Effect of Different Leachate/Acetate Ratios in a Submerged Anaerobic Membrane Bioreactor (SAnMBR)

Leachate treatment using a membrane bioreactor is an effective method. This study presents a configuration including an anaerobic bioreactor and a membrane module, called submerged anaerobic membrane bioreactor (SAnMBR), for treating influent with leachate/acetate rations (L/A), that were kept to be 10, 25, 50, 75, and 100% at a constant SRT (100 days). COD removal decreased from 85 to 75% when the L/A ratio increased from 10 to 100. To prevent membrane fouling, a SAnMBR was operated in the case of circulation of mixed liquor under continuous and intermittent suction. The average fluxes were 2.60 and 0.40 L/m² h at the periods of intermittent and continuous suction, respectively. The methane production varied between 0.25 and 0.32 L CH₄/g COD_removed.     

Experimental measurements of seismic velocities on core samples and their dependence on mineralogy and stress; Witwatersrand Basin (South Africa)

Physical property measurements were integrated with mineralogical analyses to better understand the nature of the seismic reflectivity of the deepest (>3.5 km depth) gold ore body (Carbon Leader Reef). The CLR lies at depths between 3.5 km and 4.5 km below the surface. Over 50 drill-core samples were selected for geochemical analyses, density and seismic velocity measurements. Ultrasonic measurements were conducted at ambient and elevated stresses, using transducers operating at 0.5 MHz. The study reveals that P-wave velocities generally increase with increasing bulk density. The CLR conglomerate, the gold-bearing reef, has slightly higher P-wave velocity (～5070–5468 m/s) and density values (～2.78 g/cm³) amongst the quartzitic units, possibly due to its massive pyrite content. The quartzite hangingwall and footwall rocks to the CLR exhibit similar P-wave velocity (～5028–5480 and ～4777–5211 m/s, respectively) and density values (～2.68 and 2.66 g/cm³, respectively). The reflection coefficients calculated at the interface between the CLR conglomerate and its hangingwall and footwall units range between ～0.02 and 0.05 which is below the required minimum reflection coefficient value of 0.06 to produce a strong reflection between two lithological boundaries. This suggests that seismic reflection methods might not be able to directly image the CLR, as observed from its poor reflectivity in the 3D seismic data. Samples were also subjected to stresses of up to 65 MPa to simulate in situ-like conditions and to investigate the dependence of seismic velocities on applied stresses. P-wave velocities increase with progressive loading, but at different rates in shale and quartzite rocks as a result of the presence of micro-defects.     

Analytical fragility assessment using unscaled ground motion records

It is desirable that nonlinear dynamic analyses for structural fragility assessment are performed using unscaled ground motions. The widespread use of a simple dynamic analysis procedure known as Cloud Analysis, which uses unscaled records and linear regression, has been impeded by its alleged inaccuracies. This paper investigates fragility assessment based on Cloud Analysis by adopting, as the performance variable, a scalar demand to capacity ratio that is equal to unity at the onset of limit state. It is shown that the Cloud Analysis, performed based on a careful choice of records, leads to reasonable and efficient fragility estimates. There are 2 main rules to keep in mind for record selection: to make sure that a good portion of the records leads to a demand to capacity ratio greater than unity and that the dispersion in records' seismic intensity is considerable. An inevitable consequence of implementing these rules is that one often needs to deal with the so‐called collapse cases. To formally consider the collapse cases, a 5‐parameter fragility model is proposed that mixes the simple regression in the logarithmic scale with logistic regression. The joint distribution of fragility parameters can be obtained by adopting a Markov Chain Monte Carlo simulation scheme leading directly to the fragility and its confidence intervals. The resulting fragility curves compare reasonably with those obtained from the Incremental Dynamic Analysis and Multiple Stripe Analysis with (variable) conditional spectrum–compatible suites of records at different intensity levels for 3 older reinforced concrete frames with shear‐, shear‐flexure‐, and flexure‐dominant behavior.     

