Neural network and wavelet conjunction model for modelling monthly level fluctuations in Turkey

This paper proposes the application of a conjunction model (neuro‐wavelet) for forecasting monthly lake levels. The neuro‐wavelet (NW) conjunction model is improved combining two methods, discrete wavelet transform and artificial neural networks. The application of the methodology is presented for the Lake Van, which is the biggest lake in Turkey, and Lake Egirdir. The accuracy of the NW model is investigated for 1‐ and 6‐month‐ahead lake level forecasting. The root mean square errors, mean absolute relative errors and determination coefficient statistics are used for evaluating the accuracy of NW models. The results of the proposed models are compared with those of the neural networks. In the 1‐month‐ahead lake level forecasting, the NW conjunction model reduced the root mean square errors and mean absolute relative errors by 87–34% and 86–31% for the Van and Egirdir lakes, respectively. In the 6‐month‐ahead lake level forecasting, the NW conjunction model reduced the root mean square errors and mean absolute relative errors by 34–48% and 30‐46% for the Van and Egirdir lakes, respectively. The comparison results indicate that the suggested model could significantly increase the short‐ and long‐term forecast accuracy. Copyright © 2009 John Wiley & Sons, Ltd.     

North-South asymmetry in the solar flare index

This paper reports the results of a study of the N-S asymmetry in the flare index using the results of Knoka (1985) combined with our results for the solar cycles 17 to the current cycle 22. By comparing the time-variation of the asymmetry curve with the solar activity variation of the 11-year cycle, we have found that the flare index asymmetry curve is not in phase with the solar cycle and that the asymmetry peaks during solar minimum. A periodic behaviour in the N-S asymmetry appears: the activity in one hemisphere is more important during the ascending part of the cycle whereas during the descending part the activity becomes more important in the other hemisphere. The dominance of flare activity in the southern hemisphere continues during cycle 22 and, according to our findings, this dominance will increase gradually during the following cycle 23.     

Local galactic evolution

The evolution of the Solar neighbourhood is followed using a unique, magnitude complete and kinematically unbiased sample of 14,000 F, G, and K dwarfs. Metallicity, age, space motion and galactic orbits have been determined for all stars. The result is a detailed view of the complex evolution of the local Milky Way, which must be matched by any model for the chemical and dynamical evolution of the Galactic disk. E.g., such models must explain the shape and large scatter in the age-metallity relation as well as the overall metallicity distribution; the evolution of stellar kinematics with age; the distribution of stars in velocity space; and the contributions from the thick and thin disks to all these relations. This revised version was published online in August 2006 with corrections to the Cover Date.     

Fluid inclusion and sulfur isotope thermometry of the Inkaya (Simav-Kütahya) Cu-Pb-Zn-(Ag) mineralization, NW TURKEY

The Inkaya Cu-Pb-Zn-(Ag) mineralization, located about 20 km west of the Simav (Kütahya-Turkey), is situated in the northern part of the Menderes Massif Metamorphics. The mineralization is located along an E-W trending fault in the Cambrian Simav metamorphics consisting of quartz-muscovite schist, quartz-biotite schist, muscovite schist, biotite schist and the Ar?kayas? formation composed of marbles. Mineralized veins are 30–35 cm in width. The primary mineralization is represented by abundant galena, sphalerite, chalcopyrite, pyrite, fahlore and minor amounts of cerussite, anglesite, digenite, enargite, chalcocite, covellite, bornite, limonite, hematite and goethite with gangue quartz. Fluid inclusion studies on the quartz samples collected from the mineralized veins indicate that the temperature range of the fluids is 235°C to 340°C and the salinities are 0.7 to 4.49 wt. % NaCl equivalent. The wide range of homogenization temperatures indicates that two different fluid generations were trapped in quartz. Sulfur isotope studies of the sulfide minerals showed that all of the δ ³⁴S values are between ?2.1 and 2.6 per mil. These values are a typical range for hydrothermal sulfide minerals that have sulfur derived from a magmatic source. Pyrite-galena and pyrite-chalcopyrite sulfur isotope fractionation is consistent with an approach to isotopic equilibrium, and calculated temperatures are 254.6 and 277.4°C for pyrite-galena and 274.7°C for pyrite-chalcopyrite. The microthermometric data and sulfur isotope thermometry indicate the existence of a hydrothermal fluid that circulated along the fault crossing the Simav metamorphics and Ar?kayas? formation. Fluid inclusion and sulfur isotope thermometry can be used in combination with ore petrographical and geological information to provide site-specific targets for meso-hypothermal metal concentrations.     

Late Pleistocene and Holocene cool‐water carbonates of the Western Mediterranean Sea

