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101.
In this study, two different historical structures built in Trabzon have been processed by ambient vibrations and seismic refraction measurements. One of the investigated historical structures is the Atatürk Pavilion built in the nineteenth century, and the other one is Hagia Sophia which was built in the thirteenth century. These two buildings are among the most important historical buildings in Trabzon and are very important for the tourism of the city. In order to determine peak/s frequency and amplitude from the horizontal-to-vertical spectral ratios (HVSRs), we have performed several measurements of ambient vibrations both inside (at different floors) and outside (on the ground) of structures. We have also conducted seismic prospecting to evaluate the vertical 1D and 2D profile of longitudinal and shear seismic waves, Vp and Vs, respectively. To this purpose, we have performed seismic refraction tomography and MASW. Ambient vibrations and seismic measurements were compared with each other. The results show that average predominant frequencies and HVSR amplitudes of inside and outside of Atatürk Pavilion are 4.0 Hz, 7.8 Hz and 2.6, 2.3, respectively. The Vp values vary from 300 to 2070 m/s, and the Vs for maximum effective depth is up to 790 m/s in Atatürk Pavilion. On the other hand, average predominant frequencies and HVSR amplitudes of inside and outside of Hagia Sophia and its tower are 4.7, 4.4 and 2.4 Hz and 1.6, 1.8 and 6.9, respectively. Vp values range from 450 to 2200 m/s, and Vs for maximum effective depth is also up to 1000 m/s in Hagia Sophia. The frequency values (F0?=?Vs/4 h) calculated from the velocities up to the maximum effective depth for Atatürk Pavilion are in good agreement with the predominant frequency values determined from ambient vibrations. Atatürk Pavilion and Hagia Sophia soils have been classed according to Eurocode 8 by using VS30 values. The class was defined as “B.” Moreover, the bedrock in studied area is basalt. The high Vp and Vs values are also compatible with the lithology. The HVSR curves measured at the Hagia Sophia show the presence of clear peaks when compared to the Atatürk Pavilion. At the same time, there are marked velocity changes in the Vs sections calculated in both areas. As a result, in both areas there are significant impedance contrasts in the subsoil. However, this impedance contrast is more evident in Hagia Sophia. This could be also compatible with a lithological transition. The possible soil–structure interaction was investigated by using all the results and evaluated in terms of resonance risk. It is thought that the probability of resonance risk at Atatürk Pavilion is low according to the ambient vibrations measurements. However, resonance risk should be taken into consideration at Hagia Sophia site since the predominant frequency values are very close to each other. Finally, this site should be investigated in detail and necessary precautions should be taken against the risk of resonance. 相似文献
102.
S. O. Selam E. M. Esmer H. V. Şenavcı E. Bahar O. Yörükoğlu M. Yılmaz Ö. Baştürk 《Astrophysics and Space Science》2018,363(2):34
In this study, we have performed simultaneous solutions of light and radial velocity curves of two eclipsing binary systems, V566 Oph and V972 Her. We observed both systems spectroscopically with a very recently installed spectrograph on the 40 cm telescope, T40, located in Ankara University Kreiken Observatory (AUKR), for the first time. We made use of the photometric data from the Hipparcos satellite for V972 Her, while we obtained the photometric observations of V566 Oph by using the 35 cm telescope, T35, located also in our observatory campus. We derived the absolute parameters for both systems and discussed their evolutionary states. In addition to the simultaneous analysis, we have also analyzed the change in mid-eclipse times for V566 Oph, and found cyclic variations, for which we have discussed light-time effect and magnetic activity as their potential origin, superimposed on a secular change due to a mass transfer between the components of the binary. 相似文献
103.
Federico M. Ledesma Silvina Van der Molen Pedro J. Barón 《Journal of Sea Research》2010,63(3-4):213-216
The European green crab Carcinus maenas is a widely spread invasive species. Studying the most recently introduced population of the species in the Atlantic coast off Patagonia, it became apparent to us that carapaces (the dorsal cover of the visceral-cavity detaching from the rest of the exoskeleton after ecdysis) accumulated on the intertidal may be used as a valuable complementary material to analyze the size structure of crabs. However, since growth rate (and consequently size at instar) of crabs differs between males and females, finding a method to distinguish crab sex by observation of carapace morphology was necessary to allow the construction of independent size frequency distributions for each sex. In this work, we examined the shape of the carapaces from both sexes of C. maenas, and using Elliptical Fourier Analysis successfully identified sexual dimorphism. Thus, a reliable method to identify sexes by visual observation of the carapace was developed. Based on our results, we discuss the evolutionary significance of carapace form differentiation of both sexes. 相似文献
104.
