Responses of the stratified flows to their driving conditions—A field study     

Yalcin Yuksel  Berna Ayat  Mehmet Nuri Ozturk  Burak Aydogan  Isikhan Guler  Esin Ozkan Cevik  Ahmet Cevdet Yalçıner 《Ocean Engineering》2008,35(13):1304-1321

The Bosphorus is oceanographically very complicated two-layer stratified strait where denser water from the Marmara Sea flows towards North under the lighter water which is frequently flowing from the Black Sea towards South. The water level difference between both ends of the Bosphorus varies seasonally within the range of ?0.2 and 0.6 m. The seasonal variability depends mainly on the water level changes in the adjacent basins related to the hydrological cycle, short-term changes in the atmospheric pressure and the wind characteristics. These variations together with the depth and alignment of the cross section along the strait dominate the spatial and temporal variations and sometimes sharp changes in the flow pattern in three dimensions. Although these hydrodynamic conditions are critical for all marine and hydraulic works along the Bosphorus, there was not continuous long-term measurement for a sufficient time span in the strait for detailed evaluation of the current climate. An extensive site surveying work including current, wind, pressure and water level measurements was carried out between September 2004 and January 2006 in relation to the design and construction requirements of the Bosphorus Tube Crossing Project. In this study, the characteristics of stratified flow in the Bosphorus Strait and their relation to local and regional, short- and long-term changes in the meteorological parameters are studied by using the measurement data and the results are discussed comparatively.  相似文献   

Relationship between drought and solar irradiation variables     

Sevinc Sirdas  Ahmet Duran Sahin 《水文研究》2008,22(10):1460-1472

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Factors controlling the morphological evolution of the Çanakkale Strait (Dardanelles, Turkey)     

Erkan Gökaşan  Mustafa Ergin  Mustafa Özyalvaç  Halil İbrahim Sur  Hüseyin Tur  Tolga Görüm  Timur Ustaömer  Fatma Gül Batuk  Hakan Alp  Halim Birkan  Ahmet Türker  Erhan Gezgin  Murat Özturan 《Geo-Marine Letters》2008,28(2):107-129

Seismic profiling, bathymetric and physical oceanographic data collected from the Çanakkale Strait revealed that the morphological evolution of the strait has been controlled by tectonic activity, and sediment erosion and deposition. Sediments in the strait have been sourced mostly by rivers draining the Biga Peninsula during lowstand periods. In highstand periods, by contrast, deposits in the strait were reworked by currents. The seafloor morphology of the Çanakkale Strait is also controlled by a sequence of factors ranging from tectonics to current erosion and deposition. Channel deposits overlying the basement are being eroded at the narrower, meandering central section of the strait (the Nara Passage) due to high current velocities. The eroded sediments are deposited in the relatively linear and wider, northern and southern sectors of the strait exposed to low current velocities. As a result, the high-energy areas are more deeply incised due to the erosion, whereas deposition elevates the seafloor in the areas exposed to lower current energy. Three strike-slip faults, which possibly relate to the activity of the North Anatolian Fault Zone, are responsible for the irregular shape of the strait and this, in turn, controls the current velocity along the strait. The high-energy conditions probably commenced with the latest invasion of Mediterranean waters some 12 ka b.p., and have continued as a two-layered current system to the present day.  相似文献   

Vehicle effects on seismic response of a simple‐span bridge during shake tests          下载免费PDF全文

Nefize Shaban  Alp Caner  Ahmet Yakut  Aysegul Askan  Ali Karimzadeh Naghshineh  Arman Domanic  Gizem Can 《地震工程与结构动力学》2015,44(6):889-905

Presence of vehicles on a bridge has been observed many times during past earthquakes. Although in practice, the engineers may or may not include the live load contribution to seismic weight in design, current bridge design codes do not specify a certain guideline. A very limited research has been conducted to address this issue from design point of view. The focus of this research is to experimentally assess the effect of a vehicle on the seismic response of a bridge through a large‐scale model. In this scope, a 12‐meter long bridge, having a one lane deck with concrete slab on steel girders, has been shaken under five different ground motions obtained from recent earthquakes that occurred in Turkey, in its transverse direction, both with and without a vehicle on top of the deck. The measured results have indicated that top slab transverse acceleration and bearing displacements can reduce up to 18.7% in presence of a vehicle during seismic tests, which is an indication of reduction in substructure forces. The main reason for the reduction in seismic response of the bridge in the presence of live load can be ascribed to the increase in damping of the system due to mass damper‐like action induced by the vehicle. This beneficial effect cannot be observed in vertical seismic response. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

Possible worst-case tsunami scenarios around the Marmara Sea from combined earthquake and landslide sources     

Panon Latcharote  Anawat Suppasri  Fumihiko Imamura  Betul Aytore  Ahmet Cevdet Yalciner 《Pure and Applied Geophysics》2016,173(12):3823-3846

