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101.
H. U?ur Koyliioglu Ahmet ?. Çakmak Søren R.K. Nielsen 《Soil Dynamics and Earthquake Engineering》1997,16(2):95-112
A nonlinear hysteretic model for the response and local damage analyses of reinforced concrete shear frames subject to earthquake excitation is proposed, and, the model is applied to analyse midbroken reinforced concrete (RC) structures due to earthquake loads. Each storey of the shear frame is represented by a Clough and Johnston hysteretic oscillator with degrading elastic fraction of the restoring force. The local damage is numerically quantified in the domain [0,1] using the maximum softening damage indicators which are defined in closed form based on the variation of the eigenfrequency of the local oscillators due to the local stiffness and strength deterioration. The proposed method of response and damage analyses is illustrated using a sample 5 storey shear frame with a weak third storey in stiffness and/or strength subject to sinusoidal and simulated earthquake excitations for which the horizontal component of the ground motion is modeled as a stationary Gaussian stochastic process with Kanai-Tajimi spectrum, multiplied by an envelope function. 相似文献
102.
Evaluating the geological properties of a mineral deposit is a fundamental task for mine planning and it requires an assessment of reserve parameters such as thickness and grade. This paper presents a linguistic model for estimating bauxite thickness within a deposit in a fuzzy environment using indicator geostatistics and fuzzy modeling. The proposed model consists of two main stages: determining the orebody boundary and estimating the thickness. In order to estimate the thickness, a rule‐based fuzzy inference mechanism has been developed based on data statistics. Results and performance of the model have been compared with that of a well‐known conventional technique, geostatistics (kriging), and it is shown that the proposed model has bigger estimation power. In addition, the fuzzy approach is more flexible than the kriging approach. The fuzzy methodology used in the present paper is convenient for modeling reserve parameters. 相似文献
103.
A technique for improving MODIS standard snow products for snow cover monitoring over Eastern Turkey
Daily snow cover maps at 500 m resolution are available from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors
on NASA's Terra and Aqua satellites. However, information of the ground can only be obtained during clear sky conditions.
In addition, the spectral similarity between clouds and snow in the visible part of the spectrum causes some ambiguities in
separation of them. The dynamic behavior of clouds with their tendency to move faster often enables discrimination between
cloud and snow, since snow remains relatively stationary. In this study, a daily merging methodology to combine Terra and
Aqua based snow maps are proposed, and the benefits of this combination are evaluated. The methodology was tested for Eastern
Turkey covering the period from December 2002 to March 2003. Merged maps derived from the standard daily snow maps from Terra
(MOD10A1) and Aqua (MYD10A1) reduce the cloud cover present in any one image alone, provide better representation of the surface
snow cover, and indicate better agreement with ground snow measurements than when either one is used alone. For “on the ground
data date” analyses yielded 31% match ratios for MOD10A1 and MYD10A1, whereas combined images enabled 38%. One- to 2-day temporal
window shifting enabled further 7% and 5% improvements in match ratios, respectively. The maximum improvement of 25% was achieved
in January of 2003. The proposed methodology provides an easy and effective way to improve snow cover maps with little effort
and provides fewer cloud-contaminated images for snow monitoring, for hydrology, and water resource management. 相似文献
104.
Nizamettin Demirkıran Ahmet EkmekyaparAsım Künkül Ahmet Baysar 《International Journal of Mineral Processing》2007
Cementation of copper from zinc containing copper solutions using metallic zinc was studied in this work. The effect of copper, zinc and ammonium chloride concentration, stirring speed, pH and temperature on the cementation of copper was determined. Cementation rate increased with initial copper concentration, stirring speed and temperature. pH variation from 1 to 4 increased the cementation rate but at higher pH, the rate was not significantly effected. The cementation rate of copper increased with Zn2+ ion concentration. However, the rate of this rise was slightly less compared to the rise that occurred in the Zn2+ ions free copper solution. 相似文献
105.
