OBC signal fidelity

A suite of three tests was performed to characterize the signal fidelity of OBC 4C acquisition systems. The test methodology was to evaluate individual sensor stations by acquiring source lines that were parallel to the in‐line and cross‐line horizontal sensors and source lines that were at 45° to the in‐line and cross‐line sensors. This technique provides constant azimuth gathers with a uniform offset range and removes issues associated with source array directivity. Characterization of the test data identified the frequency content of the geophone signals and the correlation between the vertical and cross‐line geophones as the most sensitive indicators of signal infidelity. In the former case, stations with questionable signal fidelity exhibited a very reverberatory signal. This signal was most evident on the cross‐line sensor. In the latter case, when normalized cross‐correlation coefficients are computed in a moving window, the cross‐line sensor and the vertical sensor are highly correlated, beginning several hundred milliseconds after the first arrivals. These characteristics can be exploited to allow stations with questionable signal fidelity to be programmatically identified. One means of identifying questionable stations is to compute the histogram of the instantaneous frequency. The frequency distributions from questionable stations are unambiguously distinguishable from stations that exhibit better signal fidelity. It was noted that signal fidelity appeared as a range, between acceptable and poor. To characterize the signal fidelity of an acquisition system adequately, the number of test samples must be statistically significant.     

First Ground-Based Photometry and Light Curve Analysis of the Recently Discovered Contact Binary Hx Uma

Photoelectric UBV light curves of the recently discovered eclipsing binary HX UMa were obtained and studied to determine the preliminary physical parameters of the system for the first time. The observations were taken at the TüBİTAK¹ – Turkish National Observatory (TUG) on three nights in April 2003. A simultaneous analysis of the light and radial velocity curves yields a typical A-type contact binary with a high degree of overcontact. The influence of the close visual companion to the total light of the system was taken into account during the analysis. ¹TüBİTAK: The Scientific and Technical Research Council of Turkey.     

The role of hydrogeology in solution-subsidence development and its environmental impacts; a case-study for Sazlıca (Niğde, Turkey)

Solution-subsidence and other types of collapse failures developed in the vicinity of Sazlıca have been a major source of environmental problems such as groundwater pollution, soil erosion, and foundation failures. Extensive pumping of water from the Lake Dipsiz during irrigation seasons creates landslide developments at the shores of the lake. Five stages of landslide development were observed in the unconsolidated soils around Lake Dipsiz. Bowl-shaped solution-subsidence features with depths from 1 to 3 m and diameters between 1 and 60 m were formed due to excess pumping, and recharge and discharge features of unconfined aquifer. The pumping activities must be controlled to prevent further environmental problems. Lake Dipsiz and other subsidence developments are the groundwater exposure areas highly vulnerable to contamination. The proposed remedies for overcoming the environmental problems are the establishment of conservation areas around such natural features; ceasing the removal of top soil, controlling the urbanization, and keeping the livestock farming away from the areas susceptible to pollution. Received: 2 June 1997 · Accepted: 16 January 1998     

The links between the categorised Southern Oscillation indicators and climate and hydrologic variables in Turkey

Some previous global and regional studies have indicated teleconnection between the extreme phases of the Southern Oscillation (SO) and Turkish climate and hydrologic variables; however, they failed to suggest a strong correlation structure. In this study, categorised Southern Oscillation index (SOI) and Multivariate ENSO (El Nino Southern Oscillation) index (MEI) series were used to examine the far‐reaching effects of the SO on temperature, precipitation and streamflow patterns in Turkey. These SO indicators were categorised into five subgroups according to their empirical distributions. Correlations between the categorised SO indicators and three analysis variables were computed using the Spearman's rho from lag‐0 to lag‐4. Significance of calculated correlations was tested at the 0·01 level for station‐based analysis and at the 0·05 level for regional analysis. Temperature records demonstrated significant correlations with the categorised SOI and MEI in nearly half of the entire stations. For some categories, precipitation and streamflow were found to be correlated with the SO indicators in some stations mainly in western Turkey. Regional analyses of temperature and precipitation revealed a clear and strong correlation structure with the categorised SO indicators on a large portion of Turkey. This was not concluded by the earlier pertinent studies. Besides, this study showed that significant correlations were obtained not only for the SO extreme phases (namely, El Nino and La Nina) but also for neutral and moderate phases of the SO. Plausible explanations for the observed teleconnection are presented. Copyright © 2009 John Wiley & Sons, Ltd.     

