Evaluating Thickness of Bauxite Deposit Using Indicator Geostatistics and Fuzzy Estimation

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.     

Crustal Seismicity In and Around Turkey

Vertical and horizontal variations of the frequency of crustal earthquakes (h ≤ 35 km) that have occurred in and around Turkey are analyzed, using data from the Global Hypocenter Data Base and the IRIS data for the period 1964–1998. Fits of various magnitude scales to the observations have been used to construct a homogeneous catalogue. Depth distribution of the parameters derived from the Gutenberg–Richter relationship reveals that there is a depth dependence in the a- and b-values of the frequency distribution. It is observed that unknown focal depths (0, 10, 33 km) are dominant in the total seismicity reported, and give rise to substantial changes to the vertical distribution of these parameters. It is also observed that the parameters of either a or b alone may not be used as a measure of regional seismicity of the study area in which high and low seismic activity observed over short distances. In contrast, distribution of modal (a/b) values provides detailed images of the local areas presented by high and low seismic zones. This study presents evidence that low b-values are associated with major strike-slip faults, particularly exhibiting high apparent stresses. This revised version was published online in June 2006 with corrections to the Cover Date.     

A short cut numerical method for determination of periods of free oscillations for basins with irregular geometry and bathymetry

A short cut numerical method for evaluation of the modes of free oscillations of the basins which have irregular geometry and bathymetry is presented in this paper. In the method, a single wave is inputted to the basin as an initial impulse. The respective agitation in the basin is computed by using the numerical method solving the nonlinear form of long wave equations. The time histories of water surface fluctuations at different locations due to propagation of the waves in relation to the initial impulse are stored and analyzed by the fast Fourier transform technique (FFT) and energy spectrum curves for each location are obtained. The frequencies of each mode of free oscillations are determined from the peaks of the spectrum curves. The method is tested by using regular shaped flat bottom basins with different depths. The computed periods of free oscillations are compared with the theoretical values. The accuracy and performance of the method are discussed. As a case study for the application to the basins of irregular shape and bathymetry, the periods of free oscillations of the sea of Marmara is determined and discussed.     

Modeling Aeration Efficiency of Stepped Cascades by Using ANFIS

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.     

Performance improvement studies of masonry houses using elastic post‐tensioning straps

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.     

A Review of Research and Development of Wind Energy in Turkey

During the end of the 20^th and the beginning of the 21^st centuries, interest has risen in new and renewable energy sources, and especially wind energy for electricity generation. In a short time, wind energy has been welcomed by society, industry and politicians as a clean, practical, economical and environmentally friendly alternative to existing fossil fuels. As a result of extensive studies on this topic, wind energy has recently been applied in various industries, and has started to compete with other energy resources. Wind energy applications and turbine installations at different scales have increased since the beginning of this millennium. Technically installed wind turbines capacity factors have high values in most areas of Turkey. It is seen that, in general, the modeling of wind speed and its parameters have been studied and researched rather than wind power technological development in Turkey. Wind investors had doubts about uncertainties in the renewable energy policies. After May 2007, an energy efficiency law was accepted and 10 years of electricity generation by renewable sources is considered as guaranteed by the Turkish government. The installed wind power has reached 131.35 MW in Turkey and it is expected that this value will be increased to 808.81 MW by the end of 2008. The dependence of strong technological and economical development on Turkey's energy needs have increased and new national or international sources have to be taken into account for the energy sector of the country. It is clear that this source gap could be filled by using the high potential of wind power, which is estimated at 58 GW. It is expected that installed wind power to supply up to 5% of electricity consumption by 2015 and for the end of 2008 this ratio will increase to 2% (it is currently ca. 1.0%). However, unexpected and unpredicted wind power applications have occurred on November 1^st, 2007 in Turkey. It has been announced that 78,000.00 MW wind power investments have been applied by the Energy Market Regulatory Authority (EMRA). This is a new era for the Turkish energy sector and there is no model for this new situation. Therefore, in this paper, wind energy in Turkey is reviewed and opened up for further discussion.     