In this paper, the shear strength with respect to the matric suction of unsaturated soils was studied. For this purpose, unsaturated
triaxial testing procedures were applied to the undisturbed residual soil specimens. An apparatus for performing triaxial
tests was designed and constructed. In the tests, matric suction was controlled by using the axis translation technique, and
pore water volume changes were measured by means of a volume change transducer with 10−8 m3 sensitivity. The test results indicated that the matric suction contributes to the shear strength of unsaturated soil specimens,
and this contribution called suction strength varies non-linearly with respect to the matric suction. The logarithmic model
needing to know the air-entry value and the internal friction angle of a soil specimen for prediction of the suction strength
were presented and compared with the test results. It was found that suction strength values predicted from the proposed model
were in satisfactory agreement with the experimental results. 相似文献
105.
A field application for lime stabilization 总被引:2,自引:0,他引:2
This study presents the improvements achieved as a result of the lime stabilization application conducted by the joint effort of the Turkish Association of Lime Industrialists and the General Directorate of Rural Services on the 200 m long section of the Ankara Province Yukar? Yurtçu Village road where green and brown clays are dominant. The study also numerically demonstrates the impacts of these improvements on the road section based on the results of various laboratory and field tests. The lime stabilization in field conditions was performed with 5% lime for both clays and was applied as a 30 cm thick single layer. In the soaked California bearing-ratio (CBR) tests conducted in the laboratory, increases that reach up from 16 and 21 times compared to initial soaked CBR values were observed in green and brown clays, respectively, at the end of 28 days. The high increases observed in soaked CBR values would reduce the upper layer thickness of the roads. The similar improvements are also achieved in unconfined compression and plate loading tests. The comparisons performed with the plate loading tests clearly demonstrated the behavior of the surface to lime and its cure impact. 相似文献
106.
The aim of this study was to investigate long-term seasonal trends and decadal change patterns of monthly mean water vapor
pressure (WVP) observation series at 16 meteorological stations scattered point-wisely over the Southeastern Anatolian Project (GAP) area in Turkey, where large-scale soil and water development projects have been put into practice since the 1970s. The record
length of WVP observation series of each station varied between 31- and 41-years between 1962 and 2002. The monthly mean WVP
observation series of each station was rearranged on seasonal basis. Sequential Mann–Kendall trend test, Sen’s slope estimator,
and Spearman’s rank–order correlation tests were employed for detection of likely trends, and Kruskall–Wallis test was used
to detect decadal variations in WVP series of each observation station. A possible area of representation for each meteorological
station was determined by using the Thiessen polygons technique in a geographical information systems media. It was found
that 15 seasonal WVP series have a positive trend covering 97% of the GAP area in the summer season; although one WVP series
has a negative trend direction. However, in the spring season, 33% of the area had a positive trend, and a negative trend
did not appear in any stations. WVP records in the winter season showed an increasing trend over 19% of the GAP area, whereas
a decreasing trend prevailed in 9% of the area. The study results led us to conclude that the substantial increase of WVP
observations in summer season could be attributed to both the shift from rain-fed agriculture to irrigated agriculture being
made increasingly spacious year by year and building large water reservoirs in the GAP located in a semi-arid region. The
results also indirectly suggested that the historical trends in the WVP parameters might be related to global climate change
phenomenon. 相似文献
107.
In this study, the removal of free cyanide from aqueous solutions by activated carbon was investigated. Effects of metal impregnation (Cu and Ag), aeration, and concentrations of adsorbent and cyanide on the rate and extent of the removal of cyanide were studied. The results have shown that the capacity of activated carbon for the removal of cyanide can be significantly improved (up to 6.3-fold) via impregnation of activated carbon with metals such as copper and silver. Silver-impregnated activated carbon was found to be the most effective at the reduction of cyanide level in solution. This appeared to be coupled with its comparatively high metal content after impregnation process where silver (5.07%) could be more readily loaded on activated carbon than copper (0.43%). Kinetics and equilibrium data for cyanide removal by plain and metal-impregnated activated carbons were determined to be consistent with the pseudo second-order kinetics and the Langmuir adsorption isotherms, respectively. Aeration (0.27 l/min) was found to exert a profound effect on the process leading to a 5.5–49.1% enhancement in the performances of plain and metal-impregnated activated carbons. This enhancement could be attributed to the increase in the availability of active sites on activated carbon for adsorption and the catalytic oxidising activity of activated carbon in the presence of oxygen. Practical limiting capacity of plain, copper- and silver-impregnated activated carbons for the removal of cyanide were experimentally determined to be 19.7, 22.4 and 29.6 mg/g, respectively. 相似文献
108.
