Modeling of trophospheric ozone concentrations using genetically trained multi-level cellular neural networks     

H. Kurtulus OZCAN  Erdem BILGILI  Ulku SAHIN  O. Nuri UCAN  Cuma BAYAT 《大气科学进展》2007,24(5):907-914

Tropospheric ozone concentrations, which are an important air pollutant, are modeled by the use of an artificial intelligence structure. Data obtained from air pollution measurement stations in the city of Istanbul are utilized in constituting the model. A supervised algorithm for the evaluation of ozone concentration using a genetically trained multi-level cellular neural network （ML-CNN） is introduced, developed, and applied to real data. A genetic algorithm is used in the optimization of CNN templates. The model results and the actual measurement results are compared and statistically evaluated. It is observed that seasonal changes in ozone concentrations are reflected effectively by the concentrations estimated by the multilevel-CNN model structure, with a correlation value of 0.57 ascertained between actual and model results. It is shown that the multilevel-CNN modeling technique is as satisfactory as other modeling techniques in associating the data in a complex medium in air pollution applications.  相似文献   

Identification of aquifer and well parameters from step-drawdown tests     

Cem B. Avci  Emin Ciftci  A. Ufuk Sahin 《Hydrogeology Journal》2010,18(7):1591-1601

A new analysis technique has been proposed for interpreting transient step-drawdown test data. The proposed method is based on taking the derivative of the drawdown with respect to time for the entire pumping test period to eliminate the time-independent well-loss terms. The derivative function is subsequently integrated to obtain the time-dependent aquifer drawdown as a continuous function. The well-loss parameters are then obtained with higher accuracy once the aquifer behavior is identified. The proposed method is applicable for analyzing data obtained not only from ideal confined aquifers but also from other aquifer types (i.e. unconfined) and non-ideal aquifers (i.e. heterogeneous). The technique was tested for synthetically generated and field data; the proposed approach was noted to provide accurate aquifer and well-loss parameter estimates. The results of the proposed method were compared with those of some of the existing methods for analyzing step-drawdown test data and were found to be more reliable and robust.  相似文献   

Case study of PM pollution in playgrounds in Istanbul     

Huseyin Ozdemir  Bulent Mertoglu  Goksel Demir  Ali Deniz  Hüseyin Toros 《Theoretical and Applied Climatology》2012,108(3-4):553-562

In a world where at least 50% of the population is living in urban environments, air pollution and specifically particulate matter (PM) have become one of the most critical issues for human health. Children are more susceptible than adults to air pollution and its adverse effects because they inhale and retain larger amounts of air pollutants per unit of body weight. In this study, PM pollution, particularly PM₁₀ and PM_2.5, at selected playgrounds were investigated in Istanbul city. Istanbul is a megacity of over 15 million inhabitants, and on-road traffic is increasing rapidly (over 3 million vehicles on the road). To estimate the effect of traffic emissions on children, the location of the playgrounds were selected according to traffic density. Measurements were carried out at five different playgrounds throughout the city in 2009. Field results show that the values of PM₁₀ and PM_2.5 have reached critical limits at the playgrounds close to the main roads, especially at P-1. Thus, we focused on this location and investigated a source other than traffic emissions. One of the episode days has been observed on 5–7 March 2009. Evaluations of meteorological events are very important to determine air pollution sources and their long-range transport. Therefore, the Weather Research and Forecasting model (WRF) was used to simulate and forecast meteorological parameters and the hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) applied to investigate long-range transport. According to the WRF model outputs, there was a low-pressure system over Geneva gulf on the 500-hPa level, and its core had been located over Britain on 5 March 2009 00UTC. The system had been sweeping dust from the Sahara Desert and carrying the air particles over Istanbul. Similarly, backward HYSPLIT analysis showed that air particles had moved through Istanbul from Northern Africa.  相似文献   

Evaluation of morphometric parameters of drainage networks derived from topographic maps and DEM in point of floods   总被引：4，自引：0，他引：4  