Digital Identification of Ecosystem Structure in the F?rt?na Valley of the Ka?kar Mountains in the Rize City of Turkey

Identifying the structure of protected mountain ecosystems is an important task for understanding conservation sustainability. The study area, the F？rt？na Valley, located in the Rize City on the Eastern Blacksea Coast, is one of the biological hotspots and a National Park of Turkey. In order to identify the structure of mountain ecosystems, we generated a GIS database for the main environmental parameters of the study area, including elevation, slope and aspect layers for topographic structure, 10 year mean values of Normalized Difference Vegetation Index（NDVI）, data for vegetation structure, annual mean temperature and precipitation layers for climatic structure, main soil groups for soil structure and stream flow accumulation, stream flow length and stream order layers for hydrological structure .To identify the complex relations among environmental factors in the study area a data reduction method is applied with Principal Component Analysis （PCA）. PCA is performed using data of 16 layers from Geographical Information Systems （GIS）. PCA analysis reduced 16 dimensions into 5 dimensions containing 75% of the variation in all data. It is also revealed that the topographic structure, mainly altitude, dominates the ecosystems of the F？rt？na Valley, but it should be considered that the interactions of environmental factors in an ecosystem dynamics are very complex. The ecosystem structure is determined by the environmental factors direct or indirect effects on energy regulation of an ecosystem. Therefore the relationship between topographic elements and other abiotic-biotic elements in the Fcrtcna Valley are important for environmental assessment and sustainability of a protected area, and these effects are explained in this study.     

Finger prints of the formation of geothermal springs on the granitoids: Beypazarı–Ankara, Turkey

The Beypazarı granitoid in central Anatolia was emplaced during the Late Cretaceous and it is partly covered with Early Miocene–Quaternary sedimentary and volcanic units. Compression and tension regimes of the Beypazarı granitoid emplacing along the Sakarya River were evaluated considering the kinematical characteristics of discontinuities on granitoids, petrographic/geochemical works, formation of geothermal spring and irregularities in topographic structure. It was determined that the Beypazarı granitoid was witnessed with NE–SW compressional stress and NW–SE extensional stress which resulted in the formation of the Kapullu normal fault with N55–72°E, 78°SE crossing the Kapullu spring site. There are also several other probable normal faults around this fault in the Sakarya River basin. The results of the geochemical studies reveal that SiO₂, Na₂O, Al₂O_3, CaO and K₂O as a major oxide and As, Rb, Sr, Th and U as trace elements are decreased away from the Kapullu bath spring. On the other hand, the ratio of Fe₂O₃ and MgO as major oxide and Y as a trace element with the lost on ignition (LOI) are increased away from the Kapullu fault. Regard as the regional plate tectonism, there is a consistency between the direction of compression in the Beypazarı granitoid and that developed by the southwesterly movement of the Anatolian plate.     

Adaptive neuro-fuzzy evaluation of wind farm power production as function of wind speed and direction

Wind velocity assumes a critical part for measuring the power created by the wind turbines. Nonetheless, power production from wind has a few weaknesses. One significant issue is that wind is a discontinuous energy source which implies that there exists substantial variability in the generation of vigor because of different variables, for example, wind speed. Wind direction is a significant variable for proficient turbine control for getting the most energy with a given wind speed. Taking into account the conjectures on wind heading, it might be conceivable to adjust the turbine to the wind bearing to get the most energy yield. Since both forecasts of wind speed and direction are basic for effective wind energy collecting it is crucial to develop a methodology for estimation of wind speed and direction and afterwards to estimate wind farm power production as function of wind pace and heading distribution. Despite the fact that various numerical functions have been proposed for demonstrating the wind speed and direction frequency distribution, there are still disadvantages of the models like very demanding in terms of calculation time. In this investigation adaptive neuro-fuzzy inference system (ANFIS), which is a particular sort of the artificial neural networks (ANN) family, was used to anticipate the wind speed and direction frequency dispersion. Thereafter, the ANFIS system was utilized to gauge wind homestead power creation as function of wind velocity and bearing. Neural system in ANFIS modifies parameters of enrollment capacity in the fuzzy logic of the fuzzy inference system. The reenactment outcomes exhibited in this paper demonstrate the adequacy of the created technique.