factor analysis alone is considered and its results in Saudi Arabia are discussed. In the second stage, the resultant factor scores are taken as an input in a cluster analysis process to obtain climatic regions. Thus the regions obtained in the second stage are a result of the integration of factor and cluster techniques. The results obtained by the technique are compared with those of some traditional methods. The factor-cluster analysis technique is found advantageous over many of those methods, as it produces richer regions and shows clear climate variations within this vast country.  相似文献   

Revision of "Leptite-gneisses" in the Menderes Massif: a supracrustal metasedimentary origin     

O. Ö. Dora  O. Candan  O. Kaya  E. Koralay  S. Dürr 《International Journal of Earth Sciences》2001,89(4):836-851

  相似文献   

Stratigraphy and tectono-sedimentary evolution of the Upper Cretaceous–Tertiary sequence in the southern part of the Malatya Basin, East Anatolia, Turkey     

Mehmet nal  Meral Kaya 《Journal of Asian Earth Sciences》2007,29(5-6):878-890

The Malatya Basin is situated on the southern Taurus-Anatolian Platform. The southern part of the basin contains a sedimentary sequence which can be divided into four main units, each separated by an unconformity. From base to top, these are: (1) Permo-Carboniferous; (2) Upper Cretaceous–Lower Paleocene, (3) Middle-Upper Eocene and (4) Upper Miocene. The Upper Cretaceous–Tertiary sedimentary sequence resting on basement rocks is up to 700 m thick.The Permo-Carboniferous basement consist of dolomites and recrystallized limestones. The Upper Cretaceous–Lower Paleocene transgressive–regressive sequence shows a transition from terrestrial environments, via lagoonal to shallow-marine limestones to deep marine turbiditic sediments, followed upwards by shallow marine cherty limestones. The marine sediments contain planktic and benthic foraminifers indicating an upper Campanian, Maastrichtian and Danian age. The Middle-Upper Eocene is a transgressive–regressive sequence represented by terrestrial and lagoonal clastics, shallow-marine limestones and deep marine turbidites. The planktic and benthic foraminifers in the marine sediments indicate a Middle-Upper Eocene age. The upper Miocene sequence consists of a reddish-brown conglomerate–sandstone–mudstone alternation of alluvial and fluvial facies.During Late Cretaceous–Early Paleocene times, the Gündüzbey Group was deposited in the southern part of a fore-arc basin, simultaneously with volcanics belonging to the Yüksekova Group. During Middle-Late Eocene times, the Yeşilyurt Group was deposited in the northern part of the Maden Basin and the Helete volcanic arc. The Middle-Upper Eocene Malatya Basin was formed due to block faulting at the beginning of the Middle Eocene time. During the Late Paleocene–Early Eocene, and at the end of the Eocene, the study areas became continental due to the southward advance of nappe structures.The rock sequences in the southern part of the Malatya Basin may be divided into four tectonic units, from base to top: the lower allochthon, the upper allochthon, the parautochthon and autochthonous rock units.  相似文献   

Seasonal changes of water properties and current in the northernmost gulf of aqaba,red sea     

Riyad Manasrah  Mohammad Zibdah  Firas Al-Ougaily  Najim Yusuf  Tariq Al-Najjar 《Ocean Science Journal》2007,42(2):103-116

Seasonal changes of tide signal(s), temperature, salinity and current were studied during the years 2004-2005 in the northernmost Gulf of Aqaba, which is under developmental activities, to obtain scientific bases for best management and sustainability. Spectrum analysis revealed permanent signals of tide measurements during all seasons, which represented semidiurnal and diurnal barotropic tides. The other signal periods of 8.13, 6.10-6.32, 4.16 and 1.02-1.05 h were not detected in all seasons, which were related to shallow water compound and overtides of principle solar and lunar constituent and to seiches generated in the Red Sea and the Gulf of Aqaba. Spatial and temporal distribution of temperature, salinity and density showed significant differences between months in the coastal and offshore region and no significant differences among the coastal sites, between the surface and bottom waters and between coastal and offshore waters. Therefore, the temporal and spatial variation of water properties in the northernmost Gulf of Aqaba behave similarly compared to other parts. The coastal current below 12 m depth was weak (3-6 cms^-1) and fluctuated from east-northeastward to west-southwestward (parallel to the shoreline), which may be related to the effect of bottom topography and/or current density due to differential cooling between eastern and western parts in the study area, and windinduced upwelling and downwelling in the eastern and western side, respectively. The prevailing northerly winds and stratification conditions during summer were the main causes of the southward current at 6 and 12 m depths with average speed of 28 and 12 cms^-1, respectively.  相似文献