Hasan Ozdemir  Deanne Bird 《Environmental Geology》2009,56(7):1405-1415

An evaluation of morphometric parameters of two drainage networks derived from different sources was done to determine the influence of sub-basins to flooding on the main channel in the Havran River basin (Balıkesir-Turkey). Drainage networks for the sub-basins were derived from both topographic maps scaled 1:25.000 and a 10-m resolution digital elevation model (DEM) using geographic information systems (GIS). Blue lines, representing fluvial channels on the topographic maps were accepted as a drainage network, which does not depict all exterior links in the basin. The second drainage network was extracted from the DEM using minimum accumulation area threshold to include all exterior links. Morphometric parameters were applied to the two types of drainage networks at sub-basin levels. These parameters were used to assess the influence of the sub-basins on the main channel with respect to flooding. The results show that the drainage network of sub-basin 4—where a dam was constructed on its outlet to mitigate potential floods—has a lower influence morphometrically to produce probable floods on the main channel than that of sub-basins 1, 3, and 5. The construction of the dam will help reduce flooding on the main channel from sub-basin 4 but it will not prevent potential flooding from sub-basin 1, 3 and 5, which join the main channel downstream of sub-basin 4. Therefore, flood mitigation efforts should be considered in order to protect the settlement and agricultural lands on the floodplain downstream of the dam. In order to increase our understanding of flood hazards, and to determine appropriate mitigation solutions, drainage morphometry research should be included as an essential component to hydrologic studies.  相似文献   

Coastal vulnerability to sea-level rise: a spatial–temporal assessment framework     

Oz Sahin  Sherif Mohamed 《Natural Hazards》2014,70(1):395-414

The scientific community is confident that warming of the Earth’s climate is unequivocal. Sea-level rise, which poses potential threats to coastal areas, is one of the most recognised possible impacts of this climate change. The nonlinearities, complexities, and spatial and temporal lags are common characteristics of coastal processes driven by human and natural interaction. With the acknowledgement of the complexity and dynamic nature of coastal systems, this paper introduces a spatial–temporal assessment framework, for addressing both the temporal and spatial variations, when assessing the vulnerability of natural and human systems in coastal areas. The framework is based upon a combination of system dynamics (SD) modelling and geographical information systems by taking into account spatial (x, y, z) and temporal (t) dimensions. The strategy of the adopted approach is to use the loose coupling approach by which a spatial model component is incorporated into a SD model component through a data converter.  相似文献   

Asteroseismology of the β Cephei star 12 (DD) Lacertae: photometric observations, pulsational frequency analysis and mode identification     

G. Handler  M. Jerzykiewicz  E. Rodríguez  K. Uytterhoeven  P. J. Amado  T. N. Dorokhova  N. I. Dorokhov  E. Poretti  J.-P. Sareyan  L. Parrao  D. Lorenz  D. Zsuffa  R. Drummond  J. Daszy&#;ska-Daszkiewicz  T. Verhoelst  J. De Ridder  B. Acke  P.-O. Bourge  A. I. Movchan  R. Garrido  M. Paparó  T. Sahin  V. Antoci  S. N. Udovichenko  K. Csorba  R. Crowe  B. Berkey  S. Stewart  D. Terry  D. E. Mkrtichian  C. Aerts 《Monthly notices of the Royal Astronomical Society》2006,365(1):327-338

  相似文献   

The SFXC software correlator for very long baseline interferometry: algorithms and implementation     

A. Keimpema  M. M. Kettenis  S. V. Pogrebenko  R. M. Campbell  G. Cimó  D. A. Duev  B. Eldering  N. Kruithof  H. J. van Langevelde  D. Marchal  G. Molera Calvés  H. Ozdemir  Z. Paragi  Y. Pidopryhora  A. Szomoru  J. Yang 《Experimental Astronomy》2015,39(2):259-279

  相似文献   

Lg Wave Attenuation in the Isparta Angle and Anatolian Plateau (Turkey)     

Sakir Sahin  Xueyang Bao  Niyazi Turkelli  Eric Sandvol  Ugur Teoman  Metin Kahraman 《Pure and Applied Geophysics》2013,170(3):337-351