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Earthquakes,model systems and connections to <Emphasis Type="Italic">q</Emphasis>-statistics     

Ahmet Celikoglu  Ugur Tirnakli 《Acta Geophysica》2012,60(3):535-546

In this work, we make an attempt to review some of the recent studies on earthquakes using either real catalogs or synthetic data coming from some model systems. A common feature of all these works is the use of q-statistics as a tool.  相似文献   

Homotopy perturbation method for solving the space–time fractional advection–dispersion equation     

Ahmet Yıldırım  Hüseyin Koçak 《Advances in water resources》2009

In this paper we present a reliable algorithm, the homotopy perturbation method, to construct numerical solutions of the space–time fractional advection–dispersion equation in the form of a rapidly convergent series with easily computable components. Fractional advection–dispersion equations are used in groundwater hydrology to model the transport of passive tracers carried by fluid flow in a porous medium. The fractional derivatives are described in the Caputo sense. Some examples are given. Numerical results show that the homotopy perturbation method is easy to implement and accurate when applied to space–time fractional advection–dispersion equations.  相似文献   

Comparison of TRMM-based flood indices for Gaziantep,Turkey   总被引：1，自引：0，他引：1  

Senayi Dönmez  Ahmet Emre Tekeli 《Natural Hazards》2017,88(2):821-834

Floods are the most common natural disasters threatening the welfare of humanity. Gaziantep, a city located in a semi-arid region of Turkey, is occasionally flooded, and in May 2014, a flood not only caused property damage, but also resulted in the death of a lady who became trapped in flood waters. The fatality and property damage of flash floods arise from the limited response time for remediation. Despite improvements in numerical weather predictions, forecasting flash floods is not easy. Due to its frequent observations, Tropical Rainfall Measuring Mission (TRMM) Multi-Satellite Precipitation Analysis (TMPA) real-time (RT) 3B42RT data are tested for Gaziantep flood predictions in this study. During TRMM era, six floods occurred in Gaziantep. Three-hourly 3B42RT data covering the 2000- to 2014-year period indicated high rain rates during months in which floods were observed. Also daily variation of rainfall was well represented. High-intensity rain (HIR), cumulative distribution functions (CDF) and Gaziantep Flood Index (GAFI) indices are developed for flood characterization. HIR, calculated as 10 mm/h, detected October and December of 2010 floods. CDFs with 99, 98.5, 95 and 91.3% indicated 4 floods occurred in August 2005, June 2007, October 2010 and December 2010, respectively. GAFI was able to detect 4 out of 6 occurrences (August 2005, June 2007, October 2010 and December 2010) as values ranging from 1 to 2.63 are selected for monthly precipitation. In the missed occurrence, 3B42RT did not indicate any rainfall. Although only rain rates are used in flood characterization, the results are promising, and the simplicity of the methodology favors its usage. Also, methodology can easily be implemented to TRMM following missions such as Global Precipitation Measurement Mission.  相似文献   

Contents of Volume 29     

C. Emdad Haque  Dale Dominey-Howes  Nuray Karanci  Gerassimos Papadopoulos  Ahmet Yalciner 《Natural Hazards》2003,29(3):603-606

Volume Contents

Contents of Volume 29  相似文献   

Relationships Between Fundamental Seismic Hazard Parameters for the Different Source Regions in Turkey     

Yusuf?BayrakEmail author  Ahmet?Yilmaztürk  Serkan??ztürk 《Natural Hazards》2005,36(3):445-462

Turkey has been divided into eight different seismic regions taking into consideration the tectonic environments and epicenters of the earthquakes to examine relationships of the modal values (a/b), the expected maximum magnitudes (M_max) and the maximum intensities (I_max). For this purpose, the earthquakes for the time period 1900–1992 from the Global Hypocenter Data Base CD-ROM prepared by USGS, and for the time period 1993–2001 from the PDE data and IRIS data are used. Concerning the relationships developed between different magnitude scales and between surface wave magnitudes (M_S) and intensity for different source regions in Turkey, we have constructed a uniform catalog of M_S. We have estimated the values of M_max and I_max using the Gumbel III asymptotic distribution. Highest a-values are observed in the Aegean region and the lowest b-values are estimated for the North Anatolian Fault. Maximum values of a/b, M_max and I_max are related to the eastern and western part of the North Anatolian Fault and the Aegean Arc. The lowest values of all parameters are observed near the Mid Anatolian Fault system. Linear relationships have been calculated between a/b, M_max and I_max using orthogonal regression. If one of the three parameters is computed, two other parameters can be calculated empirically using these linear relationships. Hazard maps of M_max and I_max values are produced using these relationships for a grid of equally spaced points at 1°. It is observed that the maps produced empirically may be used as a measure of seismic hazard in Turkey.  相似文献