Atila Yildiz Ahmet Aksoy Gul Nilhan Tug Cemil Islek Dilek Demirezen 《Journal of Atmospheric Chemistry》2008,60(1):71-81
The objective of this study was to determine the air pollution level of Ankara and to generate the air pollution map of this
city by using Pseudevernia furfuracea (L.) Zopf as a biomonitor. Lichen samples were collected from unpolluted area at Yaprakli Mountains, Cankiri in November
2002 and transplanted to 27 localities in Ankara. Lichen samples were retrieved following an exposure of 3 and 6 months. Heavy
metal, Cu, Mn, Ni, Pb and Zn, contents were determined by using inductively coupled plasma spectrometry (ICP). The chlorophyll
a and b contents were determined by using DMSO method. The increase in Ni, Pb, Zn and chlorophyll a content of the specimens
were statistically important. All the increases and decreases in the variables could be explained by the environmental stress
like pollution, but it is hard to say that this is the only reason of these changes, also climatic conditions, seasons, strength
of the light and the physiological status of the plant itself effective on these changes. According to the results of heavy
metal analysis Pseudevernia furfuracea continued to accumulate heavy metals and worked well as a biomonitor. The air pollution level of Ankara shows great variations
because of the great area of the city. 相似文献
106.
Onur Tan Eleftheria E. Papadimitriou Zumer Pabucçu Vassilis Karakostas Ahmet Yörük Kostas Leptokaropoulos 《Acta Geophysica》2014,62(6):1283-1309
A detailed investigation of microseismicity and fault plane solutions are used to determine the current tectonic activity of the prominent zone of seismicity near Samos Island and Kusadasi Bay. The activation of fault populations in this complex strike-slip and normal faulting system was investigated by using several thousand accurate earthquake locations obtained by applying a double-difference location method and waveform cross-correlation, appropriate for areas with relatively small seismogenic structures. The fault plane solutions, determined by both moment tensor waveform inversions and P-wave first motion polarities, reveal a clear NS trending extension direction, for strike slip, oblique normal and normal faults. The geometry of each segment is quite simple and indicates planar dislocations gently dipping with an average dip of 40–45°, maintaining a constant dip through the entire seismogenic layer, down to 15 km depth. 相似文献
107.
108.
Elena Hubareva Leonid Svetlichny Ahmet Kideys Melek Isinibilir 《Estuarine, Coastal and Shelf Science》2008
In October 2005 spatial distribution of live and dead Acartia clausi and Acartia tonsa was studied in the Black and Marmara Seas and near the Marmara Sea inlet of the Bosphorus, in order to understand their fate upon transportation between two seas. The morphometric characteristics in both species from all studied areas, and the decreased abundance of A. clausi and A. tonsa from the Black Sea towards the Marmara Sea indicate that the Marmara Sea Acartia populations are formed by recruitment from the Black Sea. We observed mass mortality of A. clausi in the Marmara Sea near the Prince Islands. The majority of carcasses (66% of total A. clausi numbers in the Marmara Sea) were found in the salinity gradient layer. 相似文献
109.
The physical process of oxygen transfer or oxygen absorption from the atmosphere acts to replenish the used oxygen, a process termed re‐aeration or aeration. Aeration enhancement by macro‐roughness is well‐known in water treatment and one form is the aeration cascade. The macro‐roughness of the steps significantly reduces the flow velocities and leads to flow aeration along the stepped cascade. In this paper, the aeration efficiency in stepped cascade aerators was modeled by using the Adaptive Network Based Fuzzy Inference System (ANFIS). The obtained model was tested with experimental data. Test results showed that ANFIS can be used to estimate the aeration efficiency in stepped cascade aerators. 相似文献
110.
Unreinforced masonry houses are composed of building blocks with weak inter‐binding action between them which commonly possess low tensile strength. The principal tensile stresses generated by out‐of‐plane bending and in‐plane shear forces cannot be tolerated well and leads to heavy structural damage and brittle collapse beyond linear capacity of the material. Remedies such as externally applied mesh reinforcement and post‐tensioning improves post and pre‐cracking performances; however, yielding of reinforcement material or shortening of walls due to cracking causes loss of integrity and post‐tensioning force. This paper discusses a research programme on earthquake strengthening of masonry houses using post‐tensioning by elastomeric straps and related shaking table tests on 1/10 scale single storey rural dwelling models. The aim of the study is to assess the use and effectiveness of post‐tensioning rubber straps at several different configurations especially for houses with heavy earth roofs supported on wooden logs. Full‐scale application can be conducted using scrap automobile tyres, which might be implemented as an economic and environment friendly alternative strengthening technique for poor residents of low‐cost dwellings. The performance and validity of the proposed strengthening techniques were tested on 1/10 scale models using a simplistic shaking table. The structural performance of the reinforced models with vertical post‐tensioning rubber straps was significantly improved as compared to the original specimen; the results were even better when vertical and horizontal straps were used. Obtained results show promise for seismic strengthening using rubber straps for post‐tensioning. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献