Factors controlling the morphological evolution of the Çanakkale Strait (Dardanelles, Turkey)

Seismic profiling, bathymetric and physical oceanographic data collected from the Çanakkale Strait revealed that the morphological evolution of the strait has been controlled by tectonic activity, and sediment erosion and deposition. Sediments in the strait have been sourced mostly by rivers draining the Biga Peninsula during lowstand periods. In highstand periods, by contrast, deposits in the strait were reworked by currents. The seafloor morphology of the Çanakkale Strait is also controlled by a sequence of factors ranging from tectonics to current erosion and deposition. Channel deposits overlying the basement are being eroded at the narrower, meandering central section of the strait (the Nara Passage) due to high current velocities. The eroded sediments are deposited in the relatively linear and wider, northern and southern sectors of the strait exposed to low current velocities. As a result, the high-energy areas are more deeply incised due to the erosion, whereas deposition elevates the seafloor in the areas exposed to lower current energy. Three strike-slip faults, which possibly relate to the activity of the North Anatolian Fault Zone, are responsible for the irregular shape of the strait and this, in turn, controls the current velocity along the strait. The high-energy conditions probably commenced with the latest invasion of Mediterranean waters some 12 ka b.p., and have continued as a two-layered current system to the present day.     

Seismic performance of masonry buildings during the 2007 Bala,Turkey earthquakes

A field investigation was conducted near the town of Bala after two strong earthquakes struck the region on December 20 and 27, 2007. The main objectives of this study are to present the results of the field investigation and examine the characteristics of the recorded ground motions and the corresponding response spectra. The focus of the research was on the causes of damage and failures commonly observed in masonry structures. This study classifies single family masonry dwellings in rural areas and investigates the seismic damage in unreinforced masonry structures. Turkish Earthquake Code requirements for masonry buildings are summarized and compared with the field observations. Our field investigation showed that there has been lack of quality control and regulation for the masonry construction. Diagonal shear cracking and out-of-plane failure were the two major factors that contributed to widespread damage in masonry structures.     

Comparing classical statistic and machine learning models in landslide susceptibility mapping in Ardanuc (Artvin), Turkey

Natural Hazards - Landslide susceptibility maps provide crucial information that helps local authorities, public institutions, and land-use planners make the correct decisions when they are...     

An Experimental and Theoretical Approach on the Modeling of Sliding Response of Rock Wedges under Dynamic Loading

The stability of rock slopes under dynamic loading in mining and civil engineering depends upon the slope geometry, mechanical properties of rock mass and discontinuities, and the characteristics of dynamic loads with time. The wedge failure is one of the common forms of slope failures. The authors presented some stability conditions for rock wedges under dynamic loading and they confirmed their validity through the laboratory experimental studies in a previous paper in 2000, which is often quoted by others to validate their softwares, including some commercial software. In this study, the authors investigate the sliding responses of rock wedges under dynamic loads rather than the initiation of wedge sliding. First, some laboratory model tests are described. On the basis of these model tests on rock wedges, the theoretical model proposed previously is extended to compute the sliding responses of rock wedges in time domain. The proposed theoretical model is applied to simulate the sliding responses of rock wedge model tests and its validity is discussed. In the final part, the method proposed is applied to actual wedge failures observed in 1995 Dinar earthquake and 2005 Pakistan–Kashmir earthquake, and the results are discussed.     

Simultaneous parameter identification of a heterogeneous aquifer system using artificial neural networks

An artificial neural network (ANN) model is proposed for the simultaneous determination of transmissivity and storativity distributions of a heterogeneous aquifer system. ANNs may be useful tools for parameter identification problems due to their ability to solve complex nonlinear problems. As an extension of previous study—Karahan H, Ayvaz MT (2006) Forecasting aquifer parameters using artificial neural networks, J Porous Media 9(5):429–444—the performance of the proposed ANN model is tested on a two-dimensional hypothetical aquifer system for transient flow conditions. In the proposed ANN model, Cartesian coordinates of observation wells, associated piezometric heads and observation time are used as inputs while corresponding transmissivity and storativity values are used as outputs. The training, validation and testing processes of the ANN model are performed under two scenarios. In scenario 1, all the sampled data are used through the simulation time. However, in the scenario 2, there are data gaps due to irregular observations. By using the determined synaptic network weights, transmissivity and storativity distributions are predicted. In addition, the performance of the proposed ANN is tested for different noise data conditions. Results showed that the developed ANN model may be used in simultaneous aquifer parameter estimation problems.