Denizhan Vardar Kurultay Öztürk Cenk Yaltırak Bedri Alpar Hüseyin Tur 《Marine Geophysical Researches》2014,35(1):69-85
Although there are many research studies on the northern and southern branches of the North Anatolian fault, cutting through the deep basins of the Sea of Marmara in the north and creating a series of pull-apart basins on the southern mainland, little data is available about the geometrical and kinematical characteristics of the middle strand of the North Anatolian fault. The first detailed geometry of the middle strand of the North Anatolian fault along the southern Marmara shelf, including the Gemlik and Band?rma Bay, will be given in this study, by a combined interpretation of different seismic data sets. The characteristic features of its segments and their importance on the paleogeographic evolution of the southern shelf sub-basins were defined. The longest one of these faults, the Armutlu-Band?rma segment, is a 75-km long dextral strike-slip fault which connects the W–E trending Gençali segment in the east and NE–SW trending Kap?da?-Edincik segment in the west. In this context, the Gemlik Bay opened as a pull-apart basin under the control of the middle strand whilst a new fault segment developed during the late Pleistocene, cutting through the eastern rim of the bay. In this region, a delta front forming the paleoshoreline of the Gemlik paleolake was cut and shifted approximately 60 ± 5 m by the new segment. The same offset on this fault was also measured on a natural scarp of acoustic basement to the west and integrated with this paleoshoreline forming the slightly descending topset–foreset reflections of the delta front. Therefore the new segment is believed to be active at least for the last 30,000 years. The annual lateral slip rate representing this period of time will be 2 mm, which is quite consistent with modern GPS measurements. Towards the west, the Band?rma Bay is a rectangular transpressional basin whilst the Erdek Bay is a passive basin under the control of NW–SE trending faults. When the water level of the paleo-Marmara lake dropped down to ?90 m, the water levels of the suspended paleolakes of Band?rma and Gemlik on the southern shelf were ?50.3 (?3.3 Global Isostatic Adjustment—GIA) and ?60.5 (?3.3 GIA) m below the present mean sea level, respectively. As of today a similar example can be seen between the Sea of Marmara and the shallow freshwater lakes of Manyas and Uluabat. Similarly, the paleolakes of Gemlik and Bandirma were affected by the water level fluctuations at different time periods, even though both lakes were isolated from the Sea of Marmara during the glacial periods. 相似文献
109.
Hakan Karslı 《Geophysical Prospecting》2011,59(1):56-65
Interpreting a post‐stack seismic section is difficult due to the band‐limited nature of the seismic data even post deconvolution. Deconvolution is a process that is universally applied to extend the bandwidth of seismic data. However, deconvolution falls short of this task as low and high frequencies of the deconvolved data are either still missing or contaminated by noise. In this paper we use the autoregressive extrapolation technique to recover these missing frequencies, using the high signal‐to‐noise ratio (S/N) portions of the spectrum of deconvolved data. I introduce here an algorithm to extend the bandwidth of deconvolved data. This is achieved via an autoregressive extrapolation technique, which has been widely used to replace missing or corrupted samples of data in signal processing. This method is performed in the spectral domain. The spectral band to be extrapolated using autoregressive prediction filters is first selected from the part of the spectrum that has a high signal‐to‐noise ratio (S/N) and is then extended. As there can be more than one zone of good S/N in the spectrum, the results of prediction filter design and extrapolation from three different bands are averaged. When the spectrum of deconvolved data is extended in this way, the results show higher vertical resolution to a degree that the final seismic data closely resemble what is considered to be a reflectivity sequence of the layered medium. This helps to obtain acoustic impedance with inversion by stable integration. The results show that autoregressive spectral extrapolation highly increases vertical resolution and improves horizon tracking to determine continuities and faults. This increase in coherence ultimately yields a more interpretable seismic section. 相似文献
110.
The subsurface shear-wave velocity (Vs) is considered to be a key parameter for site characterization and assessment of earthquake
hazard because of its great influence on local ground-motion amplification. Array microtremor measurements are widely used
for the estimation of shear-wave velocities. Compared to other methods such as frequency-wavenumber (f-k) methods, the spatial
autocorrelation (SPAC) method requires fewer sensors and thus is relatively easier to implement and gives robust estimations
of shear-wave velocity profiles for depths down to a few hundred meters. The quantity derived from observed data is the SPAC
coefficient, which is a function of correlation distance, frequency and phase velocity. Generally, estimation of Vs profiles
is a two stage process: Estimation of the dispersion data from the SPAC coefficients and inversion of the dispersion data
for shear-wave velocity structure. In this study, instead of inverting dispersion curves, a more practical approach is used;
that is, observed SPAC coefficients are directly inverted for the S-wave velocities. A synthetic case and a field data application
are presented to test the potential of the inversion algorithm. We obtain an iterative damped least-squares solution with
differential smoothing. The differential smoothing approach constrains the change in shear-wave velocities of the adjacent
layers and thus stabilizes the inversion. 相似文献