We estimate Lg wave attenuation using local and regional seismic phases in the Isparta Angle and the Anatolian Plateau (Turkey). The Isparta Angle (IA) is a tectonically active zone forming the boundary between the African Plate and the Anatolian Plateau, and is currently undergoing N–S extensional deformation. The Anatolian Plateau contains many intra-continental faults including the North Anatolian Fault Zone and the East Anatolian Fault Zone as well as the Menderes Massif. A large waveform data set was compiled from a variety of local and regional seismic networks including 121 digital seismic stations (broad-band and short period) between 1999 and 2008 spanning the IA, the Anatolian Plateau and Azerbaijan. The data set was used to determine the nature of Lg wave propagation and characterize the nature of seismic attenuation within the crust of these regions. Lg waveforms were used to calculate the frequency-dependent Lg-Q _o and Lg- $ \eta $ . A wide range of Lg-Q _o values was obtained between ~52 ± 6 and 524 ± 227. Low Lg-Q _o values (~90–155) are calculated towards the north of IA, Iskenderun Gulf and its vicinity, Bingöl-Karl?ova, Izmit and its vicinity. Lg-Q _o values are especially low (<90) along the Menderes Massif and the Aksehir-Simav Fault Zones. This may be due to intrinsic attenuation of Lg associated with the partially molten crust and young volcanism. The high Lg-Q _o values (~350) are probably caused by the crust not being subject to large amounts of extensional deformation like the Antalya Gulf and apparently being thick enough to support Lg propagation. Relatively higher values along the border of this subduction zone and plate boundary might be related to the Taurus Mountain belts and Bitlis-Zagros Suture Zone. The lateral frequency dependency Lg- $ \eta $ is also consistent with high tectonic activity in this region.  相似文献   

Adsorption of carbonate and bicarbonate salts at the air–brine interface     

Orhan Ozdemir  Stoyan I. Karakashev  Anh V. Nguyen  Jan D. Miller 《International Journal of Mineral Processing》2006

Previous research has shown that the flotation of soluble salt is determined by interfacial water structure, thermal stability, and viscosity. These salts include alkali halide and alkali oxyanion salts. Of particular interest are the carbonate salts such as those associated with the great trona deposit of the Green River basin in Wyoming. In this study, we investigated the adsorption of carbonate and bicarbonate salts at the air–brine interface and correlated the adsorption behavior with water structure. Specifically, the equilibrium and dynamic surface tensions of sodium carbonate and sodium bicarbonate salts have been measured as a function of the salt concentration up to saturation and compared with the model prediction using the Gibbs–Langmuir adsorption theory. The results show that the negative adsorption of sodium carbonate leads to a significant increase in surface tension of the brine solution. For sodium bicarbonate, both the negative adsorption and the increase in surface tension are significantly lower when compared with the sodium carbonate case. The negative adsorption is correlated with the water structure making/breaking character of carbonate and bicarbonate solutions. In particular, sodium ions are significantly more hydrated than carbonate and bicarbonate ions, and, therefore, tend to be excluded from the air–brine interface. On the other hand, carbonate and bicarbonate ions are accommodated at the air–brine interface. In any event, the balance between sodium exclusion and carbonate/bicarbonate accommodation results in an increase in the surface tension of these solutions with an increase in salt concentration.  相似文献   

Investigation of automatic feature weighting methods (Fisher,Chi-square and Relief-F) for landslide susceptibility mapping     

Emrehan Kutlug Sahin  Cengizhan Ipbuker 《国际地球制图》2017,32(9):956-977

In landslide susceptibility mapping, factor weights have been usually determined by expert judgements. A novel methodology for weighting landslide causative factors by integrating statistical feature weighting algorithms was proposed. The primary focus of this study is to investigate the effectiveness of automatic feature weighting algorithms, namely Fisher, Chi-square and Relief-F algorithms. Analytic hierarchy process (AHP) method was used as a benchmark method to compare the performances of the weighting algorithms. All weighted factors were tested using factor-weighted overlay method, and quality of these maps was assessed using overall accuracy, area under the ROC curve (AUC) and success rate curve. In addition, Wilcoxon’s signed-rank test was applied to evaluate statistical differences between both estimated overall accuracies and AUCs, respectively. Results showed that the weights determined by feature weighting methods outperformed the conventional AHP method by about 6% and this level of differences was found to be statistically significant.  相似文献