Ground-motion characterization for the probabilistic seismic hazard assessment in Turkey

This study describes the methodology implemented to establish the ground-motion logic-tree for national probabilistic seismic hazard map of Turkey for shallow active crustal regions. The presented procedure provides quantitative information to guide the hazard experts while establishing the logic tree to capture the epistemic uncertainty in ground-motion characterization. It uses non-data-driven and data-driven testing methods to identify and rank candidate ground-motion prediction equations (GMPEs) under a specific ground-motion database. The candidate GMPEs are subjected to visual inspection and are classified into center, body and range (CBR) spectral estimates for a proper consideration of epistemic uncertainty. The GMPEs classified into CBR are then used in a suite of seismic hazard sensitivity analysis to establish the most suitable GMPE logic-tree whose spectral estimates are not biased by any one of the GMPEs in the logic-tree structure. The sensitivity analysis considers normalized spectral ordinates and is not manipulated by the spectral amplitudes. The proposed procedure is inherited from the relevant studies of the Earthquake Model of the Middle East (EMME; www.efehr.org:8080/jetspeed/portal/emme.psml) regional seismic hazard project. This paper also highlights the similarities and differences in ground-motion characterization between EMME and our approach.     

A statistical assessment on global drift ratio demands of mid-rise RC buildings using code-compatible real ground motion records

Over the past 20 years, significant socio-economic losses have been encountered in Turkey due to several moderate to large earthquakes. The studies published after the earthquakes concurringly emphasized that multistory reinforced concrete (RC) buildings, mostly 3–7 story ones, collapsed or were heavily damaged as a result of inadequate seismic performance. Global drift ratio demands are mostly used as a representative quantity for determining the behavior of structures when subjected to earthquakes. In this study, three representative mid-rise RC buildings are analyzed by nonlinear time history analysis using code-compatible real ground motion record sets and the calculated global drift ratio demands of these buildings are statistically evaluated. Ground motion record sets compatible with the design spectrum defined for local soil classes in the Turkish Earthquake Code (TEC-2007) are used for the analyses. In order to evaluate the effect of the number of ground motions on drift ratio demands, five different ground motion record sets with 7, 11 and 15 ground motion records are used separately for each local soil class. Results of this study indicate that (1) the dispersion of global drift ratio demands calculated for individual ground motion records in record sets is high, (2) local soil class has no significant effect on dispersion. However, dispersion increases in a direct proportion to the number of ground motion records in a record set, (3) the mean of global drift ratio demands calculated for different ground motion record sets may differ although they are compatible with the same design spectrum, (4) the mean of the drift demands obtained from different ground motion record sets compatible with a particular design spectrum can be accepted as simply random samples of the same population at 95% confidence level.     

The QuakeSim Project: Web Services for Managing Geophysical Data and Applications

We describe our distributed systems research efforts to build the “cyberinfrastructure” components that constitute a geophysical Grid, or more accurately, a Grid of Grids. Service-oriented computing principles are used to build a distributed infrastructure of Web accessible components for accessing data and scientific applications. Our data services fall into two major categories: Archival, database-backed services based around Geographical Information System (GIS) standards from the Open Geospatial Consortium, and streaming services that can be used to filter and route real-time data sources such as Global Positioning System data streams. Execution support services include application execution management services and services for transferring remote files. These data and execution service families are bound together through metadata information and workflow services for service orchestration. Users may access the system through the QuakeSim scientific Web portal, which is built using a portlet component approach.     

Forward modelling receiver functions for crustal structure beneath station TBZ (Trabzon, Turkey)

We use teleseismic three-component digital data from the Trabzon, Turkey broadband seismic station TBZ to model the crustal structure by the receiver function method. The station is located at a structural transition from continental northeastern Anatolia to the oceanic Black Sea basin. Rocks in the region are of volcanic origin covered by young sediments. By forward modelling the radial receiver functions, we construct 1-D crustal shear velocity models that include a lower crustal low-velocity zone, indicating a partial melt mechanism which may be the source of surfacing magmatic rocks and regional volcanism. Within the top 5 km, velocities increase sharply from about 1.5 to 3.5 km s⁻¹. Such near-surface low velocities are caused by sedimentation, extending from the Black Sea basin. Velocities at around 20 km depth have mantle-like values (about 4.25 km s⁻¹ ), which easily correlate to magmatic rocks cropping out on the surface. At 25 km depth there is a thin low-velocity layer of about 4.0 km s⁻¹. The average Moho velocity is about 4.6 km s⁻¹, and its depth changes from 32 to 40 km. Arrivals on the tangential components indicate that the Moho discontinuity dips approximately southwards, in agreement with the crustal thickening to the south. We searched for the solution of receiver functions around the regional surface wave group velocity inversion results, which helped alleviate the multiple solution problem frequently encountered in receiver function modelling.
Station TBZ is a recently deployed broadband seismic station, and the aim of this study is to report on the analysis of new receiver function data. The analysis of new data in such a structurally complex region provides constraining starting models for future structural studies in the region.