Post‐glacial, neritic cool‐water carbonates of the Western Mediterranean Sea were examined by means of hydroacoustic data, sediment surface sampling and vibrocoring to unravel geometries and to reconstruct sedimentary evolution in response to the last sea‐level rise. The analysed areas, located on the Alboran Ridge, in the Bay of Oran, and at the southern shelf of the island of Mallorca, are microtidal and bathed by oligotrophic to weakly mesotrophic waters. Seasonal water temperature varies between 13 °C and 27 °C. Echosounder profiles show that the Bay of Oran and the southern shelf of Mallorca are distally steepened ramps, while the Alboran Ridge forms a steep‐flanked rugged plateau around the Alboran Island. In the three areas, an up to 10 m thick post‐glacial sediment cover overlies an unconformity. In Oran and Mallorca, stacked lowstand wedges occur in water depths of 120 to 130 m. On the Alboran Ridge and in the Bay of Oran, highstand wedges occur at 35 to 40 m. Up to 5 m long cores of upper Pleistocene to Holocene successions were recovered in water depths between 40 and 81 m. Deposits contain more than 80% carbonate, with mixed carbonate‐volcaniclastics in the lower part of some cores in Alboran. The carbonates consist of up to 53% of aragonite and up to 83% of high magnesium calcite. Radiocarbon dating of bivalve shells, coralline algae and serpulid tubes indicates that deposits are as old as 12 400 cal yr bp . The carbonate factories in the three areas are dominated mostly by red algae, but some intervals in the cores are richer in bivalves. A facies rich in the gastropod Turritella, reflecting elevated surface productivity, is restricted to the Mallorca Shelf. Rhodoliths occur at the sediment surface in most areas at water depths shallower than 70 m; they form a 10 to 20 cm thick veneer overlying rhodolith‐poor bioclastic sediments which, nonetheless, contain abundant red algal debris. This rhodolith layer has been developing for the past 800 to 1000 years. Similar layers at different positions in the cores are interpreted as reflecting in situ growth of rhodoliths at times of reduced net sedimentation. Sedimentary successions in the cores record the post‐glacial sea‐level rise and the degree of sediment exposure to bottom currents. Deepening‐upward trends in the successions are either reflected by shallow to deep facies transitions or by a corresponding change of depth‐indicative red algae. There are only weak downcore variations of carbonate mineralogy, which indicate that no dissolution or high magnesium to low magnesium calcite neomorphism occurs in the shallow subsurface. These new data support the approach of using the Recent facies distribution for interpretation of past cool‐water, low‐energy, microtidal carbonate depositional systems. Hydroacoustic data show that previous Pleistocene transgressive and highstand inner ramp deposits and wedges were removed during sea‐level lowstands and accumulated downslope as stacked lowstand wedges; this suggests that, under conditions of high‐amplitude sea‐level fluctuations, the stratigraphic record of similar cool‐water carbonates may be biased.     

An integrated earthquake vulnerability assessment framework for urban areas

In this paper, an integrated urban earthquake vulnerability assessment framework, which considers vulnerability of urban environment in a holistic manner and performs the vulnerability assessment for the neighborhood scale, is proposed. The main motivation behind this approach is the inability to implement existing vulnerability assessment methodologies for countries like Turkey, where the required data are usually missing or inadequate for the decision-makers in prioritization their limited resources for risk reduction in the administrative units from which they are responsible for. The methodology integrates socio-economical, structural, coastal, ground condition, vulnerabilities (fragilities), as well as accessibility to critical services. The proposed methodology is implemented for Eskisehir, which is one of the metropolitans of Turkey. In the implementation of the proposed framework, geographic information system (GIS) is used. While the overall vulnerabilities obtained for neighborhoods are mapped in GIS, the overall vulnerabilities obtained for buildings are visualized in 3D city model. The main reason behind using different mapping and visualization tools for vulnerabilities is to provide better ways for communicating with decision-makers. The implementation of the proposed vulnerability assessment methodology indicates that an urban area may have different vulnerability patterns in terms of structural, socio-economical, and accessibility to critical services. When such patterns are investigated, effective vulnerability reduction policies can be designed by the decision-makers. The proposed methodology well serves for this purpose.     

Resolution dependent relative dispersion statistics in a hierarchy of ocean models

In order to determine the effect of Eulerian spatial resolution on the two particle statistics of synthetic drifter trajectories, we examine a hierarchy of ocean models, starting from 2D turbulence simulations, progressing to idealized simulations of a buoyant coastal jet with ROMS, and finally to realistic HYCOM simulations of the Gulf Stream. In each case, particle dispersion at large time and space scales is found to be controlled by energetic meso-scale features of the flow that are relatively insensitive to the resolution of finer scale motions. In all cases, time-distance graphs given in terms of computed Finite Scale Lyapunov Exponents show an expected increase in the extent of exponential scaling with increasing spatial smoothing of the velocity field. The limiting value of the FSLE at small separation distances is found to scale remarkably well with the resolution of Eulerian velocity gradients as given by the average of positive Okubo–Weiss parameter values.     

Lime Stabilization of Soils Underlying a Salt Evaporation Pond: A Laboratory Study

The purpose of this article is to investigate a possible use of lime for the stabilization of base soils underlying salt evaporation ponds in Çamalt? Solar Marine Salt Plant. The plant is located on the old Gediz River Delta, on the north shore of the Izmir Bay-Turkey, where alluvial deltaic soft marine sediments constitute the local soil condition. The low bearing capacity of the pond base soils results in some problems on the mechanical harvest of the solar salt. Therefore, stabilization was taken into consideration for improving the productivity of the salt plant. For this purpose, bench-scale laboratory tests were performed on the specimens that had been sampled from the bases of the salt evaporation pond to investigate the influence of lime on the unconfined compressive strength (UCS) of these marine sediments. By interpreting the pH test results and consistency limits of the lime stabilized soils, optimum lime content was determined as 8%. The verification of the long-term pozzolanic reactions for the optimum lime content was conducted by performing UCS tests with up to six months curing periods, along with the microstructural analysis through X-ray diffraction analysis (XRD) and a scanning electron microscope (SEM). Long-term tests revealed that the optimum lime content successfully sustained the required pozzolanic reactions, and a strength gain of 500% was achieved for a six-month curing period.